JPS63265218A - Projection type display device - Google Patents

Abstract

PURPOSE:To correct color temp. so as to have high color temp. by setting the optical path lengths of 3 sheets of liquid crystal light valves and white light source at the lengths longest in the color light of the high intensity of the white light source and shortest in the white light of the small intensity of the white light source. CONSTITUTION:The optical path lengths of 3 sheets of the liquid crystal light valves 101-103 and the light source 104 are set at the lengths longest in the white light of the high intensity of the light source and shortest in the color light of the small intensity of the light source. Since the color light of the high intensity is set long in the optical path length up to the liquid crystal light valves, said light receives the largest light loss and the intensity of the incident light on the liquid crystal light valves attains the value smaller than the value at the time of emission from the light source. On the other hand, the color light of the small intensity is set short in the optical path length up to the liquid crystal light valves and, therefore, the light loss is small and the intensity of the incident light on the light valves is hardly changed from the intensity of the exit light from the light source. The intensities of the respective color light rays emitted from the liquid crystal light valves are, therefore, nearly equal and the color temp. of the projected light is increased.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a projection display device.

[Conventional technology]

Projection type display tA using a conventional liquid crystal light valve is disclosed in Japanese Patent Application Laid-open No. 80-179723 and Japanese Patent Application Laid-open No. 61-15048.
As shown in Figure 7, the white light from the light source is separated into red (R), green (G), and blue (CB) by a dichroic mirror system, image formation is performed by a liquid crystal light valve, and then color synthesis is performed by a dichroic mirror system. The projection is magnified.

When active matrix liquid crystal light pulp is used in the liquid crystal light valve, a color projected image with high resolution and high contrast ratio can be obtained.

(Problems to be Solved by the Invention) However, the above-mentioned prior art has a problem in that the color temperature of the projected image is significantly lower than that of a CRT projection device. That is, since the intensity of the light source used has a wavelength distribution, it is difficult to set the color temperature high.

This is particularly a problem when using halogen lamps, metal halide lamps, etc., which are easy to handle and relatively inexpensive.

The present invention solves the above-mentioned problem, and provides a projection display device that corrects color temperature by optimizing the optical configuration within the projection display device according to the color intensity of the light source and has a high color temperature. The purpose is to obtain.

[Means for solving problems]

The projection type display device of the present invention is a projection type comprising a white light source, a three primary color separation dichroic mirror system, three liquid crystal light valves for forming an image using the three primary colors, a color synthesis dichroic mirror system, and a projection lens. The display device is characterized in that the optical path length between the three liquid crystal light valves and the light source is set to be the longest for color light of high intensity from the light source and the shortest for color light of low intensity from the light source.

[Effect]

According to the configuration of the present invention, the color light with high intensity has a long optical path length to the liquid crystal light valve, and therefore suffers the most optical loss. becomes. On the other hand, for colored light with low intensity, the optical path length to the liquid crystal light valve is set short, so the optical loss is small and the light intensity incident on the liquid crystal light valve is almost the same as the light emitted from the light source. Therefore, the intensity of each color light emitted from the liquid crystal light valve is approximately equal, and the color temperature of the projected light becomes high.

[Example 1] FIG. 1 is an optical configuration diagram of a projection type display device in this example. FIG. 2 is a diagram showing the output intensity wavelength distribution of the halogen lamp used in the projection type display device of this embodiment and the output intensity distribution wavelength of the projected image. This embodiment will be described below with reference to FIGS. 1 and 2.

The driving means used in the liquid crystal light valve used in this example was a substrate on which polysilicon thin film transistors, amorphous silicon thin film transistors, MIM elements, etc. were formed in a matrix, and a twisted nematic (TN) liquid crystal was grown. It is an active matrix TN liquid crystal light pulp that holds. Each liquid crystal light valve has a TN liquid crystal multiplayer batting rate Δn that changes depending on the incident color light. For a cell with a cell thickness of d or 7 μm, Δ for red color
n=0.214, 020 for green color.

