JPH04113309A - Projection type color display device - Google Patents

Abstract

PURPOSE:To obtain a projection type color display device having a color separation system which can separate white light from a light source by colors without generating any color irregularity by providing the color separation system which separates the white light into the primary colors R, G, and B, a light valve which controls the transmission of light beams of the primary colors, and a color composition system which composes the light of the transmitted light beams of the primary colors. CONSTITUTION:The white light from the light source is made incident on a polarization beam splitter and the white light projected from the polarization beam splitter is made incident on a 1/4-wavelength plate and a 0 deg.-incidence dichroic filter which transmits the light beams of R, G, and B respectively, thereby separating the light beams of R, G, and B respectively. The separated light beams of R and B are made incident on condenser lenses 41R and 41B through two total reflecting mirrors 27 and the light beam of G is made incident directly on a condenser lens 41G. The light beams of R, G, and B which are transmitted through the lenses 41R, 41G, and 41B are made incident on light valves 40R, 40G, and 40B respectively. Those valves control the transmission of the light beams of R, G, and B. The light beams of R, G, and B which are made into monochromatic images by passing through the valves are made incident on a cube type dichroic prism 30 to perform color composition and the composite image is projected from a surface 34 and displayed through a projection lens 42.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention separates white light emitted from a light source into three primary colors, transmits each color through a light valve, and then synthesizes the transmitted light. The present invention relates to a projection type color display device that performs display.

(Prior art) Conventionally, white light emitted from a light source is divided into red, green,
A color separation system that separates light into three primary colors of blue (hereinafter abbreviated as R, G, and B, respectively), a light valve that controls transmission of the light separated by the color separation system, and a light valve that controls the transmission of the light separated by the color separation system. Projection type color display devices are known that have a color synthesis system that performs recombination. As an example of a color separation system in a conventional projection type color display device, one using a dichroic mirror with an incident angle of 45° is shown in FIGS. Figure 7 shows what happened.

In FIG. 6(a), the white light emitted from the lamp 51 and the white light reflected by the reflector 52 are
The light enters a 45° incident R reflection dichroic mirror 53 that reflects the R light incident at 45°, and the R component is separated as reflected light. Next, the B component is separated by a 45° incident B reflection tichroic mirror 54, and finally the G component is reflected by a total reflection mirror 55.

In the color separation system shown in FIG. 6(b), both dichroic mirrors 53 and 54 are crossed in an X-shape, and the crossing portions are joined with an optical adhesive.

A cube type tichroic prism 56 is used in the color separation system shown in FIG. The cube-type tichroic prism 56 is made up of four 45° right-angle prisms bonded together as shown in the figure, and the bonded surface has a film 59 that reflects R at an incident angle of 45° and a film 59 that reflects R at an incident angle of 45°. A film 58 that reflects B is also formed. Therefore, the white light incident on this prism 56 has B reflected by the reflective film 58, R reflected by the reflective film 59, and
8 and G passing through 59, respectively. 7th
The cube-shaped Gikuroinoku Prizuku shown in the figure is shown in Figure 6 (a
) and (b), the dichroic mirrors 54 and 53 are more expensive due to the manufacturing method, and are therefore used only when miniaturization of the entire device is required.

As mentioned above, in the conventional color separation system, a dichroic ink mirror 53, 54 or a dichroic prism 56 is used.
Due to the 45° incident guichroic film provided in
For example, among light incident at an incident angle of 45°, only light of a specific wavelength is reflected to perform color separation.

(Problem to be Solved by the Invention) In each of the above-mentioned conventional examples, color separation of white light is performed using a tichroic film with an incident angle of 45°.
In the tichroic film, if the angle of incidence deviates from 45°, its spectral characteristics will change drastically. That is, as shown in FIG. 8, when light rays a and bS c having the same spectrum and different angles of incidence are incident on the dichroic mirror 57 of 45° incidence, the reflected light +
The spectra of bC' will differ from each other. Such a dichroic mirror 57 with 45° incidence
Due to this characteristic, when non-parallel light is color-separated, color unevenness occurs in the reflected light (including transmitted light). Moreover, especially in the conventional examples shown in FIGS. 6(b) and 7, a part of the incident light is scattered at the intersection of the dichroic mirrors 53 and 54 or at the junction formed at the center of the dichroic prism 56. Therefore, layer color unevenness is likely to occur. Such color unevenness causes color unevenness in the image that is ultimately projected onto the screen via the color composition system, resulting in a problem in that the display quality of the image is impaired.

