JPH02196231A - Projecting type display device - Google Patents

Abstract

PURPOSE:To improve the quality of image displayed on a screen, upgrading the gradation displaying ability of the display device by placing in the optical path of at least one of light transmitting type light values for each of R, G, and B of the projecting type display device, a filter which has absorbancy distribution inside the surface. CONSTITUTION:Dichroic mirrors 2, reflecting mirrors 3, and the light transmitting type light values 4, each for R, G, and B, are placed corresponding to a light source 1 of the projecting type displaying device. A projecting lens 6 is placed through a dichroic prism 5 against each light transmitting type light valve 4, and the image projected on the projecting lens 6 is projected on the screen 7. The filter 8, which has absorbed light quantity in the luminous intensity distribution high in the peripheral part and low in the central part is placed in between the reflecting mirrors 3, in the optical path of the transmitting type light value 4 for the display device R of this constitution, changing the luminous intensity distribution of the light made incident on the transmitting light value 4 for R, making it approximately the same as the light made incident on the light transmitting type light value 4 for B.

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, computer images, etc. In particular, the present invention relates to a projection type display device using a transmission type light valve, which has excellent contrast and can realize a compact size.

[Prior Art] 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. (
87D GFiST 75p) and number of pixels 7
It is planned to commercialize 0,400 products.

[Problems to be Solved by the Invention] However, in the prior art described above, the intensity distribution of light incident on the five transmission light valves for R, G, and B is different from each other for each of the five transmission light valves. Because of the differences, the following issues arise.

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,
The R, G, and B lights are all bright in the center and dark in the periphery. Further, the darkening in the peripheral area is more noticeable in the order of Re G nil.

Here, in order to achieve white balance, it is necessary to make the intensity distribution of the incident light uniform within the surface of one transmissive light valve, and also to maintain the intensity balance among the five transmissive light valves. Therefore, in order to adjust the imbalance in the intensity of the former and latter lights, a method of adjusting the transmittance of each pixel of the transmissive light valve is required.

First, the intensity of light incident on each pixel within the plane of each transmissive light valve is compared to equalize the intensity of light emitted from the transmissive light valve within the plane of each transmissive light valve. (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 five transmissive light valves is combined to obtain a full-color display screen.When the original image is completely white, the light on the screen is It is also necessary to adjust the transmittance of each transmissive light valve so that the display screen becomes white. (In other words, the transmittance of each pixel of a transmissive light valve whose output light intensity is relatively strong is modified to be lower than the transmittance of each pixel of a transmissive light valve whose incident light intensity is relatively low. (The white balance can be maintained on the screen by giving a luminance correction signal between the colors.) However, since the light distribution of the lighting system actually used is as described above, a transmission type light valve that controls each color light is used. Transmissive light valves that control blue light (B) only need to correct the in-plane incident light intensity distribution, while transmissive light valves that control green light (G) and red light (R )
Transmissive light valves that control this require reducing the overall transmittance in order to correct the in-plane incident light intensity distribution and maintain white balance. This is particularly noticeable with respect to transmission type light valves that control red light (R).

For this reason, transmissive light valves for controlling red light use a considerable portion of their original gradation display capacity for in-plane luminance correction and inter-color luminance correction. There was a problem that the display quality on the screen deteriorated and l-mounds occurred.The present invention was made to solve this problem.

[Means for Solving the Problems] A projection type display device of the present invention includes five transmission type light valves for R, G, and B.
The present invention is characterized in that a filter having an in-plane absorbance distribution is disposed in at least one optical path of the transmission type light valves for light, light for G, and light for B.

[Effect] As above! The developed projection type display device has high absorbance at the periphery, for example, in front of the R transmission type light valve.
When a low filter is placed in the center, the light intensity distribution emitted from the transmission type light valve for B is the same, and the in-plane brightness correction signal for R is the same as the brightness correction signal for B. The circuit becomes shorter and the luminance distribution of the emitted light is substantially improved. Furthermore, there is no need to provide an inter-color luminance correction signal for white balance (therefore, there is no reduction in gradation display capability), and as a result, the display quality on the screen is improved.

