KR102234095B1 - Liquid crystal display device integrated with touch screen - Google Patents

Abstract

The present invention relates to a touch screen-integrated liquid crystal display device that prevents a defect in a gate driving signal caused by driving a display and driving a touch in a time-division manner.

Description

Liquid crystal display device with integrated touch screen {LIQUID CRYSTAL DISPLAY DEVICE INTEGRATED WITH TOUCH SCREEN}

The present invention relates to a liquid crystal display device, and more particularly, to a touch screen-integrated liquid crystal display device that prevents a defect in a gate driving signal caused by driving a display and driving a touch in a time-division manner.

A liquid crystal display device includes a liquid crystal panel on which an image is displayed, a backlight unit supplying light to the liquid crystal panel, and a driving circuit unit for driving the liquid crystal panel and a backlight (light source). The driving circuit unit includes a timing controller, a data driver, a gate shift register (gate driver), a backlight driver, and a power supply unit.

Amorphous silicon (a-Si) is used to form a thin film transistor (TFT) for driving each pixel on a lower substrate (TFT array substrate) of a liquid crystal panel, and a gate shift resistor is integrated on the lower substrate of the liquid crystal panel. GIP (Gate In Panel) method is applied. In this case, the gate shift register may be formed in the left/right non-display area of the lower substrate.

1 is a diagram showing a gate shift register according to the prior art.

Referring to FIG. 1, a first stage group 10 (odd stages) for supplying a gate driving signal to an odd-numbered gate line may be formed in a left non-display area of a lower substrate. In addition, a second stage group (even stages) for supplying a gate driving signal to an even-numbered gate line may be formed in a right non-display area of the lower substrate.

In FIG. 1, the first stage group 10 is shown among the gate shift registers, and the second stage group is not shown. The positions of the first stage group 10 and the second stage group may be interchanged.

For example, when 800 gate lines are formed in the active region, the first stage group 10 and the second stage group are each formed to include 400 stages.

2 is a diagram showing input and output waveforms of a gate shift register according to the prior art.

Referring to FIG. 2, a touch screen-integrated liquid crystal display device performs display driving and touch driving in a time division method. In this case, in order to increase the touch sensing performance, a method of performing touch sensing driving several times during one frame period is applied. After supplying a gate driving signal in units of a predetermined number of gate lines among all gate lines, touch driving is performed to perform touch sensing driving several times during one frame period.

Before Gate(N) output, the Q(N) node is precharged with the Gate(N-1) output, and the Gate(N) is output to the corresponding gate line in accordance with the Gate(N) output timing. Charge the Q(N+1) node. While performing this repeatedly, the gate driving voltage (scan signal) is output.

In the conventional liquid crystal display device integrated with a touch screen, a touch driving time is inserted in the middle of an output timing of a gate driving voltage while applying a time division type display driving and a touch driving. For this reason, the output of the gate driving voltage is maintained at VGL during the touch driving time.

As described above, while the output of the gate driving voltage is maintained at VGL during the touch driving time, a problem of a leakage current of the Q node of the corresponding stage occurs. Accordingly, there is a problem in that the gate output of the corresponding stage is lower than that of other stages, the rising time of the gate driving signal is increased, or a VGH voltage lower than the reference voltage is output, resulting in a screen defect.

The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a touch screen integrated liquid crystal display device that prevents defects in gate driving signals caused by display driving and touch driving in a time-division method.

In addition to the technical problems of the present invention mentioned above, other features and advantages of the present invention will be described below or will be clearly understood by those of ordinary skill in the art from such technology and description.

In the liquid crystal display device integrated with a touch screen according to an embodiment of the present invention, a plurality of gate output stages supply gate driving signals to a plurality of gate lines formed on the liquid crystal panel during a display driving period in one frame period, and a plurality of dummy stages Outputs an output signal as a start signal of a next stage during the touch driving period of the one frame period, and the output lines of the plurality of dummy stages are connected to the input terminal of the start signal of the next stage.

The liquid crystal display device with an integrated touch screen according to an exemplary embodiment of the present invention can prevent a defect in a gate driving signal caused by driving the display and driving the touch in a time-division manner.

In addition, other features and advantages of the present invention may be newly recognized through embodiments of the present invention.

