JP2002374004A - Led array panel and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED array panel where a plurality of LED elements are arranged, and illumination light having a uniform intensity distribution of light on an irradiation surface can be outputted. SOLUTION: Each LED element 3 for composing an LED array panel 1 is arranged around an optical axis 72 at angles having a difference of 90 degrees, a light having an intensity distribution with a fixed pattern being outputted from each LED element 3 is overlapped for averaging, and the intensity distribution of illumination light outputted from the LED array panel 1 becomes nearly uniform over the irradiation surface. By using the lighting device which uses the array panel 1, a compact projector that can display images which have small amount of irregularity or the like can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device and an LED array panel used for the lighting device.

[0002]

2. Description of the Related Art In a conventional projector, a bulb lamp is employed as a light source or an illuminating device. However, this bulb lamp is replaced with an LED array panel using an LED element which is excellent in miniaturization and power saving. It is being considered to replace it. In this array panel, a plurality of LED (light emitting diode) elements are arranged almost two-dimensionally on a plane or a curved surface to form a lighting device or a light source.

[0003]

FIG. 5 shows an example of an optical system of a projector using an LED panel. The projector 110 uses a lighting device 90 having an LED array panel 100 as a light source. The LED array panel 100 has a flat support panel and a plurality of individual (independent) panels arranged thereon in a matrix. L
An ED element 3 is provided. Then, the illumination light or the illumination luminous flux emitted from each LED element 3 of the LED array panel 100 along the optical axis 71 is condensed by the integrator 103 constituted by a set of fly-eye lenses 107 and the field lens 104. The lenses 106 are superposed via a lens 106 on an illumination surface, that is, a video display element (light valve) 105 such as a liquid crystal panel (LCD) so that the illumination intensity distribution becomes uniform. After the intensity is modulated so as to become video data, it is projected on a screen via a projection lens 108.

However, when an image is projected on a screen by a projector 110 using an LED array panel 100 as shown in FIG. 5, uneven illuminance unevenness, that is, shading, which is not accompanied by image data or a projection optical system, is seen on the screen. The present inventors have found that. LED
In the array panel 100, since the same type of LED elements 3 are arranged in a matrix, it can be considered that the same effect as the integrator appears in optical design. Therefore, as shown in FIG. 5, only by arranging the field lens 104 immediately before the LED array panel 100, theoretically, a uniform illuminance distribution can be obtained on the surface of the video display element at a predetermined position without using an integrator. As a result, the cost and size of the projector can be reduced.

There is a possibility that this problem can be solved by inserting an integrator composed of small lenses with a fine pitch, which has a high effect of making the illumination intensity distribution uniform. However, adoption of such an integrator leads to an increase in cost and size of the lighting device. As described above, a lighting device employing an LED array panel should originally be able to obtain a substantially uniform illuminance distribution without using an integrator.

Accordingly, in the present invention, as described above, the cause of the illuminance unevenness is clarified while the LED array panel is employed, and furthermore, even if the integrator is not used, the illuminance unevenness is generated on the screen. An object of the present invention is to provide an LED array panel capable of projecting no illuminating light or an image and a compact illuminating device using the same.

[0007]

It is considered that the illuminance non-uniformity generated on the screen is caused by the non-uniformity of the luminance of the illumination light beam illuminating the LCD panel surface. When the inventors of the present application examined the illumination pattern on the screen, it was found that an LCD, which is a means for modulating the radiated light flux having a regular pattern caused by the shape of the light emitting chip in each LED element as it is, is enlarged and superimposed as it is. It was found that the light was projected on a video display device such as a camera, and that it was reflected on the screen.

