KR20070002327A - Liquid crystal display and method for driving the same - Google Patents

Abstract

An LCD and a driving method thereof are provided to realize a color scanning mode together with a display mode, a black and white scanning mode, and a touch sensing mode, and prevent color mixing and color interference by separating white light emitted from a backlight unit into red light, green light, and blue light in the color scanning mode. An LCD panel includes an array substrate and a color filter substrate facing each other, and a liquid crystal layer filled between the color filter substrate and the array substrate. In the LCD panel, a plurality of sub pixels are alternately formed on the array substrate, and a display mode in which an image is displayed according to a gate signal and a gradation voltage, and a scanning mode in which a scanning signal is outputted by detecting incident light are selectively driven. A driving circuit unit includes a gate driver(210) sequentially supplying the gate signal to the sub pixels, a source driver(220) applying the display gradation voltage or a scanning gradation voltage to the sub pixel to control alignment for each location of the liquid crystal layer, a read-out circuit(230) reading the scanning signal, and a mode control circuit(251) controlling timings of the gate driver, the source driver, and the read-out circuit for operation in the display mode and the scanning mode. A backlight unit emits white light to the LCD panel. The scanning mode is one of a black and white scanning mode, a touch sensing mode, and a color scanning mode. In the color scanning mode, the scanning gradation voltage is applied to have a different value for each sub pixel to separate white light emitted from the backlight unit into single-colored light of red, green and blue.

Description

Liquid crystal display and method for driving the same {Liquid crystal display and method for driving the same}

1 is a configuration diagram showing a conventional liquid crystal display device.

2 is a block diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a configuration diagram illustrating the driving circuit unit of FIG. 2.

4 is a configuration diagram illustrating the liquid crystal display panel of FIG. 2.

FIG. 5 is a plan view schematically illustrating a subpixel configured in the array substrate of FIG. 4.

6 is an equivalent circuit diagram of FIG. 5.

7 is a flowchart illustrating a method of driving a liquid crystal display according to an exemplary embodiment of the present invention.

8 to 10 are diagrams for describing some of the steps of FIG. 7.

(Explanation of symbols for the main parts of the drawing)

100: liquid crystal display panel 110: array substrate

120: color filter substrate 130: liquid crystal layer

200: driving circuit portion 210: gate driver

220: source driver 230: lead out circuit

240: analog board 250: digital board

300: host computer 400: backlight unit

The present invention relates to a liquid crystal display device and a driving method thereof, and more particularly, to a liquid crystal display device and a driving method thereof capable of scanning.

A liquid crystal display device injects a liquid crystal material having anisotropic dielectric constant between a color filter substrate on which a common electrode, a color filter, a black matrix, and the like are formed, and an array substrate on which a switching element, a pixel electrode, and the like are formed, and common with the pixel electrode. A display device that expresses a desired image by adjusting the intensity of an electric field formed in a liquid crystal material by applying different potentials to electrodes, thereby changing the molecular arrangement of the liquid crystal material, and controlling the amount of light transmitted through the transparent insulating substrate. . As the liquid crystal display, a thin film transistor liquid crystal display (TFT LCD) using a thin film transistor (TFT) as a switching element is mainly used.

1 is a configuration diagram showing a conventional liquid crystal display device.

A conventional liquid crystal display device is composed of a liquid crystal display panel 10 for displaying an image and a driving circuit portion 20 for driving the liquid crystal display panel 10, as shown in FIG. By applying a voltage to the pixel electrode to control the liquid crystal, the light emitted from the backlight unit passes or is blocked, and the image is displayed by passing through the color filters of red (R), green (G), and blue (B). Done.

Gate lines and data lines cross each other in the liquid crystal display panel 10, and thin film transistors and pixel electrodes are disposed at each intersection to form a plurality of sub-pixels. The image is displayed according to the gate signal supplied through the line and the display gray voltage supplied through the data line.

The driving circuit unit 20 may include a source driver 24 for driving data lines of the liquid crystal display panel 10 and a gate driver 25 for driving gate lines of the liquid crystal display panel 10. ), A timing controller 22 for controlling the driving timing of the source driver 24 and the gate driver 25, a gamma voltage generator 23 for supplying a gamma voltage to the source driver 24, and a power supply for And a power supply unit 26. The driving circuit unit 20 receives pixel data from the video card 30 through the interface 21 and displays an image according to the resolution of the liquid crystal display panel 10.

