JP2006301114A - Illumination device and picture display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device restraining speckle noise from being produced without lowering the efficiency of using light even when a semiconductor laser is used as the light source of the illumination device, and a picture display device. <P>SOLUTION: The illumination device includes: at least one light source to emit coherent light; the light source to emit incoherent light; a color discriminating member; and a driving part to drive the color discriminating member, and is constituted to provide a diffusion part for the coherent light in the color discriminating member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an illumination device and an image display device using the same, and more particularly to an illumination device and an image display device using a coherent light source.

  For example, a spatial light modulation element such as a liquid crystal panel or DMD (digital micromiror device) element is illuminated by a lighting device, and transmitted light or reflected light from the spatial light modulation element is projected onto a screen by a projection lens. An image display device (optical projector) is known. As the light source of the illumination device in such an image display device, a high-intensity discharge lamp such as an ultrahigh pressure mercury lamp is mainly used. However, ultra-high pressure mercury lamps, etc., have a small amount of red wavelength component, so in order to achieve a white balance in the projected image, it is necessary to suppress the amount of wavelength components of other colors (green and blue), resulting in high brightness. Even with this lamp, light cannot be used efficiently. For this reason, in a device using a high-intensity lamp as a light source, it is known to use a red light-emitting diode as a light source in order to compensate for the amount of red light (Patent Document 1).

In addition, an attempt has been made to use a semiconductor laser as a light source of an illumination device. The semiconductor laser has a practically sufficient life, and the monochromaticity of the emitted light is good, so that a large color reproduction region can be realized. However, since the emitted light from the semiconductor laser has high coherence (coherence), it interferes with each other, and when the semiconductor laser is used as the light source of the illumination device of the image display device, it is random. A change in intensity, that is, speckle noise is formed on the screen, resulting in a reduction in the image quality of the display image. For this reason, when a semiconductor laser is used as the light source of an illumination device, a method of reducing speckle noise by reducing coherence by inserting a diffusing element or the like in the optical system and disturbing the wavefront of the laser light is known. (See Patent Document 2).
JP 2000-305040 A JP-A-6-208089

In a lighting device that uses a high-intensity lamp as a light source, when a red semiconductor laser is used together to compensate for the amount of red wavelength component, speckle noise is formed on the screen, resulting in a reduction in image quality of the displayed image. Problem arises.
Also, when using multiple color lasers (red laser, blue laser, green laser) as the light source of the illumination device, if the same diffusing element is used for the purpose of reducing the coherence of the emitted light of each laser, The laser light is diffused in all directions under the same conditions. That is, there is a problem in that the use efficiency of light is reduced for a laser of a specific color, and the amount of emitted light is reduced, resulting in a reduction in the image quality of the display image.

  In consideration of the above-described points, the present invention provides an illuminating device in which generation of speckle noise is suppressed without lowering light utilization efficiency and even when a semiconductor laser is used as a light source of the illuminating device. An image display device is provided.

  An illumination device according to the present invention includes at least one light source that emits coherent light, a light source that emits incoherent light, a color identification unit, and a drive unit that drives the color identification unit, The identification unit is provided with a diffusion unit for the coherent light.

Preferably, it is appropriate that the color identification unit is provided with a region corresponding to coherent light and a region corresponding to incoherent light, and the diffusion unit is provided only in a region for coherent light.
Preferably, the maximum value of the angle of the coherent light emitted from the color identification unit is larger than the maximum value of the angle of the coherent light incident on the color identification unit.
Preferably, it is appropriate that the angle of the coherent light emitted from the color identification unit and the angle of the incoherent light emitted from the color identification unit are substantially the same.
More preferably, it is appropriate that the color identification unit is provided on an optical path through which the coherent light and the incoherent light pass.

  An illumination device according to the present invention includes at least one light source that emits coherent light, a color identification unit, and a drive unit that drives the color identification unit, and the color identification unit includes a diffusion unit for the coherent light. It is provided.

  As described above, this illuminating device can cause speckle noise to move around on the screen after passing through the light modulation element or the projection lens at high speed by diffusing the coherent light by the diffusion unit.

