KR102520695B1 - Active stylus pen and touch sensing system and driving method of the same - Google Patents

Abstract

The active stylus pen of the present invention includes a first signal processing unit generating a touch frame recognition signal based on a sub-pulse corresponding to a part of each touch screen driving signal received from a touch screen, and the sub pulse in each touch screen driving signal. and a second signal processing unit that generates a pen driving signal to be synchronized with the main pulse except for the pen driving signal, and varies the pen driving signal in units of touch frames according to the touch frame recognition signal so that additional pen information is reflected in the pen driving signal. .

Description

Active stylus pen, touch sensing system including the same, and driving method thereof

The present invention relates to a touch sensing system, and more particularly, to a touch sensing system capable of receiving a touch input through an active stylus pen and a method for driving the same.

A user interface (UI) allows a person (user) to easily control various electronic devices as he/she wants. Representative examples of such a 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, and the like. User interface technology continues to evolve in the direction of enhancing user sensibility and convenience of operation. Recently, user interfaces are evolving into touch UIs, voice recognition UIs, 3D UIs, and the like.

Touch UI is essential for portable information devices. The touch UI is implemented as a method of forming a touch screen on a screen of a display device. Such a touch screen may be implemented in a capacitive manner. A touch screen having a capacitive touch sensor senses a change in capacitance according to the input of a touch screen driving signal, that is, a change in charge of the touch sensor, when a finger or a conductive material contacts (or approaches) the touch sensor. to detect touch input.

The capacitive touch sensor may be implemented as a self capacitance sensor or a mutual capacitance sensor. Each of the electrodes of the self-capacitance sensor may be connected 1:1 to sensor wires formed along one direction. The mutual capacitance sensor may be formed at an intersection of sensor wires orthogonal to each other with a dielectric layer interposed therebetween.

Recently, a stylus pen as well as a finger is widely used as a human interface device (HID) in smart phones and smart books. A stylus pen has the advantage of being able to input more precisely than a finger. There are passive and active types of stylus pens. In the passive type, the capacitance change is small at the point of contact with the touch screen, making it difficult to detect the touch position. Since the active type generates a pen driving signal by itself and outputs it to the point of contact with the touch screen, it is easier to detect the touch position than the passive type.

Recently, active stylus pens are being designed to transmit not only pen driving signals but also various pen additional information such as pen pressure information, button state information, and pen identification (ID) information. However, as disclosed in Korean Publication No. 10-2014-0043299, the conventional active stylus pen required a separate communication block to transmit additional pen information to the touch module, so manufacturing cost increased. . Moreover, since the conventional active stylus pen separately transmits the pen driving signal and pen additional information, transmission load is high. In order to solve this problem, it is possible to consider a method of carrying pen additional information on a pen driving signal and transmitting it in units of touch frames. However, for this, it is necessary to be able to distinguish touch frames from an active stylus pen, but such a method has not yet been developed.

Accordingly, an object of the present invention is an active stylus pen capable of easily distinguishing touch frames in an active stylus pen and reflecting pen additional information in units of one touch frame to a pen driving signal, a touch sensing system including the same, and driving the same to provide a way

Another object of the present invention is to provide an active stylus pen, a touch sensing system including the active stylus pen, and a driving method including the active stylus pen, which can increase the accuracy of synchronization between the active stylus pen and a touch screen.

In order to achieve the above object, the active stylus pen of the present invention is a first signal that generates a touch frame recognition signal for distinguishing a touch frame based on a sub-pulse corresponding to a part of each touch screen driving signal received from a touch screen. A processing unit generates a pen driving signal to be synchronized with a main pulse excluding the sub pulse from each touch screen driving signal, and generates the pen driving signal according to the touch frame recognition signal so that additional pen information is reflected in the pen driving signal. and a second signal processing unit that varies in units of touch frames.

The first signal processor generates a first count value by counting an interval between a first sub-pulse of one touch screen driving signal and a second sub-pulse of another touch screen driving signal adjacent to the one touch screen driving signal, , When the first count value exceeds a preset threshold value, the touch frame recognition signal is generated.

The first signal processor generates a second count value by counting the sub-pulses included in each touch screen driving signal, and generates the touch frame recognition signal when the second count value satisfies a preset value. .

The second signal processor varies the pulse amplitude of the pen driving signal in units of touch frames according to the touch frame recognition signal so that the additional pen information is reflected in the pen driving signal.

The second signal processor varies the pulse duty of the pen driving signal in units of touch frames according to the touch frame recognition signal so that the additional pen information is reflected in the pen driving signal.

The second signal processing unit allocates the pen driving signal to which the pen additional information is reflected, 1 bit per touch frame.

The additional pen information includes pen pressure information indicating pressure when the active stylus pen contacts the touch screen, and button status indicating whether at least one functional button provided in the active stylus pen and performing a specific function is activated. information, and includes pen identification information to distinguish it from other active stylus pens.

In addition, the touch sensing system of the present invention includes a touch screen, a touch driving device that applies a touch screen driving signal to the touch screen and senses a change in capacitance of the touch screen, and generates and transmits a pen driving signal to the touch screen. A first signal for generating a touch frame recognition signal for distinguishing a touch frame based on a sub-pulse corresponding to a part of each touch screen drive signal received from the touch screen. A processing unit generates the pen driving signal to be synchronized with a main pulse excluding the sub pulse from each of the touch screen driving signals, and the pen driving signal is reflected in the pen driving signal according to the touch frame recognition signal so that additional pen information is reflected in the pen driving signal. and a second signal processing unit that varies in units of touch frames.

In addition, the driving method of the touch sensing system according to the present invention includes the steps of bringing an active stylus pen into contact with a touch screen and receiving a touch screen driving signal from the active stylus pen, and synchronizing with the received touch screen driving signal. Generating a pen driving signal from a stylus pen and outputting it to the touch screen, and sensing a change in capacitance of the touch screen according to the touch screen driving signal and the pen driving signal in a touch driving device connected to the touch screen. In the step of generating the pen drive signal from the active stylus pen and outputting the pen drive signal to the touch screen, the touch frame is divided based on a sub pulse corresponding to a part of each touch screen drive signal received from the touch screen. Generating a touch frame recognition signal for performing a touch screen operation, generating the pen drive signal to be synchronized with a main pulse excluding the sub-pulse from each touch screen drive signal, and generating the pen drive signal so that additional pen information is reflected in the pen drive signal. and varying the pen driving signal in units of touch frames according to the frame recognition signal.

