KR102009888B1 - Electronic device having a touch sensor and driving method thereof - Google Patents

Abstract

The present invention relates to a touch screen including touch sensors defined by Tx lines and Rx lines; A touch sensing circuit configured to supply driving signals to the Tx lines and sense voltage changes of the touch sensors through the Rx lines; And a touch coordinate detection unit configured to detect a touch input position by comparing a change in the voltage sensed by the touch sensing circuit with a touch threshold value, wherein the touch sensing circuit forms an overdriving voltage higher than a charging voltage in a charging section of the driving signal. The present invention provides an electronic device having a touch sensor including a charge and discharge circuit that forms an underdriving voltage lower than a reference voltage in a discharge period of a driving signal.

Description

ELECTRONIC DEVICE HAVING A TOUCH SENSOR AND DRIVING METHOD THEREOF

The present invention relates to an electronic device having a touch sensor and a driving method thereof.

BACKGROUND In various electronic devices such as home appliances and portable information devices, user input means have been replaced by touch sensors in button-type switches according to the trend of light weight and slimness. Accordingly, recently released electronic devices such as display devices have a touch sensor (or touch screen).

The capacitive type touch sensor, which is one of the touch sensors, may detect the presence and coordinate of a touch by sensing a change in mutual capacitance when a human finger or a conductive material contacts or approaches. In this case, in order to measure a change in mutual capacitance and determine information on a touch, each sensor node of the touch screen panel is set, a driving signal is output, a change in mutual capacitance of the touch screen panel is sensed, and the data is binarized. The process goes on.

Meanwhile, in the electronic device having a conventional touch sensor, when the switch is cut off and the driving signal is charged in the RC (R: resistance, C: capacitor) circuit in a discharged state, the voltage applied to the circuit increases along the RC time constant. . On the contrary, when the driving signal is charged and the RC circuit is cut off and discharged, the discharge is performed according to the RC time constant.

This phenomenon is inherent in response to the RC delay of the sensing electrode formed on the Tx line. As the distance from the driving signal input terminal of the Tx line increases, the slope of the signal lies down. In order to improve this, a method of lowering the frequency of the driving signal supplied through the Tx line may be used. However, if the RC value is increased, the method of lowering the frequency becomes useless. Therefore, the electronic device having the conventional touch sensor should improve the problem that the driving time is stabilized by the RC delay and the sensing speed is lowered.

The present invention for solving the above problems of the background art is to form a charge and discharge time of the touch sensor of the touch screen quickly and uniformly, and to provide an electronic device and a driving method thereof having a touch sensor that can improve the touch sensitivity and touch speed To provide.

The present invention provides a touch screen including touch sensors defined by Tx lines and Rx lines. A touch sensing circuit configured to supply driving signals to the Tx lines and sense voltage changes of the touch sensors through the Rx lines; And a touch coordinate detection unit configured to detect a touch input position by comparing a change in the voltage sensed by the touch sensing circuit with a touch threshold value, wherein the touch sensing circuit forms an overdriving voltage higher than a charging voltage in a charging section of the driving signal. The present invention provides an electronic device having a touch sensor including a charge and discharge circuit that forms an underdriving voltage lower than a reference voltage in a discharge period of a driving signal.

The charging / discharging circuit unit may vary the time for forming the overdriving voltage and the underdriving voltage according to the wiring length of the Tx lines.

The charge / discharge circuit unit may vary the level at which the overdriving voltage and the underdriving voltage are formed according to the wiring length of the Tx lines.

As the wiring length of the Tx lines increases, the charge / discharge circuit unit may increase the weight of the time or level at which the overdriving voltage and the underdriving voltage are formed.

The charge / discharge circuit unit may configure the Tx lines in groups of M (M is an integer of 2 or more), and may vary the time or level at which the overdriving voltage and the underdriving voltage are formed for each of the M groups.

The charging / discharging circuit unit may form an overdriving voltage in the driving signal when the edge of the driving signal is in a rising state, and may form an underdriving voltage in the driving signal when the edge of the driving signal is in a falling state.

The charge / discharge circuit unit includes a drive signal generator for generating a drive signal to be output through the Tx lines, a power supply unit for converting a high potential voltage supplied from the outside into two or more positive voltages and one or more negative voltages, and driving the drive signal; It may include a selection signal output unit for detecting a signal and outputting a selection signal in response to the detected result, and a voltage selection unit for selectively outputting one of the voltages output from the power supply in response to the selection signal.

