JPH11265029A - Projection color picture display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a higher quality picture by a small-sized projection lens. SOLUTION: A projection color picture display 1 is provided with three liquid crystal panels 21, 22 and 23, a optical composite system 31 for compositing light beams of two colors, and two projection lenses 41 and 42. The light beams of three colors of red, green and blue are individually modulated by three liquid crystal panels, and the light beams of two colors after modulated are composited and are projected by one projection lens, and the remaining light beam of one color after modulated is projected by the other projection lens. An optical path length required to put together the light beams of two colors is short, so that the projection lens is closely arranged to the liquid crystal panel, and a large- sized projection lens is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection type image display device for projecting and displaying a color image.

[0002]

2. Description of the Related Art There is a projection type image display apparatus which modulates light according to an image and projects the modulated light onto a screen to display an image. Such a projection type image display device is used to present an image to many people at once, and in recent years,
It is also used for relatively large-screen television receivers. The light is modulated for one image at a time by a spatial modulation element represented by a liquid crystal panel. When a color image is projected and displayed, it is necessary to modulate light according to the color components of the image, for example, three primary colors of red, green and blue.

FIGS. 11 to 14 schematically show the structure of an optical system of a conventional projection type color image display device. The device 5 of FIG. 11 modulates white light W by one liquid crystal panel 101 in which three types of pixels corresponding to respective color components are alternately arranged, so that modulated red light R, green light G, and blue light B Are collectively obtained. The modulated light is projected on the screen by the projection lens 102. The device 6 in FIG. 12 includes three liquid crystal panels 101R, 101G,
The red light R, the green light G, and the blue light B are individually modulated by 101B.
02R, 102G, and 102B are projected and superimposed on the screen.

[0004] The device 7 shown in FIG.
1G, 101RB and two projection lenses 102G, 102RB. One liquid crystal panel 101G modulates light of one color component, for example, green light G. The other liquid crystal panel 101RB is configured by alternately arranging two kinds of pixels corresponding to the light of the remaining two color components, red light R and blue light B, and modulates these lights collectively. The modulated light is projected by the projection lenses 102G and 102RB, respectively, and is superimposed on the screen.

[0005] The device 8 of FIG. 14 includes three liquid crystal panels 101 R, 101 G, and 101 B for modulating light of each color component, a combining optical system, and a projection lens 102. The combining optical system includes two half mirrors 103R and 103G and a total reflection mirror 103B, and combines the three colors of light after modulation. The combined light is guided to the projection lens 102 and projected on the screen.

[0006]

The device 5 shown in FIG.
Although the optical system is very simple, the number of pixels corresponding to each color component is 1/3 of the total number of pixels, so that an image with very high definition cannot be displayed. FIG.
The second device 6 can display a high-definition image, but needs to include three expensive projection lenses.

The device 7 of FIG. 13 is less expensive than the device 6 due to the small number of projection lenses, but the image definition is inferior to the device 6. The device 8 of FIG. 14 can display a high-definition image similarly to the device 6. However, since there is an optical system that combines three colors of light between the liquid crystal panel and the projection lens, the optical path between them becomes long, and if an image is to be displayed with the same brightness, a large projection lens needs to be provided. Occurs. For this reason, despite the fact that there is only one projection lens, it becomes heavy and expensive.

The present invention has been made in consideration of the advantages and disadvantages of these devices, and has as its object to reduce the size of the projection lens of a projection type color image display device without deteriorating the quality of an image to be displayed. And

[0009]

In order to achieve the above object, the present invention modulates three colors of light according to the color components of an image, and projects the modulated light onto a screen to display a color image. A light source unit for supplying first, second and third lights of different colors, and a first space for modulating the first light in accordance with a first color component of the image. A modulator, a second spatial modulator that modulates the second light according to a second color component of the image, and a third space that modulates the third light according to a third color component of the image. A modulation element, and a first element for projecting the first light modulated by the first spatial modulation element.
, A combining optical system that combines the second light modulated by the second spatial modulator and the third light that is modulated by the third spatial modulator, and a combining optical system. A second projection optical system for projecting the second light and the third light; and a first light projected by the first projection optical system and a second light projected by the second projection optical system. And the third light are combined on the screen.