The present invention generates a touch frame recognition signal based on a sub-pulse corresponding to a part of each touch screen driving signal received from a touch screen, and determines the pulse amplitude and/or pulse duty of the pen driving signal according to preset pen additional information. Pen additional information can be effectively reflected in the pen driving signal by adjusting the touch frame recognition signal in units of one touch frame. According to the present invention, pen additional information reflected in a pen driving signal can be found by detecting a size change of touch raw data according to a pen driving signal.

The present invention can increase the accuracy of synchronization between an active stylus pen and a touch screen by driving a synchronization signal patterned in a touch screen. In addition, the present invention can implement various additional functions by transmitting a command from the touch screen to the pen using a bit-allocated synchronization signal.

1 is a diagram schematically showing a touch sensing system of the present invention;
2 is a view showing a display device to which a touch sensing system according to an embodiment of the present invention is applied.
3 is a diagram showing an example of a touch sensor embedded in a pixel array;
FIG. 4 is a timing diagram illustrating a method of time-division driving the pixels and touch sensors of the display panel shown in FIG. 3;
5 is a diagram showing an example in which a plurality of touch frames are included in one display frame period;
6 to 8 are views showing a touch driving device according to an embodiment of the present invention.
9 is a diagram showing multiplexers and sensing units connected to touch sensor blocks;
10 is a view showing the internal configuration of an active stylus pen according to the present invention.
11 is a view showing an operation sequence of reflecting pen additional information to a pen driving signal in an active stylus pen according to the present invention.
12A and 12B are diagrams illustrating a method of distinguishing a touch frame in an active stylus pen and various modulation forms of a pen driving signal for expressing pen additional information.
13A and 13B are diagrams showing another method for distinguishing touch frames in an active stylus pen and various modulation forms of a pen driving signal for expressing pen additional information.
14 is a diagram showing a method of generating pen additional information by utilizing a plurality of touch frames in an active stylus pen.
15 is a diagram showing changes in touch raw data sensed by a touch driving device according to pen additional information;
16 and 17 are diagrams showing a method for increasing the accuracy of synchronization between an active stylus pen and a touch screen.
18 is a diagram showing an example of bit allocation according to a synchronization signal pattern;

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Like reference numbers throughout the specification indicate substantially the same elements. In the following description, if it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

[touch sensing system]

1 schematically shows the touch sensing system of the present invention.

Referring to FIG. 1 , the touch sensing system of the present invention includes a display device 10 and an active stylus pen 20 .

The display device 10 performs a display function and a touch detection function. The display device 10 is capable of detecting a touch by a contact of a conductive object such as a finger or an active stylus 20, and has an integral capacitive touch screen therein. Here, the touch screen may be configured in a form independent of a display panel for display implementation, or may be embedded in a pixel array of the display panel. A detailed configuration and operation of the display device 10 will be described later with reference to FIGS. 2 to 9 .

The active stylus pen 20 facilitates detection of a touch position on a touch screen by generating a pen drive signal based on a touch screen drive signal received from the touch screen and outputting the pen drive signal to a contact point with the touch screen. The active stylus pen 20 generates a touch frame recognition signal based on a sub-pulse corresponding to a part of each touch screen drive signal, and drives the pen according to the touch frame recognition signal so that preset pen additional information is reflected in the pen drive signal. The signal is varied in units of touch frames. The touch sensing system detects the touch input position and touch additional information by the active stylus pen 20 by analyzing changes in touch raw data according to the pen driving signal. The pen additional information includes pen pressure information indicating pressure when the active stylus pen contacts the touch screen, button state information indicating whether at least one functional button provided in the active stylus pen and performing a specific function is activated, and other information. It may include pen identification information for distinguishing it from an active stylus pen.

The configuration and operation of the active stylus pen 20 will be described later with reference to FIGS. 10 to 15 .

[Display device]

2 shows a display device 10 to which a touch sensing system according to an embodiment of the present invention is applied. 3 shows an example of a touch sensor embedded in a pixel array. FIG. 4 shows a method of time-division driving the pixels and touch sensors of the display panel shown in FIG. 3 . 5 shows an example in which a plurality of touch frames are included in one display frame period. 6 to 8 show a touch driving device according to an embodiment of the present invention. 9 shows multiplexers and sensing units connected to touch sensor blocks.

2 to 9, the display device 10 of the present invention includes a liquid crystal display (LCD), a field emission display (FED), and a plasma display panel (PDP). ), an organic light emitting display (OLED), and an electrophoresis display (EPD). In the following embodiments, it is described that the display device is implemented as a liquid crystal display device, but the display device of the present invention is not limited to the liquid crystal display device.

The display device 10 includes a display module and a touch module.

The touch module includes a touch screen (TSP) and a touch driving device 18 .

The touch screen TSP may be implemented in a capacitive manner that senses a touch input through a plurality of capacitive sensors. The touch screen TSP includes a plurality of touch sensors having capacitance. Capacitance can be divided into self capacitance and mutual capacitance. Self-capacitance may be formed along a single-layer conductor line formed in one direction, and mutual capacitance may be formed between two orthogonal conductor lines.

Touch sensors of the touch screen TSP may be embedded in a pixel array of the display panel DIS. An example in which the touch screen TSP is embedded in the pixel array of the display panel DIS is shown in FIG. 3 . Referring to FIG. 3 , the pixel array of the display panel DIS includes touch sensors C1 to C4 and sensor lines L1 to Li, where i is smaller than m and n and connected to the touch sensors C1 to C4. positive integers). The common electrode COM of the pixels 101 is divided into a plurality of segments. The touch sensors C1 to C4 are implemented with divided common electrodes COM. One common electrode segment is commonly connected to a plurality of pixels 101 and forms one touch sensor. Therefore, as shown in FIG. 4 , the touch sensors C1 to C4 supply the common voltage Vcom to the pixels 101 during the display periods Td1 and Td2 and touch screen drive signals during the touch periods Tt1 and Tt2. (Ts) is received and touch input is sensed. 3 shows a self-capacitance type touch sensor, the touch sensors C1 to C4 are not limited thereto.

