JP2001154152A - Optical engine, and video displaying device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display technique capable of achieving brightness and high picture quality under conditions of a small size, lightweight and low cost. SOLUTION: Two polarization converting elements for converting the polarized direction of lights and two color separating and synthesizing means for reflecting or transmitting lights only in a specific wavelength area are combined, or three polarization converting elements and a color separating and synthesizing means are combined on the optical axis of a reflective liquid crystal display element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display device for projecting an image on a screen using a light valve element such as a liquid crystal panel or a reflection type liquid crystal display device, for example, a liquid crystal projector device and a reflection type image display projector device. , A liquid crystal television, and a video display device such as a projection display device.

[0002]

2. Description of the Related Art There is known a projection type image display apparatus such as a liquid crystal projector which irradiates a light valve element such as a liquid crystal panel with light from a light source such as a light bulb to enlarge and project an image on the light valve element.

[0003] This type of video display device is a device in which light from a light source is changed into light and shade for each pixel by a light valve element, adjusted, and projected onto a screen or the like. For example, a twisted nematic (TN) type liquid crystal display element, which is a typical example of a liquid crystal display element, has a polarization direction before and after a liquid crystal cell formed by injecting liquid crystal between a pair of transparent substrates having a transparent electrode coating. Are arranged 90 degrees apart from each other by combining the action of rotating the plane of polarization by the electro-optic effect of the liquid crystal and the action of selecting the polarization component of the polarizing plate, thereby reducing the incident light. Image information is displayed by controlling the amount of transmitted light. In recent years, in such a transmission type or reflection type image display device, the size of the device itself has been reduced, and the performance such as resolution has been rapidly improved.

[0004] For this reason, a display device using a light valve element such as an image display element has been miniaturized and improved in its performance. A projection type video display device as a device has also been newly proposed. In particular, this type of projection type video display device is required to be small in size and to obtain a bright image to every corner of the screen.
However, the conventional projection-type image display device has a problem that it is large in size, and the performance such as brightness and image quality of a finally obtained image is insufficient.

For example, to reduce the size of the entire liquid crystal display device,
It is effective to reduce the size of the light valve element, that is, the liquid crystal display element itself. However, when the size of the liquid crystal display element is reduced, the area illuminated by the liquid crystal means becomes smaller. Is smaller, the ratio of the amount of luminous flux on the liquid crystal display element to the total amount of luminous flux emitted by the light source (hereinafter referred to as light utilization efficiency)
And the peripheral portion of the screen is dark. Further, since the liquid crystal display device can use only one-way polarized light, about half of light from a light source that emits randomly polarized light is not used. As an optical system for irradiating a liquid crystal display element with random polarized light from a light source aligned in one direction of polarization, a polarization conversion element such as a polarization beam splitter as disclosed in JP-A-4-63318 is known. Utilizing random polarized light emitted from the light source as P
There is a type that separates polarized light and S-polarized light and combines them using a prism.

Further, by using this, in a conventional optical system, particularly in an illumination optical system using a reflection type liquid crystal display device, the polarization beam splitter and the reflection type liquid crystal display element are combined to turn on and off an image. The light is analyzed by changing the polarization direction according to the gradation expression, and then the image is projected on the screen by the projection lens.
In this case, there is a problem of color unevenness and contrast reduction due to the polarization beam splitter. That is, since the characteristics of the transmittance of the P-polarized light and the reflectance of the S-polarized light with respect to the incident angle of the light change, the transmittance and the reflectance unevenness of the polarizing beam splitter occur for the light of a predetermined angle of the illumination optical system. . As a result, the image quality projected on the screen deteriorates.

A transparent material sandwiching a PB film as disclosed in JP-A-09-054213 is made of a glass material having an absolute value of a photoelastic coefficient of 1.5 × 10 ⁻⁸ cm ² / N or less. There is a method in which the use of a polarized light beam splitter reduces the birefringence in the polarizing beam splitter glass material and improves the contrast on the screen. However, in the present invention, the weight of the polarizing beam splitter glass material itself is heavy (about twice or more as compared with the related art), and the cost is also high. However, other than the embodiment of the present invention, a general optical system uses three polarizing beam splitters for each of three RGB reflective panels, so that the size, weight, and cost of the optical system must be reduced. Is not considered.

In an optical system using a reflection type liquid crystal display device or the like, a dichroic prism or a dichroic mirror having a dichroic coating applied to a color separation / combination system is used, and polarization when entering and exiting the color separation / combination system is used. The direction of light changes depending on the direction. It is known that the characteristics of a dichroic coat change depending on the polarization direction of incident light. That is, a difference occurs in the wavelength band to be separated between the P-polarized light and the S-polarized light. More specifically, on the dichroic blue reflecting surface, the half-value wavelength of the P-polarized light becomes lower than that of the S-polarized light. in this case,
The light incident as S-polarized light is separated into reflected light and transmitted light according to the half-wavelength λs of S-polarized light on the blue reflection coating surface. When the image information is white, the light is polarization-converted to P-polarized light by the blue reflective liquid crystal display element and re-enters the blue reflective coating surface. This time, the light is separated into reflected light and transmitted light according to the P-polarized light half-value wavelength λp. At this time, the half-value wavelength is lower,
There is a wavelength band that is transmitted without being reflected. Since the transmitted light in the wavelength band cannot be used in an image display device, the light having the half-value wavelength difference is lost, and the brightness decreases and the color performance deteriorates. The same happens with the red reflective surface. Therefore, the light corresponding to the shift of the wavelength band cannot be used. As a result, there arises a problem that the light use efficiency and the chromaticity performance of the video display device are reduced.

[0009] Further, the contrast of the image display device is one of the important performances. In order to improve the contrast, in order to improve the contrast, between the illumination system and the polarizing beam splitter and / or between the polarizing beam splitter and the projection lens. On the other hand, it is effective to insert a polarizing plate, but in the conventional configuration,
Since all the red, green and blue lights pass through the polarizing plate, the temperature of the polarizing plate rises, the contrast decreases,
Problems such as burning of the polarizing plate have occurred.

[0010] As described above, it is necessary to take measures from the viewpoints of reducing the size, weight, and cost of the optical system and the projection type video display device itself while maintaining the brightness and image quality of the video display device.

[0011]

In the above prior art,
While ensuring the brightness and image quality performance of the video display device,
There is a need for a method of reducing the size, weight, and cost of the device itself. That is, brightness securing,
Contrast improvement, size reduction of device itself, weight reduction,
In order to reduce the cost, the light efficiency of the dichroic prism, which is a polarizing beam splitter and color separation / synthesis means, has been improved.
It is necessary to devise a scheme for entering and exiting the reflective panel and a scheme for efficient arrangement of each.

An object of the present invention is to provide a video display technique capable of securing brightness and high image quality performance at a small size and at low cost with respect to the above-mentioned problems in the prior art.

[0013]

A reflection type image display element for forming an optical image corresponding to an image signal from light emitted from a light source unit, an illumination optical system for irradiating the reflection type image display element with light, and a reflection optical system. An optical engine for an image display device, comprising: projection means for projecting light emitted from the type image display element; and two polarization conversion elements for changing the polarization direction of light on the optical axis of the reflection type image display element. Combination configuration with two color separation / combination means for reflecting or transmitting light only in a specific wavelength range,
Alternatively, a combination configuration of three polarization conversion elements and one color separation / combination unit is provided. With such a configuration, conventionally,
It is common to combine individual color separation / synthesis means with three or more polarization beam splitters to input / output light to the reflection type image display device of each color of RGB. A total of 5 to 6 polarization beam splitters and color separation are used. It needed a means of synthesis.
Since this can be reduced to a total of four, downsizing, weight reduction, and significant cost reduction are also possible.

The color synthesizing means is arranged on the optical path after the polarization conversion element and on the optical axis immediately before the projection lens. This makes it possible to combine light of each color of RGB only by the color combining means, and reduce the number of components of the optical element. In addition, since the wavelength band of color synthesis can be controlled and a dielectric multilayer film for color synthesis such as an inclined film can be arranged, it is possible to improve color uniformity and purity. In addition, the optical performance is improved, and the size, weight, and cost can be significantly reduced.

[0015] Further, two polarization conversion elements are used at positions immediately before light enters and exits each of the three R, G, and B components of the reflection-type image display element. Outgoing light, which is an image obtained by combining one of the polarization conversion elements or the color separation means, and reflecting each of the three RGB of the reflection-type image display elements, is analyzed by the two polarization conversion elements. One color synthesizing unit is arranged at a portion where the light passes, and the light emitted from the color synthesizing unit is projected onto a screen surface or the like by the projection unit.

In such a configuration, only the color separation means is used for RGB.
Light of each color can be separated, and the number of components of the optical element can be reduced. In addition, since the wavelength band of color separation can be controlled for the color of light incident on each color panel, and a dielectric multilayer film for color separation such as an inclined film can be arranged, color uniformity and color purity can be improved. It is possible to increase. With this configuration, the optical performance is further improved, and further with this configuration, there is an effect that the size and weight are reduced, and the members and devices are reduced in size and weight, and thereby the cost can be significantly reduced.

Further, the two polarization conversion elements and the two color separation / synthesis means, or the three polarization conversion elements and the one color separation / synthesis means are arranged on the optical axis of the reflection type image display element. An optical system configuration including a combination configuration and a specific wave selection wavelength plate that converts the polarization of light in a specific wavelength band into a polarization direction at a predetermined angle. This allows any position in the configuration
Any number of sheets can be inserted, and the polarization direction of light in the wavelength band of each color such as RGB can be freely changed, so that the influence of the change in the characteristics of the dichroic film due to the P-polarized light and S-polarized light passing through the color separation / combination means can be reduced In addition, the efficiency of color separation or color synthesis by the polarization beam splitter is improved, and the configuration of the present invention can be easily realized.

A green light separating means, such as a dichroic mirror or a dichroic prism, for separating only the G light by transmitting or reflecting the light, is disposed between the light source and the optical element for changing the polarization direction of the specific wavelength band. Separate the light in advance. The separated G light is used to obtain an image using a dedicated polarization beam splitter and an image display element. With this configuration, energy can be separated into G light, red light, and blue light, the amount of heat in each optical path is dispersed, and an optical component having low heat resistance such as a polarizing plate can be used.

R light separated by green light separating means,
For blue light, only one of the blue light has its polarization direction changed by an optical element that changes the polarization direction in a specific wavelength range, and then enters the polarization beam splitter. At this time, the characteristics are changed in the specific wavelength region at the boundary of the G light region, that is, the band of approximately 510 to 580 nm. The R light and the blue light having different polarization directions are separated by the polarization beam splitter, and are polarization-converted and reflected by the respective image display elements, and an image is obtained by the polarization beam splitter. Here, the polarization directions may be aligned using an optical element that converts the polarization direction in the specific wavelength range again. With such a configuration, two polarization images can be obtained simultaneously by one polarization beam splitter, color separation is performed by dichroic coating or the like, and compared with a case where a polarization beam splitter is arranged in each optical path.
A small and lightweight optical engine can be designed. Green,
The red and blue light images are synthesized by a color synthesizing means, for example, a dichroic mirror or a dichroic prism, and are projected as one color image on a screen by a projection lens.

With this configuration, the color separation / synthesis means can be separated and the polarization of the light passing therethrough can be limited to S-polarization or P-polarization. Further, in order to separate the G light before entering the polarizing beam splitter disposed immediately before the image display element,
Light energy is dispersed. This makes it possible to insert a polarizing plate or the like between the green light separating means and the polarizing beam splitter disposed immediately before the image display element, thereby improving the contrast of the projected image. Similarly, only green is separated between the polarizing beam splitter and the projection lens, so that light energy is dispersed and a polarizing plate can be inserted.

Further, an optical element for polarization-converting light in a specific wavelength band is inserted between the polarization separating element and the color synthesizing means in the optical path of the red and blue lights, and the light emitted from the optical element is transmitted to the color synthesizing means. The reflection and transmission characteristics of the color synthesizing unit can be improved by making the S-polarized light when reflected and incident on the projection unit and the P-polarized light when transmitted and incident on the projection unit. .