1 is a diagram showing a gate shift register according to the prior art.
2 is a diagram showing input and output waveforms of a gate shift register according to the prior art.
3 is a diagram illustrating a touch screen-integrated liquid crystal display device according to an embodiment of the present invention.
4 is a diagram illustrating a gate shift register according to an embodiment of the present invention.
5 is a diagram illustrating a design example of a gate shift register according to an embodiment of the present invention.
6 is a diagram illustrating input and output waveforms of a gate shift register according to an embodiment of the present invention.

Prior to the description with reference to the drawings, the liquid crystal display device is a TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode, FFS (Fringe Field Switching) mode according to a method of adjusting the arrangement of liquid crystal layers And various driving modes have been developed. In the liquid crystal display device according to an exemplary embodiment of the present invention, all of the TN, VA, IPS, and FFS modes may be applied without limitation to a mode for driving the liquid crystal layer, and other modes may also be applied.

Hereinafter, a touch screen-integrated liquid crystal display device will be described with reference to the accompanying drawings.

3 is a diagram illustrating a touch screen-integrated liquid crystal display device according to an embodiment of the present invention.

3, a liquid crystal display device according to an embodiment of the present invention includes a liquid crystal panel 100, a backlight unit (not shown) supplying light to the liquid crystal panel 100, the liquid crystal panel 100, and a light source. And a driving circuit for driving.

The liquid crystal panel 100 has pixels arranged in a matrix and displays an image according to supplied image data (data voltage). The liquid crystal panel 100 includes a lower substrate (TFT array substrate) and an upper substrate (color filter array substrate) opposingly bonded together, and a liquid crystal layer formed between the lower substrate and the upper substrate. The lower polarizing film is disposed on the rear surface of the lower substrate, and the upper polarizing film is disposed on the upper surface of the upper substrate.

The upper substrate includes a color filter for displaying a color image by converting light incident through a pixel of the lower substrate into color light.

The lower substrate includes N gate lines and M data lines. A pixel is defined by intersection of gate lines and data lines, and each pixel includes a TFT (Thin Film Transistor) and a storage capacitor Cst. Further, the liquid crystal panel 100 includes a pixel electrode that applies a data voltage to a pixel and a common electrode that applies a common voltage Vcom.

The TFT of each pixel is switched by the gate driving signal supplied through the gate line, and when the TFT is turned on, the data voltage supplied through the data line is supplied to the pixel.

The arrangement state of the liquid crystals in each pixel is changed by the electric field difference between the data voltage and the common voltage, and an image is displayed by adjusting the arrangement of the liquid crystals to adjust the transmittance of light incident from the backlight unit.

A certain number of pixels (for example, width 60 × height 64) is configured as a single touch electrode, and a plurality of touch electrodes are gathered to form a touch screen. Each touch electrode is configured by connecting a common electrode of a lower substrate, and each touch electrode is connected to a touch driver through a separately formed touch line (not shown).

In the touch panel 100, in an in-cell touch method, a pixel for display and a touch screen for touch detection are integrated with a touch screen. Accordingly, display driving and touch driving are temporally divided and driven.

During the display period of one frame period, a data voltage according to the image data is supplied to the pixel electrode of each pixel, and a common voltage Vcom is supplied to the common electrode to display an image. Meanwhile, during one frame period, during the non-display period, the common electrode is driven as a touch electrode to sense a user's touch.

In order to improve touch sensing performance, a method of performing touch sensing driving multiple times during one frame period is applied. The touch driving time is inserted in the middle of the output timing of the gate driving voltage. After supplying a gate driving signal in units of a predetermined number of gate lines among all gate lines, touch driving is performed to perform touch sensing driving several times during one frame period.

The driving circuit unit includes a main controller 400, a gate shift register 200 (a gate driver), a backlight driver (not shown), and a power supply unit (not shown).

Here, the main controller 400 includes a timing controller (T-con), a data driver, a backlight driver, and a touch driver on a substrate, and pads formed in the pad area of the liquid crystal panel 100 through a tape carrier package (TCP). Can be connected with.

The timing controller aligns the input video signal into R, G, and B video data in units of frames, and supplies the aligned R, G, and B video data to the data driver. In addition, the timing controller generates a gate control signal GCS for controlling the gate shift register 200 and a data control signal DCS for controlling the data driver using the input timing signal TS. The timing signal TS includes a data enable signal DE, a horizontal synchronization signal Hsync, a vertical synchronization signal Vsync, and a clock signal CLK.

The gate control signal GCS may include a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the like.

The data control signal (DCS) includes a source start pulse (SSP), a source sampling clock (SSC), a source output enable (SOE), and a polarity control signal (POL: Polarity). It may include.

