KR101548493B1 - Liquid crystal display device - Google Patents

Abstract

The present invention relates to a liquid crystal display capable of providing a user interface function as well as a display function of an image by incorporating a sensor unit for detecting an incident light ray to each pixel. The liquid crystal display device includes a plurality of pixels arranged in a matrix Wherein each of the plurality of pixels includes a pixel voltage supplied to the data line in response to a display gate signal supplied to the display gate line and a pixel voltage supplied to the data line in response to a display gate signal supplied to the display gate line, A display unit for displaying the image by adjusting a light transmittance according to a common voltage supplied to the common electrode; And a photodetector for generating a photocurrent corresponding to the incident light and outputting a sensing signal corresponding to the generated photocurrent in response to the display gate signal supplied to the display gate line, And a sensor unit reset by a sensor reset voltage supplied to the data line according to a gate signal.

Display part, sensor part, photocurrent, sensing signal, reset voltage, blanking

Description

[0001] LIQUID CRYSTAL DISPLAY DEVICE [0002]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which a sensor portion for detecting an incident light beam is incorporated in each pixel to provide a user interface function as well as an image display function.

Typically, a liquid crystal display displays a desired image by applying a pixel voltage to a plurality of pixels arranged in a mattress shape to adjust a light transmittance of a pixel.

Each of the plurality of pixels includes a thin film transistor T connected to the gate line GL and the data line DL and a liquid crystal capacitor Clc connected to the thin film transistor T, And a storage capacitor Cst.

The liquid crystal capacitor Clc is composed of a pixel electrode connected to the thin film transistor T and a common electrode facing the pixel electrode with the liquid crystal therebetween. The liquid crystal capacitor Clc charges the difference between the pixel voltage supplied to the pixel electrode and the common voltage Vcom supplied to the common electrode, and adjusts the light transmittance of the liquid crystal in accordance with the difference voltage.

The storage capacitor Cst maintains the voltage charged in the liquid crystal capacitor until the next pixel voltage is supplied.

Such a liquid crystal display device including a plurality of pixels displays a predetermined image by adjusting the transmittance of light emitted from the backlight unit according to the pixel voltage and the electric field formed by the common voltage Vcom.

However, the conventional liquid crystal display device has a problem in that it can not provide other functions other than the function of displaying a predetermined image through the plurality of pixels described above.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device capable of providing a user interface function as well as a display function of an image by incorporating a sensor unit for detecting an incident light beam to each pixel .

According to an aspect of the present invention, there is provided a liquid crystal display device including a liquid crystal display panel that displays an image using light transmittance of each of a plurality of pixels arranged in a matrix, Each of the pixels includes a display unit for displaying the image by adjusting a light transmittance according to a pixel voltage supplied to the data line and a common voltage supplied to the common electrode in response to a display gate signal supplied to the display gate line; And a photodetector for generating a photocurrent corresponding to the incident light and outputting a sensing signal corresponding to the generated photocurrent in response to the display gate signal supplied to the display gate line, And a sensor unit reset by a sensor reset voltage supplied to the data line according to a gate signal.

The incident light may be a laser beam, an infrared ray, a visible ray, or an ultraviolet ray.

The liquid crystal display device may further include a backlight unit for emitting light to the liquid crystal display panel, and the timing control unit may apply a sensing signal supplied from the sensing signal receiver to the natural or artificial light incident on the liquid crystal display panel. The brightness of the backlight unit is adjusted according to the detected ambient illuminance.

As described above, the liquid crystal display device according to the present invention has the following effects by forming the display portion and the sensor portion in each pixel.

First, there is an effect that a user interface function can be performed in addition to a display function of an image by detecting an incident light ray according to a user's operation.

Second, it is possible to use the liquid crystal display panel as a touch screen by detecting the touch of the user through the sensor unit.

Thirdly, there is an effect that the power consumption can be reduced by detecting the ambient illuminance of the liquid crystal display panel through the sensing signal detected by the sensor unit and adjusting the brightness of the backlight unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view for explaining a liquid crystal display according to an embodiment of the present invention.

1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal display panel 100, a timing controller 200, a gate driver 300, a data driver 400, a sensing signal receiver 500, And a backlight unit (600).

The liquid crystal display panel 100 includes a plurality of pixels P arranged in a matrix and formed for each region defined by a plurality of display gate lines DGL1 to DGLn and a plurality of data lines DL1 to DLm .

Each of the plurality of pixels P includes a display unit 110 and a sensor unit 120 as shown in Fig.

