JPH06208099A - Liquid crytal projector - Google Patents

Abstract

PURPOSE:To decrease the number of clichroic filters to be installed by forming a spectral optical system and a synthesizing optical system into a two-layered structure and integrating the dichroic filters of both optical systems. CONSTITUTION:This liquid crystal projector consists of the spectral optical system 12 which separates the light from a light source 11 to plural color light rays, liquid crystal display panels 13 to 15 which display the images corresponding to the respective colors, the synthesizing optical system 16 which synthesizes the plural color images transmitted through the respective liquid crystal display panels 13 to 15 and a projecting lens 18 which projects the synthesized color images. The spectral optical system 12 and the synthesizing optical system 16 are superposed to the two-layered structure and are disposed. In addition, reflecting means 22 to 24 which reflect the respective color light rays separated by the spectral optical system 12 to the synthesizing optical system 16 are provided and the dichroic filters 21 of the spectral optical system 12 and the synthesizing optical system 16 are integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector in which light from a light source is decomposed by a dichroic filter, and color images illuminating a plurality of liquid crystal display panels are combined by the dichroic filter and projected by a projection lens. .

[0002]

2. Description of the Related Art Conventionally, a liquid crystal projector for projecting a magnified image generally decomposes light from a light source into a plurality of colors by a spectroscopic optical system equipped with a dichroic filter, and each separated color light corresponds to each color. The liquid crystal display panel for displaying an image is illuminated, the color image transmitted through each liquid crystal display panel is combined by a plurality of dichroic filters of the combining optical system, and projected on a screen through a projection lens.

Further, the dichroic filter is for separating and combining light by selectively reflecting and transmitting colors on a surface having a dichroic coat,
To separate into 3 colors or to combine 3 colors, 2 for each
A type of dichroic filter is needed.

In the example of the liquid crystal projector 50 shown in FIG. 5, the light emitted from the light source 11 is converted into red R, green G and blue B by the red reflection dichroic filter 51 and the green reflection dichroic filter 52 of the spectroscopic optical system 12. Then, the optical path of red light is changed by the total reflection mirror 53. Also,
Liquid crystal display panels 13 to 15 for displaying respective images on the disassembled optical paths are arranged to transmit and illuminate with each color light, and further, the optical path of the blue image is changed by the total reflection mirror 54, the red, green, It is known that blue color images are combined by the red-green reflection dichroic filter 55 and the green reflection dichroic filter 56 of the combination optical system 16 and the combined light is projected by the projection lens 18.

Further, in another example of the liquid crystal projector 60 shown in FIG. 6, the light from the light source 11 is similarly red R, green G and blue by the red reflection dichroic filter 51 and the green reflection dichroic filter 52 of the spectroscopic optical system 12. The light is divided into three colors of B, and then the optical paths are changed by three total reflection mirrors 53, 62 and 63 so as to enter the central portion, and the liquid crystal display panels 13 to 15 are illuminated with the respective colored lights. Further, it is also known that each color image is combined by the cross type dichroic mirror 61 in which the red reflection dichroic mirror 61a and the blue reflection dichroic mirror 61b of the combination optical system 16 are combined so as to be orthogonal to each other, and the projection lens 18 projects the images. Has been.

[0006]

However, the dichroic filter in the conventional liquid crystal projector having the arrangement represented by FIG. 5 as described above has two spectroscopic optical systems and two synthetic optical systems for a total of four. In addition, the lens back focal length is long, the installation space is large, the entire liquid crystal projector is large, and the number of expensive dichroic filters is increased, resulting in a high manufacturing cost.

The cross dichroic filter represented by FIG. 6 can be miniaturized, but the illumination distance varies depending on the channel so that the blue light path becomes longer than the other light paths, and the color unevenness is caused. Occurs, which makes it difficult to achieve white balance.

Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a liquid crystal projector in which the number of dichroic filters to be installed is reduced and color unevenness is small even when a cross dichroic filter is used. To do.

