JP2000019498A - Reflective type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display with enhanced contrast and brightness. SOLUTION: In the reflective type liquid crystal display device 1, one member obtained by successively forming a flattening film 4, a transparent electrode 5, an insulating layer 6, and an alignment layer 7, on a sandblasted and roughened surface 2a of a glass substrate 2, and the other member comprising a glass substrate 3, on which a light reflecting layer 8, an insulating layer 9, a color filter 10, an insulating layer 12 and a transparent electrode 13 are formed, are stuck together 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, for reflective liquid crystal displays that do not use a backlight,
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 on a liquid crystal display device is treated so that the surface thereof becomes uneven (Japanese Patent Laid-Open No. Hei 4-
No. 75022).

(2) A liquid crystal display device is provided with a mirror-like reflector, and a scattering film is further provided on the front surface of the device (Japanese Patent Laid-Open No. Hei 8-201802).

[0007]

[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.
Further, in the technique (2), the contrast is reduced due to back scattering of the incident light.

Accordingly, the present invention has been completed in view of the above circumstances, 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 sand blasting process, thereby reducing the production cost.

[0010]

The reflection type liquid crystal display device of the present invention comprises one member formed by sequentially laminating a transparent electrode and an alignment layer on a sandblasted transparent substrate, and a light reflection surface on one main surface. The transparent electrode and the other member formed by sequentially laminating the alignment layer on the substrate having the above are bonded together via a nematic liquid crystal to arrange the pixels in a matrix.

Another reflection type liquid crystal display device of the present invention comprises one member formed by sequentially laminating a transparent electrode and an alignment layer on a transparent substrate subjected to sandblasting, and an electrode film having light reflectivity on the substrate. It is characterized in that pixels are arranged in a matrix by bonding the other member formed by sequentially laminating the alignment layer and the other member via a nematic liquid crystal.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an enlarged sectional view of a main part of a reflection type liquid crystal display device of the present invention in Example 1, and FIG. 2 is a main portion of another reflection type liquid crystal display device of the present invention in Example 2. It is a part enlarged sectional view. FIG. 3 is an enlarged sectional view of a main part of a conventional reflection type liquid crystal display device.

(Example 1) In the reflection type liquid crystal display device 1 shown in FIG. 1, 2 is a segment side glass substrate which is the transparent substrate, 3 is a common side glass substrate, and the one member is made of glass. One principal surface of the substrate 2 is roughened by sandblasting, and a smooth film 4 made of SiO _{2 is formed} on the rough surface 2a by a sputtering method or a dipping method. A transparent electrode 5 made of, an insulating layer 6 made of SiO _2, and an alignment film 7 made of a polyimide resin rubbed in a certain direction are sequentially formed.

As for the other member, the glass substrate 3
On the light reflection layer 8 made of aluminum metal and SiO ₂
And a color filter 10 disposed for each pixel, and a chromium metal or photosensitive resist black matrix 11 disposed between the color filters 10 on the insulating layer 9. I have. The light reflection layer 8 is formed by sputtering.

The color filter 10 is formed by a pigment dispersion method, that is, a method in which a photosensitive resist previously prepared with a pigment is applied on a substrate, and photolithography is performed. R, G, and B in the figure are red, respectively.
The color filter 10 is colored green and blue.

An insulating layer 1 made of an acrylic resin is formed thereon.
2 and a number of transparent electrodes 13 made of ITO arranged in parallel
And form. The transparent electrode 13 is the transparent electrode 5
And orthogonal. Further, an alignment film 14 made of a polyimide resin rubbed in a certain direction is formed on the transparent electrode 13.

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 2.
And are sequentially stacked. In arranging these,
It is attached by applying an adhesive made of an acrylic material.

The smoothing film 4 and the insulating layers 6, 9, 1
2. The black matrix 11 may not be provided.

In the liquid crystal display device 1 having the above-described structure, the irradiation light from the external illumination such as sunlight, fluorescent light, etc.
, The light sequentially passes through the phase difference plate 18 and the glass substrate 2, the incident light is forward scattered by the rough surface 2 a, is reflected by the light reflecting layer 8 through the liquid crystal layer 15, and the reflected light is passed through the liquid crystal layer 15. The light is scattered by 2a and emitted. In the present invention, the surface roughness of the rough surface 2a can be easily made uniform only by adjusting the sand particle size when the rough surface 2a is subjected to the sand blast treatment, whereby the back scattering is reduced,
As a result, the brightness and the contrast were improved.

(Example 2) Next, another liquid crystal display device 20 of the present invention will be described with reference to an enlarged sectional view of a main part of FIG. In addition,
The same parts as those of the liquid crystal display device 1 of FIG.

