JPH02250048A - Projecting type display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a projection type display device for displaying video images, computer images, etc. Particularly, the present invention relates to a projection type display device for displaying video images, computer images, etc. In particular, a transmission type display device that has excellent contrast and can realize a compact size. The present invention relates to a projection type display device using a bulb.

[Conventional technology]

As a conventional projection type display device using a transmission type light valve, one having a configuration as shown in FIG. 4 has been proposed.
(SID87 DIGEST-75p) A version with 70,400 pixels is planned to be commercialized.

[Problem to be solved by the invention]

However, with the above-mentioned conventional technology, the intensity distribution of the light incident on the three transmission light valves for R, G, and B differs between each of the three transmission light valves, resulting in the following problems. was there.

In the projection type display device having the configuration shown in FIG. 4, the intensity distribution of the three color lights incident on the R, G, and B transmission type light valves is as shown in FIG. 5, for example. That is,
R, G, and B lights are all bright in the center and dark in the periphery, and the way the periphery becomes darker is more INIF in the order of R404B.

Here, in order to achieve white balance, it is necessary to make the intensity distribution of the incident light uniform within the plane of that one transmissive light valve, and also to balance the intensity among the three transmissive light valves. .

Therefore, in order to adjust the imbalance between the former and latter light intensities, a method of adjusting the transmittance of each pixel of the transmission type light valve is required.

That is, first, the intensity of light incident on each pixel is compared within the plane of each transmissive light valve, and the intensity of light emitted from the transmissive light valve within the plane of each transmissive light valve is made equal. (In other words, a pixel with strong incident light intensity is given an in-plane luminance correction signal that gives a lower transmittance than a pixel with weaker incident light intensity, and the colors handled by the transmissive light valve are uniformly displayed on the screen. ) At the same time, the light emitted from the three transmissive light valves is combined to obtain a full-color display screen, but when the original image is completely white, the screen It is also necessary to adjust the transmittance of each transmissive light valve so that the upper display screen becomes white.

(In other words, the color light modifies the transmittance of each pixel of a transmissive light valve, which has a relatively strong output light intensity, to be lower than the transmittance of each pixel of a transmissive light valve, which has a relatively low input light intensity. (The white balance can be maintained on the screen by giving a luminance correction signal between the two.) However, since the light intensity distribution of the illumination system actually used is as described above, among the transmissive light valves that control each color light, Transmissive light valves that control blue light (B) only need to correct the in-plane incident light intensity distribution, whereas transmissive light valves that control green light (G) and red light (R)
Transmissive light valves that control red light (R) have to reduce the overall transmittance in order to correct the in-plane incident light intensity distribution and maintain white balance. is particularly remarkable.

For this reason, a transmissive light valve for controlling red light has a considerable part of its original gradation display capability used for in-plane luminance correction and color-to-color luminance correction, which reduces its gradation display capability. There was a problem that the display quality on the screen deteriorated.

Therefore, the present invention has been made to solve such problems.

[Means to solve the problem]

The projection type display device of the present invention includes three transmission type light valves for R, G, and B. It is characterized by having a convex lens arranged in it.

[Effect]

The projection type display device configured as described above is, for example, R
Since a convex lens is placed in front of the transmissive light valve for R, the intensity distribution of the light emitted from the transmissive light valve for R changes from the light emitted from the transmissive light valve for B due to the action of the convex lens. The intensity distribution will be the same, and the in-plane brightness correction signal for R will be the same as the brightness correction signal for B.
The circuit becomes simpler, and the luminance distribution of the emitted light is substantially improved. Further, there is no need to provide an inter-color luminance correction signal for white balance, so there is no reduction in gradation display ability, and as a result, the display quality on the screen is improved.

As mentioned above, the above effect can be obtained by placing the convex lens in front of the R transmission light valve, which has a light intensity distribution that is most different from the light intensity distribution incident on the B transmission light valve surface. However, the above effect can be further enhanced by arranging a convex lens having a similar effect.