Alternatively, the color separation / synthesis means is a dichroic prism, and a chamfer is provided on one side of the diagonal prism perpendicular to the optical axis in the color separation direction, which is larger than the other side. Are arranged. With this configuration, when these optical elements are incorporated in the housing, the interference between the polarization conversion element and the color separation / synthesis unit in the optical arrangement is achieved by arranging the corners of the optical element facing the large chamfer. Can be prevented,
By inserting a housing into this chamfered portion, the holding of these optical elements can be facilitated, and four optical elements and means can be arranged at high density. As a result, the size and weight of the entire device can be further advanced, and the direction of installation can be easily recognized at the time of manufacture.

Also, the dielectric multilayer film of the color separation / combination means, for example, a dichroic coat is inclined at a predetermined angle to the optical axis in the color separation / combination direction with respect to the longitudinal direction of the surface of the dielectric multilayer film. It is configured to have a film. This makes it possible to control the wavelength band of color separation with respect to the color of light entering and exiting each color panel and to arrange a dielectric multilayer film for color separation such as an inclined film, so that color uniformity and color It is possible to increase the purity. With this configuration, the optical performance can be further improved.

In the optical engine of the present invention, the first light,
Separation means for separating the second and third lights, a first prism for guiding the first light to the first image display element, and a second and third light for separating the second and third lights from each other. A second prism for guiding to the image display element; and a combining unit for combining the first to third lights, and a first prism on one of the first prism surfaces from which the first light enters and exits. A color adjustment film is provided, and a second color adjustment film is provided on one of the surfaces on which the second and third lights enter and exit. In the present invention, the synthesizing means is a third prism, and one of the first prism surface on which the first light enters and exits and the third prism surface on which the first light enters. The first color adjusting film is provided on the surface of the second prism surface and the second prism surface from which the second light and the third light enter and exit, and the second light and the third light enter the third prism surface. The second color adjustment film is provided on one of the surfaces of the third prism surface. Further, a polarization conversion element is provided on one of the optical path of the first light and the optical path of the second light, and the color is adjusted by the color adjustment film and the polarization conversion element.

Further, in the optical engine of the present invention, the separation means for separating the first light, the second light and the third light,
A first polarizing beam splitter for entering the light into the image display element and analyzing the light, and a second polarizing beam splitter for entering the second and third light display elements and analyzing the light. A polarizing beam splitter, combining means for combining the first to third lights, and a polarization conversion element provided in an optical path of the first light and one of the second and third optical paths. And the color is adjusted by the separating means and the polarization conversion element. In the present invention, first and second specific wavelength band polarization conversion elements are provided on the input / output surface of the second polarization beam splitter, respectively.
The color is adjusted by the separating means and the first and second specific wavelength band polarization conversion elements. Further, the half value of the separating means and the half value of the first and second specific wavelength band polarization conversion elements are combined to cut off light near 500 nm.

According to another invention of the optical engine, the color separation means and the first light separated by the color separation means are made incident on the first image display element, and the light from the first image display element is emitted therefrom. A first prism that emits light and a first prism that is separated by the color separation unit.
And the second light are incident on the second and third video display elements,
A second light source for emitting light from the second and third video display elements;
And a color synthesizing means for synthesizing the first to third lights, and a polarizing plate arranged near at least one of the first and second prisms, wherein the polarizing plate Is attached to a nearby prism. In the present invention,
The color synthesizing means is composed of a prism, and a polarizing plate disposed near the prism is attached to the prism.

In the optical engine of the present invention, the light separated by the color separation means is modulated by the image display element, synthesized by the color synthesis means, and emitted by the emission means. Is constituted by one of a dichroic mirror and a dichroic prism, and the color synthesizing means is constituted by one of a dichroic mirror and a dichroic prism, and a half-value wavelength of the color separating means and a half-value wavelength of the color synthesizing means are set to different values. To improve the color purity.

Further, in the optical engine of the present invention, in an optical engine using a dichroic element comprising a dichroic mirror or a dichroic prism, a dichroic coat is provided on the dichroic element, and the thickness of the dichroic coat is changed according to the incident angle of light. Let it.

In the optical engine of the present invention, in an optical engine using a prism composed of a polarizing beam splitter or a dichroic prism, the glass material is changed according to the use of the prism.

Also, the optical engine of the present invention includes a color separating means, a polarizing beam splitter for light detection, and a color synthesizing means, and one of the color separating means and the color synthesizing means includes a polarizing beam splitter or a dichroic prism. In the optical engine using the prism, the polarization beam splitter for the analysis and the glass material of the prism are changed depending on the application, and the volume of the prism is made smaller than the volume of the polarization beam splitter for the analysis.

Further, in the optical engine of the present invention, a liquid crystal display element having a frame filled with liquid crystal and a cover glass of the liquid crystal is directly bonded to a prism composed of a polarizing beam splitter or a dichroic prism.

Further, in the optical engine of the present invention, a liquid crystal display element having a frame for filling a liquid crystal and a cover glass for the liquid crystal is provided by bonding an adjusting plate to a prism comprising a polarizing beam splitter or a dichroic prism. Glue.

Further, in the optical engine of the present invention, in the optical engine having a prism formed by bonding the first prism piece and the first prism piece, the length of the first prism piece is changed to the second prism piece. And bonding the first and second prism pieces so as to provide a step between the first and second prism pieces. A plurality of combined prisms are provided, and positioning between the plurality of prisms is performed using the stepped portion. In the present invention, the base for mounting the first prism piece and the second
And a second base portion on which the prism pieces are mounted. The plurality of prisms are attached to the assembly bracket. The prism provided on the optical path through which light enters the liquid crystal display element is arranged such that the light incident side is the second prism piece and the light exit side is the first prism piece. The prisms provided on the optical path emitted from the display element are arranged such that the light incident side is the first prism piece and the light emitting side is the second prism piece.

Also, in the optical engine of the present invention, the prism formed by bonding the first prism piece and the second prism piece, the liquid crystal display element arranged near the prism, An optical engine having a wavelength plate disposed between liquid crystal display elements, wherein the length of the first prism piece is shorter than the length of the second prism piece, And the first prism piece and the second prism piece are attached to form a prism having a step portion so that a step portion is provided between the second prism piece and
The wave plate is adjusted with reference to a surface of the first prism that is in contact with the step.

In the optical engine of the present invention, the light separated by the color separation means is modulated by the image display element, synthesized by the color synthesis means, and emitted by the emission means. The green light incident on the S-polarized light is the S-polarized light, and the red light and the blue light are the P-polarized light. I do.

In the optical engine of the present invention, the light separated by the color separation means is modulated by the image display element, synthesized by the color synthesis means, and emitted by the emission means. The green light incident on is a P-polarized light, the red light and the blue light are S-polarized light, and the emission optical axis of the image display device for modulating the green light and the emission optical axis of the color synthesizing means are substantially parallel to each other. It is configured to

In the optical engine of the present invention, the light separated by the color separation means is modulated by the image display element, synthesized by the color synthesis means, and emitted by the emission means. And first and second video display elements arranged substantially orthogonal to each other in proximity to the color separation / combination means, and the light incident on the color separation / combination means is transmitted to the first
And the second light and the second light, respectively.
And the optical axis of the output light of the color separation / combination unit that combines the first and second lights obtained from the first and second video display elements is the color separation. The color separation / combination unit is configured so that its optical axis is substantially perpendicular to the optical axis of the light incident on the combination unit and the optical axis of the emission unit.

In the optical engine of the present invention, the light separated by the color separation means is modulated by the image display element, synthesized by the color synthesis means, and emitted by the emission means. A color separation / combination unit including the color separation unit, the image display unit, and the color combination unit, and is incident on the color separation / combination unit and emitted from the optical axis of light and the color separation unit. The light emitted from the color separation / combination unit is converted into an optical axis by the optical axis conversion means and is incident on the projection means. Further, the projection type image projection apparatus using these optical engines includes a screen provided with a lens for making the optical axis parallel, and an optical axis conversion means for changing the optical axis of the light emitted from the projection means, The optical axis of the light emitted from the projection means is converted and projected on the screen.

In the optical engine according to the present invention, the light separated by the color separating means is modulated by the image display element, synthesized by the color synthesizing means, and emitted by the emitting means. , A condenser lens is provided, and the first focal point of the condenser lens is located near the stop surface of the projection means.

Further, the image display device is configured using the optical engine described above.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the drawings by using some examples.

FIG. 1 is a schematic plan view showing a first embodiment of the projection type liquid crystal display device according to the present invention. The embodiment of FIG. 1 uses a reflective liquid crystal display element 2 as a liquid crystal light valve,
This shows a three-panel projection display apparatus using a total of three pieces corresponding to three primary colors R (red), G (green), and B (blue). In FIG. 1, a projection type liquid crystal display device has a light source 1, and the light source 1 is a white lamp such as an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp, a mercury xenon lamp, and a halogen lamp. Light source 1
At least one reflecting mirror 5 having a circular or polygonal exit aperture, and light emitted from the light source 1 passes through a liquid crystal display element 2, which is a light valve element, toward a projection lens 3, and is projected on a screen 4. .

The light radiated from the bulb of the light source 1 is condensed by an elliptical, parabolic or aspherical reflector 5, and
It is constituted by a plurality of condenser lenses provided in a rectangular frame having substantially the same size as the exit aperture of the reflecting mirror 5,
The light emitted from the lamp unit is condensed and is incident on a first array lens 6 for forming a plurality of secondary light source images, and is further constituted by a plurality of condensing lenses. It passes through a second array lens 7 which is arranged in the vicinity of where the image is formed and forms the individual lens images of the first array lens 6 on the liquid crystal display element 2. The emitted light is incident on a row of rhombic prisms each having a size approximately half the width of each lens and arranged so as to match the lateral pitch of each lens optical axis of the second array lens 7. The prism surface is coated with a polarizing beam splitter 8, and the incident light is reflected by the polarizing beam splitter 8.
Is separated into P-polarized light and S-polarized light. The P-polarized light goes straight through the polarization beam splitter 8 as it is, and the polarization direction is rotated by 90 ° by the λ / 2 wavelength plate 9 provided on the exit surface of the prism, and is converted to S-polarized light and emitted. . On the other hand, the S-polarized light is reflected by the polarizing beam splitter 8, reflected again in the original optical axis direction in the adjacent rhombic prism, and emitted as S-polarized light. The emitted light is incident on the collimator lens 10.

In a conventional projection type liquid crystal display device using a reflection type liquid crystal display element, only the polarized light in one direction is reflected by the combination of the incident polarizer and the reflection liquid crystal display element, so that the amount of reflected light is reduced to about half. . However, since the polarization beam splitter 8 is used, the polarization direction of the randomly polarized light emitted from the light source 1 is incident on the reflection type liquid crystal display element 2 with the polarization direction aligned, and is ideally twice that of the conventional projection type liquid crystal display device. Brightness is obtained. The array lenses 6 and 7 act so that the individual images of the respective lens cells overlap the liquid crystal display element 2 and uniform image quality is obtained.

