JPH0723985B2 - Projection display device - Google Patents

Description

The present invention relates to a projection display device using two liquid crystal display bodies. [Outline of the Invention] The present invention has high brightness and high resolution. In order to obtain a low-priced projection display device, the projection display device is composed of two liquid crystal display devices, and only one liquid crystal display device is provided with a color filter.

[Conventional technology]

In conventional projection apparatuses using liquid crystal, there are mainly a single panel system and a three panel system. The single-panel system has a feature that the optical system is simple and the price is low, but it is difficult to increase the resolution in full-color display. This is because the red (R), green (G), and blue (B) pixels are arranged in a plane, and therefore the number of pixels is always required to be tripled. In addition, the light transmitted through the color filter had a remarkable decrease in the amount of light. On the other hand, the three-panel system has no problem in resolution, but the optical system becomes complicated, and at the same time, it is difficult to reduce the size and cost because three panels are required. There is also one using two liquid crystal display bodies, but the projection image is dark due to the attenuation of the amount of light due to the light passing through the color filters, as in the case of the projection type display device composed of one liquid crystal display body. There was a drawback that

[Problems and Objectives to be Solved by the Invention]

In the above-mentioned conventional technology, there is a trade-off between high resolution, low cost, and miniaturization, and there are only extreme conditions. Therefore, the present invention solves such a problem, and an object of the present invention is to realize a projection type display device having a high resolution and a good luminance characteristic at a small size and a low price.

[Means for solving problems]

The projection display device of the present invention includes a first colored light, a second colored light, and a third colored light, each of which is a component of three primary colors.
And a color separation unit that separates the light emitted from the light source unit into a combined light of the first color light, the second color light, and a third color light. A first light modulator that modulates the third color light, a second light modulator that modulates the combined light, the third color light and the third light modulated by the first light modulator, In the projection display device, a color combining unit that combines the combined light modulated by the second light modulating unit and a projection lens that projects the light combined by the color combining unit onto a screen are provided. Of the light modulating means and the second light modulating means, only the second light modulating means is provided with a color filter.

[Work]

According to the above configuration of the present invention, downsizing and cost reduction can be promoted without significantly reducing resolution.

Example 1 FIG. 1 is a schematic view of a liquid crystal projection device used in the present invention.
The light from the light source using xenon or halogen is decomposed into the G component and the (R + B) component by the first dichroic mirror. The G component passes through the G liquid crystal cell 9 and the (R + B) component passes through the liquid crystal cell 8. After that, they are combined again by the dichroic mirror 3 and then projected onto the screen 7 by the projection lens 6.
You get a full-color image on top. Mirror here
4,5 are the ones that reflect the light flux to the car.

FIG. 2 shows the wavelength characteristic of the dichroic mirror used here. For example, of the white light incident on the dichroic mirror 2, only the G component passes, and the other components are reflected and guided to the left.

FIG. 3 shows a liquid crystal cell used here. (R +
The liquid crystal cell 8 for the component (B) has R and B pixels as in (A). The arrangement of R and B may be stripes, but the number of pixels of R and B is approximately 1: 1. The liquid crystal cell for G has G pixels on one surface as shown in (B), but even if there is no green color, the incident light has only the G component, and therefore a white type may be used. However, the amount of light transmitted through the liquid crystal cell (B) for the G component is about twice that of the liquid crystal cell (A) for the (R + B) component, and as a result, the brightness of the projected image on the screen is dramatically improved. However, the green color may be emphasized considerably. In this case, as shown in FIG. 1, the light amount adjusting plate 10 may be used to attenuate the G component light. The light quantity adjusting plate 10 may be a simple filter or a polarizing plate.

In the projection device according to the present invention, G
The component light and the (R + B) component light are combined to obtain a full-color image. Taking the NTSC system television signal as an example of the most general image, the luminance signal band, that is, the G component has a band of 3.58 MHz, while the R and B component video signal bands have a frequency of 1 MHz. It's all right. Therefore, using the fact that the human eye has the highest visibility in green and the wide bandwidth of the video signal, if the number of images in the liquid crystal cell containing only the G component is more than double that of R and B, the resolution is increased. Is dramatically improved. The present invention utilizes this effect.

FIG. 4 is a structural example of a liquid crystal cell for the (R + B) component used in the present invention, (A) showing a plan view and (B) showing a cross section. A color filter layer 19 is formed on the glass plate 15. This color filter layer is formed by dyeing an organic film with a dye, for example, and has red (R) and blue (B) layers in a plane. The lower glass 16 and the upper glass 15 are separated by a seal portion 17, and liquid crystal is sealed between them. In this figure, the R and B arrays of color filters are vertical stripes. Of course, horizontal stripes are also possible.

〔The invention's effect〕

As described above, in the present invention, for example, focusing on the fact that one color light is a monochromatic light, the color filter is provided only in the light modulation means for modulating the combined light. therefore,
In a projection display device using two liquid crystal displays, a high-resolution projection display device having a good luminance characteristic and a small size can be used.
It has become possible to achieve this at a low price.

[Brief description of drawings]

 FIG. 1 is a block diagram of a liquid crystal projection device of the present invention. FIG. 2 is a wavelength characteristic diagram of the dichroic mirror. 3A and 3B are structural views of the liquid crystal cell. (A) ... (B + R) component (B) ... G component FIG. 4 (A) is a plan view of a structural example of a liquid crystal cell. FIG. 4B is a cross-sectional view of a structural example of a liquid crystal cell.

Claims (1)

[Claims] 1. A light source section for emitting light composed of a first color light, a second color light, and a third color light, each of which is a component of three primary colors, and a light emitted from the light source section. A color separation means for separating the combined light of the first color light and the second color light and a third color light, a first light modulation means for modulating the third color light, A color for combining the second light modulating means for modulating the combined light, the third color light modulated by the first light modulating means, and the combined light modulated by the second light modulating means In a projection display device having a combining means and a projection lens for projecting the light combined by the color combining means onto a screen, the first light modulating means and the second light modulating means may be the first light modulating means. 2. A color filter is provided only for the light modulation means 2 Type display device.