JP2665066B2 - Active matrix driven 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 a liquid crystal display, and more particularly to an active matrix driven liquid crystal display using thin film transistors.

[0002]

2. Description of the Related Art Recent active matrix drive type liquid crystal displays have made remarkable progress and are being actively applied to laptop personal computers and the like due to features such as high image quality and high definition. An active matrix drive type liquid crystal display includes an active matrix substrate and a counter electrode substrate. A drive element array such as a thin film transistor (hereinafter, referred to as a “TFT”) is disposed on the active matrix substrate, and a display area is disposed on the counter electrode substrate. Opposing electrodes are formed on the entire surface.

FIG. 9 is a plan view of a conventional active matrix substrate, and FIG. 10 is a cross-sectional view of a part thereof (a line AA 'in FIG. 9). 9 and 10, 1 is a glass substrate, 3 is a data line, 4 is a gate bus, 5 is a TFT, 6 is a pixel electrode, 7 is a passivation film, and 10 is an alignment film. FIG. 11 is a plan view of a conventional counter electrode substrate, and FIG. 12 is a cross-sectional view of a part thereof (along the line AA 'in FIG. 11). In FIG. 11, a figure surrounded by a line is an opening of the black mask 8. In FIG. 12, reference numeral 2 denotes a glass substrate, on which a black mask 8 made of a metal thin film such as chromium (Cr) is formed on a part of its surface, and ITO (Indium Tin Oxid) is formed on the entire display region.
The counter electrode 9 and the alignment film 10 of e) are formed.

An active matrix drive type liquid crystal display is formed by bonding the two substrates and injecting a liquid crystal between the two substrates. FIG. 13 is a plan view of a conventional active matrix drive type liquid crystal display, and FIG. 14 is a part thereof (AA ′ in FIG. 13).
(Line) is a sectional view. As shown in FIGS. 13 and 14, the data lines 3 on the active matrix substrate, the wiring region of the gate bus 4, and the TFT 5 region are shielded from light by the black mask 8 on the counter electrode substrate.

There are two purposes for providing the black mask 8. One is to shield the TFT channel region from light and suppress the photoelectric effect due to incident light from the counter substrate side. And the other is the reference (1) A.LIEN "IDRC EU
RODISPLAY'90 DIGEST P248-251 ", (2) T. ONOZAWA
"JJAP 1990 Vol.29 No.10 P1853-1855", (3)
Eiichi Takahashi et al. “16th LCD Panel Meeting Material P212-21
13 "and (4) a region in which liquid crystal molecules operate due to an electric field between the data line 3, the gate bus 4, and the counter electrode 9 as described in Japanese Utility Model Laid-Open No. 2-38263 (FIG. 13). 14 and shaded portions in FIG. 14). For example, in the case of the TN method, since the light transmittance of this area cannot be controlled, unless this area is shielded by the black mask 8, the display quality such as contrast is reduced.

Here, the point that the liquid crystal molecules operate due to the electric field between the data line 3, the gate bus 4, and the counter electrode 9 will be described. FIG. 15 is a distribution diagram of lines of electric force between data lines, pixel electrodes, and counter electrodes in a conventional active matrix drive type liquid crystal display.
FIG. 2 is a distribution diagram of lines of electric force between a gate bus, a pixel electrode, and a counter electrode in a conventional active matrix drive type liquid crystal display.

As shown in FIG. 15, lines of electric force are distributed from the data line 3 to the counter electrode 9 and the pixel electrode 6.
In particular, since the distance between the data line 3 and the counter electrode 9 is short, the electric field therebetween is strong, and the horizontal component of the electric field affects the liquid crystal molecules. Leakage has occurred and disclination lines due to reverse tilt have occurred on the pixel electrodes 6. This is the same for the gate bus 4 shown in FIG.

In the above-mentioned references (1) and (2), the electric field distribution is obtained by simulation, and the position where disclination occurs is obtained. In the above-mentioned reference (3), the fact that the tilt angle is related to this phenomenon is determined by an experiment.

