KR20190020953A - Touch screen - Google Patents

Abstract

The present invention relates to a touch screen. According to an embodiment of the present invention, the touch screen comprises: a plurality of touch sensors arranged in a matrix of a plurality of rows and columns; a plurality of sensor signal lines connected to the touch sensors; and a touch drive IC receiving touch signals generated in the touch sensors. The touch drive IC includes an analog front end circuit, a DC/DC converter, and a logic unit. The logic unit may synchronize a switching pulse signal applied to the DC/DC converter to regularly detect noise due to the switching pulse signal based on a drive pulse signal applied to the analog front end circuit. In addition, the present invention includes embodiments other than the described embodiment.

Description

Touch screen {Touch screen}

The present invention relates to, for example, a touch screen for eliminating power source noise.

Generally, the touch screen is a mobile device such as a navigation device, a netbook, a notebook, a DID (Digital Information Device), and an IPTV (Internet Protocol TV) as well as a mobile device such as a smart phone, a PDA (Personal Digital Assistants) And the like.

The touch screen includes an on-cell type touch screen added to various types of displays such as a liquid crystal display (LCD), a plasma display panel (PDP), and an organic light emitting diode (OLED) And an in-cell type touch screen which is built in as a unit.

The display to which the touch screen is applied may be variously classified into an add-on type display, a touch screen on-cell type display, and a touch screen built-in type display .

The touch screen may be applied to various types of touch detection methods such as a resistive type, a capacitive type, an electromagnetic induction type, an infrared type, and an ultrasonic type.

The capacitance type touch screen has a touch input device such as a finger or an electronic pen that touches or approaches a touch sensor arranged on the touch screen so that the touch capacitance generated by the touch sensor, touch and touch position can be detected based on the voltage change by touch capacitance.

1 is a diagram illustrating a configuration of a general touch screen.

Referring to FIG. 1, the touch screen 100 may be, for example, a capacitive touch screen, and may include a plurality of touch sensors 10, a plurality of sensor signal lines 11, (TDI: Touch Drive IC) 30, and the like.

The touch sensors 10 may be arranged in a matrix of a plurality of rows and columns and may be variously called various other names such as a touch pad, Can be.

The sensor signal lines 11 may be connected to the touch sensors 10 and may transmit the touch capacitance Ct generated by the touch sensors to the touch driver IC 30. [

The touch driver IC 30 drives the touch sensors 10 and receives a touch capacitance Ct generated in the touch sensors through the sensor signal lines 11 to determine whether or not the touch sensor 10 is touch- And may be variously referred to as any other name such as a touch IC or the like.

The touch driver IC 30 includes a driving unit 31 for touch driving, a touch detection unit 32 for touch detection, a signal processing unit 33 for touch signal processing, a memory unit for storing touch data, A power supply unit 35 for power supply, a controller 36 for touch driving and detection control, a timing control unit 37 for timing control of touch detection, a voltage generating unit 38 for generating touch driving voltage, And a communication unit 39 for external communication, or the like.

The controller 36 may control one or more of the components and may interface with external components through the communication unit 39. [ For example, the controller 36 may be interlocked with a display drive IC (DDI) through the communication unit 36, or interlocked with a CPU of an electronic device such as a smart phone or the like.

The controller 36 may include at least one or more of the touch detection unit 32, the signal processing unit 33 and the timing control unit 37. The power supply unit 35 may include, for example, DC converter (DC / DC converter) that receives the DC power of the DC power supply and converts the DC power to DC power of various voltage levels (e.g., 6V, 9V, 12V, etc.).

The DC-DC converter DDC includes, for example, a boost converter for boosting an external direct-current power supply according to the pulse width of a switching pulse signal applied through the timing controller 37, and a buck- a buck-boost converter, and the like.

The present invention can provide a touch screen capable of efficiently removing noise caused by a switching pulse signal applied to a DC direct current converter (DDC) in the touch drive IC (TDI), for example.

A touch screen according to an embodiment of the present invention includes: a plurality of touch sensors arranged in a matrix of a plurality of rows and columns; A plurality of sensor signal lines connected to the touch sensors; And a touch driver IC for receiving touch signals generated by the touch sensors. The touch driver IC includes an analog front end circuit, a DC direct current converter, and a logic unit, The switching pulse signal applied to the DC-DC converter is synchronized with the drive pulse signal applied to the analog front-end circuit, so that the noise due to the switching pulse signal can be regularly detected.

The logic unit may synchronize the start point of the switching pulse signal with a start time point of the drive pulse signal or synchronize with a preset predetermined delay time.

