KR102405183B1 - Display device having touch sensor and driving method thereof - Google Patents

Abstract

The present invention relates to a display device having a touch sensor and a method of driving the same, and generates a power-off signal when input power is lowered to a preset reference value or less, and in response to the power-off signal, connects sensor lines between a common voltage source and a base voltage source. connect to any one

Description

A display device having a touch sensor and a driving method thereof

The present invention relates to a display device in which sensor lines are discharged when power is abnormally turned off, and a driving method thereof.

A user interface (UI) enables communication between a person (user) and various electrical and electronic devices, so that the user can easily control the device as he or she wants. Representative examples of the user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technology is developing in the direction of increasing user sensitivity and ease of operation. Recently, a user interface has been developed into a touch UI, a voice recognition UI, a 3D UI, and the like.

The touch UI detects a touch input by implementing a touch screen on the display panel and transmits the user input to the electronic device. Touch UI is essential for portable information devices such as smart phones, and is being applied to notebook computers, computer monitors, and home appliances.

A technology for realizing a touch screen using a technology for embedding touch sensors in a pixel array of a display panel is being applied to various display devices. The touch sensors may be implemented as a capacitive type touch sensor that senses a touch based on a change in capacitance before and after the touch.

Since the touch sensors are embedded in the pixel array of the display panel, the touch sensors are coupled to the pixels through parasitic capacitance. In order to reduce the mutual influence due to the coupling of pixels and touch sensors, the in-cell touch sensor technology divides one frame period into a display period and a touch sensing period to time-division the driving time of pixels and the driving time of the touch sensors.

The driver of the display device includes a data driver supplying the data voltage of the input image to data lines of the display panel to the pixels during the display period, and a gate driver supplying a gate pulse (or scan pulse) synchronized with the data voltage during the display period ( or a scan driver), and a touch sensor driver that drives the touch sensors during the touch sensing period.

The power of the system including the display device may be turned off abnormally. For example, when a sudden power outage occurs or a battery is replaced in a mobile terminal such as a smart phone, the power of the display device is turned off without a preset power off sequence. In order to prevent an afterimage of the display device when power is abnormally turned off, a method for discharging pixels and signal wires of the display device has been proposed. However, since there is no method for rapidly discharging the sensor lines connected to the pixels when the power of the display device is abnormally turned off, an afterimage or stain may be seen on the screen due to residual charges charged in the sensor lines.

The present invention provides a display device having a touch sensor capable of rapidly discharging a touch sensor and sensor lines connected to the touch sensor when power is abnormally turned off, and a method of driving the same.

A display device according to an embodiment of the present invention includes: a display panel including data lines, gate lines, and sensor lines connected to pixels, the sensor lines connected to a touch sensor; a touch sensor driver supplying a common voltage to the sensor lines during a display period and supplying a touch sensor driving signal to the sensor lines during a touch sensing period; a power-off signal generator for generating a power-off signal when the input power is lowered below a preset reference value; and a controller for connecting the sensor lines to any one of a common voltage source and a base voltage source in response to the power-off signal.

When the power-off signal is generated, the sensor lines are discharged.

The controller controls the multiplexer of the touch sensor driver in response to the power-off signal to connect the sensor lines to the common voltage source.

The controller generates a touch enable signal defining the display period and the touch sensing period as different logical values. The controller controls the logic value of the touch enable signal to be a logic value defining the display period in response to the power-off signal.

The touch sensor driver connects the sensor lines to the common voltage source in response to the touch enable signal when the power-off signal is generated.

The control unit includes a switch element for connecting the sensor lines to the base voltage source in response to the power-off signal.

In the display device, a data signal of an input image is supplied to the data lines during the display period, and a no-load signal generated in the same phase with respect to the touch sensor driving signal during the touch sensing period is supplied to the data lines. ; and a gate driver supplying a gate pulse synchronized with a data signal of an input image to the gate lines during the display period and supplying the no-load signal to the gate lines during the touch sensing period.

The data driver discharges the data lines in response to the power-off signal. The gate driver discharges the gate lines in response to the power-off signal.

The method of driving the display device includes supplying a common voltage to the sensor lines during a display period, supplying a touch sensor driving signal to the sensor lines during a touch sensing period, and when input power is lowered to a preset reference value or less. generating a power-off signal, and discharging the sensor lines by connecting the sensor lines to any one of a common voltage source and a base voltage source in response to the power-off signal.

The present invention controls the touch sensor driver when the input power is abnormally cut off to connect the sensor lines to a common voltage source or a base voltage source to discharge the sensor lines. As a result, the display device of the present invention can prevent an afterimage or stain due to residual charges of the sensor lines when the input power is abnormally cut off.