The collimator lens 10 has at least one or more components, has a positive refractive power, has the function of further condensing this S-polarized light, and
The light passing through 0 is converted by the reflection mirrors 11 and 12 in the optical axis direction by 90 ° in a predetermined direction. After that, the light passes through the condenser lens 30 and irradiates the three reflective liquid crystal display elements 2R, 2G, and 2B for each color RGB first by the color separation mirror 13 or a color separation prism (not shown). A polarization beam splitter 16 which is divided into two light beams and R and B light beams and is a polarization conversion device dedicated to each color.
G, 16 RB. That is, the G light is incident on the G-only polarizing beam splitter 16G of the present invention, and thereafter is S-polarized light, is reflected toward the G-only reflective liquid crystal display element 2G, and irradiates this panel. Further, the B light and the R light pass through the polarizing plate 14 exclusively for the BR light, and
The light enters the dedicated polarization beam splitter 16RB, and then passes through a specific wavelength band polarization conversion element 17 that changes the polarization direction only in a specific wavelength band to convert either the B light or the R light into S light.
The B light, which is the P-polarized light whose polarization has been converted from the polarized light to the P-polarized light, for example, passes through the RB-dedicated polarizing beam splitter 16RB, and the B-dedicated reflective liquid crystal display element 2
Irradiate B. On the other hand, since the R light is the S-polarized light, the R light is reflected by the RB dedicated polarization beam splitter 16RB, and then irradiates the R dedicated reflective liquid crystal display element 2R. Of course, the above example is one specific example, and the embodiment is not limited to this. R may be converted to P-polarized light, and separately from this, the polarized light of the original illumination system is P-polarized light. Yes, RG
The configuration also holds when one color of B is converted to S-polarized light and the remaining two colors are P-polarized light. On the incident side of the reflective liquid crystal display elements 2R, 2G, and 2B dedicated to each color, an RB-specific incident polarizer 14 and a G-specific incident polarizer 15 that transmit S-polarized light are arranged, and the degree of polarization and color purity of each color are arranged. Can also be increased. After that, the polarization is converted by the reflection type image display device 2 dedicated to each color, the light is again incident on the polarization beam splitters 16G and 16RB dedicated to each color, the S-polarized light is reflected, and the P-polarized light is transmitted.

The reflection type video display element 2 corresponds to a pixel to be displayed (for example, 1024 pixels in width and 3 pixels in 768 pixels).
(For example, colors). Then, the polarization angle of each pixel of the liquid crystal display element 2 changes according to a signal driven from the outside, and finally light that is orthogonal to the incident polarization direction is emitted, and the light whose polarization direction matches the polarization beam The light is analyzed by the splitter 2. The amount of light passing through the polarization beam splitter and the amount of light to be detected are determined for the light having the polarization at an intermediate angle depending on the degree of polarization of the polarization beam splitter 2. In this way, an image is projected according to a signal input from the outside. At this time, the polarization conversion elements, which are the G-dedicated polarizing beam splitter 16G and the RB-dedicated polarizing beam splitter 16RB, of the present invention, when the reflective image display elements 2R, 2G, 2B perform black display, the polarization direction is It is equivalent to light, and is returned to the light source side along the incident light path. However, the degree of polarization of the polarizing beam splitter and the analysis efficiency, which is the extinction ratio, slightly affect the performance,
The slightly leaked or disturbed polarized light passes through the polarizing beam splitter, passes through the color combining mirror 19 or the color combining prism on the exit side, and is irradiated to the projection lens 20 side,
At the time of black display, a slight brightness is detected on the screen.
As a result, the contrast performance may decrease.

Naturally, the dielectric multilayer film constituting the polarization conversion element and the color separation / combination prism has a function of transmitting or reflecting P-polarized light and S-polarized light with respect to light of a specific wavelength band incident thereon. A structure in which a dielectric multilayer film dedicated to a limited wavelength range is applied so that the transmission efficiency or reflection efficiency of the light or the transmission efficiency or reflection efficiency for circularly polarized light takes a peak value. G polarization beam splitter 16 with an optimal dielectric multilayer coating for G light in the band
G, from 400nm to 500nm, 600n
By using an RB dedicated polarization beam splitter 16RB provided with an optimal dielectric multilayer film dedicated to R light and B light in two or more wavelength bands from near m to near 700 nm, The film can be easily attached, and the transmission efficiency, the reflection efficiency, and the above-mentioned detection efficiency are also improved as compared with the related art. For this reason, high-precision color reproducibility and high brightness,
It is possible to provide a reflective liquid crystal display device that achieves high efficiency contrast and the like. Furthermore, by adding an inclined film, that is, a film in which the thickness of the dielectric multilayer film is changed depending on the incident angle of light, an image with higher uniformity and higher color purity can be displayed.

The light emitted from the polarization beam splitter 16 RB is converted into R light or B light by a specific wavelength band polarization conversion element 18.
One of the polarization directions of the light is converted, and both the R light and the B light are converted into, for example, S-polarized light, and then incident on the dichroic mirror 19. Thereafter, the light of each color of RGB, which is an image, is color-combined again by a color combining mirror 19 such as a dichroic mirror or a dichroic prism (not shown). Pass 20 and reach the screen. The reflection type liquid crystal display element 2 is
The images formed on R, 2G, and 2B are enlarged and projected on a screen and function as a display device. This 3
In a reflection type liquid crystal display device using two reflection type liquid crystal display elements, a power supply 21 drives a lamp, a panel, and the like.

Therefore, in the conventional reflection type liquid crystal display device,
After the light of the light source is separated into RGB three-color lights by at least one or more color separation prisms or color separation mirrors, each of the RGB color lights is analyzed by at least three or more polarization beam splitters, and further, by a color synthesis prism. Since images were projected onto the screen by the projection lens after combining the three colors, the entire apparatus tended to be large, heavy, and expensive. The configuration using two polarizing beam splitters exclusively for G and RB according to the present invention can achieve a reduction in size and weight, can further freely control color purity, further improve color unevenness, and improve performance. Can be realized at the same time. Accordingly, a compact, high-brightness, high-quality projection-type image display device can be realized. Further, since the number of parts can be reduced, cost reduction can be achieved.

FIG. 2 is a schematic plan view showing a second embodiment according to the present invention. Reflective image display elements 2R, 2G,
2B, for example, a reflection type liquid crystal display device, a reflection type ferroelectric image display device, a driving micromirror image display device, or the like, and is analyzed by a polarization conversion element which is a polarization beam splitter 16G and a polarization beam splitter 16RB. Light of each color of RGB, which is an image, is again color-combined by the dichroic dich prism 19a, and the light passes through a projection unit 20 such as a zoom lens, for example.
Reach the screen. The images formed on the reflective liquid crystal display elements 2R, 2G, and 2B by the projection means 20 are enlarged and projected on a screen to function as a display device. The prism 19a of the present invention has a size larger than that of the polarizing beam splitter so that light rays are not vignetted, and has a configuration different from that of the polarizing beam splitter in order to reduce the overall configuration. . In addition, since the inclined film and the like can be freely set independently by the dichroic coating, it is possible to provide an image with uniform high color purity.

Further, according to the configuration of the present invention, an optical element such as the dichroic prism 19a is provided with a support for the chamfered portion 29 in the housing, and the chamfered portion 29 of the optical element is supported by this. Dichroic prism 1
This facilitates holding and positioning of the optical element 9a, shortens the assembling time during mass production, and also reduces the cost of the entire projection type video display device. In addition, the corner chamfer 29 allows another optical member, for example, a lens or another optical element, to be arranged in a space allowance, and avoids mutual interference in a high-density arrangement, thereby achieving downsizing.

FIG. 3 is a plan view showing a third embodiment according to the present invention. The illuminating light passes through the condenser lens 30, and the three color RGB reflective liquid crystal display elements 2R, 2G,
In order to irradiate 2B, first, a specific wavelength band polarization conversion element 2
In step 8, the polarization direction of light in a predetermined wavelength band is changed. In this case, if the illuminating light is S-polarized light, it is converted to P-polarized light, and is separated into each color light by the broadband polarizing beam splitter 16RGB. For example, when the polarization of the G light is converted by the specific wavelength band polarization conversion element 28, the polarization beam splitter 16RGB
Is divided into G light, R light, and B light by a polarization beam splitter 16G, which is a polarization conversion element dedicated to each color.
It is incident on 16RB. That is, the G light converts the polarization direction of the P-polarized light into the S-polarized light by the specific wavelength band polarization conversion element 27 and enters the G-dedicated polarization beam splitter 16G. The light is reflected to the 2G side and irradiates the liquid crystal display element 2G. Also, B
The light and the R light pass through the B / R dedicated polarizing plate 14, enter the RB dedicated polarizing beam splitter 16RB, and then change the polarization direction only in a specific wavelength range.
7, and converts either the B light or the R light from the S-polarized light to the P-polarized light. B-only reflective liquid crystal display element 2B passing through splitter 16RB
Is irradiated. On the other hand, since the R light is the S-polarized light, the R light is reflected by the RB dedicated polarization beam splitter 16RB, and then irradiates the R dedicated reflective liquid crystal display element 2R.

Of course, the above example is one specific example, and the embodiment is not limited to this. R light may be converted to P polarized light, and separately from the polarized light of the original illumination system. Is P-polarized light, one RGB color is converted into S-polarized light, and the other two colors become P-polarized light, the configuration holds. In addition, R, which transmits S-polarized light, is provided on the incident side of the reflective liquid crystal display elements 2R, 2G, and 2B dedicated to each color.
It is also possible to arrange the B-only incident polarizer 14 and the G-only incident polarizer 15 to increase the degree of polarization and / or color purity of each color. Then, the reflective image display device 2 dedicated to each color
The light is again incident on the polarization beam splitters 16G and 16RB for each color, the S-polarized light is reflected,
P-polarized light is transmitted.

The reflection type image display element 2 corresponds to a pixel to be displayed (for example, 1024 pixels in width and 3 pixels in 768 pixels).
(For example, colors). Then, the polarization angle of each pixel of the liquid crystal display element 2 changes according to a signal driven from the outside, and finally light that is orthogonal to the incident polarization direction is emitted, and the light whose polarization direction matches the polarization beam The light is analyzed by the splitter 16. The amount of light passing through the polarization beam splitter 16 and the amount of light to be detected are determined for the light having the polarization at an intermediate angle in relation to the degree of polarization of the polarization beam splitter 16. In this way, an image is projected according to a signal input from the outside. At this time, the polarization conversion elements, which are the G-dedicated polarization beam splitter 16G and the RB-dedicated polarization beam splitter 16RB, have polarization directions equivalent to those of the incident light when the reflective image display elements 2R, 2G, and 2B perform black display. And is returned to the light source side along the incident optical path as it is. After that, the light of each color of RGB, which is an image, is recombined by the dichroic mirror 19 or a dichroic prism (not shown), and the light is
The light passes through a projection unit 20 such as a zoom lens and reaches a screen. By the projection means 20,
The images formed on the reflective liquid crystal display elements 2R, 2G, and 2B are enlarged and projected on a screen and function as a display device. In the reflection type liquid crystal display device using the three reflection type liquid crystal display elements, a power supply 21 drives a lamp, a panel, and the like.

Therefore, in the conventional reflection type liquid crystal display device,
After the light of the light source is separated into RGB three-color lights by at least one or more color separation prisms or color separation mirrors, each of the RGB color lights is analyzed by at least three or more polarization beam splitters, and further, by a color synthesis prism. Since images were projected onto the screen by the projection lens after combining the three colors, the entire apparatus tended to be large, heavy, and expensive. In the configuration using two polarizing beam splitters dedicated to G and RB according to the present invention, the size and weight can be reduced, the color purity can be freely controlled, the color unevenness and the like can be improved, and the performance can be improved. Can be realized at the same time. Further, since the color separation means is performed by a combination of the polarization beam splitter and the specific wavelength region polarization conversion element, the influence of the angle dependency is small, and the design of the color performance is facilitated. Therefore, a compact, high-brightness, high-quality projection-type image display device can be realized. Further, since the number of parts can be reduced, cost reduction can be achieved.

FIG. 4 is a plan view showing a fourth embodiment of the present invention. In addition to the effects of the embodiment of FIG. 3, each of RGB colors emitted from the reflection type image display elements 2R, 2G, and 2B and analyzed by the polarization conversion elements that are the polarization beam splitter 16G and the polarization beam splitter 16RB. Is combined again by the dichroic prism 19a, and the light passes through the projection means 20 and reaches the screen. The reflection type liquid crystal display element 2 is
The images formed on R, 2G, and 2B are enlarged and projected on a screen and function as a display device. The prism 19a of the present invention has a size larger than that of the polarizing beam splitter so that light rays are not vignetted, and has a configuration different from that of the polarizing beam splitter in order to reduce the overall configuration. . Further, since the inclined film and the like can be freely set independently by the dichroic coat, an image with uniform high color purity can be displayed.

