KR101764714B1 - Method for compensation of differential offset based on voltage shifting and its apparatus system for touch screen sensing - Google Patents

Abstract

Disclosed are a method to compensate for a differential offset based on a voltage shaft and a touch screen system using the same. The method includes: a step in which an output offset compensation circuit determines a plurality of differential offset voltages in a touch screen operated in an offset storage mode to compensate for an output voltage offset for a plurality of RX lines; a step in which the touch screen receives a touch signal as an input signal; and a step in which the output offset compensation circuit compensates for at least one output offset for at least one RX line, which is matched with the touch signal, in the touch screen operated in a normal operation mode based on at least one differential offset voltage which is matched with the RX line.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential offset compensating method and a touch screen system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch screen system, and more particularly, to a differential offset compensation method based on voltage shift in a touch screen and a touch screen system using such a method.

Recently, with the development of smart phones, products equipped with touch screens are rapidly increasing. In addition to smartphones, the application of touch screens to notebooks, desktops, all-in-one personal computers, advertising display boards, televisions, and electronic blackboards is also increasing rapidly. Market research also predicts that the size of the large touch screen industry will continue to grow. The driving method of the touch screen is largely divided into the resistance film type and the capacitive type touch screen depending on the type and shape of the electrode. The most commonly used method is a capacitive touch screen, which detects the change in the capacitance value of an electrode when a human body (a finger, etc.) changes instead of the pressure applied to the transparent electrode plate, and calculates the touched position. The capacitance type is divided into the self capacitance type and the mutual capacitance type. In the self capacitance type, the self capacitance of each transparent electrode intersection line is changed when the touch is generated, and the touch position is detected by sensing the capacitance. The mutual capacitance method detects the mutual electrostatic capacitance variation between two transparent electrode intersecting lines of both sides and finds the positions of several human touch points at the same time, and is the most widely used method in current smart phones. A touch sensor is usually made of an ITO (Indium Tin Oxide) film or a metal mesh film. Various types of electrode patterns are formed on a transparent film. An input waveform is driven through some electrodes and each output electrode is sequentially To judge whether or not the touch is made.

KR 10-2009-0111027

One aspect of the present invention provides a differential offset compensation method based on voltage shift in a touch screen.

Another aspect of the present invention provides a touch screen system using a differential offset compensation method based on voltage shift in a touch screen.

A method of compensating differential offset based on a voltage shift in a touch screen according to an aspect of the present invention is characterized in that in the touch screen operating in an offset storage mode, an output offset compensation circuit adjusts an output voltage offset for each of a plurality of RX Wherein each of the plurality of RX lines includes a plurality of differential offset voltages, the touch screen receiving input of a touch signal as an input signal, and the touch screen operating in a normal operation mode, Compensating at least one output offset for at least one RX line corresponding to the touch signal based on at least one differential offset voltage corresponding to the at least one RX line of the plurality of differential offset voltages .

On the other hand, the step of determining each of the plurality of differential offset voltages comprises the steps of the output offset compensation circuit receiving each of a plurality of differential output voltages in a touched state for the plurality of RX lines, converting each of the plurality of differential output voltages to a digital value based on an analog to digital converter (ADC), the output offset compensation circuit including a plurality of differential output voltages for each of the plurality of RX lines, Offset voltage, and the output offset compensation circuit may store each of the plurality of differential offset voltages for each of the plurality of RX lines in an offset memory.

Compensating for the at least one output offset based on the at least one differential offset voltage corresponding to the at least one RX line of the plurality of differential offset voltages is characterized in that the output offset compensation circuit comprises: Shifting the at least one differential offset voltage corresponding to the line in each of the two voltage-shifting capacitors, and the output offset compensating circuit is operable to cause each of the at least one output offset based on the two voltage- And compensating for each of the output offsets by shifting the differential offset voltage to each.

Also, the step of inputting the touch signal as the input signal on the touch screen may include the steps of: RX_PASS of the crossing switch of the touch screen is activated to output a positive spike waveform of the at least one RX line; RX_CROSS of the crossing switch is activated to output a negative spike waveform of the at least one RX line and inputting the positive spike waveform and the negative spike waveform into the touch signal.

