JPH08179371A - Thin film transistor liquid crystal display device and its driving method - Google Patents

Abstract

PURPOSE: To reduce the source voltage amplitude in a thin film transistor liquid crystal display device. CONSTITUTION: In the thin film transistor liquid crystal display device provided with gate wiring 1, source wiring 2, storage capacitance wiring 3, a thin film transistor 6, a drain electrode 4, a counter electrode 7, plural sub-pixel electrodes 5a, 5b, a transfer capacitance 8 and liquid crystal capacitances 9a, 9b, the storage capacitance wiring consists of plural sub-storage capacitance wirings, and storage capacitances 10a, 10b exist between respective sub-pixel electrodes 5a, 5b and respective sub-storage capacitance wiring, and potential of a source electrode is transmitted to the drain electrode for the on period of the thin film transistor, and the potential of respective sub-storage capacitance wiring and the counter electrode are changed for the off period, and the potential of respective sub-pixel electrodes 5a, 5b are modulated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor liquid crystal display device which realizes a wide viewing angle.

[0002]

2. Description of the Related Art In recent years, thin film transistor liquid crystal display devices have been widely used in workstations, personal computers, portable televisions and the like, and their use range tends to expand. A problem with the conventional thin film transistor liquid crystal display device is that the viewing angle is narrow. As means for increasing the viewing angle, Japanese Patent Laid-Open No.
2-000012, 02-310534, 03-1
22621, 04-348323, 04-3483
There is a pixel division structure as proposed in each of Japanese Patent No. 24 and 05-107556. This is a method in which the pixel electrode is divided into sub-pixel electrodes and each sub-pixel has a different transmittance (T) -source voltage amplitude (V) characteristic.

However, in the pixel division structure, in principle, only a part of the source signal voltage is applied to the liquid crystal, resulting in a large amplitude of the source voltage.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to reduce the source voltage amplitude in a thin film transistor liquid crystal display device having a pixel division structure.

[0005]

In order to solve the above-mentioned problems, the present invention provides a gate wiring, a source wiring, and a storage capacitance wiring formed in a matrix on a first substrate. Drain electrode, pixel electrode,
In addition, a thin film transistor that adjusts conduction between the source wiring and the drain electrode according to the potential of the gate wiring is formed, a counter electrode is formed over a second substrate which is provided so as to face the first substrate, and a plurality of pixel electrodes are provided. In a thin film transistor liquid crystal display device that is formed from sub-pixel electrodes, has a transition capacitance between the drain electrode and each sub-pixel electrode, and has a liquid crystal capacitance between each sub-pixel electrode and a counter electrode, a plurality of storage capacitance lines are provided. The storage capacitors are formed from the sub-storage capacitance lines, and the storage capacitance is formed between each sub-pixel electrode and each sub-storage capacitance line.

Further, there is no transition capacitance between the drain electrode and the at least one subpixel electrode, and the drain electrode and the at least one subpixel electrode are directly electrically connected, or the storage capacitance is provided between the at least one subpixel electrode and the substorage capacitance line. Is not present and is electrically disconnected, or the gate wiring in the previous stage is at least 1
It may be configured such that one sub-storage capacitor wiring is also used.

Then, the potential of the source electrode is transmitted to the drain electrode during the ON period of the thin film transistor, and the potentials of the sub-storage capacitance lines and the counter electrode are changed during the OFF period to modulate the potential of the sub-pixel electrodes.

Alternatively, the method may be such that the potential of at least one sub-storage capacitance wiring is constant, or the potential of the counter electrode is constant.

[0009]

According to the above means, each transition capacitance, liquid crystal capacitance,
By appropriately changing, for each sub-pixel, the T value of each sub-pixel, the three kinds of capacitance values of the storage capacitor and the two kinds of voltage values of the storage compensation potential and the counter potential applied to each sub-storage capacitance wiring are appropriately changed. The −V characteristic can be changed. At the same time, since the liquid crystal applied voltage is generated with the voltage amplitude of the storage compensation potential and the counter potential in addition to the source voltage amplitude, the source voltage amplitude can be reduced.

[0010]

EXAMPLE An equivalent circuit diagram (FIG. 1), a potential relationship diagram (FIG. 2) and a TV characteristic diagram (FIG. 3) of a thin film transistor liquid crystal display device in an example of the present invention are shown.

In FIG. 1, 1 is a gate wiring, 2 is a source wiring, and 3 is a storage capacitor wiring, which are formed in a matrix on the first substrate. In this embodiment, the gate wiring at the previous stage also serves as the storage capacitance wiring 3. Reference numeral 4 is a drain electrode, 5 is a pixel electrode, 6 is a thin film transistor which adjusts the conduction between the source wiring 2 and the drain electrode 4 by the potential of the gate wiring 1, and is formed at each intersection of the gate wiring 1 and the source wiring 2. Reference numeral 7 is a counter electrode formed on the second substrate, which is installed so as to face the first substrate. 5a, 5b
Are subpixel electrode a and subpixel electrode b, and 8 is
It is a transfer capacitance existing between the drain electrode 4 and the sub-pixel electrode b5b. 9a and 9b are sub-pixel electrodes a5, respectively.
a is the liquid crystal capacitance a and liquid crystal capacitance b existing between the sub-pixel electrode b5b and the counter electrode 7. Reference numerals 10a and 10b are a storage capacitor a and a storage capacitor b formed between the subpixel electrode a5a, the subpixel electrode b5b and the storage capacitor wiring 3, respectively. Reference numeral 11 is a gate-drain parasitic capacitance of the thin film transistor.

