JP2005266137A - Lighting system and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system which relieves uneven illuminance and uniformly and brightly illuminates a reflective element surface by arranging an integrator optical system at image points of a reduced image of a surface light source on which many LED elements are integrated and arranged in a surface lighting system. <P>SOLUTION: The lighting system has the surface light source 1 on which a plurality of light emitting parts are arranged like a plane, a first light condensing optical system which condenses light emitted from the surface light source 1, the integrator optical system 5 which uniformizes optical intensity distribution in a plane perpendicular to an optical axis of a light source image by the first light condensing optical system 4 and a second light condensing optical system 6 which condenses the light uniformized by the integrator optical system 5 as a second light source. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical system that illuminates a reflective element typified by DMD (Digital Micromirror Device), and more particularly to an optical apparatus that can irradiate a surface uniformly using a surface light source such as a number of LED elements.

In recent years, light emitting diodes (hereinafter referred to as LEDs) have been actively developed, and the brightness of recent LEDs has increased rapidly. Compared with bulb lamps such as xenon lamps and metal halide lamps, LEDs generally have advantages such as long life, high efficiency, high G resistance, and monochromatic light emission. For this reason, there is a tendency to shift from bulb lamps to LEDs as light sources for a wide variety of illumination or in their application fields.
For example, as a light source used for a projector, several kinds of bulb lamps are used such as a halogen lamp, a xenon lamp, a metal halide lamp, and an ultrahigh pressure mercury lamp. However, from the viewpoint of considering these bulb lamps as point light sources installed at the focal position of an elliptical mirror or a parabolic mirror, any bubble lamp can be regarded as the same light source.
On the other hand, when an LED is used as a light source using a reflective element typified by a DMD element, that is, when considering using the LED as a light source of a projector using the reflective element (hereinafter referred to as a reflective projector), the LED is Although there are advantages as described above compared with the bulb lamp, the amount of light emitted from the unit LED element is too small to be used as a point light source. For this reason, in recent years, in order to increase the amount of light emission, there has been a demand to arrange and arrange a large number of LED elements as one surface light source and use it as a light source for a reflective projector. However, the surface light source of this LED cannot be regarded as a point light source like a bubble lamp.
Conventionally, there are the following patent documents as related technologies regarding the light source of the optical system. For example, in Patent Document 1, as an optical system that handles light from a plurality of surface light sources, light emitted from the plurality of light sources is uniformly applied to the irradiated surface and at a minimum incident angle with respect to the irradiated surface. An illumination optical system for irradiating and an optical apparatus using the same are disclosed. Patent Document 1 has means for collimating light from a plurality of light sources. If the light from the plurality of light sources can be collimated, the size of the surface light source need not be considered.
Patent Document 2 discloses an apparatus using a bulb lamp and an elliptical mirror with respect to an image display apparatus using a reflective display element. However, when the LED element is applied to Patent Document 2, the arrayed LED element has a size and cannot be handled as a point light source, and thus cannot be used as a point light source for an elliptical mirror or a parabolic mirror, like a bulb lamp.
Patent Document 3 discloses an optical system that illuminates a spatial modulation element by making RGB light from a surface light source incident on a cross dichroic prism. In this case, the dichroic prism obtains a red component image, a green component image, and a blue component image by blinking the R, G, and B light sources, and displays a color image.
Furthermore, when an image of a surface light source composed of LED elements is formed on a reflective element using a single condensing optical system, there are the following problems.
1. When performing reduction image formation of a surface light source, the solid angle of illumination light becomes large. In the reflection type projector, it is necessary to separate the illumination light and the light focused on the screen so as not to interfere with each other, and there is a restriction on the solid angle of the illumination light.
2. When performing magnification imaging of a surface light source, the solid angle of the illumination light is reduced, but the image height is increased, and only a part of the light from the light source can illuminate the element.
3. Irradiance unevenness occurs.
JP 2002-184206 A JP 2002-268010 A Japanese Patent Laid-Open No. 11-65477