Further, according to the structure of the present invention, an optical element such as the dichroic prism 19a is provided with a support for the chamfered portion 29 in the housing, and the chamfered portion 29 of the optical element is supported on the housing. Dichroic prism 1
This facilitates holding and positioning of the optical element 9a, shortens the assembling time during mass production, and also reduces the cost of the entire projection type video display device. In addition, the corner chamfered portion 29 arranges another optical member and the polarization beam splitter 16RGB, which is a polarization conversion element, in the space allowance, thereby avoiding mutual interference in a high-density arrangement, and achieving downsizing. . FIG. 5 is a plan view showing a fifth embodiment of the video display apparatus according to the present invention, and particularly shows the configuration of an optical system.

In FIG. 5, the image display device is provided with a light source unit including a light source 1 and a reflection reflector 2, and the light emitted from the light source unit passes through a polarization rectifying element 31, for example, a polarizing plate or a polarizing beam splitter (PBS). The light that has passed and is rectified as P-polarized light is
3, G light (green light), R light (red light) and B light
Separated into light (blue light). The separated G light is incident on the polarization beam splitter 16G, the incident light that is P-polarized light is transmitted, and is incident on the reflective liquid crystal display element 2G that is an image display element, and is subjected to polarization conversion according to an image signal and is reflected. Then, the light enters the polarization beam splitter 16G again. The polarization beam splitter 16G analyzes the incident light according to the amount of polarization conversion received by the reflection type liquid crystal display element 2G, that is, reflects only the S-polarized light component generated by receiving the polarization conversion from the incident light. And get the video.

The R light and the B light separated by the green separation mirror 13 are converted into only the R light into the S-polarized light by the specific wavelength band polarization conversion element 17 for changing the polarization direction of the specific wavelength band, and the polarization beam splitter 16RB is used. Is incident on.
The R light, which is the S-polarized light, is reflected by the polarizing beam splitter 16RB, and is incident on the reflective liquid crystal display element 2R. The light incident on the reflection type liquid crystal display element 2R undergoes polarization conversion according to the video signal and is reflected and is reflected by the polarization beam splitter 16R.
B is incident again. The polarization beam splitter 16RB analyzes light according to the amount of polarization conversion received by the reflective liquid crystal display element 2R to obtain an image. The B light is transmitted as P-polarized light through the polarization beam splitter 16RB, and is incident on the reflection type liquid crystal display element 2B. Reflective liquid crystal display element 2B
Incident on the polarization beam splitter 16RB undergoes polarization conversion according to the video signal, is reflected, and reenters the polarization beam splitter 16RB. The polarization beam splitter 16RB analyzes light according to the amount of polarization conversion received by the reflective liquid crystal display element 2B to obtain an image.

Although not shown in the drawing, only the B light may be converted into S-polarized light by the specific wavelength band polarization conversion element 17 for converting the polarization direction of the specific wavelength band. At this time, the polarization-converted B light becomes S-polarized light and is incident on the polarization beam splitter 16RB. The B light, which is the S-polarized light, is reflected by the polarizing beam splitter 16RB, and is incident on the reflective display element 2B. Reflective liquid crystal display device 2
The light incident on B undergoes polarization conversion according to the video signal, is reflected, and is incident again on the polarization beam splitter 16RB. The polarization beam splitter 16RB analyzes light according to the amount of polarization conversion received by the reflective liquid crystal display element 2B to obtain an image. The R light is transmitted through the polarization beam splitter as P-polarized light, and is incident on the reflective liquid crystal display element 2R. The light that has entered the reflective liquid crystal display element 2R undergoes polarization conversion according to the video signal, is reflected, and is again incident on the polarization beam splitter 16RB. The polarization beam splitter 16RB analyzes light according to the amount of polarization conversion received by the reflective liquid crystal display element 2R to obtain an image.

The red, blue and green images obtained respectively are synthesized by color synthesizing means 19, for example, a dichroic mirror or a dichroic prism, and the projection lens 20.
Is projected. At this time, if necessary, a specific wavelength band polarization conversion element 18 for converting the polarization direction of the specific wavelength band may be inserted on the exit side of the polarization beam splitter 16RB to align the polarization directions of the R light and the B light. At this time, R
By setting the wavelength range for polarization conversion of the specific wavelength range polarization conversion element 18 so that the polarization directions of all of the light, G light, and B light are aligned, it becomes possible to use a polarizing screen.

Alternatively, with respect to the light detected by the polarization beam splitter 16G in the optical path of the G light, the S-polarized light is
A polarization conversion element 32 for converting the light into polarized light is disposed so that the polarized light is incident on the color synthesizing means 19 such as a color synthesizing mirror as P-polarized light. Further, in the red and B light paths, one or both of the R light and the B light are provided. The polarization conversion wavelength band of the specific wavelength band polarization conversion element 18 for converting the polarization direction of the specific wavelength band is set so that the polarization direction of the light becomes the S-polarized light. This makes it possible to widen the transmission band of the G light and widen the reflection band of one or both of the R light and the B light by the polarization characteristics of the dichroic mirror or the dichroic coat as the color synthesizing means 19.

Further, polarization rectifiers 33, 34 and 35 may be arranged on the incident side and / or the exit side of the polarization beam splitter 16G and / or the polarization beam splitter 16RB. At this time, in the red and B optical paths, the polarization rectifying element 33 arranged before the polarization beam splitter 16RB enters the optical element 1 for changing the polarization direction in a specific wavelength range.
7 before the incidence. In addition, the polarization rectifying device 35 disposed after the incidence of the polarization beam splitter 16RB on the optical path of the red and B lights is disposed after the emission of the specific wavelength band polarization conversion element 18 for changing the polarization direction of the specific wavelength region. The configuration using two polarization beam splitters according to the present invention can achieve a reduction in size and weight, can further freely control color purity, and can improve color unevenness and the like.

FIG. 6 is a plan view showing a sixth embodiment of the video display device according to the present invention, and shows the configuration of the optical system. 6, the image display device has a light source unit including a light source 1 and a reflection reflector 5, and the light source 1 is a white lamp. The light emitted from the light source unit passes through a polarization rectifying element 8, for example, a polarizing plate or a polarization conversion element (polarizing beam splitter). And B light.

The separated G light is a polarized beam splitter 1
6G, the incident light as S-polarized light is reflected, enters the reflective liquid crystal display element 2G as an image display element, undergoes polarization conversion in accordance with an image signal, is reflected, and enters the polarization beam splitter 16G again. I do. Polarizing beam splitter 16
G analyzes light with respect to the incident light in accordance with the polarization conversion amount received by the reflection type liquid crystal display element 2G, that is, reflects only the P-polarized component generated by receiving the polarization conversion from the incident light, Get the picture.

The R light and the B light separated by the green separation mirror 13 are subjected to polarization conversion of only the R light into P-polarized light by a specific wavelength band polarization conversion element 17 for converting the polarization direction of a specific wavelength band, and a polarization beam splitter 16RB. Is incident on. The R beam, which is P-polarized light, is transmitted by the polarization beam splitter 16RB, and is incident on the reflection type liquid crystal display element 2R. The light that has entered the reflective liquid crystal display element 2R undergoes polarization conversion according to the video signal, is reflected, and enters the polarization beam splitter 16RB again. Polarizing beam splitter 16R
In B, light is analyzed according to the amount of polarization conversion received by the reflective liquid crystal display element 2R to obtain an image. The B light is reflected by the polarization beam splitter 16RB as S-polarized light, and enters the reflective liquid crystal display element 2B. The light incident on the reflective liquid crystal display element 2B undergoes polarization conversion according to the video signal, is reflected, and is incident again on the polarization beam splitter 16RB. The polarization beam splitter 16RB analyzes light according to the amount of polarization conversion received by the reflective liquid crystal display element 2B to obtain an image. Although not shown in the drawing, only the B light may be converted into P-polarized light by the specific wavelength band polarization conversion element 17 that converts the polarization direction of the specific wavelength band. At this time, the polarization-converted B light becomes P-polarized light,
The light enters the polarization beam splitter 16RB. The B light, which is the P-polarized light, is transmitted by the polarization beam splitter 16RB and is incident on the reflective liquid crystal display element 2B. The light incident on the reflective liquid crystal display element 2B undergoes polarization conversion according to the video signal, is reflected, and is incident again on the polarization beam splitter 16RB. The polarization beam splitter 16RB analyzes light according to the amount of polarization conversion received by the reflective liquid crystal display element 2B to obtain an image. The R light is reflected by the polarization beam splitter 16RB as S-polarized light, and is incident on the reflective liquid crystal display element 2R. The light that has entered the reflective liquid crystal display element 2R undergoes polarization conversion according to the video signal, is reflected, and is again incident on the polarization beam splitter 16RB. The polarization beam splitter 16RB analyzes light according to the amount of polarization conversion received by the reflective liquid crystal display element 2R to obtain an image.

The red, blue and green images obtained respectively are synthesized by the color synthesizing means 19, for example, a dichroic mirror or a dichroic prism, and projected by the projection lens 20. At this time, if necessary, a specific wavelength band polarization conversion element 18 for converting the polarization direction of a specific wavelength band is inserted into the exit side of the polarization beam splitter 16RB, and the R light, G light
By setting the wavelength range for polarization conversion of the specific wavelength range polarization conversion element 18 so that the polarization directions of all the light and the B light are made uniform, it becomes possible to use a polarizing screen.

Alternatively, at this time, in the optical paths of the R light and the B light, one or both of the polarization directions of the R light and the B light are changed to S.
The polarization conversion wavelength band of the specific wavelength band polarization conversion element 18 for changing the polarization direction of the specific wavelength band is set so as to be polarized light. This makes it possible to widen the transmission band of G light and widen the reflection band of R light and B light by the polarization characteristics of the dichroic mirror or dichroic coat as the color synthesizing means 19.

Further, the polarization rectifiers 33, 34, 35 may be arranged on the incident side or the exit side of the polarization beam splitter 16G and the polarization beam splitter 16RB. At this time, the polarization beam splitter 1
The polarization rectifying element 33 disposed before the incidence of 6RB is a specific wavelength band polarization conversion element 1 for changing the polarization direction of a specific wavelength band.
7 before the incidence. In addition, the polarization rectifying element 35 disposed after the incidence of the polarization beam splitter 16RB on the optical path of the R light and the B light is disposed on the light emission side of the specific wavelength band polarization conversion element 18 for changing the polarization direction of the specific wavelength band.

The configuration using two polarizing beam splitters according to the present invention can achieve small size and light weight,
Further, the color purity can be freely controlled, and color unevenness can be further improved.

FIG. 7 is a plan view showing a seventh embodiment of the projection display apparatus according to the present invention. In the embodiment of FIG.
Reflective liquid crystal display elements 2R, 2 as liquid crystal light valves
A three-panel projection display device using a total of three G and 2B corresponding to the three primary colors R (red), G (green) and B (blue) of the so-called colors is shown. In the projection type liquid crystal display device shown in FIG. 7, the light source 1 is a white lamp. Light emitted from the light source 1 is reflected by at least one reflecting mirror 5 having a circular or polygonal exit aperture, passes through liquid crystal display elements 2R, 2G, and 2B, which are light valve elements, toward a projection lens 20, and a screen. Projected to

Between the polarizing beam splitter 8 and the reflection type liquid crystal display element 2, dichroic which is a color separation means for transmitting or reflecting only the G light of the three primary colors of light, R light, G light and B light. A mirror 13 or a dichroic prism or the like is arranged, and is separated from other R light and B light. The G light separated by the dichroic mirror 13 is transmitted or reflected by the polarizing beam splitter 16G,
The light is incident on the liquid crystal display element 2G. At this time, polarizing plates 15 and 29 having a polarization rectifying effect on the G light may be disposed on the incident side and / or the exit side of the polarization beam splitter 16G. The light incident on the liquid crystal display element 2G is modulated as a readout light, reflected and emitted, and the modulated light is respectively analyzed by the polarization beam splitter 16G.
The R light and the B light separated from the G light are approximately 510n.
The light passes through a specific wavelength band polarization conversion element 17 that performs polarization conversion only in a band equal to or greater than or less than a specific wavelength from m to 580 nm, and the polarization of one of the R light and the B light changes. The polarization directions of the light and the B light are orthogonal. After that, the light enters the polarization beam splitter 16RB, where the R light and the B light having different polarization directions are separated, and are incident on the respective liquid crystal display elements 2R and 2B. At this time, a polarizing plate 14 having a polarization rectifying function may be provided on the incident side of the specific wavelength band polarization conversion element 17. In addition, a specific wavelength band polarization conversion element 18 that performs polarization conversion of only a band equal to or greater than or equal to a specific wavelength within approximately 510 nm to 580 nm may be disposed on the emission side of the polarization beam splitter 28RB. Further, at this time, a polarizing plate 29 having a polarization rectifying function may be arranged on the emission side of the specific wavelength band polarization conversion element 18.

