KR101719418B1 - Touch sensor integrated type display device and driving method of the same - Google Patents

Abstract

The present invention relates to an organic light emitting diode (OLED) display device, and more particularly, to an OLED display device for improving touch performance when a touch sensor is driven, To the power supply terminals of the pixels as well as to the data lines and scan lines connected to the in-cell touch sensors, thereby minimizing the influence of parasitic capacitance on the in-cell touch sensors.

Description

TECHNICAL FIELD [0001] The present invention relates to a touch sensor integrated type display device and a driving method thereof.

The present invention relates to a display device in which touch sensors are embedded in a pixel array.

A user interface (UI) enables a user (a user) to communicate with various electric or electronic devices, allowing the user to easily control the device as desired. Representative examples of the user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), a remote controller having infrared communication or radio frequency (RF) communication functions. User interface technology has been developed to enhance the user's sensibility and ease of operation. Recently, the user interface has evolved into a touch UI, a voice recognition UI, a 3D UI, and the like.

Touch UI is essential for portable information devices such as smart phones, and is being applied to notebook computers, computer monitors, and home appliances. 2. Description of the Related Art In recent years, a technology for incorporating touch sensors in a pixel array of a display panel (hereinafter referred to as "In-cell touch sensor") has been proposed. Incelel touch sensor technology can install touch sensors on the display panel without increasing the thickness of the display panel. These touch sensors are connected to the pixels through parasitic capacitance. In order to reduce the mutual influence due to coupling of the pixels and the touch sensors, one frame period includes a period for driving pixels (hereinafter referred to as a "display driving period") and a period for driving touch sensors Quot; touch sensor driving period Tt ").

The Insel touch sensor technology utilizes the electrodes connected to the pixels of the display panel as the electrodes of the touch sensors. For example, there is a method of dividing a common electrode for supplying a common voltage to pixels of a liquid crystal display device and utilizing the divided common electrode patterns as electrodes of touch sensors, for example.

Such an insensitive touch sensor technology is difficult to apply to organic light emitting display devices. The reason for this is that it is not easy to pattern the electrode for utilizing the internal electrode as the touch sensor in the organic light emitting display device and the pixel structure of the organic light emitting display device is more complicated than that of the liquid crystal display device, The parasitic capacitance is relatively large due to the coupling between them. As the parasitic capacitance increases, the touch sensitivity and the accuracy of the touch recognition deteriorate.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a touch sensor integrated type display device and a driving method thereof, which can improve touch performance when an inelens touch sensor technology is implemented using an organic light emitting display device.

According to an aspect of the present invention, there is provided a touch sensor integrated type display device including a display panel, a touch sensor driving unit, a data driving unit, a gate driving unit, and a power supply unit. The display panel includes pixels including the OLED and touch sensors, and is time-division driven by a display driving period for image display and a touch sensor driving period (Tt) for touch sensing. The touch sensor driving unit supplies a touch driving signal to the touch sensors during the touch sensor driving period to sense a capacitance change of the touch sensors. The data driver supplies a data voltage of the input image to the data lines of the display panel during the display driving period and supplies an AC signal having the same phase as the touch driving signal to the data lines during the touch sensor driving period. The gate driver supplies a scan pulse synchronized with the data voltage to the scan lines of the display panel during the display driving period and supplies the AC signal to the scan lines during the touch sensor driving period. The power supply unit supplies DC power to the power terminal of the pixels during the display driving period and supplies the AC signal to the power terminal during the touch sensor driving period.

The OLED of the pixels maintains a turn-off state during the touch sensor driving period.

The gate driver simultaneously applies an emission pulse of an off level to the emission lines during the touch sensor driving period to block the driving current applied to the OLED of the pixels.

The touch sensors are implemented as cathode electrodes of the OLED patterned in a predetermined unit, and the touch sensor driver supplies the low potential power source voltage of the DC power source type to the touch sensors during the display driving period.

The power supply terminal may include a first terminal connected to the OLED during the display driving period and to which a high potential power supply voltage is applied and a second terminal to which a reference voltage for initializing the OLED is applied during the display driving period, The AC signal is supplied to the first terminal and the second terminal during the touch sensor driving period.

The touch sensor driving period includes a vertical blanking period in which the data voltage of the input image is not written to the display panel.

