KR101461929B1 - Touch detecting apparatus and method using sinusoidal voltage - Google Patents

Abstract

According to an embodiment of the present invention, a touch detecting apparatus includes: a plurality of sensor pads which form touch capacitance regarding a touch input means; a driving unit which applies a sinusoidal voltage to each sensor pad; an amplifying unit which has a first input terminal connected to output of the sensor pad, and a second input terminal connecting a preset reference voltage; a first switch which connects the output of the sensor pad with the first input terminal of the amplifying unit; a second switch which controls an electric potential between the first input terminal and an output terminal of the amplifying unit; and a touch detection unit which detects a touch based on variation of a voltage at the output terminal of the amplifying unit according to the touch capacitance. The first switch and the second switch are turned on or off alternately.

Description

TECHNICAL FIELD [0001] The present invention relates to a touch detection apparatus and a touch detection method using a sine wave voltage,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for detecting a touch using a sinusoidal voltage, and more particularly, to a touch detection apparatus and method for detecting a touch by applying a sinusoidal voltage to a sensor pad.

The touch screen panel is a device for inputting a command of a user by touching a character or a figure displayed on the screen of the image display device with a finger or other contact means of a person, and is attached and used on the image display device. The touch screen panel converts a contact position that is touched by a human finger or the like into an electrical signal, and the converted electrical signal is used as an input signal.

As a method of implementing a touch screen panel, a resistive film type, a light sensing type, and a capacitive type are known. Among them, the capacitive touch panel converts the contact position into an electrical signal by sensing a change in the capacitance that the conductive sensing pattern forms with other peripheral sensing patterns or the ground electrode when a human hand or an object touches.

1 is an exploded top view of an example of a conventional capacitive touch screen panel.

1, a touch screen panel 10 includes a transparent substrate 12 and a first sensor pattern layer 13, a first insulating layer 14, and a second sensor pattern layer (not shown) sequentially formed on a transparent substrate 12 15, a second insulating film layer 16, and a metal wiring 17.

The first sensor pattern layer 13 may be connected on the transparent substrate 12 along the lateral direction and connected to the metal wiring 17 on a row-by-row basis.

The second sensor pattern layer 15 may be connected to the first insulating layer 14 along the column direction and alternately arranged with the first sensor pattern layer 13 so as not to overlap the first sensor pattern layer 13 . In addition, the second sensor pattern layer 15 is connected to the metal wiring 17 on a row basis.

When a human finger or a contact means is brought into contact with the touch screen panel 10, a change in capacitance according to the contact position is transmitted to the drive circuit side through the first and second sensor pattern layers 13 and 15 and the metal wiring 17 do. Then, the contact position is determined as the change in capacitance transferred is converted into an electrical signal.

However, the touch screen panel 10 must have a separate pattern of a transparent conductive material such as indium tin oxide (ITO) on each of the sensor pattern layers 13 and 15. The sensor pattern layers 13, 15, the thickness of the insulating layer 14 is increased.

In addition, since the touch detection can be performed by accumulating the changes of capacitance slightly generated by the touch several times, it is necessary to detect the capacitance change at a high frequency. In order to sufficiently accumulate the capacitance change within a predetermined time, a metal wiring is required to maintain a low resistance, which thickens the bezel at the edge of the touch screen and generates an additional mask process.

To solve this problem, a touch detection apparatus as shown in Fig. 2 has been proposed.

2 includes a touch panel 20, a driving device 30, and a circuit board 40 connecting the two.

The touch panel 20 includes a plurality of sensor pads 22 formed on a substrate 21 and arranged in the form of a polygonal matrix and a plurality of signal wirings 23 connected to the sensor pads 22.

Each signal wiring 23 has one end connected to the sensor pad 22 and the other end extending to the lower edge of the substrate 21. The sensor pad 22 and the signal wiring 23 can be patterned on the cover glass 50. [

The driving device 30 sequentially selects a plurality of sensor pads 22 one by one to measure the electrostatic capacitance of the corresponding sensor pad 22, thereby detecting whether or not a touch is generated.

