JP2001042461A - Back projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain miniaturization by reducing the increase of height due to the reduction of thickness by arranging an optical unit on the side lower than a reflection mirror arranged above the reflection on the side mirror arranged at the lowest position and below the reflection mirror arranged at the highest position. SOLUTION: This device is provided with the optical unit 2 to generate video light, a screen 7 on which a picture is formed by projecting the video light, first to fourth mirrors 3-6 to lead the video light emitted by the optical unit 2 to the screen 7 and a housing 1 to integrally hold them. The first reflection mirror 3 is formed into the concave shape of an aspherical surface, and is arranged at the lowest part of the housing 1, and the second reflection mirror 4 is formed into the convex shape of the aspherical surface, and is arranged at a position at which it is opposed to the first reflection mirror 3 inside the housing 1. The third reflection mirror 5 is formed into the convex shape of the aspherical similar to that of the second reflection mirror 4, and is arranged between the first reflection mirror 3 and the screen 7 inside the housing 1, and the fourth reflection mirror 6 is formed into a flat plate-like shape, and is arranged above the second reflection mirror 4 inside the housing 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection display device for projecting image light from the back of a screen and observing an image from the front of the screen.

[0002]

2. Description of the Related Art FIG. 5A shows an example of a configuration of a general rear projection display device.

As shown in FIG. 1, this type of rear-projection display device includes a housing 101, an optical unit 102 disposed in the housing 101, and a light emitting opening of the optical unit 102 opposed to the light emitting opening. Projection lens 103 and housing 101
A reflection mirror 106 disposed on the back of
And a transmissive diffusion screen 107 disposed on the front surface of the display.

[0004] The optical unit 102 performs modulation based on image information, and the image light is magnified and projected on a reflection mirror 106 via an optical lens 103. Reflection mirror 1
The image light enlarged and projected at 06 is applied to the back side of the screen 107 to form an image. The image formed on the screen 107 is observed from the front side of the screen 107.

In recent years, in order to reduce the thickness of the rear projection display device having such a configuration, a plurality of curved reflecting mirrors 203, 204, and 20 as shown in FIG.
An apparatus using a mirror 5 and a flat reflecting mirror 206 has been proposed. And in such a rear projection type display,
The image light emitted from the optical unit 102 is reflected by the reflection mirrors 203 and 20 arranged upward from near the bottom surface.
4, 205, and 206 sequentially reflect and irradiate the screen 107, thereby forming an image.

[0006]

However, in such a conventional rear projection display device, the image light emitted from the optical unit 102 disposed on the bottom face is reflected by all the reflection mirrors 203, 204, 205, 206. In this case, since the light is reflected upward from below, there is a problem that the height increases as the housing 201 is made thinner.

Accordingly, the present invention has been made in view of such a problem, and an object of the present invention is to reduce the size of a rear projection display device by reducing the increase in height associated with the reduction in thickness. And

[0008]

SUMMARY OF THE INVENTION The present invention provides an optical unit for optically modulating light emitted from a light source based on image information and outputting the same, and the image light output from the optical unit on the back surface of a screen. A rear projection display device for observing an image from the front side of the screen, wherein the projection unit includes a plurality of reflection mirrors, and is disposed at a lowest position among the plurality of reflection mirrors. The optical unit is arranged above the reflection mirror and below the reflection mirror arranged at the highest position among the plurality of reflection mirrors.

With such a configuration, the optical unit is disposed in the gap between the plurality of reflection mirrors constituting the projection means, so that the height of the apparatus is reduced.

The present invention also provides an optical unit for optically modulating and outputting light emitted from a light source based on image information, and enlarging and projecting the image light output from the optical unit on the back surface of a screen. A rear projection display device for observing an image from the front side of the screen, wherein the projection unit includes a plurality of reflection mirrors, and the optical unit is first irradiated with light emitted from the optical unit among the reflection mirrors. The reflection mirror is disposed obliquely upward with respect to the reflection mirror.

[0011] With this configuration, the light emitted from the optical unit is radiated to the first reflecting mirror from obliquely above, and then is radiated to the screen via several reflecting mirrors.

Further, the optical unit is characterized in that the optical unit is arranged on the side of a light beam from a reflection mirror located at a lower position to the optical unit toward a reflection mirror located at a higher position.

