KR102022528B1 - Touch sensing system and driving method thereof - Google Patents

Abstract

The present invention relates to a touch sensing system and a driving method thereof, including: a touch screen including touch sensors; And a touch sensing circuit applying a driving signal to the touch sensors. At least one of the width, number, and voltage of the driving signal is controlled in proportion to the RC delay of the touch screen. The touch screen is divided into a number of blocks. Each of the blocks includes two or more lines to which the driving signal is applied. The width, number, and voltage of the driving signals are the same in one block. At least one of a width, a number, and a voltage of the driving signal is different between the blocks.

Description

TOUCH SENSING SYSTEM AND DRIVING METHOD THEREOF}

The present invention relates to a touch sensing system and a driving method thereof.

A user interface (UI) enables communication between a person (user) and various electric and electronic devices, so that the user can easily control the device as desired. Representative examples of the user interface include a keypad, a keyboard, a mouse, an On Screen Display (OSD), a remote controller having infrared communication or radio frequency (RF) communication. User interface technology continues to evolve in the direction of increasing user sensitivity and ease of operation. Recently, user interfaces have evolved into touch UIs, voice recognition UIs, 3D UIs, and the like.

Touch UI is being adopted to portable information devices, and it is being applied to home appliances. The capacitive touch sensing system has the advantages that the touch screen structure has higher durability and clarity than the conventional resistive method, and can be applied to various applications because multi-touch recognition and proximity touch recognition are possible.

The size of the mobile information terminal applying the touch UI is increasing. In the future, the touch UI is expected to be applied to large display devices such as computer monitors. As the size of the touch screen increases, the wires of the touch screen become longer, and the resistance and capacitance of the touch screen increase, resulting in an increase in the RC delay of the driving signal applied to the touch screen. 1 and 2 illustrate these RC delays.

As the size of the touch screen TSP increases, the difference of the RC delay increases according to the position of the touch screen TSP. As the size of the touch screen TSP increases, the sensing period becomes longer, so that the touch report rate is lowered. The lower the touch report rate, the worse the touch sensitivity. The touch report rate refers to a speed or frequency (Hz) of analyzing touch raw data obtained by sensing touch sensors in a touch screen during sensing, calculating coordinates, and transmitting the coordinate information to an external host system. do. The higher the touch report rate, the higher the touch sensitivity that a user feels because of the delay between touch input and coordinate recognition.

FIG. 1 is a diagram illustrating a part of a mutual capacitance touch screen (TSP). In FIG. 1, Tx1 to Tx5 are Tx lines to which a driving signal is applied, and Rx1 to Rx6 are Rx lines that receive voltages of the touch sensors Cm. A read-out integrated circuit (ROIC) is connected to the touch screen TSP. The ROIC applies a driving signal to the Tx lines Tx1 to Tx5 and receives the voltages of the touch sensors Cm through the Rx lines Rx1 to Rx6. Since touch sensors Cm close to the ROIC have a small RC delay, a large amount of charge (FIG. 2, ΔQ1) is charged when a driving signal is applied. In comparison, touch sensors far from the ROIC have a small charge amount (Fig. 2, ΔQ2) because of the large RC delay. Therefore, the farther the drive signal is applied from the touch screen TSP, the smaller the charge charge amount of the touch sensor Cm due to the RC delay. Done.

The present invention provides a touch sensing system and a driving method thereof that can respond to enlargement of a touch screen.

The touch sensing system of the present invention includes a touch screen including touch sensors; And a touch sensing circuit applying a driving signal to the touch sensors.

At least one of the width, number, and voltage of the driving signal is controlled in proportion to the RC delay of the touch screen.
The touch screen is divided into a number of blocks. Each of the blocks includes two or more lines to which the driving signal is applied. The width, number, and voltage of the driving signals are the same in one block. At least one of a width, a number, and a voltage of the driving signal is different between the blocks.

According to the present invention, by controlling one or more of the width, number, and voltage of the driving signal in proportion to the RC delay of the touch screen, even when the size of the touch screen is increased, the RC delay can be compensated to uniformize the charging characteristics of the touch sensors. The charging amount of the sensors can be increased.