Since the first, second and third lights are individually modulated by the three spatial modulation elements, the light after modulation represents a high-definition image. The first light after modulation is the first light.
Are projected separately from the second and third lights. The modulated second and third lights are combined by the combining optical system and then projected by the second projection lens.
Here, since the combining optical system combines two lights instead of three lights, the optical path length from the second and third spatial modulation elements to the second projection lens does not become too long. Therefore, it is not necessary to provide a very large second projection lens in order to display a bright image. As the first projection lens, the same one as the second projection lens can be used.

It is preferable to use a reflection type as the first, second and third spatial modulation elements. When a reflection-type spatial modulation element is used, the optical paths of the light before modulation and the light after modulation partially overlap, so that the total optical path length is shortened, and the size of the entire device is reduced.

When a reflection type spatial modulation element is used, a polarization beam splitter may be used as the combining optical system. Since the polarizing beam splitter can not only combine light but also separate light, it can be used to generate second and third light by color separation of light. Therefore, if the polarization beam splitter is arranged in a portion where the optical paths of the light before and after the modulation overlap, it is possible to generate the second and third lights and guide them to the second and third modulation elements. That is, the synthetic optical system also serves as a part of the light source unit,
There is no need to dispose members other than the combining optical system between the second and third spatial modulation elements and the second projection lens.
This makes it possible to arrange the second projection lens closer to the second and third spatial modulation elements, and to reduce the size of the second projection lens. Further, the configuration of the light source unit is also simplified.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a projection type color image display device (hereinafter, also simply referred to as a projection type image display device) of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a projection type image display device 1 according to the first embodiment. The projection type image display device 1 is roughly divided into a light source unit 10, a modulation unit 20, a synthesis unit 30, a projection unit 40, and a control unit 50.

The light source unit 10 includes a light source 11 that emits white light W.
And white light W emitted from the light source 11 into red light R, green light G,
And a decomposing optical system 12 for decomposing the light into three colors of blue light B. A decomposition optical system 12 for dividing the white light W into a group including only the blue light B and a group including the red light R and the green light G;
It comprises a rear stage for splitting the red light R and the green light G.

The modulation section 20 includes three spatial modulation elements 21 and 2
2, 23, and a drive unit 24 for driving these. Specifically, reflection type liquid crystal panels are used as the spatial modulation elements 21, 22, and 23, and the liquid crystal panels 21, 22, and 23 respectively have blue light B and red light R
And green light G.

The control unit 50 receives and processes a signal representing an image, for example, a video signal, from the outside, and generates three signals representing a red component, a green component, and a blue component. Then, the driving unit 24 is controlled according to these signals, and the light modulation by the spatial modulation elements 21, 22, and 23 is individually controlled.

The synthesizing unit 30 is composed of a synthesizing optical system 31, and synthesizes the red light R and the green light G modulated by the liquid crystal panels 22 and 23. The synthetic optical system 31 includes the light source unit 30
And splits the undivided red light R and green light G provided from the light source unit 30 and guides them to the spatial light modulators 22 and 23, respectively.

The projection unit 40 includes two projection lenses 41 and 42.
Consisting of The projection lens 41 projects the blue light B modulated by the spatial modulation element 21 onto a screen (not shown).
The projection lens 42 projects the modulated red light R and green light G combined by the combining optical system 31 onto a screen. The projection lenses 41 and 42 are set such that the projected light overlaps on the screen.

FIG. 2 shows the arrangement of the entire optical system of the projection type image display device 1 from the light source unit 10 to the projection unit 40, and shows the configuration and optical paths from the light source 11 of the light source unit 10 to the front stage of the split optical system 12. FIG. The split optical system 12 includes two polarizing beam splitters 13 and 14 and three color filters 15 and 1 that reflect or transmit light according to wavelength.
6 and 17 are provided. The polarization beam splitters 13 and 14 reflect the S-polarized light and transmit the P-polarized light, and each of the prisms 13a is formed by joining two prisms.
And 14a. Note that a polarizing beam splitter formed on the surface of a flat plate may be used.

