KR20170027243A - Active stylus pen and touch sensing system and driving method of the same - Google Patents

Abstract

An active stylus pen of the present invention is an active stylus pen for generating a pen driving signal to be synchronized with a touch screen driving signal received from a touch screen and outputting it to the touch screen. The active stylus pen includes a pressure sensing part which senses a pressure when the touch screen is touched and generates writing pressure information, and a signal processing part which modulates the pen driving signal according to the signal level of the writing pressure information, and outputs the modulated signal as a pen driving signal reflecting the writing pressure information. So, it is possible to easily transmit the writing pressure information from the active stylus pen to a touch module without a separate communication block.

Description

TECHNICAL FIELD [0001] The present invention relates to an active stylus pen, a touch sensing system including the active stylus pen,

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

A user interface (UI) enables 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 infrared communication or radio frequency (RF) communication function, and the like. User interface technology has been developed to enhance the user's sensibility and ease of operation. Recently, the user interface has evolved into a touch UI, a voice recognition UI, a 3D UI, and the like.

The touch UI is essential for portable information devices. The touch UI is implemented by a method of forming a touch screen on the screen of a display device. Such a touch screen can be implemented in a capacitive manner. When a finger or a conductive material touches (or comes close to) the touch sensor, the touch screen having the capacitive touch sensor senses a change in capacitance due to the input of the touch screen drive signal, that is, Thereby detecting the 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 capacitance sensor may be connected in a one-to-one relationship with sensor wirings formed along one direction. The mutual capacitance sensor may be formed at the intersection of the sensor wirings orthogonal to each other with the dielectric layer interposed therebetween.

In recent years, not only a finger but also a stylus pen have been widely used as a human interface device (HID) in smart phones and smart books. The stylus pen has the advantage of being able to input more finely than the finger. There are passive and active stylus pens. In the passive type, it is difficult to detect the touch position because the capacitance change is small at the contact point with the touch screen. The active type generates the pen drive signal itself and outputs it to the contact point with the touch screen, so it is easier to detect the touch position than the passive type.

Recently, as the screen size of the touch screen is diversified, various functions such as the sensing of the touch input as well as the pressure signal processing when the stylus pen touches the touch screen are required. However, the conventional active stylus pen requires a separate communication block to transmit the pressure information to the touch module, as disclosed in Korean Patent Laid-Open Publication No. 10-2014-0043299, which increases the manufacturing cost.

Accordingly, an object of the present invention is to provide an active stylus pen capable of easily transmitting pressure information from an active stylus pen to a touch module without having a separate communication block, a touch sensing system including the same, and a driving method thereof have.

In order to achieve the above object, the active stylus pen of the present invention includes a pressure sensing unit for sensing pressure when touching a touch screen to generate pressure information, And a signal processing unit for generating a signal, and varying the pen driving signal so that a signal level of the pressure information is reflected on the pen driving signal.

The signal processing section modulates the pulse amplitude of the pen drive signal in accordance with the signal level of the pressure information.

The signal processing unit modulates the number of pulses of the pen driving signal generated during one touch sensor driving period according to the signal level of the pressure information.

The signal processing section modulates the pulse duty of the pen drive signal in accordance with the signal level of the pressure information.

The signal processing unit modulates the pen driving signal in units of one frame according to the signal level of the pressure information, and allocates the digital pen driving signal in which the pressure information is reflected, one bit per frame.

The signal processing section modulates either the pulse amplitude of the pen drive signal, the number of pulses, or the pulse duty within a range in which the touch input can be detected.

According to another aspect of the present invention, there is provided a touch sensing system including a touch screen, a touch driving device for applying a touch screen driving signal to the touch screen, sensing a change in capacitance of the touch screen, And an active stylus pen for transmitting. Here, the active stylus pen may include a pressure sensing unit for sensing pressure when touching the touch screen and generating pressure information, and a controller for generating the pen driving signal to synchronize with the touch screen driving signal received from the touch screen And a signal processing unit for varying the pen drive signal so that the signal level of the pressure information is reflected in the pen drive signal.

According to another aspect of the present invention, there is provided a method of driving a touch sensing system including the steps of: receiving an active stylus pen from a touch screen; receiving a touch screen driving signal from the active stylus pen; Generating a pen drive signal from the stylus pen and outputting the generated pen drive signal to the touch screen; sensing a capacitance change of the touch screen according to the touch screen drive signal and the pen drive signal in a touch drive device connected to the touch screen . The step of generating the pen driving signal from the active stylus pen and outputting the pen driving signal to the touch screen may include the steps of generating pressure information by sensing a pressure when the touch pen touches the touch screen, And varying the pen drive signal to be reflected in the pen drive signal.

