JPH0590440U - LCD projector device - Google Patents

Abstract

(57) [Abstract] [Purpose] The changes in the spectral characteristics caused by the difference in the incident angles to the dichroic mirrors for color separation and color synthesis are canceled out to reduce the color unevenness on the projection screen. [Structure] A concave lens 17 is arranged between the ultraviolet / infrared cut filter 3 and the color separation dichroic mirror 4, and the color separation dichroic mirrors 4 and 5 are divergent light.
When the color combining dichroic mirrors 14 and 15 are incident as focused light, the spectral characteristics of the color separating and color combining dichroic mirrors 4, 5, 14, and 15 are shifted in a direction in which they cancel each other out, and the liquid crystal light valve 11, 12,
The difference in the spectral transmittance of the monochromatic optical path with respect to the light passing through each part of 13 is reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a liquid crystal projector device, and more particularly to a color liquid crystal projector device using a dichroic mirror.

[0002]

[Prior Art]

 FIG. 7 shows a conventional color liquid crystal projector device. The light emitted from the light source 1 is removed from ultraviolet rays and infrared rays by the cold mirror 2 and the ultraviolet / infrared cut filter 3 to form a color separation optical system (hereinafter referred to as a color separation dichroic mirror) 4, 5 is separated into three colors of red (hereinafter referred to as R), green (hereinafter referred to as G), and blue (hereinafter referred to as B), and each separated light is reflected directly or by the mirror 6. After that, the light condensed by the condenser lenses 8, 9 and 10 irradiates the three liquid crystal light valves 11, 12 and 13, respectively, and the light transmitted through the respective liquid crystal light valves 11, 12 and 13 is directly or through the mirror 7. After being reflected by, the dichroic mirrors (hereinafter, referred to as color combining dichroic mirrors) 14 and 15 forming a color combining optical system are combined, and a projection lens 16 is used to form a screen (not shown). The image is projected on. The conventional liquid crystal projector emits parallel light from the light source 1, and the color separation dichroic mirrors 4 and 5 transmit or reflect the parallel light. In the color combining dichroic mirrors 14 and 15, the condensed light is condensed by the condenser lenses 8, 9 and 10, and the focused light is transmitted or reflected.

[0003]

[Problems to be solved by the device]

 By the way, in a color liquid crystal projector using a dichroic mirror, each color of R, G, and B is obtained by multiplying the spectral characteristics of the color separation dichroic mirrors 4 and 5 and the spectral characteristics of the color composition dichroic mirrors 14 and 15. It is determined by the spectral characteristics (hereinafter, referred to as the spectral characteristics of the monochromatic optical path). Further, the dichroic mirror generally has a property that the spectral characteristic shifts as shown in FIG. 12 when the incident angle of light changes. In the conventional liquid crystal projector device, the parallel light is transmitted through the color separation dichroic mirrors 4 and 5, and the focused light is transmitted through the color combination dichroic mirrors 14 and 15, so that the light transmitted through the upper portions of the liquid crystal light valves 11, 12, and 13 is transmitted. The incident angles of light passing through the lower part with respect to the dichroic mirrors are the same for the color separation dichroic mirrors, and different for the color combining dichroic mirrors 4 and 5. Therefore, as shown in FIG. 8, for the light passing through the upper portions of the liquid crystal light valves 11, 12, and 13, the spectral characteristics of the color combining dichroic mirrors 14 and 15 shift to the long wavelength side, and FIG. As shown, the spectral characteristics of the color separation and color combining dichroic mirrors do not shift with respect to the light transmitted through the central portions of the liquid crystal light valves 11, 12, and 13. As shown in FIG. As for the light transmitted through the lower portions of 11, 12, and 13, the spectral characteristics of the color combining dichroic mirrors 14 and 15 are shifted to the short wavelength side, so that the liquid crystal light valves 11, 12, and 13 of FIG. There is a problem in that the spectral characteristics of the monochromatic optical paths for the light passing through the upper part, the central part, and the lower part are different, and color unevenness occurs.

Further, for example, as disclosed in JP-A-63-106785, there is a liquid crystal projector device in which incident light to a color separation optical system is focused light and incident light to a color combining optical system is divergent light. Although considered, the difference in the spectral characteristics of the color separation and color synthesis dichroic mirrors is not taken into consideration, and therefore the problem of color unevenness has not been solved.

Therefore, an object of the present invention is to provide a liquid crystal projector device in which the variation of the spectral characteristic of the monochromatic optical path is reduced and the color unevenness on the projection screen is reduced.

[0006]

[Means for Solving the Problems]

 Therefore, according to the present invention, in order to achieve the above-mentioned object, divergent light or convergent light from a light source is incident on two dichroic mirrors forming a color separation optical system to be converted into red, green and blue lights. The separated light is modulated by a liquid crystal light valve and emitted as focused light or divergent light, and this light is combined by two dichroic mirrors forming a color combining optical system, and the combined light is generated. In a liquid crystal projector device for projecting light onto a screen with a projection lens, the color separation optical system and the color synthesis optical system are arranged in directions in which their mutual spectral characteristics are corrected.

[0007]

[Action]

 In the above configuration, since the color separation side is divergent light and the color combination side is focused light, the light separating characteristic of the color separation dichroic mirror is short wavelength side for the light transmitted through the upper part of the liquid crystal light valve. The spectral characteristics of the dichroic mirror for use shift to the long wavelength side.