1 is a diagram schematically showing a display device according to an embodiment of the present invention.
2 is a diagram illustrating an example in which a screen of a display device is divided and driven into a plurality of blocks.
FIG. 3 is a block diagram showing the configuration of a drive integrated circuit (IC) shown in FIG. 1 .
4 is a view showing a sensor driver, a sensor line, and a touch sensor electrode.
5 is a diagram illustrating in detail a multiplexer for driving a touch sensor.
6 is a waveform diagram showing a touch sensor control signal and a signal applied to the touch sensor electrodes.
7 and 8 are waveform diagrams illustrating a method of driving pixels and touch sensors.
9 is a waveform diagram showing a power-off signal.
10 is a diagram illustrating an example in which a power-off signal is generated at a high voltage of a touch sensor driving signal.
11 is a diagram illustrating a method of discharging sensor lines by controlling a multiplexer for driving a touch sensor when a power-off signal is generated.
12 is a waveform diagram illustrating a method of discharging sensor lines using a touch enable signal when a power-off signal is generated.
13 is a diagram illustrating a method of discharging sensor lines when a power-off signal is generated by connecting a separate switch element to the sensor lines.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. The present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains It is provided to fully understand the scope of the invention, and the present invention is only defined by the scope of the claims.

The shape, size, ratio, angle, number, etc. disclosed in the drawings for explaining the embodiment of the present invention are exemplary, and therefore the present invention is not limited to the matters shown in the drawings. Like reference numerals refer to substantially identical elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

When "includes", "includes", "having", "consisting of", etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, it may be interpreted as the plural unless otherwise explicitly stated.

In interpreting the components, it is construed as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship between two components is described as 'on One or more other elements may be interposed between those elements in which 'directly' or 'directly' are not used.

1st, 2nd, etc. may be used to distinguish the components, but the functions or structures of these components are not limited to the ordinal number or component name attached to the front of the component.

The following embodiments can be partially or wholly combined or combined with each other, and technically various interlocking and driving are possible. Each of the embodiments may be implemented independently of each other or may be implemented together in a related relationship.

The display device of the present invention may be implemented as a flat panel display device such as a liquid crystal display (LCD) or an organic light emitting diode display (OLED display). In the following embodiments, a liquid crystal display will be mainly described as an example of a flat panel display, but the present invention is not limited thereto. For example, the present invention can be applied to any display device including a touch sensor.

The touch sensors may be disposed on the screen of the display panel as an on-cell type or an add-on type, or an in-cell type touch sensor may be built into the display panel. Although the in-cell touch sensor will be mainly described in the following embodiments, the touch sensor of the present invention is not limited thereto.

The controller of the present invention discharges all wires connected to the pixels when the input power is abnormally cut off to prevent afterimages or stains on the screen. The control unit may be disposed in a drive IC described in the following embodiments. For example, the controller may be implemented as a timing signal generator and a touch sensor driver to discharge sensor lines connected to the touch sensors.

1 is a diagram schematically showing a display device according to an embodiment of the present invention. 2 is a diagram illustrating an example in which a screen of a display device is divided and driven into a plurality of blocks. FIG. 3 is a block diagram showing the configuration of a drive integrated circuit (IC) shown in FIG. 1 . 4 is a view showing a sensor driver, a sensor line, and a touch sensor electrode.

1 to 4 , the display device of the present invention includes a display panel PNL and a drive IC DIC for driving the display panel PNL.

A screen of the display panel PNL is a matrix defined by data lines 11 , gate lines 12 orthogonal to the data lines 11 , and data lines 11 and gate lines 12 . and a pixel array AA in which pixels are arranged in a shape. The screen of the display panel PNL further includes touch sensors and sensor lines connected to the touch sensors. A polarizing film is adhered to each of the upper and lower plates of the display panel PNL. A backlight unit (BLU) may be disposed under the display panel PNL.

The pixel array AA of the display panel PNL may be divided into a TFT array and a color filter array. A TFT array may be formed on an upper plate or a lower plate of the display panel PNL. The TFT array includes TFTs (Thin Film Transistor, T) formed at intersections of the data lines 11 and the gate lines 12, the pixel electrode of the liquid crystal cell Clc charging the voltage of the data signal, the common voltage ( Vcom) is supplied to the common electrode of the liquid crystal cell Clc and a storage capacitor (Cst) connected to the pixel electrode to maintain a data voltage, and the like, to display an input image. The storage capacitor is omitted from the drawing. The TFT array further includes sensor lines 10 and electrodes 21 to 24 of touch sensors connected to the sensor lines 10 .