The light incident on the liquid crystal display elements 2R and 2B is modulated and reflected and emitted as readout light by the liquid crystal display element corresponding to each color, and the modulated light of each color is output by the polarization beam splitter 16RB. It is analyzed. The detected R light, G light and B light are combined by a dichroic mirror 19 or a dichroic prism as a color combining filter, pass through a projection unit 20, and reach a screen. At this time, the light on the optical path that passes through the color synthesis filter becomes P-polarized light,
By setting the specific wavelength band polarization conversion element 18 so that the light on the optical path that reflects the color synthesis filter is S-polarized light, the transmission and reflection bands of the color synthesis filter are widened and a highly efficient optical system can be realized. The image formed on the liquid crystal display element 2 by the projection means 20 is enlarged and projected on a screen and functions as a display device. Further, since the polarizing plate is provided at the entrance and exit of the polarization beam splitter, the contrast can be improved.

The configuration using two polarizing beam splitters according to the present invention can achieve a reduction in size and weight, can further freely control color purity, can further improve color unevenness and the like, and can simultaneously improve performance. it can. Accordingly, a compact, high-brightness, high-quality projection-type image display device can be realized. Further, since the number of parts can be reduced, cost reduction can be achieved.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 8 is a schematic plan view showing an eighth embodiment of the projection type liquid crystal display device according to the present invention. In the figure, light from a light source (not shown) passes through a polarization conversion element 101 typified by a combination of a polarizing beam splitter prism and a half-wave plate, and P-polarized light is converted into S-polarized light. The light is emitted as it is as S-polarized light. As the polarization conversion element 101, an element that converts S-polarized light into P-polarized light may be used. In the present embodiment, a case where the P-polarized light is converted into S-polarized light by the polarization conversion element 101 will be described as an example. Polarization conversion element 10
G light of the S-polarized light transmitted through 1 is reflected by a color separation mirror 102 such as a dichroic mirror,
a, the light is incident on the polarization beam splitter 105G through the color adjustment film 104a. The polarizing plate 103a is used to remove the P-polarized light mixed with the S-polarized light which is the original light. The details of the color adjustment film 104a will be described later. The G light, which is the S-polarized light, is reflected by the polarizing beam splitter 105G, enters the reflective liquid crystal display device 107G through the １ ／ λ wavelength plate 106a, is reflected by the liquid crystal display device 107G, is converted into P-polarized light, and is polarized. Emitted from the splitter 105G, a polarization beam splitter for color synthesis or a dichroic prism 105R
It is incident on GB. The quarter-wave plate 106a is connected to the polarization axis of the liquid crystal display element 107G and the polarization beam splitter 1.
It is mainly used for aligning the polarization axes of the 05G and the illumination optical system.

The R light and the B light, which are the S-polarized light transmitted through the color separation mirror 102, are transmitted through the polarizing plate 103b for removing the P-polarized light and are incident on the specific wavelength band polarization conversion element 112a. In this embodiment, the specific wavelength band polarization conversion element 112a passes the R light as it is as the S-polarized light, and converts the B light from the S-polarized light to the P-polarized light. Specific wavelength band polarization conversion element 11
The R light and B light transmitted through 2a pass through the color adjustment film 104b and enter the polarization beam splitter 105RB. The R light, which is the S-polarized light, is reflected by the polarization beam splitter 105RB, passes through the λλ wavelength plate 106b, enters the reflection type liquid crystal display element 107R for R light, is reflected by the liquid crystal display element 107R, The light is again incident on the polarization beam splitter 105RB as polarized light, passes through the polarization beam splitter 105RB, and is incident on the specific wavelength band polarization conversion element 112b.

The B light converted into the P-polarized light passes through the polarizing beam splitter 105RB, and becomes a λλ wave plate 106c.
After that, the light enters the reflective liquid crystal display element 107B for B light, is reflected by the liquid crystal display element 107B, and is emitted as S-polarized light. The B light, which is the S-polarized light, is reflected by the polarization beam splitter 105RB and is incident on the specific wavelength band polarization conversion element 112b. The specific wavelength band polarization conversion element 112b converts the P light of the R light into the S polarized light, transmits the B light as the S polarized light, and the R light and the B light that are the S polarized light are the P polarized light of the B light. A polarizing beam splitter or a dichroic prism 10 for color synthesis through a polarizing plate 103c for removing light components and preventing deterioration of contrast.
It is incident on 5 RGB. G light which is P-polarized light is polarized beam splitter 105 or dichroic prism R
The R light and the B light, which are transmitted through GB and are S-polarized light, are polarized beam splitters or dichroic prisms 105.
The light is reflected by RGB and is incident on the projection lens 113. R
The P-polarized light component mixed into the light and the B light is transmitted in the case of the polarization beam splitter 105RGB. In the drawing, the solid line indicates S-polarized light, and the dotted line indicates P-polarized light.

In the embodiment shown in FIG. 8, the color separation mirror 1
Although the light incident on 02 is converted into S-polarized light, it may be configured to use light converted into P-polarized light. Further, the specific wavelength band polarization conversion element 112a converts the B light into P
Although converted to polarized light, it may be configured to convert R light to P-polarized light. As the color adjusting film 104, for example, a dielectric multilayer film directly deposited on a polarizing beam splitter or a dichroic prism, a dielectric multilayer film deposited on glass and adhered to a polarizing beam splitter or a dichroic mirror, a color It is a film, a color filter such as colored glass, or the like. In short, any material that can reduce the transmittance in a specific wavelength range can be applied.

Next, a ninth embodiment of the present invention will be described. FIG. 9 is a schematic plan view showing a ninth embodiment of the projection type liquid crystal display device according to the present invention. In the figure, the same components as those in FIG. 8 are described with the same reference numerals. In the figure, light from a light source (not shown) is converted by a polarization conversion element 101 into S-polarized light. The G light is reflected by the color separation mirror 102, passes through the polarizing plate 103a, is reflected by the polarizing beam splitter 105G, and enters the reflection type liquid crystal display element 107G through the ４λ wavelength plate 106a. The G light reflected by the liquid crystal display element 107G and converted into P-polarized light is transmitted through the λλ wavelength plate 106a and is incident again on the polarization beam splitter 105G, and the G light transmitted therethrough is transmitted through the color adjustment film 104a. Then, the light is incident on the λλ wavelength plate 115. G light, which is P-polarized light,
The light is converted into S-polarized light by the 2λ wavelength plate 115, and is polarized by a polarizing beam splitter or a dichroic prism 105RGB.
, Is reflected here, and is incident on the projection lens 113.

On the other hand, R transmitted through the color separation mirror 102
The light and the B light pass through the polarizing plate 103b and enter the specific wavelength band polarization conversion element 112a. The B light, which is the S-polarized light, is converted into the P-polarized light by the specific wavelength region polarization conversion element 112a, and the R light is incident on the polarization beam splitter 105RB for analysis as the S-polarized light. The R light, which is the S-polarized light, is reflected by the polarizing beam splitter 105RB, passes through the quarter-wave plate 106b, and enters the liquid crystal display element 107R. The R light reflected by the liquid crystal display element 107R is converted into P-polarized light, passes through the λλ wavelength plate 106b, and is incident on the polarization beam splitter 105RB again. The B light converted into the P-polarized light is a polarized beam splitter 105RB.
Through the を λ wavelength plate 106c, and is incident on the reflective liquid crystal display element 107B. The B light is reflected here, converted into S-polarized light, transmitted through the λλ wavelength plate 106c, again incident on the polarizing beam splitter 105RB, and reflected by the polarizing beam splitter 105RB. P
The R light as the polarized light and the B light as the S polarized light are
4b, and enters the specific wavelength band polarization conversion element 112b. B light, which is S-polarized light, is converted to P-polarized light,
The light passes through the polarizing plate 103c as it is as P-polarized light, passes through the polarizing beam splitter 105RGB, and enters a projection lens (not shown).

In the embodiment shown in FIG. 8 and FIG.
By selecting a wavelength band in which the wavelength of light is reduced in 04, color adjustment can be performed and color reproducibility can be improved. For example, the color adjustment film 104
A wavelength band in which the transmittance is reduced may be selected in a and 104b, and a good color may be obtained by lowering the transmittance in the yellow wavelength region and the cyan wavelength region. In the case of increasing the brightness, the yellow component may be increased. In this case, in order to maintain the white balance, the color can be adjusted by the color adjustment film 104 so as to cut cyan.

In the embodiment of FIG. 8, the color adjustment film 104a
Is provided on the G light incident surface of the polarizing beam splitter 105G, but may be provided on the G light emitting surface of the polarizing beam splitter 105G as shown in FIG. Further, the color adjustment film 104a is a polarization beam splitter 105 for color synthesis.
Alternatively, the same effect can be obtained by providing the dichroic prism RGB on the G light incident surface. In FIG. 8, the color adjustment film 104b is provided on the incident surface of the R beam and the B light of the polarization beam splitter 105RB for analysis, but as shown in FIG. It may be provided on the light and B light emission surfaces, or may be provided on the R light and B light incidence surfaces of the polarizing beam splitter or dichroic prism 105RGB for color synthesis. That is, the same effect can be obtained by providing the color adjusting film 104 on the light input / output surface of the polarizing beam splitter for analysis and the polarizing beam splitter for color synthesis or the dichroic prism. In the embodiment of FIGS. 8 and 9, the color separation mirror 102 such as a dichroic mirror and the specific wavelength band polarization conversion elements 112a and 112b are used.
Can be adjusted to perform color adjustment.

An example of this case will be described with reference to FIG. FIG. 10 is a spectral characteristic diagram showing the light transmittance. The horizontal axis represents the wavelength W and the vertical axis represents the light output P. FIG.
(A) is an output characteristic curve P of the dichroic mirror 102.
0, for example, at a half value of 500 nm to 600 n
dichroic mirror 1 so that light between m
02 is configured. Of the light transmitted through the dichroic mirror 102, as shown in FIG. 10B, light having a wavelength of S1 or less longer than 600 nm is converted from S-polarized light to P-polarized light, and light having a wavelength of wavelength S1 or more is A specific wavelength band polarization conversion element 1 so as to transmit S-polarized light.
The characteristic curve P1 of FIG. This light is reflected by the liquid crystal display element 107 and converted into polarized light, light having a wavelength up to S1 is converted into S-polarized light, and light having a wavelength equal to or longer than S1 is converted into P-polarized light. As shown in FIG.
The light having a wavelength of S1 or less remains S-polarized light without being polarized.
Specific wavelength region polarization conversion element 11 having characteristic curve P2 configured to change the above light from P-polarized light to S-polarized light
2b, the P-polarized light remains at wavelengths S2 to S1, so that the light in this area is polarized beam splitter 10
Since the light is not reflected by 5RGB but passes through as it is, it does not enter the projection lens. Thus, the wavelengths S1 to S
2 light can be cut off. Thus, the dichroic mirror 102 and the specific wavelength band polarization conversion element 1
The transmittance of a specific region of the wavelength can be changed by the combination of 12a and 112b.

