JP2000047202A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device which is enhanced in contrast and luminance and is low in production cost. SOLUTION: The reflection type liquid crystal display device 1 is constituted by bonding one member which is formed by sequentially laminating electrodes 5 having light reflectivity and an alignment layer 7 on a rough surface 2a subjected to a sandblasting treatment of a glass substrate 2 and another member which is formed with color filters 10, an over-coating layer 12, transparent, electrodes 13 and an alignment layer 14 on a glass substrate 3 via a liquid crystal layer 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used for large and high-definition monitors in addition to small or medium-sized portable information terminals and notebook computers. Furthermore, in a reflective liquid crystal display device that does not use a backlight, a thin,
Excellent in light weight and low power consumption.

[0003] However, in order to obtain a bright display without using a backlight, it is necessary to emit light with a wide scattering angle with respect to incident light from all angles.

In view of the above, there have been proposed techniques for providing a scattering reflector as described in (1) and (2) below. (1) A reflector provided in a liquid crystal display device is treated so that its surface becomes uneven (Japanese Patent Laid-Open No. 4-75022).
issue). (2) A mirror reflector is provided on the liquid crystal display device,
Further, a scattering film is disposed on the front surface of the apparatus (Japanese Unexamined Patent Application Publication No.
-201802).

[0005]

[Problems to be solved by the invention]
In the technique of (1), it is difficult to perform a treatment so that a uniform uneven surface is formed over the entire surface of the reflector, and furthermore, the uneven surface occurs between the reflectors of each product.
On the other hand, it has been proposed to use a photolithography technique in which a photosensitive resin is coated on a glass substrate, developed after exposure, and an uneven surface is formed (Japanese Patent Laid-Open No. 4-24).
No. 3226), the use of the photolithography technique increases the number of steps, increases the production cost, and does not yet provide a satisfactory uniform uneven surface. Also,
In the technique (2), the contrast is reduced due to back scattering of incident light.

In view of the above circumstances, the inventor of the present invention has intensively studied the technique (1). As a result, a uniform uneven surface can be obtained by sandblasting the substrate and further covering the entire surface of the reflector. Was found.

The present invention has been accomplished based on the above findings, and an object of the present invention is to provide a reflection type liquid crystal display device having enhanced contrast and brightness. Another object of the present invention is to provide a reflective liquid crystal display device in which a uniform uneven surface can be easily produced by using a sandblasting process, thereby reducing the production cost.

[0008]

According to the reflection type liquid crystal display device of the present invention, one main surface of a substrate is subjected to sandblast treatment, and an electrode film having light reflectivity and an alignment layer are sequentially laminated on the one main surface. And the other member formed by sequentially laminating a transparent electrode and an alignment layer on a transparent substrate, and interposing a nematic liquid crystal to arrange pixels in a matrix. I do.

In another reflection type liquid crystal display device of the present invention, one member formed by subjecting one main surface of a substrate to sandblast treatment and sequentially laminating a light reflection film, a transparent electrode, and an alignment layer on the one main surface. And the other member formed by sequentially laminating a transparent electrode and an alignment layer on a transparent substrate, and by interposing a nematic liquid crystal, pixels are arranged in a matrix.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a reflection type liquid crystal display device of the present invention will be described in detail with reference to FIGS. (Example 1) In the reflection type liquid crystal display device 1 of FIG. 1, 2 is a segment side glass substrate, 3 is a common side glass substrate, and for one of the members, one main surface of the glass substrate 2 is sandblasted. Chrome and aluminum, which are roughened by the treatment and are arranged in large numbers on this rough surface 2a in parallel.
An electrode 5 made of a metal such as silver and having light reflectivity was formed. A smooth film 6 made of SiO ₂ was formed on the electrode 5 by a sputtering method or a dipping method, and rubbed on the smooth film 6 in a certain direction. An alignment film 7 made of a polyimide resin is sequentially formed.

The other member is a glass substrate 3
A color filter 10 arranged for each pixel and a black matrix 11 made of chromium metal or a photosensitive resist arranged between the color filters 10 are formed thereon.

The color filter 10 is of a pigment dispersion type,
That is, a photosensitive resist prepared in advance with a pigment is applied on a substrate and formed by photolithography. R, G, and B in the figure indicate red, green,
The color filter 10 is colored blue.

An overcoat layer 12 made of an acrylic resin and a plurality of transparent electrodes 13 made of ITO arranged in parallel are formed thereon. This transparent electrode 13 is orthogonal to the electrode 5. Further, an alignment film 14 made of polyimide resin rubbed in a certain direction on the transparent electrode 13
Is formed.