In the normal operation mode, the reset state and the integration state are repeatedly executed. In the reset state, the reset capacitor is reset to 0 V, and the offset offset voltage for the RX line to be sensed among the plurality of RX lines in the offset memory is set to And a differential output voltage including an output offset to the RX line is output, wherein the differential output voltage is stored in a voltage shifting capacitor, and in the integrated state, a driving signal is sequentially applied to a TX (transmit) The output offset can be eliminated by the differential offset voltage.
Also, in the normal operation mode, the operation sequence of the integrator and the output offset compensation circuit is set to a reset state in which RX_INT_EN is set to 0 and CAL_TRANS is set to 1, an integration state in which RX_INT_EN is set to 1, and CAL_TRANS is set to 0 Executing; In the reset state, the integrator resets C _INT to 0 V, and the offset compensation circuit reads the offset value stored in the offset memory using the address corresponding to the next RX line to be sensed and converts the offset value into the differential offset voltage using the DAC Shifting the output voltage of the integrator inversely as much as the differential offset voltage by storing the differential offset voltage values in each of the two voltage shifting capacitors C _SHIFTER ; And the step of operating the integrator and the offset compensating circuit in the integrated state sequentially apply driving signals to the TX line and integrate and output the differential signals of two adjacent RX lines using the integrator and then output the differential output voltage of the integrator Shifting the offset value stored in the voltage shifting capacitor C _SHIFTER to generate an ideal integrator output value, and converting the offset value to a digital value using the ADC.

According to another aspect of the present invention, there is provided a touch screen system for performing differential offset compensation based on voltage shift, including an input unit for receiving a touch signal as an input signal and a plurality of RX (receive) lines For each of a plurality of RX lines corresponding to the touch signal among the plurality of RX lines in the touch screen operating in a normal operation mode and for determining a plurality of differential offset voltages for compensating for an output voltage offset for each of the at least one To compensate the output offset of the plurality of differential offset voltages based on at least one differential offset voltage corresponding to the at least one RX line of the plurality of differential offset voltages.

On the other hand, the output offset compensation circuit receives each of the plurality of differential output voltages in a non-touched state with respect to the plurality of RX lines, and outputs each of the plurality of differential output voltages as a digital value based on an analog to digital converter Determining each of the plurality of differential output voltages as the plurality of differential offset voltages for each of the plurality of RX lines and storing each of the plurality of differential offset voltages for each of the plurality of RX lines in an offset memory . ≪ / RTI >

The output offset compensation circuit may also store the at least one differential offset voltage corresponding to the at least one RX line, each of the two voltage shifting capacitors, and the at least one output offset based on the two voltage shifting capacitors, To each of the at least one differential offset voltage to compensate for each of the output offsets.

Also, the input activates RX_PASS of the crossing switch to output a positive spike waveform of the at least one RX line, activates RX_CROSS of the crossing switch to output a negative spike waveform of the at least one RX line, The positive spike waveform and the negative spike waveform may be input as the touch signal.

In the normal operation mode, the reset state and the integration state are repeatedly executed. In the reset state, the reset capacitor is reset to 0 V, and the offset offset voltage for the RX line to be sensed among the plurality of RX lines in the offset memory is set to And outputting a differential output voltage including an output offset to the RX line, wherein the differential output voltage is stored in a voltage-shifting capacitor, and in the integrated state, a driving signal is sequentially applied to a TX (transmit) The output offset can be removed by the differential offset voltage.

A differential offset compensation method based on voltage shift in a touch screen according to an embodiment of the present invention and a touch screen system using such a method are generated by a mismatch between a sensing circuit of an existing touch screen and an input / It is possible to remove the offset and increase the signal-to-noise ratio (SNR) according to the presence or absence of noise compared to the noise, and to greatly improve the performance of the touch detection. Therefore, not only the improvement of the performance of the touch screen for a smartphone, but also the touch sensing device of a large touch screen are advantageous, and the multi touch process is also advantageous.

1 is a conceptual diagram illustrating a differential sensing method in a conventional touch screen.
2 is a conceptual diagram illustrating a differential offset compensation method based on voltage shift in a touch screen according to an exemplary embodiment of the present invention.
3 is a conceptual diagram illustrating a timing diagram of a touch sensing circuit using an output offset compensation circuit according to an embodiment of the present invention.
4 is a flowchart illustrating a method of sensing a touch signal based on an output offset compensation method according to an embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

1 is a conceptual diagram illustrating a differential sensing method in a conventional touch screen.

