JPH03214120A - Liquid crystal display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an active matrix liquid crystal display device, and more particularly to a method for correcting the viewing direction dependence of the amount of light transmitted through a liquid crystal.

[Prior Art] FIG. 4 is a circuit configuration diagram of an active matrix type liquid crystal display device, and FIG. 5 is a circuit configuration diagram showing a method of driving one transistor portion in FIG. 4.

The substrate on the side where the transistors of the matrix type liquid crystal display device are formed includes a plurality of scanning electrode wirings (1) and a plurality of signal electrode wirings (2) crossing these scanning wirings,
At the intersection, for example, T F T (thin film
An active element (4) such as a transistor (transistor) is formed, and a display m
It has a structure in which the poles (5) are connected. In a liquid crystal display device, scanning electrode wiring (1) from outside the liquid crystal display device
A signal is applied to TPT through the signal electrode wiring (2) to operate it, the signal output of TPT is applied to the display electrode (3), and the potential of this display electrode (3) is applied to the liquid crystal section (6). The liquid crystal section (6) modulates the light and displays.

FIG. 6 shows an example of the potential at the display electrodes connected to the TPTs connected to the scanning electrode wiring at the upper end of the display element, the center of the display element, and the lower end of the display element in a conventional active matrix liquid crystal display device. This is what is shown.

In a conventional active matrix liquid crystal display device, a voltage is applied evenly to the entire surface of the liquid crystal panel.

FIG. 7 is a diagram showing the dependence of the light transmittance of a liquid crystal section with the viewing direction facing upward on the angle at which the liquid crystal section is viewed. This is a phenomenon commonly observed in display elements, and what this figure means is that when looking up at the liquid crystal section from below, the light transmittance of the liquid crystal section is small, that is, the liquid crystal section appears dark; When viewed from above, the light transmittance of the liquid crystal section is high, that is, the liquid crystal section appears bright. In this example, if the viewing angle of the liquid crystal section is shifted 20' vertically, the apparent transmittance will be 40'.
% will change.

[Problems to be Solved by the Invention] Conventional active matrix liquid crystal display devices are configured as described above, so as display devices become larger,
This has the problem that the difference in brightness between the top and bottom ends of the display device appears to be large.

An explanatory diagram regarding this problem is shown in FIG. (7) is a large active matrix liquid crystal display device whose viewing direction is set upward; (8) is the position of the eye viewing the display device; (9) is the direction of the eye when looking up at the display device;
) is the line of sight direction when looking at the display device from the front, (11) is the line of sight direction when looking down at the display device, (12) is the position of the scanning electrode wiring at the top of the display device, and (13) is the direction at the center of the display device. The position of the scanning electrode wiring, (14) represents the position of the scanning electrode wiring at the bottom end of the display device, the arrow (]5) represents the intensity of the light that is modulated in the liquid crystal part of the display device and transmits upward, and the arrow (16) ) represents the intensity of light that is modulated in the liquid crystal part of the display device and transmitted in the horizontal direction, and arrow (17) represents the intensity of light that is modulated in the liquid crystal part of the display device and transmitted in the downward direction. The relationship between the strength of light is (
17)<(16)<(15), and this magnitude relationship is explained from FIG. therefore,
Looking at the upper end of the display device at the eye position shown in Figure 8.
When the user wears a beard, the display device appears dark, and when looking down at the lower end of the display device, the display device appears bright.In other words, within the same display device, the problem arises that the upper side of the display device is dark and the lower side is bright.

This invention was made to solve the above-mentioned problems, and the purpose is to obtain a display device that can be seen with uniform brightness within the display surface even if the liquid crystal display device becomes larger. shall be.

[Means for Solving the Problems] A liquid crystal display device according to the present invention has been made to solve the problems as described in “-”, and constitutes a liquid crystal display device in which the viewing direction is set in the h direction. The potential applied to the display@electrode is transferred from the display electrode connected to the TPT connected to the upper scanning electrode wiring of the liquid crystal display device to the display electrode connected to the TPT connected to the lower scanning electrode wiring. A lower voltage is applied toward the electrode.

[Function] In the liquid crystal display device according to the present invention, an effective voltage higher than a normal driving effective voltage is applied to the liquid crystal section on the upper side of the liquid crystal display device, and as a result, the upper side of the display device, which conventionally appeared dark in a large liquid crystal display device, becomes bright. In addition, an effective voltage lower than the normal driving effective voltage is applied to the liquid crystal section on the lower side of the liquid crystal display, and as a result, the lower side of the display, which conventionally appeared bright, appears dark. This cancels out the unevenness in brightness on the upper and lower sides of the display surface that has been observed in the display device, making it possible to display a display with uniform brightness over the entire display surface.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an active matrix liquid crystal display device driven according to the present invention.
It shows the potential at the display flL electrode connected to the TPT connected to the scanning electrode wiring at the center of the display element and at the lower end of the display element. When the scanning original number is changed from the upper side to the lower side in the display device, the voltage V applied to the signal electrode wiring is directly applied to the display electrode at the upper end of one screen. At the bottom edge of the screen, voltage V, to voltage ΔV
A voltage v2 with a reduced value is applied to the liquid crystal section.