Similarly, the specific wavelength band polarization conversion element 11
2 and the configuration of the color adjustment film 104 can be changed to improve the brightness. For example, in order to improve brightness by inserting bright line light, the half value of the color adjustment film 104 and the half value of the specific wavelength band polarization conversion element 112 are combined to cut light near 500 nm, for example, light of 500 nm to 515 nm, and to reduce the bright line. Light with a wavelength of around 580 nm can be introduced to improve brightness and white balance.

A similar effect can be obtained by combining the dichroic mirror 102 and the color adjusting film 104. In this embodiment, the dichroic mirror 102 can be replaced with a dichroic prism. Therefore, in the above description, the dichroic mirror 102 can be replaced with a dichroic prism.

In the embodiment shown in FIG. 8 and FIG.
3a is provided in the vicinity of the polarizing beam splitter 105G, and the polarizing plate 103c is provided in the polarizing beam splitter 105RG.
B is provided in the vicinity. When these polarizing plates 103 are attached to a nearby polarizing beam splitter, interfaces can be reduced and light transmittance can be increased. Further, the polarizing beam splitter 105 has a large heat radiation effect and absorbs heat of the polarizing plate 103, so that the cooling property of the polarizing plate 103 can be enhanced. The optical engine shown in FIGS. 8 and 9 can be configured by a dichroic prism. in this case,
The polarizing plate 103 may be attached to the dichroic prism. In this case, it is preferable that the polarizing plate 103 be formed of a film.

In the embodiment shown in FIGS. 8 and 9, when a color adjusting film is provided on the incident surface of the dichroic mirror 102, for example, when a dielectric multilayer film is deposited, the thickness of the portion where the incident angle of light is large is increased. When the film thickness is changed so that the thickness of the portion where the incident angle of light is small becomes smaller, the value of the half-value wavelength shifts, and the color and color unevenness of the emitted light can be adjusted.

When the optical engine shown in FIGS. 8 and 9 is constituted by a dichroic mirror or a dichroic prism, that is, the color separation mirror 102 is constituted by a dichroic mirror or a dichroic prism, and the dichroic prism is used instead of the polarization beam splitter 105. When the color adjusting film is provided on these incident surfaces with different thicknesses, the same effect can be obtained.

In the embodiments shown in FIGS. 8 and 9, it is preferable to change the glass materials of the analyzing polarization beam splitters 105G and 105RB and the color combining polarization beam splitter 105RGB. For example, the analyzing polarization beam splitters 105G,
5RB is an analysis polarization beam splitter 105G, 105R.
For B, for example, a glass material having a small amount of birefringence such as PBH53W is selected, and for the synthetic polarization beam splitter 105RGB, a light and low-cost glass material such as BK7 is selected, thereby optimizing performance and reducing cost. Weight and weight reduction can be achieved.

The same applies to the case where the color separation mirror 102 is constituted by a dichroic prism or a polarizing beam splitter, and the polarizing beam splitter 105 is replaced by a dichroic prism. In this case, a light and low-cost glass material may be used as the dichroic prism for separation, similarly to the polarization beam splitter or the dichroic prism for synthesis.

In FIGS. 8 and 9, the capacity of the polarizing beam splitters 105G and 105RB for analysis is V1, and the capacity of the polarizing beam splitter 105RGB for color synthesis is V1.
In the case of 2, if V1 is made smaller than V2 and a glass material is selected as described above, the performance can be optimized according to the use characteristics, a low-cost glass material can be used, and the weight can be reduced. As a modification, the present invention can be applied to a case where a dichroic prism is used for a dichroic mirror for color separation, and a dichroic prism is used instead of the polarization beam splitter 105. In particular, when the size of the polarizing beam splitter 105RGB for color separation and color synthesis and the size of the dichroic prism are increased, it is possible to prevent the incoming and outgoing rays from being vignetted. In this case, by changing the glass material of the polarizing beam splitter or dichroic prism for the purpose of use such as the transmission efficiency or the reflectance of the glass material, performance improvement, cost reduction, and weight reduction by using a light-weight glass material are achieved. I can aim. For example, the analyzing polarization beam splitter has a high refraction and a light elastic constant of 0.5 × 10 ⁻¹² N.
/ M ² , size □ 32 and stress of 5.3 × 10 ⁴ or less Pa or less make the extinction ratio good, but dichroic prisms and polarizing beam splitters for color separation and color synthesis have low specific gravity. If a glass material having a high overall transmission efficiency including a dielectric multilayer film is used, even if the volume is increased to prevent vignetting of light rays, it is possible to improve performance, reduce weight, and reduce cost.

Next, an example in which the liquid crystal display element is mounted on the polarizing beam splitter 105 will be described with reference to FIG. FIGS. 11A and 11B are partial cross-sectional plan views showing an embodiment of how to attach a liquid crystal display element to a polarizing beam splitter. In FIG. 11A, a liquid crystal material 132 is sealed in a frame 107 of a liquid crystal display element 107G, and cover glasses 133a and 133b are provided on both sides of the frame. After adjusting the position of the liquid crystal display element 107G, the frame 13
The zero portion is directly bonded to the polarizing beam splitter 105G with adhesives 134a and 134b. The adhesive may be cured using, for example, a UV adhesive or a thermosetting adhesive. In this embodiment, the cover glass 133a and the polarizing beam splitter 105G may be bonded or fixed with an adhesive.

FIG. 11B shows another embodiment.
In this embodiment, an adjusting plate 134 is provided, and the adjusting plate 134 is bonded to the polarizing beam splitter 105G with an adhesive 134. After the position of the liquid crystal display element 107G is adjusted with respect to the polarization beam splitter 105G,
The frame 130 is bonded or fixed to the adjustment plate 134. Further, the cover glass 133a and the polarization beam splitter 10
An air layer can be eliminated by using silicone oil or an adhesive between 5G.

According to this embodiment, the interface between the polarizing beam splitter 105G and the liquid crystal display element 107G can be reduced, so that the light use efficiency can be improved.
In the embodiment shown in FIG. 11, the polarization beam splitter 10
Although the description has been given by taking the liquid crystal display elements for 5G and G light as an example,
Similarly, the liquid crystal display elements 107R and 107B for R light and B light can be provided with the same effect by directly attaching them to the polarizing beam splitter 105RB.

Next, the assembly of the polarization beam splitter will be described with reference to FIG. FIG. 12A is a perspective view showing one embodiment of the polarizing beam splitter, and FIG.
(B) is a perspective view showing an embodiment of an assembly structure of the polarizing beam splitter. In the present embodiment, a configuration using four prisms, in which the color separation mirror 102 shown in FIG. 8 is a polarizing beam splitter or a dichroic prism, is shown.

In FIG. 12A, reference numeral 151 denotes a polarizing beam splitter or dichroic prism for color separation, and a long triangular prism 151H and a short triangular prism 151 are provided to provide a step on the bonding surface.
L. Reference numeral 152 denotes a G light polarization beam splitter, which includes a long triangular prism 152H and a short triangular prism 152L in order to provide a step on the bonding surface. Reference numeral 153 denotes a polarizing beam splitter for R light and B light, and a long triangular prism 153H for providing a step on the bonding surface.
And a short triangular prism 153L. The light is color-separated by a polarization beam splitter 151 for color separation or a dichroic prism, and the G light is a polarization beam splitter or dichroic prism 152.
And is incident on the G light liquid crystal display element 107G.
The G light reflected by the liquid crystal display element 107G is reflected by a polarization beam splitter 154 for color synthesis and is incident on a projection lens (not shown). The R light and the B light separated by the polarization beam splitter 151 are
3 and the liquid crystal display elements 107R and 107R, respectively.
7B. The R light and the B light reflected by the liquid crystal display elements 107R and 107B pass through a polarization beam splitter 154 for color synthesis and enter a projection lens (not shown). A polarizing plate, 1 /
A 2λ wavelength plate, a specific wavelength band polarization conversion element, and the like are inserted.
By combining a long triangular prism and a short triangular prism, step portions 155 are provided above and below the polarizing beam splitters 151 to 154, respectively. FIG.
In (b), reference numeral 157 denotes an assembling structure, and a base 158 on which long triangular prisms 151H to 154H are mounted.
H-161H and short triangular prism 151L-15
There are provided bases 158L to 161L on which 4L is placed. The projection 163 provided on the assembly structure 157 is used for positioning.

In order to assemble the polarization beam splitter shown in FIG. 12A into the assembly structure 157, the bottoms of the long triangular prisms 151H to 154H are attached to the bases 158H to 161H.
The prisms 151L to 154L having a short triangular prism are arranged so as to be in contact with the positioning protrusions 163, and the bases 158L
To 158L so as to be in contact with the positioning projection 163. A groove is provided between the polarization beam splitters 151 to 154, and a polarizing plate, a specific wavelength band polarization conversion element, and the like are arranged. At this time, if the positioning is performed by a spring, a foam, or the like, the positioning can be performed with high accuracy. In this embodiment, steps are provided in the polarization beam splitters 151 to 154, and positioning is performed at these steps, so that the surface of the dielectric multilayer film of the polarization beam splitter serves as a reference plane, and assembling accuracy is improved. Therefore, the performance is also improved.

As is clear from the drawing, in this embodiment, the polarizing beam splitter 151 for color separation increases the area of the prism 151H on the light incident side, and the polarizing beam splitter on the output side, that is, the color synthesizing beam splitter 151. The area of the exit side prism 154H of the polarization beam splitter is increased. Until the light reaches the liquid crystal display element, it is preferable to reduce the light transmission area as it goes earlier, and the light emitted from the liquid crystal display element is set so that the transmission area becomes larger as it goes earlier. It is preferable to prevent vignetting of light. In this embodiment, such an effect can be achieved. In FIG. 12, it is needless to say that a similar effect can be obtained even when some of the polarization beam splitters are constituted by dichroic prisms.

Next, the adjustment mechanism of the λλ wavelength plate will be described with reference to FIG. FIG. 13 is a side view for explaining the mounting of the λλ wavelength plate. In the figure, 1
Reference numeral 60 denotes a mounting plate for the λλ wavelength plate 106a, which is provided with a window through which light from the polarizing beam splitter 142 passes. The quarter-wave plate 106a is fixed to the shaft 161. The shaft 161 is rotatably mounted on the mounting plate 160, adjusted so that the polarization axis of light with the liquid crystal display element 107G is aligned, and fixed to the mounting plate 160 after adjustment. The center of the rotation axis of the λλ wavelength plate 106a is positioned in accordance with the upper surface of the prism 152L. That is, the ４λ wavelength plate 106a is based on the upper surface or the lower surface of the polarizing beam splitter 152, or the exit side or the left and right surfaces. Therefore, even when the liquid crystal display element is replaced, the reference is constant and the original position is clear, so that the adjustment procedure can be clarified. The above embodiment is another one.
It goes without saying that the present invention can be applied to the mounting of a / 4λ wavelength plate.

In FIGS. 8 and 9, each of the polarization beam splitters 105G, 105RB, and 105RGB has a surface that does not contribute to the transmission or reflection of light. Alternatively, it is preferable that the surface not used for reflection is made of frosted glass or painted black. The same applies when the polarizing beam splitter is replaced with a dichroic prism.

Referring to FIG. 9, G light incident on polarizing beam splitter 105RGB for color synthesis is S-polarized light, RB light is P-polarized light, and light emitted from liquid crystal display element 107G for G light. The axis and the output optical axis of the polarization beam splitter 105RGB for color synthesis are arranged at right angles. A dichroic mirror or a dichroic prism can be used instead of the polarization beam splitter RGB for color synthesis.

When a dichroic mirror or a dichroic prism is used instead of the color combining polarizing beam splitter 105RGB shown in FIG. 9, the reflected light is combined with other light in the color combining dichroic mirror or dichroic prism. S-polarized light is more efficient for light, and conversely, P-polarized light is more efficient for light combined as transmitted light. That is, when the reflected light is the S-polarized light, the reflection bandwidth of the dielectric multilayer film provided on the dichroic mirror or the dichroic prism is widened, and it is hard to be affected by the film characteristics due to band shift or the like. When the transmitted light is P-polarized light, the transmission bandwidth of the dielectric multilayer film provided on the dichroic mirror or the dichroic prism is widened, and the film characteristics are hardly affected by band shift or the like. Therefore, it is efficient if the G light is reflected as S-polarized light, combined with P-polarized light transmitted through the dichroic mirror or the dichroic prism, and emitted in the optical axis direction reflected by the dichroic mirror or the dichroic prism.