In the LED array panel, in order to regularly wire a plurality of LED elements constituting the array panel, the LED elements arranged in an array are angled or angled so that the current introduction terminals are oriented in the same direction. The orientation is aligned. For example, as schematically shown in FIG. 6, in the LED array panel 100 in which illuminance unevenness occurs, all L
The ED elements 3 are arranged so that the directions (rotational orientations) of the panel with respect to the optical axis 71 are all the same. For this reason, the electrode 3e on the upper surface of the light emitting chip inside the LED element 3,
The direction of the light emitting section 3d without electrodes is the same for all the LED elements 3, and their arrangement is regular and constant. Therefore, the design of the wiring pattern on the LED element 3 and the mounting work are facilitated.

However, while the mounting work and the like are facilitated, if a certain pattern is present in the intensity distribution of the light emitted from the LED elements mounted on the panel when the LED array panel is adopted, these patterns may be used. When a light beam from an LED element is condensed by a field lens on a unit that modulates the intensity on a pixel-by-pixel basis, a certain pattern of each LED element is superimposed while being aligned. For this reason, uneven illuminance occurs on the surface of the modulating means, and further, an image having uneven illuminance is projected on the screen. In particular, in blue and green high-brightness LED elements that have been put into practical use in recent years, the light emitting surface of the light emitting chip has a complicated layout, and accordingly, a certain pattern is generated in the intensity distribution of emitted light.

On the other hand, in the LED array panel of the present invention, by arranging the LED elements at different angles around the optical axis, an LE having a constant pattern of intensity distribution is obtained.
The light emitted from the D element is made uniform on the surface irradiated by the LED array panel. That is, the LED array panel of the present invention has a plurality of LED elements that emit light having a pattern of intensity distribution that is rotationally symmetric about the optical axis. They are arranged at an angle that differs by half the angle. That is, in the LED array panel studied above, in order to regularly wire the individual LED elements, the individual LED elements are all aligned so that the current introduction terminals face in the same direction. Was. On the other hand, in the present invention, instead of aligning all the directions around the optical axis of the LED elements constituting the LED array panel, the mounting angle around the optical axis of the LED elements is changed, so that the light emitted from each LED element is emitted. Certain patterns are being neglected. As a result, the luminous flux projected from the plurality of LED elements arranged on the LED array panel onto a predetermined surface has a non-uniform spatial intensity distribution of light due to a constant pattern of light of each LED element. Can be canceled, and the illumination intensity distribution in the plane irradiated by the illumination device of the present invention having the LED array panel can be made uniform.

That is, in the present invention, when the light emitted from the LED element has a certain pattern, attention is paid to the fact that the certain pattern is effectively a substantially rotationally symmetric pattern. By arbitrarily changing the rotation angle and arranging the rotation angle at half the rotation angle of the rotational symmetry, a fixed pattern emitted from each LED element is canceled out as a whole LED array panel.
For example, when the LED elements have two rotational symmetries, that is, a shape or configuration that overlaps when rotated by 180 degrees around the optical axis, the intensity distribution of light emitted from each LED element is centered on the optical axis. Becomes two times rotationally symmetric.
Therefore, by arranging the LED element so as to rotate by half of the rotationally symmetric rotation angle, that is, by 90 degrees, the LED element is rotated.
As the light for illuminating a predetermined surface from the array panel, uniform illumination light can be obtained by canceling out two rotationally symmetric fixed patterns.

Although the angles of a plurality of LED elements arranged on the array panel may be changed between adjacent LED elements, since the wiring pattern is not uniform, wiring design becomes troublesome and mounting is troublesome. Take it. On the other hand, a plurality of L
It is preferable that the ED elements are divided into a plurality of groups and arranged so that the LED elements belonging to the groups have the same angle around the optical axis. Since the mounting angles around the optical axis are the same between the LED elements arranged in a certain section divided into groups, wiring patterns can be aligned, and wiring design and mounting work can be facilitated. Therefore, the intensity distribution of the illumination light output as the LED array panel can be made uniform, and further,
An LED array panel that can be easily wired and mounted can be realized.