As described above, by placing the filter in front of the R transmission light valve, which has the light intensity distribution that is most different from the light intensity distribution incident on the B transmission light valve surface,
Although the above results can be obtained, the above results can be further improved by similarly arranging a filter having the same function in front of the transmission type light valve for G.

[Example] Hereinafter, the present invention will be explained in detail using 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 guichroic mirror, 15 is a reflection mirror, 4 is a transmission type light valve, 5 is a guichroic prism, 6 is a projection lens, 7 is a screen, 8. is a filter. The filter number 8 has the structure shown in Figure 2. In other words, the material that absorbs light is dispersed in a structure with high density at the periphery and low density at the center. In addition, a structure in which the thickness of the light-absorbing thin film is thicker at the periphery and thinner at the center is also used. For comparison, FIG. 4 shows a groove diagram of a conventional projection type display device. As can be seen from the figure, there is no filter having the above structure.

Next, in FIG. 5, for R included in the conventional projection display device,
The light intensity distribution of light incident on the G and B transmission type light valves is shown. As you can see from the figure, it is bright in the center and dark in the periphery. In addition, it can be seen that the light intensity distribution becomes uneven in the order of R-+ (1 → B).In addition, the intensity of each color light at the center is the strongest (R is the strongest, followed by G) (It turns out that B is the weakest.

Based on the above-mentioned light intensity distribution, conventional projection display devices perform in-plane brightness correction and inter-color brightness correction. Therefore, as mentioned earlier, a considerable portion of the original gradation display capability of each transmissive light valve is used for correction, which reduces the gradation display capability and reduces the display quality on the screen. (Particularly when a halogen lamp is used as the light source, in the case of a transmission type display device for R). The intensity distribution of light incident on the transmission type light valves for R, G, and B is shown.In order to arrange the above-mentioned filter in front of the transmission type light valve for R, the intensity distribution of the light incident on the transmission type light valve for R is shown. The intensity distribution of the light that enters the light bulb has changed, and is now almost the same as the intensity distribution of the light that enters the transmission type light valve for B. Therefore, the in-plane brightness correction for R is now the same as the in-plane brightness correction for B. This simplifies the circuit and makes the luminance distribution of the emitted light substantially uniform.Furthermore, the relative light intensity at the center is almost the same for R and B, making it easier to maintain white balance. Inter-color luminance correction is also no longer necessary for R.

Therefore, the display capability of the transmission type light valve for R was increased, and as a result, the visual quality of the display on the screen was improved.

Here, we have shown an example of placing a filter 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 it is necessary to place the filter in front of the transmissive light valve for G or B. In some cases, it may be better to place a filter in the

(Example 2) Example 1 showed an example in which a filter 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. Then, further G
A filter with a similar effect was also placed in front of the transmission type light valve. In this case, display quality higher than that obtained in Example 1 was obtained.

In a throw/J-type display device including 05 transmission light valves, a filter having an in-plane absorbance distribution in at least one optical path of the B, G, and B transmission light valves. Because of this arrangement, the gradation display capability is improved compared to conventional projection display devices, and as a result, the quality of images displayed on the screen is improved.

[Brief explanation of the drawing]

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 the configuration of a filter in Example 1 of the present invention. FIG. 5 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. FIG. 4 is a diagram showing the configuration of a conventional projection display device [Effects of the Invention] The projection display device of the present invention has brushes for R, G, and B. FIG. 3 is a diagram showing the intensity distribution of light incident on a type light valve. 1...Light source 2...Dichroi 5...Reflection mirror 4...Transmission type ride pattern 5.・・・・・・
...Guicroic Prism 6...
Projection lens 7...Screen 8---Filter mirror

Claims (1)

[Claims] In a projection display device including three transmissive light valves for R, G, and B, there is a A projection type display device characterized by disposing a filter having an absorbance distribution.