JPH0720660Y2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a liquid crystal display device used in a liquid crystal television or the like.

(B) Conventional technology Conventionally, in an active matrix type liquid crystal display device, even if the same voltage is written to a pixel, the bottom row is compared with the top row depending on the timing when the gate is turned on and the timing when the polarity of the data signal is inverted. It is well known that the voltage drop becomes larger, the brightness gradient is generated in the vertical direction of the screen, and the brightness becomes darker as it goes downward (for example, JP-A-58).
-158691, 61-256389, 62-151081).

Further, in the driving method in which the voltage applied to the counter electrode is not DC but a voltage whose polarity is inverted (see, for example, Japanese Patent Application Laid-Open No. 58-21792), a TFT which is a switching element is also used.
(Thin film transistor), gate. The ratio of the parasitic capacitance (C _G ) between the sources and the capacitance of the pixel (C _L ) (C _G / C _L ) causes a vertical brightness gradient.

Various driving methods have been proposed as methods for reducing or eliminating this brightness gradient. For example, JP-A-61-256389
Japanese Unexamined Patent Publication No. 58-158691 discloses a method of applying a gate voltage enough to ensure that the TFT is off, and Japanese Unexamined Patent Publication No. 58-158691 discloses a method of modulating a drive signal.

However, even if these methods are used, it is difficult to completely eliminate the above-mentioned brightness gradient in consideration of variations in the characteristics of the switching element, and in order to do so, it is necessary to increase the number of circuits and drive high voltage. Required, increased power consumption, TFT
And the problem of withstand voltage of peripheral circuits will appear.

(C) Problems to be Solved by the Invention As described above, according to the present invention, there is no need to add a circuit for the luminance gradient in the vertical direction or change the driving circuit such as increasing the voltage.
It is intended to reduce it.

(D) Means for Solving the Problems The present invention is directed to an active matrix substrate formed by combining a plurality of pixel electrodes and a plurality of switching elements, and a common electrode formed on a surface facing the pixel electrodes. In a liquid crystal display device in which a liquid crystal is held by a substrate and a signal is supplied so as to sequentially excite the switching elements from the upper side to the lower side, an alignment layer is formed on the inner surfaces of the active matrix substrate and the counter substrate. The orientation layer is oriented so that the preferential viewing angle is in the upward direction,
In addition, the angle between the viewpoint and each part of the substrate is smaller from the upper part to the lower part of the substrate.

(E) Action In the present invention, the alignment layer is oriented so that the preferential viewing angle is in the upward direction, and the lower part of the panel is easier to see than the upper part of the panel. The brightness is uniform.

(F) Embodiment FIG. 1 is a side view showing an embodiment of the present invention. In this figure, (1) is a circuit housing portion, and (2) is a display portion having a panel (3) fixed to the front surface. The display section (2) has an equivalent circuit as shown in FIG. 2, which includes a plurality of pixel electrodes (4) ... And a plurality of switching elements (TFT) (5).
An active matrix substrate formed by combining ...
The liquid crystal is held by the counter substrate having the common electrode (6) formed on the surface facing the pixel electrodes (4), so that the switching elements (5) are sequentially excited from the upper side to the lower side. Signal is supplied.

A well-known alignment layer is formed on the inner surfaces of the active matrix substrate and the counter substrate, and the alignment layer is subjected to an alignment treatment so that the preferential viewing angle is in the upward direction.

Therefore, even if the brightness decreases from the upper part to the lower part of the panel (3), the alignment layer is subjected to the alignment treatment so that the preferential viewing angle is directed upward as described above. From the position where the angle with each part of the panel becomes smaller from the upper part to the lower part of the substrate, the entire panel (3) looks uniform brightness to the viewer.

(G) Effect of the Invention According to the present invention, in the active matrix type liquid crystal display device, the problem of the vertical brightness gradient caused by the structure or the form of the circuit configuration is to increase the power consumption by adding a special circuit. Instead, it can be easily reduced by devising the direction of the alignment treatment.

[Brief description of drawings]

Each of the drawings shows an embodiment of the present invention. FIG. 1 is a side view and FIG. 2 is an equivalent circuit diagram. (1) …… Circuit compartment, (2) …… Display, (3) ……
Panel, (4) pixel electrode, (5) ... TFT (switching element), (6) ... common electrode.

Claims (1)

[Scope of utility model registration request] 1. A liquid crystal is sandwiched between an active matrix substrate formed by combining a plurality of pixel electrodes and a plurality of switching elements, and a counter substrate having a common electrode formed on a surface facing the pixel electrodes. In a liquid crystal display device in which a signal is supplied so as to sequentially excite the switching elements from the upper side to the lower side, the alignment layers formed on the inner surfaces of the active matrix substrate and the counter substrate have a preferential viewing angle in the upward direction, and the viewpoint and the A liquid crystal display device, wherein an angle with each part of the substrate is reduced from an upper portion of the substrate to a lower portion thereof.