FIG. 10 shows the characteristics of the color filter. The color filter 15 has the characteristics shown in FIG.
Reflects red light R and transmits shorter wavelength green light G and blue light B. The color filter 16 has the characteristics shown in FIG. 10B, and transmits the blue light B and reflects the red light R and the green light G having longer wavelengths. Color filter 1
7 has the characteristics shown in FIG. 10A, and transmits the green light G and reflects the red light R having a longer wavelength. These color filters 15, 16 and 17 are all formed on the surface of a flat plate.

The polarizing beam splitter 13 is disposed near the light source 11 so as to have a 45 ° inclination with respect to the light emitted from the light source 11, and the polarizing beam splitter 14, color filters 15 and 16
3 are arranged in parallel. The color filter 15 is located at a position receiving the transmitted light of the polarizing beam splitter 13, the color filter 16 is located at a position receiving the reflected light of the polarizing beam splitter 13, and the polarizing beam splitter 14 is receiving the reflected light of the color filters 15 and 16. Is located in the position. The color filter 17 is a color filter 1
6 and the polarizing beam splitter 14, are disposed perpendicular to the reflected light of the color filter 16.

The red light R, the green light G and the blue light B contained in the white light W emitted from the light source 11 are first converted by the polarization beam splitter 13 into P-polarized red light RP and green light G.
The light is divided into transmitted light including P and blue light BP and reflected light including S-polarized red light RS, green light GS and blue light BS. The transmitted light of P polarization enters the color filter 15, and the green light GP and the blue light BP passing through the color filter 15 are discarded. The red light RP reflected by the color filter 15 is incident on the polarization beam splitter 14, passes through it, and is extracted.

The S-polarized reflected light enters the color filter 16, and the blue light BS passing therethrough is extracted. The red light RS and the green light GS reflected by the color filter 16 enter the color filter 17, and the red light RS reflected thereby is discarded. Color filter 17
The green light GS that has passed through is incident on the polarization beam splitter 14 and is reflected, proceeds in the same direction as the P-polarized red light RP, and is extracted.

After all, the white light W
Is divided into a group including only S-polarized blue light BS and a group including P-polarized red light RP and S-polarized green light GS, and both groups are extracted in parallel. The extracted two groups of light are guided to the modulating unit 20 by the synthesizing unit 30 which also functions as the latter stage of the split optical system 12.

The modulator 20, the synthesizer 30, and the projector 40
FIG. 4 schematically shows the configuration and optical path of the first embodiment. FIG. 2 also shows a polarization beam splitter 32 that is a part of the preceding stage of the light source unit 30 and guides the blue light Bs to the modulation unit 20. The synthesizing unit 30 also serving as a subsequent stage of the light source unit 30 includes a synthesizing optical system 31.
And a polarizing beam splitter 33. The polarizing beam splitters 32 and 33 reflect the S-polarized light and transmit the P-polarized light, and are formed on the joining surfaces of the prisms 32a and 33a, which are formed by joining two prisms.

The liquid crystal panel 21 is disposed substantially perpendicular to the optical axis of the projection lens 41, and similarly,
Reference numeral 3 is arranged substantially perpendicular to the optical axis of the projection lens 42. The optical axes of the projection lenses 41 and 42 pass through substantially the centers of the liquid crystal panels 21 and 23, respectively. The polarization beam splitter 32 is disposed between the liquid crystal panel 21 and the projection lens 41 so as to have a 45 ° inclination with respect to the liquid crystal panel. Similarly, the polarizing beam splitter 33 is disposed between the liquid crystal panel 23 and the projection lens 42.
Are arranged so as to have an inclination of 45 ° with respect to. The liquid crystal panel 22 is disposed symmetrically with respect to the liquid crystal panel 23 with respect to the polarization beam splitter 33.

