JPH0545725A - Projection type liquid crystal display device - Google Patents

Abstract

(57) [Summary] [Object] In a liquid crystal display device equipped with a lens array, a projection-type liquid crystal display device is provided with high brightness by creating a light ray angle distribution advantageous to the lens array. [Structure] A liquid crystal light valve 103 in which a lens array 104 is integrated is tilted with respect to an optical axis, and a liquid crystal light valve 103, a projection lens 105, and a projection screen 10 are provided.
The three elements of 6 are arranged so as to satisfy Scheimpflug's law. With this arrangement, the light rays 112 and 113 are incident on the lens array 104 at an angle that is advantageous for the condensing function of the lens array 104. [Effect] It is possible to increase the amount of light transmitted through the pixel opening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type liquid crystal display device.

[0002]

2. Description of the Related Art One of the problems to be solved by a projection type liquid crystal display device is that the brightness of a projected image is low. In order to solve the above problems, it has been proposed to form a lens array body in a liquid crystal display element and collect incident light to the liquid crystal pixel aperture to improve the brightness. (For example, JP-A-57-157
215, JP-A-60-165624).

[0003]

However, since the proposals found in the prior art hardly consider the characteristics of a series of optical systems including a light source, it is hard to say that any of them is effective. The reason will be described with reference to FIGS. In the conventional projection type liquid crystal display device, it is necessary to use an optical system as shown in FIG. 5A in consideration of the angle of view of the projection lens and the size of the lamp. Here, 501 is a lamp, 502 is a condenser lens, 503 is a liquid crystal light valve, 50
Reference numeral 4 is a lens array, 505 is a projection lens, and 506 is a projection screen. The illumination system in this optical system is shown in FIG.
It shows in (B). In this illumination system, the liquid crystal light valve 503
Most of the light beams incident on the light beams are as shown by 507 and 508. In such an illumination system, the incident angle distribution of the incident light on the light incident surface of the lens array 504 has a distribution as shown in FIG. 7. In this figure,
The vertical axis represents the light intensity (arbitrary unit), and the horizontal axis represents the ray incident angle with respect to the lens array normal. Also,
The + angle corresponds to the direction from bottom to top in FIG. 5, and-is the opposite. The strongest angle component of the normal light intensity (mountain portion in the curve of FIG. 7) is ± 5 to 8
Often distributed in °. Next, let us consider the configuration of the lens array with reference to FIG. The individual lens elements 605 that normally form the lens array and the pixel openings 6
The thickness of the counter substrate 604 existing between 10 is 0.3 to 1
mm, the size of the pixel opening 610 is 50 μm × 50
μm, pitch about 100 μm × 100 μm. The angle that the pupil of the projection lens forms with the pixel aperture is ±
It is about 6 to 9 °. Considering the above three points, it is necessary to form a lens body having an F number of about 6 to 8 and a long focal length as the lens element 605. An example is given to explain what kind of condensing property such a lens has.
As an example, when the focal length of the lens element 605 in the counter substrate is 0.4 mm, the incident angle (incident angle with respect to the normal to the lens array) is about −3.5 ° to + 3.5 °.
The light ray 607 in the range (hereinafter, referred to as a low angle component) can be focused on the pixel opening 610. The light rays 608 (hereinafter, referred to as the middle angle component) having a larger range of about −3.5 to −9 ° and + 3.5 ° to + 9 ° cannot be focused on the pixel opening portion, and the light shield portion. The light is focused on 603. Therefore, the light rays of the medium angle component cannot be used for image projection. About -9, which is larger than that
Rays 609 in the range of ° to -12 °, +9 ° to +12 °
(Hereinafter, referred to as a high angle component) can be focused on the pixel opening 611 adjacent to the pixel opening 610 that focused the low angle component. Therefore, in order to maximize the effect of the lens array that improves the brightness of the projected image, it is required that the incident angle distribution of the light rays that enter the lens array be concentrated in the low angle component and the high angle component. To be done. Applying the angle range described here to FIG.
The angle range indicated by 01 corresponds to the low angle component, the angle range indicated by 702 corresponds to the middle angle component, and the angle range indicated by 703 corresponds to the high angle component. As is clear from this, the lens array cannot utilize the angle component of the strongest light intensity,
Therefore, there is a problem that the effect cannot be maximized. Here, the problem was shown by taking one lens array design value as an example, but there is not a large margin in the design of the lens array due to the above-mentioned restrictions on the configuration of the liquid crystal light valve. Even if there is, the basic problem remains the same. The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical system in which a lens array body can exert the maximum effect, and to increase the brightness of a projection type liquid crystal display device. Is to measure.

[0004]

In order to solve the above-mentioned problems, a projection type liquid crystal display device of the present invention is provided with a lens array having a condensing function corresponding to the liquid crystal pixels of a liquid crystal light valve. And the liquid crystal light valve is arranged obliquely with respect to the optical axis of the projection optical system, and the arrangement of the projection screen, the projection lens, and the liquid crystal light valve satisfies the Scheimpflug's law. It is characterized by doing.