The touch driving device 18 applies the touch screen driving signal Ts to the touch sensors C1 to C4 and senses the amount of change in charge of the touch sensors C1 to C4, such as a finger (or stylus pen). It determines whether the conductive material is touched and its location.

The touch driving device 18 drives the touch sensors during the touch periods Tt1 and Tt2 in response to the touch enable signal TEN input from the timing controller 16 or the host system 19 . The touch driving device 18 senses a touch input by supplying the touch screen driving signal Ts to the touch sensors C1 to C4 through the sensor lines L1 to Li during the touch periods Tt1 and Tt2. The touch driving device 18 determines touch input by analyzing the change in charge of the touch sensor, which varies depending on whether or not there is a touch input, and calculates the coordinates of the touch input position. Coordinate information of the touch input position is transmitted to the host system.

The touch driving device 18 drives the touch sensors C1 to C4 in response to the touch enable signal TEN during the touch periods Tt1 and Tt2, and displays an input image during one display frame period as shown in FIG. 5 . By allocating at least two or more touch frames TF1, TF2, and TF3 for driving the touch sensors C1 to C4 within the screen, the touch report rate can be higher than the display frame rate. Here, a plurality of touch periods corresponding to the number of multiplexers may be included in one touch frame.

For example, if the display period (Td1, Td2) and the touch period (Tt1, Tt2) are divided into a plurality of periods as shown in FIG. , Tt2), the touch input is sensed, and coordinate information of the touch input is transmitted to the host system when each touch frame is completed. Accordingly, the present invention can increase the touch report rate more than the display frame rate. The display frame rate is the frame frequency at which one frame image is written to the pixel array. The touch reporter rate is the rate at which coordinate information of a touch input is generated. The higher the touch reporter rate, the faster the coordinate recognition speed of the touch input, so the touch sensitivity improves.

The touch driving device 18 of the present invention may be implemented as an integrated circuit (IC) package as shown in FIGS. 6 to 8 .

Referring to FIG. 6 , the touch driving device 18 includes a driver IC (DIC) and a touch IC (TIC).

The driver IC (DIC) includes a touch sensor channel unit 100, a Vcom buffer 110, a switch array 120, a timing control signal generator 130, a multiplexer (MUX) 140, and a DTX compensator ( 150).

The touch sensor channel unit 100 is connected to the electrodes of the touch sensors through sensor lines and connected to the Vcom buffer 110 and the multiplexer 140 through the switch array 120 . A multiplexer 140 connects the sensor lines to a touch IC (TIC). In the case of the 1:3 multiplexer, the multiplexer 140 reduces the number of channels of the touch IC (TIC) by sequentially connecting one channel of the touch IC (TIC) to three sensor lines in a time division manner. The multiplexer 140 sequentially selects sensor lines to be connected to channels of the touch IC (TIC) in response to MUX control signals (MUX C1 to C3). The multiplexer 140 is connected to channels of the touch IC (TIC) through touch lines.

The Vcom buffer 110 outputs a common voltage Vcom of pixels. The switch array 120 supplies the common voltage Vcom from the Vcom buffer 110 to the touch sensor channel unit 100 during the display period under the control of the timing control signal generator 130 . The switch array 120 connects the sensor lines to the touch IC (TIC) during the touch period under the control of the timing control signal generator 130 .

The timing control signal generation unit 130 generates timing control signals for controlling operation timings of a display driving circuit and a touch IC (TIC).

The timing control signal generator 130 may be included in the timing controller 16 shown in FIG. 2 . The timing control signal generator 130 drives the display driving circuit during the display period and drives the touch IC (TIC) during the touch period.

As shown in FIG. 4 , the timing control signal generation unit 130 generates the touch enable signal TEN defining the display period Td1 and Td2 and the touch period Tt1 and Tt2 to form a display driving circuit and a touch IC (TIC). synchronize The display driving circuit writes image data to pixels during the first level period of the touch enable signal TEN. The touch IC (TIC) senses a touch input by driving touch sensors in response to the second level of the touch enable signal (TEN). The first level of the touch enable signal TEN may be a high level, and the second level may be a low level, but may be set to the opposite.

The touch IC (TIC) is connected to a driving power supply unit (not shown) to receive driving power. The touch IC (TIC) generates the touch screen driving signal Ts in response to the second level of the touch enable signal TEN and applies it to the touch sensors. The touch screen driving signal Ts may be generated in various forms such as a square wave type pulse, sine wave, triangular wave, etc., but is preferably implemented as a square wave. The touch screen driving signal Ts may be applied N times to each of the touch sensors so that charges may be accumulated N times or more (where N is a natural number greater than or equal to 2) in the integrator of the touch IC TIC.

Noise may increase in a touch sensor signal according to a change in input image data. The DTX compensator 150 analyzes the input image data, removes noise components from the touch raw data according to the gray level change of the input image, and transmits the noise component to the touch IC (TIC). DTX stands for Display and Touch crosstalk. Content related to the DTX compensator 150 is described in detail in Patent Application No. 10-2012-0149028 (application filed on December 19, 2012) filed by the present applicant. In the case of a system in which the noise of the touch sensor does not change sensitively according to the data change of the input image, the DTX compensator 150 is unnecessary and can be omitted. In FIG. 6, DTX DATA is output data of the DTX compensator 150.

The touch IC (TIC) drives the multiplexer 140 during the touch intervals Tt1 and Tt2 in response to the touch enable signal TEN from the timing control signal generator 130 to pass through the multiplexer 140 and the sensor lines. Receives the charge of the touch sensor. In FIG. 6, MUXs C1 to C3 are signals for selecting channels of a multiplexer.

The touch IC (TIC) detects the amount of change in charge before and after the touch input from the touch sensor signal, compares the amount of change in charge with a predetermined threshold value, and determines the locations of touch sensors having a change in charge equal to or greater than the threshold value as the touch input area. The touch IC (TIC) calculates coordinates for each touch input and transmits touch data (TDATA(XY)) including touch input coordinate information to the external host system 19 . A touch IC (TIC) includes an amplifier that amplifies the charge of the touch sensor, an integrator that accumulates the charge received from the touch sensor, an analog to digital converter (ADC) that converts the voltage of the integrator into digital data, and an operation logic unit. The operation logic unit compares the touch raw data output from the ADC with a threshold value, determines a touch input according to the comparison result, and executes a touch recognition algorithm that calculates coordinates.