The present invention reflects the pressure information on the pen driving signal in such a manner that the pulse amplitude and / or the number of pulses and / or the pulse duty of the pen driving signal are adjusted according to the signal level of the pressure information. The present invention finds not only a touch input position but also a pressure according to the size of data by a touch according to a pen drive signal reflecting pressure information. Therefore, the present invention eliminates the need for a separate communication block and logic block as in the prior art for pressure sensing, thereby greatly reducing the manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a touch sensing system of the present invention.
2 is a view illustrating a display device to which a touch sensing system according to an embodiment of the present invention is applied.
3 is a view showing an example of a touch screen implemented by a mutual capacitance sensor.
4 is a view showing an example of a touch screen implemented with a magnetic capacity sensor.
5 to 7 are views showing a touch driving device according to an embodiment of the present invention.
8 is a view showing that one frame is time-divided into a display driving period and a touch sensor driving period.
9 is a view showing an internal configuration of an active stylus pen according to the present invention.
10 is a view showing an operation procedure of an active stylus pen according to the present invention.
FIG. 11 is a diagram showing that a touch screen driving signal and a pen driving signal are synchronized with each other within a touch sensor driving period; FIG.
Figure 12 shows the waveforms of signals received and processed in the active stylus pen of Figure 9;
13 is a view showing in detail the internal structure of the active stylus pen shown in Fig. 9. Fig.
14 is a view showing that the sensitivity of the touch sensing signal is improved when the stylus pen is contacted as compared with a finger contact.
15 is a view showing the pressure sensing part of FIG. 13 in more detail;
16 is a view showing a change in touch raw data according to a change in touch pressure (pressure).
17 is a diagram showing an example of modulating the amplitude of the pen drive signal in accordance with the signal level of pen drive signal pressure information.
18 shows the relationship between the touch pressure, the amplitude of the pen drive signal, and the touch.
19 is a diagram showing an example of modulating the number of pulses of the pen drive signal according to the signal level of the pen drive signal pressure information.
Fig. 20 is a diagram showing the relationship between touch pressure, the number of pulses of the pen drive signal, and the touch. Fig.
21 is a diagram showing an example of modulating the pulse duty of the pen drive signal according to the signal level of the pressure information.
22 is a diagram showing the relationship between touch pressure, pulse duty of a pen drive signal, and touch data.
23 is a simulation result showing a data change by a touch according to a voltage change of a pen drive signal;
24 is a diagram showing an example in which the pen drive signal is modulated on a frame-by-frame basis in accordance with the signal level of the pressure information.
25A to 25C are diagrams showing examples in which the sensed value (data by touch) of the touch screen is changed according to the pressure information reflected on the pen drive signal
26 is a view showing a process of reflecting the pressure information on the pen driving signal and outputting the same;

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

[Touch Sensing  system]

1 schematically shows a 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 touch detection by the contact of a finger or a conductive object such as the active stylus pen 20, and is equipped with an electrostatic capacitive type touch screen integrally therewith. Here, the touch screen may be configured independently of the display panel for implementing the display, or may be embedded in the pixel array of the display panel. The specific configuration and operation of the display device 10 will be described later with reference to Figs. 2 to 8. Fig.

The active stylus pen 20 generates a pen driving signal on the basis of a touch screen driving signal received from the touch screen, and outputs the pen driving signal to a point of contact with the touch screen, thereby facilitating the touch position detection on the touch screen. The active stylus pen 20 senses the pressure (pressure) of the pen when it touches the touch screen and changes the pen driving signal so that the signal level of the pressure information is reflected in the pen driving signal. The touch sensing system analyzes a change of data (touch raw data) by a touch according to a pen drive signal, and senses a touch input position and a touch pressure (pressure) by the active stylus pen 20. The construction and operation of the active stylus pen 20 will be described later with reference to Figs. 9 to 26. Fig.

[Display device]

FIG. 2 shows a display device to which a touch sensing system according to an embodiment of the present invention is applied. FIG. 3 shows an example of a touch screen implemented as a mutual capacitance sensor. 4 shows an example of a touch screen implemented by a magnetic capacity sensor. 5 to 7 show a touch driving apparatus according to an embodiment of the present invention.

2 to 7, the display device 10 of the present invention may be a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP) ), An organic light emitting diode (OLED) display, and an electrophoresis (EPD) display device. In the following embodiments, 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 comprises a display module and a touch module.

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

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

The touch screen TSP implemented by the mutual capacitive sensor Cm includes Tx electrode lines, Rx electrode lines intersecting the Tx electrode lines, and a plurality of Rx electrode lines at the intersections of the Tx electrode lines and the Rx electrode lines, And the touch sensors Cm formed thereon. The Tx electrode lines are driving signal lines for applying a touch screen driving signal to each of the touch sensors Cm to supply electric charges to the touch sensors. The Rx electrode lines are sensor wirings connected to the touch sensors Cm to supply the charges of the touch sensors to the touch driver 18. [ In the mutual capacitance sensing method, a driving signal is applied to a Tx electrode through a Tx electrode line to supply a charge to a touch sensor (Cm), and a voltage is applied to the touch sensor (Cm) through an Rx electrode and an Rx electrode line By sensing the change in capacitance, the touch input can be detected.