  An image display device according to the present invention includes an optical modulator that modulates light, a projection unit that projects light to display an image, a light source that emits incoherent light, and at least one that emits coherent light. A light source, a color identification unit, and a drive unit that drives the color identification unit are provided, and a diffusion unit for the coherent light is provided in the color identification unit.

  As described above, this image display device diffuses coherent light by the diffusion unit, thereby moving speckle noise on the screen after passing through the light modulation element or the projection lens at a high speed, thereby obtaining a high-quality image. Can be displayed.

  According to the lighting device of the present invention, it is possible to provide lighting that has good color reproducibility, good white balance, is small, and can suppress generation of speckle noise.

  According to the image display device of the present invention, it is possible to display a high-quality image that has good color reproducibility and white balance, is small, and suppresses speckle noise.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1
FIG. 1 is a schematic configuration diagram of an illumination device 20 according to the first embodiment of the present invention.
As shown in FIG. 1, the illumination device 20 includes a light source 1 that emits coherent light, a light source 2 that includes a reflector 2 a that emits incoherent light, and a discharge lamp 2 b, lenses 3 and 9, a dichroic mirror 4, and a common optical path 5. , A drive unit 6, a color wheel 7, an integrator 8, a mirror 10, a light modulation element 11, and a projection lens 12.

  Here, the coherent light means light having a pure wavelength and high phase coherence, and the incoherent light means light having various wavelengths mixed and random in phase. In the present embodiment, a semiconductor laser in the red wavelength band is used as the light source 1 that emits coherent light, and an ultrahigh pressure mercury lamp is used as the light source 2 that emits incoherent light. For example, a xenon lamp, a metal halide lamp, or a high-pressure mercury lamp may be used as the light source 2.

FIG. 2 is an overall view of the color wheel 7 which is a color identification member as a color identification unit used in the present embodiment.
The color wheel 7 is formed in a disc shape, and red, green, and blue color filters are provided on the disc surface. The surface of the color wheel 7 is equally divided into six, and the color filters of the respective colors are arranged so as to be symmetric. The regions R1 and R2 provided with the red color filter are regions that transmit the red wavelength band and reflect the wavelength bands of other colors, and the regions G1 and G2 provided with the green color filter are the green wavelength band. The regions B1 and B2 where the blue color filter is provided are regions that transmit the blue wavelength band and reflect the wavelength bands of the other colors. The regions R1 and R2 are provided with a diffusion layer 7c for diffusing transmitted red light. The color wheel 7 is an example of a color identification member.

3A is a cross-sectional view when the color wheel 7 shown in FIG. 2 is cut along line XX, and FIG. 3B is a cross-sectional view when the color wheel 7 shown in FIG. 2 is cut along line YY. is there.
FIG. 3A shows a cross-sectional view of the regions G1, G2, B1, and B2. The regions G1, G2, B1, and B2 of the color wheel 7 are formed on the light transmissive substrate 7b by sputtering or the like. It is formed by providing the layer 7a. FIG. 3B shows a cross-sectional view of the regions R1 and R2. A dichroic filter layer 7a, which is a color identification layer, is provided on the light transmissive substrate 7b by sputtering or the like, and the dichroic of the light transmissive substrate 7b. A diffusion layer 7c is formed on the surface facing the surface on which the filter layer 7a is provided. The diffusion layer 7c may be formed by roughening the surface by etching, or may be formed by attaching a seal having a rough surface.

  FIG. 4 shows an example of the optical characteristics of the diffusion layer used in this embodiment. FIG. 4A schematically shows the state of light incident on and scattered by the diffusion layer 7c. The graph of FIG. 4B illustrates the relationship between the diffusion angle and the intensity ratio when light enters the diffusion layer perpendicularly. In the case of FIG. 4B, the component emitted perpendicularly to the normal incidence is the largest, and the relative intensity with respect to the vertical emission decreases as the scattering angle increases. On the other hand, the graph of FIG. 4C illustrates the relationship between the diffusion angle and the intensity ratio when an optical element that diffuses vertically incident light with the same intensity in a range of ± 1 / 2θc ′ is used. As an optical element as shown in FIG. 4B, for example, there is a diffuser in which a hologram pattern is formed, and as an optical element as shown in FIG. 4C, there is an element using so-called diffraction.

  As shown in FIG. 1, the coherent light beam emitted from the red semiconductor laser light source 1 and the incoherent light beam emitted from the ultrahigh pressure mercury lamp light source 2 are incident on the dichroic mirror 4 and synthesized. The light synthesized by the dichroic mirror 4 passes through a common optical path 5 and enters a disk-shaped color wheel 7. The color wheel 7 is rotated at a speed of about 300 Hz by the motor 6 of the drive unit, and separates the incident combined light into light of red, green, and blue wavelength bands in a time division manner. Light rays emitted from the color wheel 7 enter the integrator 8, are repeatedly reflected to become uniform light, and enter the lens 9. The light incident on the lens 9 is collected by the lens 9 and then reflected by the mirror 10 to enter the reflective light modulation element 11. The DMD element as the reflective light modulation element 11 corresponds to the light in the red, green and blue wavelength bands separated by the color wheel 7 according to the R, G and B signals output from the control means (not shown). Driven to split. When the DMD element is in the ON state, the reflected light from the mirror 10 enters the projection lens 12 and is projected onto a screen (not shown). When the DMD element is in the OFF state, the reflected light from the mirror 10 does not enter the projection lens 12. In this manner, light in the red, green, and blue wavelength bands modulated according to the levels of the R, G, and B signals is sequentially projected onto the screen, whereby a color image is displayed on the screen. Such a display method is called a field sequential method.

  Of the combined light incident on the color wheel 7, the light beam in the green wavelength band, which is incoherent light, passes through the regions G1 and G2 provided on the surface of the color wheel 7, and the light beam in the blue wavelength band is in the region B1. , B2 is transmitted.

  Of the combined light incident on the color wheel 7, the light flux in the red wavelength band of the coherent light is diffused by the diffusion layer 7 c in the regions R <b> 1 and R <b> 2 when passing through the color wheel 7. Further, since the color wheel 7 rotates at a high speed as described above, the diffusion layer 7c also rotates at a high speed. Thereby, the interference pattern generated by the light in the red wavelength band, which is coherent light, is split, and this interference pattern, that is, speckle noise, is reflected on the reflection type light modulation element 11 and further on the screen after passing through the projection lens 12. Will move around at high speed. Thereby, the flicker of the image resulting from speckle noise is averaged, and a high-definition image can be realized.

In this way, according to the lighting apparatus according to the present embodiment, it is possible to obtain red, blue, and green light amounts necessary for white balance by supplementing the light amount of the red wavelength component. Also, by supplementing the light quantity of the red wavelength component, the color reproducibility can be broadened, and illumination that can suppress the generation of speckle noise even when a red semiconductor laser is used. Can be provided. In addition, since a semiconductor laser is used as a means for compensating the light amount of the red wavelength component, Etendue (light source area × solid emission angle / refractive index of light source) when a light beam is incident on a DMD element or a liquid crystal panel is used. (Square) can be reduced, and light can be collected more efficiently. In general, the light emitting surface of a light emitting diode having a light output of about 500 mW has an area of about 1 mm ² , whereas in the case of a semiconductor laser, it is as small as several tens of μm ² to several thousand μm ² . When a semiconductor laser is used, a very small etendue can be obtained.

  FIG. 5A is a schematic diagram of an optical path of incoherence light according to the present embodiment, and FIG. 5B is a schematic diagram of an optical path of coherence light.

  FIG. 5A illustrates light rays from an ultrahigh pressure mercury lamp 2 that is an incoherence light source. The reflector 2a of the ultra-high pressure mercury lamp 2 has an elliptical shape, and the discharge lamp 2b is located in the vicinity of the focal point. The light beam emitted from the lamp 2 b is reflected by the reflector 2 a, passes through the dichroic mirror 4, and then enters the color wheel 7. In this case, the angle of the light beam incident on the color wheel 7 with respect to the optical axis is defined as the angle of the incoherent light incident on the color wheel 7, and the maximum incident angle is θic.

  On the other hand, as shown in FIG. 5B, the light beam emitted from the laser 1, which is a coherent light source, is collected by passing through the lens 3, reflected by the dichroic mirror 4, and incident on the color wheel 7. In this case, the angle of the light beam incident on the color wheel 7 with respect to the optical axis is defined as the angle of the coherent light incident on the color wheel 7, and the maximum incident angle is θc.