A driver IC (DIC) and a touch IC (TIC) may transmit and receive signals through a Serial Peripheral Interface (SPI) interface.

The host system 19 means a system body of an electronic device to which the display device 10 of the present invention is applicable. The host system 19 may be any one of a phone system, a television (TV) system, a set-top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), and a home theater system. The host system 19 transmits input image data (RGB) to the driver IC (DIC), receives touch input data (TDATA(XY)) from the touch IC (TIC), and generates an application associated with the touch input. run

Referring to FIG. 7 , the touch driving device 18 includes a driver IC (DIC) and a Micro Controller Unit (MCU).

The driver IC (DIC) includes a touch sensor channel unit 100, a Vcom buffer 110, a switch array 120, a first timing control signal generator 130, a multiplexer 140, a DTX compensator 150, a sensing It includes a unit 160, a second timing control signal generator 170 and a memory 180. This embodiment differs from the above-described embodiment of FIG. 6 in that the sensing unit 160 and the second timing control generating unit 170 are integrated into a driver IC (DIC). The first timing control generator 130 is substantially the same as that of FIG. 6 . Accordingly, the first timing control generator 130 generates timing control signals for controlling operation timings of the display driving circuit and the touch IC (TIC).

The multiplexer 140 floats the touch sensor electrodes accessed by the sensing unit 160 under the control of the MCU. The sensing unit 160 accesses touch sensor electrodes other than touch sensor electrodes connected to pixels that charge the data voltage. The multiplexer 140 may supply a common voltage Vcom under the control of an MCU. When the resolution of the touch screen is M×N as shown in FIG. 9 (M and N are each a positive integer greater than or equal to 2), the number of multiplexers 140 required is M. When the resolution of the touch screen is M×N, the touch sensor electrodes 22 are divided into M×N numbers. Each multiplexer 140 is connected to N touch sensor electrodes 22 through N sensor lines 115, and sequentially connects N sensor lines 115 to one sensing unit 160. .

The sensing unit 160 is connected to the sensor lines 115 through the multiplexer 140 to measure changes in voltage waveforms received from the touch sensor electrodes 22 and converts them into digital data. The sensing unit 160 includes an amplifier that amplifies the received voltage of the touch sensor electrodes 22, an integrator that accumulates the voltage of the amplifier, and an analog-to-digital converter that converts the voltage of the integrator into digital data. , hereinafter referred to as "ADC"). The digital data output from the ADC is transmitted to the MCU as touch raw data. When the resolution of the touch screen is M×N as shown in FIG. 9 (M and N are each positive integers greater than or equal to 2), M sensing units 160 are required.

The second timing control generating unit 170 generates timing control signals, clocks, and the like for controlling operation timings of the multiplexer 140 and the sensing unit 160 . The DTX compensator 150 in the driver IC (DIC) may be omitted. The memory 180 temporarily stores the touch raw data TDATA under the control of the second timing control generator 170 .

A driver IC (DIC) and an MCU can transmit and receive signals through a Serial Peripheral Interface (SPI) interface. The MCU compares the touch raw data (TDATA) with a threshold value, determines a touch input according to the comparison result, and executes a touch recognition algorithm that calculates coordinates.

Referring to FIG. 8 , the touch driving device 18 includes a driver IC (DIC) and a memory (Memory, MEM).

The driver IC (DIC) includes a touch sensor channel unit 100, a Vcom buffer 110, a switch array 120, a first timing control signal generator 130, a multiplexer 140, a DTX compensator 150, a sensing It includes a unit 160, a second timing control signal generator 170, a memory 180, and an MCU 190. This embodiment differs from the above-described embodiment of FIG. 6 in that the MCU 190 is integrated into a driver IC (DIC). The MCU 18 compares the touch raw data TDATA with a threshold value, determines a touch input according to the comparison result, and executes a touch recognition algorithm that calculates coordinates.

The memory MEM stores register setting values related to timing information necessary for the operation of the display driving circuit and the sensing unit 160 . The register setting values are loaded from the memory MEM into the first timing control signal generator 16 and the second timing control signal generator 170 when the power of the display device is turned on. The first timing control signal generation unit 16 and the second timing control signal generation unit 170 generate timing control signals for controlling the display driving circuit and the sensing unit 160 based on the register setting values read from the memory. do. It is possible to respond to model change by changing register setting values of the memory MEM without structural change of the driving device.

The display module may include a display panel (DIS), display driving circuits 12, 14, and 16, and a host system 19.

The display panel DIS includes a liquid crystal layer formed between two sheets of substrates. The pixel array of the display panel DIS includes pixels formed in a pixel area 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). . Each of the pixels is connected to TFTs (Thin Film Transistors) formed at the intersections of the data lines D1 to Dm and the gate lines G1 to Gn, a pixel electrode that charges the data voltage, and a pixel electrode to form a liquid crystal cell. A storage capacitor (Cst) for maintaining a voltage may be included.

A black matrix, a color filter, and the like may be formed on the upper substrate of the display panel DIS. A lower substrate of the display panel DIS may be implemented as a color filter on TFT (COT) structure. In this case, the black matrix and color filters may be formed on the lower substrate of the display panel DIS. The common electrode to which the common voltage is supplied may be formed on an upper substrate or a lower substrate of the display panel DIS. A polarizing plate is attached to each of the upper and lower substrates of the display panel DIS, and an alignment layer for setting a pretilt angle of the liquid crystal is formed on an inner surface in contact with the liquid crystal. A column spacer for maintaining a cell gap of the liquid crystal cell is formed between the upper substrate and the lower substrate of the display panel DIS.

A backlight unit may be disposed under the rear surface of the display panel DIS. The backlight unit is implemented as an edge type or direct type backlight unit and irradiates light to the display panel DIS. The 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 display driving circuit includes a data driving circuit 12, a gate driving circuit 14, and a timing controller 16 to write video data of an input image to pixels of the display panel DIS. The data driving circuit 12 converts the digital video data (RGB) input from the timing controller 16 into an analog positive/negative polarity gamma compensation voltage and outputs a data voltage. The data voltage output from the data driving circuit 12 is supplied to the data lines D1 to Dm. The gate driving circuit 14 sequentially supplies a gate pulse (or scan pulse) synchronized with the data voltage to the gate lines G1 to Gn to select a pixel line of the display panel DIS to which the data voltage is written. The gate driving circuit 14 may be disposed together with the pixels on the substrate of the display panel DIS.

