JPH11249073A - Polarized light illuminating device and projection display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a device size and to use the projection lens of a large F number concerning the polarized light illuminating device of high efficiency and high uniformity. SOLUTION: Light flux emitted from a light source part 2 is converged by adopting a single elliptical surface reflecting mirror 101 having a second focal distance less than 200 mm for the light source part 2, at the same time, a concave lens 6 for making the light flux radiated from the light source part 2 into almost parallel light beams is arranged between the light source part 2 and a first lens plate 3 or between the first lens plate 3 and a second lens plate 4, and the angle of light flux is converted to almost parallel light within 5 deg.. The first lens plate 3 is composed of plural rectangular lens arrays, and the light flux is uniformly illuminated through a condenser lens array 201, which consists of the second lens plate 4, to an illuminating area 5. Since the size of the second lens plate is smaller than the opening part of the light source part, concerning this polarized light illuminating device, the size of optical color separating parts and optical color synthesizing parts can be reduced and the F number of the projection lens can be enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarized light illuminating device and a projection type liquid crystal display device using the same, and more particularly to a polarized light illuminating device for uniformly illuminating a rectangular illumination area or the like using polarized light having a uniform polarization direction. The present invention relates to a projection type liquid crystal display device in which polarized light emitted from the polarized light illuminating device is modulated by a light valve and an image is enlarged and displayed on a screen.

[0002]

2. Description of the Related Art In a light valve such as a liquid crystal, image information is modulated by rotating a polarization direction of an incident light beam. For this reason, it is necessary to make the polarization direction of the light beam incident on the light valve uniform. However, since a light source used in a liquid crystal projection type device or the like emits light having a random polarization direction, only half of a light beam emitted from the light source can be used as it is. As a method of increasing the utilization efficiency, a polarization conversion system that separates a light beam into S-polarized light and P-polarized light, and rotates one or both polarized lights to make polarized lights in the same direction has been put to practical use.

[0003] Further, since the light flux emitted from the light source has a light intensity distribution, the light valve also has an illuminance distribution when the light valve is irradiated through an elliptical reflecting mirror or a parabolic reflecting mirror. In order to make the illuminance distribution uniform, an integrator technique has been put to practical use in which an irradiation area (primary irradiation area) by a light source is divided into minute sections and each minute section irradiates a light valve (secondary irradiation area). .

[0004] Conventionally, this type of polarized light illuminating apparatus has been disclosed in, for example, Japanese Patent Application Laid-Open No. 8-304739.
It has already been put to practical use as an optical system having two functions. FIG. 6 is a schematic diagram of a polarized light illuminating device disclosed in the publication. The polarized light illuminating device includes a light source unit 2 that emits light having a random polarization direction and a plurality of rectangular condenser lenses. A first lens plate 3 for forming a light source image;
A second lens which is placed near a position where a plurality of secondary light source images are formed and includes a condenser lens array 201, a polarization separation prism array 202, a λ / 2 phase plate 203, and an emission side lens 204 A configuration having the plate 4 is adopted.

Further, in the second lens plate 4, the condenser lens array 201 is composed of a plurality of condenser lenses, and the polarization separation prism array 202 converts the randomly polarized light into two P-polarized lights and two S-polarized lights. It separates into linearly polarized light, and is constituted by a plurality of polarization beam splitters or a combination of a plurality of polarization beam splitters and a plurality of reflection mirrors. The λ / 2 retardation plate 203 is disposed on the exit surface side of the polarization separation prism array 102, and the exit lens 204 adopts a configuration disposed on the exit surface side of the λ / 2 retardation plate 203. The light source section 2 has a parabolic reflector 102.

Next, the operation of the lighting device having the above-described configuration will be described. Light having randomly polarized light emitted from the light source unit 2 has a light intensity distribution. This is divided into a plurality of rectangular minute area lights by a plurality of rectangular condenser lenses constituting the first lens plate 3. At this time, the minute area light is, as the name implies, light in a minute area, so that the light intensity distribution is relatively uniform. Each of these minute area lights irradiates the vicinity of the illumination area 5 via the condenser lens array 201 constituting the second lens plate 4. At this time, the emission side lens 204 constituting the second lens plate 4
All of the plurality of minute area lights illuminate the illumination area 5. Thereby, the illumination area 5 is irradiated with a uniform light distribution.