The AC signal has the same amplitude as the touch driving signal.

A method of driving a touch sensor integrated type display device according to the present invention includes pixels and touch sensors including an OLED, and includes a display panel that is time-division driven by a display driving period for image display and a touch sensor driving period for touch sensing Wherein the scan driver supplies a data voltage of an input image to data lines of the display panel during the display driving period and supplies a scan pulse synchronized with the data voltage to the scan lines of the display panel, Supplying an AC signal having the same phase as the touch driving signal to the power lines of the data lines, the gate lines, and the pixels during the touch sensor driving period; And supplies the touch driving signal to the touch sensors, Sensing the capacitance change of the sensors.

The present invention provides not only the data lines and the scan lines connected to the pixels but also the power terminals of the pixels in the same phase as the touch driving signal applied to the touch sensors during the touch sensor driving period in which the touch sensing is performed Minimize the effect of parasitic capacitance on the insole touch sensors. Accordingly, the present invention can greatly enhance the touch performance when the inlens touch sensor technology is implemented using the OLED display.

1 is a block diagram schematically showing a touch sensor integrated display device according to the present invention.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a touch sensor integrated type display device.
3 is a view showing a touch sensor of a magneto-capacitance type.
4 is a waveform diagram showing a time-division driving method of the display driving period and the touch sensor driving period.
FIG. 5 is a waveform diagram showing signals applied to an in-line touch sensor, a data line, a gate line, and a pixel power terminal in a display driving period and a touch sensor driving period according to time division driving.
6 is a specific equivalent circuit diagram of one pixel to which the present invention is applied;
Fig. 7 is a diagram showing the parasitic capacitance formed in the pixel of Fig. 6; Fig.
FIG. 8 is a waveform diagram showing signals applied to the pixel of FIG. 6 to minimize the parasitic capacitance of FIG. 7;
FIGS. 9A and 9B are simulation results of the OLED driving current difference immediately before the start of the touch sensor driving period and immediately after the completion of the touch sensor driving period.
10 is a specific equivalent circuit diagram of another pixel to which the present invention is applied;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 and 2 are views showing a touch sensor integrated display device according to the present invention. Fig. 3 shows a capacitive-type touch sensor. 4 shows a time division driving method of the display driving period and the touch sensor driving period. 5 illustrates signals applied to the in-line touch sensor, the data line, the gate line, and the pixel power terminal in the display driving period and the touch sensor driving period according to the time division driving.

1 to 5, the touch sensor integrated type display device of the present invention includes in-line touch sensors. Incel touch sensors are built into the pixel array to sense the touch input.

The touch sensor integrated type display device of the present invention includes a pixel array in which insensitive touch sensors are embedded. This touch sensor integrated type display device is time-division driven by the display driving period Td and the touch sensor driving period Tt. During the display driving period Td, data of the input image is written into the pixel array. During the touch sensor driving period (Tt), the insole touch sensors are driven to detect the touch input.

The in-line touch sensors can be implemented by a capacitive-type touch sensor. The cathode electrode (CAT) of the OLED is divided into in-cell touch sensors (C1 to C4). The present applicant has proposed a technique for patterning a cathode electrode (CAT) to form touch sensors (C1 to C4) through Korean Patent Application No. 10-2015-0076286 (2015/05/29). The present invention simplifies the process by patterning the cathode electrode through the partition walls formed in a mesh shape, and improves the reliability of the process. The prior art invention connects touch sensors to sensor lines through bank holes and contact holes. The present invention increases the reliability of the process of connecting the sensor line to the touch sensor through the contact hole process through the auxiliary electrode. In the present invention, the cross-section of the barrier rib is formed in an inverted taper shape to effectively pattern the cathode electrode. Further, according to the present invention, an undercut structure is formed by disposing one side or both sides of a reverse tapered barrier wall in a bank hole to expand an exposed region of an auxiliary electrode to be connected to a touch sensor in a bank hole region, .

The capacitance of the Insel-touch sensor has a self-capacitance. Each of the self-capacitance-type insole touch sensors (C1 to C4) may be connected to the sensor lines (L1 to L4) according to the process proposed by the present invention. The in-line touch sensors C1 to C4 serve as a cathode electrode (CAT) of the OLED during the display driving period Td.