The touch screen TSP implemented by the capacitance sensor Cs may be connected in a one-to-one relationship with the sensor wires 32 formed along one direction of the touch electrodes 31 as shown in FIG. The capacitance sensor Cs includes a capacitance formed in each of the electrodes 31. [ In the capacitance sensing method, when a touch screen driving signal is applied to the electrode 31 through the sensor wiring 32, the charge Q is accumulated in the touch sensor Cs. At this time, when a finger or a conductive object touches the electrode 31, the parasitic capacitance Cf is further connected to the capacitance sensor Cs to change the total capacitance value. If the capacitance value is changed between the finger-touched sensor and the non-touched sensor, the amount of charge sensed by the touch sensors is changed, thereby determining whether or not the finger is touched.

The touch screen TSP may be bonded onto the upper polarizer plate of the display panel DIS or between the upper polarizer plate of the display panel DIS and the upper substrate. In addition, the touch sensors Cm or Cs of the touch screen TSP may be embedded in the pixel array of the display panel DIS.

The touch driver 18 senses the amount of change in the charge of the touch sensor before and after touching to judge whether or not a conductive substance such as a finger (or a stylus pen) touches and its position.

The touch-driving device 18 of the present invention can be implemented as an IC (Integrate Circuit) package as shown in FIGS.

Referring to FIG. 5, the touch driver 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 generating unit 130, a multiplexer (MUX) 140, 150).

The touch sensor channel unit 100 is connected to the electrodes of the touch sensors through sensor wirings (or Rx electrode lines), and is connected to the Vcom buffer 110 and the multiplexer 140 through the switch array 120. The multiplexer 140 connects the sensor wires to the 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 the three sensor wirings in a time division manner. The multiplexer 140 sequentially selects the sensor wirings to be connected to the channel of the touch IC (TIC) in response to the MUX control signals MUX C1 to C3. The multiplexer 140 is connected to the channels of the touch IC (TIC) through the touch lines.

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

The timing control signal generator 130 generates timing control signals for controlling operation timings of the display driving circuit and the touch IC (TIC). The display driving circuit includes a data driving circuit (12) and a gate driving circuit (14) for writing data of an input image to a pixel.

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

The timing control signal generating unit 130 generates a touch enable signal TEN defining the display driving period T1 and the touch sensor driving period T2 as shown in FIG. Synchronize. The display driving circuit writes data to the pixels during the first level period of the touch enable signal TEN. The touch IC (TIC) senses the touch input by driving the 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 low level, the second level may be a high level, and vice versa.

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

The noise may be increased in the touch sensor signal according to the change of the input image data. The DTX compensator 150 analyzes the input image data, removes noise components from the touch raw data according to the gradation change of the input image, and transmits the same to the touch IC (TIC). DTX stands for Display and Touch crosstalk. The contents of the DTX compensation unit 150 are described in detail in the patent application No. 10-2012-0149028 (filed December 19, 2012), which is 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 compensation unit 150 is not necessary and can be omitted. In FIG. 5, DTX DATA is the output data of the DTX compensator 150.

The touch IC TIC drives the multiplexer 140 during the touch sensor driving period T2 in response to the touch enable signal TEN from the timing control signal generating unit 130 and outputs the signal through the multiplexer 140 and the sensor wirings And receives the charge of the touch sensor. In FIG. 5, the MUXs C1 to C3 are signals for selecting the channel of the multiplexer.

The touch IC (TIC) detects the amount of charge change before and after the touch input from the touch sensor signal, compares the amount of charge change with a predetermined threshold value, and determines the position of the touch sensor having the charge variation amount equal to or larger 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. The touch IC (TIC) includes an amplifier for amplifying the charge of the touch sensor, an integrator for accumulating the charge received from the touch sensor, an ADC (Analog to Digital Converter) for converting the voltage of the integrator into digital data, and an arithmetic logic section. The arithmetic logic unit compares the touch raw data output from the ADC with a threshold value, and executes a touch recognition algorithm that determines a touch input and calculates coordinates based on the comparison result.

The driver IC (DIC) and the touch IC (TIC) can transmit and receive signals through the SPI (Serial Peripheral Interface) interface.

The host system 19 refers to a system body of an electronic apparatus to which the display apparatus 10 of the present invention is applicable. The host system 19 may be any one of a phone system, a television 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 the input image data RGB to the driver IC DIC and receives the touch input data TDATA XY from the touch IC TIC and outputs an application associated with the touch input, .

Referring to FIG. 6, the touch driver 18 includes a driver IC (DIC) and an MCU (Micro Controller Unit).

The driver IC DIC includes a touch sensor channel unit 100, a Vcom buffer 110, a switch array 120, a first timing control signal generating unit 130, a multiplexer 140, a DTX compensating unit 150, Unit 160, a second timing control signal generator 170, and a memory 180. This embodiment differs from the embodiment of FIG. 5 in that the sensing unit 160 and the second timing control generator 170 are integrated in the driver IC (DIC). The first timing control generator 130 is substantially the same as that of FIG. Accordingly, the first timing control generator 130 generates timing control signals for controlling the operation timing of the display driving circuit and the touch IC (TIC).

The sensing unit 160 includes an amplifier for amplifying the charge of the touch sensor, an integrator for accumulating the charge received from the touch sensor, and an ADC for converting the voltage of the integrator into digital data. Touch raw data (TDATA) output from the ADC is sent to the MCU. The second timing control generator 170 generates a timing control signal for controlling the operation timing of the multiplexer 140, the sensing unit 160, a clock, and the like. The DTX compensation section 150 in the driver IC (DIC) may be omitted. The memory 180 temporarily stores data (TDATA) under the control of the second timing control generator 170.

