JPH10123483A - Liquid crystal display device and its drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a sufficient charge neutralization time and to reduce power consumption in a source driver IC by using a gate driver capable of simultaneously driving plural gate lines and neutralizing liquid crystal charges on plural horizontal lines. SOLUTION: The data of a high level are read in an initial stage SR1 of a shift register 21 in the gate driver IC 12, and both output terminals of the gate lines G1, G2 output the high level through OR circuits OR1 , OR2 . Then, write-in into liquid crystal capacity C11 -C1n , C21 -C2n becomes possible. Thereafter, all output terminals of the source lines S1 -Sn of the source driver IC 11 output Vcom potential by a control signal of a timing control circuit 13, and perform electric neutralization of all liquid crystal capacity in two horizontal lines much. Thereafter, one pulse of CLK is inputted to the gate driver IC 12, and the data of the high level in the shift register 21 are shifted to SR2, and the high level is outputted to only the gate line G1 output terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active matrix type liquid crystal display device and a driving method thereof.

[0002]

2. Description of the Related Art The configuration of a conventional active matrix type liquid crystal display device (hereinafter referred to as TFT-LCD) is shown in FIG. That is, from the liquid crystal display panel 40, the source driver IC 41 for outputting a write voltage to the liquid crystal display panel 40, the gate driver IC 42 for performing line-sequential driving of horizontal lines, and the timing control circuit 43 for outputting control signals for these ICs. Has become
Each pixel of the liquid crystal display panel 40 has a thin film transistor (hereinafter, referred to as a TFT) Qm of a switch for preventing leakage of write charge of the liquid crystal capacitance Cmn.

The source driver IC according to the prior art has a function of outputting the common electrode potential Vcom of the liquid crystal display panel to all output terminals, and once neutralizes the total liquid crystal capacity of one horizontal line to the Vcom level. Then, a predetermined write voltage is applied, and this operation is performed on all horizontal lines. In general, the liquid crystal material needs to be driven by an alternating current to prevent burn-in. In particular, in a dot inversion drive in which the Vcom of the liquid crystal is fixed and the polarity of the voltage applied to the liquid crystal is inverted for each dot, the entire writing voltage of one horizontal line is reduced. Short-circuiting can reduce the current consumption of the source driver IC.

[0004] FIG. 7 shows a liquid crystal driving waveform in a TFT-LCD panel using this conventional technique. First, the gate is the gate voltage of the horizontal line G ₁ for writing driver I
C42 By goes high, 1 all TFTs Q ₁ horizontal line G ₁ to the ON state, a state capable of writing to the liquid crystal capacitor C ₁₁ -C _1n. Next, the source driver IC
All the source lines S ₁ to S _n from Vcom level 41 performs neutralization of the liquid crystal application voltage for one horizontal line all the dots are output, the horizontal line neutralization of all the pixels is completed, according to the display data again write Voltage is source driver IC41
Applied from the source line S ₁ to S _n. The wiring resistance R and the liquid crystal capacitor C ₁₁ -C _1n the neutralization time LCD panel
And it is determined by the output impedance of the source driver IC 41, and therefore differs for each panel. When writing is sufficiently performed by the source driver IC 41, the output of the gate driver IC 42 becomes low level, and the writing of one horizontal line is completed. Then, the next horizontal line G ₂
Becomes high level, and the next horizontal line is neutralized and the write operation is performed. In this manner, writing of all horizontal lines is performed, and writing of one frame is completed.

The source driver I in the prior art is
As shown in the equivalent circuit diagram of the source driver IC in FIG. 5, the output of the Vcom potential by C is determined by taking the Vcom potential supplied from the outside by a switch 51 that can be controlled from the outside in consideration of the current consumption of the IC as an output terminal. This is performed by short-circuiting inside the IC. Therefore, I within the neutralization time
It is possible to reduce power consumption by reducing the current consumption of C and reducing the output amplitude of the source driver IC by neutralization. FIG. 6 is an equivalent circuit diagram of a conventional gate driver IC.

[0006]

In the prior art, FIG.
As shown in (1), the neutralization time and the writing time of one horizontal line exist within the writing time allocated to one horizontal period. However, when the LCD panel has a large screen and high definition, the writing time assigned to one horizontal line becomes shorter, and the load capacity of each dot of the liquid crystal also increases, so that the time required for charging and discharging the liquid crystal capacity also increases. Therefore, it is very difficult to provide a time for neutralizing a horizontal line in the writing time allocated to one horizontal line.

Accordingly, an object of the present invention is to use a gate driver IC capable of driving a plurality of lines to neutralize the liquid crystal charge which has been performed on all the horizontal lines until now, by using a plurality of lines of the liquid crystal for each of the plurality of horizontal lines. An object of the present invention is to provide a liquid crystal display device capable of neutralizing liquid crystal charge in a large-screen, high-definition LCD panel, which is performed on pixels.

[0008]

According to the present invention, a liquid crystal display panel, a source driver IC having a function of outputting a common electrode potential of the liquid crystal display panel to all output terminals, and a function of simultaneously driving a plurality of horizontal lines are provided. Driver IC having
And the source driver IC and the gate driver I
A liquid crystal display device including a timing control circuit for controlling C is obtained. The gate driver IC is
It has a shift register having a bit number of 1.5 times the number of outputs, and an OR circuit of the same number as the number of outputs provided in the final stage of output.