  In the present embodiment, an optical system such as the lens 3 and the dichroic mirror 4 is arranged so that the relationship between the maximum incident angle θic of the incoherent light source and the maximum incident angle θc of the coherent light satisfies θic> θc.

  By adopting such an arrangement, the exit angle of the incoherent light after passing through the color wheel 7 becomes θic, which is not different from the angle at the time of incidence, but the exit angle of the coherent light is diffused by the diffusion unit 7c. Therefore, as shown in FIG. 5B, the maximum angle θc ′ after transmission has a relationship of θc ′> θc.

  In the present embodiment, the optical element such as the dichroic mirror 4 is disposed so that the maximum angle θic of the incoherent light after passing through the dichroic mirror 4 and the maximum angle θc ′ of the coherent light are close to each other. Since the optical member is arranged so that the maximum angle of the light emitted from the dichroic mirror 4 is substantially the same between the coherent light and the incoherent light, the incident angle distribution of the light beam incident on the light modulation element 11 is obtained. It can be the same for coherent light and incoherent light. This makes it possible to reduce unevenness such as contrast due to the incident angle characteristic of the light incident on the reflective light modulation element 11, and to realize a high-quality image.

Embodiment 2
Next, Embodiment 2 of the illumination device of the present invention will be described with reference to FIG. FIG. 6 is a schematic configuration diagram of an illumination apparatus according to the second embodiment of the present invention.

  As shown in FIG. 6, the illumination device 30 of the second embodiment is the same as that of the first embodiment except for the vicinity of the light source of coherent light and the color wheel 17. In the present embodiment, a semiconductor laser 1a in the red wavelength band and a semiconductor laser 1b in the blue wavelength band are used as light sources that emit coherent light. A dichroic mirror 13 is disposed between the light sources 1 a and 1 b for coherent light and the dichroic mirror 4.

  The dichroic mirror 13 reflects light in the wavelength band of the red laser 1a and transmits light in the wavelength band of the blue laser 1b. Therefore, the light beams emitted from the lasers 1a and 1b are combined and incident on another dichroic mirror 4. In the dichroic mirror 4, all the combined laser beams are reflected and travel toward the color wheel 17 of the color identification member.

  On the other hand, when light emitted from the high-pressure mercury lamp 2 that is incoherent light enters the dichroic mirror 4, light in a part of the wavelength band is transmitted and light in other wavelength bands is reflected. The wavelength band to be transmitted differs depending on the performance required for the display, product planning, etc., but in the second embodiment, for example, light in the green wavelength band, part of the light in the blue wavelength band, red wavelength A portion of the band of light is transmitted. The light beam that has passed through the dichroic mirror 4 enters the color wheel 17.

FIG. 7 is an overall view of the color wheel 17 as a color identification member used in the second embodiment.
As shown in FIG. 7, the color wheel 17 is formed in a disk shape, and red, green, and blue color filters are provided on the disk surface. The surface of the color wheel 17 is divided into a plurality of parts, and the color filters of the respective colors are arranged so as to be symmetric. The regions R1 and R2 provided with the red color filter are regions that transmit the red wavelength band and reflect the wavelength bands of other colors, and the regions G1 and G2 provided with the green color filter are the green wavelength band. The regions B1 and B2 where the blue color filter is provided are regions that transmit the blue wavelength band and reflect the wavelength bands of the other colors. The regions R1 and R2 are provided with a diffusion layer for diffusing the transmitted red light. Further, a diffusion layer for diffusing the transmitted blue light is provided in the regions B1 and B2. The structure of the color wheel 17 in the portion where the diffusion layer is provided is the same as that of the color filter 7 of the first embodiment shown in FIG.