The data driver converts the R, G, and B video data supplied from the timing controller into analog video data (data voltage) during the display driving period. Thereafter, a data voltage is supplied to each pixel through the data lines of the liquid crystal panel 100. In addition, the data driver generates a start signal (Vst), a clock (CLK), a driving voltage (VDD), and a reset signal (Vreset) for driving the GIP-type gate shift register 200 based on the control of the timing controller. , And supply the generated Vst, CLK, VDD, and Vreset signals to the gate shift register 200.

During the touch period, the touch driver supplies a touch driving signal to the touch electrodes formed on the liquid crystal panel, and senses the presence or absence of a user's touch and a touch position by sensing capacitance formed on each touch electrode.

The gate shift register 200 of the touch screen integrated liquid crystal display device of the present invention generates a gate driving signal Vout and supplies it to each of a plurality of gate lines formed in the active region. Consists of including.

The gate shift register 200 generates a gate driving signal Vout using input driving voltages VDD and VSS and start signals Vst, CLK, and Vreset signals, and is applied to the gate lines of the liquid crystal panel 100. It is supplied sequentially.

The gate shift register 200 is formed to be distributed to the left and right of the non-display area (pad area) of the lower substrate. The first stage group 210 of the gate shift register 200 is formed in the non-display area on the left side of the lower substrate. In addition, the second stage group 220 of the gate shift register 200 is formed in the right non-display area of the lower substrate. For example, 1/2 of the entire stage may be formed in each of the left and right non-display areas of the lower substrate.

4 is a diagram illustrating a gate shift register according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating an example of a design of a gate shift register according to an embodiment of the present invention.

4 illustrates a first stage group 210 among the gate shift registers. Since the second stage is formed in the same manner as the first stage 210, detailed drawings of the second stage are omitted.

Meanwhile, the gate shift register 200 may further include a level shifter for converting the output of the gate driving signal Vout into a swing width suitable for driving the thin film transistor.

The gate driving signal Vout is sequentially supplied to 1/2 of the gate lines formed in the active region of the liquid crystal panel 100 through the stages of the first stage group 210. In addition, the gate driving signal Vout is sequentially supplied to 1/2 of the plurality of gate lines formed in the active region of the liquid crystal panel 100 through the stages of the second stage group 220. .

In order to improve touch sensing performance, a method of performing touch sensing driving multiple times during one frame period is applied. The touch driving time is inserted in the middle of the output timing of the gate driving voltage. After supplying a gate driving signal in units of a certain number of gate lines among all gate lines, touch driving is performed to perform touch sensing driving several times during one frame period.

When 800 gate lines are formed in the active region, the gate shift register 200 includes the same number of channels, that is, 800 gate output stages so as to correspond to 800 gate lines. That is, each of the first stage group 210 and the second stage group 220 includes 400 gate output stages.

In addition, each of the first stage group 210 and the second stage group 220 includes a plurality of dummy stages to prevent an output error of the gate driving voltage from occurring during the touch driving period.

Here, each of the plurality of dummy stages is formed at a position of a stage corresponding to a point in time when display driving is finished and touch driving is started during one frame period.

For example, the display may be driven until a gate driving signal is supplied to the N-1 th gate line in one frame period, and then the first touch driving may be performed.

In this case, the gate output stages supplying the gate driving signal to the N-1 gate line from the first gate line are normally formed to be connected to the gate line.

On the other hand, after the N-1th stage that supplies the gate driving signal to the N-1th gate line, the first dummy stage is formed, and in the first dummy stage, the Vout output line is formed so that the output voltage is not supplied to the gate line. There is not.

After the first touch period is ended during one frame period, the display may be driven until a gate driving signal is supplied to the 2N-1 th gate line again, and then the second touch may be driven.

In this case, the gate output stages supplying the gate driving signal to the 2N-1 gate line from the N-th gate line are formed to be normally connected to the gate line.

Here, in the N-th gate output stage supplying the gate driving signal to the N-th gate line, the first dummy stage receives an output voltage as a start signal Vst. To this end, an output line is formed in the first dummy stage such that the output Vout is connected to the input terminal of the start signal Vst of the N-th gate output stage.

In addition, after the 2N-1th gate output stage that supplies the gate driving signal to the 2N-1th gate line, a second dummy stage is formed, and the second dummy stage has a Vout output line so that the output voltage is not supplied to the gate line. Not formed.