Also, according to the present invention, the gate driver I
C. A method for driving an active matrix type liquid crystal display device in which horizontal lines of a liquid crystal display panel are sequentially selected by a signal from C, a neutralizing voltage is applied to each pixel from a source driver IC, and then a predetermined writing voltage is applied. A method of driving a liquid crystal display device in which the horizontal line is simultaneously selected, the neutralizing voltage is applied to each pixel at the same time, and then the operation of sequentially applying the write voltage to the pixels of each horizontal line is sequentially repeated for a plurality of horizontal lines. can get.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an LCD device according to an embodiment of the present invention, which is the same in appearance as a conventional configuration diagram, except that the specific configuration of the gate driver IC is different from that of the conventional one shown in FIG. Is different. FIG. 2 shows an equivalent circuit diagram of the gate driver IC 12 according to the present invention. Here, an equivalent circuit diagram of a gate driver IC capable of simultaneously driving two lines is shown. In order to enable simultaneous driving of two outputs, a shift register 21 having a bit number 1.5 times the number of outputs is provided. The output last stage has an OR circuit OR. FIG. 3 shows driving waveforms when panel driving is performed under these configurations.

Next, the driving method will be described. First, the first stage SR1 of the shift register 21 of the gate driver IC 12 is described.
High level data is read into the OR circuit OR ₁ ,
Through the OR ₂ both output terminals of the gate lines G1, G2 outputs a high level. As a result, all the TFTs Q ₁ and Q ₂ corresponding to two horizontal lines are turned on, and the liquid crystal capacitance C ₁₁
To C _1n and C _{21 to} C _2n can be written. Thereafter, the control signal of the timing control circuit 13, the total output of the source lines S ₁ to S _n of the source driver IC11 outputs a Vcom potential for electrical neutralization of the total liquid crystal capacitance of the two horizontal lines. After the electrical neutralization is completed, one pulse of CLK is input to the gate driver IC 12 to shift high-level data in the shift register 21 to SR2, and output high-level only to the G1 output terminal. As a result, the TFT Q _{1 for} one horizontal line is turned on, and writing of the first horizontal line is performed by the source driver IC 11 which has received the control signal from the timing control circuit 13. Further, when another pulse of CLK is input to the gate driver IC 12, only the G2 output terminal becomes high level, and the writing of the second horizontal line is performed. This operation is performed successively after the next horizontal line, and the writing of one frame is completed.

As described above, in the present invention, the electric neutralization of the liquid crystal capacitance is performed every two lines, so that even if the LCD panel has a large screen and high definition, a time for performing the electric neutralization is secured. It is possible to do.

[0013]

As described above, the present invention uses a gate driver capable of simultaneously driving a plurality of gate lines,
By performing liquid crystal charge neutralization on a plurality of horizontal lines, it is possible to secure a sufficient charge neutralization time even on a large-screen, high-definition LCD panel, and reduce the output amplitude of the source driver IC. Thereby, the power consumption of the source driver IC can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 shows a gate driver I according to an embodiment of the present invention.
It is an equivalent circuit diagram of C.

FIG. 3 is a diagram showing driving waveforms according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional liquid crystal display device.

FIG. 5 is an equivalent circuit diagram of a conventional source driver IC.

FIG. 6 is an equivalent circuit diagram of a conventional gate driver IC.

FIG. 7 is a diagram showing driving waveforms based on a conventional liquid crystal display device.

[Explanation of symbols]

10,40 liquid crystal display driver 11, 41 the source driver IC 12, 42 a gate driver IC 13, 43 timing control circuit _{Q 1 ~Q m TFT G 1 ~G} m horizontal lines gate electrode C ₁₁ -C _mn liquid crystal capacitor S ₁ to S _n source driver electrode 22 level shifter OR _{1 to} OR ₁₂₀ OR circuit

Claims (3)

[Claims] 1. A liquid crystal display panel, a source driver IC having a function of outputting a common electrode potential of the liquid crystal display panel to all output terminals, a gate driver IC having a function of simultaneously driving a plurality of horizontal lines, and the source driver ICs And a timing control circuit for controlling the gate driver IC. 2. The gate driver IC according to claim 1, further comprising: a shift register having a bit number of 1.5 times the number of outputs, and an OR circuit having the same number of outputs as the number of outputs provided in a final stage of the output. 2. The liquid crystal display device according to 1. 3. An active matrix liquid crystal display in which horizontal lines of a liquid crystal display panel are sequentially selected by a signal from a gate driver IC, a neutralization voltage is applied to each pixel from a source driver IC, and then a predetermined write voltage is applied. In the driving method of the apparatus, an operation of simultaneously selecting a plurality of horizontal lines, applying a neutralization voltage to each pixel at the same time, and sequentially applying a write voltage to the pixels of each horizontal line is sequentially repeated for each of the plurality of horizontal lines. A method for driving a liquid crystal display device, comprising: