JPH0887248A - Liquid crystal panel, its control method and liquid crystal display device - Google Patents

Abstract

PURPOSE: To assist driving force of a driver by supplying a precharge voltage different from a write voltage applied to a pixel electrode to a line and to rapidly stabilize the write voltage on the data line is regard to a liquid crystal display panel and a liquid crystal display device. CONSTITUTION: In an active matrix liquid crystal display panel provided with plural data lines LDD connected to a thin film transistor 12 applying the write voltage Vc to the pixel electrode 13, a line boost support means 11 supplying the precharge voltage VP to the data line LDD according to a data write signal WE is provided. The liquid crystal display device is provided with the liquid crystal display panel displaying gradation based on the voltage written bn the pixel electrode and a display driver controlling output of the display panel, and the display panel is constituted of the liquid crystal display panel.

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 panel, a method of controlling the same, and a liquid crystal display device. More specifically, it is of an active matrix type which applies a writing voltage to a pixel electrode to perform gradation display. It relates to improvements in liquid crystal displays. In recent years, semiconductor integrated circuits (hereinafter referred to as I
With the development of high integration and high density technology (referred to as C), TF
2. Description of the Related Art A liquid crystal display device (LCD: Liquid Crystal Display) in which T (Thin Film Transistor) is integrated is manufactured. The LCD is thinner and lighter in weight and lower in power consumption than a CRT (cathode ray tube), and has been advanced in colorization and high definition, and has been attracting attention as a display device for not only general household TVs but also portable devices.

According to this, as a driving IC for LCD, there are a digital method and an analog method in which a writing voltage is applied to a data line thereof. However, in order to perform full color display, an analog capable of displaying continuous gradation is used. The driver is excellent. However, in a liquid crystal display panel equipped with an analog driver, when the number of pixels is increased due to the demand for improvement in image quality and display quality, the driving capability of the built-in amplifier is unavoidably increased, and the pixel electrodes and wiring patterns are miniaturized. The load capacity increases. As a result, if the amplifier drive capability is increased, the power consumption internally increases, and the resistance value and parasitic capacitance also increase, increasing the time constant and stabilizing the write voltage of the data line early. Will be difficult.

Therefore, a precharge voltage different from the write voltage applied to the pixel electrode is supplied to the data line to assist the driving force of the driver, and the write voltage of the data line can be stabilized early. What is desired is a display panel, method, and device that can.

[0004]

2. Description of the Related Art FIG. 6 is an explanatory diagram relating to a conventional example. FIG. 6A is a configuration diagram of a liquid crystal display device according to a conventional example, and FIG. 6B is a waveform diagram of the data line thereof. For example, as shown in FIG. 6A, an active matrix liquid crystal display device that applies a writing voltage to a pixel electrode to perform multi-gradation display has a liquid crystal display panel 1,
The analog driver 4 and the gate driver 5 are provided.

The liquid crystal display panel 1 has a plurality of TFTs 2 connected to the data line LDD and the gate line LGG. The TFT 2 is connected to the pixel electrode 3. The data lines LDD are drawn out above and below the liquid crystal display panel 1 every other line, and are connected to the analog driver (driving IC) 4. The analog driver 4 has a data line LDD
A plurality of operational amplifiers that output the write voltage Vc are provided for each. The gate line LGG is drawn to either the left or right side of the display panel 1, and it is connected to the gate driver (driving IC) 5.

The function of the display panel is to operate from the gate driver 5 through the gate line LGG of the liquid crystal display panel 1 to T
A pixel selection signal is output to FT2, and in this state, the write voltage Vc is supplied from the operational amplifier of the analog driver 4 via the data line LGG, and the TFT2 is turned on, so that the write voltage Vc is written to the pixel electrode 3. Get caught. As a result, multi-gradation display based on the write voltage Vc is executed.

[0007]

By the way, according to the liquid crystal display panel 1 of the conventional example, a plurality of TFTs 2 connected to the data line L DD and the pixel electrode 3 for charging the writing voltage Vc are provided. The voltage Vc is supplied to the TFT 2 from the operational amplifier of the analog driver 4 provided for each data line LDD. Therefore, the following problems occur.