A color filter array may be formed on an upper or lower plate of the display panel PNL. The color filter array includes a black matrix, a color filter, and the like. In the case of a COT (Color Filter on TFT) ? or TOC (TFT on Color Filter) ? model, a color filter and a black matrix together with a TFT array may be disposed on one substrate.

A gate driver GIP may be formed in the display panel PNL. The gate driver GIP includes a shift register that outputs a gate pulse synchronized with a data signal in response to a gate timing control signal input through the drive IC DIC. The gate timing control signal includes a start pulse and a shift clock. The shift register sequentially supplies the gate pulses to the gate lines 12 by shifting the gate pulses according to the shift clock timing. In FIG. 7 , “CLK” denotes a shift clock generated during the display periods D1 and D2.

Since the shift clock CLK is generated only in the display periods D1 and D2, the gate driver GIP shifts the gate pulse during the display periods D1 and D2 and stops the shift operation during the touch sensing period S1. The TFTs T of the display panel PNL are turned on according to a gate pulse to select a line of the display panel PNL in which data of an input image is written. The shift register may be directly formed on the substrate of the display panel PNL in the same process as the TFT array of the pixel array.

The touch sensor may be implemented as a capacitive type touch sensor, for example, a mutual capacitance sensor or a self capacitance sensor. Self-capacitance is formed along a single layer of conductor wiring formed in one direction. Mutual capacitance is formed between two orthogonal conductor wirings. 3 illustrates a self-capacitance type touch sensor, the touch sensors of the present invention are not limited thereto.

The pixels of the pixel array AA may include red (R), green (G), and blue (B) sub-pixels for color implementation. Each of the pixels may further include a white (W) sub-pixel in addition to the RGB sub-pixels. Each of the sub-pixels includes a TFT (T), a pixel electrode and a common electrode of the liquid crystal cell (Clc), and a storage capacitor (Cst). The TFT (T) is turned on according to the gate high voltage (VGH) of the gate pulse to supply the data voltage on the data line 11 to the pixel electrode of the liquid crystal cell Clc. The liquid crystal molecules of the liquid crystal cell Clc are driven according to a voltage difference between the data voltage applied to the pixel electrode and the common voltage Vcom applied to the common electrode to delay the phase of light incident on the display panel PNL.

The touch sensors may be formed on the display panel PNL and electrically connected to the pixels. Each of the electrode patterns of the touch sensors may be formed as a divided pattern of a common electrode connected to a plurality of pixels. As shown in FIG. 4 , the touch sensor may be connected to a plurality of pixels to supply a common voltage Vcom to the plurality of pixels during a display period, and may sense a touch input during a touch sensing period.

One frame period of the display panel PNL is time-divided into one or more display periods and one or more touch sensing periods in order to drive the touch sensors and pixels embedded in the pixel array AA. As shown in FIG. 2 , the pixel array AA of the display panel PNL is time-division driven in two or more blocks B1 to BM. The blocks B1 to BM do not need to be physically divided in the display panel PNL. The pixel array AA of the display panel PNL is dividedly driven into display sections separated by a touch sensing section in which the touch sensors are driven therebetween.

The blocks B1 to BM are time-division driven with a touch sensing section interposed therebetween. For example, during the first display period, after the pixels of the first block B1 are driven and current frame data is written to the pixels, a touch input is sensed over the entire screen during the first touch sensing period. Following the first touch sensing period, the pixels of the second block B2 are driven during the second display period, and current frame data is written to the pixels. Subsequently, the touch input is sensed over the entire screen during the second touch sensing period. Here, the touch input includes a direct touch input of a finger or a stylus pen, a proximity touch input, a fingerprint touch input, and the like.

This method of driving the touch sensor may make a touch report rate faster than a frame rate of the screen. The frame rate is the frequency at which frame data is updated on the screen. In the NTSC (National Television Standards Committee) scheme, the frame rate is 60 Hz. In the PAL (Phase-Alternating Line) scheme, the frame rate is 50 Hz. A touch report rate is a frequency at which touch input coordinates are generated. According to the present invention, the touch report rate can be increased more than twice as fast as the frame rate of the screen by dividing the screen into preset blocks and generating coordinates by driving the touch sensor between display sections to increase the touch sensitivity.

The drive IC (DIC) supplies the data signal of the input image to the data lines 11 during the display period, and drives the touch sensors during the touch sensing period to sense the touch input. The drive IC (DIC) includes a power supply unit 130 , a timing signal generation unit 100 , a data driving unit 110 , a touch sensor driving unit 120 , and a power off signal (abnormal power off, hereinafter referred to as “APO signal”) generating unit. (90) is provided.