In order for the response speed of the touch sensing device shown in FIG. 2 to be quick and accurate, it is necessary to control the noise generated during the touch and the parasitic capacitance generated between each sensor pad 22. The noise generated in the electrostatic capacitive touch-sensing device occurs when noise due to an external environment (e.g., LCD power supply noise), a sensor pad, a circuit board, a touch IC, etc. affect the adjacent sensor pad 22 do. In addition, the parasitic capacitance is caused by the capacitive coupling between the sensor pads 22, the manufacturing process, and the like, which adversely affects touch detection.

Such noise and parasitic capacitance may cause errors in touch recognition, resulting in a reduction in signal-to-noise (SNR) that determines the touch detection performance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional art, and it is an object of the present invention to provide a touch detection apparatus and method for detecting touch based on a voltage variation according to a touch capacitance using a sine wave voltage.

According to an aspect of the present invention, there is provided a touch sensing device including: a plurality of sensor pads for forming a touch capacitance in relation to touch input means; A driver for applying a sinusoidal voltage to each sensor pad; An amplifier having a first input connected to an output of the sensor pad and a second input connected to a preset reference voltage; A first switch for connecting an output of the sensor pad and a first input terminal of the amplification unit; a second switch for controlling a potential between a first input terminal and an output terminal of the amplification unit; And a touch detection unit for detecting whether or not a touch is made based on a voltage variation at an output terminal of the amplification unit according to the touch capacitance, wherein the first switch and the second switch are alternately turned on or off, Lt; / RTI >

The first switch may be turned off when the instantaneous value of the sine wave voltage applied to each sensor pad reaches a maximum value.

The touch detection unit may detect the touch by measuring a maximum value of the voltage variation at a moment when the instantaneous value of the sine wave voltage applied to the sensor pad becomes a maximum value.

And a blocking unit for removing a frequency component that is not included in a predetermined threshold range based on the frequency of the sine wave voltage among the voltage levels at the output terminal of the amplifying unit.

The driving unit may apply the sinusoidal voltage to a conductive object disposed adjacent to the sensor pad.

The second switch may be turned on for a predetermined time at a time point when the instantaneous value of the sine wave voltage applied to each of the sensor pads becomes a minimum value, thereby setting a reference value for detecting whether or not the touch is detected.

According to another embodiment of the present invention, there is provided a method of driving a plasma display panel, comprising: applying a sinusoidal voltage to a sensor pad connected to a first input terminal of an amplifier; Blocking the connection between the output of the sensor pad and the first input of the amplifier when the instantaneous value of the sinusoidal voltage has a maximum value; And detecting whether or not the touch is detected on the basis of an output terminal voltage of the amplifier relative to a reference voltage applied to a second input terminal of the amplifier.

The step of applying the sinusoidal voltage may include applying the sinusoidal voltage to a conductive object disposed adjacent to the sensor pad.

Wherein the control unit disconnects the connection between the sensor pad and the first input terminal before the sine wave voltage application step and connects the first input terminal and the output terminal of the amplification unit to each other for a predetermined time, The step of initializing the amount of charge of the capacitance may be further included.

According to the touch detection apparatus and method of the present invention, not only a sinusoidal voltage is applied to a sensor pad, but also other frequency components excluding a frequency component of a sinusoidal voltage applied to a sensor pad are blocked, And the influence on the parasitic capacitance can be minimized.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the description of the present invention or the composition of the invention described in the claims.

