JP2008180839A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of obtaining an image having little irregular luminance and irregular color when projecting a low-luminance image generating optional wavelength light to a screen. <P>SOLUTION: The projector includes: a light source constituted of an R light source 1, a G light source 2 and a B light source 3; a color mixing device 4 emitting respective luminous fluxes made incident from the respective light sources such as the R light source 1, the G light source 2 and the B light source 3 as single light; and an R light shielding curtain 5 corresponding to the R light source 1, a G light shielding curtain 6 corresponding to the G light source 2, and a B light shielding curtain 7 corresponding to the B light source 3, wherein these light shielding curtains 5 to 7 are arranged between the light source constituted of the R light source 1, the G light source 2 and the B light source 3, and the color mixing device 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projector, and more particularly to a projector including a light-shielding curtain that shields light from a light source.

  The projector has a configuration in which light from a light source is modulated by a video device and then projected onto a screen by a projection lens. As a method for adjusting the contrast of an image projected on a screen in a conventional projector, a shutter device that improves the contrast by installing a light-shielding curtain in the optical path from a light source to a projection lens is generally known. When a relatively dark image is displayed using this light-shielding curtain, the amount of light is limited by the light-shielding curtain to make the display image darker, and when a relatively bright image is displayed, the light-shielding curtain limits The display image on the screen is brightened by not performing the above. High pressure mercury lamps, metal halide lamps, LEDs, lasers, etc. are used as the light source. Especially, LEDs and lasers are composed of multiple light sources, and white light is obtained by mixing multiple light colors. ing.

  As a method of limiting the light amount of the light source, a method of limiting the light amount of the light source itself is conceivable. However, depending on the type of the light source, it is often difficult to limit the light amount of the light source itself for reasons of performance and reliability. Therefore, a method of limiting the amount of light by installing a light-shielding curtain in any one of the optical paths from the light source to the projection lens has become common. The light shielding curtain controls the amount of light emitted from the light source through the display device to the projection lens by changing the light shielding area with respect to the light beam. However, increasing the light-shielding area by the light-shielding curtain in order to greatly reduce the amount of light will impair the uniformity of the light and make the intensity of the light projected on the screen non-uniform. On the other hand, there is a problem that the luminance is partially lowered without obtaining a uniform luminance distribution. Also, in projectors with a configuration that obtains white light by mixing light sources of multiple colors, if the light shielding area of the light shielding curtain is increased, the area through which light of each color can be transmitted decreases, so that light is not shielded Compared to, the ratio and distribution of the light of each color to be transmitted changes, and a sufficiently mixed white light cannot be obtained, resulting in partial color unevenness in the image projected on the screen or the intended color. There was a problem such as an image different from the temperature.

  For these problems, by placing an optical diaphragm that functions as a light-shielding curtain at the position of the entrance pupil of the projection optical system, at a position where the area of the surface perpendicular to the optical axis of the projected light is the smallest In some cases, only unnecessary stray light is projected while being blocked (see, for example, Patent Document 1). In addition, there is a case where luminance unevenness is reduced by arranging two light shielding plates so as to face each other with the optical axis as a center to perform light shielding (see, for example, Patent Document 2).

Japanese Patent Laying-Open No. 2005-300899 (page 17, FIG. 3) Japanese Unexamined Patent Publication No. 2004-69966 (page 19, FIG. 16)

  However, neither Patent Document 1 nor Patent Document 2 specifically considers the case where the light source is composed of a plurality of light sources. In such a case, effective light quantity control is not always possible.

  The present invention has been made to solve these problems. When the light source is composed of a plurality of light sources, effective light amount control is possible, and when a low-luminance image is projected on the screen, It is an object of the present invention to provide a projector capable of obtaining an image with less luminance unevenness and color unevenness.

  In order to solve the above problems, a projector according to the present invention modulates light emitted from a plurality of light sources, a color mixing device that emits a plurality of light beams incident from the plurality of light sources as a single light, and light emitted from the color mixing device. And a light-shielding curtain arranged between the plurality of light sources and the color mixing device for changing the amount of light directed from the light source toward the modulation / projection means.