Wherein the logic unit comprises: a position detector for detecting position information of a touch sensor in which a touch occurs based on an output signal of the analog front end circuit; A timing controller for synchronizing a switching pulse signal applied to the DC-DC converter based on a driving pulse signal applied to the analog front-end circuit; And a processor for removing the noise due to the switching pulse signal by a digital logical operation value.

The processor may detect and store noise due to the switching pulse signal during a non-touch period, and may remove noise due to the switching pulse signal by the digital logic operation value during a touch period.

The analog front-end circuit may include at least a sample hold and an analog-to-digital converter, and a subtracter for removing noise due to the switching pulse signal may be included between the sample hold and the analog-digital converter.

Wherein the logic unit comprises: a position detector for detecting position information of a touch sensor in which a touch occurs based on an output signal of the analog front end circuit; A timing controller for synchronizing a switching pulse signal applied to the DC-DC converter based on a driving pulse signal applied to the analog front-end circuit; And a processor for changing a reference value of the subtractor to remove noise caused by the switching pulse signal.

The processor detects and stores noise due to the switching pulse signal during a non-touch period, and removes noise caused by the switching pulse signal by changing a reference value of the subtracter during a touch period.

According to an embodiment of the present invention, a switching pulse signal applied to a DC-DC converter in a touch drive IC is synchronized with a drive pulse signal applied to an analog front-end circuit, and noise caused by the switching pulse signal is detected can do.

The noise generated by the switching pulse signal may be removed by a digital logic operation value or a reference value of a subtractor further configured between a sample hold (S / H) and an analog-to-digital converter (ADC) in the analog front- The noise due to the switching pulse signal can be removed.

1 is a diagram illustrating a configuration of a general touch screen.
FIG. 2 is a diagram illustrating a main configuration of a touch drive IC according to an embodiment of the present invention.
3 is a diagram illustrating a configuration of a logic unit according to an embodiment of the present invention.
4 is a diagram illustrating synchronization between a driving pulse signal of an analog front-end circuit and a switching pulse signal of a DC-DC converter according to an embodiment of the present invention.
FIG. 5 is a diagram that intuitively illustrates regular noise detected according to an embodiment of the present invention. FIG.
FIG. 6 is a diagram for intuitively illustrating a digital logic operation value according to an embodiment of the present invention.
7 is a diagram illustrating a further configuration of a subtractor according to another embodiment of the present invention.

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

The touch screen according to an embodiment of the present invention may be a capacitance type touch screen in which a plurality of touch sensors are arranged in a matrix of a plurality of rows and columns and may be touch detection using a finger or the like, Which may be a touch screen. The embodiment of the present invention is not limited thereto.

FIG. 2 is a diagram illustrating a main configuration of a touch drive IC according to an embodiment of the present invention.

The embodiment of the present invention can be applied to a capacitive touch screen 100 configured as described above with reference to Fig. 1, and the touch driver IC (TDI) is, for example, And may include an analog front end (AFE) circuit (not shown), a DC direct current converter (DDC) 55, and a logic unit 54, as shown in FIG.

The analog front end (AFE) circuit receives touch signals generated from touch sensors of respective columns (for example, first to fourth columns) and selectively outputs one of the touch signals A plurality of muxes 50 and a plurality of sample holders 51 for sampling and holding the output signals of the muxes 50, respectively.

The plurality of muxes 50 may be included in the touch drive IC (TDI) or may be installed in an external configuration on the front end of the touch drive IC. In the front end of the plurality of sample holders 51, And a plurality of amplifiers (not shown) for amplifying the respective touch signals may be installed.

The analog front end (AFE) circuit includes one mux 52 for receiving output signals of the sample hold 51 and selectively outputting one of the output signals, And an analog-to-digital converter (ADC) 53 for converting a signal from an analog signal into a digital signal.

The row selection control signal ROW_SEL output from the logic unit 54 may be applied to the plurality of muxes 50 and the logic unit 54 may be connected to the plurality of sample holders 51. [ A sample-and-hold control signal SHb to be output may be applied.

The column selection control signal COL_SEL output from the logic unit 54 may be applied to the one mux 52 and the output of the logic unit 54 may be supplied to the one analog digital converter 53. [ An analog-to-digital converted clock signal ADC_clk can be applied.

Here, the control signals and the clock signal may be referred to as any other names. For example, the control signals and the clock signal may be variously referred to as an analog front end clock (AFE_clock) signal or a drive pulse signal of an analog front end circuit, .

The DC-DC converted clock signal (DDC_clk) output from the logic unit 54 may be applied to the DC-DC converter 55, and the DC-DC converted clock signal may be, for example, a switching pulse signal, or the like.

According to the embodiment of the present invention, the logic unit 54 synchronizes the switching pulse signal applied to the DC-DC converter on the basis of the driving pulse signal applied to the analog front-end circuit, Can be detected regularly.

For example, the logic unit 54 may synchronize the starting point of the switching pulse signal with a start time point (AFE_start) of the driving pulse signal, or a predetermined delay time So that the switching noise generated by the switching pulse signal can be regularly detected.

3 is a diagram illustrating a configuration of a logic unit according to an embodiment of the present invention.

3, the logic portion 54 may include or partially include all of, for example, a position detector 541, a timing controller 542, a processor 543, and a storage 544, .

The position detector 541 can detect the touch position of the user's finger based on the digital touch signal input through the analog-to-digital converter (ADC) Here, the position detector 541 corresponds to a structure in a conventional touch-sensitive-liquid-crystal-integrated-circuit (IC), and thus a detailed description of the structure will be omitted.

The timing controller 542 controls the output timing of the driving pulse signal applied to the analog front end (AFE) circuit and the output timing of the switching pulse signal applied to the DC / DC converter 55 in cooperation with the processor 543 The output timing can be adjusted to synchronize.

For example, the timing controller 542 includes a row select control signal ROW_SEL, a sample hold control signal SHb, a column select control signal COL_SEL, and an analog to digital conversion The driving pulse signal of the analog front end circuit such as the clock signal ADC_clk and the output timing of the switching pulse signal of the DC / DC converter 55 can be adjusted and synchronized.

The processor 543 may be, for example, a microcontroller unit (MCU) or the like, or may be included in the controller 36 shown in FIG. 1 or may have a separate structure. The position detector 541 And the timing controller 542. The timing controller 542 may be a timing controller.

The processor 543 may provide the position information detected by the position detector 541, for example, a touch position coordinate value, to an external host (e.g., a CPU of a smart phone) (For example, switching noise) by using the digital logic operation value.

For example, the processor 543 detects a digital touch signal of a switching noise component generated by the switching pulse signal in at least one frame period during a non-touch period, And may be stored in the storage 544.

The processor 543 calculates a subtraction logical value for eliminating the touch detection error value due to the noise component by logical operation based on the noise component of the stored frame unit, The noise component due to the switching pulse signal can be removed using the subtraction logic value. A detailed description thereof will be given later.

4 is a diagram illustrating synchronization between a driving pulse signal of an analog front-end circuit and a switching pulse signal of a DC-DC converter according to an embodiment of the present invention.

In accordance with an embodiment of the present invention, the timing controller 542 included in the logic portion 54 operates in synchronization with the output timing of the drive pulse signal applied to the analog front end (AFE) And the output timing of the switching pulse signal applied to the DC / DC converter 55 may be adjusted and synchronized.

4, when the driving pulse signal of the analog front-end (AFE) circuit and the switching pulse signal of the DC-DC converter are not synchronized with each other, the starting point of the driving pulse signal (for example, (T1, t2) between the transition point of the switching pulse signal and the transition point of the switching pulse signal become irregular, switching noise can be irregularly detected.

On the other hand, when the drive pulse signal of the analog front end (AFE) circuit and the switching pulse signal of the DC direct current converter are synchronized with each other, the start point of the drive pulse signal (e.g., AFE_start) Since the time interval t0 between the transition points becomes zero or regular, switching noise can be regularly detected.

For example, the starting point of the switching pulse signal (DDC_Clock) of the DC / DC converter is made to coincide with the starting point (AFE_start) of the driving pulse signal of the analog front end (AFE) Since the time at which the sample hold 51 samples and holds the output signal of the mux 50 is synchronized with the switching pulse signal of the DC to DC converter 55 when synchronized with the delay time, Switching noise can be detected.

FIG. 5 is a diagram that intuitively illustrates regular noise detected according to an embodiment of the present invention. FIG.

For convenience of description of the embodiment of the present invention, it is assumed that 100 touch sensors (TS1 to TS100) are arranged in 10 rows (R1 to R10) and 10 columns (C1 to C10) .

5, when the switching pulse signal of the analog front end (AFE) circuit and the switching pulse signal of the DC / DC converter are not synchronized with each other, for example, when the switching noise is irregularly detected, An irregular noise (Random Noise) component is included in the touch detection value of one frame detected during the interval.

On the other hand, when the driving pulse signal of the analog front end (AFE) circuit and the switching pulse signal of the DC / DC converter are synchronized with each other and switching noise is regularly detected, the touch detection of one frame The value includes a Regular Noise component.

Here, FIG. 5 is an illustrative drawing that is intuitively simplified for convenience of description, and the embodiment of the present invention is not limited thereto.

FIG. 6 is a diagram for intuitively illustrating a digital logic operation value according to an embodiment of the present invention.

For convenience of description of the embodiments of the present invention, a further description will be given based on the example of FIG.