The gamma voltage generator 23 generates a gamma voltage by a resistor group in which a plurality of resistors are arranged in series, and the source driver 24 uses the gamma voltages supplied from the gamma voltage generator 23 to interface 21. The pixel data supplied from the video card 30 is converted into the display gray voltage through the display. Here, the pixel data is generally a digital signal having a value between 0 and 255.

Since the liquid crystal display is a light-receiving display device that does not emit light by itself, a backlight unit (BLU) is installed on the back of the liquid crystal display panel that displays an image and maintains the brightness of the entire screen uniformly. Depending on the structure of the array substrate, it can be divided into the type used for display and the type used for sensor (fingerprint sensor, X-ray image detection sensor, etc.).

In order to use the backlight unit as a scanning light source, a liquid crystal display used for a sensor is generally applied to a gray level voltage of a white level to each sub pixel of an array substrate to drive the entire liquid crystal material to achieve a maximum transmission state. When the entire liquid crystal material is in the maximum transmissive state, light emitted from the backlight unit passes through the front surface of the color filter substrate, and thus the light emitted through the liquid crystal display panel 10 and used as the scanning light source becomes white light.

However, when white light is used during the scanning operation, the black and white scanning that senses only contrast does not cause a problem. On the other hand, when scanning the color, color mixing or color interference occurs, which greatly reduces the quality of the color scan image. There was a problem.

Accordingly, the technical problem to be achieved by the present invention is to implement a color scanning mode together with a display mode, a black and white scanning mode, and a touch sensing mode, and converts the white light emitted from the backlight unit into the three colors of red, green, and blue in the color scanning mode. Another object of the present invention is to provide a liquid crystal display device capable of separating and improving mixed color and color interference.

Another object of the present invention is to provide an efficient driving method of the liquid crystal display device described above.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

According to another aspect of the present invention, there is provided a liquid crystal display device including an array substrate facing each other, a color filter substrate, and a liquid crystal layer filled between the color filter substrate and the array substrate. A plurality of subpixels are alternately formed on a substrate, and a liquid crystal display panel in which a display mode for displaying an image according to a gate signal and a display gray voltage and a scanning mode for sensing incident light and outputting a scanning signal are selectively driven. And a gate driver for sequentially supplying the gate signal to the subpixel, a source driver for adjusting the positional alignment of the liquid crystal layer by applying the display gray voltage or the scanning gray voltage to the subpixel, and reading the scanning signal. The shipment out lead circuit, the display mode and the A driving circuit unit including a mode control circuit for controlling timing of the gate driver, the source driver, and the readout circuit so as to be driven in a scanning mode, and a backlight unit for irradiating white light to the liquid crystal display panel; The mode may be at least one of a monochrome scanning mode, a touch sensing mode, and a color scanning mode, and in the color scanning mode, the scanning gray voltage is applied to have a different value in units of the sub-pixels to red-white the white light emitted from the backlight unit. It is characterized by separating into monochromatic light of green and blue.

The array substrate may be formed on the first transparent insulating substrate, the gate line and the data line intersecting each other on the first transparent insulating substrate to define the sub-pixel, and the intersection of the gate line and the data line, and the display gray voltage. Or a display thin film transistor to which the scanning gray voltage is applied, a lead out line facing the data line, a sensor thin film transistor to output a current of incident light, a storage capacitor to store a current output from the sensor thin film transistor, and the storage It is preferable to include a switching thin film transistor for transferring a current stored in a capacitor to the read out circuit through the read out line.

The color filter substrate may include red, green, and blue color filters that are alternately formed on a second transparent insulating substrate and the second transparent insulating substrate to face the sub-pixels, respectively.

In the color scanning mode, the scanning gray voltage applied in units of the sub-pixels may be a gray voltage of a white level or a gray voltage of a black level.