  In the present invention, the color mixing device emits a plurality of light beams incident from a plurality of light sources as a single light, and the light shielding curtain is disposed between the plurality of light sources and the color mixing device. Therefore, there is an effect that when an image with low luminance is projected on the screen, it is possible to obtain an image with less luminance unevenness and color unevenness.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1>
FIG. 1 is a configuration diagram of a projector according to Embodiment 1 of the invention. As shown in FIG. 1, the light source includes an R light source 1 that generates red light, a G light source 2 that generates green light, and a B light source 3 that generates blue light. Light is emitted toward the device 4. Between each light source and the color mixing device 4, an R light shielding curtain 5 that is a first light shielding curtain that shields light from the R light source 1 and a second light shielding curtain that shields light from the G light source 2. A light shielding curtain 6 and a B light shielding curtain 7 which is a third light shielding curtain for shielding light from the B light source 3 are arranged, and the amount of light emitted from each light source and transmitted through the light shielding curtain by opening and closing the light shielding curtain. Is controlling. The image display device 9, the projection lens 10, the projection lens 11, and the projection lens 12 constitute a modulation / projection means.

  FIG. 2 is a structural cross-sectional view of a light-shielding curtain according to an embodiment of the present invention. As shown in FIG. 2, the light path 14 of light emitted from the light source toward the color mixing device 4 is shielded by the light shielding plate 15. The stay 16 supports the light shielding plate 15, the shaft 18 connects the stay 16 and the pedestal 17, and the actuator 19 drives the end of the stay 16 that faces the light shielding plate 16. By driving the actuator 19, the light shielding plate 15 can be moved to a position where the optical path 14 is blocked, and the amount of light emitted from the light source can be controlled.

  The color mixing device 4 emits a light beam incident from each light source as a single light. The shape of the tube is a hollow polygonal column with a mirror surface on the inner surface, and the light beam incident on the color mixing device 4 is mixed while repeating reflection on the inner surface, and is emitted as uniform white light. The white light beam emitted from the color mixing device 4 passes through the illumination lens 8 and becomes parallel light, and is irradiated onto the video display device 9. The video display device 9 has a reflection-type video display surface, and the incident light beam is brightness-modulated based on the video information and emitted toward the projection lens 10. The light transmitted through the projection lens 10 is transmitted through the projection lens 11 and the projection lens 12 and then projected onto the screen 13 to display an image.

  When displaying an image with low brightness on the screen 13, the light from the light source is not incident on the projection lens 10 by the video display device 9 in order to prevent most of the light from the light source from entering the projection lens 10. It is adjusted by reflecting in the direction. When the light from the light source becomes strong, the amount of light reflected by the video display device 9 in a direction not incident on the projection lens 10 increases, but a part of the reflected light is diffusely reflected without being absorbed by the surrounding structures. The irregularly reflected light becomes unnecessary stray light having no video information and reenters the projection lens 10, the projection lens 11, and the projection lens 12. This stray light increases as the amount of light from the light source increases and is projected onto the screen 13 so as to overlap the original image, leading to deterioration of contrast. As a countermeasure against this problem, the light beams from the R light source 1, the G light source 2, and the B light source 3 are controlled by the R light shielding curtain 5, the G light shielding curtain 6, and the B light shielding curtain 7, and then enter the color mixing device 4. Therefore, the light applied to the video display device 9 is limited, stray light is reduced, and the contrast is improved.

  FIG. 3 is a configuration diagram of a projector in the prior art. In the conventional projector as shown in FIG. 3, the light shielding curtain for the white light emitted from the white light source 20 is installed at the position of the illumination system light shielding curtain 21 and the projection system light shielding curtain 22, for example. For this reason, there were problems as described in the background section. However, in the present invention, as shown in FIG. 1, a light-shielding curtain is installed between the light source and the color mixing device 4. Since the color mixing device 4 has a function to make the light incident from each light source uniform, even if the light emitted from the light source is partially shielded by the light shielding curtain, the cross section of the light beam becomes an irregular shape. The illumination lens 8 can be irradiated with a light beam. Therefore, an image having no partial luminance unevenness and color unevenness with respect to the image projected on the screen 13 can be obtained.