The display section 110 includes a display thin film transistor DT connected to the display gate line GL and the data line DL and a liquid crystal capacitor Clc connected to the display thin film transistor DT, Cst).

The liquid crystal capacitor Clc is composed of a pixel electrode connected to the display thin film transistor DT and a common electrode facing the pixel electrode with the liquid crystal therebetween. The liquid crystal capacitor Clc charges the difference between the pixel voltage supplied to the pixel electrode and the common voltage Vcom supplied to the common electrode, and adjusts the light transmittance of the liquid crystal in accordance with the difference voltage.

The storage capacitor Cst maintains the voltage charged in the liquid crystal capacitor until the next pixel voltage is supplied.

The display unit 110 displays a predetermined image by adjusting the light transmittance according to the pixel voltage supplied to the data lines DL1 to DLm in response to the display gate signal supplied to the display gate lines DGL1 to DGLn do.

The sensor unit 120 includes a sensor thin film transistor ST, a sensor capacitor C, and first and second thin film transistors S1 and S2.

The sensor thin film transistor ST is connected to the sensor gate line SGL and the data line DL. When the sensor thin film transistor ST is turned off by the sensor gate signal supplied to the sensor gate line SGL, as shown in FIG. 3, Depending on the characteristics of the transistor, a photocurrent corresponding to the incident light is generated. Here, the incident light may be any one of a laser, an infrared ray, a visible ray, and an ultraviolet ray, and preferably a laser ray having a color that the user can identify.

On the other hand, the sensor thin film transistor ST is reset by the sensor reset voltage supplied to the data line DL when it is turned on by the gate signal for the sensor supplied to the sensor gate line SGL .

Meanwhile, the sensor thin film transistor ST may detect the incident light as well as the touch of the user by generating a photocurrent corresponding to the change of the incident light ray when the user touches the liquid crystal display panel 100. In this case, the liquid crystal display panel 100 can perform not only a display function of an image but also a touch screen function.

The capacitor C for the sensor is formed between the thin film transistor ST for the sensor and the common electrode. The sensor capacitor C stores the optical voltage corresponding to the photocurrent according to the difference between the photocurrent generated when the sensor thin film transistor ST is turned off and the common voltage supplied to the common electrode, And switches the second thin film transistor S2 according to the voltage. On the other hand, the sensor capacitor C is reset by the sensor reset voltage supplied from the sensor thin film transistor ST when the sensor thin film transistor ST is turned on.

The first thin film transistor S1 is connected to the display gate line DGL and the driving power line VDDL and supplies the driving voltage VDD supplied from the driving power line VDDL according to the display gate signal, And supplies it to the transistor S2. Here, the driving power supply line VDDL may be formed to be parallel to the data line DL.

On the other hand, the first thin film transistor S1 may be supplied with a common voltage, which is electrically connected to the common electrode and is supplied to the common electrode without the driving power supply line VDDL provided separately. In this case, since the area occupied by the driving power supply line VDDL in the pixel P can be eliminated, it is preferable that the first thin film transistor S1 is electrically connected to the common electrode.

The second thin film transistor S2 is connected to the first thin film transistor DT and the sensing signal output line SSL so that the light voltage stored in the sensor capacitor C and the driving voltage Vcc supplied from the first thin film transistor S1 VDD), thereby outputting a sensing signal corresponding to the optical voltage to the sensing signal output line SSL.

The sensor unit 120 generates a photocurrent corresponding to the incident light and outputs a sensing signal corresponding to the photocurrent in response to a display gate signal supplied to the display gate line DGL, Reset by the sensor reset voltage supplied to the data line DL in at least one frame unit in response to the gate signal for the sensor supplied to the scan line SGL, Detects the surrounding external illuminance and outputs it to the sensing signal output line (SSL).

Such a liquid crystal display panel 100 displays a predetermined image using the display unit 110 formed on each pixel P and uses the sensor unit 120 formed on each pixel P And outputs the detected light to the outside, thereby performing not only the image display function but also the user interface function.

1, the timing controller 200 aligns the data signal RGB input from the outside to be suitable for driving the liquid crystal display panel 100, supplies the data signal to the data driver 400, TSS to generate a gate control signal GCS for controlling the driving timing of the gate driving unit 300 and a data control signal DCS for controlling the driving timing of the data driving unit 400. [

The timing control signal TSS may be a data enable DE, a dot clock DCLK, a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, or the like. The data control signal DCS may be a source start pulse, a source sampling clock, a source output enable, and a polarity control signal POL. The gate control signal GCS includes a gate start pulse (GST), a gate shift clock (Gate Shift Clock), and a gate output signal (gate output signal) for sequentially generating gate pulses and supplying them to the plurality of gate lines GL1 to GLn. (Gate Output Enable) or the like.