On the other hand, the polarization beam splitter 1 for color synthesis
When 05RGB is used, when the light from the G liquid crystal display element 107G is configured to be reflected by the polarization beam splitter 105RGB and combined with the RB light and emitted, naturally, the reflected light is S-polarized light and the transmitted light is It is necessary to use P-polarized light.

In FIG. 8, the G light entering the polarizing beam splitter 105RGB, which is a color combining means, is P-polarized light, the RB light is S-polarized light, and The output optical axis of the polarizing beam splitter 105RGB as the output means is provided so as to be parallel to the output light of the above.

The polarization beam splitter 105 RGB of FIG.
Instead, a dichroic mirror or a dichroic prism can be used. In this case, the light transmitted through the dichroic mirror or dichroic prism for color synthesis is efficiently P-polarized light. On the other hand, the light combined with the transmitted light as reflected light is more efficient with S-polarized light. That is, when the transmitted light is P-polarized light, the bandwidth of the dielectric multilayer film provided on the dichroic mirror or the dichroic prism becomes wider, and the film characteristics are less affected by band shift and the like. Similar effects can be obtained when the reflected light is S-polarized light.

Therefore, G light is transmitted as P-polarized light, and RB
It is efficient if the light is reflected as a S-polarized light by a dichroic mirror or a dichroic prism, these lights are combined, and emitted in the direction of the optical axis passing through the dichroic mirror or the dichroic prism as the color combining means.

As shown in FIG. 8, when the polarizing beam splitter 105RGB is used as the color combining means,
In a configuration in which light from the liquid crystal display element 107G for G light is transmitted as light and combined with reflected light by the polarization beam splitter 105RGB and emitted, the transmitted light is naturally P-polarized light, and the R light and B light are S-polarized light. It needs to be light.

Referring to FIG. 9, the liquid crystal display element 107R for R light and the liquid crystal display element 107B for B light are disposed at a substantially right angle, and a polarization beam for separation / combination for separating and combining R light and B light. The input optical axis and the output optical axis of the splitter 105RB are substantially perpendicular to each other, and the projection lens 113 is arranged substantially parallel to the output optical axis. In the present embodiment, a polarization beam splitter 105R for separation / synthesis is used.
It goes without saying that a dichroic mirror or a dichroic prism can be used instead of B.

By configuring the optical engine as shown in FIG. 9, an image display device as shown in FIG. 14 is obtained. FIG. 14 is a schematic perspective view showing one embodiment of the video display device according to the present invention. In the figure, the optical system is shown in perspective. In the figure, 171 is an illumination optical system,
172 is an optical engine as shown in FIG. The optical axis of the light that has entered the light separation / combination unit 172 from the illumination optical system 171 is bent at a substantially right angle, and is emitted from the light separation / combination unit 172. This light passes through a projection lens 118 and is reflected by a reflection mirror 174 provided on the back of the cabinet.
And is projected on the screen 175. In this case, the optical axis of the separation / combination unit 172 and the projection lens 118 may be shifted to change the angle of incidence on the reflection mirror 174 on the rear surface. As a result, the size of the mirror can be reduced, and the size of the set in the depth direction can be reduced.
In this case, the optical axes of the analyzing prism and the color combining prism may be shifted. Further, the optical axis of the projection lens 118 and the optical axis of the color combining prism may be shifted stepwise.

FIG. 15 is a perspective view showing another embodiment of the optical system. The drawing is different from FIG. 14 in that a mirror 176 for converting the optical axis is provided. In this embodiment, by providing the mirror 176, an image can be directly projected on the screen.

Referring to FIG. 8, in the optical engine shown in FIG. 8, the optical axis of the light incident thereon, that is, the optical axis incident on the color separation mirror 102, and the light emitted from the polarizing beam splitter 105RGB to the projection lens. The optical axes are configured to be substantially parallel. In the figure,
It is obvious to those skilled in the art that the polarizing beam splitter can be replaced with a dichroic mirror or a dichroic prism.

In the embodiment shown in FIGS. 14 and 15, the optical system can be arranged compactly.

An image display device using the optical engine shown in FIG. 8 will be described with reference to FIG. FIG. 16 is a schematic perspective view showing another embodiment of the video display device according to the present invention. In the figure, the incident axis of light incident on the optical engine 178 from the illumination optical system 171 is substantially parallel to the optical axis emitted from the optical engine 178, and the light emitted from the optical engine 179 is reflected by the reflection mirror 179. The light is reflected to enter the projection lens 118, reflected by the reflection mirror 174 provided on the back of the cabinet 173, and projected on the screen 175. In this embodiment, since the back focus of the projection lens can be shortened,
The number of projection lenses can be reduced and the size can be reduced.

FIG. 17 is a perspective view showing still another embodiment of the optical system. In the figure, the arrangement example does not use the reflection mirror 179. Compared with the embodiment of FIG. 16, the image display device is slightly longer in the vertical direction, but can be shorter in the horizontal direction.

In FIGS. 14 and 16, when the light emitted from the projection lens is projected on the screen 175 by the reflection mirror 174 provided on the back of the cabinet 173, a lens such as a Fresnel lens is provided integrally with the screen 175 to spread the light. When the light having the light is made substantially parallel, the size of the set can be reduced.

In FIG. 1, the liquid crystal display elements 2R, 2G,
If the condenser lens 30 disposed in front of the projection lens 2B is considered to be integrated with the projection lens 20 and the first combined focal position exists near the stop surface of the projection lens 20, the polarization beam splitters 16G and 16RB, the color combining mirror Since the luminous flux passing through 19 can be reduced, these can be reduced in size. In particular, when a color combining polarization beam splitter or a dichroic prism is used instead of the color combining mirror 19, the effect of reducing the weight of the prism and reducing the cost can be obtained.

In FIG. 8 or FIG.
02, a dichroic prism or a dichroic mirror is used, and a polarizing beam splitter 105 RGB is used.
In the case of using a dichroic prism or dichroic mirror instead of, by setting the half value wavelength of the color separation dichroic prism or dichroic mirror and the half value wavelength of the color combining dichroic prism or dichroic mirror to different values, unnecessary light is eliminated, Color purity can be improved. For example, the dichroic characteristic of the incident light, that is,
When the wavelength is 00 nm, the high band half value wavelength is 590 nm, and the low band half value wavelength of the dichroic characteristics of the exit prism is 510 nm and the high band half value wavelength is 580 nm, 500 nm to 510 nm.
Of cyan and yellow light between 580 nm and 590 nm. This combination is also possible with a combination of a specific wavelength band polarization conversion element and a dichroic,
Furthermore, a combination of a specific wavelength band polarization conversion element and a polarization beam splitter is also possible. The light to be cut may be near-violet light or near-infrared light, and there are ten combinations.

[0118]

According to the present invention, the size and weight can be reduced, the color purity can be freely controlled, the color unevenness and the like can be improved, and the performance can be improved at the same time. Further, since the color separation means is performed by a combination of the polarization beam splitter and the specific wavelength region polarization conversion element, the influence due to the angle dependency is small, and the design of the color performance is facilitated. Therefore, a compact, high-brightness, high-quality optical engine or projection-type image display device can be realized. Further, since the number of parts can be reduced, cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a first embodiment of a projection type liquid crystal display device according to the present invention.

FIG. 2 is a schematic plan view showing a second embodiment of the projection type liquid crystal display device according to the present invention.

FIG. 3 is a schematic plan view showing a third embodiment of the projection type liquid crystal display device according to the present invention.

FIG. 4 is a schematic plan view showing a fourth embodiment of the projection type liquid crystal display device according to the present invention.

FIG. 5 is a schematic plan view showing a fifth embodiment of the projection type liquid crystal display device according to the present invention.

FIG. 6 is a schematic plan view showing a sixth embodiment of the projection type liquid crystal display device according to the present invention.

FIG. 7 is a schematic plan view showing a seventh embodiment of the projection type liquid crystal display device according to the present invention.

FIG. 8 is a schematic plan view showing an eighth embodiment of the projection type liquid crystal display device according to the present invention.

FIG. 9 is a schematic plan view showing a ninth embodiment of a projection type liquid crystal display device according to the present invention.

FIG. 10 is a characteristic diagram showing light transmittance.

FIG. 11 is a partial cross-sectional plan view showing an embodiment of how to attach a liquid crystal display element to a polarizing beam splitter.

FIG. 12 is a perspective view showing an embodiment of a polarizing beam splitter and an assembly thereof.

FIG. 13 is a side view for explaining attachment of a λλ wavelength plate.

FIG. 14 is a schematic perspective view showing an embodiment of a video display device according to the present invention.

FIG. 15 is a perspective view showing another embodiment of the optical system.

FIG. 16 is a schematic perspective view showing another embodiment of the video display device according to the present invention.

FIG. 17 is a perspective view showing still another embodiment of the optical system.

[Explanation of symbols]

1: light source, 2G, 2R, 2B, 107R, 107G, 1
07B: reflective liquid crystal display element, 5: reflector, 6: first array lens, 7: second array lens, 8: polarizing beam splitter (PBS), 10: condenser lens,
11: reflection mirror, 13: dichroic mirror, 14
... Incident polarizing plate, 16 ... G polarizing beam splitter, R-
B polarizing beam splitter, 17, 112a, 112b
... Specific wavelength selection polarization conversion element, 20 ... Projection lens, 22
.., Optical member, 23, prism glass material, 25, dielectric multilayer film, 101, polarization conversion element, 102, color separation mirror, 1
05G, 105RB, 105RGB ... polarizing beam splitter.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tomohiro Miyoshi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Digital Media Development Division, Hitachi, Ltd. 292 F-term in Hitachi Digital Media System Division (Reference) 2H099 BA09 BA17 CA01 CA11 DA00 5C058 AA06 EA12 EA13 EA14 EA26 5C060 DA04 DA05 GB05 GB10 HC09 HC14 HC19

Claims (41)