  In this way, the luminous flux in the green wavelength band, which is incoherent light among the combined light incident on the color wheel 17, passes through the regions G <b> 1 and G <b> 2 provided on the surface of the color wheel 17. Of the combined light incident on the color wheel 17, the light flux in the red wavelength band of the coherent light is diffused by the diffusion layers in the regions R <b> 1 and R <b> 2 when passing through the color wheel 17. The light beam is diffused by the diffusion layers in the regions B1 and B2. As described above, since the color wheel 17 rotates at high speed, the diffusion layer portion also rotates at high speed, so that the interference pattern generated by the red wavelength band light and the blue wavelength band light, which are coherent light, is split. Thus, this interference pattern, that is, speckle noise is moved around at high speed on the reflection type light modulation element 11 and also on the screen after passing through the projection lens 12. As a result, the image flicker caused by speckle noise is averaged, and a high-quality image can be realized.

Embodiment 3
Next, Embodiment 3 of the illumination device of the present invention will be described with reference to FIG. FIG. 8: is a schematic block diagram of the illuminating device concerning Embodiment 3 of this invention.
As shown in FIG. 8, the illumination device 40 of the third embodiment is the same as that of the first embodiment except for the vicinity of the light source of coherent light and the color wheel 27.

  In the present embodiment, a semiconductor laser 1R in the red wavelength band, a semiconductor laser 1B in the blue wavelength band, and a semiconductor laser 1G in the green wavelength band are used as light sources that emit coherent light. Further, between the semiconductor lasers 1R, 1G, and 1B and the color wheel 27, a mirror 4R and dichroic mirrors 4G and 4B are disposed so as to face the semiconductor lasers 1R, 1G, and 1B.

  The mirror 4R reflects light in the wavelength band of the red laser 1R, and the dichroic mirror 4G reflects green of the green laser 1G and transmits red. The dichroic mirror 4B reflects the blue color of the blue laser 1B and transmits red and green. Therefore, the light beams emitted from the coherent light sources 1R, 1G, and 1B are combined and enter the color wheel 27.

  FIG. 9 is an overall view of the color wheel 27 as a color identification member used in the third embodiment.

  As shown in FIG. 9, the color wheel 27 is formed in a disc shape, and red, green, and blue color filters are provided on the disc surface. The surface of the color wheel 27 is equally divided into six, and the color filters of the respective colors are arranged so as to be symmetric. The regions R1 and R2 provided with the red color filter are regions that transmit the red wavelength band and reflect the wavelength bands of other colors, and the regions G1 and G2 provided with the green color filter are the green wavelength band. The regions B1 and B2 where the blue color filter is provided are regions that transmit the blue wavelength band and reflect the wavelength bands of the other colors. The regions R1 and R2 are provided with a diffusion layer 7c for diffusing transmitted red light, and the regions B1 and B2 are provided with a diffusion layer 7c for diffusing transmitted blue light. Further, a diffusion layer 7c for diffusing the transmitted green light is also provided in the regions G1 and G2. The structure of the color wheel 27 in the portion where the diffusion layer is provided is the same as that of the color filter 7 of the first embodiment shown in FIG.

Moreover, you may make it change the spreading | diffusion degree of the diffusion layer 7c provided in the filter of each color as needed. For example, the diffusion degree of the diffusion layers provided in the regions G1 and G2 for green with high visibility is set higher than the diffusion degree of the diffusion layers provided in the other color regions R1, R2, B1, and B2. The diffusion layers 7c for the green regions G1 and G2 may be formed.
Furthermore, it is conceivable that the maximum value of the angle at which each light source is incident on the color wheel 27 is different due to the difference in the characteristics of the red, blue, and green light sources. In order to adjust the diffusion angle, the degree of diffusion of each diffusion layer may be changed.

  By doing so, the light flux in the red wavelength band of the coherent light incident on the color wheel 27 is diffused by the diffusion layers in the regions R1 and R2 when passing through the color wheel 17, and the light flux in the blue wavelength band of the coherent light. Is diffused by the diffusion layers in the regions B1 and B2, and the light flux in the green wavelength band of the coherent light is diffused by the diffusion layers in the regions G1 and G2. As described above, since the color wheel 27 rotates at a high speed, the diffusion layer portion also rotates at a high speed, so that the red wavelength band light, the blue wavelength band light, and the green wavelength band light that are coherent light are used. The generated interference pattern is divided, and this interference pattern, that is, speckle noise is moved around on the reflection type light modulation element 11 and also on the screen after passing through the projection lens 12 at high speed. As a result, the image flicker caused by speckle noise is averaged, and a high-quality image can be realized.