The timing control unit 200 generates a sensor reset signal for resetting the sensor unit 120 of each pixel P during a blanking interval between frames and frames by at least one frame unit using the vertical synchronization signal Vsync, And generates a control signal. Here, the sensor reset control signal may have a first logic state during a blanking period in at least one frame unit, and a second logic state during a remaining operation except for the blanking period.

Meanwhile, the timing controller 200 performs a user interface function by transmitting the sensing signal SS supplied from the sensing signal receiver 500 to the outside.

On the other hand, the timing controller 200 uses the sensing signal SS supplied from the sensing signal receiver 500 to adjust the ambient illuminance of the liquid crystal display panel 100 according to the natural or artificial light incident on the liquid crystal display panel 100 And generates a dimming signal DIM for adjusting the luminance of the backlight unit 600 according to the detected ambient illuminance.

The gate driver 300 generates a display gate signal in response to a gate control signal GCS supplied from the timing controller 200 and supplies the generated display gate signal to a plurality of display gate lines (DGL1 to DGLn).

The gate driver 300 generates a gate signal for the sensor during the blanking interval in units of frames at least one frame in response to the gate control signal for the sensor supplied from the timing controller 200 and supplies it to the plurality of sensor gate lines SGL1 to SGLn, Sequentially or simultaneously.

The data driver 400 generates a pixel voltage corresponding to the data signal supplied from the timing controller 200 in response to the data control signal DCS supplied from the timing controller 200, And supplies them to the plurality of data lines DL1 to DLm in the horizontal interval unit during the display period.

In addition, the data driver 400 generates a sensor reset voltage in response to a sensor reset control signal supplied from the timing controller 200, and supplies the sensor reset voltage to the plurality of data lines DL1 to DLm during a blanking period in units of at least one frame.

To this end, the data driver 400 includes a pixel voltage generator 410 and a voltage output unit 420, as shown in FIG.

The pixel voltage generating unit 410 generates pixel voltages PV1 to PVm corresponding to the data signals R, G, and B supplied from the timing controller 200 under the control of the timing controller 200, (420). The pixel voltage generator 410 includes a signal controller 411, a gamma voltage generator 413, a digital processor 415, and an analog processor 417.

The signal controller 411 relays the data control signals SSP, SSC, SOE, and POL supplied from the timing controller 200 and the data signals R, G, and B to be output to the corresponding components.

The gamma voltage generator 413 supplies a plurality of reference gamma voltages GMA supplied from the outside to a plurality of positive gamma voltages PGV corresponding to the total number of gradations of the data signals R, (NGV), and supplies a plurality of subdivided positive polarity gamma voltages (PGV) and a plurality of negative polarity gamma voltages (NGV) to the analog processing section 417.

The digital processing unit 415 generates a sequential sampling signal using the source start pulse SSP and the source shift signal SSC supplied from the signal control unit 411 and outputs the sequential sampling signal from the signal control unit 411 Sequentially outputs the data signals R, G, and B latched in accordance with the source output enable signal SOE to the analog processing unit 417.

The analog processing unit 417 uses the plurality of positive polarity gamma voltages PGV and the plurality of negative polarity gamma voltages NGV supplied from the gamma voltage generating unit 413 to generate a data signal R, G and B are converted into analog pixel voltages of positive and negative polarity and then the analog pixel voltages PV1 to PV3 of positive or negative polarity are output in accordance with the polarity control signal POL supplied from the signal controller 411, And outputs it to the voltage output unit 420. [

The voltage output unit 420 buffers the analog pixel voltages PV1 to PVm supplied from the analog processing unit 417 and supplies the analog pixel voltages PV1 to PVm in response to the sensor reset control signal SRCS supplied from the timing controller 200. [ And selectively supplies the voltages PV1 to PVm or the sensor reset voltage SRV to the corresponding data lines DL1 to DLm.

The voltage output unit 420 according to the first embodiment includes a plurality of buffers BUF and a plurality of selectors MUX as shown in Fig.

Each of the plurality of buffers BUF buffers the analog pixel voltages PV1 to PVm supplied from the analog processing unit 417 and supplies them to each of the plurality of selectors MUX.

