JP2629616B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device such as a liquid crystal projector capable of obtaining a good image.

[0002]

2. Description of the Related Art A conventional projection type three-lens type liquid crystal projector has a configuration as shown in FIG. That is, a red projection lens 21, a green projection lens 22, and a blue projection lens 23 are linearly arranged, and a red LCD ( liquid crystal display ) 24 and a green LCD 25 are arranged behind these projection lenses 21, 22, and 23. And blue LCD 26 are arranged respectively, and behind these LCDs 24, 25 and 26, red LCD 26 is arranged .
A reflection mirror 27 , a green reflection mirror 28 and a blue reflection mirror 29 are arranged, and a light source 30 is arranged behind these reflection mirrors. At this time, the reflection mirrors 27 and 28 of each color
And 29 and the light source 30 are arranged on the same optical axis.

In the conventional liquid crystal projector having the above-described configuration, light generated from the light source 30 is reflected by reflection mirrors 27, 28, and 29 of respective colors and is incident on LCDs 24, 25, and 26 of respective colors. Are projected on a projection screen (not shown) through the projection lenses 21, 22 and 23 of the colors shown in FIG.

[0004]

In the conventional liquid crystal projector constructed and arranged as described above, the distance (optical path length) from the light source to the LCD ( liquid crystal display ) of each color is different. Since the light generated from the light source is not perfectly parallel light, if the optical path lengths are different, each L
There is a drawback that the distribution of light on the CD surface is different, and the image projected on the screen becomes uneven in color and brightness.

In order to equalize the optical path lengths, it is conceivable that light having a short optical path length is detoured (detoured) via a mirror and made incident on a liquid crystal display panel. In this case, the light is detoured via a mirror. As a result, the size increases and the space efficiency deteriorates.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device which has been made in view of the above circumstances and can provide a good image and does not deteriorate space efficiency.

[0007]

According to the present invention, in order to achieve the above object, light of a light source is separated into a plurality of colors, and the light is incident on a plurality of liquid crystal display panels, respectively. In a liquid crystal display device for displaying an image,
Means for reciprocating at least one of the colors on the same optical path between the light source and the liquid crystal display panel is provided, and the optical path length between the light source for each color and the liquid crystal display panel is substantially the same. It is characterized by doing.

According to the present invention, the light having a short optical path length from the light source to the liquid crystal display panel out of the plurality of divided light beams is reciprocated on the same optical path to increase the optical path length, thereby being divided into a plurality of light beams. The optical path length between the light source of each color and the liquid crystal display panel is made substantially the same.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the liquid crystal projector of the present invention. The liquid crystal projector of the present invention has three color projection lenses, namely, a red projection lens 1, a green projection lens 2,
A blue projection lens 3, a red LCD (liquid crystal display) 4, a green projection lens 2 behind the red projection lens 1;
, And a blue LCD 6 behind the blue projection lens 3. Behind these LCDs, a red reflection mirror 7, a green polarization beam splitter 10, and a blue polarization beam splitter 13 are provided, respectively.
Are arranged, and the red reflection mirror 7, the green polarization beam splitter 10 and the blue polarization beam splitter 13 are arranged on the same optical axis.

A green reflecting mirror 8 is provided between the red reflecting mirror 7 and the polarizing beam splitter 10 for green.
A blue reflection mirror 11 is provided between the green polarization beam splitter 10 and the blue polarization beam splitter 13.
Further, a green 1 / 4λ plate 9 and a red 1 / 4λ plate 16 are arranged in close contact with each other on both sides of the green reflection mirror 8, and similarly, a blue 1 / 4λ plate is placed on both sides of the blue reflection mirror 11. 1
2 and 1 / 4λ plates 15 for red and green are arranged in close contact with each other. Further, the blue polarization beam splitter 13
The light source 14 is arranged behind the.