The power supply unit 130 generates DC power required for driving the display panel PNL by using a DC-DC converter. The DC-DC converter includes a charge pump, a regulator, a buck converter, a boost converter, and the like. The power supply unit 130 receives power required to drive the pixels and touch sensors of the display panel PNL, for example, a DC input power such as AVDD, AVEE, or VDDI from an external power source. AVDD and AVEE may be generated with voltages of +5.5V and -5.5V, respectively, in the mobile device, but are not limited thereto. The power supply unit 130 generates a liquid crystal driving voltage, an on/off voltage (VGH, VGL) of the TFT(T), a gamma compensation voltage, and a voltage of a touch driving signal by using a regulator and a charge pump. VDDI is a driving voltage of a logic circuit unit of the drive IC and may be generated as a voltage controlling the drive IC (DIC), for example, 1.8V.

The APO signal generator 90 monitors a DC input power source Vin such as AVDD, AVEE, or VDDI, and generates an APO signal when the DC input power source Vin is abnormally low. In the case of a mobile device, an APO signal may be generated when the battery is suddenly disconnected.

The data driver 110 discharges the data lines 11 in response to the APO signal, and the gate driver GIP discharges the gate lines 12 in response to the APO signal. The power supply unit 130 discharges the output terminals when the APO signal is generated. When the DC input power supply (Vin) of AVDD, AVEE, VDDI, etc. is abnormally low, the common voltage (Vcom) and the on/off voltages (VGH, VGL) of the TFT(T) change to the base voltage (GND-0V) and the pixel their voltage is discharged. The touch sensor driver 120 discharges the sensor lines 10 when the APO signal is generated. Accordingly, when it is determined that the DC input power Vin is abnormally cut off, the display device of the present invention discharges all wires connected to the pixels to prevent afterimages and stains.

The timing signal generator 100 transmits pixel data of an input image received from a host system (not shown) to the data driver 110 . The timing signal generator 100 receives a timing signal received in synchronization with pixel data to receive a data timing control signal for controlling the operation timing of the data driver 110 and for controlling the operation timing of the gate driver GIP Generates a gate timing control signal. A demultiplexer (MUX) may be disposed between the drive IC (DIC) and the data lines 11 . In this case, the timing signal generator 100 generates a MUX control signal for controlling a demultiplexer (MUX).

In addition, the timing signal generator 100 generates the touch sensor control signal shown in FIG. 6 . The touch sensor control signal includes the touch enable signal TEN, the MUX control signals TMUX1 to TMUX3 for controlling the multiplexer for driving the touch sensor (hereinafter referred to as “AMUX”) 121 , and the control of the sensing unit 122 . Generates signals and clocks. The first logical value of the touch enable signal TEN defines the touch sensing period S1 , and the second logical value of the touch enable signal TEN defines the display periods D1 and D2 . In the example of FIG. 6 , the first logic value may be a high level, and the second logic value may be a low level, but is not limited thereto.

The host system may be any one of a television system, a set-top box, a navigation system, a personal computer (PC), a home theater system, a mobile device system, and a wearable system. The host system converts the digital video data of the input image into a format suitable for display on the display panel (PNL). The host system transmits the timing signal together with the digital video data of the input image to the timing signal generator 100 . The display device illustrated in FIG. 1 is an example of a display device applied to a mobile device.

The data driver 110 receives the pixel data (digital data) of the input image from the timing signal generator 100 during the display period, latches it, and then performs a digital-to-analog converter (hereinafter referred to as "DAC"). ) is supplied. The DAC converts the pixel data into a gamma compensation voltage to generate a voltage of the data signal.

The voltage of the data signal output from the data driver 110 is supplied to the data lines 11 . The multiplexer MUX distributes the data voltage input from the data driver 110 to the data lines 11 under the control of the timing signal generator 100 . In the case of the 1:3 multiplexer, the multiplexer time-divisions the data voltage input through one output channel of the data driver 110 and distributes it to three data lines. If a 1:3 multiplexer is used, the number of channels of the data driver 110 can be reduced by 1/3.

The data driver 110 supplies a no-load signal of the same phase as the touch sensor driving signal to the data lines 11 during the touch sensing period, and connects the data lines 11 to a common voltage source or a base voltage source in response to the APO signal. Thus, the data lines 11 may be discharged.