[0009]

However, these documents do not specify a specific countermeasure, and the countermeasure described in the above-mentioned reference (4) has a drawback that the clear viewing direction changes. is there. The black mask 8 has a large viewing angle (when the liquid crystal display is viewed from an oblique direction).
Also, in order to achieve the above-mentioned object, the pixel electrode 6 is provided so as to overlap with the pixel electrode 6 to some extent. According to the above-mentioned references (1) and (2), this overlap amount needs to be at least about 20 microns. However, as the definition of the liquid crystal display increases, the aperture ratio of the black mask 8 decreases. Therefore, there is a problem in that the smaller the overlap amount is, the more desirable it is.

Further, a reverse tilt disclination line generated by the electric field distribution between the data line 3, the gate bus 4, the pixel electrode 6 and the counter electrode 9 is shown in FIG.
As shown in (1), since the light is generated by entering into the pixel region at the corner of the pixel electrode, it reaches the black mask opening beyond the overlap amount, and the display quality is degraded. If these areas are shielded from light by a black mask, the effect of disclination is removed, but there is a problem that the display luminance further decreases due to a further decrease in the aperture ratio.

An object of the present invention is to provide an active matrix drive type liquid crystal display in which the aperture ratio of a black mask is increased without solving the above-mentioned conventional problems and without impairing the high display quality of the active matrix drive type liquid crystal display. With the goal.

[0012]

In order to solve the above-mentioned problems, the present invention provides an active matrix driving type liquid crystal including an active matrix substrate, a counter electrode substrate, and a liquid crystal disposed between the two substrates. In a display, a counter electrode provided on a counter electrode substrate is provided with a stripe electrode for concentrating an electric field from a data line provided on an active matrix substrate, and provided on the active matrix substrate in parallel with the stripe electrode. This is an aggregate of stripe-shaped display electrodes provided so as to face the pixel electrodes provided.

Further, in an active matrix driving type liquid crystal display comprising an active matrix substrate, a counter electrode substrate, and a liquid crystal disposed between the two substrates,
A counter electrode provided on the counter electrode substrate is connected to a stripe electrode for concentrating an electric field from a data line provided on the active matrix substrate and the stripe electrode, and provided on the active matrix substrate. This is an aggregate of display electrodes arranged so as to face each other in substantially the same shape as the pixel electrodes.

Further, in order to solve the above problems, in the present invention, in addition to the above components, a black mask formed of a photosensitive resin in which a black pigment is dispersed is provided on the counter electrode substrate.

[0015]

According to the present invention, since the active matrix drive type liquid crystal display is constructed as described above, the electric field intensity is reduced in the region beside the data line, and unnecessary movement of the liquid crystal molecules beside the data line is reduced. This can prevent light leakage and disclination lines from occurring in the pixel electrodes.

Further, according to the present invention, since the active matrix drive type liquid crystal display is constituted as described above, the electric field intensity is reduced in the region beside the data line and the gate bus, and the data line and the gate bus beside. Unnecessary movement of the liquid crystal molecules is reduced. Accordingly, it is possible to prevent the occurrence of light leakage and the occurrence of disclination lines in the pixel electrodes.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a plan view of an active matrix drive type liquid crystal display according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of a part thereof (a line AA ′ in FIG. 1).

The features of this embodiment reside in the shape of the counter electrode 9 and the material of the black mask 8 on the counter electrode substrate. That is, the opposing electrode 9 (the hatched portion) is a stripe electrode 9a parallel to the data line 3 and having the same width.
And the pixel electrode 6 parallel to the stripe electrode 9a.
An aggregate of stripe-shaped display electrodes 9b having substantially the same width as that of FIG. These stripe electrodes 9a and 9b are all electrically connected outside the display area. The counter electrode 9 was formed by a known photolithographic etching technique. The black mask 8 was formed using a photosensitive resin (manufactured by Fuji Hunt) in which a black pigment was dispersed.

Then, a TN mode NB (normally black) mode liquid crystal display was formed using this counter electrode substrate and the same active matrix array substrate as the conventional one. The cell interval is 5 μm, and the thickness of the data line 3 is 1
μm, the width of the data line 3 is 8 μm, the distance between the data line 3 and the pixel electrode 6 is 10 μm, the distance between the gate bus 4 and the pixel electrode 6 is 10 μm, and the overlap amount between the pixel electrode 6 and the black mask 8 is 5 μm. did.

(Second Embodiment) FIG. 3 is a plan view of an active matrix drive type liquid crystal display according to a second embodiment of the present invention, and FIG. 4 is a cross-sectional view of a part thereof (a line AA 'in FIG. 3). . This embodiment is different from the first embodiment only in the shape of the counter electrode 9 on the counter electrode substrate. Therefore, only the counter electrode 9 will be described here.