The timing controller 16 inputs 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) input from the host system 19. and the operation timings of the data driving circuit 12 and the gate driving circuit 14 are synchronized. 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, POL), a source output enable signal (Source Output Enable, SOE), and the like.

The host system 19 transmits timing signals (Vsync, Hsync, DE, MCLK) together with digital video data (RGB) to the timing controller 16, and touch coordinate information (XY) input from the touch driver 18. ) and associated applications can be executed.

Meanwhile, the touch enable signal TEN of FIG. 4 may be generated by the host system 19 . During the display period Td1 and Td2, the data driving circuit 12 supplies data voltages to the data lines D1 to Dm under the control of the timing controller 16, and the gate driving circuit 14 controls the timing controller 16. ), gate pulses synchronized with the data voltage are sequentially supplied to the gate lines G1 to Gn. Meanwhile, during the display periods Td1 and Td2, the touch driving device 18 stops operating.

During the touch periods Tt1 and Tt2, the touch driving device 18 applies the touch screen driving signal Ts to the touch sensors of the touch screen TSP. Meanwhile, during the touch periods Tt1 and Tt2, the display driving circuits 12, 14, and 16 minimize parasitic capacitance between the signal lines D1 to Dm and G1 to Gn connected to the pixels and the touch sensors. AC signals of the same amplitude and phase as the touch screen driving signal Ts may be supplied to the signal lines D1 to Dm and G1 to Gn. In this case, the display noise mixed with the touch sensing signal is drastically reduced and the accuracy of the touch sensing is increased.

[ stylus pen]

10 shows the internal configuration of the active stylus pen 20 according to the present invention.

Referring to FIG. 10, the active stylus pen 20 includes a housing 280, a conductive tip 210 protruding outside one side of the housing 280, and a conductive tip 210 connected to the inside of the housing 280. A switching unit 220, a receiving unit 230 that receives a touch screen driving signal input from the conductive tip 210 through the switching unit 220, and a pen unit based on the touch screen driving signal from the receiving unit 230 The signal processing unit 250 generates a digital pen driving signal reflecting the information, and after level-shifting the digital pen driving signal generated by the signal processing unit 250 to an analog level, the conductive tip 210 passes through the switching unit 220. It includes a driving unit 240 that supplies, a power supply unit 260 that generates driving power required for operation, and an input/output interface 270.

The conductive tip 210 is made of a conductive material such as metal and serves as a receiving electrode and a transmitting electrode. When the conductive tip 210 contacts the touch screen TSP of the display device 10, the conductive tip 210 is coupled with the touch screen TSP at the contact point. The conductive tip 210 receives a touch screen drive signal from the touch screen TSP at the contact point, and then transfers the pen drive signal generated inside the active stylus pen 20 to the touch screen TSP to be synchronized with the touch screen drive signal. send to branch

The switching unit 220 electrically connects the conductive tip 210 and the receiver 230 for the Rx time when the conductive tip 210 is in contact with the touch screen TSP of the display device 10. Then, by electrically connecting the conductive tip 210 and the driver 240 during the Tx time period, the reception timing of the touch screen driving signal and the transmission timing of the pen driving signal are temporally separated. Since the conductive tip 210 serves as both a receiving electrode and a transmitting electrode, the structure of the active stylus pen 20 is simplified.

The receiving unit 230 may include at least one amplifier to amplify the touch screen driving signal input from the conductive tip 210 through the switching unit 220 . The receiving unit 230 includes a comparator and compares the amplified signal with a preset reference voltage, and outputs the result to the signal processing unit 250 .

The signal processing unit 250 classifies touch frames based on the touch screen driving signal input from the receiving unit 230 and changes the pen driving signal in units of touch frames to reflect additional pen information to the pen driving signal. To this end, the signal processing unit 250 includes a first signal processing unit for distinguishing touch frames and a second signal processing unit for reflecting pen additional information to the pen driving signal.

The first signal processor may generate a touch frame recognition signal based on a sub-pulse corresponding to a part of each touch screen driving signal received from the touch screen. The second signal processing unit generates a pen driving signal to be synchronized with the main pulse excluding sub pulses from each touch screen driving signal, and transmits the pen driving signal in units of touch frames according to the touch frame recognition signal so that additional pen information is reflected in the pen driving signal. can be changed to

The signal processing unit 250 outputs a pen driving signal reflecting pen additional information to the driving unit.

The driving unit 240 includes a level shifter to shift the digital level pen driving signal to an analog level. The driving unit 240 outputs the level-shifted pen driving signal to the conductive tip 210 through the switching unit 220 .

The input/output interface 270 is connected to the power supply 260 and can supply power necessary for the receiver 230 , the driver 240 and the signal processor 250 .

11 shows an operation sequence of reflecting pen additional information to a pen driving signal in the active stylus pen 20 according to the present invention.

Referring to FIG. 11 , in a state in which power is applied through the input/output interface 270 and the power supply 260, the conductive tip 210 contacts a predetermined point of the touch screen TSP (S1, S2).

During the touch period, a touch screen drive signal is supplied to each touch sensor of the touch screen TSP. During the touch period, the conductive tip 210 is coupled to the touch screen TSP at the contact point, senses a touch screen drive signal received from the touch screen TSP, and transfers the sensed signal to the receiver 220. . The receiving unit 220 amplifies the touch screen driving signal through an internal amplifier, compares the amplified signal with a reference voltage in an internal comparator, and outputs the result to the signal processing unit 250 (S3).

The signal processing unit 250 analyzes the touch screen driving signal input from the receiving unit 230 to determine a timing synchronized with the touch screen driving signal, and generates a pen driving signal according to the synchronization timing. In particular, the signal processing unit 250 generates a touch frame recognition signal based on the touch screen drive signal to classify the touch frame, and the pulse amplitude and/or pulse of the pen drive signal in units of touch frames corresponding to preset pen additional information. By varying the duty, a pen driving signal reflecting pen additional information is output (S4, S5, S6).