After the second touch period is ended during one frame period, the display may be driven until the gate driving signal is supplied to the 3N-1 th gate line again, and then the third touch may be driven.

As shown in FIGS. 4 and 5, a dummy stage is formed at a position of a stage corresponding to a point in time when display driving is ended and touch driving is started during one frame period. The touch screen integrated display device according to an embodiment of the present invention is a dummy that supplies a start signal Vst to the first gate output stage of the display driving period after the touch driving period so that the gate driving signal is normally output after the touch driving period. The stage was formed separately.

In FIGS. 4 and 5, the gate shift register 200 has been illustrated and described as including 800 stages, but this describes one of various embodiments. The number of stages formed in the gate shift register 200 may be changed according to the number of gate lines in the active region. That is, the number of stages of the gate shift register may be changed in connection with the resolution of the liquid crystal panel.

Here, the gate driving signals Vout are alternately output from the stages of the first stage group 210 and the stages of the second stage group 220 so that the gate driving signals ( Vout) is output.

Each of the first stage 210 and the second stage 210 uses an output signal Vout (a gate driving signal) of the N-th stage as a start signal Vst for starting driving of the N+1-th stage. In addition, the output signal Vout (gate driving signal) of the stage located at the N+1th stage is used as a reset signal Vreset for resetting the output signal of the Nth stage.

That is, the output of the previous stage can be used as the start signal Vst of the next stage, and the output of the next stage can be used as the reset signal of the previous stage. Although not shown in the drawing, one to two reset signal stages may be additionally formed at the last stage of the first stage group 210.

6 is a diagram illustrating input and output waveforms of a gate shift register according to an embodiment of the present invention.

Referring to FIG. 6, although the voltage of the output (Vst N) of the dummy stage in the touch driving period is lower than that of a general gate driving signal, the output voltages of Gate(N) and Gate(N+1) are normally output.

That is, the output Vst(N) of the dummy stage is lower than the output voltage of the general gate output stage, but the output line of the dummy stage is not connected to the gate line, so the low output voltage is not supplied to the gate line.

Since the output line of the dummy stage is not connected to the actual gate line, there is no output load. Therefore, the Q(N) node of the next stage can be sufficiently charged. Accordingly, the first gate driving signal (gate N) of the display driving period after the touch driving period can be normally output.

Those skilled in the art to which the present invention pertains will be able to understand that the above-described present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting.

The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100: liquid crystal panel
200: shift register
210: first stage group
220: second stage group

Claims (7)

In the touch screen integrated liquid crystal display device in which a gate shift register is formed in a non-display area of a liquid crystal panel,
A plurality of gate output stages supplying gate driving signals to a plurality of gate lines formed in the liquid crystal panel during a display driving period during one frame period; And
A plurality of dummy stages for outputting an output signal as a start signal of a next stage during a touch driving period in the one frame period; and
The output lines of the plurality of dummy stages are not connected to a gate line, but are connected only to an input terminal of a start signal of a next stage. The method of claim 1,
Each of the plurality of dummy stages is formed at a position of a stage corresponding to a point in time when the display driving period ends and the touch driving starts. The method of claim 1,
Each of the plurality of dummy stages supplies a start signal Vst to a first gate output stage in a display driving period after the touch driving period. The method of claim 1,
Of the plurality of gate output stages, each of the output lines of the first gate output stage to the N-th gate output stage is connected to the N-th gate line from the first gate line,
Among the plurality of dummy stages, a dummy stage formed between an N-th gate output stage and the N-th gate output stage is connected to an input terminal of a start signal of the N-th gate output stage. A liquid crystal panel including N gate lines and M data lines;
N gate output stages disposed in the non-display area of the liquid crystal panel and connected to each of a first gate line to an N-th gate line; And
It includes a dummy stage connected between the output line of the N-1th gate output stage and the input terminal of the start signal of the Nth gate output stage,
The dummy stage supplies a start signal to the N-th gate output stage during a touch driving period among one frame period. The method of claim 5,
The dummy stage is not connected to the N gate lines, a touch screen integrated liquid crystal display device. The method according to any one of claims 4 to 6,
Of the N gate output stages, each of the first gate output stage to the N-1th gate output stage applies a gate driving signal to each of the first gate line to the N-1th gate line during the display driving period during the one frame period. Supply,
The N-th gate stage supplies a gate driving signal to the N-th gate line during a display driving period after the touch driving period during the one frame period.

Images