A low potential power supply voltage VSS which is a DC signal is supplied to the in-line touch sensors C1 to C4 during the display driving period Td and a touch sensor driving signal Tdrv which is an AC signal during the touch sensor driving period Tt . Each of the in-line touch sensors C1 to C4 may be connected to a plurality of pixels.

The touch sensor integrated display of the present invention is implemented as an organic light emitting display (OLED).

In the organic light emitting diode display, the pixel array of the display panel 100 includes pixels defined by data lines (S1 to Sm, m is a positive integer) and gate lines (G1 to Gn, n is a positive integer) (P), in-line touch sensors (C1 to C4) divided from the cathode electrode of the OLED, and sensor wirings (L1 to L4) connected to the in-line touch sensors (C1 to C4). The cathode electrode of the OLED can be formed of a transparent conductive material, for example, ITO (Indium Tin Oxide).

In the pixel array of the display panel 100, each of the gate lines G1 to Gn may include a scan line and an emission line. Each of the pixels P has an OLED and a cell driver (PDC). The cell driver PDC includes a driving TFT DT for controlling the magnitude of the driving current flowing in the OLED and an emission TFT ET for controlling the driving current to flow into the OLED, as shown in FIG. The driving current to be applied to the OLED is determined according to the voltage between the gate and the source of the driving TFT DT. The amount of light emission of the OLED is proportional to the magnitude of the driving current supplied from the driving TFT. The emission TFT ET is connected between the input terminal of the high potential power supply voltage VDD and the input terminal of the low potential power supply voltage VSS and is switched on / off in accordance with the emission pulse from the emission line, . The emission TFT ET is connected between the input terminal of the high potential power supply voltage VDD and the drain electrode of the driving TFT DT (see FIG. 10), or the source electrode of the driving TFT DT and the anode electrode AND) (see FIG. 6).

On the other hand, the cell driver PDC further includes a switching TFT (not shown) for programming the gate-source voltage of the driving TFT DT and at least one storage capacitor for maintaining the programmed voltage for a certain period of time . The switching TFT is turned on according to the scan signal, thereby charging the data voltage from the data line to one electrode of the storage capacitor.

The TFTs constituting the pixel P may be implemented as a P type, an N type, or a hybrid type in which a P type and an N type are mixed. Further, it is preferable that the semiconductor layer of the TFTs constituting the pixel P may include amorphous silicon, polysilicon, or an oxide, and an off-current characteristic thereof may be realized with an oxide having the best off current characteristic .

The touch sensor integrated type display apparatus of the present invention further includes a display driving unit 102, 104, 106, 112 for writing data signals of the input image to the pixels P, and a touch sensor driving unit 110 for driving the touch sensors do.

The driving period of the touch sensor integrated type display device is divided into a display driving period (Td) and a touch sensor driving period (Tt) as shown in FIG. 4 and FIG. The touch sensor driving period Tt may include a vertical blanking period VBT in which the data voltage of the input image is not written to the display panel 100. [

The display driver units 102, 104, 106, and 112 and the touch sensor driver unit 110 are synchronized with each other in response to the synchronization signal Tsync. The first logic level of the synchronization signal Tsync defines the display drive period Td and the second logic level defines the touch sensor drive period Tt. The first logic level may be a high logic level, the second logic level may be a low logic level, or vice versa. In FIG. 5, CAT is a signal waveform applied to the in-line touch sensors.

The display driver 102, 104, 106, and 112 write data of the input image to the pixels P during the display driving period Td. The pixels P hold the data voltage charged in the display driving period Td during the touch sensor driving period Tt since the pixel TFT is in the off state during the touch sensor driving period Tt. The display driver 102, 104, and 106 may apply a touch to minimize the parasitic capacitance between the touch sensors and the signal lines S1 to Sm and G1 to Gn connected to the pixels P during the touch sensor driving period Tt. And supplies the alternating signal Vac having the same phase as the driving signal Tdrv to the signal lines S1 to Sm and G1 to Gn.

The display drivers 102, 104, 106 and 112 include a data driver 102, a gate driver 104, a power supply 112, and a timing controller 106.

The data driver 102 converts the digital video data RGB of the input image received from the timing controller 106 during the display driving period Td into an analog positive / negative gamma compensation voltage to output a data voltage. The data voltage output from the data driver 102 is supplied to the data lines S1 to Sm.