The data driver 110 supplies a no-load signal of the same phase as the touch sensor driving signal to the data lines 11 during the touch sensing period, and connects the data lines 11 to a common voltage source or a base voltage source in response to the APO signal. Thus, the data lines 11 may be discharged. The gate driver GIP supplies the no-load signal of the same phase as the touch sensor driving signal to the gate lines 12 during the touch sensing period, and connects the gate lines 12 to the base voltage source in response to the APO signal to connect the gate line It is possible to discharge the fields (12).

The touch sensor driver 120 supplies the common voltage Vcom, which is the reference potential of the pixels, to the sensor lines 10 during the display period. The touch sensor driver 120 drives the touch sensors by supplying a touch sensor driving signal to the sensor lines 10 to supply electric charges to the touch sensor electrodes 21 to 24 during the touch sensing period. The touch sensor driver 120 determines a touch input by measuring a change in capacitance before and after a touch input in each of the touch sensors during the touch sensing period, outputs touch data Txy indicating the coordinates of the touch input location, and transmits it to the host system.

As shown in FIG. 4 , the touch sensor driving unit 120 includes an AMUX 121 , a sensing unit 122 , and an algorithm execution unit 123 . The AMUX 121 selects the sensor lines 10 connected to the sensing unit 122 under the control of the algorithm execution unit 123 . The AMUX 121 may reduce the number of channels of the sensing unit 122 by sequentially connecting the sensor lines 10 to the channels of the sensing unit 122 in response to the MUX control signals TMUX1 to TMUX3 during the touch sensing period. have.

The AMUX 121 supplies the common voltage Vcom to the sensor lines 10 during the display periods D1 and D2. In addition, the AMUX 121 supplies a touch sensor driving signal to the sensor lines 10 during the touch sensing period S1, and when the touch sensor driving signal is not applied during the touch sensing period S1, the base voltage GND or , a common voltage Vcom is supplied to the sensor lines 10 or the sensor lines are controlled to a high impedance HiZ state.

The sensing unit 122 supplies a touch sensor driving signal to the touch sensors through the AMUX 121 and the sensor lines 10 to charge the touch sensors, and the sensor line 10 connected through the AMUX 121 . ), amplifies and integrates the amount of charge received from the touch sensors, and converts it into digital data to sense the change in capacitance before and after touch input. To this end, the sensing unit 122 includes an amplifier for amplifying the touch sensor signal received from the sensor line 10 , an integrator for accumulating the output voltage of the amplifier, and an analog-to-digital converter for converting the voltage of the integrator into digital data. -Digital Converter, hereinafter referred to as "ADC") and the like. The digital data output from the ADC is transmitted to the algorithm execution unit 123 as touch raw data indicating a change in capacitance of the touch sensor before and after a touch input.

The algorithm execution unit 123 compares the touch data received from the touch sensor driver 120 with a preset threshold, detects touch data higher than the threshold, and generates coordinates of each touch input. The algorithm execution unit 123 transmits the coordinates Txy of each touch input to a host system (not shown).

5 is a diagram showing the AMUX 121 in detail. 6 is a waveform diagram showing a touch sensor control signal and a signal applied to the touch sensor electrodes.

5 and 6 , the AMUX 121 includes a multiplexer 1222 and a demultiplexer 1211 .

The multiplexer 1222 includes a first input terminal IN1 selected during the display period, a second input terminal IN1 during a touch sensing period, a control terminal to which the MUX control signal TMUX is input, and an input terminal of the demultiplexer 1211 . Includes connected output terminals.

As described above, the first logical value of the touch enable signal TEN defines the touch sensing period S1 , and the second logical value of the touch enable signal TEN defines the display periods D1 and D2 . do. The MUX control signal TMUX may be generated as a second logic value during the display periods D1 and D2 and may be generated as a first logic value during the touch sensing period S1. The MUX control signal TMUX is shifted as shown in FIG. 6 so that the touch sensor electrodes 21 to 24 are sequentially connected to the sensing circuit 122 . For example, after the AMUX 121 supplies a touch sensor driving signal to the first touch sensor electrode 21 through the first sensor line 10 in response to the first MUX control signal TMUX1 during the touch sensing period, , supplying a touch sensor driving signal to the second touch sensor electrode 22 through the second sensor line 10 in response to the second MUX control signal TMUX2, and then in response to the third MUX control signal TMUX3 A touch sensor driving signal is supplied to the third touch sensor electrode 23 through the third sensor line 10 .

The multiplexer 1222 connects the first input terminal IN1 to the input terminal of the demultiplexer 1211 in response to the second logic value of the MUX control signal TMUX. The common voltage Vcom is supplied to the first input terminal IN1 of the multiplexer 1222 . Accordingly, during the display periods D1 and D2 , the common voltage Vcom selected by the multiplexer 1222 is supplied to the input terminal of the demultiplexer 1211 .