The driving circuit unit is coupled to an output terminal of the read-out circuit, the differential amplifier unit amplifies the offset signal of the two inputs by inputting the scanning signal and the reference voltage output from the read-out circuit, the digital amplified offset signal It is preferable to further include an analog-to-digital converter for converting the signal to the mode control circuit, and a frame memory in which the transmitted scanning signal is stored in units of frames.

The readout circuit may include a sampling unit for sampling the scanning signal according to a data clock, an amplifier for amplifying the sampled scanning signal, and sequentially shifting the amplified scanning signal according to the data clock and outputting the data in units of data lines. It is preferable to include a shift register portion.

In addition, the driving method of the liquid crystal display according to an embodiment of the present invention for achieving the above technical problem is that the mode control circuit is set to the display mode or scanning any one of the monochrome scanning mode, touch sensing mode, color scanning mode Setting a mode, and when the display mode is set, displaying the image on the liquid crystal panel by applying a gate signal and a display gray voltage to each subpixel of the liquid crystal panel; When the mode is set to the scanning mode, the mode control circuit is applied to the gray level voltage of the white level to all the sub-pixels of the liquid crystal display panel to read the scanning signal for each frame contrast, and if the touch sensing mode, The mode control circuit is applied to all subpixels of the liquid crystal display panel. Reading position information in units of frames by applying a gray level voltage of a light level, and when the mode scanning circuit is set to the color scanning mode, a scanning gray voltage having different values in subpixel units in the liquid crystal display panel; It is characterized in that it comprises the step of reading the scanning signal for each color by applying.

When the color scanning mode is set, the step of the mode control circuit reading the scanning signal for each color by applying a scanning gray voltage having different values in units of subpixels to the liquid crystal display panel may include red color of the liquid crystal display panel. Reading a red scanning signal by applying a gray level voltage of a white level to a subpixel facing the color filter, and applying a gray level voltage of a black level to a subpixel facing the green and blue color filters; Reading a green scanning signal by applying a gray level voltage of a white level to a sub-pixel opposite to and applying a gray level voltage of a black level to a sub-pixel opposite to the red and blue color filters; The gray level voltage of the white level is applied to the opposing sub-pixels, and the red and green color filters Applying a gradation voltage of the black level pixels in the probe reading to a blue scanning signal may include the steps:

When the color scanning mode is set, the step of the mode control circuit reading the scanning signal for each color by applying a scanning gray voltage having different values in units of subpixels to the liquid crystal display panel may include red color of the liquid crystal display panel. Reading a red scanning signal by applying a gray level voltage of a white level to a subpixel facing the color filter and applying a gray level voltage of a black level to a subpixel facing the green and blue color filters; Applying a gray level voltage of a black level to all subpixels of the pixel, applying a gray level voltage of a white level to a subpixel facing the green color filter, and applying a black level to a subpixel facing the red and blue color filters Reading a green scanning signal by applying a gray voltage of the subpixel; Applying a gray level voltage of a black level to the sub pixel facing the blue color filter, and applying a gray level voltage of a black level to the sub pixels facing the red and green color filters. The method may include reading a blue scanning signal and applying a black level gray voltage to all subpixels of the liquid crystal display panel.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Like reference numerals refer to like elements throughout.

Hereinafter, a liquid crystal display and a driving method thereof according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is a block diagram showing a driving circuit unit of FIG. 2.

Referring to FIG. 2, the liquid crystal display according to the exemplary embodiment includes a liquid crystal display panel 100, a driving circuit unit 200 driving the liquid crystal display panel 100, and the like.

A plurality of sub pixels are formed in the liquid crystal display panel 100, and a display mode for displaying an image according to a gate signal and a display gray voltage and a scanning mode for sensing incident light and outputting a scanning signal are selectively driven.

The scanning mode is classified into a black and white scanning mode, a touch sensing mode, and a color scanning mode. In the color scanning mode, the scanning gray voltage applied to the liquid crystal display panel 100 has different values in units of subpixels, so that the liquid crystal from the backlight unit is reduced. White light emitted from the display panel 100 is separated into monochromatic light of red, green, and blue. In this way, by separating the white light into red, green, and blue monochromatic light, the interference between colors is reduced to increase the color purity.