The S-polarized blue light BS enters the polarization beam splitter 32 in parallel with the liquid crystal panel 21, and the P-polarized red light RP and the S-polarized green light GS enter the polarization beam splitter 33. , That is, perpendicular to the liquid crystal panel 22. Although FIG. 4 shows that the P-polarized red light RP and the S-polarized green light GS are incident from the opposite direction to the S-polarized blue light BS, these two groups of light are actually Polarized beam splitters 32 and 33 are taken out in parallel and maintained in a parallel state.
Incident on. FIG. 5A shows the positional relationship between the prism 32a and the liquid crystal panel 21 and the prism 33a and the liquid crystal panels 22 and 23 when viewed from the direction of arrow V in FIG.
(B).

The S-polarized blue light BS incident on the polarizing beam splitter 32 is reflected toward the liquid crystal panel 21. The blue light BS incident on the liquid crystal panel 21 is modulated and reflected by the liquid crystal panel 21.
Change to polarized light. The modulated P-polarized blue light BP passes through the polarization beam splitter 32, enters the projection lens 41, and is projected toward the screen. This light forms an image of the blue component on the screen.

The P-polarized red light RP and the S-polarized green light GS incident on the polarization beam splitter 33 are split by the former being transmitted and the latter being reflected. The P-polarized red light RP transmitted through the polarization beam splitter 33 is
2, the light is modulated and reflected. At this time, the light changes from P-polarized light to S-polarized light. The modulated S-polarized red light RS is reflected by the polarization beam splitter 33 and enters the projection lens 42. The S-polarized green light GS reflected by the polarization beam splitter 33 enters the liquid crystal panel 23 and is modulated and reflected. At this time, the S-polarized green light changes to P-polarized light. The modulated P-polarized green light GP passes through the polarization beam splitter 33 and enters the projection lens 42.

The modulated red light RS and green light GP are combined in this manner, and are projected toward the screen by the projection lens 42. These lights simultaneously form an image of the red component and an image of the green component on the screen, and overlap with the image of the blue component to form a color image.

The prisms 32a, 33a on which the polarizing beam splitters 32, 33 are formed, the liquid crystal panels 21, 22,
The projection lenses 41 and 42 have the same size and the same performance. The liquid crystal panel 21 substantially contacts the prism 32a, and the liquid crystal panels 22 and 23 also substantially contact the prism 33a. Therefore, prism 3
The vertical and horizontal sizes of 2a and 33a in FIG. 4 are set to be the same as or slightly larger than the sizes of the liquid crystal panels 21 and 23.

The projection lenses 41 and 42 are arranged close to the prisms 32a and 33a, respectively. By setting the optical system in this way, the liquid crystal panels 21, 22, 23
Since the optical path length from the light source to the projection lenses 41 and 42 is short, a bright image can be displayed even if the projection lenses 41 and 42 are not provided with lenses having a very large diameter.

The projection type image display device 2 according to the second embodiment will be described. The projection-type image display device 1 of the first embodiment modulates the S-polarized blue light BS, but the projection-type image display device 2 of the present embodiment modulates the P-polarized blue light B
Modulate P. Most of the configuration of the projection type image display device 2 is the same as that of the projection type image display device 1, and the same members are denoted by the same reference numerals and overlapping description will be omitted.

FIG. 6 shows the arrangement of the entire optical system of the projection type image display device 2, and FIG. 7 shows the structure and optical path of the light source unit 10. The light source unit 10 is provided with a half-wave plate 18, and the S-polarized blue light BS extracted from the white light W by the polarization beam splitter 13 and the color filter 16.
Is converted into P-polarized light by the λλ wave plate 18.

The modulator 20, the synthesizer 30, and the projector 40
FIG. 8 schematically shows the configuration and the optical path of the first embodiment. P-polarized blue light B
The liquid crystal panel 21 that modulates P is used for the projection-type image display device 1.
In contrast to this, it is arranged at a position to receive the transmitted light of the polarization beam splitter 32.

The blue light BP passes through the polarization beam splitter 32 that reflects S-polarized light and transmits P-polarized light, and enters the liquid crystal panel 21. The blue light BP incident on the liquid crystal panel 21 is modulated and reflected. At this time, the blue light BP changes from P-polarized light to S-polarized light. The modulated S-polarized blue light BS enters the polarization beam splitter 32, and thereby the projection lens 4
The light is reflected toward 1 and projected by the projection lens 41. This blue light BS is projected on the screen by the projection lens 42.
And a red light RS and a green light GP projected by the light source and form a color image.