The plurality of rectangular condensing lens arrays 201 forming the first lens plate 3 form a plurality of secondary light source images near the condensing lens array 201 forming the second lens plate 4. . Utilizing the gap between the secondary light source images, the secondary light source image is separated into S-polarized light and P-polarized light by a polarization splitting prism array 202 (parallel type) similarly constituting the second lens plate 4. One or both of the separated polarized lights are combined with the polarization plane rotated by the λ / 2 retardation plate 203 so that the polarization planes are aligned. by this,
The illumination area 5 is illuminated with a high efficiency of light utilization.

Here, since the light source 2 is constituted by the parabolic reflector 102, the first lens plate 3 and the second lens
The light incident on the lens plate 4 is substantially parallel light, and the substantially parallel light similarly enters the polarization splitting prism array 202. ± 3 to 5 for systems currently in practical use
It is designed such that a light beam having a maximum incident angle of about degree is incident.

[0009]

The first problem is that the F-number of the projection lens becomes small. The reason for this is that the light incident on the first lens plate 3 must be set at substantially parallel angles of ± 5 degrees or less. For this reason, when the light source unit 2 is a parabolic reflector 101 as shown in the figure, the size of the first lens plate 3 is almost the same as the size of the opening of the reflector of the light source unit 2, and at the same time, the first lens plate 3 and the second lens plate 4 must be the same size, so that the F number of the illumination system is determined by the distance and size between the emission side lens 204 and the illumination area 5.

As a result, it is necessary to reduce the F number of the projection lens, resulting in an increase in the cost of the projection lens. In addition, the size of the mirror of the color separation / combination system increases, and the size of the apparatus increases. When the light source unit 2 is an ellipsoidal reflecting mirror, the second focal length is 500 mm or more when the opening of the reflecting mirror is about 70φ, and the second focal length even when it is a small reflecting mirror whose opening is about 20φ. Must be a long elliptical reflecting mirror of 200 mm or more. For this reason, there is no advantage of using an ellipsoidal reflecting mirror, and it is necessary to reduce the F number of the projection lens as in the case of the parabolic mirror, and the cost of the projection lens is increased. Further, the mirror size of the color separation / combination system is increased, and the size of the apparatus is increased.

An object of the present invention is to provide a highly efficient and uniform polarized light illuminating device using a light source section having a single ellipsoidal reflecting mirror and a projection lens having a large F number, and a projection display device using the same. It is.

[0012]

According to the present invention, a light source unit for emitting light having a random polarization direction and a plurality of rectangular condenser lenses having a rectangular outer shape are emitted from the light source unit. A first lens plate for condensing light to form a plurality of secondary light source images, and a light arranged in the vicinity of a position where the plurality of secondary light source images are formed and having a random polarization direction. And a second lens plate that separates the two into two linearly polarized light beams and combines the polarized light beams in the same polarization direction, wherein the second lens plate is disposed between the opening of the reflecting mirror and the first lens plate or the second lens plate. A polarized light illuminating device including a concave lens provided between the first lens plate and the second lens plate is obtained.

The second lens plate includes a condensing lens array in which a plurality of rectangular condensing lenses corresponding to the respective secondary light source images are arranged, a polarization separating prism array,
A half-wave retardation plate and an output lens are arranged in this order from the light incident side, and the second lens plate corresponds to each of the secondary light source images. A condenser lens array in which a plurality of rectangular condenser lenses are arranged; a reflector having a plurality of slits arranged to correspond to the condenser lenses of the condenser lens array; and reflection between the slits in the reflector. Cover at least 1 /
It is characterized in that a four-wavelength phase difference plate, a plate-shaped polarization separator, and an emission lens are arranged in this order from the light incident side.

Further, the light source unit is a single ellipsoidal reflecting mirror, and the second focal length of the single elliptical reflecting mirror is 200 mm or less.

The operation of the present invention will be described. By using a single elliptical reflector for the light source, a first lens plate having a size equal to or smaller than the opening of the reflector and a second lens plate smaller than the opening of the reflector are used. Can be. However, simply employing a single-ellipsoidal reflecting mirror having a second focal position of 200 mm or less results in an angle of light incident on the first lens plate and the second lens plate of 5 degrees or more. I will. This angle causes an angle dependence of the transmittance of the polarizing prism array constituting the second lens plate, resulting in a decrease in brightness and the occurrence of color unevenness.