1, a sensing method for a differential RX line (differential receive line) of a conventional touch screen controller is disclosed.

In the differential sensing method, a square wave (square wave) is applied through a TX line (transmit line) 100 of a touch screen panel, an output waveform is read from an RX line 120 on the right side of the touch screen panel, Can be switched to a voltage.

The problems of the conventional touch screen controller method are as follows.

The touch state can be determined by applying a square wave to the TX line 100 and then comparing the waveform of the signal on the RX line 120. [ For example, if the RX line of one of the two RX lines is touched, a smaller spike waveform may be measured in the touched RX line. Conversely, when two RX lines are both in a touch or non-touch state, a spike waveform of approximately the same magnitude can be measured on two RX lines.

The accumulated voltage may be output by applying the spike waveforms generated on the two RX lines to the differential integrator 150 in order to discriminate the presence or absence of the touch. The integrator can accumulate a small amount of charge on a capacitor to convert it to a voltage of a level that can be sensed. At this time, when both RX lines are in a touch state or a non-touch state, a signal having the same waveform is applied across the integrator input. Therefore, the two output terminal voltages cancel each other and the same value can be output.

Conversely, when one RX line is in a touch state, different spike waveforms are applied to both inputs, and the values of the different spike waveforms can be integrated by the integrator. At this time, the positive output is integrated with a value larger than the common voltage, and the negative output is integrated with the smaller value to decrease. Due to the mismatch of the elements of the actual implemented circuit, the integrator may have an offset voltage at the input and output. Even if the input voltages of the differential integrators are equal to each other due to the offset voltage, a problem that a different value is output to two output terminals occurs very frequently.

The offset voltage also has a problem that even when only one input terminal RX line is touched, the offset voltage has an increase or decrease width that is larger than an expected output value of the integrator. When the increase or decrease of the output value of the integrator exceeds the maximum allowable output due to the offset voltage, the touch sensing performance of the touch screen may be greatly deteriorated due to the inconvenient result that the touch state can not be discriminated.

A multi-touch control method and system for detecting a touched position of a finger on a capacitive touch screen for preventing deterioration of the touch sensing performance of the touch screen due to the offset voltage are disclosed herein.

In the differential offset compensation method based on the voltage shift in the touch screen according to the embodiment of the present invention and the touch screen using this method, the offset voltage of the integrator is removed to keep the integrator output value not exceeding the allowable value, the signal to noise ratio (SNR) of the touch screen can be more accurately determined.

2 is a conceptual diagram illustrating a differential offset compensation method based on voltage shift in a touch screen according to an exemplary embodiment of the present invention.

In Fig. 2, a differential offset compensation circuit (or an output offset correction circuit) for compensating a voltage offset based on a voltage shift is disclosed.

The touch sensing circuit for sensing a touch on the touch screen may include a crossing switch 210, a differential integrator, and an output offset compensation circuit using voltage shifting.

The output offset compensation circuit includes an output offset measurement analog to digital converter (ADC) 200, an output offset storage memory 220, an output offset conversion DAC 240, and an output offset voltage shifting capacitor 260 .

The output offset compensation circuit can compensate the output offset in the following manner.

One TX line is selected on the touch screen and a TX signal excitation driver can supply a square wave pulse signal over the repeatedly selected TX line. At this time, two two adjacent RX lines are simultaneously selected and the sensing circuit can be operated. Once detection is completed for all adjacent RX lines, one next TX line can be selected and the detection procedure for all adjacent RX lines can be repeated. When all the TX lines are selected in this manner, the touch detection for one frame of the touch screen is completed, and the above process can be continuously repeated for detecting the next frame.

The operation of the touch sensing circuit for differential offset compensation based on the voltage shift according to the embodiment of the present invention is as follows.

The crossing switch 210 of the touch sensing circuit according to the embodiment of the present invention can simultaneously receive a sensing signal output through two adjacent RX lines selected on the touch screen. The crossing switch may include an RX_PASS switch and an RX_CROSS switch, and the input to the integrator may be determined based on the switching of each of the RX_PASS switch and the RX_CROSS switch.

Specifically, when the RX_PASS switch of the crossing switch 210 is activated, the even-numbered RX line signal of the touch screen is connected to the positive input of the integrator and the odd-numbered RX line signal is input to the negative input of the integrator .