The projection type image display device 3 according to the third embodiment will be described. FIG. 9 shows a configuration and an optical path of an optical system of the projection type image display device 3. The light source unit of the projection type image display device 3 includes a light source 61 that emits white light W, two color filters 62 and 63 that reflect or transmit light according to the wavelength, and three total reflection mirrors 64, 65 and 66. . The color filter 62 has the characteristics shown in FIG.
Reflects red light R and transmits shorter wavelength green light G and blue light B. The color filter 63 has the characteristics shown in FIG. 10B, and transmits the blue light B and reflects the green light G having a longer wavelength.

The modulating section has a transmissive liquid crystal panel as the spatial modulating elements 71, 72 and 73. The liquid crystal panels 71, 72, and 73 modulate the red light R, the blue light B, and the green light G, respectively, include a polarizing plate on the incident side, and are controlled by a control unit (not shown) via a driving unit. You.

The combining section comprises a color filter 82 for reflecting or transmitting light according to the wavelength. Color filter 8
Numeral 2 is formed on a joint surface of a prism 82a formed by joining two prisms, and has a characteristic shown in FIG.
Reflects blue light B and transmits longer wavelength green light G. The liquid crystal panels 72 and 73 are disposed substantially in contact with adjacent side surfaces of the prism 82a. The prism 81 having the same size as the prism 82a is used to make the optical path length uniform.
a, and the liquid crystal panel 71 has a prism 81a.
Are disposed substantially in contact with.

The projection unit is composed of two projection lenses 91 and 92, and the light projected by each of them is superimposed on a screen. Each of the projection lenses 91 and 92 includes a prism 81
a and 82a.

The red light R, the green light G and the blue light B included in the white light W emitted from the light source 11 are first reflected by the color filter 62 into the reflected light including only the red light R and the green light G and the blue light B. And transmitted light containing The red light R is reflected by the total reflection mirror 64 and
1 and is modulated while passing through the liquid crystal panel 71. The modulated red light R passes through the prism 81a, enters the projection lens 91, and is projected toward the screen.

The green light G and the blue light B transmitted through the color filter 62 are split by the color filter 63.
The blue light B transmitted through the color filter 63 is reflected by the total reflection mirror 65, enters the liquid crystal panel 72, and is modulated while passing through the liquid crystal panel 72. The modulated blue light B is reflected by the color filter 82 and enters the projection lens 92.

The green light G reflected by the color filter 63 is reflected by the total reflection mirror 66, enters the liquid crystal panel 73, and is modulated while passing through the liquid crystal panel 73. The modulated green light G passes through the color filter 82 and enters the projection lens 92. In this way, the green light G and the blue light B are combined by the color filter 82, and are projected toward the screen by the projection lens 92. These lights overlap the blue light on the screen to form a color image.

As described above, the projection type color image display device of the present invention modulates three colors of light individually by the three spatial modulation elements, so that a high-definition image can be displayed. In addition, since the number of projection lenses is smaller than the number of spatial modulation elements and the configuration is provided with two projection lenses, there is no need to combine all three colors of light. It is possible to arrange it close to. As a result, a relatively small diameter projection lens can be used, and miniaturization of the projection lens in both number and size has been achieved. Therefore, the projection type color image display device of the present invention has high performance, small size, light weight and low cost.

It is to be noted that which of the three colors of light is combined with which is optional, and may be determined in consideration of the characteristics of an optical element required for the decomposition and combination of light and the visibility of light. . Further, it is optional to employ either the reflection type or the transmission type spatial modulation element, and there is no difference in the distance from the spatial modulation element to the projection lens in both the reflection type and the transmission type.
However, it is preferable to use a reflection-type spatial modulation element because the optical paths of the light before modulation and the light after modulation partially overlap, thereby making it possible to make the entire device smaller.

[0046]

According to the projection type color image display device of the first aspect, since the three colors of light are individually modulated by the three spatial modulation elements, a high-definition color image can be displayed. In addition, since two lights are combined instead of three lights, the optical path length required for the combination is short, and the projection lens can be arranged close to the spatial light modulator. Images can be displayed. Therefore, the device is small, lightweight, and inexpensive even though it is a device capable of displaying high-quality images.