The driving circuit unit 200 includes a source driver 220, a gate driver 210, a readout circuit 230, an analog board 240, and a digital board 250, and the analog board 240 includes an analog-to-digital converter ( 241, a differential amplifier 242, and the like are mounted, and the digital board 250 is equipped with a mode control circuit 251, a USB controller 253, and the like.

In more detail, as shown in FIG. 3, the driving circuit 200 includes the gate driver 210, the source driver 220, the readout circuit 230, the differential amplifier 242, and the analog-to-digital converter 241. And a mode control circuit 251, a video card 252, a USB controller 253, a frame memory 254, and the like.

The gate driver 210 sequentially supplies a gate signal to each subpixel of the liquid crystal display panel 100.

The source driver 220 applies a display gray voltage or a scanning gray voltage to the subpixels of the liquid crystal display panel 100 to adjust the position-specific orientation of the liquid crystal layer filled in the liquid crystal display panel 100.

The readout circuit 230 reads a scanning signal from the liquid crystal display panel 100 in the scanning mode. The readout circuit 230 may include a sampling unit for sampling a scanning signal according to a data clock, an amplifier for amplifying the sampled scanning signal, and a shift register unit for sequentially shifting the amplified scanning signal according to a clock and outputting the data in units of data lines. It is preferable to include.

The readout circuit 230 amplifies the charged and stored charges in each sub-pixel of the liquid crystal display panel 100 in the form of an analog voltage having a constant amplification ratio, and outputs it in the form of voltage through a sampling and analog holding process.

The mode control circuit 251 controls timings of the gate driver 210, the source driver 220, and the readout circuit 230 to be driven in the display mode and the scanning mode, respectively, and uses a general purpose such as a field programmable gate array (FPGA). It can be implemented using logic.

The gate driver 210 and the source driver 220 are controlled to be driven in both the display mode and the scanning mode, and the readout circuit 230 is controlled to be driven only in the scanning mode. That is, in the display mode, the mode control circuit 251 operates the gate driver 210 and the source driver 220 to receive the pixel data and the clock corresponding to the resolution of the liquid crystal display panel 100 from the video card 252 and display the display. In the scanning mode, the readout circuit 230 is also controlled to perform the scanning operation.

The differential amplifier 242 is coupled to the output terminal of the readout circuit 230 and amplifies the offset signals of the two inputs using the scanning signal and the reference voltage output from the readout circuit 230 as inputs. The analog-to-digital converter 241 converts the amplified offset signal into a digital signal and transmits it to the mode control circuit 251. The frame memory 254 stores the transmitted scanning signal in units of frames.

That is, the analog voltage output from the readout circuit 230 is converted into digital data through the analog-to-digital converter 241, and the converted digital data is stored in the frame memory 254 before being called by the host computer 300. Accordingly, it is transmitted through USB communication using the USB controller 253 and displayed on the host computer 300 in an environment in which the window application program is executed.

At the same time, the digital data stored in the frame memory 254 is displayed on the liquid crystal display panel 100 by data and clock processing of the mode control circuit 251, thereby scanning the target object F with one liquid crystal display panel 100. FIG. Scanning and displaying the scanned image together.

4 is a configuration diagram illustrating the liquid crystal display panel of FIG. 2.

Referring to FIG. 4, the liquid crystal display panel 100 includes an image of an array substrate 110 and a color filter substrate 120, a liquid crystal layer 130, a color filter substrate 120, and an array substrate 110 facing each other. The backlight unit 400 includes first and second polarizing plates 112 and 122 disposed at a lower side thereof, and includes a backlight unit 400 for irradiating white light to the rear surface.

The array substrate 110 includes a first transparent insulating substrate 111 and a plurality of sub pixels formed on the first transparent insulating substrate 111. Each sub-pixel is formed to face the red, green, and blue color filters R, G, and B that are alternately formed on the color filter substrate 120, and the scan object F is performed when performing a scanning operation in the scanning mode. Sensor thin film transistor 114 for sensing the light reflected by the.

The color filter substrate 120 is alternately formed on the second transparent insulation substrate 121 facing the first transparent insulation substrate 111, the black matrix BM blocking the light leakage, and the second transparent insulation substrate 121. And red, green, and blue color filters R, G, and B that face each sub-pixel of the array substrate 110.

