JPH0949995A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display device capable of reducing the influence of astigmatism with a compact constitution at a low cost. SOLUTION: A white light beam from a light source 1 is separated into the light beams of three primary colors by color separation dichroic mirrors 4 and 5 separating the output light beam from the light source into three primary color components in accordance with a wavelength region, and liquid crystal panels 8, 14 and 16 corresponding to the respective light beams of primary colors are irradiated with the light beams of three primary colors. The panels 8, 14 and 16 transmit the irradiating light beams after modulating their intensity in accordance with a video signal. The light beam G and the light beam R out of the transmitted light beams whose intensity is modulated are composited by a color compositing dichroic mirror 9. The light beam B is reflected by a total reflection mirror 17 having a cylindrical recessed surface, and the reflected light beam B is composited with the above composited light beam by a color compositing dichroic mirror 10 and projected from a projection lens 11. By such constitution, the deviation of convergence caused by the transverse chromatic aberration of the projection lens is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used in, for example, a liquid crystal projector, and more particularly to a liquid crystal display device.
The present invention relates to a liquid crystal display device in which pixels of each liquid crystal panel for GB are matched on a projected image.

[0002]

2. Description of the Related Art Conventionally, as a liquid crystal display device, a projection type liquid crystal display device capable of displaying an image on a large screen has been known. In this projection type liquid crystal display device, the light emitted from the light source is applied to the liquid crystal panel, and an optical image corresponding to the video signal is formed on the liquid crystal panel so that the intensity of the applied light is modulated and transmitted. It is configured so that transmitted light is incident on a projection lens and the optical image is enlarged and projected on a screen.

In such a projection type liquid crystal display device,
When displaying a full-color image, the light from the light source is U
After passing through the V / IR cut filter, each color of primary color light is separated by a color separation dichroic mirror.

The separated primary color lights are made incident on three liquid crystal panels corresponding to the respective RGB primary color lights, intensity-modulated by an optical image corresponding to a video signal, and then each color is synthesized by a color combining dichroic mirror. Primary color light is synthesized,
This combined light is enlarged and displayed on the screen via the projection lens.

When a full-color image is projected by color-separating and synthesizing the RGB three primary colors in this way, in order to obtain a good image quality, the pixels of each liquid crystal panel for RGB should be matched on the projected image. That is, it is necessary to match the RGB convergence deviations. When the RGB convergence does not match, the image is blurred (resolution is deteriorated), and a color shift is caused particularly in the contour portion, which significantly deteriorates the image.

As a cause of this convergence deviation in the optical system, it is conceivable that there is convergence deviation caused by lateral chromatic aberration of the projection lens.

[0007]

Therefore, as a technique for correcting the lateral chromatic aberration of the projection lens, Japanese Patent Laid-Open No. 6-18 has been proposed.
The technique disclosed in Japanese Patent No. 840 has been proposed.

The technique for correcting the chromatic aberration of magnification will be described below with reference to FIG.

In FIG. 8, a light beam emitted from a light source 1 and converged in one direction by a reflector 2 passes through a filter 3 and is then converted into primary color lights by color separation dichroic mirrors 4 and 5 and a total reflection mirror 6. To be separated.

The separated primary color lights are incident on the three liquid crystal panels 8, 14 and 16 respectively corresponding to the RGB primary color lights, intensity-modulated by an optical image corresponding to a video signal, and then color combination is performed. The primary color lights are combined by the dichroic mirrors 9 and 10 and the total reflection mirror 17.

Here, the total reflection mirror 17 has an appropriate concentric circular curvature in a convex or concave shape, and the total reflection mirror 17 causes RGB due to lateral chromatic aberration of the projection lens.
Correct the convergence gap between them.

However, this curvature is several tens to several hundreds of meters, and it is difficult and expensive to manufacture a total reflection mirror having such a curvature, which is not suitable for practical use.

Also, due to the fact that the dichroic mirrors are arranged asymmetrically with respect to the optical axis, astigmatism occurs when light passes through the dichroic mirrors.

As a technique for correcting astigmatism due to the asymmetrical arrangement of the dichroic mirrors on the optical axis, Japanese Patent Laid-Open No. 6-1 is known.
Japanese Patent No. 8840 has been proposed.

A technique for correcting astigmatism due to the asymmetrical arrangement of the dichroic mirror optical axes will be described below with reference to FIG.