The switch element SW is connected to the second input terminal IN2 of the multiplexer 1222 . The switch element SW transmits a load free driving signal (LFD) to the second input terminal IN2 of the multiplexer 1222 as shown in FIG. 6 in response to the first logic value of the MUX control signal TMUX. supply to A load free driving signal (LFD) is a touch sensor driving signal supplied to the sensor lines 10 when the MUX control signal TMUX is generated as a first logic value during the touch sensing period S1 . The no-load signal LFD minimizes parasitic capacitance between the touch sensors and pixels during the touch sensing period S1 to increase the signal to noise ratio (hereinafter referred to as “SNR”) of the touch sensors. can be improved In order to reduce the parasitic capacitance of the touch sensor electrodes 21 to 24 and the sensor lines 10 , the no-load signal LFD synchronized with the no-load signal LFD applied to the sensor lines 10 is applied to the data line 11 . ) and the gate line 12 may also be applied. The no-load signal LFD applied to the data lines 11 and the gate lines 12 is generated with the same phase and the same voltage with respect to the no-load signal LFD applied to the sensor lines 10 .

The switch element SW supplies any one of the ground voltage GND and the common voltage Vcom to the second input terminal IN2 of the multiplexer 1222 in response to the second logic value of the MUX control signal TMUX, or It may be turned off and controlled to a high impedance (HiZ) state. The high impedance (HiZ) state refers to a floating state in which the switch element is turned off and no voltage is applied to the second input terminal of the multiplexer 1222 . Accordingly, when the MUX control signal TMUX is the first logic value during the touch sensing period S1 , the touch sensor driving signal selected by the multiplexer 1222 , that is, the no-load signal LFD is supplied to the input terminal of the demultiplexer 1211 . . Then, during the touch sensing period S1 , the ground voltage GND or the common voltage Vcom selected by the multiplexer 1222 is supplied to the input terminal of the demultiplexer 1211 or the input terminal of the demultiplexer 1211 has a high impedance HiZ ) can be in the state.

The demultiplexer 1211 includes an input terminal connected to an output terminal of the multiplexer 1222, a plurality of output terminals CH1, CH1, and CH2 respectively connected to the plurality of sensor lines 10, and the MUX control signal TMUX. Includes control terminals.

The demultiplexer 1211 simultaneously supplies the common voltage Vcom supplied through the multiplexer 1222 to the sensor lines 10 during the display periods D1 and D2 .

The demultiplexer 1211 connects the input terminal to the first output terminal CH1 in response to the first logic value of the first MUX control signal TMUX1 as shown in FIG. 6 during the touch sensing period S1, The input terminal is connected to the second output terminal CH2 in response to the first logic value of the second MUX control signal TMUX2, and then the input terminal is connected to the input terminal in response to the first logic value of the third MUX control signal TMUX3 It is connected to the third output terminal (CH3). The demultiplexer 1211 supplies the ground voltage GND or the common voltage Vcom to the sensor lines 10 when the MUX control signals TMUX1 , TMUX2 , and TMUX3 have the second logic value during the touch sensing period S1 , or The lines 10 are controlled to a high impedance (HiZ) state.

7 and 8 are waveform diagrams illustrating a method of driving pixels and touch sensors.

7 and 8 , one frame period may be time-divided into display periods D1 and D2 and touch sensing periods S1 and S2. When the display frame rate is 60 Hz, one frame period is approximately 16.7 ms. One touch sensing period S1 and S2 is allocated between the display periods D1 and D2. In FIG. 6 , the first touch sensing period S1 is an example in which 6.7 ms is allocated.

The data driver 110 and the gate driver GIP of the drive IC DIC write the current frame data to the pixels of the first block B1 during the first display period D1 and reproduce the data in the first block B1. The image being used is updated with the current frame data. During the first display period D1, pixels of the remaining block B2 except for the first block B1 maintain previous frame data. The touch sensor driver 120 supplies the common voltage Vcom to the touch sensors during the first display period D1.

The touch sensor driver 120 sequentially drives all touch sensors in the screen during the first touch sensing period S1 to sense a touch input. The touch sensor driver 120 analyzes touch data obtained from the touch sensors during the second touch sensing period S2 to generate touch report data including coordinate information and identification information (ID) of each touch input. and send it to the host system.

The data driver 110 and the gate driver GIP write the current frame data to the pixels of the second block B2 during the second display period D2 to display the image reproduced in the second block B2 as current frame data. update to During the second display period D2, pixels of the remaining block B1 except for the second block B2 maintain previous frame data. The touch sensor driver 120 supplies a common voltage Vcom, which is a common voltage of pixels, to the touch sensors during the second display period D2.