The data driver 102 supplies the AC signal Vac having the same phase as the touch driving signal Tdrv applied to the intellect touch sensors C1 to C4 during the touch sensor driving period Tt to the data lines S1 to Sm, To minimize the parasitic capacitance between the in-cell touch sensors (C1 to C4) and the data lines (S1 to Sm). This is because the voltage across both ends of the parasitic capacitance changes simultaneously and the smaller the voltage difference becomes, the smaller the amount of charge charged in the parasitic capacitance becomes.

The gate driver 104 sequentially supplies scan pulses synchronized with the data voltages to the scan lines during the display driving period Td to select the lines of the display panel 100 in which the data voltages are written. The scan pulse swings between the on level voltage and the off level voltage. A scan pulse is applied to the gate of the pixel TFTs through the scan lines. The ON level voltage applied to the N type switching TFT is a gate high voltage, and the OFF level voltage is a gate low voltage. Conversely, the ON level voltage applied to the P type switching TFT is a gate low voltage, and the OFF level voltage is a gate high voltage. The gate high voltage VGL is set to a voltage higher than the threshold voltage of the pixel TFT and the gate low voltage VGL can be set to a voltage lower than the threshold voltage of the pixel TFT.

The gate driving unit 104 applies the AC signal Vac having the same phase as the touch driving signal Tdrv applied to the touch sensors during the touch sensor driving period Tt to the scan lines to generate a parasitic Minimize capacity. The voltage of the AC signal Vac applied to the scan lines during the touch sensor driving period Tt must be lower than the threshold voltage of the switching TFT so that the data written to the pixels does not change.

On the other hand, the gate driver 104 simultaneously applies emission pulses of off-level during the touch sensor driving period Tt to the emission lines to block the driving current applied to the OLED of the pixels P, And turns off the OLED of the pixels P during the period Tt.

The power supply unit 112 supplies DC power to the power terminals of the pixels P through the power supply lines during the display driving period Td. The power terminal is connected to the OLED during the display driving period Td and includes a first terminal to which the high potential power source voltage VDD is applied and a second terminal to which the reference voltage VREF for initializing the OLED is applied during the display driving period Td As shown in Fig.

The power supply unit 112 applies the AC signal Vac having the same phase as the touch driving signal Tdrv applied to the touch sensors to the power terminal through the power supply line during the touch sensor driving period Tt, And the power supply line.

The timing controller 106 inputs timing signals such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE and a main clock MCLK input from the host system 108 And synchronizes the operation timings of the data driver 102 and the gate driver 104 with each other. The scan timing control signal includes a gate start pulse (GSP), a gate shift clock, a gate output enable signal (GOE), and the like. The data timing control signal includes a source sampling clock (SSC), a polarity control signal (Polarity), a source output enable signal (SOE), and the like.

The host system 108 may be implemented in any one of a television system, a set top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, and a phone system. The host system 108 converts the digital video data of the input image into a format suitable for the resolution of the display panel 100, including a system on chip (SoC) with a built-in scaler. The host system 108 transmits the timing signals Vsync, Hsync, DE, and MCLK to the timing controller 106 together with the digital video data RGB of the input image. The host system 108 also executes an application program associated with coordinate information XY of the touch input input from the touch sensor driver 110. [

The timing controller 106 or the host system 108 may generate a synchronization signal Tsync for synchronizing the display drivers 102, 104, 106 and 112 and the touch sensor driver 110. [

The touch sensor driving unit 110 supplies the touch driving signal Tdrv to the intellect touch sensors C1 to C4 during the touch sensor driving period Tt. The capacitance of the capacitance changes as the conductor, such as a finger, approaches the in-cell touch sensor. The touch sensor driving unit 110 measures the amount of charge change of the insole touch sensor and senses the touch position and the touch area. The touch sensor driver 110 calculates coordinate information XY of each of the touch inputs and transmits them to the host system 108. [

The touch sensor driver 110 supplies a low potential power supply voltage VSS to the intellect touch sensors C1 to C4 during the display driving period Td so that the incelel touch sensors C1 to C4 are connected to the cathode electrodes (CAT).

The data driver 102 and the touch sensor driver 110 may be integrated in one drive IC. This drive IC can be bonded onto the substrate of the display panel 100 by a COG (Chip on Glass) process.