Here, between the light source unit and the first lens plate,
Alternatively, by providing a concave lens between the first lens plate and the second lens plate for converting a light beam radiated from the reflecting mirror into a substantially parallel light beam, a polarization splitting prism finally forming the second lens plate The luminous flux incident on the array can be reduced to 5 degrees or less, so that a decrease in brightness and the occurrence of color unevenness can be suppressed. In addition, the second smaller than the diameter of the reflecting mirror of the light source unit.
Can be used, the F-number of the projection lens can be increased, and the color separation and color combining optical components can be reduced.

[0017]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, and portions equivalent to those in FIG. 6 are denoted by the same reference numerals. Referring to FIG. 1, the light source unit 2 is a single ellipsoidal reflecting mirror 10.
1, between the light source unit 2 and the first lens plate 3,
A concave lens 6 for converting a light beam emitted from the light source unit into a substantially parallel light beam is provided. The light source unit 2 includes a single elliptical reflecting mirror 101 having a second focal length of 200 mm or less, and the light emitted from the light source unit 2 is directly converged on the concave lens 6. Thereby, the opening of the concave lens 6 can be made smaller than the opening of the reflecting mirror of the light source unit 2.

The light beam incident on the concave lens 6 is converted into parallel light by the concave lens 6 and is incident on the first lens plate 3. The light incident on the first lens plate 3 forms a secondary light source image near the second lens plate 4 by a plurality of rectangular condensing lenses constituting the first lens plate 3. Then, the image of each of the rectangular condenser lenses of the first lens plate 3 is transferred to the irradiation area 5 via the condenser lens array 201 constituting the second lens plate 4.

At this time, the polarization separating prism array 202 and the λ / 2 retardation plate 20 constituting the second lens plate 4
3 aligns the randomly polarized light into polarized light in the same direction, and outputs the first lens plate 3
Can be transferred to the illumination area 5 on all of the incident light images on all the condensing lens arrays 201.

At this time, the size of the first lens plate 3 and the second lens plate 4 becomes almost the same as the size of the opening of the concave lens 6 which is smaller than the opening of the reflecting mirror of the light source unit 2, thereby projecting. The F number of the lens can be increased, and the color separation / synthesis optical components can be reduced.

FIG. 2 is a view showing another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals. FIG.
1 is different from the example of FIG. 1 only in that the concave lens 6 is disposed between the first lens plate 3 and the second lens plate 4. Same as 1. Also in this example, the size of the second lens plate 4 becomes small, the F number of the projection lens can be increased, and the size of the color separation / synthesis system optical component can be reduced.

FIG. 3 is a view showing another embodiment of the present invention, and the same parts as those in FIGS.
Referring to FIG. 3, the configuration of the second lens plate 4 is shown in FIGS.
The configuration of the second lens plate is different from that of Japanese Patent Application No. 9-22945 filed by the present applicant.
No. 1 (filed on August 26, 1997). The details of the second lens plate 4 in FIG. 3 are shown in FIG. 4, and the condenser lens array 201, the strip aluminum mirror (slit-shaped reflection plate) 205, and the λ / 4 phase difference plate (1/4 wavelength A plate 207, a polarization splitting prism array 206 as a polarization splitter, and an emission side lens 204 (omitted in FIG. 4) are arranged in this order from the light incident direction.

The width P of the basic structural unit of the polarization separator 206
1 is each condenser lens 1 of the second condenser lens array 201
04 is equal to the width S1. The slit of the slit-shaped reflection plate 205 is an opening, and the second condenser lens array 20
1 are regularly arranged so as to correspond to the condensing lenses 104 in the column. Quarter-wavelength plates 207 are respectively arranged on the emission surface side of the plate portion between the slits in the reflection plate 205.

Each basic constituent unit of the polarization separator 206 is arranged so as to correspond to a pair of a reflection part and a slit part adjacent to the slit-like reflection plate 205. Also,
Width X about half of the width of the basic constituent unit of the polarization separator 206
p155, the width X154 of each quarter-wave plate 207,
Each slit width X153 of the slit reflection plate 205 is equal. Incidentally, reference numeral 152 denotes a system main optical axis.