1 is a view illustrating a part of a mutual capacitive touch screen.
FIG. 2 is a diagram illustrating a phenomenon in which the amount of charges charged in the touch sensors is uneven due to the RC delay of the touch screen.
3 is a diagram illustrating a touch sensing system according to an embodiment of the present invention.
FIG. 4 is an equivalent circuit diagram of the touch screen shown in FIG. 3.
5 to 7 illustrate various combinations of a display panel and a touch screen.
8 is a circuit diagram showing an integrator of the Rx driving circuit.
9 is a waveform diagram illustrating changes in voltage of a touch sensor before and after a touch.
10 is a diagram illustrating an example of connecting a touch screen and a touch sensing circuit in the touch sensing system according to the present invention.
FIG. 11 is a diagram illustrating a split driving method of a touch screen in the touch sensing system as shown in FIG. 10.
12 is a waveform diagram illustrating a driving signal according to an exemplary embodiment of the present invention.
FIG. 13 shows a driving signal applied to a touch sensor having a large RC delay in comparison with the prior art and the present invention.
14 shows an example of a drive signal generator according to an embodiment of the present invention.
FIG. 15 is a waveform diagram illustrating input and output signals of the driving signal generator shown in FIG. 14.
16 and 17 are waveform diagrams showing driving signals according to another embodiment of the present invention.

The touch sensing system of the present invention may be implemented as a capacitive touch screen that senses a touch input through a plurality of capacitive sensors. The capacitive touch screen includes a plurality of touch sensors. Each of the touch sensors includes a capacitance when viewed in equivalent circuitry. The capacitance can be divided into self capacitance or mutual capacitance. In the following embodiments, the mutual capacitive touch screen is illustrated, but the touch sensing system of the present invention is not limited to the mutual capacitive touch screen.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like numbers refer to like elements throughout. In the following description, when it is determined that a detailed description of known functions or configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

3 to 7, the touch sensing system of the present invention includes a touch screen (TSP), a touch screen driving circuit, and the like. The touch screen TSP is bonded on the upper polarizing plate POL1 of the display panel DIS as shown in FIG. 5, or is formed between the upper polarizing plate POL1 and the upper substrate GLS1 of the display panel DIS as shown in FIG. 6. Can be. In addition, the touch sensors Cm of the touch screen TSP are embedded in the lower substrate or in the in-cell type together with the pixel array in the display panel DIS as shown in FIG. 7. It can be built in between. Substrates of the display panel may be made of glass or film substrates. 5 to 7, "PIX" is a pixel electrode of a liquid crystal cell, and GLS2 is a substrate. POL, POL1, and POL2 mean polarizing plates.

The display panel DIS of the present invention is a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting diode display (Organic) It may be implemented as a display panel of a flat panel display such as a light emitting display (OLED), an electrophoretic display device (EPD), and the like. The pixel array of the display panel DIS includes pixels formed in the pixel area defined by the data lines D1 to Dm, where m is a positive integer, and the gate lines G1 to Gn, where n is a positive integer. . Each pixel may include TFTs (Thin Film Transistor), a storage capacitor (Cst), or the like. TFTs are formed at intersections of the data lines D1 to Dm and the gate lines G1 to Gn. A color filter array may be formed in the display panel DIS to implement color.

The display driving circuit includes the data driving circuit 12, the scan driving circuit 14, and the timing controller 20 to write the video data voltage of the input image to the pixels of the display panel DIS. The data driving circuit 12 converts the digital video data RGB input from the timing controller 20 into an analog positive / negative gamma compensation voltage and outputs a data voltage. The data voltage output from the data driver circuit 12 is supplied to the data lines D1 to Dm. The scan driving circuit 14 sequentially supplies gate pulses (or scan pulses) synchronized with the data voltages to the gate lines G1 to Gn to select a line of the display panel DIS to which the data voltages are written.