Therefore, an illuminating device including the LED array panel of the present invention and a lens system for irradiating the light emitted from the LED array panel to the means for modulating the intensity in pixel units (dot units) is employed. Thereby, it is possible to suppress the occurrence of uneven illuminance in an image projected on a screen or the like. Therefore, it is possible to provide an LED array panel capable of projecting illumination light or an image without unevenness in illuminance on a screen without using an integrator and a compact illumination device using the same. Then, in order to supply more uniform illumination light, L
It is also effective to provide a holographic diffuser for diffusing the light emitted from the ED array panel, for example, immediately before the modulating means for illuminating with the illumination device of the present invention.

Further, by employing the irradiation device of the present invention and providing a means for modulating light using the illumination device as a light source and a lens system for projecting the modulated light onto a screen, there is no illuminance unevenness. An image display device such as a projector that can display a bright, clear, high-quality image can be provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lighting device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a projector using the lighting device according to the present invention. The projector 30 according to the present embodiment includes a lighting device 10 arranged along an optical axis 71, a liquid crystal panel (video display element) 20 capable of intensity-modulating a light beam output from the lighting device 10 in pixel units, and And a lens system 28 for projecting the light beam modulated by 20. Then, the image formed on the liquid crystal panel 20 is enlarged and displayed on a screen or the like by the lens system 28.
The illumination device 10 of the present example includes a substantially square LED array panel 1 in which a plurality of LED elements 3 are arranged on a surface 11a of a panel 11, a field lens 4 arranged to cover the surface 11a, and a diffuser. It has a plate 18 and a condenser lens 19 arranged near the liquid crystal panel 20. As shown in FIG. 2, a plurality of LED elements 3 are formed on a surface 11a of a panel 11 serving as a substrate of the LED array panel 1 so as to form a two-dimensional matrix or array.
Is arranged.

FIG. 3 shows an LED array panel (LE) of this embodiment.
2 shows a part of the LED element 3 arranged on the (D light emitting panel) 1 in an enlarged manner. In the LED array panel 1 of this example, a plurality of LED elements 3 having the same configuration
Is arranged. In these LED elements 3, a light emitting chip 3c is disposed at the center, and a reflector cone 3b is disposed outside the light emitting chip 3c.
Are further molded in a cylindrical shape with a transparent resin, and the head portion has a lens shape.
The light emitting chip 3c has a substantially square shape when viewed from above, that is, from the light emission side, and has electrodes 3e (black portions in this figure) at two diagonal corners thereof. Also, 2
The shapes of the two electrodes need not always be the same. Therefore,
On the upper surface of the light emitting chip 3c, a portion excluding the electrode 3e becomes the light emitting unit 3d. For this reason, the LED element 3 of this example has a rotationally symmetrical shape twice around the optical axis 72 centered on the shape of the light emitting portion 3d, and the intensity distribution of the light emitted from the light emitting portion 3d ( Similarly, the intensity distribution of the cross section of the light beam) has a rotationally symmetrical pattern substantially twice about the optical axis 72, that is, a rotational angle of 180 degrees.

As shown in the enlarged view of FIG. 3, the LED array panel 1 of this embodiment is also arranged regularly so that the plurality of LED elements 3 emit light along the optical axis 71 shown in FIG. ing. However, in the individual LED elements 3, the LED elements 3 adjacent in the column or row direction are separated from each other by the optical axis 72.
, The rotation angle (180 degrees) of the pattern of the intensity distribution of the light emitted from each LED element 3
Are arranged so that the angle around the optical axis is different by 角度 of the angle. Therefore, the number of LED elements 3 in which the electrodes 3e are arranged diagonally to the right in the drawing and the number of LED elements 3 in which the electrodes 3e are arranged diagonally to the left so that the angle around the optical axis differs by 90 degrees are almost the same. The same number is arranged on the substrate 11. For this reason, the intensity distribution of the light emitted from each LED element 3 is equal to 2 with respect to the optical axis 72 as described above.
Although a rotationally symmetric pattern is shown, the same number of LED elements 3 are arranged on the panel 11 so that the angles around the optical axis are different by 90 degrees. The rotationally symmetric patterns are superimposed such that they are interpolated with each other. Therefore, from the LED array panel 1 of the present example, illumination light having a strong and more uniform spatial distribution (intensity distribution) in which light from the plurality of LED elements 3 is synthesized is applied to the liquid crystal panel 20.