Spectral characteristics of light transmitted through the central portion of the liquid crystal light valve are not shifted in both the color separating and color combining dichroic mirrors.

For light transmitted through the lower portion of the liquid crystal light valve, the spectral characteristic of the color separation dichroic mirror shifts to the long wavelength side, and the spectral characteristic of the color combining dichroic mirror shifts to the short wavelength side.

Therefore, the change in the spectral characteristic of the monochromatic optical path with respect to the light transmitted through the upper part, the central part and the lower part of the liquid crystal light valve is reduced. As a result, color unevenness on the projection screen is reduced and uniform and beautiful images can be obtained.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a liquid crystal projector device. The light emitted from the light source 1 is removed from ultraviolet rays and infrared rays by the cold mirror 2 and the ultraviolet / infrared cut filter 3, diverged by the concave lens 17, and then separated by the dichroic mirrors 4 and 5 for color separation into R, G and B. The light is separated into three colors, and the separated lights are reflected directly or by the mirror 6, and then are condensed by the condenser lenses 8, 9 and 10 to irradiate the three liquid crystal light valves 11, 12 and 13 respectively. The light transmitted through the liquid crystal light valves 11, 12, and 13 is reflected directly or by the mirror 7, and then is combined by the dichroic mirrors 14 and 15 for color combination, and an image is displayed on a screen (not shown) by the projection lens 16. Projected.

FIG. 2 is a diagram in which, for example, a blue monochromatic optical path is simplified by converting reflection into transmission. The parallel light emitted from the light source 1 is removed from ultraviolet rays and infrared rays by the cold mirror 2 and the ultraviolet / infrared cut filter 3, diverged by the concave lens 17, transmitted through the color separation dichroic mirrors 4 and 5, and then collected by the condenser lens. The light is transmitted through the liquid crystal light valve 13, the mirror 7, and the color combining dichroic mirror 15, and enters the projection lens 16.

By arranging the concave lens 17 between the ultraviolet / infrared cut filter 3 and the color separation dichroic mirror 4, divergent light is emitted to the color separation dichroic mirrors 4 and 5 and to the color synthesis dichroic mirrors 14 and 15. The focused light is transmitted or reflected by the liquid crystal light valves 11, 12, and the spectral characteristics of the color separation dichroic mirrors 4, 5 and the color combination dichroic mirrors 14, 15 as shown in FIGS. 3, 4 and 5. This is different for light transmitted through the upper part, the central part and the lower part of 13, and it is possible to reduce the change in the spectral characteristic of the monochromatic optical path as shown in FIG. As a result, color unevenness on the projection screen is reduced, and a uniform and beautiful image can be obtained.

[0014]

[Effect of the device]

 According to the present invention, since the color separation side is the divergent light and the color synthesis side is the focused light, the change in the spectral characteristic of the monochromatic optical path with respect to the light transmitted through each part of the liquid crystal light valve is reduced. As a result, color unevenness on the projection screen was reduced and uniform and beautiful color images could be obtained.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a liquid crystal projector device showing an embodiment of the present invention.

FIG. 2 is a simplified diagram of a monochromatic blue optical path according to FIG.

3 is a spectral characteristic diagram of a dichroic mirror for color separation and color combination with respect to light transmitted through an upper portion of the liquid crystal light valve according to FIG.

FIG. 4 is a spectral characteristic diagram of a dichroic mirror for color separation and color combination with respect to light transmitted through the central portion of the liquid crystal light valve according to FIG.

5 is a spectral characteristic diagram of a dichroic mirror for color separation and color combination with respect to light transmitted through a lower portion of the liquid crystal light valve according to FIG.

6 is a spectral characteristic diagram in the monochromatic optical path according to FIG.

FIG. 7 is a configuration explanatory view of a conventional liquid crystal projector device.

8 is a spectral characteristic diagram of a dichroic mirror for color separation and color combination with respect to light transmitted through the upper portion of the liquid crystal light valve according to FIG.

9 is a spectral characteristic diagram of a dichroic mirror for color separation and color combination with respect to light transmitted through the central portion of the liquid crystal light valve according to FIG.

10 is a spectral characteristic diagram of a dichroic mirror for color separation and color combination with respect to light transmitted through a lower portion of the liquid crystal light valve according to FIG.

FIG. 11 is a spectral characteristic diagram in the monochromatic optical path according to FIG. 7.

FIG. 12 is a spectral characteristic diagram of a dichroic mirror.

[Explanation of symbols]

1 Light Source 2 Cold Mirror 3 Ultraviolet / Infrared Cut Filter 4, 5 Color Separation Optical System (Color Separation Dichroic Mirror) 6, 7 Mirror 8, 9, 10 Condenser Lens 11 Red Liquid Crystal Light Valve 12 Green Liquid Crystal Light Valve 13 Blue Liquid crystal light valve for use 14, 15 Color combining optical system (color combining dichroic mirror) 16 Projection lens 17 Concave lens

Claims (1)

[Scope of utility model registration request] 1. Divergent light or convergent light from a light source is incident on two dichroic mirrors forming a color separation optical system and separated into red, green and blue lights, and the separated lights are separated by a liquid crystal light valve. In the liquid crystal projector device, the modulated light is emitted as focused light or divergent light, the light is combined by two dichroic mirrors forming a color combining optical system, and the combined light is projected on a screen by a projection lens. A liquid crystal projector device in which a separation optical system and a color synthesis optical system are arranged in directions in which their mutual spectral characteristics are corrected.