As described above, in order to obtain the amount of light emission, the LED element is a surface light source, and since it is a surface light source, the solid angle increases upon image formation. The problem is that only a part of the light can be used and uneven illuminance occurs. In the conventional apparatus, in order to form the light from the surface light source on the reflective element using the condensing optical system, it is necessary to prevent the illumination light and the imaging light from interfering with each other. There are restrictions on the solid angle.
From the viewpoint of a solid angle, when a device using a bulb lamp and an elliptical mirror is viewed, the image height becomes high, and only a part of the light from the light source can illuminate the element, so the problem of the solid angle of the illumination light remains. Even if the number of LED elements is increased to brightly illuminate the reflective element surface, the surface light source becomes large, and in order to form an image on the reflective element surface, it is necessary to reduce the lateral magnification of the condensing optical system. This is undesirable because it increases the solid angle of the illumination light.
In consideration of the above, a surface light source of an LED element is used, but an improvement is desired in which a solid angle is reduced and illuminance unevenness is eliminated without using a large surface light source that hardly collects light.
The present invention has been made in view of the above problems, and uses a surface light source in which a large number of LED elements are integrated and arranged so as to eliminate unevenness in illuminance and increase the solid angle of the reflective element surface that is the image plane. It is an object of the present invention to provide an illumination device and an image display device using the illumination device.

In order to achieve the above object, the invention described in claim 1 is a surface light source in which a plurality of light emitting portions are arranged in a plane, a first condensing optical system for condensing light emitted from the surface light source, An integrator optical system that makes the light intensity distribution in a plane perpendicular to the optical axis of the light source image by the one condensing optical system uniform, and a second light that condenses the light made uniform by the integrator optical system as a secondary light source An illumination device having a condensing optical system is the main feature.
The invention according to claim 2 is characterized in that, in the illuminating device according to claim 1, the illuminating device in which the light emitting portion is a light emitting diode is a main feature.
The invention according to claim 3 is the invention according to claim 1, wherein a plurality of surface light sources including a plurality of surface light sources in which a plurality of light emitting portions are arranged in a planar shape, a prism that combines light emitted from the plurality of surface light sources, A first condensing optical system that condenses the planar light synthesized by the prism, and an integrator optical system that makes the light intensity distribution in a plane perpendicular to the optical axis of the light source image by the first condensing optical system uniform. And a second condensing optical system that condenses the light made uniform by the integrator optical system as a secondary light source.
According to a fourth aspect of the present invention, in the illuminating device according to the third aspect, the prism is a cross dichroic prism, and each of the plurality of surface light sources is mainly an illuminating device composed of RGB single-color light emitting diodes.
The invention according to claim 5 is characterized in that, in the illumination device according to claim 1 or 3, the illumination device in which a lens is attached to each of the light emitting sections.
The invention according to claim 6 is characterized in that, in the illumination device according to claim 2 or 4, the light emitting diode has a radiation divergence narrow angle means for narrowing a radiation divergence full angle.

The invention according to claim 7 is the illumination device according to claim 1 or 3, wherein the lateral magnification β1 of the first condensing optical system is β1 ≦ 1, and the illumination device characterized in that To do.
The invention according to claim 8 is characterized in that, in the illumination device according to claim 1 or 3, the integrator optical system is a illumination device that is a rod lens.
The invention according to claim 9 is characterized in that, in the illumination device according to claim 1 or 3, the illumination device in which the lateral magnification β2 of the second condensing optical system is β2 ≧ 1.
According to a tenth aspect of the present invention, in the illuminating device according to the first or third aspect, the color filter that produces the three primary colors of light from white light with time is obtained by an image by the first condensing optical system or an integrator optical system. The main feature is an illuminating device characterized by having it in the vicinity of the uniformized light.
According to an eleventh aspect of the present invention, the inclination of a large number of micromirrors that are two-dimensionally arranged by the incident light of the second condensing optical system in the illumination device according to any one of the first to tenth aspects is changed. A reflection display means for creating an on / off state by changing the emission angle of the reflected light, and a projection lens for reflecting the reflected light from the micro mirror in the on state and projecting the incident light in an enlarged manner. The main feature is an image display device having the same.
According to a twelfth aspect of the present invention, there is provided a plurality of light reflecting surfaces on which the outgoing light of the second condensing optical system is incident and two-dimensionally arranged in the illumination device according to any one of the first to tenth aspects. Reflective display means that creates an on / off state by changing the exit angle of the reflected light by deforming both ends of the fixed beam, and the reflected light from the light reflecting surface in the on state is incident and the incident light is magnified and projected An image display device having a projection lens is a main feature.