In FIG. 2, 101 is a gate wiring 1.
, 102 is a source potential applied to the source wiring 2, 103 is a storage compensation potential applied to the storage capacitance wiring 3 which is also used by the gate wiring in the previous stage, 10
Reference numeral 7 is a counter potential applied to the counter electrode. In this embodiment, the potential of the counter electrode is constant.

In FIG. 3, 201a is a liquid crystal capacitance a.
In the liquid crystal capacitance b, the T-V characteristics a and 201b in FIG.
Characteristic b is weighted and averaged by each pixel area, and
It is a V characteristic. The horizontal axis shows the source potential amplitude (one side), and the vertical axis shows the transmittance of the panel.

According to this embodiment, the transition capacitance, the liquid crystal capacitance,
The T-V characteristic of each sub-pixel can be changed by appropriately changing the three types of capacitance values of the storage capacitance and the two types of voltage values of the storage compensation potential and the counter potential for each sub-pixel. . At the same time, the liquid crystal applied voltage is generated by the storage compensation voltage and the counter voltage in addition to the source voltage amplitude, so that the source voltage amplitude can be reduced.
Actually, while keeping the viewing angle characteristics at the same level as the conventional example, the source voltage amplitude (one side) from all white to all black is 2.5.
It can be realized with V.

In this embodiment, the gate wiring in the preceding stage also serves as the storage capacitance wiring, but the storage capacitance wiring may be an independent wiring. In addition, the storage capacitance wiring is formed of a plurality of sub storage capacitance wirings, and a storage capacitance is formed between each sub pixel electrode and each sub storage capacitance wiring, and the preceding gate wiring also serves as at least one sub storage capacitance wiring. Alternatively, a configuration may be considered in which all the storage capacitor wirings are independent wirings. Further, a configuration may be considered in which there is no storage capacitance between at least one subpixel electrode and the substorage capacitance line among the plurality of subpixel electrodes, and the subpixel electrodes are electrically disconnected.

In the present embodiment, the potential of the counter electrode is constant, but a method of changing the potential of the counter electrode may be considered. In addition, when a plurality of sub storage capacitor wirings are formed,
A method is also conceivable in which the potential of at least one sub storage capacitor wiring is constant. In any of the above cases, with this embodiment,
The same effect can be expected.

[0017]

As described above, according to the present invention, three types of capacitance values of each transition capacitance, liquid crystal capacitance, and storage capacitance, and two types of voltage values of storage compensation potential and counter potential, By appropriately changing each sub-pixel, the TV characteristic of each sub-pixel can be changed. At the same time, since the liquid crystal applied voltage is generated with the voltage amplitude of the storage compensation potential and the counter potential in addition to the source voltage amplitude, the source voltage amplitude can be reduced.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of a thin film transistor liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a potential relationship diagram of potentials applied to a thin film transistor liquid crystal display device in an example of the present invention.

FIG. 3 is a characteristic diagram of transmittance (T) -source voltage amplitude (V) of a thin film transistor liquid crystal display device according to an embodiment of the present invention.

[Explanation of symbols]

 1 gate wiring 2 source wiring 3 storage capacity wiring 4 drain electrode 5 pixel electrode 5a pixel electrode a 5b pixel electrode b 6 thin film transistor 7 counter electrode 8 transition capacity 9 liquid crystal capacity 9a liquid crystal capacity a 9b liquid crystal capacity b 10 storage capacity 10a storage capacity a 10b Storage capacitance b 101 Gate potential 102 Source potential 103 Storage compensation potential 107 Counter potential 201a TV characteristic a in liquid crystal capacitance a 201b TV characteristic b in liquid crystal capacitance b 201c TV characteristic of the whole pixel

Claims (7)

[Claims] 1. A gate wiring, a source wiring, and a wiring on a first substrate.
Storage capacitor wirings are formed in a matrix, and a drain electrode, a pixel electrode, and a thin film transistor that adjusts conduction between the source wiring and the drain electrode by a potential of the gate wiring at each intersection of the gate wiring and the source wiring. A counter electrode is formed on a second substrate that is disposed opposite to the first substrate, the pixel electrode is formed of a plurality of sub-pixel electrodes, and the drain electrode and each of the sub-pixel electrodes are formed. In a thin film transistor liquid crystal display device in which a transition capacitance exists for each sub-pixel electrode and a liquid crystal capacitance exists between the sub-pixel electrode and the counter electrode, a storage capacitance line is formed of a plurality of sub-storage capacitance lines, and each sub-pixel electrode And a storage capacitor is formed between each of the sub storage capacitor wirings. 2. The thin film transistor liquid crystal display device according to claim 1, wherein there is no transition capacitance between the drain electrode and the at least one subpixel electrode, and the drain electrode and the at least one subpixel electrode are electrically connected directly. 3. The thin film transistor liquid crystal display device according to claim 1, wherein there is no storage capacitance between at least one subpixel electrode and the substorage capacitance line, and the storage capacitance is electrically disconnected. 4. The thin film transistor liquid crystal display device according to claim 1, wherein the gate wiring in the preceding stage also serves as at least one sub storage capacitance wiring. 5. The potential of the source electrode is transmitted to the drain electrode during the ON period of the thin film transistor, and the potentials of the sub-storage capacitance lines and the counter electrode are changed during the OFF period to modulate the potential of each sub-pixel electrode. The method for driving a thin film transistor liquid crystal display device according to claim 1, wherein: 6. The method of driving a thin film transistor liquid crystal display device according to claim 5, wherein the potential of at least one sub-storage capacitance line is constant. 7. The method of driving a thin film transistor liquid crystal display device according to claim 5, wherein the potential of the counter electrode is constant.