  In the embodiment of the present invention, the light emitted from each of the R light source 1, the G light source 2, and the B light source 3 is controlled independently by each of the R light shielding curtain 5, the G light shielding curtain 6, and the B light shielding curtain 7. can do. As a result, for the image projected on the screen 13, white light is used as a light source by controlling the light shielding curtain so as to reduce the light amount of only unnecessary color light and increase the light amount of necessary color light. It is possible to improve the contrast more effectively than the conventional method that has been controlled.

  Various types of devices can be considered for the light source, but it may be difficult to change the light emission amount of the light source itself from the viewpoint of stability and optical performance. However, according to the embodiment of the present invention, since the amount of light emitted from the light source is controlled by the light-shielding curtain, it is only necessary to keep the light emission amount of the light source itself constant, so that the contrast is improved while maintaining stable optical performance. Can be performed.

  From the above, the amount of light emitted from each light source can be adjusted independently by installing a light shielding curtain between the light source and the color mixing device, and further arranging the light shielding curtain so as to correspond to each light source. Is possible. As a result, there is an effect that when contrast is improved while maintaining stable optical performance and an image with low luminance is projected on the screen, an image with less luminance unevenness and color unevenness can be obtained.

<Embodiment 2>
FIG. 4 is a configuration diagram of a projector according to the second embodiment of the invention. A feature of the second embodiment of the present invention is that a light-shielding curtain is disposed between the light source and the color mixing device, and only one light-shielding curtain is disposed at a location where light beams emitted from the respective light sources converge.

  As shown in FIG. 4, the light source is composed of an R light source 1 that generates red light, a G light source 2 that generates green light, and a B light source 3 that generates blue light. Light is emitted toward the device 4. Between each light source and the color mixing device 4, a light shielding curtain 24 is arranged at a location where the light beam emitted from each light source converges, and light emitted from each light source and transmitted through the light shielding curtain by opening and closing one light shielding curtain 24. The amount of light is controlled. The process until the light emitted from the color mixing device 4 is projected onto the screen 13 is the same as that in the first embodiment.

  From the above, it is possible to further reduce the cost and improve the contrast by installing one light-shielding curtain between the light source and the color mixing device. In addition, there is an effect that when an image with low luminance is projected on the screen, an image with less luminance unevenness and color unevenness can be obtained.

<Embodiment 3>
FIG. 5 is a configuration diagram of a projector according to the third embodiment of the present invention. A feature of Embodiment 3 of the present invention is that a light shielding curtain is disposed between the light source and the color mixing device, and the light shielding curtain is disposed corresponding to each of the plurality of light sources.

  As shown in FIG. 5, the light source is an A light source 25 that generates light of wavelength A, a B light source 26 that generates light of wavelength B, a C light source 27 that generates light of wavelength C, and a light of wavelength D. The generated D light source 28 emits light from each light source toward the color mixing device 4. Thus, by using a plurality of light sources that generate light of an arbitrary wavelength, the color reproduction range of an image projected on the screen 13 can be expanded. Between each light source and the color mixing device 4, the A light shielding curtain 29 that shields the light from the A light source 25, the B light shielding curtain 30 that shields the light from the B light source 26, and the light from the C light source 27 are shielded. The C light shielding curtain 31 and the D light shielding curtain for shielding the light from the D light source 28 are arranged, and the light quantity emitted from each light source and transmitted through the light shielding curtain is controlled by opening and closing each light shielding curtain. ing. The process until the light emitted from the color mixing device 4 is projected onto the screen 13 is the same as that in the first embodiment.

  Based on the above, by arranging a plurality of light-shielding curtains corresponding to a plurality of light sources that generate light of an arbitrary wavelength between the light source and the color mixing device, the light amount can be controlled independently for each light source. It becomes possible to do. Therefore, when an image with low luminance is projected on the screen, it is possible to obtain an image with little luminance unevenness and color unevenness while maintaining color reproducibility.

<Embodiment 4>
FIG. 6 is a configuration diagram of a projector according to Embodiment 4 of the present invention. A feature of Embodiment 4 of the present invention is that a light shielding curtain is disposed between the light source and the color mixing device, and the light shielding curtain is disposed corresponding to any number of light sources among the plurality of light sources. is there.