According to the first and second aspects of the present invention, it is possible to obtain a uniform and powerful light multiple times that is obtained by superimposing a large number of uniform lights while maintaining a gentle solid angle. A practical lighting device can be obtained.
Further, according to the invention of claim 3, it is possible to obtain a uniform and powerful light multiple times that is obtained by superimposing a large number of uniform lights while maintaining a solid solid angle, and a single light source such as an LED is assembled. It becomes possible not only to obtain a practical lighting device, but also to obtain a practical lighting device with a wide range of applications that can freely combine light by a prism.
According to the inventions of claims 4 to 12, the light emitting section is provided with a lens, the light emitting diode is provided with a radiation divergence narrow angle means for narrowing the total radiation divergence angle, and the first condensing optical system Since the lateral magnification β1 is β1 ≦ 1, the integrator optical system is a rod lens, and the lateral magnification β2 of the second condensing optical system is β2 ≧ 1, it is practical with uniform light. It becomes possible to obtain a typical lighting device.
Furthermore, a practical image display apparatus can be obtained by providing a light modulation means using this illumination apparatus.

Hereinafter, the background to the completion of the present invention and embodiments of the present invention will be described with reference to the drawings.
(Background to the completion of the invention)
At present, when LED elements are used as light sources, a sufficient amount of light cannot be obtained unless a plurality of LED elements are arranged. For this reason, the arranged LED elements become a surface light source having a certain size.
FIG. 1 is an example in which a surface light source 1 in which LED elements are arranged in a square shape in the X direction (front and back direction in the drawing) and a Y direction is imaged by a condensing optical system, and the size of the surface light source 1 and the reflective element 2 is shown. The condensing optical system is arranged at the center of the surface light source 1 and the reflective element 2 with the same height. The solid angle A in the figure is determined by the specifications of the reflective element 2. That is, the usable range of the emitted light from the surface light source 1 is determined by the solid angle A. In FIG. 1, the size of the surface light source 1 is the same as that of the reflective element 2, and the solid angle also shows a gentle state as indicated by A. Further, in the configuration in which this condensing optical system is arranged, illuminance unevenness occurs on the reflective element 2, and therefore an integrator optical system is necessary in the optical system.
FIG. 2 shows an example using the surface light source 3 in which the size of the surface light source is doubled in both the X direction and the Y direction in order to illuminate the reflective element brightly. The area of the surface light source becomes four times brighter, but the lateral magnification of the condensing optical system is also reduced, and the solid angle B becomes B = 2 × A. It is not suitable for the specifications of element 2.
As a result, an optical system that collects light with the condensing optical system, reduces the solid angle, and eliminates illuminance unevenness with the integrator optical system is required.
(Embodiment of the present invention)
In an embodiment of the present invention, a reduced image of a surface light source in which a large number of LED elements are integrated and arranged is formed by a condenser lens that is a first condensing optical system, and an integrator optical system is disposed at this image point, thereby causing uneven illuminance. In addition, an illumination device that obtains a secondary light source from the light emitted from the integrator optical system and forms an image of the secondary light source on a reflective element through a condenser lens that is a second condensing optical system is obtained. By making a plurality of surface light sources with LED elements arranged and combining the light emitted from this surface light source with a prism to make a single surface light source, the reflective element surface is brightened with the same solid angle and without uneven illumination Can illuminate.

FIG. 3 shows an example of an illumination apparatus according to the first embodiment using the surface light source 1 and the reflective element 2. The optical system of Example 1 includes a surface light source 1, a condenser lens 4, a rod lens 5, a condenser lens 6, and a reflective element 2. Here, the lateral magnification β of the condenser lens 4 is set to 1/2 (at least β ≦ 1), and the lateral magnification β of the condenser lens 6 is set to 2 (at least β2 ≧ 1). Therefore, the solid angle of the surface light source 1 and the reflective element 2 remains A, and the incident light of the rod lens is reduced. Further, the rod lens 5 used as the integrator optical system is formed by hollowing out the inside of the quadrangular prism and using the inner surface as a reflecting mirror, and the size of the hollow surface is H5 = 1/2 × H1. Here, H1 represents the height from the center of the light source 1, and H5 represents the height from the center of the rod lens hollow surface.
The illuminating device according to the first embodiment has the same usable range of the light emitted from the light source as the illuminating device of FIG. 1 and the brightness remains the same, but the light source incident on the surface 151 of the rod lens 5 is the same. The light group that forms one reduced image is reflected a plurality of times inside the rod lens 5, so that the light intensity distribution is uniformized on the 152 surface of the rod lens 5, and this is used as a secondary light source. The surface on the reflective element 2 thus made has a uniform illuminance distribution and little illuminance unevenness.
Note that a color filter that produces the three primary colors of light from white light with time may be disposed in the vicinity of the image made by the condenser lens 4 or the light made uniform by the integrator optical system.
As a result of the above, it is possible to obtain an illuminating device having a solid angle of A with no illuminance unevenness.

