JP3155883B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a liquid crystal display device for displaying an arbitrary image, a plurality of stripe-shaped scanning electrode groups are arranged on one opposing substrate, and a plurality of stripes are arranged on the other substrate. Signal electrode groups are arranged so as to be orthogonal to the scanning electrode groups, and image display units (pixels) corresponding to the intersections of the scanning electrodes and the signal electrodes are arranged in a matrix in which the vertical and horizontal directions are orthogonal. (FIG. 1).

However, in order to increase the operation speed of the screen during voltage application driving, the intersection of one scanning electrode and one signal electrode is not set as a pixel which is an image display unit. A multiplex matrix having a configuration in which a plurality of signal electrodes are arranged so as to intersect one scanning electrode, that is, a configuration in which a plurality of pixels are arranged on one scanning electrode in a direction perpendicular to a longitudinal direction thereof (FIG. 1) ) Is valid. In this case, in order to shield the area between the pixels, the light shielding means (Black) is used.
Matrix; FIG. 4) is required.

When manufacturing a liquid crystal cell, it is necessary to perform relative positioning between a scanning electrode substrate and a signal electrode substrate, particularly in a step of bonding an opposing substrate on which electrodes are formed. However, if a displacement (alignment displacement) occurs in this position, a relative displacement occurs between the light shielding matrix and the wiring metal, and the aperture ratio of the pixels varies.
When the aperture ratio changes, the brightness and color balance of the display screen vary, which has been a problem.

As a technique aimed at solving the above problem, a method of correcting a change in aperture ratio due to misalignment by surrounding ITO, which is an electrode material, with a metal wiring smaller than the opening of the black matrix. However, according to this method (FIG. 8), since the pixels are surrounded by a metal having an opening area smaller than that of the black matrix, there is a disadvantage that the aperture ratio itself is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention has been found to solve the above-mentioned problems, and has the following arrangement. That is, a liquid crystal device in which liquid crystal is sandwiched between one substrate having a scanning electrode group and the other substrate having a signal electrode group disposed so as to vertically intersect the scanning electrode group. (I) the intersection of the scanning electrode group and the signal electrode group is divided into a plurality of regions having openings having a rectangular or substantially rectangular shape in the longitudinal direction of the signal electrode; The region is an image display unit, and (III) a metal wiring is formed at an end of the signal electrode. (IV) The metal in a region corresponding to the image display unit on the signal electrode. A metal pattern is formed on one of the two sides parallel to the wiring, and no metal pattern is formed on the two sides perpendicular to the metal wiring.
(V) the position of the side on which the metal pattern is formed is different for each adjacent pixel on one signal electrode; (VI)
The image display unit, the metal wiring, the metal pattern, is divided from each other by the and blanking black matrix, it is characterized in that.

[0007]

The present invention will be described below in more detail with reference to examples.

FIG. 12 is a schematic view showing a cross section of a liquid crystal device according to an embodiment of the present invention.

As shown in FIG. 1, the liquid crystal element includes a chiral smectic liquid crystal 1208, two glass substrates which hold the liquid crystal 1208 therebetween and face each other, and the liquid crystal is uniformly formed at an interface with the liquid crystal. An orientation control film having a uniaxial orientation axis for orientation is provided. Scan electrodes 1204a are formed on one substrate, and signal electrodes 1204b are formed on the other substrate. The liquid crystal is driven by applying a voltage between the electrodes.
One of the glass substrates (1201a in the figure) has M
A black matrix 1202 made of oTa or the like is formed, and further thereon, SiO ₂ , TiO ₂ , Ta ₂
An insulating film 1203 made of O ₅ or the like is provided.
Then, on the insulating film, a transparent electrode 1204a such as In ₂ O ₃ or ITO, and a metal wiring 1205a for Al or the like for increasing electric conductivity of the electrode are further provided.
On top of that, a 200-3000 mm thick Si
Insulating film 1206 made of O ₂ , TiO ₂ , Ta ₂ O ₅
a, Uniaxial orientation control film 1207a formed of polyimide
Are formed. On the other substrate (121b in the figure), a black matrix 1202 and its insulating film 12
03, a transparent electrode 1204b, a metal wiring 1205b, an insulating film 1206b, and an orientation control film 1 in this order from the substrate surface.
207b is provided.

[0010]

The orientation control films 1207a and 1207b have orientation directions of 1207a with respect to the orientation axis of 1207b.
When viewed from the substrate side on the 1207a side, the orientation axis of
The rubbing process (direction of arrow A) is performed so that the film is uniaxially oriented so as to have an intersection angle of ° and is oriented in the same direction (direction A in FIG. 12). Hereafter, as described above, the angle between the orientation axes is defined such that the counterclockwise case has a positive value when viewed from the substrate side of the orientation of 1207a with reference to the orientation axis of 1207b, as described above. .

The distance between the substrates 1201a and 1201b is
The distance is sufficiently small to suppress the development of the helical structure of the chiral smectic liquid crystal 1208, and is 0.1 to 3 μm.
Is set to Here, the thickness is set to 1.2 to 1.3 μm.
This distance is maintained by bead spacers 1209 (silica beads, alumina beads, etc.) arranged between the two substrates.

The liquid crystal 1208 is a chiral smectic liquid crystal having bistability, and 120a and 120b are polarizing plates.

Here, a metal pattern (shaded portion) having a shape as shown in FIG. 2 was formed on the signal electrode. The dimensions of each part are as described in the figure.