The selection signal output unit may detect an edge of the driving signal and vary the selection signal so that the overdriving voltage and the underdriving voltage are separately formed according to the wiring length of the Tx lines.

The voltage selector may form an overdriving voltage in the driving signal when the selection signal is 01, form an underdriving voltage in the driving signal when the selection signal is 11, and form a charging voltage in the driving signal when the selection signal is 00.

In another aspect, the present invention provides a touch screen including touch sensors defined by Tx lines and Rx lines, and a touch sensing circuit that supplies a driving signal to the Tx lines and senses a voltage change of the touch sensors through the Rx lines. A method of driving an electronic device having a touch sensor, the method comprising: detecting an edge of a driving signal supplied through Tx lines; Determining whether an edge of the driving signal is in a rising state or a falling state; And forming an overdriving voltage in the driving signal when the edge of the driving signal is in the rising state, and forming an underdriving voltage in the driving signal when the edge of the driving signal is in the falling state. to provide.

The present invention provides an electronic device having a touch sensor capable of quickly and uniformly forming a charge / discharge time of touch sensors of a touch screen by improving the difference in charging or discharging time according to RC delay characteristics, and improving touch sensitivity and touch speed. It is effective to provide a driving method.

1 illustrates an electronic device having a touch sensor according to an embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram of the touch screen shown in FIG. 1.
3 to 5 illustrate various combinations of a liquid crystal display panel and a touch screen.
6 is a diagram for explaining an RC delay occurring in a touch screen.
7 is an exemplary configuration of a Tx driving circuit according to the first embodiment of the present invention.
8 is a view for explaining the operation of the Tx driving circuit shown in FIG.
9 is an exemplary waveform diagram of a drive signal output from a Tx drive circuit.
10 illustrates an output waveform of a drive signal according to a selection signal.
11 illustrates an output waveform of a drive signal according to an RC delay characteristic.
12 is an exemplary configuration diagram of a Tx driving circuit according to a second embodiment of the present invention.
13 is an exemplary waveform diagram of a drive signal output from a Tx drive circuit.
14 is a view for explaining a method of driving an electronic device having a touch sensor according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, the specific content for the practice of the present invention will be described.

1 is a diagram illustrating an electronic device having a touch sensor according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the touch screen shown in FIG. 1, and FIGS. 3 to 5 are various views of a liquid crystal display panel and a touch screen. 6 illustrates a combination form, and FIG. 6 is a diagram for describing an RC delay occurring in a touch screen.

An electronic device having a touch sensor of the present invention is implemented as a television, a set top box, a navigation, a video player, a Blu-ray player, a personal computer (PC), a home theater and a mobile phone. An electronic device having a touch sensor of the present invention is implemented based on a display panel. The display panel may be a flat panel display panel such as a liquid crystal display panel, an organic light emitting display panel, an electrophoretic display panel, a plasma display panel, but is not limited thereto. However, in the following description, a liquid crystal display panel is described as an example for convenience of description.

An electronic device having a touch sensor includes a host system 50, a timing controller 20, a data driving circuit 12, a scan driving circuit 14, a liquid crystal display panel DIS, a touch screen TSP, and a touch screen driving circuit. (30, 40).

The host system 50 includes a system on chip (SoC) incorporating a scaler, which converts digital video data RGB of an input image into a format suitable for displaying on a display panel DIS. The host system 50 transmits timing signals Vsync, Hsync, DE, and MCLK together with the digital video data to the timing controller 20. The host system 50 executes an application program associated with the coordinate information XY of the touch input position input from the touch coordinate detector 40.

The timing controller 20 receives timing signals such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal Data Enable, DE, and a main clock MCLK from the host system 50. Based on this, the data driving circuit 12 and the scan driving circuit 14 are controlled.

The timing controller 20 is a scan driving circuit based on scan timing control signals such as a gate start pulse (GSP), a gate shift clock, and a gate output enable signal (GOE). (14). The timing controller 20 is a data driving circuit based on data timing control signals such as a source sampling clock (SSC), a polarity control signal (Polarity, POL), and a source output enable signal (SOE). To control (12).

The data driving circuit 12 converts the digital video data RGB input from the timing controller 20 into an analog positive / negative gamma compensation voltage to generate a data voltage. The data driving circuit 12 supplies a data voltage through the data lines D1 to Dm.

The scan driving circuit 14 sequentially generates gate pulses (or scan pulses) synchronized with the data voltages. The scan driving circuit 14 supplies a gate pulse through the gate lines G1 to Gn.

The liquid crystal display panel DIS displays an image based on the gate pulse supplied from the scan driving circuit 14 and the data voltage supplied from the data driving circuit 12. The liquid crystal display panel DIS includes a liquid crystal layer formed between two substrates GLS1 and GLS2. The liquid crystal display panel DIS may be implemented in any known liquid crystal mode, such as a twisted nematic (TN) mode, a vertical alignment (VA) mode, an in plane switching (IPS) mode, and a fringe field switching (FFS) mode.

The subpixels of the liquid crystal display panel DIS are defined by data lines D1 to Dm, where m is a positive integer, and gate lines G1 to Gn, where n is a positive integer. One subpixel is a thin film transistor (TFT) formed at intersections of the data line and the gate line, a pixel electrode for charging a data voltage, and a storage capacitor connected to the pixel electrode to maintain the voltage of the liquid crystal cell. ), And the like.

A black matrix, a color filter, and the like are formed on the upper substrate GLS1 of the liquid crystal display panel DIS. The lower substrate GLS2 of the liquid crystal display panel DIS may be implemented in a color filter on TFT (COT) structure. In this case, the black matrix and the color filter may be formed on the lower substrate GLS2 of the liquid crystal display panel DIS. The common electrode supplied with the common voltage may be formed on the upper substrate GLS1 or the lower substrate GLS2 of the liquid crystal display panel DIS. Polarizing plates POL1 and POL2 are attached to the upper substrate GLS1 and the lower substrate GLS2 of the liquid crystal display panel DIS, and an alignment layer for setting the pretilt angle of the liquid crystal is formed on the inner surface of the liquid crystal display panel DIS.

A column spacer for maintaining a cell gap of the liquid crystal cell is formed between the upper substrate GLS1 and the lower substrate GLS2 of the liquid crystal display panel DIS. The backlight unit is disposed under the rear surface of the lower polarizer POL2 of the liquid crystal display panel DIS. The backlight unit is implemented in an edge type or a direct type to provide light to the liquid crystal display panel DIS.

The touch screen TSP includes Tx lines (Tx1 to Txj, j is a positive integer smaller than n), and Rx lines (Rx1 to Rxi and i are positive amounts smaller than m) intersecting the Tx lines (Tx1 to Txj). Integer), and i × j touch sensors Cts formed at intersections of the Tx lines Tx1 to Txj and the Rx lines Rx1 to Rxi. The touch sensors Cts each include a capacitance when viewed in an equivalent circuit.

The capacitance can be classified into a self capacitance or a mutual capacitance. The self capacitance is formed along a single layer of conductor wiring formed in one direction. Mutual capacitance is formed between two orthogonal conductor wires. The embodiment illustrates a mutual capacitive touch screen, but the present invention is not limited thereto.

The touch screen TSP may be implemented to be positioned on the upper polarizer POL1 of the liquid crystal display panel DIS as shown in FIG. 3. The touch screen TSP may be implemented to be positioned between the upper polarizing plate POL1 and the upper substrate GLS1 of the liquid crystal display panel DIS as shown in FIG. 4. As illustrated in FIG. 5, the touch screen TSP may be implemented in such a manner that the pixel electrode PIX and the touch sensor Cts of the lower substrate GLS2 are located together to be embedded in the liquid crystal display panel DIS.

The touch screen driving circuits 30 and 40 supply a driving signal to the touch sensors Cts to sense a voltage change of the touch sensor before and after the touch input, and compare the voltage change with a predetermined touch threshold value to determine the touch input position. Detect. The touch screen driving circuits 30 and 40 calculate coordinates of the touch input position.

The touch sensing circuit 30 includes a Tx driving circuit 32, an Rx driving circuit 34, a Tx / Rx controller 38, and the like. The touch sensing circuit 30 applies a driving signal to the touch sensors Cts through the Tx lines Tx1 to Txj using the Tx driving circuit 32, and Rx lines Rx1 to synchronously with the driving signal. The touch raw data is output by sensing the voltages of the touch sensors Cts through Rxi and Rx driving circuit 34. The driving signal may be formed in various forms such as a pulse, a sinusoidal wave, and a triangular wave. The touch sensing circuit 30 may be integrated into one read-out integrated circuit (ROIC).