Driver IC (DIC) and MCU can send and receive signals through SPI (Serial Peripheral Interface) interface. The MCU compares the data (TDATA) with a threshold value with a touch, executes a touch recognition algorithm to determine the touch input according to the result of the comparison and to calculate coordinates.

Referring to FIG. 7, the touch driver 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 generating unit 130, a multiplexer 140, a DTX compensating unit 150, 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 in a driver IC (DIC). The MCU 18 compares the data TDATA with a threshold value by touching, executes a touch recognition algorithm for determining a touch input according to the comparison result, and calculating coordinates.

The memory MEM stores a register setting value related to the timing information necessary for the operation of the display driving circuit and the sensing unit 160. [ The register set value is loaded from the memory MEM to 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 generator 16 and the second timing control signal generator 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 cope with the model change by changing the register setting value of the memory MEM without structural modification of the driving apparatus.

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

The display panel DIS includes a liquid crystal layer formed between two substrates. The pixel array of the display panel DIS includes pixels formed in the pixel region defined by the data lines (D1 to Dm, m is a positive integer) and the gate lines (G1 to Gn, n is a positive integer) . Each of the pixels includes a TFT (Thin Film Transistor) formed at intersections of the data lines D1 to Dm and the gate lines G1 to Gn, a pixel electrode for charging a data voltage, A storage capacitor (Cst) for maintaining a voltage, and the like.

A black matrix, a color filter, and the like may be formed on the upper substrate of the display panel DIS. The lower substrate of the display panel DIS may be implemented with a COT (Color Filter On TFT) structure. In this case, the black matrix and the color filter can 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 the upper substrate or the lower substrate of the display panel DIS. On the upper substrate and the lower substrate of the display panel DIS, a polarizing plate is attached, and an alignment film for forming a pre-tilt angle of the liquid crystal on the inner surface in contact with the liquid crystal is formed. 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 below the rear surface of the display panel DIS. The backlight unit is implemented as an edge type or direct type backlight unit, and irradiates the display panel (DIS) with light. The display panel DIS may be implemented in any known liquid crystal mode such as TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode.

The display driving circuit includes a data driving circuit 12, a gate driving circuit 14, and a timing controller 16, and writes 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 gamma compensation voltage to output a data voltage. The data voltage output from the data driving circuit 12 is supplied to the data lines D1 to Dm. The gate drive circuit 14 sequentially supplies a gate pulse (or a scan pulse) synchronized with the data voltage to the gate lines G1 to Gn to select the pixel line of the display panel DIS to which the data voltage is written. The gate drive 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 DE and a main clock MCLK input from the host system 19 And synchronizes the operation timings of the data driving circuit 12 and the gate driving circuit 14 with each other. The scan timing control signal includes a gate start pulse (GSP), a gate shift clock, a gate output enable signal (GOE), and the like. The data timing control signal includes a source sampling clock (SSC), a polarity control signal (Polarity), a source output enable signal (SOE), and the like.

The host system 19 transmits the timing signals Vsync, Hsync, DE and MCLK to the timing controller 16 together with the digital video data RGB and outputs the touch coordinate information XY ). ≪ / RTI >

On the other hand, the touch enable signal TEN of FIG. 8 may be generated in the host system 19. During the display driving period T1, the data driving circuit 12 supplies the data voltage to the data lines D1 to Dm under the control of the timing controller 16, and the gate driving circuit 14 supplies the data voltages to the timing controller 16, A gate pulse synchronized with the data voltage is sequentially supplied to the gate lines G1 to Gn under the control of the control circuit. On the other hand, during the display driving period T1, the touch driving device 18 stops operating.

During the touch sensor driving period T2, the touch driving device 18 applies a touch screen driving signal to the touch sensors of the touch screen TSP. Meanwhile, during the touch sensor driving period T2, the display driving circuits 12, 14, and 16 are turned on in order to minimize the parasitic capacitance between the signal lines D1 to Dm, G1 to Gn connected to the pixels and the touch sensors It is possible to supply an AC signal having the same amplitude and the same phase as the touch screen driving signal to the signal lines D1 to Dm and G1 to Gn. In this case, the display noise mixed into the touch sensing signal is remarkably reduced, and the accuracy of the touch sensing is increased.

[ Stylus  pen]

9 shows the internal structure of the active stylus pen 20 according to the present invention.

9, the active stylus pen 20 includes a housing 280, a conductive tip 210 protruding from one side of the housing 280, and a conductive tip 210 connected to the conductive tip 210 inside the housing 280 A switching unit 220 and a switching unit 220. The switching unit 220 includes a receiving unit 230 for receiving a touch screen driving signal input from the conductive tip 210, A signal processing unit 250 for generating a digital pen driving signal including the pressure information and level shifting the digital pen driving signal generated in the signal processing unit 250 to an analog level, A power supply unit 260 for generating a driving power required for the operation, and an input / output interface 270. The power supply unit 260 is connected to the input /

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 at that point of contact is coupled to the touch screen TSP. The conductive tip 210 receives the touch screen drive signal from the touch screen TSP at the touch point and then transmits the pen drive signal generated inside the active stylus pen 20 to the touch screen TSP Point.