As a result, the space between the pixels is shielded from light by both the metal pattern of FIG. 2 and the black matrix (FIG. 4), and the opening of the pixel finally corresponds to the portion surrounded by the dotted frame in FIG. The size of the pixel is 200 × 200μ
m, minimum line width of metal wiring is 10 μm, minimum line interval is 10 μm
m and the assembling accuracy of the substrate are ± 10 μm in both the vertical and horizontal directions. The total number of pixels on the display surface is 640 × 480.

The liquid crystal element has a pixel pitch of 200 μm × 2
00 μm, 640 × 480 pixels with the minimum metal line width 1
The multi-matrix electrodes were configured so that the substrate assembly accuracy was ± 10 μm for each of the upper, lower, left and right sides, and the aperture ratio was constant (FIG. 6). The aperture ratio T obtained at this time is such that the solid line opening has a rectangular shape of 130 × 170,

[0017]

[Outside 1]

When the device was driven and the pixels were visually observed with a microscope, no alignment defect was observed.

(Comparative Example) The device configuration is the same as that of the first embodiment except that the signal electrode, the metal wiring of the signal electrode, and the black matrix are formed as shown in FIG. In this case, a metal wiring pattern such as 71 is formed on the signal electrode. The dimensions of each part are as described in the figure.
The shape of the black matrix is as shown in FIG.
The opening of the pixel surrounded by the metal wiring and the light shielding matrix has a rectangular shape of 130 × 150 as shown in FIG.

The aperture ratio T 'obtained at this time is

[0021]

[Outside 2]

The device was driven by applying a voltage, and the pixel group was visually observed with a microscope. As a result, an alignment defect was observed in a region 101 as shown in FIG. Here, in the case of this comparative example, the metal wiring is also provided on the end face of the scanning electrode. In this case, the metal wiring on the scanning electrode side and the metal wiring on the signal electrode side are formed as shown at 91 in FIG. There is an area where the wiring intersects and crosses. It has been observed that the above-mentioned defects are generated from the intersections, and the liquid crystal layer thickness is locally reduced at the intersections, so that the electric field strength at the intersections is increased. It is thought that it was done.

[0023]

As described above, the liquid crystal display device having the structure according to the present invention suppresses a change in the aperture ratio of each pixel in the display surface area, and at the same time, allows each pixel to have a larger aperture than before. It is possible to give a rate.

At the same time, it was possible to prevent an alignment defect caused by a difference in the thickness of the liquid crystal layer at the intersection of the wiring metals.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electrode and a pixel configuration in a multi-matrix liquid crystal display device of the present invention.

FIG. 2 is a diagram showing metal wiring on a signal electrode side substrate of the liquid crystal display device of the present invention.

FIG. 3 is a diagram showing metal wiring on a scan electrode side substrate of the present invention.

FIG. 4 is a diagram showing a form of a black matrix used in a matrix type liquid crystal display device.

FIG. 5 is a diagram illustrating an example of a pixel arrangement in the liquid crystal display device of the present invention.

FIG. 6 is a diagram showing a matrix electrode arrangement.

FIG. 7 is a diagram showing a metal wiring pattern on a signal electrode in the related art.

FIG. 8 is a diagram showing a conventional method for preventing misalignment of a counter substrate of a liquid crystal display device.

FIG. 9A is a view showing a region where a metal pattern on a scanning electrode side substrate and a metal pattern on a signal electrode substrate are arranged to face each other in the embodiment of the present invention. (B) is a diagram showing a region where a metal pattern on a scanning electrode side substrate and a metal pattern on a signal electrode substrate are opposed to each other in a comparative example.

FIG. 10 is a view showing a region where an alignment defect has occurred in the comparative example shown in FIG. 9 (b).

FIG. 11 shows an alignment film material used in Examples.

FIG. 12 is a sectional view of a liquid crystal display device according to an example of the present invention.

[Explanation of symbols]

Reference Signs List 11 metal wiring provided on end face of signal electrode 12 metal wiring provided on end face of scanning electrode 13 opening area corresponding to one pixel 21 metal electrode provided on signal electrode 31 metal provided on scanning electrode Electrode 41 Light-shielding matrix 51 Opening area of one pixel 61 Scanning electrode 62 Signal electrode 71 Metal electrode provided on conventional signal electrode 91 Area facing metal electrode 101 Alignment defect of liquid crystal element having conventional metal wiring configuration Expression region

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1343 G02F 1/1335

Claims (2)

(57) [Claims] 1. A liquid crystal in which a liquid crystal is sandwiched between one substrate having a scanning electrode group and the other substrate having a signal electrode group disposed so as to vertically intersect with the scanning electrode group. (I) an intersection of the scanning electrode group and the signal electrode group is divided into a plurality of regions having an opening having a rectangular or substantially rectangular shape in a longitudinal direction of the signal electrode; II) the area is an image display unit; (III) a metal wiring is formed at an end of the signal electrode; and (IV) an area corresponding to the image display unit on the signal electrode. 2 parallel to metal wiring
A metal pattern is formed on one of the sides, and no metal pattern is formed on two sides perpendicular to the metal wiring. (V) The position of the side on which the metal pattern is formed characterized but different for each adjacent pixel on one of the signal electrodes, the (VI) wherein the image display unit, the metal wiring, the metal pattern, is divided from each other by the and blanking black matrix, it Liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein said light shielding means is provided on a substrate having a scanning electrode.