(1) When the number of pixels is increased due to the demand for improving the image quality and display quality of the liquid crystal display device, the analog driver 4
The driving capability of the operational amplifier is forced to increase. This is because as the number of pixels increases, the resistance value increases due to the miniaturization of the pixel electrode 3 and the wiring pattern, and the parasitic capacitance increases, so that the load capacitance of one data line LDD increases.

As a result, if the driving capability of the operational amplifier of the analog driver 4 is increased, the power consumed inside the amplifier increases. Therefore, it is an obstacle to lowering the consumption of the liquid crystal display device. Especially in battery-powered portable devices, the duration of use is shortened. (2) Since the resistance value and the parasitic capacitance increase, the time constant becomes large, the pull-up time of the data line LDD becomes long, and the write voltage Vc of the data line LDD cannot be stabilized early.

In general, the rising characteristic of the operational amplifier is more gradual than the falling characteristic. Therefore, when the drive waveform of the data line LDD has a large time constant, as shown in FIG. 2, the waveform rising state is higher than the waveform falling state. Becomes slower. As a result, the charging time of the write voltage Vc to the pixel electrode 3 is limited by the rising characteristics of the operational amplifier of the analog driver 4.

The present invention was created in view of the problems of the conventional example, and supplies a precharge voltage different from the write voltage applied to the pixel electrode to the data line to assist the driving force of the driver. It is also an object of the present invention to provide a liquid crystal display panel, a method of controlling the liquid crystal display panel, and a liquid crystal display device capable of stabilizing the write voltage of the data line at an early stage.

[0012]

FIG. 1 is a principle diagram of a liquid crystal display panel and a control method thereof according to the present invention.
5 shows the respective examples. As shown in FIG. 1, the first liquid crystal display panel of the present invention is an active matrix liquid crystal display panel having a plurality of data lines LDD to which a thin film transistor 12 for applying a writing voltage Vc to a pixel electrode 13 is connected. Write signal W
A precharge voltage V is applied to the data line L DD according to E.
A line boosting auxiliary means 11 for supplying P is provided.

In the first liquid crystal display panel of the present invention,
The line boosting assisting means 11 is connected between an auxiliary power supply line VPP for supplying the precharge voltage VP and each data line LDD.
In the first liquid crystal display panel of the present invention, the line boosting assisting means 11 is composed of a thin film transistor whose gate is controlled according to a data write signal WE.

The second liquid crystal display panel of the present invention is characterized in that the line boosting auxiliary means 11 is composed of a diode connected to an auxiliary power supply line VPP whose supply is controlled according to a data write signal WE. In the first and second liquid crystal display panels of the present invention, the auxiliary power supply line VPP is commonly connected to every several data lines LDD.

The control method of the liquid crystal display panel of the present invention is the control method of the active matrix type liquid crystal display panel having a plurality of data lines LDD connected to the thin film transistor 12 for applying the write voltage Vc to the pixel electrode 13. According to the write signal WE, first, the precharge voltage VP is supplied to each of the data lines LDD,
Then, the write voltage Vc is applied to the data line LDD.

In the liquid crystal display panel control method of the present invention, the precharge voltage VP is set higher than the write voltage Vc. The liquid crystal display device of the present invention,
A liquid crystal display panel that performs gradation display based on a voltage written in a pixel electrode, and a display driver that controls output of the display panel, wherein the display panel is one of the liquid crystal display panels of the present invention. The above-mentioned object is achieved.

[0017]

[Operation] The operation of the first liquid crystal display panel of the present invention will be described. When the data write signal WE is supplied to the line boosting auxiliary means 11 composed of, for example, a thin film transistor,
When the means 11 is turned on, the precharge voltage VP is supplied to the data line LDD.

Therefore, the potential of the data line LDD can be rapidly raised based on the precharge voltage VP, and the driving capability of the data driver 14 for applying the write voltage Vc to the pixel electrode 13 can be assisted. Become. As a result, even if the number of pixels is increased due to the demand for improving the image quality and display quality of the liquid crystal display device, the increase in the driving capability of the driver 14 can be suppressed to the necessary minimum.

As a result, it is possible to suppress an increase in power consumption inside the driver 14, reduce the power consumption of the liquid crystal display device, and prolong the duration of use of the battery-driven liquid crystal display device. It will be possible. The operation of the second liquid crystal display panel of the present invention will be described. For example, when the auxiliary power supply line VPP whose supply is controlled according to the data write signal WE is asserted, the precharge voltage VP is supplied to the data line LDD through the diode.