The switching unit 220 electrically connects the conductive tip 210 and the receiving unit 230 for a first time when the conductive tip 210 contacts the touch screen TSP of the display device 10. [ And electrically connects the conductive tip 210 and the driving unit 240 for a second time period to temporally separate the timing of receiving the touch screen driving signal and the timing of transmitting the pen driving signal. Since the conductive tip 210 also serves as 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 a touch screen driving signal input from the conductive tip 210 through the switching unit 220. The receiving unit 230 includes a comparator, compares the amplified signal with a preset reference voltage, and outputs the result to the signal processing unit 250.

The signal processing unit 250 analyzes the output signal of the comparator input from the receiving unit 230 for more than one frame to generate a pen driving signal synchronized with the touch screen driving signal and then outputs the pen driving signal to the pressure sensing unit And then outputs the pen driving signal to the driving unit 240. The pen driving signal generating unit 240 generates a pen driving signal based on the pen driving signal.

The driver 240 includes a level shifter to shift a pen drive signal at a digital level 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 unit 260 according to a button push operation of the user, and can supply necessary power to the receiving unit 230, the driving unit 240, and the signal processing unit 250.

10 shows the operation procedure of the active stylus pen 20 according to the present invention.

Referring to FIG. 10, the conductive tip 210 contacts a predetermined point of the touch screen TSP (S1, S2) while the power is applied through the input / output interface 270 and the power supply unit 260.

During the driving of the touch sensor, a touch screen driving signal is supplied to each touch sensor of the touch screen (TSP). During the touch sensor driving period, the conductive tip 210 is coupled to the touch screen TSP at the touch point to sense the touch screen drive signal received from the touch screen TSP, and transmits 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 comparison result to the signal processing unit 250 (S3).

The signal processing unit 250 analyzes the comparator output signal inputted from the receiving unit 230 to determine timing to be synchronized with the touch screen driving signal, and generates a pen driving signal in accordance with the synchronizing timing (S4, S5). The signal processing unit 250 modulates the pulse amplitude and / or the number of pulses and / or the pulse duty of the pen driving signal in accordance with the pressure information inputted from the pressure sensing unit, and then outputs the pen driving signal reflecting the pressure information to the driving unit 240 (S6, S7).

The driving unit 240 shifts the voltage level of the pen driving signal through the level shifter and outputs the level shifted pen driving signal to the conductive tip 210 through the switching unit 220. The conductive tip 210 applies a pen drive signal to the touch point of the touch screen.

The pen drive signal has its pulse amplitude and / or number of pulses and / or pulse duty adjusted according to the signal level of the pressure information. When the pulse amplitude and / or the number of pulses and / or the pulse duty of the pen drive signal changes, the magnitude of the sensing value (data by touch) sensed from the touch point changes. The touch driving device 18 can analyze the size of data by a touch to find not only the touch position but also the touch pressure (pressure).

FIG. 11 shows that the touch screen driving signal and the pen driving signal are synchronized with each other within the touch sensor driving period. Figure 12 shows the waveforms of the signals received and processed in the active stylus pen of Figure 9;

11 and 12, after the active stylus pen 20 is brought into contact with the touch screen TSP following the ON operation of the active stylus pen 20, ) And the transmission period Ta of the pen drive signal Ps is provided with a signal switching interval of at least one frame, and the stability of the operation is ensured. The signal processing unit 250 determines a synchronization timing between the touch screen driving signal Ts and the pen driving signal Ps using the signal switching period and generates a pen driving signal Ps reflecting the pressure information.

A process (Ta) of transmitting a pen driving signal (Ps) synchronized with the touch screen driving signal (Ts) to the touch screen (TSP) through the conductive tip (210) The process (Ra) of receiving the touch screen driving signal (Ts) is repeatedly and alternately performed.

12, the reception interval Ra of the touch screen driving signal Ts and the transmission interval Ta of the pen driving signal Ps are shown to be equal to each other. Actually, however, the time width of the reception interval Ra is The smaller the time required for the touch response, the larger the time width of the transmission period Ta is.

Fig. 13 shows the internal structure of the active stylus pen 20 shown in Fig. 9 in more detail.

13, the input / output stage 205 of the active stylus pen 20 further includes a conductive tip 210 and a pressure sensing unit 215 in addition to the switching unit 220. The pressure sensing unit 215 senses the pressure of the active stylus pen 20 on the touch screen TSP and transmits the sensed pressure to the signal processing unit 250.

