JPH0749490A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To perfectly solve the light shielding part of a picture element or color filter even when the effect for solving the picture element dot of a liquid crystal display element is enhanced and extended, and provide an uniform and smooth display in which no unnatural pattern is confirmed by using a plurality of diffraction gratings in combination. CONSTITUTION:In a liquid crystal display device in which a liquid crystal display element having picture elements in matrix is combined with an optical low pass filter by a diffraction grating, the optical low pass filter 202 is formed by combining at least two kinds or more of diffraction gratings 203, 204. Further, the optical low pass filter 202 is formed of the diffraction gratings 203, 203 formed on both surfaces of one transparent base. The diffraction grating 203 is a secondary grating in which horizontal pitches and vertical pitches are mutually crossed at right angles, and its grating axis is inclined to the display screen of the liquid crystal display element. The diffraction grating 204 is a primary grating, and its grating axis is parallel to the vertical direction of the display screen of the liquid crystal display element.

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.

[0002]

2. Description of the Related Art Liquid crystal display devices, particularly active matrix liquid crystal display devices, use a conventional CRT because a display quality image comparable to that of a CRT can be obtained, the display device can be reduced in size and weight, and power consumption is low. It is used not only as a substitute for CRTs in various fields, but also in various fields. In particular, an active matrix liquid crystal display device using a polysilicon TFT as a switching element for driving a liquid crystal can make a driving IC on the same substrate and can form a liquid crystal display device having high density picture elements, which is small in size. It is used as a light valve for viewfinders and video projectors that require high-definition liquid crystal display devices. However, when it is used as a light valve for a viewfinder or a video projector, the display screen is magnified and observed by an optical system, so that a small picture element that cannot be discerned by the naked eye is magnified. When the magnification of enlargement is increased, the dots of the picture elements are confirmed, and the display quality of the image is significantly deteriorated, resulting in a so-called rough display. In order to prevent the dots of the picture element from being recognized even when enlarged, the picture element on the display screen may be further miniaturized, but the miniaturization of the picture element has a technical limit. Therefore, a liquid crystal display device has been proposed in which the dots of the picture elements are not conspicuous even if the enlargement ratio is increased by using an optical low-pass filter with a diffraction grating. An optical low-pass filter using a one-dimensional diffraction grating separates picture elements in the horizontal or vertical direction, and an optical low-pass filter using a two-dimensional diffraction grating separates picture elements in the horizontal direction and the vertical direction, respectively, thereby eliminating picture element dots. In the conventional liquid crystal display device, as shown in the schematic view of FIG. 3, the optical low-pass filter has only one transparent low-pass filter having a one-dimensional or two-dimensional diffraction grating formed on one surface thereof, which is disposed in front of the liquid crystal display element. It was

[0003]

However, in the optical low pass filter used in the conventional liquid crystal display device, the separated picture elements are the picture elements of the same size as the original picture element, and thus the front surface of the display screen. Could not be made into a uniform state. Therefore, there is a problem in that a pattern is generated on the display screen even if the picture element disappears and becomes inconspicuous. Therefore, the present invention solves such a problem, and an object of the present invention is to obtain a liquid crystal display device which provides a high-quality display.

[0004]

A liquid crystal display device according to the present invention is a liquid crystal display device comprising a liquid crystal display device having picture elements in a matrix and an optical low pass filter formed by a diffraction grating, wherein the optical low pass filter is It is characterized by combining at least two kinds of diffraction gratings. Further, the optical low-pass filter is characterized in that a diffraction grating is formed on both surfaces of one transparent substrate.