1 is an exploded plan view of an example of an electrostatic touch screen panel.
2 is an exploded top view of a conventional touch detection device.
3 is a diagram illustrating a structure of a touch detection apparatus according to an embodiment of the present invention.
4 is a circuit diagram illustrating a touch detection unit according to an embodiment of the present invention.
5 is an exemplary waveform diagram of a touch detection unit according to an embodiment of the present invention.
6 is a waveform diagram illustrating a change in the output terminal voltage of the amplifying part according to a sinusoidal voltage when a touch is generated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

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

3 is a diagram illustrating a structure of a touch detection apparatus according to an embodiment of the present invention.

Referring to FIG. 3, the touch detection apparatus includes a touch screen panel 100 and a driving apparatus 200.

The touch screen panel 100 includes a plurality of signal pads 110 connected to a plurality of sensor pads 110 and a plurality of signal pads 120 connected to the sensor pads 110.

Each sensor pad 110 forms a touch capacitance Ct with a touch input tool, such as a finger or a conductor, as a patterned electrode on a substrate to detect a touch input. In addition, each sensor pad 110 outputs a sensing signal according to the touch state of the touch input tool in response to the sine wave voltage Vg1. Here, the sensing signal may be a voltage change amount of the output voltage of the touch detection unit 210 due to the touch capacitance Ct or predetermined data used for touch detection, touch coordinate calculation, .

For example, the plurality of sensor pads 110 may be rectangular or rhombic, but may be other shapes, or may be polygonal shapes of uniform shape. The plurality of sensor pads 110 may be arranged in the form of a matrix of adjacent polygons.

Each sensor pad 110 may be formed of a transparent conductor. For example, each sensor pad 110 may be formed of a transparent material such as ITO (Indium Tin Oxide), ATO (Antimony Tin Oxide), CNT (Carbon Nano Tube), IZO (Indium Zinc Oxide) However, in another example, each sensor pad 110 may be formed of a metallic material.

The driving device 200 may include a touch detection unit 210, a touch information processing unit 220, a memory 230, and a control unit 240, and may be implemented as one or more integrated circuit (IC) chips.

The touch detection unit 210, the touch information processing unit 220, the memory 230, and the control unit 240 may be separated, or two or more components may be integrated.

The touch detection unit 210 may include a plurality of switches connected to each of the plurality of sensor pads 110 and the plurality of signal lines 120 and a plurality of capacitances. The touch detection unit 210 receives the drive control signal from the control unit 240 and drives circuits for touch detection (e.g., a plurality of switches, a plurality of capacitances, etc.) And outputs a voltage. The touch detection unit 210 may further include an amplifier and an analog-to-digital converter. The touch sensing unit 210 may convert, amplify, or digitize the voltage variation of each sensor pad 110 and store the same in the memory 230.

The touch information processing unit 220 processes the digital voltage stored in the memory 230 to generate necessary information such as touch state, touch area, and touch coordinates. For example, the touch information processing unit 220 may output a result of comparing the output value output from the touch detection unit 210 with the digital voltage stored in the memory 230 in response to the drive control signal of the control unit 240 .

The memory 230 stores the digital voltage based on the difference in the voltage change detected from the touch detection unit 210, predetermined data used for touch detection, area calculation, touch coordinate calculation, or data received in real time.

The control unit 240 controls the touch detection unit 210 and the touch information processing unit 220. The control unit 240 may include a micro control unit (MCU), and may perform predetermined signal processing through a firmware.

The operation of the touch screen panel and the touch detection unit shown in FIG. 3 will be described in detail with reference to FIGS. 4 and 5. FIG.

FIG. 4 is a circuit diagram illustrating a touch detection unit according to an embodiment of the present invention, and FIG. 5 is an exemplary waveform diagram of a touch detection unit according to an embodiment of the present invention.

4, the touch detection unit 210 is connected to each sensor pad 110 through each signal line 120 and includes a first switch 211 and a second switch 212 for performing a switching operation, A capacitance C_FB, an amplification section 213, and a blocking section 214.

The first switch 211 and the second switch 212 for switching operation, the feedback capacitance C_FB, the amplification unit 213 and the blocking unit 214 are connected to the sensor pads 110 and the signal lines 120, Groups can be formed one by one.