The liquid crystal layer 130 is filled between the color filter substrate 120 and the array substrate 110.

When the liquid crystal display is driven in the color scanning mode, the white light emitted from the backlight unit 400 is separated into red, green, and blue monochromatic light by applying different gray voltages to each sub-pixel of the array substrate 110. In addition, color scanning without color interference is implemented.

For convenience of explanation, hereinafter, subpixels facing the red, green, and blue color filters R, G, and B will be referred to as red, green, and blue subpixels, respectively. In addition, the gray level voltage of the white level is applied to the sub pixel so that the liquid crystal layer 130 above the sub pixel becomes the maximum transmissive state, and the gray level voltage of the black level is applied to the sub pixel. The liquid crystal layer 130 above the subpixel is defined as an off state of the subpixel.

In the related art, all the sub-pixels of the array substrate 110 are turned on to make the entire liquid crystal layer 130 in the maximum transmissive state, whereby white light emitted from the backlight unit 400 is used as a scanning light source. There is a problem in that color purity decreases due to interference between colors.

For example, when the document to be scanned (F) is red, when the light transmitted through the red sub-pixel is reflected in the document, the light incident on the sensor thin film transistor 114 of the red sub-pixel not only the red sub-pixel Green and blue sub-pixels were affected, resulting in a failure to scan a correct color image. When the interference between the sensor thin film transistors 114 occurs, even when the color scanning mode is implemented, color is difficult to be expressed (divided), and the position resolution capability is deteriorated.

According to the present invention, the red, green, and blue subpixels may be independently driven in the color scanning mode, thereby eliminating color interference and improving color purity.

FIG. 5 is a plan view schematically illustrating a subpixel configured in the array substrate of FIG. 4.

Referring to FIG. 5, each subpixel of the array substrate 110 includes a display thin film transistor 113, a sensor thin film transistor 114, a storage capacitor 115, and a switching thin film transistor 116.

The display thin film transistor 113 receives a display gray voltage or a scanning gray voltage through a data line and changes the molecular arrangement of the liquid crystal layer 130 according to the voltage level of the applied gray voltage. 120) to adjust the amount of light transmitted.

The sensor thin film transistor 114 outputs a current of light that is reflected by the scan object F and is incident.

The storage capacitor 115 stores the current output from the sensor thin film transistor 114.

The switching thin film transistor 116 transfers the current stored in the storage capacitor 115 to the readout circuit 230 through a readout line.

In the display mode, an image is displayed on the color filter substrate 120 according to the display gray voltage applied to the display thin film transistor 113, and in the scanning mode, the sensor thin film transistor ( 114, scanning is performed while the storage capacitor 115 and the switching thin film transistor 116 operate. The scan object F may be scanned through the liquid crystal display and then displayed on the color filter substrate 120 again.

More specifically, in the scanning mode, the display thin film transistor 113 controls the transmission state of the liquid crystal layer 130 in subpixel units by the gray scale voltage, and the sensor thin film transistor 114 of the color filter substrate 120 The current is supplied to the storage capacitor 115 according to the amount of light of the monochromatic light reflected from the scan object F placed thereon.

In the color scanning mode, the red, green, and blue subpixels are alternately turned on, and are independently driven so that when the one subpixel is turned on, the other two subpixels are turned off.

6 is an equivalent circuit diagram of FIG. 5.

Referring to FIG. 6, a gate line and a data line are alternately arranged in each subpixel, and a read-out line is disposed to face the data line. The reset line and the storage line are disposed to face the gate line.

In the initial state, the bias voltage Vbias is applied to the source electrode of the sensor thin film transistor 114 through a reset line, and the storage line is applied to the gate electrode of the sensor thin film transistor 114 and the switching thin film transistor 116. The common voltage Vcom is applied through the storage line.

The drain electrode of the sensor thin film transistor 114 and the source electrode of the switching thin film transistor 116 are electrically connected. The storage capacitor 115 is positioned between the drain electrode and the gate electrode of the sensor thin film transistor 114.