Such a touch sensor integrated type display device of the present invention uses the internal electrode patterning method originally filed by the applicant of the present application to divide the cathode electrode and use it as insensitive touch sensors. In the present invention, the AC signal (Vac) having the same phase as the touch driving signal (Tdrv) applied to the touch sensors during the touch sensor driving period (Tt) is supplied to the power lines Terminals to minimize the effect of parasitic capacitance on the in-cell touch sensors. In general, an organic light emitting display device has a large parasitic capacitance due to a complicated pixel structure and thus has a large influence on a parasitic capacitance applied to an in-cell touch sensor. If the influence of the parasitic capacitance is reduced as described above, the touch sensitivity and accuracy of touch recognition . In order to further reduce the influence of the parasitic capacitance, the present invention proposes to make the touch driving signal Tdrv and the AC signal Vac equal to each other not only in phase but also in amplitude. The amount of charge charged to the parasitic capacitance becomes zero when the both-end voltage of the parasitic capacitance changes simultaneously and there is no voltage difference therebetween. Even if the parasitic capacitance exists physically in the display panel, if the charge amount is not charged to the parasitic capacitance in the above-described manner, the touch performance of the Insel touch sensor is not affected by the parasitic capacitance.

Hereinafter, the operation in the display driving period Td and the touch sensor driving period Tt will be described with reference to one pixel implemented as p-type TFTs and another pixel implemented as n-type TFTs. It should be noted that this pixel configuration is merely an example configuration for facilitating understanding of the present invention, and the technical idea of the present invention is not limited to the specific pixel configuration.

6 is a specific equivalent circuit diagram of one pixel to which the present invention is applied. Fig. 7 shows the parasitic capacitance formed in the pixel of Fig. FIG. 8 shows the signals applied to the pixel of FIG. 6 to minimize the parasitic capacitance of FIG. 9A and 9B show simulation results of the OLED driving current difference immediately before the start of the touch sensor driving period and immediately after the completion of the touch sensor driving period.

6 to 8, one pixel P of the present invention includes an OLED, a driving TFT DT, an emission TFT ET, first to fourth switch TFTs ST1 to ST4, a storage capacitor Cst ). This pixel P is composed of a 6T1C circuit structure including six P-type thin film transistors and one capacitor.

The anode electrode of the OLED is connected to the fourth node N4 and the cathode electrode CAT is connected to the input terminal of the low potential power supply voltage VSS via the first switch SW1 and the second switch SW2 To the input terminal of the touch sensor driving signal Tdrv. The gate electrode of the driving TFT DT is connected to the first node N1, the source electrode thereof is connected to the input terminal of the high potential power supply voltage VDD, and the drain electrode thereof is connected to the third node N3. The gate electrode of the emission TFT ET is connected to the emission line to which the emission pulse EM is supplied, the source electrode thereof is connected to the third node N3, and the drain electrode thereof is connected to the fourth node N4 do. The gate electrode of the first switch TFT (ST1) is connected to the scan line, the source electrode is connected to the data line, and the drain electrode is connected to the second node (N2). The gate electrode of the second switch TFT (ST2) is connected to the scan line to which the scan pulse (SCAN) is supplied, the source electrode is connected to the first node (N1), and the drain electrode is connected to the third node (N3) . The gate electrode of the third switch TFT (ST3) is connected to the emission line to which the emission pulse EM is supplied, the source electrode thereof is connected to the input terminal of the reference voltage VREF, the drain electrode is connected to the second node N2, Respectively. The gate electrode of the fourth switch TFT (ST4) is connected to the scan line to which the scan pulse (SCAN) is supplied, the source electrode thereof is connected to the input terminal of the reference voltage (VREF), and the drain electrode thereof is connected to the fourth node do. The storage capacitor Cst is connected between the first node N1 and the second node N2.

The operation of the pixel P during the display driving period Td will now be described. This pixel structure can compensate the threshold voltage of the driving TFT DT during the display driving period Td.

The display driving period Td is constituted by an initialization period for initializing some nodes of the pixel P, a sampling period for sampling the threshold voltage of the driving TFT DT, and an emission period for emitting OLED.