In FIG. 9, each liquid crystal panel 8, 14, 1
The color combining dichroic mirrors 9 and 10 arranged in the light flux passing through 6 are wedge-shaped.
0 adjusts the level of astigmatism of each light flux to a low value equivalent to each other.

However, in order to form at least one of the color combining dichroic mirrors 9 and 10 into a wedge shape, a complicated and numerous manufacturing process is required as in the case of the prism, which results in high cost and low cost for consumer equipment. It has the drawback of not being suitable.

The liquid crystal display device of the present invention has been made in view of the above-mentioned drawbacks, and an object thereof is to obtain a liquid crystal display device which is inexpensive and has a small structure and which reduces the influence of astigmatism.

[0019]

According to the present invention, there is provided a light source which emits white light, a color separation means which separates output light of the light source into a plurality of color components according to a wavelength region, and a video signal. A plurality of liquid crystal panels which form an optical image and are irradiated with the output light of the color components from the color separation means, intensity-modulate the irradiation light and transmit the light, and one transmitted light of each color component from each liquid crystal panel. And a projection lens for receiving the output light from the color synthesizing means and projecting the optical image on a screen. The color synthesizing means includes a dichroic mirror and a reflecting mirror, and the dichroic mirror or At least one of the reflecting mirrors has a cylindrical convex or concave surface, and chromatic aberration of magnification of the projection lens or astigmatism generated by passing through the dichroic mirror A liquid crystal display device and corrects.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid crystal display device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the liquid crystal display device of the present invention.

FIG. 2 shows a lateral chromatic aberration curve of the projection lens 11 in the first embodiment.

The feature of the first embodiment is that the total reflection mirror 17 has an appropriate curvature of a cylindrical convex or concave surface so that RGB due to lateral chromatic aberration of the projection lens can be obtained.
This is a point to correct the convergence deviation between them.

In this embodiment, as shown in FIG. 2, a total reflection mirror 17 having a cylindrical convex or concave surface having an appropriate curvature is used to correct the magnification chromatic aberration characteristic of the B signal. There is.

In FIG. 1, the luminous flux emitted from the light source 1 and converged in one direction by the reflector 2 is cut into heat rays and ultraviolet rays by passing through the filter 3, and further, the G reflection dichroic mirror 4 and the R reflection dichroic. The light is split into R, G, and B primary colors by the mirror 5.

On the optical axis extension line of the reflector 2, a filter 3, a G reflection dichroic mirror 4, an R reflection dichroic mirror 5, a B condenser lens 15 and a B are arranged in this order.
A liquid crystal panel 16 and a total reflection mirror 17 are arranged. By giving the total reflection mirror 17 an appropriate curvature of a cylindrical convex or concave surface, the convergence deviation between RGB due to the lateral chromatic aberration of the projection lens is corrected.

The filter 3 cuts heat rays (infrared rays and far infrared rays) and ultraviolet rays of the light emitted from the light source 1 and transmits so-called visible rays.

The G reflection dichroic mirror 4 is arranged, for example, at an angle of 45 ° with respect to the optical axis extension line of the reflector 2, and only the G component (green component) of this visible light is placed on the optical axis extension line of the reflector 2. On the other hand, it is configured to reflect in a direction at a right angle, and to transmit other R component (red component) and B component (blue component).

On the optical axis of the reflected light reflected by the G reflecting dichroic mirror 4, a reflecting mirror 6 is arranged, for example, at an angle of 45 ° with respect to the optical axis, and the G component reflected by the reflecting mirror 4 is The R component (red component) and the B component (blue component) transmitted through the G reflection dichroic mirror 4 travel in parallel.

On the reflection optical axis of the reflection mirror 6, a G condenser lens 7, a G liquid crystal panel 8, an R reflection dichroic mirror 9, and an RG reflection dichroic mirror 1 are provided.
0, a projection lens 11 and a screen 12 are arranged.

The R reflection dichroic mirror 5 is arranged, for example, at an angle of 45 ° with respect to the optical axis extension line of the reflector 2, and only the R component of the light transmitted through the G reflection dichroic mirror 4 is reflected by the optical axis of the reflector 2. It is configured to reflect in a direction perpendicular to the extension line and transmit the B component.