FIG. 5 schematically shows, in an enlarged manner, the state of light when passing through each component of the configuration of FIG. The random light of the polarization direction incident on the second condenser lens array plate 201 passes through the slit portion of the reflection plate 205 and the gap between the quarter-wave plates 207, and then is polarized by the polarization separator 206. Are separated into two types of linearly polarized light, namely, P-polarized light and S-polarized light. That is, the P-polarized light passes through the polarization separator 206 without changing the traveling direction. On the other hand, the S-polarized light is reflected by the polarization splitting film 105 of the polarization splitter 206 and thereafter reflected by the polarization splitting film 106 (however, at this time, the optical axis 52 shifts by about Xp), and
The light enters the wave plate 207.

Here, the S-polarized light is applied to the 波長 wavelength plate 20.
7, the light is converted into elliptically polarized light by the rotation of the polarization plane,
The light is reflected by the slit-like reflecting plate 205. The reflected elliptically polarized light enters the quarter-wave plate 207 again, and is converted from elliptically polarized light to P-polarized light by the rotation of the polarization plane.
The light passes through the polarization splitter 206 as it is. Finally, in these two optical paths, the P-polarized light exits the polarization separator 206 at substantially parallel angles.

In this way, the light beam aligned with the P-polarized light is guided to the illumination area 5 by the exit lens 204, and forms an image on the illumination area 5 in an overlapping manner. The random light in the polarization direction from the light source unit 2 is converted into one linearly polarized light, and almost all the light reaches the illumination area 5. For this,
In the illumination area 5, the light is uniformly illuminated with almost one polarized light, there is almost no light loss, and the light utilization is extremely high.

Also in this embodiment, a concave lens 6 may be provided between the first condenser lens plate 3 and the second lens plate 4 as in FIG.

It can be easily inferred that the polarized light illuminating device of each of the above structures can be used for a projection type liquid crystal display device, and details thereof will be omitted. Japanese Patent Application No. 9-229451).

[0031]

The first effect is that a small and low-cost projection display device can be provided. The reason is that the F-number of the illumination system can be increased by combining a single ellipsoidal reflecting mirror with a highly efficient and highly uniform polarizing illumination device, and therefore a low-cost, large-number F-number projection lens is used. This is because the size of the device can be reduced because the color separation / synthesis optical components can be reduced at the same time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 4 is a configuration diagram showing details of a second lens plate in FIG. 3;

FIG. 5 is a schematic enlarged view of a part of FIG. 4;

FIG. 6 is a diagram showing an example of a conventional polarized light illumination device.

[Explanation of symbols]

 Reference Signs List 2 light source unit 3 first lens plate 4 second lens plate 5 illumination area 6 concave lens 101 single elliptical reflecting mirror 201 condensing lens array 202, 206 polarization separation prism array 203 λ / 2 phase difference plate 204 emission side lens 205 Strip reflection mirror 207 λ / 4 phase difference plate

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI G02F 1/1335 530 G02F 1/1335 530

Claims (6)

[Claims] 1. A light source unit that emits light having a random polarization direction, and a plurality of rectangular condenser lenses having a rectangular outer shape. A first lens plate for forming a light source image, and a first lens plate disposed near a position where a plurality of secondary light source images are formed, for separating the light having a random polarization direction into two linearly polarized lights, and A polarized light illuminating device comprising: a second lens plate for synthesizing the light in the same direction;
And a concave lens provided between the first lens plate and the second lens plate. 2. The second lens plate comprises: a condenser lens array in which a plurality of rectangular condenser lenses corresponding to each of the secondary light source images are arranged; a polarization separation prism array;
2. The polarized light illuminating device according to claim 1, wherein the wavelength phase difference plate and the output lens are arranged in this order from the light incident side. 3. The condenser lens array in which a plurality of rectangular condenser lenses corresponding to each of the secondary light source images are arranged, and the second lens plate corresponds to a condenser lens of the condenser lens array. A reflector having a plurality of slits arranged in such a manner as to form a quarter-wave retardation plate that covers at least a reflecting portion between the slits in the reflector, a plate-shaped polarization separator, and an output lens are arranged in this order. The polarized light illuminating device according to claim 1, wherein the polarized light illuminating device is arranged from a light incident side. 4. The polarization illuminating device according to claim 1, wherein the light source unit is a single ellipsoidal reflecting mirror. 5. The single-ellipsoidal reflecting mirror has a second focal length of 2
The polarized light illuminating device according to claim 4, wherein the distance is not more than 00 mm. 6. A projection display device using the polarized light illumination device according to claim 1 as a light source.