The present invention solves these problems, and an object of the present invention is to provide a projection type color display device having a color separation system capable of color-separating white light from a light source without causing color unevenness. That's true.

(Means for Solving the Problems) The projection type color display device of the present invention includes a color separation system that separates white light emitted from a light source into light of three primary colors, RSG and B; A projection type color display device comprising: a light valve that controls the transmission of the three primary color lights, and a color synthesis system that synthesizes the three primary color lights transmitted through the light valve, the color separation system a polarizing beam splitter that separates the white light incident from the light source into an S-polarized component and a P-polarized component and outputs the same; and a polarizing beam splitter that faces three output surfaces other than the incident surface of the polarized beam splitter a quarter-wave plate provided with its optical axis tilted at 45 degrees with respect to the polarization axis direction, and each of the quarter-wave plates is disposed on the opposite side of the polarizing beam sifter,
Equipped with a 0° incident R transmitting dichroic ink filter, a 0° incident R transmitting dichroic filter, and a 08 incident B transmitting dichroic filter that transmit only R, G, and B light among incident light having an incident angle of Oo. = 6, thereby achieving the above objective.

(Function) In the projection type color display device of the present invention, the white light emitted from the light source is made incident on the polarizing beam splitter, and the white light emitted from the polarizing beam splitter is sent to the quarter-wave plate, R, The R, G, and B lights are sequentially incident on a dichroic filter with θ° incidence that transmits each of the G and B lights.
The light is separated sequentially.

(Example) Examples of the present invention will be described below.

FIG. 1 is a schematic diagram of a first embodiment of a projection type color display device according to the present invention, and FIG. 2 is a schematic diagram showing a color separation system of the display device of FIG. As shown in FIG. 1, the projection type color display device of this embodiment includes a color separation system 1 that separates white light emitted from a light source 14 into light of three primary colors, R, G, and B; Ride valves 40R, 40G, and 40B each control the transmission of the three primary color lights separated in system 1.
and 3 transmitted through light valves 40R, 40G, and 40B.
It is equipped with a color synthesis system 2 that synthesizes primary color light. The color separation system 1 and the color synthesis system 2 are arranged in series on the optical axis.

The color separation system 1 includes a polarization beam splitter 1) that separates the white light incident from the light source 14 into an S-polarized component and a P-polarized component and outputs the separated white light, and a vine 20. The polarizing beam splitter 20 is formed into a cube shape by bonding two right-angle prisms 21 together, and the white light incident from the surface 22a is directed to the surface 22a.
It is emitted from R and 22G. Polarizing beam splitter 20
1/4 wavelength plates 23R, 23G, 23 facing the three exit surfaces 22R, 22G, 22B other than the entrance surface of
B is provided. Quarter wavelength plate 23R123G,
The optical axis of 23B is set at an angle of 456 with respect to the polarization axis direction of the polarization beam splitter 20. each 4
Of the light incident at Oo, the R and G portions of the half-wavelength plates 23R, 23G, and 23B, respectively, are incident on the opposite side of the polarization beam splitter.

A 06 incident R transmitting dichroic filter 24 and a 06 incident G transmitting dichroic filter 26 that transmit only the B light are provided. Dichroi,.

Total reflection mirrors 27 and 27 are provided on the opposite sides of the optical filters 24 and 26 from the polarizing beam splitter 20.

The light source 14 has a lamp 10 and a reflector 11. A heat absorption filter 12 is provided between the light source 14 and the polarizing beam splitter 20 to remove infrared rays.

Color synthesis system 2 is a cube-shaped dichroic prism 30
and a projection lens 42. The cube-shaped dichroic prism 30 has a cubic shape, and has surfaces 31 to 33.
The light incident thereon is emitted from the surface 34. three surfaces 31 on which light enters the cube-shaped dichroic prism 30;
A light valve 40R consisting of a liquid crystal panel faces 32 and 33.

40G, 40B, and condenser lenses 41R, 41G.

41B are arranged respectively. The display mode of the liquid crystal panel is a two-layer STN using polarizing plates.

A projection lens 42 is arranged facing the surface 34 of the cube-shaped dichroic prism 30, and a screen 43 is provided on the opposite side of the projection lens 42 from the prism 30. Total reflection mirrors 27 and 27 are provided on the sides of the condensing lenses 41R and 41B opposite to the prism 30, respectively.