The first switch 211 is connected between each sensor pad 110 and the first input terminal P of the amplifier 213. The first switch 211 may be a field effect transistor, for example, a gate may be supplied with a drive control signal FDRV_S and a source may be supplied with a sinusoidal signal Vg1 The drain may be connected to the first input of the amplifier 213. Of course, the source of the first switch 211 may be connected to the first input terminal of the amplifier 213, and the sine wave signal Vg1 may be applied to the drain. Here, the drive control signal FDRV_S and the sinusoidal signal Vg1 may be controlled by the control unit 240. [

The second switch 212 can control the potential between the first input terminal P and the output terminal Q of the amplifier 213. The second switch 212 may comprise at least two field effect transistors 212-1 and 212-2 as shown in Figure 4 and two field effect transistors 212-1 and 212-2 And may be connected to each other in series. In this case, the first transistor 212-1 may be connected between the first input terminal P of the amplifier 213 and the second transistor 212-2, and the second transistor 212-2 may be coupled between the first And may be connected between the transistor 212-1 and the output terminal Q of the amplification unit 213. [ Both the first transistor 212-1 and the second transistor 212-2 are controlled in synchronization with the control signal FB_S. Meanwhile, a reference voltage Vref may be applied between the first transistor 212-1 and the second transistor 212-2.

The control signal FB_S and the reference signal Vref may be controlled by the control unit 240 such that the first transistor 212-1 and the second transistor 212-1 are turned on The voltage of the first input terminal P and the output terminal Q of the amplifying unit 213 are applied to the reference voltage Vref.

In FIG. 4, the second switch 212 includes two transistors, but the present invention is not limited to this, and the second switch 212 may be formed of a single transistor.

For example, the second switch 212 may be connected in parallel with the feedback capacitance C_FB and may be controlled by the control signal FB_S. In this case, when the second switch 212 is turned on, the reference voltage Vref connected to the second input terminal of the amplifier 213 is fed back to the first input terminal P and the output terminal Q of the amplifier 213, The voltage may be the reference voltage Vref.

That is, it can be seen that the operation of the second switch 212 is the same in the case of the two transistors 212-1 and 212-2 and in the case of the single transistor. Hereinafter, the case where the second switch 212 is composed of two transistors 212-1 and 212-2 will be described.

Meanwhile, although the first switch 211 and the second switch 212 are illustrated as transistors, other elements capable of performing a switching operation can be used instead of the transistor. For example, a relay, a MOS (Metal Oxide Semiconductor) switch, a BJT (Bipolar Junction Transistor), a MOSTET (Metal Oxide Semiconductor Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), a TFT (Thin Film Transistor) (Operational Amplifier), and they may be formed by the homologous or interspecific combination of the two. The relay may be a 4-terminal type device in addition to the 3-terminal type device.

Hereinafter, for convenience of explanation, the first switch 211 and the second switch 212 are turned on or off according to the supplied control signals FDRV_S and FB_S, .

The reference voltage Vref is a voltage that is set in advance to compare the voltage variation? V at the output terminal Q of the amplifier 213 depending on whether or not the touch is generated. It can be adjusted to the reference voltage Vref, whereby the touch can be detected according to the voltage difference with the reference voltage Vref.

In FIG. 4, the touch capacitance Ct represents a capacitance formed between the sensor pad 110 and a touch input tool such as a finger of a user when the user touches the sensor pad 110.

The amplifying unit 213 has a second input terminal for connecting the first input terminal P connected to the output of the sensor pad 110 to the reference voltage Vref. The feedback capacitance C_FB may be included between the first input terminal P and the output terminal Q of the amplifier 213. The output terminal Q of the amplification unit 213 may be connected to the blocking unit 214.