12A and 12B show a method of distinguishing a touch frame in an active stylus pen and various modulation types of a pen driving signal for expressing pen additional information. 13A and 13B show another method of distinguishing touch frames in an active stylus pen and various modulation types of pen driving signals for expressing pen additional information. 14 shows a method of generating pen additional information by utilizing a plurality of touch frames in an active stylus pen. And, FIG. 15 shows a change in touch raw data sensed by the touch driving device according to pen additional information.

12A and 12B, the first signal processing unit of the active stylus pen 20 receives a first sub-pulse of one touch screen driving signal Ts and another touch adjacent to the one touch screen driving signal Ts. A first count value is generated by counting an interval between second sub-pulses of the screen drive signal Ts, and a touch frame recognition signal TFsync for distinguishing touch frames is generated when the first count value exceeds a preset threshold. can create In FIGS. 12A and 12B, Mux 1 to Mux last are touch screen driving signals corresponding to one touch period (Tt1 or Tt2) shown in FIG. 4, respectively.

The touch screen driving signal Ts includes a sub pulse allocated to a part of the 1-touch period and a main pulse allocated to the rest of the 1-touch period. A sub-pulse of the touch screen driving signal Ts may be used to determine the validity of the touch screen driving signal Ts. The first signal processing unit of the active stylus pen 20 may generate the touch frame recognition signal TFsync based on the sub-pulse of the touch screen driving signal Ts.

For example, the first signal processor measures intervals between neighboring touch screen driving signals (Mux 1 and Mux 2, Mux 2 and Mux 3, ..., Mux Last-1 and Mux Last, Mux Last and Mux 1) A first count value corresponding to (D or D+d) is generated, and a touch frame recognition signal TFsync is generated when the first count value exceeds a preset threshold. When the vertical blank period d is further included between the touch frames TFn-1 and TFn, the interval (D+) between the touch screen driving signals (Mux Last and Mux 1) adjacent to each other in different touch frames d) may be larger by the vertical blank period (d) than the distance (D) between adjacent touch screen driving signals (Mux Last-1 and Mux Last) within the same touch frame. In this case, the first signal processor determines that the touch screen driving signal (Mux 1) subsequent to the touch screen driving signal (Mux Last) belongs to the new touch frame, and determines that the touch screen driving signal (Mux 1) of the new touch frame belongs to the touch screen driving signal (Mux 1). A frame recognition signal TFsync may be generated.

12A and 12B, the second signal processing unit of the active stylus pen 20 generates a pen driving signal Ps to be synchronized with the main pulse excluding sub pulses from each touch screen driving signal Ts. At this time, the second signal processing unit of the active stylus pen 20 pulses the pen driving signal Ps according to the touch frame recognition signal TFsync so that additional pen information previously set is reflected in the pen driving signal Ps as shown in FIG. 12A. The pen driving signal Ps according to the touch frame recognition signal TFsync so that the duty is variable in units of touch frames TFn-1 or TFn, or the additional pen information preset in advance is reflected in the pen driving signal Ps as shown in FIG. 12B. ) may be varied in units of touch frames (TFn-1, TFn). Meanwhile, although not shown in the drawing, the second signal processing unit of the active stylus pen 20 responds to the pen driving signal Ps according to the touch frame recognition signal TFsync so that additional pen information previously set is reflected in the pen driving signal Ps. ) may be varied in units of touch frames (TFn-1, TFn).

13A and 13B, the first signal processor of the active stylus pen 20 counts the sub-pulses included in each touch screen driving signal Ts to generate a second count value, and the second count value When this preset value is satisfied, a touch frame recognition signal TFsync for distinguishing touch frames may be generated. In FIGS. 13A and 13B, Mux 1 to Mux last are touch screen driving signals corresponding to one touch period (Tt1 or Tt2) shown in FIG. 4, respectively. For example, when the 2 count value corresponding to the number of sub-pulses (#1 to #Last) included in each touch screen driving signal Ts meets a preset value, the first signal processing unit touches for distinguishing touch frames. A frame recognition signal TFsync may be generated.

Referring to FIGS. 13A and 13B , the second signal processor of the active stylus pen 20 generates the pen driving signal Ps to be synchronized with the main pulse excluding sub pulses from each touch screen driving signal Ts. At this time, the second signal processing unit of the active stylus pen 20 pulses the pen driving signal Ps according to the touch frame recognition signal TFsync so that additional pen information previously set is reflected in the pen driving signal Ps as shown in FIG. 13A. The pen drive signal Ps according to the touch frame recognition signal TFsync so that the duty is variable in units of touch frames TFn-1 or TFn, or the additional pen information set in advance is reflected in the pen drive signal Ps as shown in FIG. 13B. ) may be varied in units of touch frames (TFn-1, TFn). Meanwhile, although not shown in the drawing, the second signal processing unit of the active stylus pen 20 responds to the pen driving signal Ps according to the touch frame recognition signal TFsync so that additional pen information previously set is reflected in the pen driving signal Ps. ) may be varied in units of touch frames (TFn-1, TFn).

Meanwhile, touch input detection should not be hindered due to the variation of the pen driving signal Ps. Therefore, the range in which the second signal processing unit can vary the pulse amplitude and/or pulse duty of the pen driving signal Ps to indicate pen additional information must be made within a range in which the pen driving signal Ps can detect the touch input. You should pay attention to the

On the other hand, the second signal processing unit generates a pen driving signal Ps in which additional pen information is reflected in the same manner as in FIGS. " can be expressed as That is, the second signal processor may generate the pen driving signal Ps to have a first pulse amplitude and/or a first pulse duty in order to express the pen driving signal Ps as “1”, and the pen driving signal ( In order to express Ps) as “0”, the pen driving signal Ps may be generated to have a second pulse amplitude (less than the first pulse amplitude) and/or a second pulse duty (less than the first pulse duty). .

The second signal processing unit allocates the pen driving signal Ps, in which the additional information of the pen is reflected, by 1 bit to each touch frame, and implemented through a plurality of touch frames, so that sophisticated information can be expressed. For example, as shown in FIG. 14 , the second signal processing unit assigns 1 bit to each of the 8 touch frames TF1 to TF8 for the pen driving signal Ps reflecting pen additional information, so that 256 steps can be expressed.