Therefore, the potential of the data line LDD can be rapidly raised on the basis of the precharge voltage VP, and like the first liquid crystal display panel, the driver 14 for applying the write voltage Vc to the pixel electrode 13 is driven. It becomes possible to assist the driving ability. As a result, similarly to the first liquid crystal display panel, the increase in the driving capability of the driver 14 can be suppressed to a necessary minimum, the increase in power consumption inside the driver 14 can be suppressed, and the liquid crystal display device It is possible to achieve low consumption. In addition, it is possible to extend the duration of use of the battery-driven portable device.

In the first and second liquid crystal display panels of the present invention, the auxiliary power supply line VPP is commonly connected to every several data lines LDD. For this reason, it is possible to reduce the number of electric wires to be connected to the external power source. According to the control method of the liquid crystal display panel of the present invention, the precharge voltage VP is supplied, and then the write voltage Vc is applied to the data line LDD.
Is applied.

Therefore, even if the number of pixels is increased and the resistance value and the parasitic capacitance are increased due to the demand for improving the image quality and display quality of the liquid crystal display device and the time constant becomes large, the data line LDD is pulled in a short time. Therefore, the write voltage Vc of the data line LDD can be stabilized early. Thus, unlike the conventional example, the charging characteristic of the write voltage Vc to the pixel electrode 13 is not limited by the rising characteristic of the driver amplifier.

The operation of the liquid crystal display device of the present invention will be described.
For example, the data write signal WE is the line boosting assisting means 1
When supplied to 1, the precharge voltage VP is supplied to the data line L DD by turning on the means 11. Based on this, the potential of the data line LDD is suddenly raised. On the other hand, a pixel selection signal is output from the display driver to the TFT via the gate line LGG of the display panel, and in this state, the write voltage Vc is supplied from the operational amplifier of the display driver via the data line LGG, and T
When the FT turns on, the write voltage Vc changes to the pixel electrode 1
Written in 3.

Therefore, by supplying the precharge voltage VP, the driving capability of the display driver is assisted, and the display panel can quickly perform multi-gradation display based on the stable write voltage Vc. As a result, it is possible to improve the image quality and the display quality of the liquid crystal display device by increasing the number of pixels while suppressing the increase in the driving capability of the driver to a necessary minimum and reducing the power consumption. Become.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, each embodiment of the present invention will be described with reference to the drawings. 2 to 5 are diagrams illustrating a liquid crystal display panel, a control method thereof, and a liquid crystal display device according to an embodiment of the present invention. (1) Description of First Embodiment FIG. 2 is a configuration diagram of a liquid crystal display device according to a first embodiment of the present invention, and FIG. 3 is a relational diagram between a data write signal and a signal waveform of a data line. Are shown respectively. For example, a liquid crystal display device including an active matrix liquid crystal display panel having a data line auxiliary boosting function includes a liquid crystal display panel 21, an analog driver 24, and a gate driver 25, as shown in FIG.

The liquid crystal display panel 21 includes a plurality of line boosting thin film transistors (referred to as TFTs) 23 and a pixel selecting T.
The FT 12 and the pixel electrode 13 are provided, and gradation display is performed based on the voltage Vc written in the pixel electrode 13.
The panel 21 is the first liquid crystal display panel of the present invention. The line boosting TFT 23 is a line boosting auxiliary means 1
This is an example of No. 1 and supplies the precharge voltage VP to the data line L DD according to the data write signal WE. The precharge voltage VP is set higher than the write voltage Vc.
The TFT 23 is connected between each data line LDD and the auxiliary power supply line VPP that supplies the precharge voltage VP. The TFT 23 is composed of, for example, an n-type field effect transistor, and is turned on when the signal WE = “H” (high) level and turned off when it is “L” (low) level. The TFT 23 is formed simultaneously with the pixel selection TFT 12.

The auxiliary power supply line VPP is composed of several data lines L.
Commonly connected for each DD. For example, four data lines LDD are connected at the upper part of the display panel to make one line, and the lines are led out to the outside. This reduces the number of drawers. In addition, by pulling out the data line LDD above and below the display panel 21,
The line drawn to the upper side and the line drawn to the lower side have opposite polarities. Therefore, the data write signal WE
Also has two types with different phases. As a result, the signal WE
The signal line of can also be divided into two blocks of an upper lead-out portion and a lower lead-out portion to form a common line.