The Tx driving circuit 32 selects a Tx channel for outputting a driving signal in response to the Tx setup signal from the Tx / Rx controller 38 and applies the driving signal to the Tx lines Tx1 to Txj connected to the selected Tx channel. Is authorized. The Tx lines Tx1 to Txj are charged during the high potential period of the driving signal to supply charge to the touch sensors Cts. The driving signal is connected to the Tx lines Tx1 to Txj so that the voltages of the touch sensors Cts are accumulated on the capacitor of the integrator built in the Rx driving circuit 34 through the Rx lines Rx1 to Rxi. N (N is a positive integer above) can be supplied continuously to each.

The Rx driving circuit 34 selects Rx lines to receive the voltage of the touch sensor in response to the Rx setup signal from the Tx / Rx controller 38, and touches the touch sensor Cts through the selected Rx lines in synchronization with the driving signal. Receive and sample the output voltage of. The Rx driving circuit 34 accumulates the sampled voltage in the integrator capacitor, converts the voltage of the capacitor into digital data using an analog-to-digital converter (hereinafter referred to as "ADC"), and Digital data is output as touch raw data.

The Tx / Rx controller 38 controls the Tx channel and Rx channel settings in response to the Tx setup signal and the Rx setup signal from the touch coordinate detector 40 and synchronizes the Tx driver 32 and the Rx driver 34.

The touch coordinate detector 40 supplies the Tx setup signal and the Rx setup signal to the Tx / Rx controller 38 and supplies the ADC clock signal for operating the ADC of the Rx driver circuit 34 to the Rx driver circuit 34. . The touch coordinate detector 40 compares the touch raw data with a preset touch threshold value. The touch coordinate detector 40 determines only the touch threshold value or more of the touch raw data as the touch data obtained from the touch sensors Cts.

The touch coordinate detector 40 assigns an identification number to each of the touch data having a touch threshold value or more, calculates coordinates for each of the touch input positions, and transmits each identification number and coordinate information XY to the host system 50. send. The touch coordinate detector 40 may be implemented as a micro controller unit (MCU).

Meanwhile, in the electronic device having the touch sensor, as shown in FIG. 6, the RC (R: resistance, C: capacitor) delay value of the region adjacent to the first Tx line Tx1 and the RC delay value of the region adjacent to the jTx line Txj are different from each other. different. Specifically, since the first Tx line Tx1 is adjacent to the touch sensing circuit 30, the length of the wiring is shorter than that of the jTx line Txj. Therefore, the RC time constant of the first Tx line Tx1 is smaller than the jTx line Txj. On the other hand, since the jTx line Txj is not adjacent to the touch sensing circuit 30, the length of the wiring is longer than that of the first Tx line Tx1. Therefore, the RC time constant of the jTx line Txj is larger than the first Tx line Tx1.

In the above description, the first Tx line Tx1 wired closest to the touch sensing circuit 30 and the jTx line Txj wired farthest are extremely described. According to this description, the RC time constants of the Tx lines Tx1 to Txj become smaller as they are adjacent to the first Tx line Tx1 and become larger as they become adjacent to the jTx line Txj. As such, the RC delay characteristic existing between the Tx lines Tx1 to Txj causes a difference in charging or discharging time, resulting in a long time for stabilizing a driving signal and a decrease in sensing speed.

The present invention is configured as follows to improve the RC delay characteristics present between the Tx lines Tx1 to Txj.

First Embodiment

FIG. 7 is a diagram illustrating a configuration of a Tx driving circuit according to a first embodiment of the present invention, FIG. 8 is a view for explaining an operation of the Tx driving circuit shown in FIG. 7, and FIG. 9 is output from a Tx driving circuit. 10 is an exemplary waveform diagram of a driving signal, and FIG. 10 is an exemplary diagram illustrating an output waveform of a driving signal according to a selection signal, and FIG. 11 is an exemplary diagram illustrating an output waveform of a driving signal according to an RC delay characteristic.

The Tx driving circuit 32 according to the first embodiment of the present invention includes charge and discharge circuits 131, 132, 133, 135, 137, and 139 for improving RC delay characteristics. The charge / discharge circuit unit 131, 132, 133, 135, 137, and 139 includes a drive signal generator 131, a selection signal output unit 132, a level shifter 133, a power supply unit 135, and a power stabilization unit ( 137 and a voltage selector 139 are included.

The driving signal generator 131 generates a driving signal Tx pulse to be output through the Tx lines Tx1 to Txj. The driving signal generator 131 generates and outputs a driving signal Tx pulse in a pulse form.