As shown in FIG. 15 , the touch sensing value (touch raw data) according to the pen driving signal Ps represented by the logical value “1” is greater than the touch sensing value according to the pen driving signal Ps represented by the logical value “0” . The touch driving device 18 of the display device 10 may detect additional bits of pen information based on the size of the touch sensing value according to the pen driving signal Ps.

16 and 17 show a method for increasing the accuracy of synchronization between an active stylus pen and a touch screen. And, Figure 18 shows an example of bit allocation according to the pattern of the synchronization signal.

The active stylus pen operates by driving a signal synchronized with the touch screen. Therefore, there is a need for a method for accurately synchronizing active stylus pens even in environments with various noises. In addition, a function of changing the operating frequency of the active stylus pen to avoid performance degradation due to noise and other additional functions should be implemented.

16 and 17, the touch screen driving signal Ts of the present invention is a beacon including a pen operation mode, hovering or contact status, and tilt data transmission status. contains more signals. The beacon signal corresponds to the dummy touch period (Dummy TP). The active stylus pen may generate a touch frame recognition signal TFsync based on a beacon signal and distinguish touch frames according to the touch frame recognition signal TFsync.

The sub pulse of the touch screen drive signal Ts and the beacon signal are synchronization signals for synchronization between the main pulse of the touch screen drive signal Ts and the pen drive signal Ps. The touch driving device drives a beacon signal in the dummy touch period (Dummy TP) and drives a patterned ping signal in each touch period (TP) so that accurate synchronization is possible even in the presence of noise. The synchronization signal can be implemented as a patterned Direct Sequence Spread Spectrum (DSSS) code for maximum noise immunity. If the synchronization signal is implemented as a DSSS code, the signal-to-noise ratio (SNR) is improved because the frequency bandwidth of the transmitted signal can be distributed and transmitted. That is, if the synchronization signal is implemented as a DSSS code, it can be driven even in a noisy environment to increase the accuracy of synchronization between the active stylus pen and the touch screen.

The touch drive device transmits a command from the touch screen to the active stylus pen and allocates a plurality of bits according to the pattern of the synchronization signal to transmit various additional functions. That is, the touch drive device can transmit various additional functions such as changing the driving frequency of the pen and changing operating parameters to the pen by driving the bit-allocated beacon signal as shown in FIG. 18 in the dummy touch period (Dummy TP). In addition, the touch driving device can increase the accuracy of synchronization between the active stylus pen and the touch screen by driving a bit-allocated ping signal as shown in FIG. 18 in each touch period (TP). As described above, the present invention generates a touch frame recognition signal based on a sub-pulse corresponding to a part of each touch screen driving signal received from the touch screen, and sets the pulse amplitude and/or pulse duty of the pen driving signal according to preset pen additional information to the touch frame Pen additional information can be effectively reflected in the pen driving signal by adjusting the touch frame unit according to the recognition signal. According to the present invention, pen additional information reflected in a pen driving signal can be found by detecting a size change of touch raw data according to a pen driving signal.

Furthermore, the present invention can increase the accuracy of synchronization between an active stylus pen and a touch screen by using a patterned synchronization signal. In addition, the present invention can implement various additional functions by transmitting a command from the touch screen to the pen using a bit-allocated synchronization signal.

Through the above description, those skilled in the art will understand that various changes and modifications are possible without departing from the spirit of the present 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 determined by the claims.

10: display device 18: touch drive device
20: stylus pen 210: conductive tip
220: switching unit 230: receiving unit
240: driving unit 250: signal processing unit

Claims (33)