The pixel selection TFT 12 controls the supply of the write voltage Vc to the pixel electrode 13. The drain of the TFT 12 is connected to the data line LDD, the source thereof is connected to the pixel electrode 13, and the gate thereof is the gate line L.
Connected to GG respectively. The pixel electrode 13 charges the data write voltage Vc. For example, in the case of color display, the display panel 21 has 640 lines × 480 rows ×
Three (R, G, B) pixel electrodes 13 are provided.

The analog driver 24 and the gate driver 25 form a display driver and control the output of the liquid crystal display panel 21. The analog driver 24 is connected to the data lines LDD drawn above and below the display panel 21. For example, the upper analog driver 24 supplies the write voltage Vc to the TFTs 12 connected to the even-numbered data lines LDD. The lower analog driver 24 supplies the write voltage Vc to the TFT 12 connected to the odd-numbered data line LDD. The gate driver 25 selects the TFT 12 connected to the gate line LGG.

Next, regarding the control method of the liquid crystal display panel according to the embodiment of the present invention, the operation of the display device will be described. For example, at the beginning of one horizontal period, the data write signal W
When E = “H” (high) level is supplied to the line boosting TFT 23, the TFT 23 is turned on to supply the precharge voltage VP to the data line L DD. Based on this, the potential of the data line LDD is suddenly raised. After that, the pixel selection signal is asserted from the gate driver 25 via the gate line LGG of the display panel 21, and in this state, the write voltage Vc is supplied from the operational amplifier 22 of the analog driver 24 via the data line LDD, and the TFT 12 is turned on. To work. As a result, the write voltage Vc is written in the pixel electrode 13.

In this way, according to the liquid crystal display device of the first embodiment of the present invention, as shown in FIG. 2, the liquid crystal display panel 21, the analog driver 24 and the gate driver 25 are provided, and the display panel concerned is provided. 21, the precharge voltage V is applied to the data line L DD according to the data write signal WE.
A line boosting TFT 23 for supplying P is provided. Therefore, the potential of the data line LDD can be rapidly raised based on the precharge voltage VP, and the pixel electrode 1
It is possible to assist the driving capability of the amplifier 22 of the analog driver 24 that applies the write voltage Vc to 3. Further, the liquid crystal display panel 21 can perform multi-gradation display based on the stable writing voltage Vc at an early stage.

As a result, the increase in the driving capability of the driver can be suppressed to the necessary minimum, and the power consumption can be reduced.
By increasing the number of pixels, it is possible to improve the image quality and display quality of the liquid crystal display device. Further, according to the control method of the liquid crystal display panel according to the embodiment of the present invention, the precharge voltage V higher than the write voltage Vc is first applied to each data line LDD in response to the data write signal WE.
P is supplied, and then the write voltage Vc is applied to the data line LDD.

Therefore, even if the number of pixels is increased and the resistance value and the parasitic capacitance are increased due to the demand for improving the image quality and the display quality of the liquid crystal display device and the time constant becomes large, as shown in FIG. , The waveform is rapidly raised by the precharge voltage VP, and the write voltage Vc can be made to depend on the rising characteristic of the analog driver 24 later. Note that FIG.
Shows the relationship between the pulse width Δt of the WE signal and the signal waveform of the data line LDD. In FIG. 3 (A), by setting the optimum pulse width Δt1 of the WE signal, the write voltage Vc of the data line LDD rises sharply as compared with the waveform rising of the conventional example.

Further, as shown in FIG. 3B, when a pulse width Δt2 longer than Δt1 is set, the signal waveform of the data line LDD overshoots. In this case, the rising characteristics of the analog drivers 23 and 24 can be assisted, and the time required to reach a predetermined voltage can be shortened.
On the contrary, as shown in FIG. 3C, when the pulse width Δt3 is set shorter than the pulse width Δt1, the signal waveform of the data line LDD depends largely on the rising characteristics of the amplifier 22 of the analog drivers 23 and 24.

By thus optimally setting the pulse width Δt1 of the WE signal, the data line LDD can be pulled up in a short time, and the write voltage Vc of the data line LDD can be stabilized early. Become. As a result, as in the conventional example, the amplifier 22 of the analog driver 24
Due to the rising characteristic of, the charging time of the writing voltage Vc to the pixel electrode 13 is not limited.