Each of the glass substrates 2, 3 formed as described above
Are bonded by a sealant 16 via a liquid crystal layer 15 made of, for example, a chiral nematic liquid crystal twisted at an angle of 200 to 260 °. In addition, both glass substrates 2,
A large number of spacers 17 are arranged between the three to keep the thickness of the liquid crystal layer 15 constant.

Further, a retardation plate 18 made of polycarbonate or the like and an iodine-based polarizing plate 19 are provided outside the glass substrate 3.
And are sequentially stacked. In arranging these,
It is attached by applying an adhesive made of an acrylic material.

The above-mentioned smooth film 6, overcoat layer 1
2. The black matrix 11 may not be provided.

In the liquid crystal display device 1 having the above structure, incident light from external illumination such as sunlight or fluorescent light enters the glass substrate 3 and is reflected by the electrode 5 on the rough surface 2a through the color filter 10 and the liquid crystal layer 15. The reflected light is emitted through the liquid crystal layer 15.

Thus, according to the liquid crystal display device 1 of the present invention, the surface roughness of the rough surface 2a can be easily made uniform only by making the sand particle diameter uniform when the rough surface 2a is subjected to the sand blasting process. Similarly, the upper light-reflective electrode 5 could be uniformly roughened. As a result, the production cost can be reduced by increasing the manufacturing yield,
In addition, the contrast and brightness could be increased by such a uniform rough surface.

(Example 2) Next, another liquid crystal display device 20 of the present invention will be described with reference to FIG. The same parts as those of the liquid crystal display device 1 of FIG. In the liquid crystal display device 20, reference numeral 22 denotes a glass substrate on the segment side;
Is a common-side glass substrate, and one of the members is roughened by sandblasting one main surface of the glass substrate 21, and a light made of a metal such as chromium, aluminum, or silver is formed on the rough surface 21a. Reflective film 24 and SiO
_2, a color filter 10 arranged for each pixel on the smooth film 23, and each color filter 1
And a black matrix 11 arranged between zeros. Further, an overcoat layer 1 made of an acrylic resin
2 and a number of transparent electrodes 13 made of ITO arranged in parallel
And form. On the transparent electrode 13, an alignment film 14 made of a polyimide resin rubbed in a certain direction is formed.

As for the other member, a transparent electrode 27 made of ITO and arranged in parallel on the glass substrate 22 is provided.
An insulating layer 25 made of SiO ₂ and an alignment film 26 made of a polyimide resin rubbed in a certain direction are sequentially formed.

As in the case of Example 1, bonding is performed by a sealant 16 via a liquid crystal layer 15 composed of a chiral nematic liquid crystal including a large number of spacers 17. Further, a retardation plate 18 made of polycarbonate or the like and an iodine-based polarizing plate 19 are sequentially stacked outside the glass substrate 22. Note that the smooth film 23, the overcoat layer 12, the insulating layer 25, and the black matrix 11 may not be provided.

In the liquid crystal display device 20 having the above configuration,
Incident light from external lighting such as sunlight or fluorescent light is polarized
9, the phase difference plate 18, and the glass substrate 22, and further scattered by the light reflection film 24 through the liquid crystal layer 15 and the color filter 10, and the reflected light passes through the liquid crystal layer 15, the phase difference plate 18, and the polarization plate 19. Light is emitted. Even in such a configuration, the surface roughness of the rough surface 21a can be easily made uniform only by adjusting the sand particle size when the sand blasting rough surface 21a is sand blasted. Similarly, the surface roughness of No. 24 could be uniformly increased. As a result, the production cost could be reduced by increasing the production yield, and the contrast and brightness could be increased by such a uniform rough surface.

As described above, in the present invention, the sand blasting treatment of polishing the glass substrate surface with particles having the same sand particle diameter is performed, but the roughness of the rough surface 2a and the rough surface 21a is determined by the surface roughness. The roughness Ra may be set to 0.5 to 2.5 μm, and within this range, the brightness and the contrast can be increased most.

Example The luminance and contrast of the liquid crystal display device 1 of Example 1 and the liquid crystal display device 20 of Example 2 were measured, and the results shown in Table 1 were obtained. Surface roughness R of rough surface 2a of liquid crystal display device 1
a, the surface roughness Ra of the rough surface 21a of the liquid crystal display device 20 is 1.0 μm.