The receiving section 230 of the active stylus pen 20 includes a receiving buffer 231, an amplifier 233, and a comparator 235. The reception buffer 231 receives the touch screen driving signal Ts transmitted through the switching unit 220 and applies the received touch screen driving signal Ts to the amplifier 233. The amplifier 233 includes at least two stages to amplify the touch screen driving signal Ts at the analog level to increase the sensitivity of the received signal. The comparator 235 compares the amplified signal from the amplifier 233 with an internal reference voltage to generate a comparator output signal COM at a digital level above the reference voltage or below the reference voltage. Here, when the amplifier 233 is implemented as an inverting amplifier, the comparator 235 uses a signal equal to or higher than the reference voltage as the comparator output signal COM. When the amplifier 233 is implemented as a non-inverting amplifier, Can be used as the comparator output signal COM.

The signal processing unit 250 of the active stylus pen 20 determines the timing of synchronizing with the touch screen driving signal Ts based on the comparator output signal COM as described above, Thereby generating a driving signal. The signal processing unit 250 modulates the pen driving signal based on the pressure information inputted from the pressure sensing unit 215 and outputs the pen driving signal Ps reflecting the pressure information. Conventionally, the pressure information is transmitted from the stylus pen to the touch module using a separate communication block provided in the stylus pen. In the touch module, the pressure magnitude is sensed using a separate logic block. On the other hand, in the present invention, a separate communication block and a logic block are not required for pressure sensing. In the present invention, the pressure information is encoded into the pen drive signal Ps in such a manner that the pulse amplitude and / or the number of pulses and / or the pulse duty of the pen drive signal Ps are adjusted according to the signal level of the pressure information, The change in size of the data is sensed by a touch according to the pen drive signal Ps, and accordingly, not only the touch input position but also the touch pressure is decoded.

The driving unit 240 of the active stylus pen 20 includes a level shifter 243 and a transmission buffer 241 to convert a pen driving signal Ps at a digital level input from the signal processing unit 250 into an analog level, (220). Then, the switching unit 220 transmits the pen driving signal Ps to the conductive tip 210.

14 is a simulation result showing that the sensitivity of the touch sensing signal is improved when the active stylus pen is contacted as compared with the finger touching.

Referring to FIG. 14, the applicant of the present invention has experimentally measured the intensity of each touch sensing signal when touching the touch screen with the active stylus pen and when touching the touch screen with the finger. As a result of the experiment, when the intensity of the sensing signal when the stylus pen touches the touch screen is large and the value of the coupled capacitance between the touch screen and the conductive tip is large (i.e., the larger the pulse amplitude of the pen driving signal Ps, The intensity of the sensing signal (data with a touch) becomes larger as the number of pulses of the pen drive signal Ps increases and / or the pulse duty of the pen drive signal Ps increases.

[ Pressure Sensing  measures]

Fig. 15 shows the pressure sensing unit 215 of Fig. 13 in more detail. 16 shows the change of the touch raw data according to the change of the touch pressure (pressure). Fig. 17 shows an example of modulating the amplitude of the pen drive signal in accordance with the signal level of the pressure information to generate the pen drive signal, Fig. 18 shows the relationship between the touch pressure, the amplitude of the pen drive signal, Show. FIG. 19 shows an example of modulating the number of pulses of the pen drive signal according to the signal level of the pen drive signal pressure information, and FIG. 20 shows the relationship between the touch pressure, the number of pulses of the pen drive signal, and the data by touch. 21 shows an example of modulating the pulse duty of the pen drive signal according to the signal level of the pressure information, and Fig. 22 shows the relationship between the touch pressure, the pulse duty of the pen drive signal, and the touch.

The pressure sensing unit 215 may include a variable resistance unit 215A, a voltage conversion unit 215B, and an ADC 215C, as shown in FIG. The variable resistance portion 215A changes its resistance value when the pressure magnitude changes. The voltage converter 215B generates an output voltage corresponding to the resistance value of the variable resistor 215A. The ADC 215C converts the voltage corresponding to the pressure magnitude into a digital signal and outputs the pressure information to the signal processing unit 250. [ The variable resistor section 215A may be replaced with a variable capacitor, in which case the voltage conversion section 215B may be replaced by an RC delay element. Also, the ADC 215C may be replaced by a comparator.

The signal processing unit 250 may generate the pen driving signal Ps reflecting the pressure information by modulating the pulse amplitude of the pen driving signal synchronized with the touch screen driving signal Ts according to the signal level of the pressure information as shown in FIG. have. At this time, the signal processing unit 250 may vary the pulse amplitude of the pen drive signal Ps to indicate the pressure information within a range in which the touch input can be detected. In other words, the pulse amplitude PAM2 of the pen drive signal Ps may be equal to the pulse amplitude PAM1 of the touch screen drive signal Ts when no pressure information is input as shown in Fig. 18A, The signal level of the pressure-sensitive information is proportionally larger than the pulse amplitude PAM1 of the touch screen drive signal Ts. The larger the pulse amplitude PAM2 of the pen drive signal Ps, the larger the size of the touch sensing signal (data with touch) that is sensed by the touch screen, and the touch drive device, as shown in FIG. 18B, The touch pressure (pressure) can be determined. In other words, as shown in FIG. 16, the touch driving apparatus can determine that the pressure increases as the data size increases.

On the other hand, in order to adjust the pulse amplitude PAM2 of the pen drive signal Ps, the signal processing unit 250 can modulate the high level voltage HLV of the pen drive signal Ps in accordance with the signal level of the pressure information .