A condenser lens 13 for R system and a liquid crystal panel 14 for R system are arranged on the reflection optical axis of the R reflection dichroic mirror 5, and the reflection light of the R reflection dichroic mirror 5 and the reflection optical axis of the reflection mirror 6 are arranged. The optical image of the G component transmitted through the R reflection dichroic mirror 9 and the optical image of the R component reflected thereby are combined at the intersection of
It is directed toward the reflection dichroic mirror 10, the projection lens 11 and the screen 12.

The total reflection mirror 17 is arranged, for example, at an angle of 45 ° with respect to the optical axis extension line of the reflector 2, passes through the G reflection dichroic mirror 4 and the R reflection dichroic mirror 5, and passes through the B condenser lenses 15 and B. Is transmitted through the liquid crystal panel 16 for B and the optical image of the B component formed by the liquid crystal panel 16 for B is drawn to the optical axis extension line of the reflector 2.
The RG reflection dichroic mirror 10 is reflected at right angles.

The plate thickness of the total reflection mirror 17 is 1.8 m.
It is designed to m.

Here, the total reflection mirror 17 is a leaf spring 17
It has a cylindrical concave surface formed by A and 17B.

The structure of the total reflection mirror 17 will be described below with reference to FIGS. 3 and 4.

3A and 3B are views showing the leaf springs 17A and 17B. FIG. 3A is a plan view of the leaf spring, and FIG. 3B is a side view.

FIG. 4 is an assembly diagram for mounting the leaf springs 17A and 17B on the total reflection mirror 17.

In FIG. 3, the leaf springs 17A and 17B are
It is made of an elastic stainless material (SUS304CSP) and has a thickness of 0.3 mm and a width of 5 mm. Then, the leaf springs 17A and 17B have folding pieces 17A1 and 17B1 for mounting in the peripheral portion,
The tip has guide portions 17A2 and 17B2 for guiding. Further, the central portions 17A3, 1 of the leaf springs 17A, 17B are
7B3 has a curve with a curvature of 115 m, and the amount of deflection is 3 mm.

The leaf springs 17A, 17 having the above structure
As shown in FIG. 4, B is attached to the peripheral portion of the total reflection mirror 17, which is outside the reflection of the luminous flux. As a result, the leaf spring 1
By mounting 7A and 17B, the total reflection mirror 17 having a plate thickness of 1.8 mm is formed with a cylindrical concave surface having a curvature of about 60 m.

When an image from a liquid crystal display device using the total reflection mirror 17 having a cylindrical concave surface configured as described above is projected on the screen 12 by the projection lens 11, FIG.
As shown in, the amount of convergence deviation between GBs in the peripheral portion is corrected to about one half of the conventional one.

FIG. 5 is a diagram for explaining the image shift on the screen by the liquid crystal display device of the present invention, and FIG. 6 is for explaining the image shift on the screen by the conventional liquid crystal display device. FIG.

Further, by providing the dichroic mirror 9 with an appropriate convex or concave cylindrical curvature, it is possible to correct the convergence deviation between R and G due to the lateral chromatic aberration of the projection lens.

Apart from this, conventionally, there has been a problem of astigmatism due to the fact that the dichroic mirrors are arranged asymmetrically with respect to the optical axis.

Since this astigmatism is generated in proportion to the thickness of the dichroic mirror, it is necessary to reduce the thickness of the mirror in order to reduce its influence, but at least it is necessary to ensure the plane accuracy. A plate thickness of about 1 to 1.5 mm is required. As a result, astigmatism occurs, and the vertical stripes and horizontal stripes are focused at different positions on the screen, and the vertical stripes and horizontal stripes must be focused in the middle. As a result, flare and the like occurred, leading to a reduction in resolution.

However, the above-mentioned drawbacks could not be solved in the first embodiment.

A second embodiment of the liquid crystal display device of the present invention which solves the above-mentioned drawbacks will be described.

FIG. 7 differs from the first embodiment in that, in addition to the total reflection mirror 17, the color combining dichroic mirrors 9 and 1 are provided.
0 is also the point where a cylindrical convex or concave curve is formed.

This curve is formed by mounting the leaf springs 9A and 9B and the leaf springs 10A and 10B on the peripheral portion outside the range where the light flux is reflected or transmitted, like the total reflection mirror 17.

As described above, the astigmatism due to the asymmetrical optical axis arrangement of the dichroic mirrors can be corrected by giving the color combining dichroic mirrors 9 and 10 an appropriate curvature of the cylindrical convex or concave surfaces.