The power supply 135 converts the external voltage VCC supplied from the outside into a first positive voltage Vo ', a second positive voltage 2Vo', a first negative voltage -Vo ', and the like. Output The second positive voltage 2Vo 'is a positive voltage higher than the first positive voltage Vo' and the first negative voltage -Vo 'is a negative voltage lower than the first positive voltage Vo'. Is selected. The power supply unit 135 may be configured as a charge pump, but is not limited thereto.

The power stabilization unit 137 may adjust the first positive voltage Vo ', the second positive voltage 2Vo' and the first negative voltage −Vo ′ output from the power supply 135. The voltage Vo is stabilized with the second positive voltage 2Vo and the first negative voltage -Vo and then output. The power stabilizer 137 may be formed of an LDO regulator or a passive element, but is not limited thereto. On the other hand, when the first positive voltage (Vo '), the second positive voltage (2Vo') and the first negative voltage (-Vo ') output from the power supply unit 135 is stably output, the power stabilizer ( 137 may be omitted.

The voltage selector 139 selectively outputs the voltage output from the power supply unit 135 or the power stabilization unit 137 in response to the selection signal Sel output from the selection signal output unit 132. The voltage selector 139 may be implemented as a multiplexer that outputs a plurality of voltages or signals as one voltage or signal, but is not limited thereto.

The selection signal output unit 132 detects the driving signal Tx pulse output from the driving signal generator 131 and outputs a selection signal Sel corresponding to the detected result. The selection signal output unit 132 has a voltage selector 139 having a first positive voltage Vo, a second positive voltage 2Vo and a first negative voltage according to the edge of the driving signal Tx pulse. A select signal Sel is output to output one of Vo. In addition, the selection signal output unit 132 counters the set time such that the voltage output from the voltage selection unit 139 is maintained for a predetermined time.

For example, as shown in FIG. 8, the selection signal output unit 132 outputs 01 when the edge of the driving signal Tx Pulse is in the rising state and 11 when the edge of the driving signal Tx Pulse is in the polling state. At this time, the selection signal output unit 132 counts a predetermined time so that the voltage output from the voltage selection unit 139 is maintained for a predetermined time to maintain 01 or 11 for a predetermined time and then maintain 00. For example, the selection signal output unit 132 counts a predetermined time, and when the value of the counter becomes 0, switches the state of the selection signal Sel from 01 to 00, or from 11 to 00 of the selection signal Sel. Toggle state.

As can be seen from the above description, the selection signal output unit 132 includes a signal detection unit for detecting the edge of the driving signal (Tx Pulse) and outputting the selection signal and a signal counter unit for maintaining the selection signal for a predetermined time.

The driving signal Tx Pulse includes the overdriving voltage ODP and the underdriving voltage UDP as shown in FIG. 9 by the above-described charge / discharge circuit units 131, 132, 133, 135, 137, and 139. The driving signal Tx Pulse is output in the form of alternating charging and discharging based on the reference voltage (0V). When the overdriving voltage ODP and the underdriving voltage UDP are formed in the driving signal Tx pulse under the conditions as shown in FIG. 9, the selection signal Sel is output as shown in FIG. 10.

The overdriving voltage ODP forms a higher voltage than the charging voltage Vo in the charging section of the driving signal Tx pulse to accelerate the charging time. On the other hand, the underdriving voltage UDP forms a voltage lower than the reference voltage 0V in the discharge section of the driving signal Tx pulse to accelerate the discharge time. Therefore, the selection signal output unit 132 detects the edge of the driving signal Tx Pulse and separates the overdriving voltage ODP and the underdriving voltage UDP according to the wiring lengths of the Tx lines Tx1 to Txj. The selection signal Sel is varied to be formed.

As described above, the RC delay characteristic existing between the Tx lines Tx1 to Txj causes a difference in charging or discharging time, thereby increasing the time for stabilizing the driving signal and decreasing the sensing speed. However, this problem can be solved by forming the overdriving voltage ODP in the charging section of the driving signal Tx Pulse and forming the underdriving voltage UDP in the discharging section of the driving signal Tx Pulse. Will be. This is because the charges of the touch sensors are charged within a short time by the overdriving voltage ODP and the charges of the touch sensors are discharged within a short time by the underdriving voltage UDP.