In the liquid crystal projector of the present invention constructed as described above, white light generated from the light source 14 is transmitted by the blue polarization beam splitter 13 only with p-polarized light.
The p-polarized light passes through the 1 / 4.lambda. plate 12 for blue light and is reflected only by the blue reflection mirror 11 on the blue reflecting mirror 11, and is again reflected on the 1 / 4.lambda.
The light becomes s-polarized light via the λ plate 12, is reflected by the blue polarization beam splitter 13, and enters the blue LCD 6.

On the other hand, the red light and the green light pass through the blue reflecting mirror 11, pass through the red and green 1 / 4.lambda. Plates 15, return to p-polarized light, pass through the green polarizing beam splitter 10, and then pass through the green light. Only the green light is reflected by the green reflecting mirror 8 through the 1 / 4.lambda. Plate 9 for light, again converted into s-polarized light through the 1 / 4.lambda. Plate 9 for green, reflected by the polarizing beam splitter 10 for green, and incident on the LCD 5 for green. I do.
The red light passes through the green reflecting mirror 8 and then passes through the red 1 / 4λ plate 16 to return to p-polarized light again, is reflected by the red reflecting mirror 7 and enters the red LCD 4.

In this manner, the blue light, green light and red light incident on the blue LCD 6, the green LCD 5 and the red LCD 4, respectively, are projected onto the projection lens 3,
The image is projected onto a projection screen (not shown) via 2 and 1 to reproduce an image of a desired color.

According to the present invention, as shown in FIG. 1, the distance (a) from the reflection point of the blue polarization beam splitter 13 to the reflection point of the blue reflection mirror 11 and the reflection point of the blue reflection mirror 11 The distance (a) to the reflection point of the red reflection mirror 7 is made equal, and green reflection occurs at a distance (d) between each of the reflection point of the blue reflection mirror 11 and the reflection point of the red reflection mirror 7 at three equal intervals. The reflection points of the mirror 8 and the polarization beam splitter 10 for green are positioned.

Therefore, the light of each color is transmitted from the light source to the LCD of each color.
Are equal. That is, the distance from the light source 14 to the reflection point of the blue polarization beam splitter 13 is c, and the distance from each LCD to each reflection point of the red reflection mirror 7, the green polarization beam splitter 10, and the blue polarization beam splitter 13. Let b be the distance from the light source 14 to the blue LCD 6 to the blue light is c + 2a + b, and the distance from the green light from the light source 14 to the green LCD 5 is c + a + 3d (a) +
b = c + 2a + b, and the distance from the light source 14 to the red LCD 4 from the light source 14 is c + 2a + b,
The respective distances, that is, the optical path lengths are completely the same.

Further, by providing the green reflecting mirror 8 between the red reflecting mirror 7 and the green polarizing beam splitter 10, the space in the liquid crystal projector can be reduced.

[0017]

As described above, according to the present invention, a part of the light is reciprocated on the same optical path to increase the optical path length, so that the optical path between the light source of each of the plurality of divided colors and the liquid crystal display panel is obtained. Since the lengths are almost the same, the distribution of light on the LCD surface of each color becomes equal, so that it is possible to obtain a good image without unevenness in color and brightness, and to improve the space efficiency of the liquid crystal projector. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an example of a liquid crystal projector according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a conventional liquid crystal projector.

[Explanation of symbols]

 1 Projection lens for red 2 Projection lens for green 3 Projection lens for blue 4 LCD for red (LCD display) 5 LCD for green 6 LCD for blue 7 Red reflection mirror 8 Green reflection mirror 9 Blue 1 / 4λ plate 10 Polarization for green Beam splitter 11 Blue reflecting mirror 12 1 / 4λ plate for blue 13 Polarizing beam splitter 14 for blue light source 15 Red and green 1 / 4λ plate 16 1 / 4λ plate for red

Claims (1)

(57) [Claims] 1. A liquid crystal display device which separates light from a light source into a plurality of colors, makes the light incident on a plurality of liquid crystal display panels, and displays an image with light emitted from the liquid crystal display panels. A means for reciprocating at least one of the colors on the same optical path between the light source and the liquid crystal display panel. Display device.