[0009]

In order to achieve the above object, a liquid crystal projector of the present invention includes a spectroscopic optical system having a dichroic filter for separating light from a light source into a plurality of color lights and performing a plurality of color illumination. A plurality of liquid crystal display panels for image formation for displaying an image corresponding to each separated color, and a dichroic filter for synthesizing a plurality of color images illuminated by the respective color lights and transmitted through the respective liquid crystal display panels. It consists of a combination optical system and a projection lens that projects the combined color image onto the screen.
The spectroscopic optical system and the synthetic optical system are arranged in a two-layer structure so as to overlap each other, and a reflecting means for reflecting each color light decomposed by the spectroscopic optical system to the synthetic optical system is provided. It is configured by integrating a dichroic filter.

Further, in disposing the spectroscopic optical system in one layer and the combining optical system in the other layer, the projection lens is disposed in parallel with the light source of the illumination light source section with the optical axis toward the center. , A cross dichroic filter that extends from one layer to the other layer in the central portion to decompose the light from the light source into three directions and combine the light from the three directions to the projection lens side,
Each of the three ends has 18 rays of light from one layer to the other.
It is preferable that the reflecting means for reflecting 0 degree is provided, and the liquid crystal display panel is provided between the reflecting means and the cross dichroic filter in the other layer.

[0011]

In the liquid crystal projector as described above, the spectroscopic optical system and the combining optical system are formed in two layers, the dichroic filters of both optical systems are integrated, and the light emitted from the light source is the spectroscopic optical system side of the dichroic filter. Is separated into each color in the part of, and each color light is reflected by the reflecting means to the combining optical system, and after illuminating the liquid crystal display panel respectively, the respective colors are combined in the part of the combining optical system side of the dichroic filter, and the combined color is obtained. The image is projected and imaged by a projection lens, and even if a cross-shaped dichroic filter is used, the illumination distance of each color channel can be made equal to reduce the occurrence of color unevenness, and the adoption of a two-layer structure enables a compact configuration. In addition, the number of expensive dichroic filters installed can be reduced to make it possible to configure an LCD projector at low cost. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic overall configuration of an optical system of a liquid crystal projector. The color arrangement is an example.

The liquid crystal projector 10 includes a spectroscopic optical system 12 for separating the light from the light source 11 into a plurality of color lights, liquid crystal display panels 13 to 15 for displaying an image corresponding to each of the separated colors, and illumination with each color light. A combination optical system 16 for combining the color images transmitted through the liquid crystal display panels 13 to 15 and a projection lens 18 for projecting the combined light on a screen (not shown) are provided.

The spectroscopic optical system 12 and the combining optical system 16 have a two-layer structure, that is, as shown in the side structure partially omitted in FIG. 2, the spectroscopic optical system 12 is in the lower layer and the combining optical system 16 is in the upper layer. It is arranged and configured. Both optical systems 12 and 16 share a cross-shaped dichroic filter 21 (cross dichroic mirror) integrally formed. The cross-shaped dichroic filter 21 has a red reflection dichroic mirror 21a and a green reflection dichroic mirror 21b that intersect each other in a cross shape and are long in the vertical direction.

As shown in the plane structure of FIG. 3, the spectroscopic optical system 12 uses the light (white light) emitted from the light source 11 in the red region by using the lower layer side region of the cross-shaped dichroic filter 21. The reflection dichroic mirror 21a reflects red light to the red channel R side, and the green reflection dichroic mirror
21b reflects the green light to the green channel G side and the blue light to the blue channel B in front of the cross dichroic filter 21.
It is transmitted to the side and decomposed into three colors.

The separated color lights are reflected by the reflecting means 22 to 24 arranged at the ends of the channels R, G and B, respectively.
Are reflected to the upper side synthetic optical system 16 side. The reflecting means 22 to 24 include lower tilting mirrors 22a to 24a for reflecting the light of the spectroscopic optical system 12 upward and the lower tilting mirror 22a.
Cross-type dichroic filter for light reflected at ~ 24a
Upper tilted mirrors 22b to 24 that reflect toward the center toward 21
It is composed of a total reflection mirror for changing the optical path by b, and the optical path of the incident light is converted by 180 degrees by the reflection means 22 to 24 by the orthogonal total reflection mirror and reflected to the upper layer side.