Therefore, when the driving signal (Tx Pulse) is output in the form of the present invention, the charge and discharge time of the touch sensors of the large area touch screen with a large RC delay can be formed quickly and uniformly. As a result, the present invention can improve the touch sensitivity and the touch speed.

Meanwhile, the RC delay characteristic is different depending on the Tx lines Tx1 to Txj. Therefore, the time (or width) at which the overdriving voltage ODP and the underdriving voltage UDP are formed may be adjusted according to the positions of the Tx lines Tx1 to Txj.

For example, FIG. 11A is applied to a Tx line having a relatively low RC delay characteristic. On the other hand, FIG. 11B is applied to a Tx line having a relatively high RC delay characteristic. In FIGS. 11A and 11B, the widths W1 and W2 in which the overdriving voltage ODP and the underdriving voltage UDP are formed as the RC delay characteristics are high and low are different. In other words, the Tx line close to the touch sensing circuit has a small RC time constant. Therefore, the driving signal Tx pulse of FIG. 11A is applied. In contrast, the Tx line far from the touch sensing circuit has a large RC time constant. Therefore, the driving signal Tx pulse of FIG. 11B is applied.

In the first embodiment of the present invention, two cases in which the overdriving voltage ODP and the underdriving voltage UDP are formed are more than the first width W1 and the second width W2. . However, the width (or time) at which they are formed may be subdivided into K (K is an integer of 2 or more) corresponding to the RC delay characteristics. In this case, as the wiring length of the Tx lines becomes longer, the weight of the width (or time) at which the overdriving voltage ODP and the underdriving voltage UDP are formed may increase.

Meanwhile, the time (or width) at which the overdriving voltage ODP and the underdriving voltage UDP are formed may be adjusted by the selection signal output unit 132. In this case, the selection signal output unit 132 may vary the counter value for each Tx line in order to adjust the voltage according to the RC value for each Tx line. However, in this case, since the number of variables for setting the counter value increases, the Tx lines may be configured into M groups (M is an integer greater than or equal to 2) and the counter values may be changed corresponding to the M groups.

Second Embodiment

12 is an exemplary configuration diagram of a Tx driver circuit according to a second embodiment of the present invention, and FIG. 13 is an exemplary diagram of waveforms of a drive signal output from the Tx driver circuit.

The Tx driving circuit 32 according to the second embodiment of the present invention includes charge and discharge circuits 131, 132, 133, 135, 137, and 139 for improving RC delay characteristics. The charge / discharge circuit unit 131, 132, 133, 135, 137, and 139 includes a drive signal generator 131, a selection signal output unit 132, a level shifter 133, a power supply unit 135, and a power stabilization unit ( 137 and a voltage selector 139 are included.

The driving signal generator 131 generates a driving signal Tx pulse to be output through the Tx lines Tx1 to Txj. The driving signal generator 131 generates and outputs a driving signal Tx pulse in a pulse form.

The power supply unit 135 supplies the external voltage VCC supplied from the outside to the first positive voltage Vo ', the second positive voltage 2Vo', the third positive voltage 3Vo ', and the first negative voltage. The voltage is converted into the voltage (-Vo ') and the second negative voltage (-2Vo') and the like. The third positive voltage 3Vo 'is selected as a positive voltage higher than the second positive voltage 2Vo', and the second positive voltage 2Vo 'is positive than the first positive voltage Vo'. Is selected as the voltage. The first negative voltage (-Vo ') is selected as a negative voltage lower than the first positive voltage (Vo'), and the second negative voltage (-2Vo ') is the first negative voltage (-Vo'). It is selected with a lower negative voltage. The power supply unit 135 may be configured as a charge pump, but is not limited thereto.

The power stabilizer 137 may include the first positive voltage Vo ′, the second positive voltage 2Vo ′, the third positive voltage 3Vo ′, and the first negative voltage output from the power supply 135. (-Vo ') and the second negative voltage (-2Vo') are the first positive voltage (Vo), the second positive voltage (2Vo), the third positive voltage (3Vo), and the first negative voltage ( -Vo) and the second negative voltage (-2Vo) is stabilized and output. The power stabilizer 137 may be formed of an LDO regulator or a passive element, but is not limited thereto. On the other hand, the first positive voltage (Vo '), the second positive voltage (2Vo'), the third positive voltage (3Vo '), the first negative voltage (-Vo') output from the power supply unit 135 The power stabilizer 137 may be omitted when the second negative voltage (−2Vo ′) is stably output.