In this liquid crystal display device 20, reference numeral 22 denotes a segment-side glass substrate, reference numeral 21 denotes a common-side glass substrate.
The one main surface is roughened by sandblasting, a smooth film 23 made of SiO ₂ is formed on the rough surface 21a, and the color filter 1 arranged for each pixel on the smooth film 23 is formed.
0 and a black matrix 11 arranged between the color filters 10. Further, an insulating layer 12 made of an acrylic resin and a plurality of transparent electrodes 13 made of ITO arranged in parallel are formed. 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 light-reflective electrode 24 made of chromium metal or aluminum metal arranged in parallel on a glass substrate 22, an insulating layer 25 made of SiO ₂ , and a polyimide resin rubbed in a certain direction And an alignment film 26 composed of the same.

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 27 made of polycarbonate or the like and an iodine-based polarizing plate 28 are sequentially stacked outside the glass substrate 21. Similarly, the smooth film 23, the insulating layers 12, 25, the black matrix 1
1 need not be provided.

In the liquid crystal display device 20 having the above configuration,
Irradiation light from external lighting such as sunlight, fluorescent light, etc.
8, the phase difference plate 27, and the glass substrate 21 sequentially, and this incident light is forward-scattered by the rough surface 21a, and
The light is reflected by the electrode 24 through the
5, the light is scattered by the rough surface 21a and emitted.
Also in such a configuration, the backscattering was reduced by the sandblasted rough surface 21a, thereby improving the brightness and contrast.

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

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.

However, as a comparative example (Example 3), a liquid crystal display device was used. This liquid crystal display device 29 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 29, the glass substrate 2 provided in the liquid crystal display device 1 is not provided with the roughened surface 2a and the smooth film 4 by sandblasting. 18 and a film 30 having a scattering function.

[0030]

[Table 1]

Luminance, contrast and chromaticity were measured using CS-100 manufactured by Minolta, and the same light source was applied to the liquid crystal panel at a fixed angle to measure the respective luminance, contrast and chromaticity. .

The brightness and the contrast were expressed as 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 device of the present invention has improved both luminance and contrast. In particular, the liquid crystal display device of Example 2 is superior to the liquid crystal display device of Example 1 by using the electrode as a reflecting surface.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements can be made without departing from the scope of the present invention.

For example, in the above embodiment, S
Although the description is made with reference to a TN type simple matrix type color liquid crystal display device, a monochrome STN type simple matrix type liquid crystal display device, or a TN type simple matrix type liquid crystal display device or a TN type active liquid crystal display device may be used. A similar effect can be obtained even with a twisted nematic liquid crystal display device such as a matrix type.

Further, in the above embodiment, the sand blasting is performed on the glass substrate. Alternatively, the sand blasting may be performed on the plastic substrate.

Further, instead of roughening the surface of the liquid crystal display device 1 of Example 1 on the inner surface side, the liquid crystal display device 20 of Example 2 also
May be subjected to sandblasting.

[0038]

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 a transparent substrate instead of using a scattering film. As a result, backscattering was reduced, and as a result, a low-cost reflective liquid crystal display device with increased contrast and brightness could be provided.

In addition, in another reflection type liquid crystal display device of the present invention, one electrode is formed as a light reflection surface, so that the contrast and the brightness are further improved as compared with the combined structure of the transparent electrode and the light reflection layer. I was able to.

[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.

[Explanation of symbols]

 1,20 reflective liquid crystal display device 2,3,21,22 glass substrate 2a, 21a rough surface 4,23 smooth film 5,13 transparent electrode 6,12,25 insulating layer 7,14,26 alignment film 8 light reflective layer Reference Signs List 10 color filter 11 black matrix 15 liquid crystal layer 16 sealant 18, 27 retardation plate 19, 28 polarizing plate 24 light-reflective electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H090 HB08Y HB13X JB02 KA05 KA08 LA06 LA15 LA20 MB01 2H091 FA08X FA08Z FA11Z FA14Z FA35Z FB02 FC25 GA01 GA03 GA06 HA07 HA10 LA16 LA17 5C094 AA05 AA15 EA11 AE04

Claims (2)

[Claims] 1. A member in which a transparent electrode and an orientation layer are sequentially laminated on a transparent substrate subjected to sandblasting, and a transparent electrode and an orientation layer are sequentially laminated on a substrate having a light reflection surface on one main surface. A reflective liquid crystal display device in which pixels are arranged in a matrix by bonding the other member to the other member via a nematic liquid crystal. 2. A member formed by sequentially laminating a transparent electrode and an alignment layer on a transparent substrate subjected to sandblasting, and the other member formed by sequentially laminating an electrode film having light reflectivity and an alignment layer on a substrate. A reflective liquid crystal display device in which pixels are arranged in a matrix by bonding the above-mentioned members through a nematic liquid crystal.