1. TNi with a value of Δn=0.1e5 for blue color
A light bulb was used to hold the image, and the settings were made to obtain a high contrast ratio. The projection display He of this embodiment uses a halogen lamp as a light source. The output intensity of a halogen lamp on the short wavelength side (blue) is significantly weaker than in other wavelength regions. In other words, it is perceived as yellow overall, and the color temperature is as low as 3000. In this implementation example, the liquid crystal light valve 101 for red light; the liquid crystal light valve 102 for green light
The blue liquid crystal light valves 103 were arranged at different distances m from the halogen lamp light source 104, as shown in FIG. Red light liquid crystal light valve 101 and light source 1
The optical path length between the blue liquid crystal light valve 103 and the light source is the shortest. With this configuration, compare the output intensity from the halogen lamp and the light intensity distribution on the screen. The result is shown in Figure 2.The wavelength distribution characteristics became almost uniform over the entire wavelength range, and the color temperature of the output light was improved to approximately 6000. By changing the optical path length between the light source and the light source according to the light source intensity wavelength distribution, it has been corrected and made uniform, resulting in a high value.Furthermore, the amount of incident light for each color of red, green, and blue light has become almost uniform. This makes it possible for this projection display device to provide projected images with excellent gray scale display and excellent color reproducibility.

[Example 2] Figures 3 and 4 show optical configuration diagrams of the projection display device of this example.
Shown below. This embodiment will be described below using FIGS. 3 and 4.

In this example, each liquid crystal light valve was obtained in the same manner as in Example 1. A metal halide lamp was used as the light source of the projection display device. The metal halide lamp used in this example has the strongest intensity in the red wavelength region and the weakest in blue light. In particular, the intensity of red light is significantly higher than that of other colored lights. There are two means for color temperature correction as described below, and their configurations are shown in FIGS. 3 and 4.

In the configuration shown in FIG. 3, the red light liquid crystal light valve 101 and the metal halide lamp 304 have the longest optical path length, and the green liquid crystal light valve 102, the blue liquid crystal light valve 103, and the metal halide lamp have the same optical path length. . With this configuration, the output light intensity distribution is fairly uniform and the color temperature is improved. Furthermore, if necessary, it is also possible to make the color temperature higher. That is, an optical configuration as shown in FIG. 4 may be used. In FIG. 4, the optical path lengths of the liquid crystal light valve 101 for red light, the liquid crystal light valve 102 for green light, the liquid crystal light valve 103 for blue light, and the metal halide lamp 304 are set to become gradually smaller. Any projection type display device having an optical configuration as shown in FIGS. 3 and 4 achieves the object of the present invention and can obtain images with high color temperature. Furthermore, with the configuration of this embodiment, it is also possible to obtain a projected image with excellent gray scale and color reproducibility.

〔Effect of the invention〕

In the optical configuration of the projection display device of the present invention, the light intensity wavelength distribution of the light source can be corrected by changing the optical path length between the light source and each liquid crystal light valve. Therefore, the projected image of the projection type display device of the present invention has an effect of having a very high color temperature. Furthermore, since the amounts of incident light of red, green, and blue are almost uniform, the images of the projection type display device of the present invention have excellent gray scale display, and also have the effect of having good color balance and excellent color reproducibility.

[Brief explanation of drawings]

FIG. 1 is an optical configuration diagram of a projection type display device in Example 1. 101... Red liquid crystal light bulb 102...
... Green liquid crystal light valve 103 ... Blue liquid crystal light valve 104 ... Halogen lamp 105 ... Dichroic mirror prism 10
Dichroic mirror Figure 2 shows the light intensity wavelength distribution diagram of the halogen lamp and the projected image. FIG. 3 is an optical configuration diagram of a projection type display device in Example 2. 304...metal halide lamp FIG. 4 is an optical configuration diagram of a projection type display device in Example 2. that's all

Claims (1)

[Claims] In a projection display device consisting of a white light source, a three primary color separation dichroic mirror system, three liquid crystal light valves for forming an image using the three primary colors, a color synthesis dichroic mirror system, and a projection lens, the three liquid crystals are A projection type display device characterized in that the optical path length between a light valve and a white light source is set to be longest for colored light of high intensity of the white light source and shortest for colored light of low intensity of the white light source.