The white light emitted from the lamp 10 passes through a heat absorption filter 12 either directly or after being reflected by a reflector 11.
Infrared rays are removed. As a result, white light that does not contain infrared rays enters the polarized beam splitter 20.

Figure 3. and FIG. 4 are diagrams for explaining the principle of color separation of the color separation system 1 shown in FIG. 2 by dividing the incident white light into an S-polarized light component and a P-polarized light component.

The principle of color separation of the S-polarized component of incident light will be explained with reference to FIG. The S-polarized light component 13s of the white light from the lamp 10 enters the polarizing beam splitter 20, is reflected at a right angle by the surface 20a, and is reflected by the quarter-wave plate 23R facing the surface 22H.
incident on the When this linearly polarized light passes through the quarter-wave plate 23R, it becomes circularly polarized light and enters the 0° incident R transmission polarization filter 24. Of the light incident on the R-transmitting dichroic filter 24, the R component is transmitted through the R-transmitting dichroic filter 24. As a result, only the R component of the white light is extracted. On the other hand, the remaining G and B components are R
It is reflected by the transmission tichroic filter 24 and passes through the quarter-wave plate 23 again to become P-polarized linearly polarized light 13.
p and enters the polarized beam splinter 20. The linearly polarized light 13p is transmitted through the polarized beam splinter 20 and
2B and passes through a quarter wavelength plate 23B.

The light transmitted through the quarter wavelength plate 23B becomes circularly polarized light and reaches the 0° incident B transmission Teichroitsch filter 26.

Of the light incident on this B-transmission dichroic filter 26, the B component is transmitted through the B-transmission dichroic filter 26 and extracted. B transmission tie chroic filter 26
The G component that cannot pass is reflected by the B-transmission dichroic filter 26, passes through the quarter-wave plate 23B again, becomes S-polarized light 13s, enters the polarization beam splitter 20, and is reflected at right angles by the surface 20a. be done. This light having only the G component is emitted from the surface 22G and is transmitted to the quarter wavelength plate 2.
3G, passes through a 0° incident G transmission dichroic filter 25, and is taken out.

The principle of color separation of the P-polarized component of white light incident on the color separation system 1 will be explained with reference to FIG. The linearly polarized light 13p of the P polarized light component of the white light from the lamp 10 enters the polarizing beam splitter 20, passes through the surface 20a and the surface 22G, and further passes through the quarter wavelength plate 23G, becoming circularly polarized light. and reaches the 0° incident transmission dichroic filter 25. Of the light incident on the G-transmitting dichroic filter 25, the G component is extracted as light transmitted through the G-transmitting dichroic filter 25. On the other hand, the remaining RSB components are reflected by the G transmission dichroic filter 25 and are again reflected by the quarter e long plate 2.
3G, becomes S-polarized linearly polarized light 13s, and enters the polarization beam splitter 20 again. The linearly polarized light 13s entering the polarizing beam splitter 20 from the surface 22G is reflected at a right angle by the surface 20a and exits from the surface 22B.

The light emitted from the surface 22B passes through the quarter-wave plate 23B, becomes circularly polarized light, and reaches the 0° incident B transmission Teichroitz filter 26. Of the light incident on this B-transmitting tychroic filter 26, the B component is transmitted as transmitted light.
The R component is extracted from the transmission dichroic filter 26 and reflected by the B transmission dichroic filter 26.

This R-component light passes through the quarter-wave plate 23B, becomes P-polarized light 13p again, enters the polarization beam splitter 20, and is transmitted through the surface 20a. This light is emitted from the surface 22R, passes through the quarter wavelength plate 23R, and further passes through the R transmission dichroic filter 24 and is extracted.

As shown in FIG. 1, the separated R and B lights enter the condenser lenses 41R and 41B via two total reflection mirrors 27, respectively, and the G light enters the condenser lens 41G directly. . The R, G, and B lights that have passed through the condenser lenses 4 R141G and 41B are transmitted through the light valves 40R and 40R, respectively.
Input to 40G and 40B. light bulb 40R140
In G and 4OB, transmission of R, G, and B light is controlled. These light valves consist of a liquid crystal panel,
By controlling the light transmission of picture elements on the liquid crystal panel,
A monochromatic image is obtained. Light bulb 40R, 40G,
The R, G, and 13 lights transmitted through 40B and made into a monochromatic image enter the cube-shaped tichroic prism 30, are color-combined, and are emitted from the surface 34. The light emitted from the surface 34 is projected onto the screen 43 via the projection lens 42 and displayed on the screen 43 as a color image.