[0005]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic view of a liquid crystal display device in a first embodiment of the liquid crystal display device of the present invention.
The liquid crystal display element 101 of the embodiment is a color liquid crystal display element for a viewfinder using a polysilicon TFT having a diagonal of 0.7 inches and a triangle arrangement of about 100,000 picture elements. The size of the picture element of this liquid crystal display element is vertical 2
6 μm x 16 μm width, with a pixel pitch of 38 μ in the horizontal direction
m and 46 μm in the vertical direction. The optical low-pass filter 102 has a diffraction grating formed by photo-etching a photosensitive resin on a glass substrate having a thickness of 0.6 mm. The diffraction grating of the optical low-pass filter 102 is a two-dimensional grating in which both the horizontal pitch and the vertical pitch are 20.4 μm and are orthogonal to each other, and the grating axis is tilted by 20.0 ° with respect to the display screen of the liquid crystal display element. ing. The optical low pass filter 103 has a diffraction grating formed by photo-etching a photosensitive resin on a glass substrate having a thickness of 0.6 mm. The diffraction grating of the optical low-pass filter 103 has a grating pitch of 7
It is a one-dimensional lattice of 2.4 μm, and its lattice axis is parallel to the vertical direction of the display screen of the liquid crystal display element. The distance between the liquid crystal display element 101 and the diffraction grating surface of the optical low-pass filter 102 is set to 0.20 mm. The distance between the diffraction grating surfaces of the optical low pass filter 102 and the optical low pass filter 103 is set to 0.20 mm. Even when the image thus obtained on the liquid crystal display device was enlarged, the light-shielding portions of the picture elements and color filters were completely eliminated, and a uniform and smooth display without unnatural patterns was obtained.

(Embodiment 2) FIG. 2 is a schematic view of a liquid crystal display device according to a second embodiment of the liquid crystal display device of the present invention.
The liquid crystal display element 201 of the embodiment is a color liquid crystal display element for a viewfinder using a polysilicon TFT having a diagonal of 0.7 inch and a triangle arrangement of about 100,000 picture elements. The size of the picture element of this liquid crystal display element is vertical 2
6 μm x 16 μm width, with a pixel pitch of 38 μ in the horizontal direction
m and 46 μm in the vertical direction. The optical low-pass filter 202 is made of acrylic resin by injection molding and has a thickness of 0.8 mm. The optical low-pass filter 202 has a diffraction grating 203 formed on the surface facing the liquid crystal display element 201 and a diffraction grating 204 formed on the back surface thereof. The diffraction grating 203 is a two-dimensional grating in which the horizontal pitch and the vertical pitch are both 20.4 μm and are orthogonal to each other, and the grating axis is tilted by 20.0 ° with respect to the display screen of the liquid crystal display element. The diffraction grating 204 has a grating pitch of 7
It is a one-dimensional lattice of 2.4 μm, and its lattice axis is parallel to the vertical direction of the display screen of the liquid crystal display element. The distance between the liquid crystal display element 201 and the diffraction grating 203 is set to 0.20 mm. Even when the image thus obtained on the liquid crystal display device was enlarged, the light-shielding portions of the picture elements and color filters were completely eliminated, and a uniform and smooth display without unnatural patterns was obtained.

[0008]

As described above, according to the present invention, by using a plurality of diffraction gratings in combination, the effect of eliminating the picture element dots of the liquid crystal display device is enhanced and the light-shielding portion of the picture element or the color filter remains It was completely eliminated, and a uniform and smooth display was obtained with no unnatural patterns.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a schematic view of a liquid crystal display device using a conventional diffraction grating.

[Explanation of symbols]

 101 liquid crystal display element 102 optical low-pass filter 103 optical low-pass filter 104 light traveling direction 201 liquid crystal display element 202 optical low-pass filter 203 diffraction grating 204 diffraction grating 205 light traveling direction 301 liquid crystal display element 302 diffraction grating 303 light traveling direction

Claims (2)

[Claims] 1. A liquid crystal display device comprising a liquid crystal display element having picture elements in a matrix and an optical low-pass filter formed by a diffraction grating, wherein the optical low-pass filter is formed by combining at least two kinds of diffraction gratings. Liquid crystal display device characterized by. 2. The liquid crystal display device according to claim 1, wherein the optical low-pass filter has a diffraction grating formed on both surfaces of one transparent substrate.