In this embodiment, a counter electrode 9 (hatched portion) is a stripe electrode 9a parallel to the data line 3 and having the same width, and a T electrode is formed on the stripe electrode 9a.
An aggregate of display electrodes 9b having the same shape as the pixel electrode 6 connected on the FT 5 was formed. These stripe electrodes 9a are all electrically connected outside the display area. Counter electrode 9
The method of formation, the material of the black mask 8 and the like are the same as in the first embodiment.

Then, a TN mode NB (normally black) mode liquid crystal display was formed using this counter electrode substrate and the same active matrix array substrate as the conventional one. The size such as the cell interval is the same as in the first embodiment. FIG. 5 is a distribution diagram of lines of electric force between data lines, pixel electrodes, and counter electrodes in the active matrix drive type liquid crystal display according to the first and second embodiments of the present invention.
FIG. 6 is a distribution diagram of lines of electric force between a gate bus, a pixel electrode, and a counter electrode in an active matrix drive type liquid crystal display according to a second embodiment of the present invention.

In each of the above embodiments, the black mask 8 is formed of resin (insulator), and the stripe electrodes 9 for concentrating the electric field from the data lines 3 on the data lines 3 are formed.
a on the pixel electrode 6 and the same width as the pixel electrode 6 (first
Example) or the display electrodes 9b of the same shape (second example) are provided, and as shown in FIG. 5, the electric field intensity is reduced in the region beside the data line 3 and the influence on the liquid crystal molecules is reduced. Decreased compared to the conventional case.

Further, in the second embodiment, since the counter electrode 9 is not arranged on the gate bus 4, the electric field strength is reduced also in the region beside the gate bus 4 as shown in FIG. As a result, no disclination line due to the reverse tilt was generated in the pixel area. This effect was larger as the number of TFTs connected to one data line was turned on.

FIG. 7 is an explanatory view of a method for measuring the display characteristics of an active matrix drive type liquid crystal display. FIG. 8 is a display showing the measurement results of the respective embodiments of the present invention and the conventional example without a black mask in the NB system. It is a characteristic diagram. FIG.
In the following, the display area is divided into ten sections in the horizontal direction, and one measurement point is provided for each section. Then, the data signal is applied so that the black display ratio changes stepwise in steps of 10%.

As shown in FIG. 8, in the conventional embodiment, it can be seen that the black luminance increases as the black display ratio of a certain data line 3 decreases. Since an increase in the black luminance level immediately lowers the contrast, in the conventional example, the black mask 8 is formed so as to overlap the pixel electrode 6 in consideration of the viewing angle and disclination. In contrast, in the present embodiment, the black display transmittance (light leakage) increases slowly even when the black display ratio decreases. Therefore, even when the amount of overlap of the black mask 8 with respect to the pixel electrode 6 was set to 0, good display quality and viewing angle characteristics were obtained.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention. For example, in each of the embodiments described above, the black mask 8 made of an insulator is provided on the counter electrode substrate. The electric field strength beside the line 3 or the gate bus 4 decreases, and the effect on the liquid crystal molecules decreases.

In each of the above embodiments, the width of the stripe electrode 9a is the same as the width of the data line 3, and the width of the display electrode 9b is the same as the width of the pixel electrode 6. It is needless to say that deformations such as setting the width slightly narrower in consideration of the alignment error with the counter electrode substrate are possible. Further, in the present embodiment, the case of monochrome display is described. However, the same effect is obtained when color display is performed by providing a color filter on the counter electrode substrate.

[0029]

As described above in detail, according to the present invention, an active matrix substrate, a counter electrode substrate,
In an active matrix drive type liquid crystal display including a liquid crystal disposed between the two substrates, an electric field from a data line disposed on the active matrix substrate is concentrated on an opposing electrode disposed on the opposing electrode substrate. Liquid crystal beside the data line by forming an aggregate of stripe electrodes for the display and stripe-shaped display electrodes disposed in parallel with the stripe electrodes and opposed to the pixel electrodes disposed on the active matrix substrate. Since unnecessary movement of molecules was suppressed, light leakage and disclination lines in the pixel electrode did not occur.