Conversely, when the RX_CROSS switch of the crossing switch 210 is activated, the signal of the even-numbered RX line may be connected to the negative input of the integrator, and the signal of the odd-numbered RX line may be connected to the positive input. In this way, the positive or negative spike waveform of each of the RX lines can be integrated to determine whether the touch is present or not.

Therefore, the crossing switch can be controlled by synchronizing the two spike waveforms for the presence / absence of touch. RX_PASS of the crossing switch 210 is activated and RX_CROSS is activated for output of the negative spike waveform of the RX lines for output of the positive spike waveform of the RX lines.

The operation of the differential integrator of the touch sensing circuit according to the embodiment of the present invention is as follows.

When two spike waveforms are applied to the positive input and the negative input of the differential integrator, the differential integrator can integrate the difference between the two inputs and store the integrated value in the two feedback capacitors, C _INT . When the input waveform is supplied for a predetermined number of integrations and integration for all input waveforms is completed, the two values stored in C _INT can be transferred to the next stage as the differential output voltage. If the two selected RX lines are all in the same state (all touched or not touched), 0V is expected as the differential input, and the differential output after integration is also expected to be 0V. Conversely, if one RX line is in the touch state, the voltage difference of the differential input occurs and can be integral so that the differential output can have a positive or negative voltage. At this time, when the differential output is positive, the odd-numbered RX line (positive input side) can be discriminated as the touch state when the even-numbered RX line (negative input side) is in the touch state and the differential output is negative.

However, in a circuit implemented in a semiconductor, an output offset is often generated at the integrator output by mismatching the input stage, the integrator, or the output stage, and the generated output offset may cause an error in the differential output voltage. If the input waveforms are in the same state, a high differential output voltage can be generated due to the error, and a large output offset can also cause an error that reverses the negative positive number of the differential output. Thus, this output offset can be corrected by the output offset compensation circuit.

The operation of the output offset compensation circuit of the touch sensing circuit for compensating the output offset is as follows. To compensate for the output offset, the touch screen sensing circuit can be set to the offset storage mode intermittently, and measurement and storage of the output offset can be performed. In the offset storage mode, all TX lines are not driven and all RX lines can be output without being touched. An output offset value for each of a plurality of RX lines included in the touch screen can be measured.

The differential output voltage of the integrator for one RX line is applied to an analog to digital converter (ADC) 200 and the ADC 200 can convert the differential output voltage to a digital value. In an ideal case without an output offset, the differential output may be 0V. If an output offset is present, the output offset value can be converted to a digital value. The output offset value converted into the digital value may be stored in the address of the offset memory 220 corresponding to the currently sensed RX line of the offset memory 220 and corresponding to the currently sensed RX line.

When measurement and storage of the output offset for all RX lines is complete, the offset storage mode is terminated and the touch screen touch circuit can be set to the normal operation mode.

In normal operating mode, the integrator and the output offset compensation circuit can be executed by repeating the reset state (RX_INT_EN = 0, CAL_TRANS = 1) and the integral state (RX_INT_EN = 1, CAL_TRANS = 0).

In the reset state, the integrator resets C _INT to 0 V, and the offset compensation circuit reads the offset value stored in the offset memory 220 using the address corresponding to the next RX line to be sensed, It can be converted into an offset voltage. At this time, the differential offset voltage values are stored in two voltage shifting capacitors C _SHIFTER 260, respectively, so that the output voltage of the integrator can be reversed by the differential offset voltage to eliminate the influence of the output offset present in the output voltage.

In the integrated state, a driving signal can be sequentially applied to the TX line. The integrator can integrate and output the differential signal of the adjacent RX lines. After the completion of the integration, the integrator differential output voltage can have the same values as the ideal integrator and the ideal input / output circuit without offset.

3 is a conceptual diagram illustrating a timing diagram of a touch sensing circuit using an output offset compensation circuit according to an embodiment of the present invention.

Referring to FIG. 3, a TX input signal 300 represents a square wave signal applied to a TX line.

TX output signal 310 represents a positive spike signal, a negative spike signal output from the RX line,

The RX_PASS signal 320 and the RX_CROSS signal 330 are signals for controlling the switching operation of the RX_PASS switch and the RX_CROSS switch of the crossing switch.

The SAMPLE signal 340 is a signal for storing the digitally converted offset value output from the ADC.

The AMP_RST signal 350 is a signal for discharging the feedback capacitor of the differential integrator.