The projection type color image display device according to the second aspect can be made particularly small, and is suitable as a home display device such as a television receiver.

In the projection type color display device according to the third aspect, since the combining optical system can be used for both generation of light of two colors and supply to the spatial light modulator, the projection lens is arranged closer to the spatial light modulator. It is possible to further reduce the size of the projection lens. Moreover, 2
Since it is not necessary to separately provide a means for generating color light, the configuration of the entire apparatus is simplified.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a projection-type image display device according to a first embodiment.

FIG. 2 is a diagram illustrating an arrangement of the entire optical system of the projection type image display device according to the first embodiment.

FIG. 3 is a diagram illustrating a configuration and an optical path of a light source unit of the projection-type image display device according to the first embodiment.

FIG. 4 is a diagram illustrating a configuration and an optical path of a modulation unit, a synthesis unit, and a projection unit of the projection-type image display device according to the first embodiment.

FIG. 5 is a diagram showing a positional relationship between a modulation unit and the periphery of the modulation unit of the projection type image display device according to the first embodiment.

FIG. 6 is a diagram illustrating an arrangement of an entire optical system of a projection-type image display device according to a second embodiment.

FIG. 7 is a diagram illustrating a configuration and an optical path of a light source unit of a projection-type image display device according to a second embodiment.

FIG. 8 is a diagram illustrating a configuration and an optical path of a modulation unit, a synthesis unit, and a projection unit of the projection-type image display device according to the second embodiment.

FIG. 9 is a diagram illustrating a configuration and an optical path of an optical system of a projection-type image display device according to a third embodiment.

FIG. 10 is a graph showing wavelength dependence of reflection and transmission of a color filter.

FIG. 11 is a diagram showing a configuration of an optical system of a conventional projection type image display device.

FIG. 12 is a diagram showing a configuration of an optical system of another conventional projection image display device.

FIG. 13 is a diagram showing a configuration of an optical system of still another conventional projection type image display device.

FIG. 14 is a diagram showing a configuration of an optical system of still another conventional projection image display device.

[Explanation of symbols]

 1, 2, 3 Projection type color image display device 10 Light source unit 11 Light source 12 Resolving optical system 13, 14 Polarizing beam splitter 13a, 14a Prism 15, 16, 17 Color filter 18 1 / 2λ wave plate 20 Modulating unit 21, 22, Reference Signs List 23 reflective liquid crystal panel (spatial modulation element) 24 drive unit 30 combining unit 31 combining optical system 32, 33 polarizing beam splitter 32a, 33a prism 40 projecting unit 41, 42 projection lens (projection optical system) 50 control unit 61 light source 62, 63 Color filter 64, 65, 66 Total reflection mirror 71, 72, 73 Transmission liquid crystal panel (spatial modulation element) 82 Color filter 81a, 82a Prism 91, 92 Projection lens (projection optical system)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03B 33/12 G03B 33/12

Claims (3)

[Claims] 1. A projection type color image display device which modulates three colors of light in accordance with the color components of an image and projects the modulated light onto a screen to display a color image. A light source unit that supplies second and third light; a first spatial modulation element that modulates the first light according to a first color component of an image; and a light source unit that modulates the first light according to a second color component of the image. A second spatial light modulator that modulates the second light, a third spatial light modulator that modulates the third light according to a third color component of the image, and a light beam that is modulated by the first spatial light modulator. A first projection optical system for projecting the generated first light, the second light modulated by the second spatial modulation element, and the third light modulated by the third spatial modulation element. A combining optical system for combining light, and the second light combined by the combining optical system A second projection optical system for projecting a third light, wherein the first light projected by the first projection optical system and the second light projected by the second projection optical system And a color image is displayed by synthesizing the third light on a screen. 2. The projection type color image display device according to claim 1, wherein said first, second and third spatial modulation elements are of a reflection type. 3. The projection type color image display device according to claim 2, wherein said combining optical system is a polarization beam splitter.