As described above, the LED array panel 1 of this embodiment
Focusing on the fact that the intensity distribution of the light emitted from each LED element 3 has a constant rotationally symmetric pattern,
By regularly changing the angle around the optical axis when the D element 3 is arranged, a rotationally symmetric constant intensity pattern is canceled. Therefore, the above-described array panel 1
In the case of 00, the pattern of the intensity distribution of the light emitted from the LED element 3 is reflected on the pattern of the intensity distribution of the light emitted from the lighting device 90, and a pattern indicating a certain uneven illuminance is displayed. In the lighting device 10 of this example, LE
Each LED is used to positively use a constant rotationally symmetric intensity distribution pattern of light emitted from the D element 3 to eliminate the intensity distribution pattern of emitted light and to obtain uniform illumination light.
The element 3 is arranged. As a result, the projector 30 can obtain uniform illumination light with less luminance unevenness or illuminance unevenness. As LED elements exhibiting a constant pattern in which the intensity distribution of emitted light is strong, an LED element that emits blue light made of a gallium-nitrogen-based material and an LED element that emits green light are currently known. And 3 in total with existing red LED elements
The present invention is effective for a display device requiring primary color light, a white lighting device, and the like.

As described above, the illumination device 10 of the present embodiment outputs illumination light having a relatively uniform spatial distribution as a whole on the irradiation surface (in this example, the incident surface of the liquid crystal panel 20). 5, the integrator 107 using an expensive fly-eye lens is not required as in the lighting device 90 shown in FIG. Therefore, according to the present invention, it is possible to provide the illumination device 10 that outputs relatively uniform illumination light while being low-cost and compact. For this reason, by employing the illumination device 10 of the present example, it is possible to provide the projector 30 that can project a relatively high-quality image while being low-cost and compact.

Further, as shown in FIG. 1, between a lighting device 10 as a light source and a liquid crystal panel 20 as a light valve.
It is possible to irradiate the liquid crystal panel 20 with more uniform illumination light by inserting a light diffusing plate 18 that diffuses light in a radial direction of a plane perpendicular to the optical axis, for example, with appropriate characteristics using holography. It is possible. For this reason,
Even if an integrator using a fly-eye lens occupying an expensive and space-consuming space, in particular, a high-performance and expensive integrator with a fine lens pitch can be employed, the spatial distribution of illumination light on the irradiation surface can be made more uniform. .
For this reason, especially in a low-priced version projector, high image quality can be maintained while avoiding an increase in cost and size.

The arrangement of the LED elements of the LED array panel in the lighting device of the present invention is not limited to the above example. In the LED array panel 2 shown in FIG.
One surface 11a is divided into left and right sections 2a and 2b, and the LED elements 3 belonging to the sections 2a and 2b are arranged so that the angles around the optical axis differ by 90 degrees. Therefore, L of group G1 arranged in right section 2a
The ED elements 3 are all arranged such that the electrodes 3e are aligned diagonally left on the drawing. The LED elements 3 of the group G2 arranged in the left section 2b are all arranged such that the electrodes 3e are aligned diagonally right. For this reason, the LE of this example
Also in the D array panel 2, the same number of LED elements 3
The light is emitted from the array panel 2 and the spatial distribution on the irradiation surface is substantially uniform.