FIG. 4 shows the second embodiment, which is the same as the first embodiment except for the surface light source. In the second embodiment, a cross dichroic prism 10 is arranged instead of the surface light source 1 in the first embodiment. The cross dichroic prism 10 that is a light source is formed by bonding four prismatic prismatic right-angle prisms with their ridges aligned so that the prism apex angles intersect, and a dichroic surface is attached to the joint surface of each prism. It is provided. With respect to the dichroic surface, if the four right-angle prisms are 11, 12, 13, and 14, respectively, the joint surface a of the prisms 11 and 12 and the joint surface c of the prisms 13 and 14 are green (G light) reflected by blue (B light). A dichroic surface ac that transmits light) and red (R light) is formed, and a dichroic surface bd that transmits G light and B light by R light reflection on the joint surface d of the prisms 12 and 13 and the joint surface b of the prisms 14 and 11. Is given. Here, as shown in FIG. 4, the surface light source 7 is disposed parallel to the prism 12, the surface light source 8 is disposed parallel to the prism 13, and the surface light source 9 is disposed parallel to the prism 14. The surface light source 7 has red LED elements arranged in a square in the X direction and the Y direction, the surface light source 8 has a green color, and the surface light source 9 has a blue LED element similarly arranged.
Accordingly, the R light from the incident surface (non-joint surface) S2 of the prism 12, the G light from the incident surface (non-joint surface) S3 of the prism 13, and the B light from the incident surface (non-joint surface) S4 of the prism 14 are emitted. Incident light is emitted from the exit surface (non-joint surface) S <b> 1 of the prism 11. In the second embodiment, the surface S1 of the prism 11 is used as a surface light source, and a bright surface light source can be obtained as compared with the first embodiment. However, when the light emitted from each surface light source diffuses and the light does not collect on the S1 surface, a radiation divergence full-angle narrow-angle means for attaching a lens to each light-emitting section and narrowing the radiation divergence full-angle to the light-emitting diode This problem can be avoided by installing.
FIG. 5 shows the arrangement state of each optical element by taking FIG. 1 as an example, but the arrangement of the optical elements in FIGS. 3 and 4 is similarly configured.

FIG. 6 shows a simplified configuration diagram in which an image display device is configured by an illumination device using the optical system shown in FIGS. 3 and 4. Here, the surface light source 1 in which the LEDs shown in FIG. 3 are arranged as the light source 20 or the light source comprising the cross dichroic prism 10 shown in FIG. 4 is used, and reflective display means corresponding to the reflective element 2 shown in FIGS. DMD is used as 30. This DMD has a structure in which a large number of micromirrors are arranged in a planar shape, and each micromirror as a pixel is configured to change (turn) about ± 10 ° by electrical control. Then, by changing the tilt angle of the micromirror, it functions as an optical modulator, and the on / off state of the micromirror can be obtained. That is, the light incident on the DMD from the light source 20 passes through the projection lens 40 when the micromirror is turned on to project an image on the screen 50, and is not irradiated on the screen 50 when the micromirror is turned off. (Not shown).
FIG. 7 shows another example of the light modulation element constituting the reflective display means 30. In this light modulation element, a gap made of, for example, a V-groove 32 is formed by etching or the like on the substrate 31, a beam 33 made of a thin film is formed so as to bridge the gap, and a light reflecting film that is flat on the beam 33 When the voltage is not applied to the electrode of the substrate, the planar light reflecting film 34 is formed. By applying a voltage to the electrode, the beam 33 and the light reflecting film 34 are formed into a V-groove shape. The operation of deforming is performed. Here, light incident at an oblique incident angle with respect to the substrate can be obtained as oblique outgoing light with a reflection angle equal to the incident angle by the planar light reflection film 34 when no voltage is applied. When the light reflecting film 34 is deformed in accordance with the application of light, incident light oblique to the substrate is obtained as, for example, outgoing light perpendicular to the substrate, and the light reflecting film is controlled by controlling the applied voltage. Light modulation is performed by changing the reflection direction of the incident light that is reflected. If the reflective display means 30 is configured by arranging a large number of such light modulation elements as pixels, the reflective display means 30 similar to that in FIG. 6 can be obtained.