The CAL_TRANS signal 360 and the RX_INT_EN signal 370 are non-overlapping signals that do not overlap with each other, and when the CAL_TRANS signal 360 is activated, the differential offset voltage converted into an analog value by the DAC in the capacitor can be set . The RX_INT_EN signal 370 is a drive signal for operating the differential integrator and may shift the output voltage of the differential integrator output by the RX_INT_EN signal 370 as much as the differential offset voltage to eliminate the effect of the output offset present in the output voltage have.

Therefore, when the offset compensation circuit of the present invention is applied, the offset of the integrator and the input / output circuit can be precisely removed, and the presence or absence of the touch on the RX line can be measured as an accurate integrator differential output value.

4 is a flowchart illustrating a method of sensing a touch signal based on an output offset compensation method according to an embodiment of the present invention.

4, a method of measuring a value of an output offset and detecting a touch signal through an offset compensation operation through an offset compensation circuit when the output offset value becomes equal to or larger than a threshold value is disclosed.

4, in a touch screen operating in an offset storage mode, an output offset compensation circuit may determine each of a plurality of differential offset voltages for compensating for an output voltage offset for each of a plurality of RX (receive) lines ).

To determine each of the plurality of differential offset voltages, an output offset compensation circuit may receive each of the plurality of differential output voltages in a non-touched state for a plurality of RX lines. The output offset compensation circuit may then convert each of the plurality of differential output voltages to a digital value based on an analog to digital converter (ADC). The output offset compensation circuit may also determine each of the plurality of differential output voltages as a plurality of differential offset voltages for each of the plurality of RX lines. The output offset compensation circuit may store each of the plurality of differential offset voltages for each of the plurality of RX lines in an offset memory.

The touch screen can receive a touch signal as an input signal (step S410).

After the differential offset voltage for compensating the output voltage offset is determined in the offset storage mode, the input signal of the user can be inputted through the touch screen.

Specifically, when a touch signal is input as an input signal on a touch screen, RX_PASS of the crossing switch of the touch screen is activated to output a positive spike waveform of at least one RX line, and RX_CROSS of the crossing switch of the touch screen is activated A step of outputting a negative spike waveform of at least one RX line and a step of inputting a positive spike waveform and a negative spike waveform as a touch signal.

The output offset compensation circuit in the touch screen operating in the normal operation mode is adapted to output at least one output offset for at least one RX line corresponding to the touch signal among the plurality of RX lines to at least one RX line of the plurality of differential offset voltages (Step < RTI ID = 0.0 > S420). ≪ / RTI >

Specifically, the output offset compensation circuit may store at least one differential offset voltage corresponding to at least one RX line, each of the two voltage-shifting capacitors. The output offset compensation circuit may compensate each of the output offsets by shifting each of the at least one output offset based on the two voltage shifting capacitors to each of the at least one differential offset voltage.

Such differential offset compensation based on voltage shifts in a touch screen may be implemented in an application or implemented in the form of program instructions that can be executed through various computer components and recorded on a computer readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination.

The program instructions recorded on the computer-readable recording medium may be ones that are specially designed and configured for the present invention and are known and available to those skilled in the art of computer software.

Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules for performing the processing according to the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (10)