As a result, an increase in power consumption inside the analog driver 24 can be suppressed, the liquid crystal display device can be made low in power consumption, and the duration of use of the battery-driven liquid crystal display device can be extended. Is possible. Also, according to the first embodiment of the present invention, the auxiliary power supply line VPP is commonly connected to every several data lines. For this reason, it is possible to reduce the number of electric wires to be connected to the external power source.

(2) Description of Second Embodiment FIG. 4 is a configuration diagram of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 5 is an internal configuration diagram of the power supply control circuit thereof. Shows. The second embodiment is different from the first embodiment in that the line boosting auxiliary means 11 for precharging the data line LDD comprises a line boosting diode 32.

That is, the liquid crystal display device using the second liquid crystal display panel of the present invention, as shown in FIG. 4, has a liquid crystal display panel 31, a power supply control circuit 33, and an analog driver 24.
And a gate driver 25. Liquid crystal display panel 31
Is a plurality of line boosting diodes 32, pixel selection TF
T12 and the pixel electrode 13 are provided, and gradation display is performed based on the voltage Vc written in the pixel electrode 13. The panel 31 is the second liquid crystal display panel of the present invention.

The line boosting diode 32 is another example of the line boosting assisting means 11 and includes a data write signal WE.
According to the precharge voltage VP1,
Supply VP2. Precharge voltages VP1 and VP2
Is set to be higher than the voltage added with the quasi-directional voltage of the diode. The diode 32 is connected to the auxiliary power supply line VPP1 which supplies the precharge voltage VP1 to the odd data line LDD and to the even data line LDD.
It is connected to an auxiliary power supply line VPP2 that supplies P2. The diode 32 is formed simultaneously with the pixel selection TFT 12.

The power supply control circuit 33 is, for example, as shown in FIG.
As shown in FIG. 3, it has pnp-type and npn-type bipolar transistors Q1 and Q2 and bias resistors R1 and R2.
The function of the circuit 33 is that when the data write signal WE is supplied to the transistor Q2, the bias voltage divided by the resistors R1 and R2 is supplied to the transistor Q1. As a result, the transistor Q1 is turned on to output the precharge voltage VP1 or VP2 from the auxiliary power supply line VPP to the auxiliary power supply line VPP1 or VPP2.

As another configuration of the power supply control circuit 33A, for example, as shown in FIG. 5B, it has two analog switch elements SW1 and SW2 and an inverter INV1. The function of the circuit 33A is, for example, that of the circuit 33A.
When the data write signal WE = “H” level is input to A, the switch element SW1 is turned on and SW2 is turned off.
To work. Further, when WE becomes "L" level, the switch element SW2 is turned on and SW1 is turned off. As a result, during the WE = “H” level period, the precharge voltage VP1 or VP2 is set to the auxiliary power supply line VPP1 or VPP1.
Can be output to PP2. Note that the same symbols and names as those in the first embodiment have the same functions, and therefore their explanations are omitted.

Next, the operation of the liquid crystal display device according to the second embodiment of the present invention will be described. For example, when the data write signal WE = “H” level is supplied to the power supply control circuit 33 at the beginning of one horizontal period, the auxiliary power supply lines VPP1 and VPP2 are asserted and the precharge voltage VP1 is applied to the data line LDD through the diode 32. , VP2 are supplied. Based on this, the potential of the data line LDD is suddenly raised. After that, a pixel selection signal is asserted from the gate driver 25 via the gate line LGG of the display panel 31, and in this state, the operational amplifier 2 of the analog driver 24
The write voltage Vc is supplied from 2 through the data line LDD, and the TFT 12 is turned on. As a result, the write voltage Vc is written in the pixel electrode 13.

As described above, according to the liquid crystal display device of the second embodiment of the present invention, the liquid crystal display panel 31 having the plurality of line boosting diodes 32 and the diode 3 are provided.
2 is provided with a power supply control circuit 33 that supplies precharge voltages VP1 and VP2. Therefore, the potential of the data line LDD can be rapidly raised on the basis of the precharge voltages VP1 and VP2, and like the first embodiment.
It is possible to assist the driving capability of the analog driver 24 that applies the write voltage Vc to the pixel electrode 13. As a result, even if the number of pixels is increased due to the demand for improving the image quality and display quality of the liquid crystal display device, the increase in the driving capability of the amplifier 22 can be suppressed to the necessary minimum.