The voltage selector 139 selectively outputs the voltage output from the power supply unit 135 or the power stabilization unit 137 in response to the selection signal Sel output from the selection signal output unit 132. The voltage selector 139 may be implemented as a multiplexer that outputs a plurality of voltages or signals as one voltage or signal, but is not limited thereto.

The selection signal output unit 132 detects the driving signal Tx pulse output from the driving signal generator 131 and outputs a selection signal Sel corresponding to the detected result. The selection signal output unit 132 has a voltage selector 139 having a first positive voltage Vo, a second positive voltage 2Vo, and a third positive voltage 3Vo according to the edge of the driving signal Tx pulse. ), The selection signal Sel is output to output one of the voltage of the first sound (-Vo) and the voltage of the second sound (-2Vo). In addition, the selection signal output unit 132 counters the set time such that the voltage output from the voltage selection unit 139 is maintained for a predetermined time.

The first and second overdriving voltages ODP and the first and second underdrives are included in the driving signal Tx pulse by the charge and discharge circuit unit 131, 132, 133, 135, 137, and 139 described above. The driving voltage UDP is included. The driving signal Tx Pulse is output in the form of alternating charging and discharging based on the reference voltage (0V).

The first and second overdriving voltages ODP form a voltage higher than the charging voltage Vo in the charging section of the driving signal Tx pulse to accelerate the charging time. On the other hand, the first and second underdriving voltages UDP form a voltage lower than the reference voltage 0V in the discharge period of the driving signal Tx pulse to accelerate the discharge time.

As described above, the RC delay characteristic existing between the Tx lines Tx1 to Txj causes a difference in charging or discharging time, thereby increasing the time for stabilizing the driving signal and decreasing the sensing speed. However, as shown in the present invention, the first and second overdriving voltages ODP are formed in the charging section of the driving signal Tx Pulse, and the first and second underdriving voltages UDP in the discharging section of the driving signal Tx Pulse. Can be solved. The reason is that the charges of the touch sensors are charged in a short time by the first and second overdriving voltages ODP and the charges of the touch sensors are discharged in a short time by the first and second underdriving voltages UDP.

Therefore, when the driving signal (Tx Pulse) is output in the form of the present invention, the charge and discharge time of the touch sensors of the large area touch screen with a large RC delay can be formed quickly and uniformly. As a result, the present invention can improve the touch sensitivity and the touch speed.

Meanwhile, the RC delay characteristic is different depending on the Tx lines Tx1 to Txj. Therefore, the period in which the first and second overdriving voltages ODP and the first and second underdriving voltages UDP are formed may be adjusted according to the positions of the Tx lines Tx1 to Txj.

For example, the Tx line close to the touch sensing circuit has a small RC time constant. Therefore, only the first overdriving voltage ODP1 and the first underdriving voltage UDP1 are applied to the Tx line close to the touch sensing circuit. In contrast, the Tx line far from the touch sensing circuit has a large RC time constant. Therefore, the first and second overdriving voltages ODP and the first and second underdriving voltages UDP are applied to the Tx line far from the touch sensing circuit.

In the second embodiment of the present invention, a Tx line in which the first overdriving voltage ODP and the first underdriving voltage UDP are formed, the first and second overdriving voltage ODP, and the first and the first Two examples of the Tx line in which the two underdriving voltages UDP are formed are illustrated. However, they may be subdivided into L overload voltages ODP and underdriving voltages UDP corresponding to RC delay characteristics. At this time, the longer the wiring length of the Tx lines, the higher the weight of the level at which the overdriving voltage ODP and the underdriving voltage UDP are formed.

Meanwhile, a Tx line in which the first overdriving voltage ODP and the first underdriving voltage UDP are formed, and the first and second overdriving voltage ODP and the first and second underdriving voltage UDP are formed. The Tx line may be adjusted by the selection signal output unit 132. In this case, the selection signal output unit 132 must output a large number of selection signals to adjust the voltage according to the RC value for each Tx line. In addition, the power supply 135 must also output a large number of step voltages correspondingly. However, in this case, since there are more variables for setting the selection signal and the step voltage, the Tx lines may be configured into M (M is an integer greater than or equal to 2) groups, and the number of the selection signal and the step voltage may be changed corresponding to the M groups. Can be.

In the present invention, an over or underdriving voltage is formed in response to a first embodiment of adjusting the time for forming an over or underdriving voltage in response to the RC delay characteristics of the Tx lines and in response to the RC delay characteristics of the Tx lines. The second embodiment for adjusting the level is described separately. However, the first and second embodiments may be combined and combined.