As a result of simulating a liquid crystal display device equipped with a 1.3-inch liquid crystal panel, the total reflection mirror 17 has a curvature of 18 m, the dichroic mirror 9 has a curvature of 18 m, and the dichroic mirror 10 has a curvature of 150 m.
By forming a cylindrical convex or concave surface of m, astigmatism can be corrected small at the screen center of the screen.

Further, in the liquid crystal display device constructed as described above, as shown in FIG. 10, the maximum values of the horizontal and vertical MTFs are substantially the same in the central portion of the screen. Also in the prototype experiment, it was confirmed that the focus positions of the vertical stripes and the horizontal stripes substantially coincided with each other at the center of the screen.

Incidentally, FIG. 10 shows the MTF (Modulatio).
FIG. 10A is an MTF simulation of the central part of the screen in the conventional liquid crystal display device, and FIG. 10B is an MTF simulation of the central part of the screen in the liquid crystal display device of the present invention.

In this embodiment, the aspect ratio is
Although the simulation was performed on the image with the aspect ratio of 4: 3, the effect can be obtained even with the image with the aspect ratio of 16: 9.

[0055]

EFFECTS OF THE INVENTION It is possible to give a mirror an appropriate curvature of a cylindrical convex or concave surface by a simple structure in which leaf springs are attached to both ends of the total reflection mirror, and RGB between RGB due to lateral chromatic aberration of the projection lens can be obtained. It is possible to correct the convergence deviation.

Further, by making at least one of the dichroic mirrors have an appropriate curvature of a convex or concave cylindrical shape, the astigmatism of the light beam passing through the dichroic mirror can be corrected to a small value, and the astigmatism between RGB can be corrected. The difference can be reduced, and a high-definition liquid crystal panel can provide high image quality for large-screen projection.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a liquid crystal display device of the present invention.

FIG. 2 shows a lateral chromatic aberration curve of the projection lens in the first example.

FIG. 3 is a diagram showing leaf springs 17A and 17B.

FIG. 4 is an assembly view for mounting the leaf springs 17A and 17B on the total reflection mirror 17.

FIG. 5 is a diagram for explaining an image shift on a screen by the liquid crystal display device of the present invention.

FIG. 6 is a diagram for explaining an image shift on a screen by a conventional liquid crystal display device.

FIG. 7 is a configuration diagram for correcting astigmatism due to transmission of a dichroic mirror according to the present invention.

FIG. 8 is a block diagram of a conventional liquid crystal display device.

FIG. 9 is a block diagram of a conventional liquid crystal display device.

FIG. 10 is an MTF simulation diagram of the present invention.

[Explanation of symbols]

 1 Light Source 4 G Reflective Dichroic Mirror 5 R Reflective Dichroic Mirror 6 Reflective Mirror 7 G Condenser Lens 8 G Liquid Crystal Panel 9 R Reflective Dichroic Mirror 10 RG Reflective Dichroic Mirror 11 Projection Lens 12 Screen 13 R Condenser Lens 14 R Liquid Crystal Panel 15 B condenser lens 16 B liquid crystal panel 17 Total reflection mirror 17A leaf spring 17B leaf spring

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[Procedure amendment]

[Submission date] September 11, 1995

[Procedure amendment 1]

[Document name to be amended] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction contents]

FIG. 7

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroki Kiba 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A light source that emits white light, a color separation unit that separates the output light of the light source into a reciprocal number of color components according to a wavelength region, and an optical image corresponding to a video signal is formed to form the color separation. A plurality of liquid crystal panels that are irradiated with the output light of the color components from the means, modulate the intensity of the emitted light, and transmit the light; and a color combining means that combines the transmitted light of the respective color components from the liquid crystal panels into one. A projection lens for receiving the output light from the color synthesizing means and projecting the optical image on a screen is provided, and the color synthesizing means includes a dichroic mirror and a reflecting mirror, and at least one of the dichroic mirror or the reflecting mirror is a cylinder. It is characterized in that it has a convex or concave shape and corrects chromatic aberration of magnification of the projection lens or astigmatism caused by transmission through a dichroic mirror. Liquid crystal display device. 2. A leaf spring is attached to both ends of the dichroic mirror or the reflecting mirror, and the reflecting surface of the dichroic mirror or the reflecting mirror is formed into a convex or concave cylindrical shape by the leaf spring. 1. The liquid crystal display device according to 1.