The touch sensor driver 120 sequentially drives all touch sensors in the screen during the second touch sensing period S2 to sense a touch input. The touch sensor driver 120 analyzes touch data obtained from the touch sensors during the second touch sensing period S2, generates touch report data including coordinate information and identification information (ID) of each touch input, and transmits it to the host system do.

A voltage Vtouch of the no-load signal LFD applied to the sensor lines 10 is equal to the driving voltage of the touch sensors. In FIG. 8 , ΔVtouch = ΔVd = ΔVg. ΔVd is the voltage of the no-load signal LFD applied to the data lines 11 , and ΔVg is the voltage of the no-load signal LFD applied to the gate lines 11 . Accordingly, in each of the parasitic capacitance between the data line 11 and the touch sensor during the touch sensing period S1 and S2 , the parasitic capacitance between the gate line 12 and the touch sensor, and the parasitic capacitance between the sensor lines 10 , the parasitic Since there is no voltage difference between the two ends of the capacitance, the parasitic capacitance is minimized.

9 is a waveform diagram showing an APO signal.

Referring to FIG. 9 , when power is abnormally cut off, the host system may invert the reset signal ARST to low logic. When the power is abnormally cut off, the DC input power Vin supplied to the display device is discharged. The APO signal generator 90 monitors the DC input power Vin by comparing the DC input power Vin with a reference value Vth preset in a register.

The APO signal generator 90 generates the APO signal as a high logic voltage when the DC input power Vin is lower than the reference value Vth when the reset signal ARST has a low logic voltage. The display device of the present invention discharges the wirings 10, 11, and 12 connected to the pixels when the APO signal is generated as high logic. 7 is an example in which the wires 10 , 11 , and 12 connected to the pixels are discharged to a base voltage (GND=0V) when the APO signal is generated in the second touch sensing period S2 .

When the APO signal is generated, if the touch sensor driving signal Vtouch is a low voltage Vl, the sensor lines 10 are rapidly discharged, but when the touch sensor driving signal Vtouch is a high voltage Vh, the sensor lines 10 ) takes a long time to discharge, so an afterimage or stain may appear on the screen. The display device of the present invention rapidly discharges the sensor lines 10 regardless of the voltage of the touch sensor driving signal Vtouch by using the method shown in FIGS. 11 to 13 .

11 is a diagram illustrating a method of discharging the sensor lines 10 by controlling the AMUX 121 when an APO signal is generated.

Referring to FIG. 11 , the APO signal generator 90 generates an APO signal when power is abnormally cut off. In this case, the timing signal generator 100 controls the AMUX 121 in response to the APO signal to connect an input terminal to which the common voltage Vcom is supplied to the sensor lines 10 . For example, the timing signal generator 100 connects the common voltage source to the sensor lines 10 through the AMUX 121 using the MUX control signal TMUX. The common voltage source may be the first input terminal IN1 or the second input terminal IN2 of the AMUX 121 to which the common voltage Vcom is input as shown in FIG. 5 . Since the output terminals of the power supply unit 130 are discharged when the power is abnormally cut off, the common voltage Vcom is discharged to 0V. Accordingly, when the sensor lines 10 are connected to the common voltage source through the AMUX 121 when the APO signal is generated, the sensor lines 10 may be rapidly discharged to 0V. In FIG. 11 , “M1” is a switch element of the demultiplexer ( FIG. 1 , MUX) connected to the data line 11 , and “M2” is a switch element connected to a common voltage source in the AMUX 121 . In FIG. 11 , “G1 to Gn” are numbers of the gate lines 12 .

12 is a waveform diagram illustrating a method of discharging sensor lines using a touch enable signal TEN when an APO signal is generated.

Referring to FIG. 12 , the timing signal generator 100 generates the touch enable signal TEN as a first logic value during the touch sensing periods S1 and S2 in a normal state in which the APO signal is not generated, and the display period During (D1, D2), the touch enable signal TEN is inverted by the second logic. When the touch enable signal TEN is the first logic in a normal state, the touch sensor driver 120 sequentially supplies the no-load signal LFD to the sensor lines 10 to sense the touch input, and the touch enable signal A common voltage Vcom is supplied to the sensor lines 10 when (TEN) is the second logic.