The signal processing unit 250 modulates the number of pulses of the pen driving signal outputted during one touch sensor driving period T2 in synchronization with the touch screen driving signal Ts according to the signal level of the pressure information as shown in FIG. It is possible to generate the pen driving signal Ps reflected. At this time, the signal processing unit 250 may vary the number of pulses of the pen drive signal Ps to represent the pressure information within a range in which the touch input can be detected. The pulse number j of the pen drive signal Ps during one touch sensor drive period T2 is within the pulse number k of the touch screen drive signal Ts as shown in FIG. The level can be increased gradually. As the number of the pen drive signals Ps increases, the size of the touch sensing signal (data as a touch) sensed by the touch screen may be increased. As shown in FIG. 20B, The touch pressure (pressure) can be determined. In other words, as shown in FIG. 16, the touch driver can determine that the pressure increases as the size of the data increases with the touch.

The signal processing unit 250 can generate the pen driving signal Ps reflecting the pressure information by modulating the pulse duty of the pen driving signal synchronized with the touch screen driving signal Ts according to the signal level of the pressure information as shown in FIG. have. At this time, the signal processing unit 250 can vary the pulse duty of the pen drive signal Ps to display the pressure information within a range in which the touch input can be detected.

In other words, the pulse duty PD2 of the pen drive signal Ps may be the same as the pulse duty PD1 of the touch screen drive signal Ts when no pressure information is input as shown in Fig. 22 (A) The signal level of the pressure-sensitive information is proportionally larger than the pulse duty PD1 of the touch screen drive signal Ts. The larger the pulse duty PD2 of the pen drive signal Ps, the larger the size of the touch sensing signal (data as a touch) sensed by the touch screen may be, and as a result, The touch pressure (pressure) can be determined. In other words, as shown in FIG. 16, the touch driver can determine that the pressure increases as the size of the data increases with the touch.

The signal processing unit 250 simultaneously modulates at least two pulse amplitudes, pulse numbers, and pulse durations of the pen driving signal synchronized with the touch screen driving signal Ts according to the signal level of the pressure information, The driving signal Ps may be generated.

23 is a simulation result showing a change in data with a touch according to a change in the high level voltage of the pen drive signal Ps.

23, when the high-level voltage HLV of the pen drive signal Ps is changed from Ps_High1 to Ps_High2 according to the change in the pressure, the size of the data is increased from 360 to 600 by touch . Similarly, when the number of pulses and / or pulse duty of the pen drive signal Ps is varied according to the change in the pressure, the magnitude of the data changes with the touch. The touch-driving device can sense the pressure level based on the amount of change of data by such a touch.

24 shows an example in which the pen drive signal Ps is modulated on a frame-by-frame basis in accordance with the signal level of the pressure information. 25A to 25C show an example in which the sensed value (data by touch) of the touch screen changes according to the pressure information reflected on the pen drive signal Ps. 26 shows a process of reflecting the pressure information on the pen driving signal in the signal processing unit 250 and outputting the same.

Referring to FIGS. 24 to 26, the pressure sensing unit 215 senses the pressure of the pressure, and converts the sensed pressure into a binary value to generate pressure level information of the digital level (S1, S2). The signal processing unit 250 modulates the pen drive signal Ps in units of one frame according to the signal level of the pressure information, allocates one bit of the digital pen drive signal Ps reflecting the pressure information to the one frame, The driving signal Ps can be generated (S3, S4). For example, the signal processing unit 250 may represent digital information "0" and "1" by making the pulse amplitudes A1 and A2 of the pen drive signal Ps1 different from each other, 0 "and" 1 ", which are digital information, or the pulse duty D1 and D2 of the pen drive signal Ps3 are made different from each other by making the number of pulses (3, Digital information "0" and "1" can be expressed. The logical value of the pen drive signal Ps for expressing the signal level of the pressure information can be controlled in units of one frame. In this case, the 256 pressure levels can be represented by an 8-bit pen drive signal Ps implemented through eight frames. The digital pen drive signal Ps having the predetermined bit is amplified to an analog level through the driver 240 and then output to the touch screen (S5, S6). As shown in Figs. 25A and 25B, the touch sensing value (touch-based data) corresponding to the pen driving signal Ps represented by the logical value "1 " Value. The touch driving device 18 of the display device 10 senses the 8-bit pressure information on the basis of the magnitude of the touch sensing value according to the pen driving signal Ps and can determine the pressure of the pen accordingly.

On the other hand, as described above, m frames are required to load the m-bit pressure information on the pen driving signal Ps. The signal processing unit 250 may allocate a start frame between m frames as shown in FIG. 24 in order to divide the pressure information in units of m bits. In the start frame, a start pen drive signal for dividing the pressure information is assigned. The start-up pen drive signal is used as a flag signal, and the pulse amplitude and / or the number of pulses and / or the pulse duty are different from the pen drive signal Ps represented by "1" or "0". Specifically, the pulse amplitude of the starting pen driving signal is smaller than the pulse amplitude of the pen driving signal Ps represented by "0 ", and the number of pulses of the starting pen driving signal is represented by" Ps, and the pulse duty of the pen drive signal for start may be smaller than the pulse duty of the pen drive signal Ps represented by "0 ". By dividing the pressure information by predetermined bits through the separate start frame, it is possible to accurately transmit the pressure information to the touch driving device 18 of the display device 10 even when the load of the touch screen is large.