[0005]

【Example】

Example 1 An outline of an optical system of a projection type liquid crystal display device of the present invention is shown in FIG. The optical system of the present invention is characterized in that the liquid crystal light valve 103 and the lens array 104 have an optical axis 114.
Liquid crystal light valve 1 that is arranged diagonally to
03, the projection lens 105, and the projection screen 106 are arranged so as to satisfy Scheimpflug's law. The reason why the liquid crystal light valve 103 is obliquely arranged with respect to the optical axis will be described. As shown in FIG. 1 (B), most of the luminous flux from the lamp 101 is such as 112 and 113 as described in the prior art. At this time, the light ray incident angle on the light ray incident surface of the lens array 104 is as shown in FIG. 3 because the light ray incident surface is inclined with respect to the optical axis 114. The angle regions 301, 302 and 303 are respectively 701 and 701 in FIG.
It corresponds to 702 and 703. Therefore, most of the strong angular component can pass through the pixel opening. This will be described with reference to FIG. 2. The light ray 208 corresponding to the light flux 113 in FIG. 1 is condensed by the lens element 205 and passes through the pixel opening 209, and the light ray 207 corresponding to the light flux 112 in FIG. It is condensed by the lens element 205 and passes through the pixel opening 210 adjacent to the pixel opening 209. Therefore, more light rays can pass through the pixel openings as compared with the conventional technique, so that the brightness of the projected image can be increased. Next, the liquid crystal light valve, projection lens,
The reason why the layout of the projection screen is arranged so as to satisfy the Scheimpflug's law is that the liquid crystal light valve is tilted with respect to the optical axis, and therefore this layout must be taken. by. In this arrangement, in FIG. 1, the angle between the normal line of the liquid crystal light valve 103 and the optical axis 114 is θ, the angle between the normal line of the projection screen 106 and the optical axis 114 is θ ′, the principal point of the projection lens 105, When the distances between the center of the liquid crystal light valve and the center of the projection screen are S and S ′ (where S ′ is negative), the following formulas are used. tan θ ′ = m · tan θ where m = S ′ / S Specific design values of this embodiment are shown. Of the luminous fluxes from the illumination optical system used, the angle of the strongest light ray with respect to the optical axis was estimated to be ± 5.2 °. The opposite substrate of the liquid crystal light valve used was a refractive index of 1.54 and a thickness of 400 μm.
m, the width of the pixel opening is 30 μm, and the pixel pitch is 56 μm
Is. Further, the projection magnification m = −42.3. Therefore, the lens element of the lens array is a lenticular lens having a width of 56 μm and a focal length of 260 μm, and the liquid crystal light valve is tilted by 5.2 ° in the direction indicated by θ in FIG. Also, the projection screen was tilted by 75.4 ° in the direction indicated by θ ′ in FIG. As a result, 1.6 when the lens array is not mounted
It was possible to obtain 1.32 times the projected image brightness when the lens array is mounted but the configuration of the present invention is not adopted.

(Example 2) Using the optical system used in Example 1, a projection type liquid crystal display unit shown in FIG. 4 was prepared. In this projection type liquid crystal display device, the liquid crystal light valve 406 and the projection screen 402 are tilted horizontally with respect to the viewer 409. The positional relationship among the projection screen, the projection type liquid crystal display unit, and the viewer is as shown in (B) when viewed in the horizontal direction. As you can see,
Since there is no projection type liquid crystal display unit between the viewer and the projection screen, the viewing condition is extremely good.

[0007]

As described above, according to the present invention, in the projection type liquid crystal display device equipped with the lens array, the liquid crystal light valve is arranged obliquely with respect to the optical axis, and the liquid crystal light valve, the projection lens, By arranging the three elements of the projection screen so as to satisfy the Scheimpflug's law, the light beam can be efficiently guided to the pixel aperture. Therefore, it is possible to improve the brightness of the projection type liquid crystal display device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of Embodiment 1 of the present invention.

FIG. 3 is an explanatory diagram of Embodiment 1 of the present invention.

FIG. 4 is an explanatory diagram of a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional technique.

FIG. 6 is an explanatory diagram of a conventional technique.

FIG. 7 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

101 Lamp 102 Condenser Lens 103 Liquid Crystal Light Valve 104 Lens Array 105 Projection Lens 106 Projection Screen 107 Angle Between Normal Line and Optical Axis of Liquid Crystal Light Valve 108 Angle Between Normal Line and Optical Axis of Projection Screen 109 Liquid Crystal Light Valve Surface, Projection Line of intersection between screen surface and main plane of projection lens 110 Distance between liquid crystal light valve and main plane of projection lens 111 Distance between projection screen and main plane of projection lens 112 Light flux 113 Light flux 114 Optical axis 201 Thin film transistor substrate 202 Thin film transistor 203 Light shielding portion 204 Counter substrate 205 Lens element 206 Lens array substrate 207 Light ray corresponding to light flux 112 208 Light ray corresponding to light flux 113 209 Pixel opening 210 Pixel opening 211 Optical axis 212 Normal line and optical axis of liquid crystal light valve Angle 301 Angle area 302 Angle area 303 Angle area 401 Projection liquid crystal display unit 402 Projection screen 403 Projection lens 404 Mirror 405 Dichroic mirror 406 Liquid crystal light valve with lens array 407 Condenser lens 408 Lamp 409 Spectator 501 Lamp 502 Condenser lens 503 Liquid crystal light valve 504 Lens array 505 Projection lens 506 Projection screen 507 Light flux 508 Light flux 509 Optical axis 601 Thin film transistor substrate 602 Thin film transistor 603 Light-shielding portion 604 Opposing substrate 605 Lens element 606 Lens array substrate 607 Low angle component light beam 608 Medium angle component light beam 609 Rays of high-angle component 610 Pixel aperture 611 Pixel aperture 612 Optical axis 701 Angular region 7 2 angle area 703 angle area

Claims (1)

[Claims] 1. A lens array having a condensing function is provided and integrated corresponding to liquid crystal pixels of a liquid crystal light valve, and the liquid crystal light valve is oblique to an optical axis of a projection optical system. A projection-type liquid crystal display device, wherein the projection screen, the projection lens, and the liquid crystal light valve are arranged, and the arrangement of the three elements satisfies the Scheimpflug's law.