The scan pulse SCAN is input at the ON level in the initialization period and the sampling period, and then input at the OFF level in the emission period. The emission pulse EM is input at the ON level in the initialization period and the emission period, and is input at the OFF level in the sampling period.

During the initialization period, the third switch TFT (ST3) and the emission TFT (ET) are turned on in response to the on-level emission pulse EM and the first, second and fourth switch TFTs ST4 are turned on in response to the on-level scan pulse SCAN. Therefore, during the initialization period, the voltages of the first to fourth nodes N1 to N4 are initialized to the reference voltage VREF.

During the sampling period, the first, second, and fourth switch TFTs ST1, ST2, and ST4 maintain the turn-on state in response to the scan pulse SCAN of the ON level, The switching TFT ET is turned off in response to the off-level emission pulse EM. During the sampling period, the data voltage VDATA is applied to the second node N2 through the data line and the first switch TFT (ST1). During the sampling period, the potentials of the first and third nodes N1 and N3 become "VDD-Vth ". Vth indicates the threshold voltage of the driving TFT DT.

During the emission period, the first, second and fourth switch TFTs ST1, ST2 and ST4 are turned off in response to the off-level scan pulse SCAN, and the third switch TFT ST3 and the emission TFT ET Is turned on in response to the on-level emission pulse EM. The reference voltage VREF is applied to the second node N2 during the emission period and the potential change VREF-VDATA of the second node N2 is reflected to the first node N1. During the emission period, the potential of the first node N1 is programmed to "(VDD-Vth) + (VREF-VDATA) ". Therefore, during the emission period, the gate-source voltage Vgs of the driver TFT DT is programmed to "VDATA-VREF + Vth ". The driving current Ioled relation is k / 2 (Vgs-Vth) ^2. Since Vth is included in the programmed Vgs, the Vth component is canceled in the driving current (Ioled) relation. Therefore, the influence of the change in the threshold voltage Vth on the drive current Ioled is eliminated.

Meanwhile, during the display driving period Td, a low potential power supply voltage VSS is supplied to the cathode electrode CAT of the OLED through the first switch SW1. The first switch SW1 is turned on by the first control signal VMUX of the ON level during the display driving period Td. The first control signal VMUX may have a phase opposite to the synchronization signal Tsync.

Next, the operation of the pixel P during the touch sensor driving period Tt will be described.

The touch sensor driving signal Tdrv is supplied to the cathode electrode CAT of the OLED through the second switch SW2 and the cathode electrode CAT is operated as the touch sensor during the touch sensor driving period Tt. The second switch SW2 is turned on by the second control signal VMUXB of the on level during the touch sensor driving period Tt. The second control signal VMUXB may have the same phase as the synchronization signal Tsync.

When a conductive object such as a finger touches the touch sensor CAT, the capacitance of the touch sensor CAT is changed by the contact capacitance Cf, and the touch is sensed based on the change amount. However, since the touch sensor CAT is formed to overlap with the signal lines and the power supply terminals of the pixels P, much parasitic capacitance due to coupling occurs at the overlapped portion. The parasitic capacitance includes a first parasitic capacitance C1 between the touch sensor CAT and a reference voltage VREF input terminal, a second parasitic capacitance C2 between the touch sensor CAT and the data line, a touch sensor CAT, The fourth parasitic capacitance C4 between the touch sensor CAT and the emission line and the fifth parasitic capacitance C5 between the input terminal of the touch sensor CAT and the high potential power supply voltage VDD, . This parasitic capacitance affects the touch sensor (CAT), and the amount of capacitance change due to the touch is reduced, thereby deteriorating the touch performance. That is, if the influence of the parasitic capacitance is large, the touch sensitivity and accuracy of the touch recognition deteriorate.

During the touch sensor driving period Tt, parasitic capacitance with the touch sensor CAT is minimized at the input terminal of the reference voltage VREF, the data line, the scan line, the emission line, and the high potential power supply voltage VDD The AC signal Vac is applied. It is preferable that the AC signal Vac has the same phase and the same amplitude (VTX) as the touch driving signal Tdrv.

During the touch sensor driving period (Tt), since the touch signal (Tdrv), which is an AC signal, is applied to the cathode electrode (CAT) of the OLED, the light emitting operation of the OLED may become unstable. Accordingly, in the present invention, during the touch sensor driving period Tt, the emission pulse EM is turned off to prevent the unstable light emission by turning off the emission TFT (ET) of the pixels P.