[Claims] 1. A reflective video display element for forming an optical image according to a video signal from light emitted from a light source unit, an illumination optical system for irradiating the reflective video display element with light, and the reflective video display element An optical engine for an image display device, comprising: projection means for projecting outgoing light from a light source, comprising: two polarization separation / combination elements for converting a polarization direction of light on an optical axis of the reflection-type image display element; An optical engine provided with a combination configuration of two color separation / combination means for reflecting or transmitting the light, or a combination configuration of three polarization separation / combination elements and one color separation / combination means. 2. The optical engine according to claim 1, wherein said color separation / combination means is disposed on an optical path after said polarization separation / combination element and immediately before a projection lens. 3. The optical engine according to claim 1, wherein two polarization separation / combination elements are provided at positions immediately before light entrance / exit for each of three RGB of said reflection type image display elements. , The 2
One polarization separation / combination element or one color separation means is combined almost immediately before the light is incident on the two polarization separation / combination elements, and one color combination means is provided at the outgoing light passage part of the reflection type image display element. An optical engine comprising: 4. The optical engine according to claim 1, 2 or 3, wherein said two polarization separation / combination elements and said two color separation / combination means are provided on an input / output optical axis of said reflection type image display element. Or a combination of the three polarization separation / combination elements and the one color separation / combination means, and a specific wavelength band polarization conversion element for converting the polarization of light in a specific wavelength band into a polarization direction at a predetermined angle. An optical engine characterized by being provided. 5. An image display element on which an optical image corresponding to an image signal is formed from light emitted from a light source unit, an illumination optical system for irradiating the image display element with light, and light emitted from the image display element. An optical engine having projection means for projecting on a screen, a polarization separation / combination element for polarizing light incident on the image display element, and detecting reflected light whose polarization has been converted by the image display element, Outgoing light of the light source unit, green, red,
A color separation unit that separates into blue, a specific wavelength band polarization conversion element that is arranged in front of the polarization separation / combination element in the optical path of the separated red and blue light and converts the polarization direction of light only in a specific wavelength band. An optical engine comprising: 6. The optical engine according to claim 5, wherein the specific wavelength band polarization conversion element is a wavelength plate that performs polarization conversion on light in a wavelength band near 400 to 500 nm or in a wavelength band near 600 to 700 nm. An optical engine, characterized in that: 7. The optical engine according to claim 5, wherein the specific wavelength band polarization conversion element makes the polarization directions orthogonal to each other with respect to a wavelength band near 400 to 500 nm and a wavelength band near 600 to 700 nm. An optical engine having characteristics. 8. The optical engine according to claim 5, wherein the specific wavelength band polarization conversion element has a boundary wavelength at which a polarization characteristic changes in a wavelength band for converting polarization and a wavelength band for not converting polarization. The optical engine is set to a value in the vicinity of 500 to 600 nm. 9. The optical engine according to claim 5, wherein the polarized light separating / combining element in the light path of the separated green light is:
An optical engine, comprising: a polarization splitting / combining element dedicated to a green light path, which is coated with a film so as to have a peak band in which transmittance or reflectance for green light is stable. 10. The optical engine according to claim 5, 6, 7 or 8, wherein the polarized light separating element in the optical path of the separated red and blue light has a transmittance for at least one of red and blue light. Alternatively, the optical engine is a dedicated polarization separation / combination element provided with a film so that the reflectance has a stable peak band. 11. The optical engine according to claim 5,6,7,8,9 or 10, wherein at least one of the green light path and the red and blue light paths after separating the green light. An optical engine, wherein a polarization rectifying element is provided before or after a polarization separation / combination element, and the polarization rectifying element is arranged before a specific wavelength band polarization conversion element that converts only a specific wavelength band. . 12. The optical engine according to claim 10, wherein said polarization rectifying element includes an optical component having color adjusting means. 13. An optical engine according to claim 5,6,7,8,9 or 10, wherein the polarized light of only the specific wavelength band is provided on the exit side of the polarization separation / combination element in the optical path of red and blue light. A specific wavelength band polarization conversion element for converting the direction, and a color synthesizing unit that synthesizes green, red, and blue light and makes the light incident on the projection unit, and the specific wavelength band polarization conversion element is one of red light and blue light. One of the polarization directions is rotated by about 90 degrees, and S-polarized light is converted to P-polarized light, and P-polarized light is converted to S-polarized light. Red and blue light are reflected by the color combining means and incident on the projection lens. When the red and blue light is converted into the S-polarized light, the red and blue light is transmitted through the color synthesizing means and is incident on the projection lens. An optical engine that converts light into light. 14. The optical engine according to claim 13, wherein the polarization direction of the green light incident on the color combining means is orthogonal to the polarization directions of the red and blue lights. 15. The optical engine according to claim 1, wherein at least one of the color separation / combination means is a dichroic prism, and is perpendicular to the optical axis in the color separation / combination direction. An optical engine having a configuration in which a chamfered portion is provided on one corner side larger than another corner side, and a structural member or another optical member is arranged on the chamfered portion. 16. The optical engine according to claim 1, wherein said color separation / combination means has a dielectric multilayer film. 17. A separating means for separating a first light, a second light and a third light, a first prism for guiding the first light to a first image display element, a second prism and a second prism. The third light is applied to the second and third light
A second prism for guiding the first light to the image display element, and a combining means for combining the first to third lights, and one or both surfaces of the first prism through which the first light enters and exits. An optical engine comprising: a first color adjustment film; and a second color adjustment film on one or both of the surfaces on which the second and third lights enter and exit. 18. The optical engine according to claim 17, wherein said combining means is a third prism, and said first prism surface through which said first light enters and exits and said first light enters said first prism surface. The first color adjustment film is provided on one or both surfaces of the third prism surface, and the second prism surface and the second prism surface through which the second light and the third light enter and exit. An optical engine, wherein the second color adjustment film is provided on one or both surfaces of the third prism surface on which light and the third light are incident. 19. The optical engine according to claim 17, wherein a specific wavelength band polarization conversion element is provided on at least one of the optical path of the first light and the optical path of the second light, and the color adjustment film and the specific An optical engine, wherein the color is adjusted by a wavelength conversion element. 20. A separating means for separating the first light, the second light and the third light, a first polarizing beam splitter for entering the first light into an image display element and analyzing the first light, A second polarizing beam splitter which enters the second and third image display elements and analyzes the light, respectively; a combining means for combining the first to third lights; A specific wavelength band polarization conversion element provided in an optical path of the first light and at least one of the second and third optical paths, and color adjustment is performed by the separation unit and the specific wavelength band polarization conversion element. An optical engine, characterized in that: 21. The optical engine according to claim 20, wherein first and second specific wavelength band polarization conversion elements are provided on the input and output surfaces of the second polarization beam splitter, respectively, and the separating means and the first and second specific wavelength band polarization conversion elements are provided. And an optical engine that performs color adjustment with the second specific wavelength band polarization conversion element. 22. The optical engine according to claim 21, wherein a half value of said separation means and a half value of said first and second specific wavelength band polarization conversion elements are combined to cut off light near 500 nm. And optical engine. 23. A color separating means, and a first prism which makes the first light separated by the color separating means incident on a first image display element and emits light from the first image display element. And the first and second lights separated by the color separation means into second and third lights.
A second prism that is incident on the first image display element and emits light from the second and third image display elements; a color combining unit that combines the first to third lights; And a polarizing plate disposed near at least one of the second prisms, wherein the polarizing plate is attached to a nearby prism. 24. The optical engine according to claim 23, wherein said color synthesizing means comprises a prism, and a polarizing plate disposed near said prism is attached to said prism. 25. An optical engine which modulates the light separated by the color separation means by an image display element, synthesizes the light by a color synthesis means and emits the light by an emission means, wherein the color separation means is one of a dichroic mirror and a dichroic prism. And the color synthesizing means is constituted by one of a dichroic mirror and a dichroic prism, and the half-value wavelength of the color separating means and the half-value wavelength of the color synthesizing means are set to different values to improve color purity. An optical engine characterized by the following. 26. A separating means for separating first light, second and third light, a first prism for guiding the first light to a first image display element, The third light is applied to the second and third light
A dichroic element comprising a dichroic mirror or a dichroic prism for the color separating means or the color synthesizing means. An optical engine for use, wherein a dichroic coat is provided on the dichroic element, and a thickness of the dichroic coat is changed according to an incident angle of light. 27. A separating means for separating first light, second and third light, a first prism for guiding the first light to a first image display element, The third light is applied to the second and third light
A second prism that guides the image display device, and a combining unit that combines the first to third lights. The color separating unit or the color combining unit includes a prism including a polarizing beam splitter or a dichroic prism. An optical engine for use, wherein a glass material is changed according to the use of the prism. 28. An optical engine comprising a color separating means, a polarizing beam splitter for light analysis, and a color synthesizing means, wherein one of the color separating means and the color synthesizing means uses a prism comprising a polarizing beam splitter or a dichroic prism. 3. The optical engine according to claim 1, wherein the polarization beam splitter for analysis and the glass material of the prism are changed depending on the application, and the volume of the prism is made smaller than the volume of the polarization beam splitter for analysis. 29. A separating means for separating first light, second and third light, a first prism for guiding the first light to a first image display element, The third light is applied to the second and third light
And a liquid crystal display element having a frame for filling the liquid crystal and a cover glass of the liquid crystal. An optical engine, wherein the liquid crystal display element is directly bonded to the first and second prisms, which are composed of a beam splitter and a dichroic prism. 30. A separating means for separating first light, second and third light, a first prism for guiding the first light to a first image display element, The third light is applied to the second and third light
And a liquid crystal display element having a frame for filling the liquid crystal and a cover glass of the liquid crystal. An optical engine, wherein an adjusting plate is bonded to the first or second prism including a beam splitter or a dichroic prism, and the liquid crystal display element is bonded to the adjusting plate. 31. In an optical engine having a prism formed by bonding a first prism piece and a second prism piece, the length of the first prism piece is made equal to the length of the second prism piece. And a plurality of prisms each having the first prism piece and the second prism piece bonded together such that a step is provided between the first prism piece and the second prism piece. An optical engine for positioning the plurality of prisms using the stepped portion. 32. The optical engine according to claim 31, further comprising: an assembling bracket having a plurality of pedestals on which the first prism piece is mounted and a plurality of second pedestals on which the second prism piece is mounted. An optical engine, wherein the plurality of prisms are attached to the metal fitting. 33. An optical engine according to claim 31, wherein a prism provided on an optical path through which light enters the liquid crystal display element has a light incident side as a second prism piece and a light emission side as a first prism piece. The prisms are arranged so as to be prism pieces, and the prisms provided on the optical path where light is emitted from the liquid crystal display element are arranged so that the light incident side is the first prism piece and the light emission side is the second prism piece. An optical engine. 34. A prism formed by bonding a first prism piece and a second prism piece, a liquid crystal display element disposed near the prism, and a liquid crystal display element between the prism and the liquid crystal display element. An optical engine having a wave plate disposed therein, wherein a length of said first prism piece is shorter than a length of said second prism piece, and said first prism piece and said second prism The first prism piece and the second prism piece are attached to each other so as to provide a step between the pieces to form a prism having a step, and a surface of the first prism that is in contact with the step is referenced. An optical engine for adjusting the wavelength plate. 35. An optical engine in which light separated by a color separation means is modulated by an image display element, synthesized by a color synthesis means, and emitted by an emission means, wherein green light incident on the color synthesis means is S-polarized light. Light, red light and blue light are P-polarized light,
An optical engine, wherein an emission optical axis of an image display device for modulating green light and an emission optical axis of the color synthesizing means are substantially perpendicular to each other. 36. An optical engine in which the light separated by the color separation means is modulated by the image display element, synthesized by the color synthesis means, and emitted by the emission means, wherein green light incident on the color synthesis means is The optics are P-polarized light, red light and blue light are S-polarized light, and the emission optical axis of an image display device for modulating green light and the emission optical axis of the color combining means are substantially parallel. engine. 37. An optical engine for modulating the light separated by the color separation means with an image display element, synthesizing the light by a color synthesis means, and outputting the light by an emission means, wherein the color separation / synthesis means and And first and second image display elements arranged substantially orthogonal to each other, and separates light incident on the color separation / combination means into first light and second light to separate the light into first light and second light, respectively. 1 and the light emitted from the color separation / combination means that is incident on the second image display element and combines the first and second lights obtained from the first and second image display elements. The axis is substantially orthogonal to the optical axis of the light incident on the color separation / combination means, and the emission optical axis of the color separation / combination means is configured to be substantially parallel to the optical axis of the emission means. Optical engine. 38. An optical engine which modulates the light separated by the color separating means by the image display element, combines the light by the color synthesizing means and emits the light by the emitting means, comprising: an optical axis converting means; The image display unit and the color combining unit constitute a color separation / combination unit, and an optical axis of light incident on the color separation / combination unit is substantially parallel to an optical axis of light emitted from the color separation unit. Wherein the optical axis of the light emitted from the color separation / combination unit is converted by the optical axis conversion means and the light is incident on the projection means. 39. An optical engine according to claim 37, further comprising a screen provided with a lens for making light substantially parallel, and an optical axis converting means for changing an optical axis of light emitted from said projecting means. A projection type image display device, wherein an optical axis of light emitted from the projection means is converted and projected on the screen. 40. An optical engine for modulating the light separated by the color separation means with an image display element, synthesizing the light with a color synthesizing means and emitting the light with an emission means, wherein a condenser lens is provided in front of the image display element. An optical engine, wherein a first focal point of the condenser lens or a lens group subsequent to the condenser lens is located near a stop surface of the projection means. 41. An image display device comprising the optical engine according to any one of claims 1 to 38 and 40.