When the scan object F is placed on the color filter substrate 120, the light incident from the backlight unit 400 is reflected by the scan object F to the sensor thin film transistor 114. In this case, the light reflected by the switching thin film transistor 116 is blocked by a light shield on the switching thin film transistor 116.

Light incident on the sensor thin film transistor 114 activates the active layer, and the degree of activation of the active layer is determined by the amount of incident light.

In the scanning mode, a constant gate-source voltage is applied to the source electrode and the gate electrode of the sensor thin film transistor 114, but since the active layer is activated as light enters the sensor thin film transistor 114, the source electrode and the drain electrode More current flows than when the scan object F is not recognized.

The current flowing through the source electrode and the drain electrode of the sensor thin film transistor 114 is temporarily stored by the storage capacitor 115 and then transmitted to the switching thin film transistor 116. The data voltage transferred from the storage capacitor 115 to the switching thin film transistor 116 is applied to the source electrode of the switching thin film transistor 116.

The switching thin film transistor 116 is turned on by a turn-on voltage serving as a gate signal applied to the gate electrode and a data voltage applied to the source electrode. When the switching thin film transistor 116 is turned on, an output voltage serving as a scanning signal is applied to the drain electrode of the switching thin film transistor 116. The output voltage applied to the drain electrode is transferred to the readout circuit 230 through the readout line.

In the color scanning mode, the readout circuit 230 receives the current stored in the storage capacitor 115 through the switching thin film transistor 116 to read the color-specific scanning signals for the red, green, and blue monochromatic light, respectively. The scanned signals for each color are combined and stored as color images in frame units.

7 is a flowchart illustrating a method of driving a liquid crystal display according to an exemplary embodiment of the present invention.

First, in step S100, the mode control circuit 251 is set to the display mode or to any one of the black and white scanning mode, the touch sensing mode, and the color scanning mode.

Next, when the display mode is set, in step S110, the mode control circuit 251 displays an image on the liquid crystal display panel 100 by applying a gate signal and a display gray voltage to each subpixel of the liquid crystal display panel 100. do.

Next, when the black and white scanning mode is set, in step S120 and S130, the mode control circuit 251 applies the gray level voltage of the white level to all the subpixels of the liquid crystal display panel 100 so that the contrast-specific scanning signal for each frame unit is performed. Read out.

Next, when the touch sensing mode is set, in step S140 and S150, the mode control circuit 251 reads the position information in units of frames by applying the gray level voltage of the white level to all the subpixels of the liquid crystal display panel.

Next, when the color scanning mode is set, in step S160 and S170, the mode control circuit 251 applies the scanning gray voltage having different values in subpixel units to the liquid crystal display panel 100 to scan the color-specific scanning signal. Read out.

In operation S140, a driving order of each subpixel is arbitrarily determined, and each subpixel may be driven by the following two methods.

First, the process of driving the red, green, and blue subpixels alternately on is repeated.

Second, while driving the red, green, and blue subpixels in an on state alternately, a gray level voltage of a black level is applied to all the subpixels while the subpixels driving in the on state are changed. This method is intended to reduce interference in the sensitivity of the sensor thin film transistor 114 to each of the red, green and blue subpixels.

In the first method, applying a white level gray voltage to the red subpixel of the liquid crystal display panel 100 and applying a black level gray voltage to the green and blue subpixels to read a red scanning signal; Reading a green scanning signal by applying a gray level voltage of a white level to the green subpixel, applying a gray level voltage of a black level to the red and blue subpixels, and applying a white level gray level voltage to the blue subpixel, The step of reading a blue scanning signal by applying a black level gray voltage to the red and green subpixels is repeated a predetermined number of times.

In the second method, applying a white level gray voltage to the red subpixel of the liquid crystal display panel 100 and applying a black level gray voltage to the green and blue subpixels to read a red scanning signal; A black level gray voltage is applied to all the subpixels of the liquid crystal display panel 100, a white level gray voltage is applied to the green subpixel, and a black level gray voltage is applied to the red and blue subpixels. Reading a scanning signal, applying a gray level voltage of a black level to all subpixels of the liquid crystal display panel 100, applying a gray level voltage of a white level to a blue subpixel, and applying a red level to the red and green subpixels. Reading a blue scanning signal by applying a gray level gray voltage, and applying a gray level gray voltage to all subpixels of the liquid crystal display panel 100. A is repeated a predetermined number of times.