Further, as shown in FIG. 4, the structure of the upper layer portion is such that the condenser lens 25 and the liquid crystal display panels 13 to 15 are provided on the optical paths following the reflecting means 22 to 24 of the respective color channels R, G and B.
Are arranged respectively. Liquid crystal display panel 13 to 15
Are for displaying images corresponding to respective colors of red, green and blue, and are transmitted and illuminated by the respective color lights separated by the spectroscopic optical system 12.

On the other hand, the synthesizing optical system 16 uses the upper portion of the cross type dichroic filter 21 and uses the red channel R reflected by the red reflection dichroic mirror 21a.
From the green channel G reflected by the green reflection dichroic mirror 21b and the blue light from the blue channel B transmitted through the cross-shaped dichroic filter 21 to obtain a color image. The light combined by the cross-shaped dichroic filter 21 is enlarged and projected on a screen (not shown) by the projection lens 18.

According to the embodiment as described above, the cross-shaped dichroic filter 21 is used to dispose the spectroscopic optical system 12 and the combining optical system 16 in a two-layer structure, so that each color channel R, G, Since the optical path length in B, that is, the illumination distance can be made equal, the occurrence of color unevenness can be reduced and a good projected image can be obtained.

Although the dichroic filter 21 in the above embodiment is composed of a mirror, it may be composed by forming a similar reflection coat layer on a predetermined surface of the prism.

[0021]

According to the liquid crystal projector of the present invention, the spectroscopic optical system and the synthetic optical system are arranged in a two-layer structure, and the dichroic filters for both are integrally provided.
The number of dichroic filters as a whole can be reduced,
Manufacturing cost can be reduced. Even if the cross dichroic filter is used, it is possible to reduce the occurrence of color unevenness by making the illumination distance of each color channel equal.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an overall configuration of an optical system of a liquid crystal projector according to an embodiment of the present invention.

2 is a schematic side view showing an optical system of the liquid crystal projector of FIG. 1 with a part thereof omitted.

FIG. 3 is a plan view showing a schematic configuration of a spectroscopic optical system on the lower layer side of FIG.

FIG. 4 is a plan view showing a schematic configuration of a combining optical system on the upper layer side of FIG.

FIG. 5 is a schematic configuration diagram showing an example of a liquid crystal projector according to a conventional technique.

FIG. 6 is a schematic configuration diagram showing another example of the liquid crystal projector according to the related art.

[Explanation of symbols]

 10 Liquid crystal projector 11 Light source 12 Spectral optical system 13 to 15 Liquid crystal display panel 16 Synthetic optical system 18 Projection lens 21 Dichroic filter 22 to 24 Reflecting means

Claims (2)

[Claims] 1. A spectroscopic optical system including a dichroic filter for separating light from a light source into a plurality of color lights to perform a plurality of color illuminations, and an image forming apparatus for displaying an image corresponding to each separated color. A plurality of liquid crystal display panels, a synthesizing optical system having a dichroic filter for synthesizing a plurality of color images that are illuminated by the respective color lights and transmitted through the respective liquid crystal display panels, and project the synthesized color images on a screen. In a liquid crystal projector including a projection lens, the spectroscopic optical system and the synthetic optical system are arranged in a two-layer structure so as to overlap each other, and a reflecting means for reflecting each color light decomposed by the spectroscopic optical system to the synthetic optical system is provided, A liquid crystal projector characterized by integrating the dichroic filter of the spectroscopic optical system and the synthetic optical system. 2. When the spectroscopic optical system is arranged in one layer and the combining optical system is arranged in the other layer, a projection lens is arranged parallel to the light source with the optical axis toward the center, and A cross dichroic filter that extends from one layer to the other layer and decomposes light from the light source into three directions and synthesizes light from the three directions on the projection lens side is provided. Reflecting means for reflecting light from one layer to the other layer by 180 degrees are respectively arranged, and liquid crystal display panels are respectively arranged between the reflecting means and the cross type dichroic filter in the other layer. Claim 1 characterized by the above-mentioned.
The described liquid crystal projector.