A differential offset compensation method based on voltage shift in a touch screen,
Determining, in the touch screen operating in an offset storage mode, an output offset compensation circuit, each of the plurality of differential offset voltages for compensating an output voltage offset for each of a plurality of receive lines;
Receiving a touch signal as an input signal from the touch screen; And
In the touch screen operating in the normal operation mode, the output offset compensation circuit outputs at least one output offset for at least one RX line corresponding to the touch signal among the plurality of RX lines to the at least one of the plurality of differential offset voltages Compensating based on at least one differential offset voltage corresponding to one RX line,
Compensating the at least one output offset based on the at least one differential offset voltage corresponding to the at least one RX line of the plurality of differential offset voltages,
The output offset compensation circuitry storing the at least one differential offset voltage corresponding to the at least one RX line in each of the two voltage shifting capacitors; And
And shifting each of the at least one output offset to each of the at least one differential offset voltage based on the two voltage-shifting capacitors to compensate each of the output offsets by the output offset compensation circuit Way. The method according to claim 1,
Wherein determining each of the plurality of differential offset voltages comprises:
The output offset compensation circuit receiving each of the plurality of differential output voltages in a non-touch state for the plurality of RX lines;
Converting each of the plurality of differential output voltages into a digital value based on an analog to digital converter (ADC);
The output offset compensation circuitry determining each of the plurality of differential output voltages as each of the plurality of differential offset voltages for each of the plurality of RX lines; And
Wherein the output offset compensation circuit includes storing each of the plurality of differential offset voltages for each of the plurality of RX lines in an offset memory. The method according to claim 1,
In the normal operation mode, the operation sequence of the integrator and the output offset compensation circuit is such that the reset state in which RX_INT_EN is set to 0 and CAL_TRANS is set to 1, and the integration state in which RX_INT_EN is set to 1 and CAL_TRANS is set to 0 are repeated step;
In the reset state, the integrator resets C _INT to 0 V, and the offset compensation circuit reads the offset value stored in the offset memory using the address corresponding to the next RX line to be sensed and converts the offset value into the differential offset voltage using the DAC Shifting the output voltage of the integrator inversely as much as the differential offset voltage by storing the differential offset voltage values in each of the two voltage shifting capacitors C _SHIFTER ; And
The operation step of the integrator and the offset compensating circuit in the integrated state sequentially applies the driving signal to the TX line and integrates and outputs the differential signals of two adjacent RX lines using the integrator and then outputs the differential voltage Shifting the offset value stored in the shifting capacitor C _SHIFTER to produce an ideal integrator output value, and then converting the offset value to a digital value using the ADC. The method according to claim 1,
Wherein the step of inputting the touch signal as the input signal on the touch screen comprises:
Wherein RX_PASS of the crossing switch in the touch screen is activated to output a positive spike waveform of the at least one RX line;
Wherein RX_CROSS of the crossing switch is activated on the touch screen to output a negative spike waveform of the at least one RX line; And
Wherein the positive spike waveform and the negative spike waveform are input as the touch signal. The method according to claim 1,
Wherein the normal operation mode repeatedly executes the reset state and the integral state,
Resetting the initializing capacitor to 0 V in the reset state, storing a differential offset voltage for the RX line to be sensed among the plurality of RX lines in the offset memory in a shifting capacitor,
And outputting a differential output voltage including an output offset to the RX line, wherein the driving signal is sequentially applied to a TX (transmit) line in the integrated state,
And the output offset is removed by the differential offset voltage at the differential output voltage. A touch screen system for performing differential offset compensation based on voltage shift,
An input unit for receiving a touch signal as an input signal; And
Determining a plurality of differential offset voltages for compensating for an output voltage offset for each of a plurality of RX (receive) lines in the touch screen operating in an offset storage mode, At least one output offset for at least one RX line corresponding to the touch signal in the line is compensated based on at least one differential offset voltage corresponding to the at least one RX line of the plurality of differential offset voltages And an output offset compensation circuit,
Wherein the output offset compensation circuit comprises:
Shifting the at least one differential offset voltage corresponding to the at least one RX line into two voltage-shifting capacitors,
And to compensate each of the output offsets by shifting each of the at least one output offset to each of the at least one differential offset voltage based on the two voltage shifting capacitors. The method according to claim 6,
The output offset compensation circuit receives each of the plurality of differential output voltages in a non-touch state for the plurality of RX lines,
Converting each of the plurality of differential output voltages into a digital value based on an analog to digital converter (ADC)
Each of the plurality of differential output voltages is determined as each of the plurality of differential offset voltages for each of the plurality of RX lines,
And store each of the plurality of differential offset voltages for each of the plurality of RX lines in an offset memory. delete The method according to claim 6,
Wherein the input activates RX_PASS of the crossing switch to output a positive spike waveform of the at least one RX line and activates RX_CROSS of the crossing switch to output a negative spike waveform of the at least one RX line, And the spike waveform and the negative spike waveform are input as the touch signal. The method according to claim 6,
Wherein the normal operation mode repeatedly executes the reset state and the integral state,
Resetting the initializing capacitor to 0V in the reset state, storing a differential offset voltage for the RX line to be sensed among the plurality of RX lines in the offset memory in the voltage shifting capacitor,
Sequentially applying a driving signal to a transmit (TX) line in the integrated state and outputting a differential output voltage including an output offset to the RX line,
And removes the output offset by the differential offset voltage at the differential output voltage.

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