With such a configuration, the light beam traveling from the reflection mirror located at a lower position with respect to the optical unit to the reflection mirror located at a higher position passes through a position shifted laterally with respect to the optical unit. Become.

More specifically, the projection means includes a plurality of aspherical reflecting mirrors serving as lenses.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rear projection type display according to an embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, FIG. 1 is a sectional view (a) and a partially cutaway front view (b) showing a schematic configuration of a rear projection display device, and FIG. 2 is an optical view of the rear projection display device of FIG. FIG. 3 is an enlarged cross-sectional view illustrating a configuration of a screen in the rear projection display device of FIG. 1.

As shown in FIG. 1, the rear projection display device according to the present embodiment includes an optical unit 2 for generating image light, a screen 7 on which the image light is projected to form an image, and an optical unit. 1 to 4 are provided with first to fourth mirrors 3 to 6 for guiding image light emitted from 2 to a screen 7 and a housing 1 for integrally holding these.

The first reflecting mirror 3 has an aspherical concave shape and is arranged at the lowermost part of the housing 1. The second reflection mirror 4 has an aspherical convex shape, and is arranged in the housing 1 at a position facing the first reflection mirror 3. The third reflection mirror 5 has an aspherical convex shape like the second reflection mirror 4, and is arranged between the first reflection mirror 3 and the screen 7 in the housing 1. The fourth reflection mirror 6 has a flat plate shape, and is disposed above the second reflection mirror 4 in the housing 1.

The optical unit 2 is disposed between the second reflection mirror 4 and the fourth reflection mirror 6 and shifted to the left with respect to the first reflection mirror 3 in the drawing.

As shown in FIG. 2, the optical unit 2 is of a so-called three-plate type, and selectively reflects a metal halide lamp 21 having a reflector 21a and light in a wavelength range corresponding to red. A first dichroic mirror 22 that transmits light in a wavelength range; a second dichroic mirror 23 that selectively reflects light in a wavelength range corresponding to green and transmits light in other wavelength ranges; 1
And first to third liquid crystal panels 27r, 27g, and 27b that optically modulate each color light separated by the second dichroic mirrors 22 and 23 based on video information;
These first to third liquid crystal panels 27r, 27g, 2
And a dichroic prism 28 for synthesizing each color light modulated by 7b.

Then, the white light emitted from the metal halide lamp 21 is reflected by the reflector 21a,
After the ultraviolet and infrared rays are removed by a V / IR filter (not shown), the light is applied to the first dichroic mirror 22 at an angle of 45 degrees.

The first dichroic mirror 22 selectively reflects red component light (hereinafter referred to as red light) of the irradiated white light. The reflected red light is reflected by the first reflection mirror 24, and then is applied to the first liquid crystal panel 27r. The red light is subjected to optical modulation according to the red image information by the first liquid crystal panel 27r, and then enters the color synthesizing dichroic prism.

On the other hand, the light of the remaining color components transmitted through the first dichroic mirror 22 is applied to the second dichroic mirror 23 at an angle of 45 degrees.

The second dichroic mirror 23 selectively reflects green component light (hereinafter referred to as green light) of the irradiated color light, and irradiates the second liquid crystal panel 27g. This green light is emitted from the second liquid crystal panel 27g.
After being subjected to optical modulation according to green image information, the light enters a dichroic prism 28 for color synthesis.

The blue component light (hereinafter, referred to as blue light) transmitted through the second dichroic mirror 23 is sequentially reflected by the second and third mirrors 25 and 26,
The light is emitted to the third liquid crystal panel 27b. In the third liquid crystal panel 27b, after being subjected to optical modulation according to blue image information, the light is incident on a dichroic prism 28 for color synthesis.

The respective color lights incident on the dichroic prism 28 are color-combined and emitted as color image light.

As shown in FIG. 1, the image light emitted from the dichroic prism 28 is emitted obliquely downward and to the right, and irradiates the first reflection mirror 3 disposed at the bottom in the housing 1. You. The image light applied to the first reflecting mirror 3 is sequentially reflected by the second to fourth reflecting mirrors 6 and applied to the back side of the screen 7 arranged in the front opening of the housing 1. , An image is formed. At this time, each of the first to third reflecting mirrors 3 to 5 corrects aberrations such as astigmatism, coma, and distortion of the image light by a lens action according to the shape, and enlarges and projects the image light. ing.