On the other hand, in each of the sections 2a and 2b, since the LED elements 3 are arranged so that the directions of the electrodes 3e are aligned, the wiring pattern becomes regular and simple, and the mounting becomes easy. Therefore, the rate of occurrence of defects such as wiring errors can be kept much lower, and the yield can be improved. For this reason, it is possible to provide an illumination device in which the spatial distribution of the emitted light is uniform and the illuminance non-uniformity of the screen does not appear when employed in a projector, at a lower cost.

In the above description, an example is shown in which the LED elements belonging to each group are arranged so as to be divided into two groups and have different angles around the optical axis, but are arranged in three or more groups. It is also possible. Also,
Although an example using a lamp-type LED element has been described above, the type of the LED element is not limited, and the present invention is applicable to an LED array panel equipped with another type of LED element such as a chip type. Applicable.

[0024]

As described above, in the lighting device of the present invention, the directions of the LED elements constituting the LED array panel, that is, the angles around the optical axis are not all aligned so that the electrical connection is easy. When the light emitted from the LED elements has a certain pattern of intensity distribution, the illumination light of the LED array panel on the illumination surface is formed as a whole by using the constant pattern emitted from the individual LED elements. Each LE so that there is no uniform illumination light
The D elements are arranged at different angles around the optical axis. Therefore, even if the LED array panel uses an LED element that shows a constant pattern in which the spatial intensity distribution of the emitted light is relatively strong, the LED array panel emits light that shows a substantially uniform illuminance distribution on the irradiation surface. Can be provided. For this reason,
By employing the LED array panel of the present invention, uniform illumination light can be output even if the integrator is omitted, and a compact and low-cost lighting device can be provided. Also, by employing the lighting device of the present invention,
It is possible to provide an image display device such as a compact and low-cost projector using an LED as a light source and capable of displaying a relatively high-quality image with less illuminance unevenness.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a projector using a lighting device according to the present invention.

FIG. 2 is a development view showing a schematic configuration of the lighting device shown in FIG.

FIG. 3 shows an LED in the LED array panel shown in FIG. 2;
FIG. 3 is a diagram showing a layout of an element.

FIG. 4 is a diagram showing an example of a layout of different LED elements.

FIG. 5 is a diagram showing an example of a projector using an LED array panel for a lighting device.

FIG. 6 shows an LED in the LED array panel shown in FIG.
FIG. 3 is a diagram showing a layout of an element.

[Explanation of symbols]

 1, 2, 100 LED array panel 3 LED element 3a LED element carrier 3b LED element reflection cone 3c Light emitting chip 3d LED element light emitting part 3e LED element electrode 4 Field lens 10,90 Illuminating device 18 Diffusing plate 19 Light collecting Lens 20 Liquid crystal panel (video display element) 28 Projection lens 30, 110 Projector 71 Optical axis of projector optical system 72 Optical axis of light emitting section of each LED element

Claims (7)

[Claims] An LED element for emitting light having an intensity distribution of a pattern rotationally symmetric about an optical axis is provided.
An LED array panel in which ED elements are aligned with each other at substantially the same optical axis and at an angle different by half of the rotationally symmetric rotation angle. 2. The LED array panel according to claim 1, wherein the rotationally symmetric pattern has two rotational symmetries. 3. The device according to claim 1, wherein the plurality of LED elements are arranged in a plurality of groups, and the LED elements belonging to each of the groups are arranged at the same angle around the optical axis. LED array panel. 4. The device according to claim 3, wherein the rotationally symmetric pattern has two rotational symmetries, and the LED elements belonging to the different groups are arranged at angles different by 90 degrees around the optical axis. LED array panel. 5. An illumination device comprising: the LED array panel according to claim 1; and a lens system that irradiates light emitted from the LED array panel to a unit that modulates intensity in pixel units. 6. The lighting device according to claim 5, further comprising a diffusion plate for diffusing light emitted from the LED array panel. 7. An image display device comprising: the illumination device according to claim 5; the modulating unit; and a lens system that projects the modulated light onto a screen.