Hereinafter, a method of driving an electronic device having a touch sensor according to an exemplary embodiment of the present invention will be described, but only a portion related to a driving signal used in the electronic device having the touch sensor will be described.

14 is a view for explaining a method of driving an electronic device having a touch sensor according to an embodiment of the present invention.

First, the edge of the driving signal is detected (S110). Next, it is determined whether the edge of the driving signal is in the rising state or the falling state. (S120) Next, if the edge of the driving signal is the rising state (Y), the driving signal An overdriving voltage is formed at (S130). If an edge of the driving signal is in a polling state (N), an underdriving voltage is formed at the driving signal. (S140) Thereafter, the driving voltage is returned to the reference voltage of the driving signal. S150)

The above driving method has described a part of the process of forming the overdriving voltage and the underdriving voltage in the driving signal. However, in the method of driving an electronic device having a touch sensor according to the present invention, a method for sensing after supplying a driving signal is irrelevant to the gist of the present invention, and thus a detailed description thereof will be omitted.

The present invention provides an electronic device having a touch sensor capable of quickly and uniformly forming a charge / discharge time of touch sensors of a touch screen by improving a difference in charging or discharging time according to RC delay characteristics, and improving touch sensitivity and touch speed. There is an effect of providing a driving method thereof.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical configuration of the present invention described above may be modified in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

50: host system 20: timing controller
12: data driving circuit 14: scan driving circuit
30: touch sensing circuit 40: touch coordinate detection unit
DIS: LCD panel TSP: Touch screen
131: drive signal generator 132: selection signal output unit
133: level shifter 135: power supply
137: power stabilizer 139: voltage selector

Claims (11)

A touch screen comprising touch sensors defined by Tx lines and Rx lines;
A touch sensing circuit configured to supply a driving signal to the Tx lines and sense a voltage change of the touch sensors through the Rx lines; And
And a touch coordinate detector configured to detect a touch input position by comparing the change of the voltage sensed by the touch sensing circuit with a touch threshold value.
The touch sensing circuit includes a charge / discharge circuit unit that forms a high overdriving voltage relative to a charging voltage in a charging section of the driving signal, and forms an underdriving voltage lower than a reference voltage in a discharge section of the driving signal.
The charge / discharge circuit unit may vary the condition under which the overdriving voltage and the underdriving voltage are formed according to the wiring length of the Tx lines.
A drive signal generator for generating a drive signal to be output through the Tx lines;
A power supply unit converting the high potential voltage supplied from the outside into two or more positive voltages and one or more negative voltages and outputting the same;
A selection signal output unit for detecting the driving signal and outputting a selection signal in response to the detected result;
A voltage selector configured to selectively output one of voltages output from the power supply in response to the selection signal;
The selection signal output unit
And detecting the edge of the driving signal and varying the selection signal so that the overdriving voltage and the underdriving voltage are formed separately according to the wiring length of the Tx lines. The method of claim 1,
The charge and discharge circuit portion
And a time period at which the overdriving voltage and the underdriving voltage are formed according to a wiring length of the Tx lines. The method of claim 1,
The charge and discharge circuit portion
And the level at which the overdriving voltage and the underdriving voltage are formed according to a wiring length of the Tx lines. The method of claim 1,
The charge and discharge circuit portion
The longer the wiring length of the Tx lines, the greater the weight of the time or level at which the over-driving voltage and the under-driving voltage is formed, the electronic device having a touch sensor. The method of claim 1,
The charge and discharge circuit portion
Configure the Tx lines in groups of M (M is an integer of 2 or more),
And the time or level at which the overdriving voltage and the underdriving voltage are formed for each of the M groups. The method of claim 1,
The charge and discharge circuit portion
When the edge of the drive signal is a rising state, the overdrive voltage is formed in the drive signal,
And when the edge of the driving signal is in a polling state, forming the underdriving voltage in the driving signal. delete delete The method of claim 1,
The voltage selector
When the selection signal is 01, the overdrive voltage is formed in the driving signal.
When the selection signal is 11, the underdriving voltage is formed on the driving signal.
And if the selection signal is 00, forming the charging voltage in the driving signal. delete The method of claim 1,
The charge and discharge circuit portion
The electronic device having a touch sensor further comprises a power stabilization unit for stabilizing and outputting the voltage output from the power supply unit.

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