The timing controller 20 rearranges the digital video data of the input image input from the host system 40 to the data driving circuit 12 in accordance with the pixel arrangement of the display panel. The timing controller 20 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 40. In response, the operation timings of the data driver circuit 12 and the scan driver 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 40 may be implemented as any one of a television system, a set top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, and a phone system. The host system 40 includes a system on chip (SoC) having a built-in scaler to convert digital video data RGB of an input image into a format suitable for displaying on the display panel DIS. The host system 40 transmits timing signals Vsync, Hsync, DE, and MCLK together with the digital video data to the timing controller 20. In addition, the host system 40 executes an application program associated with the coordinate information XY of the touch data input from the algorithm execution unit 36.

The touch screen TSP includes Tx lines (Tx1 to TxN, N is a positive integer), Rx lines (Rx1 to RxM, M is a positive integer) and Tx lines intersecting the Tx lines (Tx1 to TxN). MxN touch sensors Cm formed at intersections of the lines Tx1 to TxN and the Rx lines Rx1 to RxM. Each of the touch sensors Cm includes a mutual capacitance.

The touch screen driving circuit includes a touch sensing circuit 30 and an algorithm execution unit 36. The touch screen driving circuit senses a voltage change of the touch sensors by supplying a driving signal to the touch screen TSP and transmits coordinate information of the touch input position to the host system 40.

The touch sensing circuit 30 includes a Tx driving circuit 32, an Rx driving circuit 34, a Tx / Rx controller 38, and the like.

The touch sensing circuit 30 applies a driving signal to the touch sensors through the Tx lines Tx1 to TxN using the Tx driving circuit 32 and synchronizes the Rx lines Rx1 to RxM with the driving signal. The voltage of the touch sensors Cm is sensed through the Rx driving circuit 34 to output touch raw data, which is digital data. The Tx / Rx controller 38 controls one or more of the width, number, and voltage of the driving signals in proportion to the RC delay of the touch screen TSP. The driving signal is generated in the form as shown in FIGS. 12 to 17 in consideration of the RC delay difference of the touch screen TSP. The driving signal is controlled in one or more of the width, number, and voltage in proportion to the RC delay to uniformize the charging characteristics in all the touch sensors Cm of the touch screen TSP. The touch sensing circuit 30 may be integrated into one ROIC. The touch sensing circuit 30 and the algorithm execution unit 36 may be integrated into one touch IC.

The Tx driving circuit 32 selects a Tx channel for outputting a driving signal in response to the Tx setup signal from the Tx / Rx controller 38, and the Tx lines 12x to Tx lines Tx1 to TxN connected to the selected Tx channel. The same drive signal as 17 is applied. The Tx lines Tx1 to TxN are charged during the high potential period of the driving signal to supply electric charges to the touch sensors Cm, and are discharged in the low potential period of the driving signal. The driving signal is N (where N is 2 or more) to the capacitor (FIG. 8, Cs) of the integrator in which the voltages of the touch sensors Cm are built in the Rx driving circuit 34 through the Rx lines Rx1 to RxM. N times may be continuously supplied to each of the Tx lines Tx1 to TxN so as to accumulate a positive integer).

The Rx driving circuit 34 selects Rx lines to receive the voltage of the touch sensor in response to the Rx setup signal from the Tx / Rx controller 38, and then touches the touch sensor Cm through the selected Rx lines in synchronization with the driving signal. Receive and sample the output voltage of. The Rx driving circuit 34 accumulates the voltage received from the touch sensor in the capacitor Cs of the integrator as shown in FIG. 8 and converts the voltage through an analog-to-digital converter (hereinafter referred to as "ADC"). Convert raw data to output touch raw data. When the touch sensor is touched, the capacitance value C becomes small at Q (charge) = C (capacity) x V (voltage). Therefore, since the charge change amount of the touch sensor Cm in which the touch input is generated is larger than that of the touch sensor without the touch input, presence or absence of the touch input may be determined based on the difference in the charge change amount.

The Rx driving circuit 34 converts the charge change amount before and after the touch into the touch raw data, which is digital data, through the ADC and supplies it to the algorithm execution unit 36. 8 and 9, "Vd" is the voltage of the drive signal. "OP" is the op amp of the integrator. "11" is an example waveform in which the voltage of the touch sensor is accumulated in the integrator before the touch, and "12" is an example waveform in which the voltage of the touch sensor is accumulated in the integrator after the touch.