It is explanatory drawing of the example which imaged the conventional square LED element arrangement | sequence surface light source by the optical system by equal magnification. It is explanatory drawing of the example of the surface light source which doubled the magnitude | size of the conventional surface light source in both directions. It is a structure sectional view of the illuminating device using the surface light source and reflective element of this invention. It is a structure sectional view of the example using the cross dichroic prism of the present invention. It is a perspective view for explanation of composition of an optical system concerning the present invention. It is a simplified block diagram of an image display apparatus. It is a cross-sectional block diagram of an example of a reflective display means.

Explanation of symbols

  1 surface light source, 2 reflective element, 3, 7, 8, 9 surface light source, 4, 6 condenser lens, 5 rod lens, 10 cross dichroic prism, 11, 12, 13, 14 right angle prism, 20 light source, 30 reflective display Means, 40 projection lens, 50 screen

Claims (12)

  A surface light source in which a plurality of light emitting portions are arranged in a plane, a first condensing optical system for condensing light emitted from the surface light source, and an in-plane orthogonal to the optical axis of the light source image by the first condensing optical system An illuminating apparatus comprising: an integrator optical system that makes the light intensity distribution of the light uniform; and a second light collecting optical system that collects the light made uniform by the integrator optical system as a secondary light source.   2. The lighting device according to claim 1, wherein the light emitting unit is a light emitting diode.   A multi-surface light source having a plurality of surface light sources in which a plurality of light emitting portions are arranged in a plane, a prism that combines light emitted from the multi-surface light source, and a first light that condenses the light combined by the prism 1 condensing optical system, an integrator optical system for uniforming the light intensity distribution in a plane perpendicular to the optical axis of the light source image by the first condensing optical system, and light made uniform by the integrator optical system as a secondary light source And a second condensing optical system for condensing the light.   4. The illuminating device according to claim 3, wherein the prism is a cross dichroic prism, and each of the plurality of surface light sources is composed of a light emitting diode of RGB single color.   The lighting device according to claim 1 or 3, wherein a lens is attached to each of the light emitting units.   5. The lighting device according to claim 2, wherein the light emitting diode has a radiation divergence narrow angle means for narrowing a radiation divergence full angle. In the illumination device according to claim 1 or 3, the lateral magnification β1 of the first condensing optical system is:
β1 ≦ 1
A lighting device characterized by the above.   4. The illumination device according to claim 1, wherein the integrator optical system is a rod lens. In the illumination device according to claim 1 or 3, the lateral magnification β2 of the second condensing optical system is:
β2 ≧ 1
A lighting device characterized by the above.   4. The illumination device according to claim 1, wherein a color filter that produces three primary colors of light from white light with time is provided in the vicinity of the image made uniform by the first condensing optical system or the integrator optical system. A lighting device characterized by that.   The outgoing light of the second condensing optical system in the illumination device according to any one of claims 1 to 10 is incident, and an inclination angle of a number of micromirrors arranged two-dimensionally is changed to change an outgoing angle of the reflected light. An image display comprising: reflective display means for creating an on / off state by changing; and a projection lens for reflecting light incident from a micromirror in the on state and projecting the incident light in an enlarged manner apparatus.   11. The both ends fixed beam which has many light-reflecting surfaces in which the emitted light of the 2nd condensing optical system in the illuminating device in any one of Claim 1 to 10 injects, and two-dimensionally arranged is deformed, and reflected light Reflection display means for creating an on / off state by changing the emission angle of the light source, and a projection lens for reflecting the reflected light from the light reflecting surface in the on state and projecting the incident light in an enlarged manner. A characteristic image display device.

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