As a result, similarly to the first embodiment, it is possible to suppress an increase in power consumption inside the analog driver 24 and to reduce the power consumption of the liquid crystal display device.
It is possible to extend the duration of use of the battery-driven portable device. In each of the embodiments of the present invention, the case where the analog driver is used as the display driver has been described, but the line boosting function of the present invention can be applied even when the digital driver is used. The amplifier driving capability of the reference power supply that supplies the reference voltage to the digital driver can be reduced, which contributes to lower consumption of bias current and the like.

[0045]

As described above, according to the liquid crystal display panel of the present invention, the line boosting auxiliary means for supplying the precharge voltage to the data line according to the data write signal is provided. Therefore, the potential of the data line can be rapidly raised based on the precharge voltage, and the driving capability of the driver that applies the write voltage to the pixel electrode can be assisted.

According to the liquid crystal display panel control method of the present invention, the precharge voltage is first supplied to each data line in accordance with the data write signal, and then the write voltage is applied to the data line. Therefore, even if the resistance value and the parasitic capacitance increase as the number of pixels increases and the time constant increases, the data line can be pulled up in a short time, and the write voltage of the data line can be stabilized early. It becomes possible. This prevents the charging time of the write voltage to the pixel electrode from being limited by the rising characteristics of the driver amplifier as in the conventional example.

According to the liquid crystal display device of the present invention, the liquid crystal display panel comprises any one of the liquid crystal display panels of the present invention. Therefore, the driving capability of the display driver is assisted by the supply of the precharge voltage, and the display panel can execute the multi-gradation display based on the stable writing voltage at an early stage.

This greatly contributes to the provision of a liquid crystal display device of low power consumption type and the provision of a high pixel, high quality and high definition liquid crystal display and the like.

[Brief description of drawings]

FIG. 1 is a principle diagram of a liquid crystal display panel and a control method thereof according to the present invention.

FIG. 2 is a configuration diagram of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 3 is a relationship diagram between a WE signal and a signal waveform of a data line according to each embodiment of the present invention.

FIG. 4 is a configuration diagram of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a power supply control circuit according to a second embodiment of the present invention.

FIG. 6 is a waveform diagram of a liquid crystal display panel and a data line according to a conventional example.

[Explanation of symbols]

 11 ... Line boosting auxiliary means, 12 ... Thin film transistor (pixel selection TFT), 13 ... Pixel electrode, 14 ... Data driver, 23 ... Line boosting TFT, 24 ... Analog driver, 25 ... Gate driver, 32 ... Line boosting diode , 33 ... Power supply control circuit, VPP ... Auxiliary power supply line, WE ... Data write signal, Vc ... Write voltage, LDD ... Data line.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Kishida 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (8)

[Claims] 1. In an active matrix type liquid crystal display panel having a plurality of data lines connected to a thin film transistor for applying a write voltage to a pixel electrode, a line for supplying a precharge voltage to the data line according to a data write signal. A liquid crystal display panel comprising boosting auxiliary means. 2. The liquid crystal display panel according to claim 1, wherein the line boosting auxiliary means is connected between an auxiliary power supply line for supplying the precharge voltage and each of the data lines. 3. The liquid crystal display panel according to claim 1, wherein the line boosting assisting means comprises a thin film transistor whose gate is controlled according to a data write signal. 4. The liquid crystal display panel according to claim 1, wherein the line boosting auxiliary means is composed of a diode connected to an auxiliary power supply line whose supply is controlled according to a data write signal. 5. The liquid crystal display panel according to claim 2, wherein the auxiliary power line is commonly connected to every several data lines. 6. A method of controlling an active matrix type liquid crystal display panel having a plurality of data lines connected to a thin film transistor for applying a write voltage to a pixel electrode, wherein each of the data lines is first responded to in response to a data write signal. A method for controlling a liquid crystal display panel, comprising: applying a precharge voltage to the data line, and then applying a write voltage to the data line. 7. The method of controlling a liquid crystal display panel according to claim 6, wherein the precharge voltage is higher than a write voltage. 8. A liquid crystal display panel that performs gradation display based on a voltage written in a pixel electrode, and a display driver that controls output of the display panel, wherein the display panel comprises:
A liquid crystal display device comprising the liquid crystal display panel according to claim 1.