The Tx / Rx controller 38 controls the Tx channel and Rx channel settings in response to the Tx setup signal and the Rx setup signal from the algorithm execution unit 36 and synchronizes the Tx driver 32 and the Rx driver 34. In addition, the Tx / Rx controller 38 controls the driving signal by generating a modulation signal so that the driving signal may be modulated in width, number, voltage, etc. in proportion to the RC delay of the touch screen TSP.

The algorithm execution unit 36 executes a preset touch recognition algorithm and compares the touch raw data received from the Rx driver circuit 34 with a preset threshold. Any known algorithm may be used as the touch recognition algorithm. The touch recognition algorithm detects touch raw data above a threshold. The touch raw data above the threshold is determined as touch data obtained from touch sensors in which a touch input is generated. The algorithm execution unit 36 executes a touch recognition algorithm, assigns an identification number to each of the touch data having a threshold value or more, and calculates coordinates. The algorithm execution unit 36 transmits the identification number and the coordinate information of each of the touch data having a threshold value or more to the host system 40. The algorithm execution unit 36 may be implemented as a micro controller unit (MCU).

The touch sensing circuit 30 is generally disposed at a position close to one side of the touch screen TSP as shown in FIG. 12. As illustrated in FIG. 12, when the touch sensing circuit 30 and the touch screen TSP are connected, the RC delay of the touch screen TSP increases as the distance from the touch sensing circuit 30 increases. The touch sensing system of the present invention controls the width of the driving signal in proportion to the RC delay of the touch screen TSP as shown in FIGS. 11 and 12 in consideration of the RC delay that varies depending on the position of the touch screen TSP.

11 and 12, the touch screen TSP may be divided into a plurality of blocks B1 to B3. Each of the blocks B1 to B3 includes two or more Tx lines to which a driving signal is applied. 11 illustrates an example in which the touch screen TSP is divided into three blocks B2 to B3, but the number of block divisions is not limited to three.

The RC delay of the first block B1 is smaller than the other blocks B2 and B3 because it is close to the touch sensing circuit 30. On the other hand, the RC delay of the third block B3 is largest because it is far from the touch sensing circuit 30. The RC delay of the second block B2 is larger than the first block B1 and smaller than the third block B3. This block-by-block RC delay difference results in a difference in charging characteristics of the touch sensors Cm. For example, the touch sensor Cm formed at a position where the RC delay is small has a large amount of charging, whereas the touch sensor Cm formed at a position where the RC delay is large is a small amount of charging.

When the touch screen TSP divides and drives the plurality of blocks B1 to B3, the driving signals applied to the Tx lines belonging to the same block have the same width. In contrast, the width of the driving signal is different between the blocks.

When the touch screen TSP divides and drives the blocks B1 to B3, the driving signals applied to the blocks B1 to B3 have a width W1 to W3 proportional to the RC delay as shown in FIG. 12. . For example, the width W1 of the driving signal applied to the Tx lines of the first block B1 having a small RC delay is set smaller than the other blocks B2 and B3. The width W3 of the driving signal applied to the Tx lines of the third block B3 having a large RC delay is set larger than the other blocks B1 and B2. The width W2 of the drive signal applied to the Tx lines of the second block B2 is set larger than that W1 of the first block B1 and smaller than that W3 of the third block B3. do.

If the touch screen TSP is divided into a plurality of blocks B1 to B3 and the driving signal is increased only in a block having a large RC delay, there is no increase in sensing time. Therefore, the present invention can speed up the touch report rate.

As shown in FIG. 12, the width W1 to W3 may be set differently for each block, but is not limited thereto. For example, the width of the driving signal is the smallest in the first Tx line Tx1 and gradually increases toward the Nth Tx line TxN in proportion to the RC delay.

FIG. 13 shows a driving signal applied to a touch sensor having a large RC delay in comparison with the prior art and the present invention.

Referring to FIG. 13, the prior art applies the driving signal of the same width to the touch sensors Cm (the upper figure of FIG. 13) without considering the RC delay of the touch screen TSP. As a result, according to the prior art, the charge amount ΔQ of the touch sensor Cm with a large RC delay is small.