Several reports have been made so far regarding the phenomenon in which the voltage of 8 V decreases at the bottom edge of the display screen in liquid crystal display devices, and their contents can be found, for example, in IEICE's 61st Spring Annual Meeting Lecture No. 1224. Ya, 5ocict
y for Information Display
As discussed in detail in International Symposium Lecture No. 9.2, this is related to the capacitance CdS between the transistor section and the soot line. In this example, this CdS ([
By setting 11 to 0.22 pF, ΔV is approximately 0.
．． The voltage becomes 9V, and this 8.times.1.alpha. is a value sufficient to correct the difference in brightness between the -4- side and the lower side of the display device described above. Here, as a method to set the value of Cd S to 0.02 pF, AiwJ is added to a part of the transistor structure.
A light-shielding film is introduced, and the new shape of the transistor structure according to this embodiment is shown in FIG.

Furthermore, the liquid crystal section of the liquid crystal display device according to this embodiment is as follows.

It must have electro-optical properties such that the transmittance is high when viewed from above, but in order to achieve this, the inside of the two substrates that make up the liquid crystal display device is shown in Figure 3. This can be achieved by rubbing the liquid crystal material in the same direction with a cloth and rotating the liquid crystal material sandwiched therebetween counterclockwise.

In addition, in the embodiment L, the scanning direction of the scanning electrode wiring was performed from the top of the display device to the bottom.
In some cases, the scanning direction is reversed, starting from the bottom upwards.
In this case, the rubbing direction in Fig. 3 (2:3), (
The intention of the present invention can be achieved by reversing the directions of 24).

In addition, in the above embodiment, a voltage drop of 5 @ is generated by setting CdS to an appropriate value, but the off-leakage current Ioff of the transistor is set to an appropriate value, for example, 1
, OX 10-11A, similar effects were obtained.

[Effects of the Invention] As described in (2) above, according to this invention, a high effective 1B pressure is applied to the upper or lower liquid crystal part of a large active matrix display, which conventionally appears dark, while the other part appears bright. A low effective voltage is applied to the liquid crystal section on the side, making it possible to obtain a liquid crystal display device with uniform brightness within the display image.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 shows the driving voltage of the liquid crystal section according to an embodiment of the present invention.
F, waveform diagram, f! Figure S2 is a sectional view of the I/transistor portion of an active matrix liquid crystal display device 6 according to an embodiment of the present invention, and Figure 3 is a diagram showing the substrate of the active matrix liquid crystal display device according to an embodiment of the present invention being rubbed with a cloth. An explanatory diagram showing the direction, the direction in which the device is viewed, and how the display performance of the device is viewed. Figure 4 is a circuit diagram of the principle of an active matrix liquid crystal display device. Figure 5 is a driving method for one of the transistors in Figure 4. 6 is a driving voltage waveform diagram of the liquid crystal section of a conventional active matrix liquid crystal display device, and FIG. 7 is a diagram showing the light transmittance of the liquid crystal section with the viewing direction set upward. FIG. 8 is an explanatory diagram showing the viewing direction dependence. FIG. 8 is an explanatory diagram showing the intensity and direction of light emitted from the liquid crystal display device and the direction in which the device 6 is viewed. In the figure, (]) indicates the scanning electrode wiring (2) for the signal N, the polar line (3) for the glass substrate on which the wiring is formed, (4) for the 'I' F T, (5) for the display electrode, ( 18) and (1
9) is S ] N y insulating film, (20) is amorphous Si, (21) is A] light shielding film, (22)
is a substrate that is bonded together and has a liquid crystal in between, (23)
is the direction of rubbing the board on the upper side of the circle in (22) with a cloth, (24)
is the direction in which the lower white substrate in (22) is rubbed with a cloth. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] An insulating substrate and a counter electrode substrate each having a plurality of parallel scanning electrode wirings, a plurality of parallel signal electrode wirings intersecting the scanning wirings, and a transistor connected to the scanning electrode wirings and the signal electrode wirings. In an active matrix display device with a liquid crystal material interposed therebetween, the effective voltage applied to the liquid crystal is changed depending on the position of the row of the scan electrodes, and the scanning direction of the scan electrodes and the viewing direction of the liquid crystal material are changed. A liquid crystal display device characterized by being oriented in the opposite direction.