Referring to FIG. 6, the processor 543 converts a digital touch signal including a switching noise component, which is regularly detected during a non-touch period, into at least one frame, And store it in the storage 544. The storage 544 can be used as a storage unit.

The processor 543 may calculate a subtraction logical value based on the noise component of the stored frame unit. The subtraction logic value is used for efficiently removing the touch detection error value due to the noise component through logic operation and may be intermittently detected, calculated and updated during a non-touch period.

As shown in FIG. 6, for example, the subtraction logical value may be a value obtained by subtracting a detection value of a touch sensor including a regular noise component, as each individual value corresponding to each touch sensor included in one frame, Can be set to a value obtained by subtracting the total average value.

For example, when the detection values of the second row R2 and the third column C3 including the regular noise component are 51 and the total average value is 10, the values of the second row and the third column The subtraction logic value can be set to -41.

7 is a diagram illustrating a further configuration of a subtractor according to another embodiment of the present invention.

According to another embodiment of the present invention, the analog front end (AFE) circuit comprises at least a sample hold (SH) and an analog-to-digital converter (ADC), and between the sample hold and the analog- And a subtractor for eliminating noise due to the signal.

7, a plurality of subtractors 56 may be provided between the plurality of sample holders 51 and the one mux 52, and the processor 543 in the logic unit may be connected As described above, the noise due to the switching pulse signal is detected and stored during the non-touch period, and the noise due to the switching pulse signal is changed during the touch interval by changing the reference values Ref1 to Ref4 of the subtractors 56 Can be removed.

For example, the processor 543 arbitrarily changes and assigns a register value (e.g., 10 bits) corresponding to a subtraction value for each touch sensor in a DAC (Digital Analog Conversion) register 5431, (DAC) 57 input as the reference value Ref of the reference value (Ref) of the reference signal (Ref).

Accordingly, the reference value Ref of the subtractors 56 can be changed for each touch sensor in conjunction with the subtraction logic value, so that the switching noise component included in the output signal of the sample hold 51 can be changed It can be efficiently removed by using a subtractor.

Here, description contents of a register value to be allocated in the DAC register 5431 and changing a reference value of a component such as a subtractor or the like are equivalent to known technologies, and a detailed description of the technology will be omitted.

It is to be understood that the present invention is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and variations are possible within the scope of the technical idea of the present invention. It will be clear to those who have knowledge.

50: Mux 51: Sample Hold
52: Mux 53: Analog to Digital Converter
54: Logic part 55: DC direct current converter
56: subtracter 57: digital-to-analog converter
541: Position detector 542: Timing controller
543: Processor 544: Storage

Claims (7)

A plurality of touch sensors arranged in a matrix of a plurality of rows and columns;
A plurality of sensor signal lines connected to the touch sensors; And
And a touch driver IC for receiving touch signals generated by the touch sensors,
The touch drive IC includes an analog front end circuit, a DC direct current converter, and a logic unit,
The logic unit includes:
Wherein the controller is configured to synchronize a switching pulse signal applied to the DC-DC converter based on a driving pulse signal applied to the analog front-end circuit to regularly detect noise due to the switching pulse signal.
The method according to claim 1,
Wherein the logic unit synchronizes the start time point of the switching pulse signal with a start time point of the drive pulse signal or synchronizes with a preset predetermined delay time.
The method according to claim 1,
The logic unit includes:
A position detector for detecting position information of a touch sensor in which a touch occurs based on an output signal of the analog front end circuit;
A timing controller for synchronizing a switching pulse signal applied to the DC-DC converter based on a driving pulse signal applied to the analog front-end circuit; And
And a processor for removing the noise due to the switching pulse signal by a digital logical operation value.
The method of claim 3,
The processor comprising:
Wherein a noise due to the switching pulse signal is detected and stored during a non-touch period, and a noise due to the switching pulse signal is removed by the digital logic operation value during a touch period.
The method according to claim 1,
Wherein the analog front end circuit comprises:
At least a sample hold and an analog-to-digital converter,
And a subtracter for eliminating noise due to the switching pulse signal is provided between the sample hold and the analog digital converter.
6. The method of claim 5,
The logic unit includes:
A position detector for detecting position information of a touch sensor in which a touch occurs based on an output signal of the analog front end circuit;
A timing controller for synchronizing a switching pulse signal applied to the DC-DC converter based on a driving pulse signal applied to the analog front-end circuit; And
And a processor for changing a reference value of the subtractor to remove noise caused by the switching pulse signal.
The method according to claim 6,
The processor comprising:
Wherein the touch screen detects and stores noise due to the switching pulse signal during a non-touch period, and removes noise caused by the switching pulse signal by changing a reference value of the subtracter during a touch interval.

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