8 to 10 are diagrams for explaining some of the steps of FIG. 7, and show that the white light emitted from the backlight unit 400 is separated into monochromatic light of red, green, and blue in step S160.

In FIG. 8, the gray level voltage of the maximum transmissive state is applied and turned on only to the red subpixel, and the gray level voltage of the minimum state is applied to the green and blue subpixels to be turned off.

In this manner, when sensing the red portion of the document to be the scan object F, light is transmitted only to the red subpixels, and the green and blue subpixels are turned off so that only the sensor thin film transistor 114 of the red subpixel is turned off. By accepting light, color purity is improved.

In FIG. 9, the gray scale voltage of the maximum transmissive state is turned on only in the green subpixel, and the gray scale voltage of the minimum state is applied to the red and blue subpixels, thereby being turned off.

In FIG. 10, the grayscale voltage of the maximum transmissive state is applied and turned on only to the blue subpixel, and the grayscale voltage of the minimum state is applied to the red and green subpixels to be turned off.

In the color scanning mode, the sensor thin film transistor 114 disposed in each sub pixel is always driven in an off state, so that the current flow varies greatly according to the amount of light separated into monochromatic light, and the switching thin film transistor of each sub pixel ( 116 alternately reads the red, green, and blue scanning signals for colors of red, green, and blue while repeating turn-on and turn-off, and transmits them to the readout circuit 230.

That is, the sensor thin film transistor 114 that functions as an image sensor is embedded in each sub-pixel, and the light emitted from the liquid crystal display panel is used as the scanning light source during the scanning operation, and the backlight unit 400 is used to implement color scanning. Scanning the color image of the scan object (F) while driving the white light emitted by the red, green, blue monochromatic light separately.

For example, when a twist nematic liquid crystal operating in a normally white mode is filled in the liquid crystal layer 130, the transmittance increases as the voltage applied to the voltage-transmittance characteristic of the twist nematic liquid crystal increases. Will be lowered. Therefore, in order to separate the red light by turning on only the red subpixel as shown in FIG. 8, a low voltage of the white level, which is the gradation voltage of the highest transmissive state, is applied to the red subpixel, and the minimum transmissive state is applied to the green and blue subpixels. The high voltage of the black level which becomes a gradation voltage is applied.

In this manner, the color image of the scan object F is scanned while driving the red, green, and blue subpixels separately.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, since the embodiments described above are provided to fully inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

The liquid crystal display according to the exemplary embodiment of the present invention configured as described above may implement a color scanning mode together with a display mode, a black and white scanning mode, and a touch sensing mode, and red, white, white light emitted from the backlight unit in the color scanning mode. By separating into three colors of green and blue, mixed color and color interference can be improved.

In addition, the driving method of the liquid crystal display according to the exemplary embodiment of the present invention can efficiently drive such a liquid crystal display.

Claims (8)