In contrast, the present invention controls the width of the driving signal applied to the touch sensor Cm having a large RC delay as shown in FIG. 12. As a result, the present invention controls the duration of the driving voltage Vd applied to the touch sensor Cm having a large RC delay to be longer, so that the charge amount ΔQ of the touch sensor Cm is as much as a touch sensor having a small RC delay. It can increase.

14 shows an example of a drive signal generator according to an embodiment of the present invention. FIG. 15 is a waveform diagram illustrating input and output signals of the driving signal generator shown in FIG. 14. The driving signal generator may be built in the Tx driving circuit 32.

14 and 15, the driving signal generator may be implemented as a pulse width modulation (PWM) circuit. The PWM circuit can be simply implemented as a comparator (COMP). A modulating signal and saw-tooth wave are input to the comparator COMP. The comparator COMP generates a high potential output when the voltage of the modulation signal is greater than the voltage of the sawtooth signal, and generates a driving signal whose widths W1 to W3 vary according to the voltage level of the modulation signal. Accordingly, the touch sensing system of the present invention may generate a driving signal having a width proportional to the RC delay by increasing the voltage of the modulation signal as the RC delay of the touch screen TSP increases.

16 and 17 are waveform diagrams showing driving signals according to another embodiment of the present invention.

The touch sensing system of the present invention may control the number of driving signals in proportion to the RC delay of the touch screen (TSP) as shown in FIG. 16. In this case, the touch sensor Cm having a large RC delay in the touch screen TSP increases the number of driving signals applied at the same time as the touch sensor having a small RC delay. As the number of driving signals increases, the charging amount of the touch sensors Cm also increases. The touch sensing system of the present invention may generate a driving signal as shown in FIG. 16 by using a pulse frequency modulation (PFM) circuit or a pulse position modulation (PPM).

The touch sensing system of the present invention may control the voltages V1 to V3 of the driving signal in proportion to the RC delay of the touch screen TSP as shown in FIG. 17. In this case, a driving signal of a higher voltage is applied to the touch sensor Cm having a large RC delay in the touch screen TSP as compared to a touch sensor having a small RC delay. The higher the voltage of the driving signal, the greater the amount of charge of the touch sensors Cm. The touch sensing system of the present invention may generate a driving signal as shown in FIG. 17 by using a pulse amplitude modulation (PAM) circuit.

The driving signals shown in FIGS. 16 and 17 may be controlled for each block as shown in FIGS. 11 and 12. The touch sensing system of the present invention may compensate for the RC delay by combining the characteristics of the driving signals illustrated in FIGS. 12, 13, and 14. For example, the touch sensing system of the present invention may control two or more of the width, number, and voltage of the driving signal in proportion to the RC delay of the TSP.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical 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 defined by the claims.

DIS: Display panel TSP: Touch screen
12: data driving circuit 14: scan driving circuit
20: timing controller 30: touch sensing circuit
32: Tx driving circuit 34: Rx driving circuit
36: algorithm execution unit

Claims (6)

A touch screen including touch sensors; And
A touch sensing circuit applying a driving signal to the touch sensors;
At least one of the width, number, and voltage of the driving signal is controlled in proportion to the RC delay of the touch screen,
The touch screen is divided into a plurality of blocks,
Each of the blocks includes two or more lines to which the driving signal is applied;
The width, number and voltage of the driving signals are the same in one block,
Touch sensing system, characterized in that one or more of the width, number, voltage of the driving signal between the blocks. delete The method of claim 1,
And a width of the driving signal increases in proportion to the RC delay of the touch screen. The method of claim 1,
And a number of the driving signals increases in proportion to the RC delay of the touch screen. The method of claim 1,
And a voltage of the driving signal is increased in proportion to the RC delay of the touch screen. A driving method of a touch sensing system including a touch screen including touch sensors and a touch sensing circuit applying a driving signal to the touch sensors,
Controlling at least one of the width, number, and voltage of the driving signal in proportion to the RC delay of the touch screen;
The touch screen is divided into a plurality of blocks,
Each of the blocks includes two or more lines to which the driving signal is applied;
The width, number and voltage of the driving signals are the same in one block,
And at least one of a width, a number, and a voltage of the driving signal is different between the blocks.

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