When the APO signal is generated when the power is abnormally cut off, the timing signal generator 100 inverts the touch enable signal TEN to the second logic in response to the APO signal. At this time, the AMUX 121 of the touch sensor driver 120 supplies the common voltage Vcom to the sensor lines 10 in response to the second logic of the touch enable signal TEN. Since the output terminals of the power supply unit 130 are discharged when the power is abnormally cut off, the common voltage Vcom is discharged to 0V. Accordingly, when the touch enable signal TEN is generated as the second logic when the APO signal is generated, the sensor lines 10 may be rapidly discharged to 0V.

13 is a diagram illustrating a method of discharging the sensor lines when an APO signal is generated by connecting a separate switch element M3 to the sensor lines 10 .

Referring to FIG. 13 , the display device of the present invention further includes a switch element M3 connected to the sensor lines 10 and turned on in response to an APO signal APO_Vcom.

The switch element M3 connects the sensor lines 10 to the ground voltage source (GND=0V) in response to the APO signal APO_Vcom generated when power is abnormally cut off. A level shifter (not shown) converts the voltage level of the APO signal generated from the APO signal generator 90 into on/off voltages VGH and VGL of the transistor. The APO signal APO_Vcom output from the level shifter is supplied to the gate of the switch element M3. Accordingly, when the APO signal is generated, the sensor lines 10 may be rapidly discharged to 0V.

The switch element M3 may be implemented as a transistor including a gate to which the APO signal APO_Vcom is applied, a drain connected to the sensor line 10 , and a source connected to the ground voltage source GND.

Those skilled in the art from the above description will be able to see that various changes and modifications are possible without departing from the technical spirit of the present invention. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

DIC : Drive IC PNL : Display panel
TEN: Touch enable signal TMUX, TMUX1~TMUX3: MUX control signal
10: sensor line 11: data line
12: gate line 21 to 24: touch sensor electrode
90: APO signal generating unit 100: timing signal generating unit
110: data driving unit 120: touch sensor driving unit
130: power unit 121: multiplexer for driving a touch sensor (AMUX)

Claims (10)

a display panel including data lines, gate lines, and sensor lines connected to pixels, the sensor lines connected to a touch sensor;
a touch sensor driver supplying a common voltage to the sensor lines during a display period and supplying a touch sensor driving signal to the sensor lines during a touch sensing period;
a power-off signal generator for generating a power-off signal when the input power is lower than a preset reference value;
a power supply unit for discharging output terminals in response to the power-off signal; and
and a controller connecting the sensor lines to a common voltage source discharged as the output terminals are discharged in response to the power-off signal. The method of claim 1,
A display device having a touch sensor in which the sensor lines are discharged when the power-off signal is generated. The method of claim 1,
the control unit
A display device having a touch sensor configured to connect the sensor lines to the common voltage source by controlling a multiplexer of the touch sensor driver in response to the power-off signal. The method of claim 1,
the control unit
generating a touch enable signal defining the display section and the touch sensing section as different logical values;
A display device having a touch sensor configured to control a logic value of the touch enable signal to a logic value defining the display section in response to the power-off signal. 5. The method of claim 4,
The touch sensor driving unit,
A display device having a touch sensor that connects the sensor lines to the common voltage source in response to the touch enable signal when the power-off signal is generated. delete The method of claim 1,
a data driver supplying a data signal of an input image to the data lines during the display period and supplying a no-load signal generated in the same phase with the touch sensor driving signal to the data lines during the touch sensing period; and
a gate driver that supplies a gate pulse synchronized with the data signal of the input image to the gate lines during the display period and supplies the no-load signal to the gate lines during the touch sensing period;
The data driver discharges the data lines in response to the power-off signal, and the gate driver discharges the gate lines in response to the power-off signal. A method of driving a display device comprising: a display panel comprising data lines, gate lines and sensor lines connected to pixels, the sensor lines connected to a touch sensor, the method comprising:
supplying a common voltage to the sensor lines during a display period and supplying a touch sensor driving signal to the sensor lines during a touch sensing period;
generating a power-off signal when the input power falls below a preset reference value;
discharging output terminals of the power supply unit in response to the power-off signal; and
and discharging the sensor lines by connecting the sensor lines to a common voltage source discharged as the output terminals are discharged in response to the power-off signal. 9. The method of claim 8,
A method of driving a display device having a touch sensor in which the sensor lines are discharged when the power-off signal is generated. 9. The method of claim 8,
supplying a data signal of an input image to the data lines during the display period;
supplying a no-load signal generated in the same phase to the touch sensor driving signal to data lines during the touch sensing period;
supplying a gate pulse synchronized with a data signal of an input image to the gate lines during the display period;
supplying the no-load signal to gate lines during the touch sensing period;
discharging the data lines in response to the power-off signal; and
and discharging the gate lines in response to the power-off signal.

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