As a comparative example (Example 3), a liquid crystal display device was prepared. This liquid crystal display device 28 will be described with reference to FIG. The same parts as those of the liquid crystal display device 1 of FIG.

In this liquid crystal display device 28, the glass substrate 2 provided in the liquid crystal display device 1 is not provided with the roughened surface 2a by sandblasting, but is instead provided between the glass substrate 3 and the phase difference plate 18. Through a film 29 having a scattering function.

[0027]

[Table 1]

Luminance, contrast and chromaticity were measured using CS-100 manufactured by Minolta, and the same light source was irradiated to the liquid crystal panel at a fixed angle to measure the respective luminance, contrast and chromaticity. . The brightness and the contrast were represented by relative values, with 1.00 in each of the comparative examples.

As is clear from the results shown in Table 1, it is understood that the liquid crystal display devices 1 and 20 of the present invention have improved both luminance and contrast. In particular, the liquid crystal display device 1 of (Example 1) is superior to the liquid crystal display device 20 of (Example 2) by using the electrode as a reflecting surface.

When the reflection characteristics of each of the liquid crystal display devices were evaluated, the results shown in FIG. 4 were obtained.
For this measurement, the light source was irradiated with light from a direction of -30 °, and the light receiving angle was varied in the range of 0 to 60 ° to obtain the reflectance. As is clear from these results, it is understood that the liquid crystal display device of the present invention has improved angle dependence.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the spirit of the present invention. For example, in the above embodiment, the description has been made with the STN type simple matrix type color liquid crystal display device. However, a monochrome STN type simple matrix type liquid crystal display device or a TN type simple matrix type liquid crystal display device may be used. A similar effect can be obtained even with a liquid crystal display device of a liquid crystal display type or a twisted nematic liquid crystal display device such as a TN type active matrix type. Further, in the above embodiment, the sand blasting process is performed on the glass substrate. However, the sand blasting process may be performed on the plastic substrate instead. Furthermore, the surface roughening in the liquid crystal display device 1 of (Example 1) is changed to the inner surface side, and the outer surface of the glass substrate 2 is sandblasted in the liquid crystal display device 20 of (Example 2). Processing may be performed.

[0032]

As described above, according to the reflection type liquid crystal display device of the present invention, a uniform uneven surface can be easily produced only by sandblasting the substrate instead of using the scattering film. The light reflecting plate has a uniform uneven surface over the entire surface, and the uneven surface does not vary between the reflecting plates of each product. As a result, a low-cost reflective type that reduces production costs and increases contrast and brightness A liquid crystal display device could be provided.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a liquid crystal display device of the present invention.

FIG. 2 is an enlarged sectional view of a main part of another liquid crystal display device of the present invention.

FIG. 3 is an enlarged sectional view of a main part of a conventional liquid crystal display device.

FIG. 4 is a diagram showing a relationship between a light receiving angle and a reflectance.

[Explanation of symbols]

 1, 20 Reflective liquid crystal display device 2, 3, 21, 22 Glass substrate 2a, 21a Rough surface 5 Electrode 6, 23 Smooth film 7, 14, 26 Alignment film 10 Color filter 11 Black matrix 12 Overcoat layer 13 Transparent electrode 15 Liquid crystal layer 16 Sealant 17 Spacer 18 Retardation plate 19 Polarizing plate 24 Light reflection film 25 Insulation layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H090 HB08Y JA02 JA03 JA05 JB02 LA01 LA20 MB01 2H091 FA02Y FA08X FA08Z FA11X FA11Z FA14Y FA35Y FB02 FB08 FC25 FD06 FD15 GA01 GA02 GA03 GA06 GA07 GA16 GA17 LA12 LA18 2H09B GA12

Claims (2)

[Claims] A first main surface of the substrate is sandblasted,
Between one member formed by sequentially laminating an electrode film having light reflectivity and an alignment layer on the one main surface, and the other member formed by sequentially laminating a transparent electrode and an alignment layer on a transparent substrate A reflective liquid crystal display device in which pixels are arranged in a matrix with a nematic liquid crystal interposed therebetween. 2. A substrate is subjected to sandblasting on one main surface thereof.
Between one member formed by sequentially laminating a light reflection film, a transparent electrode, and an alignment layer on the one main surface, and the other member formed by sequentially laminating a transparent electrode and an alignment layer on a transparent substrate. A reflective liquid crystal display device in which pixels are arranged in a matrix with a nematic liquid crystal interposed therebetween.