Each of the plurality of selectors MUX selects one of the analog pixel voltages PV1 to PVm and the sensor reset voltage SRV according to the sensor reset control signal SRCS of the first logic state supplied from the timing controller 200, (SRV) to the plurality of data lines DL1 to DLm. Here, the sensor reset voltage SRV is a voltage for resetting the sensor capacitor C of the sensor unit 120 (see FIG. 2) formed in each pixel P, and is the same as the drive voltage VDD or the common voltage Vcom But may have an arbitrary voltage level supplied from the outside or the gamma voltage generating section 413. [

Each of the plurality of selectors MUX selects one of the analog pixel voltages PV1 to PVm and the sensor reset voltage SRV in accordance with the sensor reset control signal SRCS of the second logic state supplied from the timing controller 200, Pixel voltages PV1 to PVm are selected and supplied to the plurality of data lines DL1 to DLm.

The voltage output section 420 according to the second embodiment includes a plurality of buffers BUF and a plurality of switching elements SW as shown in Fig.

Each of the plurality of buffers BUF buffers the analog pixel voltages PV1 to PVm supplied from the analog processing unit 417 and supplies them to the plurality of data lines DL1 to DLm.

Each of the plurality of switching elements SW is electrically connected between the output terminals of the plurality of buffers BUF and is turned on according to the sensor reset control signal SRCS of the first logic state supplied from the timing controller 200 Turn on to supply the sensor reset voltage SRV to the plurality of data lines DL1 to DLm by electrically shorting the plurality of data lines DL1 to DLm. Here, the sensor reset voltage SRV is a voltage for resetting the sensor capacitor C of the sensor unit 120 (see FIG. 2) formed in each pixel P, and is the same as the drive voltage VDD or the common voltage Vcom But may have an arbitrary voltage level supplied from the outside or the gamma voltage generating section 413. In this case,

Each of the plurality of switching elements SW is turned off according to the sensor reset control signal SRCS of the second logic state supplied from the timing controller 200 so that the analog pixel voltages PV1 to PVm To be supplied to the plurality of data lines DL1 to DLm.

2, the sensing signal receiving unit 500 receives a sensing signal from the sensor unit 120 of each pixel P according to a display gate signal supplied to the display gate line DGL of the liquid crystal display panel 100, (SSL), and supplies the sensing signal SS to the timing controller 200.

On the other hand, the sensing signal receiving unit 500 receives a sensing signal SS output to each of the sensing signal output lines SSL from the sensor unit 120 of each pixel P every frame, and transmits the sensing signal SS to the timing control unit 200 However, in order to improve the sensitivity characteristic of the sensor unit 120, the sensing signal SS received at least every two frames may be transmitted to the timing controller 200.

The backlight unit 600 irradiates light generated by at least one light source (for example, a lamp or a light emitting diode) disposed on the back surface or the side surface of the liquid crystal display panel 100 to the back surface of the liquid crystal display panel 100 do. At this time, the backlight unit 600 adjusts the luminance of the light radiated to the liquid crystal display panel 100 so as to correspond to the dimming signal DIM supplied from the timing controller 200.

8 is a driving waveform diagram for schematically explaining a driving method of a liquid crystal display according to an embodiment of the present invention.

Referring to FIG. 8, a driving method of a liquid crystal display according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG.

First, in the display period DP of the N frame, the display gate signal is supplied to the first display gate line DGL1 and the pixel voltage PV is supplied to each of the data lines DL1 to DLm, P display unit 110 displays an image corresponding to the pixel voltage PV in response to the display gate signal. At the same time, the sensing signal receiving unit 500 detects the sensing signal output from the sensor unit 120 of each pixel P in response to the display gate signal supplied to the first display gate line DGL1, , And supplies the received sensing signal to the timing controller 200 at least every one frame. Accordingly, the timing controller 200 supplies the sensing signal supplied from the sensing signal receiver 500 to the external system body.

Subsequently, as described above, the display gate signals are sequentially supplied to the second to the n-th display gate lines DGLn during the N-frame, and the pixel voltage PV corresponding to each of the data lines DL1 to DLm is supplied Thereby displaying an image corresponding to N frames on the liquid crystal display panel 100. [ At the same time, the sensing signal receiving unit 500 receives a sensing signal detected by the sensor unit 120 of each pixel P and output to the sensing signal output line SSL according to the driving of each display gate line DGL And supplies the received sensing signal to the timing control unit 200 at least every one frame.

Subsequently, in the blanking interval BP between the N frame and the N + 1 frame, the sensor gate signal is supplied to the sensor gate line SGL and the sensor reset voltage SRV is applied to each data line DL1 to DLm. The sensor thin film transistor ST and the sensor capacitor C of the sensor unit 120 provided in each pixel P are reset by using the sensor reset voltage SRV. The reset of the sensor unit 120 is preferably performed in the blanking interval BP of at least one frame unit.