The luminance drift may occur in the neighboring display driving periods Td with the touch sensor driving period Tt in between, due to non-light emission during the touch sensor driving period Tt. However, such a luminance deviation is not so large because the touch sensor driving period Tt is very short, and can be neglected when a pixel circuit is constituted by an oxide TFT having a good leakage current characteristic. As a result of the simulation, it was found that the OLED driving current difference just before the start of the touch sensor driving period and immediately after the completion of the touch sensor driving period is negligible with respect to the data voltage and the threshold voltage compensation effect, as shown in FIGS. 9A and 9B.

10 is a specific equivalent circuit diagram of another pixel to which the present invention is applied.

10, another pixel P of the present invention includes an OLED, a driving TFT DT, an emission TFT ET, first and second switch TFTs ST1 and ST2, first and second storage capacitors (Cst1, Cst2). This pixel P is a 4T2C circuit structure including four N-type thin film transistors and two capacitors, and can compensate the threshold voltage of the driving TFT DT during the display driving period Td.

The specific compensation operation of this pixel P during the display driving period Td is described in detail in Korean Patent Application No. 10-2014-0192641 (2014/12/29), which is filed by the present applicant.

In the pixel P, the input terminals of the reference voltage VREF, the data lines, the first and second scan lines, the emission lines, and the high potential power supply voltage VDD are connected to the input terminals of the reference voltage VREF during the touch sensor driving period Tt The AC signal Vac for minimizing the parasitic capacitance with the touch sensor CAT is applied. It is preferable that the AC signal Vac has the same phase and the same amplitude (VTX) as the touch driving signal Tdrv.

As described above, according to the present invention, an AC signal having the same phase as that of a touch driving signal applied to the touch sensors during a touch sensor driving period in which the touch sensing is performed is applied to not only the data lines and the scan lines connected to the pixels, Terminals to minimize the effect of parasitic capacitance on the in-cell touch sensors. Accordingly, the present invention can greatly enhance the touch performance when the inlens touch sensor technology is implemented using the OLED display.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, 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.

100: display panel 102: data driver
104: Gate driver 106: Timing controller
110: touch sensor driving unit 112: power supply unit

Claims (14)

A display panel which is time-divisionally driven by a display driving period for image display and a touch sensor driving period (Tt) for touch sensing, the touch sensor being implemented by patterning pixels including OLED and a cathode electrode of the OLED;
A touch sensor driver for sensing a change in capacitance of the touch sensors by supplying a touch driving signal to the touch sensors during the touch sensor driving period;
A data driver for supplying a data voltage of an input image to the data lines of the display panel during the display driving period and supplying an AC signal having the same phase as the touch driving signal to the data lines during the touch sensor driving period;
A gate driver for supplying a scan pulse synchronized with the data voltage to the scan lines of the display panel during the display driving period and supplying the AC signal to the scan lines during the touch sensor driving period; And
And supplies a reference voltage to an input terminal of a reference voltage connected to the OLED of the pixels while supplying a high potential power supply voltage to an input terminal of a high potential supply voltage connected to the driver TFT of the pixels during the display driving period, And a power supply unit for supplying an AC signal having the same phase as the touch driving signal to an input terminal of the high potential power supply voltage and an input terminal of the reference voltage,
The cathode electrode of the OLED is connected to an input terminal of a low potential power supply voltage through a first switch and is connected to an input terminal of the touch driving signal through a second switch which is switched in reverse to the first switch, Is turned on only during the display driving period, and the second switch is turned on only during the touch sensor driving period. The method according to claim 1,
And the OLED of the pixels maintains a turn-off state during the touch sensor driving period. 3. The method of claim 2,
Wherein the gate driver simultaneously applies an emission pulse of an off level to the emission lines during the touch sensor driving period to block a driving current applied to the OLED of the pixels. The method according to claim 1,
Wherein the touch sensor driver supplies a low potential power supply voltage in the form of a DC power source to the touch sensors during the display driving period. delete The method according to claim 1,
Wherein the touch sensor driving period includes a vertical blank period in which the data voltage of the input image is not written to the display panel. The method according to claim 1,
Wherein the AC signal has the same amplitude as the touch driving signal. delete delete delete delete delete delete delete

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