As shown in FIG. 3, the screen 7 includes a Fresnel lens screen 71 made of an acrylic resin and a lenticular lens screen 72.
The image light reflected by the mirror 6 is applied to the back surface of the Fresnel lens screen 71, the image light transmitted through the Fresnel lens screen 71 is applied to the lenticular lens screen 72, and an image is formed by the diffusion action.

As described above, according to the present embodiment, the housing 1
By disposing the optical unit 2 between the lowermost first reflecting mirror 3 and the uppermost fourth reflecting mirror 6 among the plurality of reflecting mirrors disposed therein, the first reflecting mirror Since the space between the third and fourth reflection mirrors 6 can be effectively used, the increase in the height direction due to the reduction in thickness can be reduced, and the size of the device can be reduced.

Further, the light beam traveling from the second reflecting mirror 4 located at a lower position with respect to the optical unit 2 to the third reflecting mirror 5 located at a higher position with respect to the optical unit 2 is shifted obliquely to the side. With this arrangement, the height difference between the two reflecting mirrors 4 and 5 can be made smaller, and the size of the device can be further reduced.

In the present embodiment, the projection means is constituted by a combination of three aspherical reflecting mirrors 3 to 5 and one flat reflecting mirror 6, but the present invention is not limited to this. Instead, a combination of various reflection mirrors or a combination of a lens and a reflection mirror may be used.

Further, in the present embodiment, the optical unit 2 is arranged to be shifted leftward with respect to the light beam traveling from the second reflection mirror 4 to the third reflection mirror 5 in FIG. 1B. It may be arranged shifted to the right, or may be arranged without being shifted to the left or right as shown in FIGS. However, when the optical unit 2 is arranged as shown in FIGS. 4A and 4B, compared with the case where the optical unit 2 is arranged as shown in FIG. In order to dispose the optical unit 2 without passing the light beam toward the reflection mirror 5, the height difference between the second reflection mirror 4 and the third reflection mirror 5 needs to be increased.

[0033]

According to the present invention, by arranging the optical unit between the lowermost reflecting mirror and the uppermost reflecting mirror among the plurality of reflecting mirrors disposed in the housing, both reflections are achieved. Since the space between the mirrors can be effectively used, an increase in the height direction due to the reduction in thickness can be reduced, and the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a schematic configuration of a rear projection display device according to an embodiment of the present invention, and FIG.

FIG. 2 is a configuration showing a schematic configuration of an optical unit in the rear projection display device of FIG. 1;

FIG. 3 is a partially enlarged sectional view showing a schematic configuration of a screen in the rear projection display device of FIG.

FIG. 4 is a sectional view (a) and a partially cutaway front view (b) showing a schematic configuration of a rear projection display device according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a conventional rear projection display device.

[Explanation of symbols]

 1: housing 2: optical unit 3: first reflecting mirror 4: second reflecting mirror 5: third reflecting mirror 6: fourth reflecting mirror 7: screen 71: Fresnel lens screen 72: lenticular lens screen

Claims (4)

[Claims] 1. An optical unit for optically modulating light emitted from a light source based on image information and outputting the same, and projection means for enlarging and projecting the image light output from the optical unit onto the back surface of a screen. In the rear projection display device for observing an image from the front side of the screen, the projection means includes a plurality of reflection mirrors, above the reflection mirror arranged at the lowest position among the plurality of reflection mirrors, and A rear projection display device, wherein the optical unit is disposed below a reflection mirror disposed at the highest position among the plurality of reflection mirrors. 2. An optical unit for optically modulating and outputting light emitted from a light source based on image information, and a projection unit for enlarging and projecting the image light output from the optical unit onto the back surface of a screen. In the rear projection display device for observing an image from the front side of the screen, the projection unit includes a plurality of reflection mirrors, and the optical unit is configured to first emit light emitted from the optical unit among the reflection mirrors. A rear projection display device, which is disposed obliquely upward with respect to a reflection mirror to be used. 3. The optical unit according to claim 1, wherein the optical unit is disposed laterally with respect to a light beam traveling from a reflection mirror located at a lower position to the optical unit toward a reflection mirror located at a higher position. 2. The rear projection display device according to 2. 4. The apparatus according to claim 1, wherein said projection means includes a plurality of aspherical reflecting mirrors serving as a lens.
4. The rear projection display device according to any one of items 1 to 3.