According to the present invention, in an active matrix drive type liquid crystal display including an active matrix substrate, a counter electrode substrate, and a liquid crystal disposed between the two substrates, the active matrix substrate is disposed on the counter electrode substrate. A counter electrode having a substantially identical shape to a stripe electrode for concentrating an electric field from a data line disposed on the active matrix substrate and a pixel electrode connected to the stripe electrode and disposed on the active matrix substrate. By forming an assembly with display electrodes arranged to face each other,
Unnecessary movement of the liquid crystal molecules beside the data lines and the gate bus was suppressed, so that the occurrence of light leakage and the generation of disclination lines in the pixel electrodes were eliminated.

Further, since the black mask is formed of an insulating material, the opening of the black mask is made larger than before, and
In addition, it is possible to obtain good viewing angle characteristics even when the amount of overlap with the pixel electrode is reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of an active matrix driving type liquid crystal display according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of an active matrix drive type liquid crystal display according to a first embodiment of the present invention.

FIG. 3 is a plan view of an active matrix drive type liquid crystal display according to a second embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of an active matrix driving type liquid crystal display according to a second embodiment of the present invention.

FIG. 5 is a distribution diagram of lines of electric force between data lines, pixel electrodes, and counter electrodes in an active matrix drive type liquid crystal display according to an embodiment of the present invention.

FIG. 6 is a distribution diagram of lines of electric force between a gate bus, a pixel electrode, and a counter electrode in an active matrix drive type liquid crystal display according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a method for measuring display characteristics of an active matrix drive type liquid crystal display.

FIG. 8 is a display characteristic diagram of an active matrix drive type liquid crystal display according to an embodiment of the present invention and a conventional example.

FIG. 9 is a plan view of a conventional active matrix substrate.

FIG. 10 is a partial cross-sectional view of a conventional active matrix substrate.

FIG. 11 is a plan view of a conventional counter electrode substrate.

FIG. 12 is a partial cross-sectional view of a conventional counter electrode substrate.

FIG. 13 is a plan view of a conventional active matrix drive type liquid crystal display.

FIG. 14 is a partial cross-sectional view of a conventional active matrix drive type liquid crystal display.

FIG. 15 is a distribution diagram of lines of electric force between data lines, pixel electrodes, and counter electrodes in a conventional active matrix drive type liquid crystal display.

FIG. 16 is a distribution diagram of lines of electric force between a gate bus, a pixel electrode, and a counter electrode in a conventional active matrix drive type liquid crystal display.

FIG. 17 is an explanatory diagram of a reverse tilt decretion line in a conventional active matrix drive type liquid crystal display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 3 Data line 4 Gate bus 5 Thin film transistor (TFT) 6 Pixel electrode 7 Passivation film 8 Black mask 9 Counter electrode 9a Stripe electrode 9b Display electrode 10 Alignment film

Continuation of the front page (72) Inventor Tsutomu Nomoto 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (56) References JP-A-60-262137 (JP, A) JP-A 64-64 25133 (JP, A) JP-A-2-136223 (JP, A) JP-A-3-4214 (JP, A)

Claims (3)

(57) [Claims] 1. A active matrix substrate, a counter electrode substrate, the active matrix driven liquid crystal display and a liquid crystal disposed between the both substrates, active matrix and opposing electrode disposed on the counter electrode on the substrate
A stripe electrode for concentrating an electric field from a data line disposed on the substrate , and a stripe electrode parallel to the stripe electrode.
An active matrix drive type liquid crystal display, wherein the liquid crystal display is an aggregate of stripe-shaped display electrodes provided to face pixel electrodes provided on the active matrix substrate . Wherein the active matrix substrate, a counter electrode substrate, the active matrix driven liquid crystal display and a liquid crystal disposed between the both substrates, active matrix and opposing electrode disposed on the counter electrode on the substrate
A stripe electrode for concentrating an electric field from a data line disposed on the substrate , and a stripe electrode connected to the stripe electrode.
For display that is arranged to face the pixel electrode arranged on the active matrix substrate with almost the same shape .
Active matrix driving type liquid crystal display, characterized in that the assembly of the electrodes. 3. The active matrix drive type liquid crystal display according to claim 1, further comprising a black mask formed of a photosensitive resin in which a black pigment is dispersed on the counter electrode substrate.