As described above, according to the present invention, the pressure information is reflected on the pen drive signal in such a manner that the pulse amplitude and / or the number of pulses and / or the pulse duty of the pen drive signal are adjusted according to the signal level of the pressure information, After detecting the size change of the data by the touch according to the pen drive signal, it finds not only the touch input position but also the touch pressure. Therefore, the present invention eliminates the need for a separate communication block and logic block as in the prior art for pressure sensing, thereby greatly reducing the manufacturing cost.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

10: display device 18: touch drive device
20: Stylus pen 215: Pressure sensing unit
210: Conductive tip 220:
230: Receiving unit 231: Receiving buffer
233: Amplifier 235: Comparator
240: driving unit 241: transmission buffer
243: level shifter 250: signal processor

Claims (18)

A pressure sensing unit that senses a pressure when touching the touch screen to generate pressure information; And
And a signal processor for generating a pen drive signal to be synchronized with a touch screen drive signal received from the touch screen, and varying the pen drive signal so that a signal level of the pressure information is reflected in the pen drive signal. The method according to claim 1,
The signal processing unit,
And modulates the pulse amplitude of the pen drive signal in accordance with the signal level of the pressure information. The method according to claim 1,
The signal processing unit,
And modulates the number of pulses of the pen driving signal generated during one touch sensor driving period in accordance with the signal level of the pressure information. The method according to claim 1,
The signal processing unit,
And modulates the pulse duty of the pen drive signal according to the signal level of the pressure information. 5. The method according to any one of claims 1 to 4,
The signal processing unit,
Wherein the pen driving signal is modulated on a frame-by-frame basis in accordance with the signal level of the pressure information, and the digital pen driving signal reflecting the pressure information is allocated in units of 1 bit per frame. 6. The method of claim 5,
The signal processing unit,
And the pulse duty, pulse number and pulse duty of the pen drive signal within a range in which touch input detection is possible. touch screen;
A touch driver that applies a touch screen driving signal to the touch screen and senses a capacitance change of the touch screen; And
And an active stylus pen for generating a pen driving signal and transmitting the pen driving signal to the touch screen,
The active stylus pen includes:
A pressure sensing unit sensing the pressure when the touch screen is contacted to generate pressure information; And
And a signal processing unit for generating the pen driving signal to be synchronized with a touch screen driving signal received from the touch screen and varying the pen driving signal so that the signal level of the pressure information is reflected in the pen driving signal, . 8. The method of claim 7,
The signal processing unit,
And modulates the pulse amplitude of the pen drive signal according to a signal level of the pressure information. 8. The method of claim 7,
The signal processing unit,
And modulates the number of pulses of the pen driving signal generated during one touch sensor driving period according to a signal level of the pressure information. 8. The method of claim 7,
The signal processing unit,
And modulates a pulse duty of the pen drive signal according to a signal level of the pressure information. 11. The method according to any one of claims 7 to 10,
The signal processing unit,
Wherein the pen drive signal is modulated in units of one frame according to a signal level of the pressure information, and the digital pen drive signal reflecting the pressure information is allocated to one frame in one frame. 12. The method of claim 11,
The signal processing unit,
The number of pulses, and the pulse duty of the pen drive signal within a range in which touch input detection is possible. Contacting the active stylus pen with a touch screen to receive a touch screen drive signal from the active stylus pen,
Generating a pen driving signal in the active stylus pen so as to be synchronized with the received touch screen driving signal and outputting the pen driving signal to the touch screen;
Sensing the capacitance change of the touch screen in accordance with the touch screen drive signal and the pen drive signal in a touch drive device connected to the touch screen,
Generating the pen driving signal from the active stylus pen and outputting the pen driving signal to the touch screen,
Sensing pressure at the time of contact with the touch screen to generate pressure information; And
And varying the pen drive signal so that the signal level of the pressure information is reflected in the pen drive signal. 14. The method of claim 13,
Wherein the step of varying the pen drive signal comprises:
And modulating a pulse amplitude of the pen drive signal according to a signal level of the pressure information. 14. The method of claim 13,
Wherein the step of varying the pen drive signal comprises:
Wherein the number of pulses of the pen drive signal generated during one touch sensor driving period is modulated according to a signal level of the pressure information. 14. The method of claim 13,
Wherein the step of varying the pen drive signal comprises:
Wherein the pulse duty of the pen drive signal is modulated according to a signal level of the pressure information. 17. The method according to any one of claims 13 to 16,
Wherein the step of varying the pen drive signal comprises:
And modulating the pen drive signal in units of frames in accordance with the signal level of the pressure information, and allocating the digital pen drive signal reflecting the pressure information to the one frame at a time. 18. The method of claim 17,
Wherein the step of varying the pen drive signal comprises:
The number of pulses, and the pulse duty of the pen drive signal within a range in which touch input detection is possible.

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