  Further, as shown in FIG. 10, instead of the light sources 1R, 1G, and 1B of the illumination device of the third embodiment, a semiconductor in which red, blue, and green wavelength lasers are mounted in one place as a light source that emits coherent light. Lasers 1RGB may be used. As a result, the laser light of each color can be directly incident on the color wheel 27, and the dichroic mirror can be eliminated.

  In the above embodiment, an ultra-high pressure mercury lamp is used as the incoherent light source. However, the present invention is not limited to this, and a halogen lamp, a xenon lamp, an LED, or the like may be used. The color wheel used in the embodiment is all divided into six regions, but is not limited to this. For example, the color wheel may be divided into three, four, or ten. Further, the area provided in the color wheel does not need to be equally divided and may be unevenly divided. Further, although a dichroic mirror is used as the light combining means, a hologram element, PBS (polarization beam splitter), or the like may be used. Further, although DMD is used as the light modulation element, the present invention is not limited to this, and a reflective liquid crystal element, a transmissive liquid crystal element, other light modulation elements, or the like may be used.

FIG. 1 is a schematic configuration diagram of an illumination apparatus according to the first embodiment of the present invention. FIG. 2 is an overall view of the color wheel used in the first embodiment. 3A is a sectional view taken along line XX of the color wheel shown in FIG. 2, and FIG. 3B is a sectional view taken along line YY. FIG. 4A is a diagram schematically illustrating the state of light incident on and scattered by the diffusion layer, and FIGS. 4B and 4C are graphs showing examples of optical characteristics of the diffusion layer used in the present embodiment. is there. FIG. 5A is a schematic diagram of an optical path of incoherence light according to the present embodiment, and FIG. 5B is a schematic diagram of an optical path of coherence light. FIG. 6 is a schematic configuration diagram of an illumination apparatus according to the second embodiment of the present invention. FIG. 7 is an overall view of a color wheel used in the second embodiment. FIG. 8: is a schematic block diagram of the illuminating device concerning Embodiment 3 of this invention. FIG. 9 is an overall view of the color wheel used in the third embodiment. FIG. 10 is a schematic configuration diagram of an illumination device according to another embodiment.

Explanation of symbols

1..Laser light source, 2..Lamp light source, 3,9..Lens, 4,13..Dichroic mirror, 5..Optical path, 6..Drive means, 7,17..Color wheel, 7a..Dichroic Filter layer, 7b ... Light transmissive substrate, 7c ... Diffusion layer, 8 ... Integrator, 10 ... Mirror, 11 .... Light modulation element, 12 .... Projection lens, 20, 30, 40, 50 ... Illumination apparatus

Claims (8)

At least one light source that emits coherent light;
A light source that emits incoherent light;
A color identification unit;
A drive unit for driving the color identification unit,
An illumination device, wherein a diffuser for the coherent light is provided in the color identification unit. The color identification unit is provided with a region corresponding to coherent light and a region corresponding to incoherent light,
The lighting device according to claim 1, wherein the diffusing unit is provided only in a region for coherent light. The illumination device according to claim 2, wherein the maximum value of the angle of the coherent light emitted from the color identification unit is larger than the maximum value of the angle of the coherent light incident on the color identification unit. The illumination device according to claim 2, wherein the angle of the coherent light emitted from the color identification unit and the angle of the incoherent light emitted from the color identification unit are substantially the same.   The illumination device according to claim 2, wherein the color identification unit is provided on an optical path through which the coherent light and the incoherent light pass. At least one light source that emits coherent light;
A color identification unit;
A drive unit for driving the color identification unit,
An illumination device, wherein a diffuser for the coherent light is provided in the color identification unit. The illumination device according to claim 6, wherein the maximum value of the angle of the coherent light emitted from the color identification unit is larger than the maximum value of the angle of the coherent light incident on the color identification unit. A light modulation element for modulating light;
A projection unit for projecting light to display an image;
A light source that emits incoherent light;
At least one light source that emits coherent light;
A color identification unit;
A drive unit for driving the color identification unit,
An image display device, wherein the color identification unit is provided with a diffusion unit for the coherent light.

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