Subsequently, in the display period DP of the (N + 1) -th frame, each pixel P is driven in the same manner as the display period DP of the N frames described above. In the blanking period BP, Lt; / RTI >

The liquid crystal display according to the embodiment of the present invention displays a predetermined image using the display unit 110 formed on each pixel P and uses the sensor unit 120 formed on each pixel P An incident light ray according to a user's operation is detected and outputted to the outside so that a user interface function as well as an image display function can be performed.

In addition, the present invention can reduce the power consumption by adjusting the brightness of the backlight unit 600 according to the ambient illuminance of the liquid crystal display panel 100 detected by the sensor unit 120.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. It will be understood by those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. .

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view for explaining a pixel structure of a general liquid crystal display device. FIG.

2 is a schematic view for explaining a liquid crystal display according to an embodiment of the present invention.

FIG. 3 schematically illustrates a pixel structure according to an embodiment of the present invention shown in FIG. 2. Referring to FIG.

4 is a graph for schematically explaining characteristics according to an incident light ray of the sensor thin film transistor shown in FIG.

FIG. 5 is a diagram for schematically explaining the data driver shown in FIG. 2. Referring to FIG.

6 is a schematic view for explaining the first embodiment of the voltage output unit shown in FIG.

7 is a schematic diagram for explaining a second embodiment of the voltage output unit shown in FIG.

8 is a driving waveform diagram for schematically explaining a driving method of a liquid crystal display according to an embodiment of the present invention.

Description of the Related Art [0002]

100: liquid crystal display panel 110:

120: sensor unit 200: timing control unit

300: Gate driver 400: Data driver

Claims (9)

A liquid crystal display device comprising a liquid crystal display panel for displaying an image using light transmittance of each of a plurality of pixels arranged in a matrix form, Wherein each of the plurality of pixels comprises: A display unit for displaying the image by adjusting a light transmittance according to a pixel voltage supplied to the data line and a common voltage supplied to the common electrode in response to a display gate signal supplied to the display gate line; And And outputs a sensing signal corresponding to the generated photocurrent in response to the display gate signal supplied to the display gate line and outputs a sensing signal corresponding to the sensor gate And a sensor unit reset by a sensor reset voltage supplied to the data line according to a signal. The method according to claim 1, Wherein the incident light is one of a laser, an infrared ray, a visible ray, and an ultraviolet ray. The method according to claim 1, The sensor unit includes: A sensor thin film transistor connected to the sensor gate line and the data line for outputting a photocurrent corresponding to the incident light; A sensor capacitor formed between the sensor thin film transistor and the common electrode and storing a photo voltage corresponding to the photoelectric current; A first thin film transistor which is connected to the display gate line and the driving power supply line and outputs a driving voltage supplied from the driving power supply line in accordance with the display gate signal; And And a second thin film transistor connected to the first thin film transistor and the sensing signal output line and adapted to switch the sensing signal corresponding to the light voltage by switching the light voltage stored in the sensor capacitor and the first thin film transistor, And a second thin film transistor for outputting the signal to a signal output line. The method of claim 3, Wherein the sensor thin film transistor and the sensor capacitor are reset by the sensor reset voltage supplied to be synchronized with the gate signal for the sensor. The method of claim 3, And the driving voltage is the common voltage. The method according to claim 1, A data driver for supplying the pixel voltage to the data line or supplying the pixel reset voltage; A gate driver for supplying a display gate signal to the display gate line or supplying a sensor gate signal to the sensor gate line; A sensing signal receiver for receiving the sensing signal output to the sensing signal output line; And And a timing controller for controlling the driving timing of each of the data driver and the gate driver and for transmitting the sensing signal supplied from the sensing signal receiver to the outside. The method according to claim 6, The timing control unit generates a sensor reset control signal for supplying the sensor gate signal and the sensor reset voltage during a blanking interval between a frame and a frame in units of at least one frame to control the gate driving unit and the data driving unit . 8. The method of claim 7, The data driver may include: A pixel voltage generator for generating the pixel voltage corresponding to the data signal supplied from the timing controller according to the control of the timing controller; And And a voltage output unit for selectively supplying the pixel voltage and the pixel voltage to the data line according to the sensor reset control signal supplied from the timing control unit. The method according to claim 6, Further comprising a backlight unit for emitting light to the liquid crystal display panel, The timing control unit detects the ambient illuminance of the liquid crystal display panel according to natural or artificial light incident on the liquid crystal display panel using the sensing signal supplied from the sensing signal receiver, Of the liquid crystal display panel.

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