In addition, even in a projection type display device having a light intensity distribution similar to that described above, the same effect as in the above example can be obtained by placing a convex lens in the optical path of a transmission type light valve that has a large in-plane light intensity distribution of incident light. can get.

〔Example〕

Hereinafter, the present invention will be described in detail based on Examples. However, the present invention is not limited to the following examples.

(Example 1) FIG. 1 is a diagram showing the configuration of a projection type display device of the present invention. 1 is a light source, 2 is a dichroic mirror, 3 is a reflective mirror, and 4 is a transmission type light valve.

5 is a dichroic prism, and 6 is a projection lens.

7 is a screen, and 8 is a convex lens.

For comparison, FIG. 4 shows a configuration diagram of a conventional projection type display device. As can be seen from FIG. 0, there is no convex lens.

Next, in FIG. 5, for R included in the conventional projection display device,
As can be seen from Figure 0, which shows the light intensity distribution of light incident on the G and B transmission type light valves, it is bright in the center and dark in the periphery. Further, it can be seen that the light intensity distribution becomes non-uniform in the order of R→G-1-H. Moreover, it can be seen that the intensity of each color light at the center is the strongest in R, followed by G, and the darkest in B.

Based on the above-mentioned light intensity distribution, conventional projection display devices require in-plane brightness correction and inter-color brightness correction when uniformity of screen brightness and absence of color unevenness are particularly required. I am doing it. Therefore, as mentioned earlier, a considerable portion of the gradation display capability that each transmissive light valve originally has is lost for these corrections, which reduces the gradation display capability and improves the quality of the display on the screen. and the brightness of the screen was decreasing.

On the other hand, FIG. 3 shows the intensity distribution of light incident on the R, G, and B transmission type light valves included in the projection display device of the present invention. Because the convex lens is placed in front of the R transmission light valve, the intensity distribution of the light that enters the R transmission light valve changes and is almost the same as the intensity distribution of the light that enters the B transmission light valve. It became the same. Therefore, the in-plane brightness correction for R can be shared with the in-plane brightness correction for B, the circuit becomes simple, and the brightness distribution of the emitted light becomes substantially uniform.

Therefore, the gradation display capability of the R transmission type light valve has been improved, and as a result, the visual quality of the display on the screen has improved.

Here, we have shown an example in which a convex lens is placed in front of the transmissive light valve for R, but if the type of light source or the configuration of the optical system is different from the above, then In some cases, it may be better to place a convex lens in the

(Example 2) In Example 1, a convex lens with high absorbance at the periphery and low absorbance at the center was placed in front of the R transmission type light valve to improve display quality, but this example Then, a convex lens having a similar effect was also placed in front of the transmission type light valve for G. In this case, display quality even higher than that obtained in Example 1 was obtained.

〔Effect of the invention〕

The projection type display device of the present invention includes three transmission type light valves for R, G, and B. Because a convex lens is placed in the screen, the intensity distribution of the light incident on each transmissive light valve is more uniform for each color light compared to conventional projection display devices, increasing the gradation display ability, and as a result, the screen This has the effect of improving the quality of the image displayed above.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a projection type display device in Embodiment 1 of the present invention. FIG. 2 is a diagram showing a convex lens in Example 1 of the present invention. FIG. 3 is a diagram showing the intensity distribution of light incident on each transmission type light valve of the projection type display device in Example 1 of the present invention, (
(a) is red, (b) is green, (C) is blue.) Fig. 4 is a diagram showing the configuration of a conventional projection type display device. FIG. 5 is a diagram showing the intensity distribution of light incident on each transmission type light valve of a conventional projection type display device. ((a) is red, (b) is green, (C) is blue, )1
...Light source 2...Dichroic mirror 3...Reflection mirror 4...Transmissive light valve 5...Dichroic prism 6...Projection lens 7...Screen 8...Convex lens or higher Whistle/ Illustrated Stone Criminal One Trap - Totosun (αn(t) CG) Neta Diagram

Claims (1)

[Claims] A projection display device including three transmissive light valves for R, G, and B, characterized in that a convex lens is disposed in the optical path of at least one of the three transmissive light valves. A projection display device.