  As shown in FIG. 6, the light source is an E light source 33 that generates light of wavelength E, an F light source 34 that generates light of wavelength F, a G light source 35 that generates light of wavelength G, and light of wavelength H. The generated H light source 36 emits light from each light source toward the color mixing device 4. Thus, by using a plurality of light sources that generate light of an arbitrary wavelength, the color reproduction range of an image projected on the screen 13 can be expanded. Between each light source and the color mixing device 4, in order to block the light from the E light source 33 and the F light source 34, an EF light shielding curtain 37 is disposed in the optical path of both light sources, and the G light source 35, the H light source 36, and the like. In order to block the light from the light source, a GH shading curtain 38 is installed in the optical path of both light sources. By opening and closing each shading curtain, the amount of light emitted from each light source and transmitted through the shading curtain is controlled. Yes. The process until the light emitted from the color mixing device 4 is projected onto the screen 13 is the same as that in the first embodiment.

  For example, when a laser is used as a light source, light from a plurality of light sources can be projected onto one light shielding curtain by using an optical fiber. A light source equivalent to a light source that emits light of an arbitrary wavelength can be created by combining light from each light source. As described above, the light quantity can be controlled independently by arranging the light-shielding curtain corresponding to each of a plurality of light beams having an arbitrary wavelength.

  From the above, by arranging a plurality of light-shielding curtains corresponding to each arbitrary light source among a plurality of light sources that generate light of an arbitrary wavelength between the light source and the color mixing device, the light quantity can be independently obtained. Can be controlled. Therefore, when an image with low luminance is projected on the screen, it is possible to widen the color reproduction range and obtain an image with less luminance unevenness and color unevenness.

It is a block diagram of the projector by Embodiment 1 of this invention. 1 is a structural cross-sectional view of a light shielding curtain according to an embodiment of the present invention. It is a block diagram of the projector in a prior art. It is a block diagram of the projector by Embodiment 2 of this invention. It is a block diagram of the projector by Embodiment 3 of this invention. It is a block diagram of the projector by Embodiment 4 of this invention.

Explanation of symbols

  1 R light source, 2 G light source, 3 B light source, 4 color mixing device, 5 R light shielding curtain, 6 G light shielding curtain, 7 B light shielding curtain, 8 illumination lens, 9 video display device, 10 projection lens, 11 projection lens, 12 projection Lens, 13 screen, 14 optical path, 15 light shielding plate, 16 stay, 17 pedestal, 18 axis, 19 actuator, 20 white light source, 21 illumination system light shielding curtain, 22 projection system light shielding curtain, 23 condenser lens, 24 light shielding curtain, 25 A light source, 26 B light source, 27 C light source, 28 D light source, 29 A light shielding curtain, 30 B light shielding curtain, 31 C light shielding curtain, 32 D light shielding curtain, 33 E light source, 34 F light source, 35 G light source, 36 H light source 37 EF shading curtain, 38 GH shading curtain.

Claims (5)

Multiple light sources;
A color mixing device that emits a plurality of light beams incident from the plurality of light sources as a single light;
Modulation / projection means for modulating and projecting light emitted from the color mixing device;
A light-shielding curtain that is arranged between the plurality of light sources and the color mixing device, and changes the amount of light directed from the light sources toward the modulation / projection means;
A projector comprising: The plurality of light sources include an R light source, a G light source, and a B light source,
The light-shielding curtain includes a first light-shielding curtain corresponding to the R light source, a second light-shielding curtain corresponding to the G light source, and a third light-shielding curtain corresponding to the B light source. The projector according to claim 1. The plurality of light sources include an R light source, a G light source, and a B light source,
The projector according to claim 1, wherein the light-shielding curtain includes one light-shielding curtain disposed at a location where light beams emitted from the respective light sources converge.   The projector according to claim 1, wherein the light shielding curtain includes a plurality of light shielding curtains provided corresponding to each of the plurality of light sources.   The projector according to claim 1, wherein the light-shielding curtain includes a plurality of light-shielding curtains provided corresponding to an arbitrary number of light sources among the plurality of light sources.

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