As described above, in the first embodiment, the white light emitted from the lamp 10 passes through the dichroic filters 24 to 26 with 0° incidence, which is less susceptible to the deviation of the incident angle.
Since the colors are separated into R, G, and B components, a clear image without color shift is displayed on the screen 43 of the color synthesis system 2.

Furthermore, as shown in Fig. 7, a polarizing beam splitter can be used in place of the expensive cube-shaped gicchroic prism, making it possible to manufacture a projection type color display device compactly at low cost. Since 20 is formed by bonding two right-angle prisms 21 together, compared to the conventional examples shown in FIGS. 6(b) and 7, there is no joint in the center of the prism or mirror. It is also possible to prevent color unevenness due to scattering of incident light at the joint.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 5, the same or corresponding parts as in FIG. 1 are given the same reference numerals. In FIG. 5, the optical axes of the color separation system 1 and the color synthesis system 2 are arranged parallel to each other and spaced apart from each other. In the color synthesis system 2, the condenser lenses 41R, 41G, and 41B as in the first embodiment are not used. The R, G, and B lights separated by color separation system 1 are
The upper light valve 40R in FIG.
, 40G, and 40B. In this embodiment, the G component light separated by the color separation system 1 is also incident on the light valve 40G via the total reflection mirror 27. The color synthesis system 2 functions in the same manner as the embodiment shown in FIG. 1, and a color image is obtained.

In this example as well, a projection type color display device was obtained which has the characteristics of being compact and low cost with little color unevenness.

Note that the present invention is not limited to the above-mentioned two actual flow sides, and for example,
As a light valve, other simple matrix type liquid crystal display panels (ferroelectric LCD5STN-LCD, etc.) and active matrix type liquid crystal display panels (TPT-LCD, M
IM-LCD, etc.) can be used, and a scattering type liquid crystal panel can also be used as one that does not use a polarizing plate.

(Effects of the Invention) As described above, the projection type color display device of the present invention uses a 0° incidence type dichroic filter that is less affected by deviations in the incident angle of light, so it can display white light without color unevenness. It can be separated into RSG and B components. Therefore, the projection type color display device of the present invention can display clear, high-quality images.

[Brief explanation of the drawing]

1 is a block diagram showing a projection type color display device according to a first embodiment of the present invention, FIG. 2 is a block diagram showing a color separation system of the display device in FIG. 1, and FIG. 3 is a block diagram showing the color separation system of the display device of FIG. An explanatory diagram showing the principle of color separation of polarized light components. Fig. 4 is an explanatory diagram showing the principle of color separation of P polarized light components of incident light. Fig. 5 is a projection type color according to the second embodiment of the present invention. A configuration diagram showing the display device, Fig. 6 (
a), (b), and FIG. 7 are block diagrams showing conventional examples of color separation systems, and FIG. 8 is a diagram for explaining the spectral characteristics of a conventional dichroic mirror. 1... Color separation system, 2... Color synthesis system, 10... Lamp, 20... Polarizing beam splitter, 23R, 23G
. 23B... Quarter wavelength plate, 24... 0° incidence R transmission dichroic filter, 25... 0° incidence G transmission dichroic filter, 26... 06 person incidence transmission dichroic filter, 30. ... Cube dichroic prism, 40R, 40G, 40B... Liquid crystal panel, 42... Projection lens, 43... Screen 0 Above Figure 8 Figure 2 Figure 3 Figure 5 Figure 4 Figure 6 (a) Figure 6 (b) M-Figure 7

Claims (1)

[Scope of Claims] 1. A color separation system that separates white light emitted from a light source into three primary color lights of R, G, and B; and 3.
A projection type color display device comprising a light valve that controls transmission of each of the primary colors of light, and a color synthesis system that combines the three primary colors of light transmitted through the light valve, the color separation system comprising: a polarizing beam splitter that separates white light incident from a light source into an S-polarized component and a P-polarized component and outputs the polarized light; A quarter-wave plate is provided with the optical axis tilted at an angle of 45 degrees with respect to the direction, and each of the quarter-wave plates is arranged on the opposite side of the polarizing beam splitter, and the incident angle is 0 degrees. 0° incidence R that allows only R, G, and B light to pass through.
A projection type color display device comprising a transmission dichroic filter, a 0° incidence G transmission dichroic filter, and a 0° incidence B transmission dichroic filter.