a first signal processor generating a touch frame recognition signal for distinguishing a touch frame based on a sub-pulse corresponding to a part of each touch screen driving signal received from the touch screen; and
A pen driving signal is generated to be synchronized with a main pulse excluding the sub pulse from each touch screen driving signal, and the pen driving signal is transmitted in units of touch frames according to the touch frame recognition signal so that pen additional information is reflected in the pen driving signal. Including a second signal processing unit variable to ,
In the touch screen driving signal, the sub-pulse is allocated to a part of a 1-touch period, and the main pulse is allocated to a remaining period of the 1-touch period;
The touch screen drive signal further includes a beacon signal driven in a dummy touch period different from the first touch period,
The sub-pulse and the beacon signal are synchronization signals for synchronizing the main pulse and the pen driving signal, and each is implemented as a patterned ping signal. According to claim 1,
The first signal processing unit,
A first count value is generated by counting an interval between a first sub-pulse of one touch screen driving signal and a second sub-pulse of another touch screen driving signal adjacent to the one touch screen driving signal, and the first count value is An active stylus pen that generates the touch frame recognition signal when a preset threshold value is exceeded. According to claim 1,
The first signal processing unit,
An active stylus pen that counts the sub-pulses included in each touch screen driving signal to generate a second count value, and generates the touch frame recognition signal when the second count value satisfies a preset value. According to claim 1,
The second signal processing unit,
An active stylus pen that varies a pulse amplitude of the pen driving signal in units of touch frames according to the touch frame recognition signal so that the pen additional information is reflected in the pen driving signal. According to claim 1,
The second signal processing unit,
An active stylus pen that varies a pulse duty of the pen driving signal in units of touch frames according to the touch frame recognition signal so that the pen additional information is reflected in the pen driving signal. According to any one of claims 1 to 5,
The second signal processing unit,
An active stylus pen that allocates a pen driving signal reflecting the pen additional information by 1 bit to 1 touch frame. According to claim 1,
The additional pen information includes pen pressure information indicating pressure when the active stylus pen contacts the touch screen, and button status indicating whether at least one functional button provided in the active stylus pen and performing a specific function is activated. information, an active stylus pen containing pen identification information to distinguish it from other active stylus pens. According to claim 1,
The beacon signal is an active stylus pen including a pen operation mode, whether it is hovering or contacting, and whether or not tilt data is transmitted. delete According to claim 1,
The synchronization signal is an active stylus pen implemented as a patterned Direct Sequence Spread Spectrum (DSSS) code. According to claim 1,
An active stylus pen in which a plurality of bits are allocated according to a pattern of the synchronization signal so that various additional functions can be secured by transmitting a command from the touch screen to the active stylus pen. a touch screen,
A touch driving device for applying a touch screen driving signal to the touch screen and sensing a change in capacitance of the touch screen;
An active stylus pen for generating and transmitting a pen drive signal to the touch screen;
The active stylus pen,
a first signal processor generating a touch frame recognition signal for distinguishing a touch frame based on a sub-pulse corresponding to a part of each touch screen driving signal received from the touch screen; and
The pen driving signal is generated to be synchronized with a main pulse excluding the sub pulse from each touch screen driving signal, and the pen driving signal is converted to a touch frame according to the touch frame recognition signal so that additional pen information is reflected in the pen driving signal. Including a second signal processing unit variable in units,
In the touch screen driving signal, the sub-pulse is allocated to a part of a 1-touch period, and the main pulse is allocated to a remaining period of the 1-touch period;
The touch screen drive signal further includes a beacon signal driven in a dummy touch period different from the first touch period,
The sub-pulse and the beacon signal are synchronization signals for synchronizing the main pulse and the pen driving signal, and each is implemented as a patterned ping signal. According to claim 12,
The first signal processing unit,
A first count value is generated by counting an interval between a first sub-pulse of one touch screen driving signal and a second sub-pulse of another touch screen driving signal adjacent to the one touch screen driving signal, and the first count value is A touch sensing system for generating the touch frame recognition signal when a preset threshold value is exceeded. According to claim 12,
The first signal processing unit,
The touch sensing system generates a second count value by counting the sub-pulses included in each touch screen driving signal, and generates the touch frame recognition signal when the second count value satisfies a preset value. According to claim 12,
The second signal processing unit,
A touch sensing system for varying the pulse amplitude of the pen driving signal in units of touch frames according to the touch frame recognition signal so that the pen additional information is reflected in the pen driving signal. According to claim 12,
The second signal processing unit,
and varying a pulse duty of the pen driving signal in units of touch frames according to the touch frame recognition signal so that the pen additional information is reflected in the pen driving signal. According to any one of claims 12 to 16,
The second signal processing unit,
A touch sensing system for allocating a pen driving signal reflecting the pen additional information by 1 bit to 1 touch frame. According to claim 12,
The additional pen information includes pen pressure information indicating pressure when the active stylus pen contacts the touch screen, and button status indicating whether at least one functional button provided in the active stylus pen and performing a specific function is activated. Information, a touch sensing system that includes pen identification information to distinguish it from other active stylus pens. According to claim 12,
The beacon signal includes a pen operation mode, whether or not it is hovering or contact, and whether or not tilt data is transmitted. delete According to claim 12,
The synchronization signal is a touch sensing system implemented as a patterned Direct Sequence Spread Spectrum (DSSS) code. According to claim 12,
A touch sensing system in which a plurality of bits are allocated according to a pattern of the synchronization signal so that various additional functions can be secured by transmitting a command from the touch screen to the active stylus pen. Receiving a touch screen driving signal from the active stylus pen by bringing the active stylus pen into contact with the touch screen;
Generating a pen driving signal from the active stylus pen to be synchronized with the received touch screen driving signal and outputting it to the touch screen;
Sensing a change in capacitance of the touch screen according to the touch screen driving signal and the pen driving signal by a touch driving device connected to the touch screen,
In the step of generating the pen driving signal from the active stylus pen and outputting it to the touch screen,
Generating a touch frame recognition signal for distinguishing a touch frame based on a sub-pulse corresponding to a part of each touch screen driving signal received from the touch screen; and
The pen driving signal is generated to be synchronized with a main pulse excluding the sub pulse from each touch screen driving signal, and the pen driving signal is converted to a touch frame according to the touch frame recognition signal so that additional pen information is reflected in the pen driving signal. Including the step of varying in units,
In the touch screen driving signal, the sub-pulse is allocated to a part of a 1-touch period, and the main pulse is allocated to a remaining period of the 1-touch period;
The touch screen drive signal further includes a beacon signal driven in a dummy touch period different from the first touch period,
The sub-pulse and the beacon signal are synchronization signals for synchronizing the main pulse and the pen driving signal, and each is implemented as a patterned ping signal. 24. The method of claim 23,
Generating a touch frame recognition signal based on the sub-pulse includes:
A first count value is generated by counting an interval between a first sub-pulse of one touch screen driving signal and a second sub-pulse of another touch screen driving signal adjacent to the one touch screen driving signal, and the first count value is A method of driving a touch sensing system for generating the touch frame recognition signal when a preset threshold value is exceeded. 24. The method of claim 23,
Generating a touch frame recognition signal based on the sub-pulse includes:
A method of driving a touch sensing system comprising counting the sub-pulses included in each touch screen driving signal to generate a second count value, and generating the touch frame recognition signal when the second count value meets a preset value. 24. The method of claim 23,
The step of varying the pen driving signal in units of touch frames according to the touch frame recognition signal so that the pen additional information is reflected in the pen driving signal,
A method of driving a touch sensing system in which a pulse amplitude of the pen driving signal is varied in units of touch frames according to the touch frame recognition signal. 24. The method of claim 23,
The step of varying the pen driving signal in units of touch frames according to the touch frame recognition signal so that the pen additional information is reflected in the pen driving signal,
A method of driving a touch sensing system in which a pulse duty of the pen driving signal is varied in units of touch frames according to the touch frame recognition signal. According to any one of claims 23 to 27,
The step of varying the pen driving signal in units of touch frames according to the touch frame recognition signal so that the pen additional information is reflected in the pen driving signal,
A method of driving a touch sensing system for allocating a pen driving signal reflecting the pen additional information by 1 bit to 1 touch frame. 24. The method of claim 23,
The additional pen information includes pen pressure information indicating pressure when the active stylus pen contacts the touch screen, and button status indicating whether at least one functional button provided in the active stylus pen and performing a specific function is activated. A method of driving a touch sensing system including information and pen identification information for distinguishing it from other active stylus pens. 24. The method of claim 23,
The beacon signal is a method of driving a touch sensing system including a pen operation mode, hovering or contact status, and whether or not tilt data is transmitted. delete 24. The method of claim 23,
The synchronization signal is a driving method of a touch sensing system implemented as a patterned Direct Sequence Spread Spectrum (DSSS) code. 24. The method of claim 23,
A method of driving a touch sensing system further comprising allocating a plurality of bits according to a pattern of the synchronization signal so that various additional functions can be secured by transmitting a command from the touch screen to the active stylus pen. .

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