An array substrate facing each other, a color filter substrate, a liquid crystal layer filled between the color filter substrate, and the array substrate are provided, and a plurality of subpixels are alternately formed on the array substrate, and the gate signal and the display gray voltage A liquid crystal display panel configured to selectively drive a display mode for displaying an image and a scanning mode for detecting incident light and outputting a scanning signal; A gate driver for sequentially supplying the gate signal to the subpixel, a source driver for adjusting the positional alignment of the liquid crystal layer by applying the display gray voltage or the scanning gray voltage to the subpixel, and reading the scanning signal A driving circuit unit including a mode control circuit for controlling timing of the gate driver, the source driver, and the readout circuit so as to be driven in a readout circuit, the display mode, and the scanning mode; A backlight unit radiating white light to the liquid crystal display panel; The scanning mode may be at least one of a monochrome scanning mode, a touch sensing mode, and a color scanning mode, and in the color scanning mode, the white light emitted from the backlight unit is applied so that the scanning gray voltage has a different value in units of the subpixels. The liquid crystal display device which isolate | separates into monochromatic light of red, green, and blue. The method of claim 1, The array substrate, A gate line and a data line intersecting each other on the first transparent insulating substrate and the first transparent insulating substrate to define the sub-pixel, and formed at an intersection of the gate line and the data line, and the display gray voltage or the scanning gray scale. A display thin film transistor to which a voltage is applied, a lead out line facing the data line, a sensor thin film transistor outputting a current of incident light, a storage capacitor storing a current output from the sensor thin film transistor, a current stored in the storage capacitor It includes a switching thin film transistor for transmitting to the lead out circuit through the lead out line, The color filter substrate, And a red, green, and blue color filter formed alternately on a second transparent insulating substrate and on the second transparent insulating substrate to face the sub-pixels, respectively. The method of claim 1, In the color scanning mode, The scanning gray voltage applied in the sub-pixel units is a gray voltage of a white level or a gray voltage of a black level. The method of claim 1, The driving circuit unit, A differential amplifier coupled to an output terminal of the readout circuit and amplifying offset signals of two inputs by inputting the scanning signal and the reference voltage output from the readout circuit, converting the amplified offset signal into a digital signal, and And an analog-to-digital converter for transmitting to a mode control circuit, and a frame memory for storing the transmitted scanning signal in units of frames. The method of claim 1, The lead out circuit is, A sampling unit for sampling the scanning signal according to a data clock, an amplifier for amplifying the sampled scanning signal, and a shift register unit for sequentially shifting the amplified scanning signal according to the data clock and outputting the data in units of data lines; A liquid crystal display device, characterized in that. Setting the mode control circuit to a display mode or to any one of a monochrome scanning mode, a touch sensing mode, and a color scanning mode; When the display mode is set to the display mode, displaying the image on the liquid crystal display panel by applying a gate signal and a display gray voltage to each subpixel of the liquid crystal display panel; When the black and white scanning mode is set, the mode control circuit reading the contrast-specific scanning signal in units of frames by applying a gray level voltage of a white level to all subpixels of the liquid crystal display panel; Reading, by the mode control circuit, position information in units of frames by applying a gray level voltage of a white level to all subpixels of the liquid crystal display panel when the touch sensing mode is set to the touch sensing mode; And When the color scanning mode is set, the mode control circuit reads out a scanning signal for each color by applying scanning gray voltages having different values to the liquid crystal display panel in subpixel units; Method of driving the display device. The method of claim 6, When the color scanning mode is set, the mode control circuit reading the color-specific scanning signal by applying scanning gray voltages having different values in units of subpixels to the liquid crystal display panel may include: Reading a red scanning signal by applying a gray level voltage of a white level to a subpixel facing the red color filter of the liquid crystal display panel, and applying a gray level voltage of a black level to a subpixel facing the green and blue color filters. ; Reading a green scanning signal by applying a gray level voltage of a white level to a sub pixel facing the green color filter, and applying a gray level voltage of a black level to a sub pixel facing the red and blue color filters; And The method of reading a blue scanning signal by applying a gray level voltage of a white level to a sub pixel facing the blue color filter and applying a gray level voltage of a black level to a sub pixel facing the red color filter. The method of driving a liquid crystal display device characterized by repeating as much as it is. The method of claim 6, When the color scanning mode is set, the mode control circuit reading the color-specific scanning signal by applying scanning gray voltages having different values in units of subpixels to the liquid crystal display panel may include: Reading a red scanning signal by applying a gray level voltage of a white level to a subpixel facing the red color filter of the liquid crystal display panel, and applying a gray level voltage of a black level to a subpixel facing the green and blue color filters. ; Applying a gray level gray voltage to all subpixels of the liquid crystal display panel; Reading a green scanning signal by applying a gray level voltage of a white level to a sub pixel facing the green color filter, and applying a gray level voltage of a black level to a sub pixel facing the red and blue color filters; Applying a gray level gray voltage to all subpixels of the liquid crystal display panel; Reading a blue scanning signal by applying a gray level voltage of a white level to a sub pixel facing the blue color filter and applying a gray level voltage of a black level to a sub pixel facing the red and green color filters; And And applying the gray level voltage of a black level to all the sub-pixels of the liquid crystal display panel a predetermined number of times.

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