The blocking unit 214 can remove a frequency component that is not included in a preset threshold range based on the frequency of the sinusoidal voltage Vg1 in the voltage level at the output terminal of the amplifier 213. [ The blocking unit 214 removes the parasitic capacitance and the noise signal that may occur in the vicinity of the touch detection. For example, the blocking unit 214 may set a certain range including the frequency of the sinusoidal signal Vg1 to a threshold range, and remove other frequencies except for the set frequency, thereby reducing the influence of noise and parasitic capacitance Eg, touch recognition errors, etc.) can be minimized. At this time, the blocking unit 214 may include any one of a low-pass filter, a high-pass filter, and a band-pass filter.

Here, the noise may include noise due to the external environment (such as LCD power supply noise), noise due to the sensor pad, circuit board, touch IC, etc., and parasitic capacitance may occur in the sensor pad 110, And may include any parasitic capacitance generated by the touch detection unit 210, the touch screen panel, and the image display device.

The driving unit 215 applies the sine wave voltage Vg1 to the sensor pad 110. [ At this time, the driving unit 215 may apply a sinusoidal voltage Vg1 to a conductive object disposed adjacent to the sensor pad 110 instead of the sensor pad 110, so that a signal may be induced to the sensor pad 110. [ The sinusoidal voltage Vg1 may be a signal that maintains a predetermined period and a single frequency, such as an AC sine signal.

Hereinafter, the operation of the circuit shown in Fig. 4 will be described with reference to Fig. At this time, the sine wave voltage Vg1 is a sine wave signal having a minimum value of 0V and a maximum value of 1.8V, and the reference voltage Vref is assumed to be 0.9V. Here, when the control signal FB_S is a low voltage (0V), the second switch 212 is turned off. When the control signal FB_S is a high voltage (1.8V), the second switch 212 is turned on and the control signal FDRV_S becomes a low voltage , The first switch 211 is turned off and the first switch 211 is turned on when the voltage is high (1.8 V).

In the meantime, for convenience of explanation, the case where a touch occurs in the sensor pad 110 (Full Touch and 1/2 Touch) will be described first before a description of the case where no touch occurs (No Touch) .

5, the minimum value of the voltage value V (Q) of the output terminal Q of the amplifier 213 when the entire area of the sensor pad 110 is touched is 0.2 V and the area of the sensor pad 110 It is assumed that the voltage value V (Q) of the output terminal Q of the amplifying unit 213 when half is touched is 0.6V. The voltage value V (Q) of the output terminal Q of the amplifier 213 is different according to the touch area where the touch input tool is touched to the sensor pad 110. Therefore, The voltage value V (Q) of the output terminal Q of the amplifier 213 can be measured or set in advance for each area.

First, a case where the touch input tool touches the entire area of the sensor pad 110 (full touch) will be described with reference to FIG. When a touch is generated, a touch capacitance Ct is formed between the sensor pad 110 and the touch input tool.

)은 초기화된다. 또한, 증폭부(213)의 출력단(Q)의 전압(V(Q))은 기준 전압(Vref)인 상태로서, 터치 여부를 검출하기 위한 기준 값이 된다. T1 구간에서의 피드백 정전용량(C_FB) 전하량(

)을 수학식으로 나타내면 다음과 같다.In the T1 interval, when the second switch 212 is turned on while the first switch 211 is off, the reference voltage Vref is connected through the second switch 212, The voltage V (Q) of the first input terminal P and the output terminal Q of the reference voltage generator 213 is 0.9 V which is the reference voltage Vref. At this time, both ends of the feedback capacitance are applied with the reference voltage (Vref) and there is no potential difference. Therefore, the amount of charge (C_FB) of the feedback capacitance

Is initialized. The voltage V (Q) of the output terminal Q of the amplifier 213 is a reference voltage Vref and is a reference value for detecting whether or not a touch is made. The feedback capacitance (C_FB) charge amount in the T1 section (

) Can be expressed by the following equation.

[Equation 1]

의 전하량은 터치 정전 용량과 피드백 정전용량에서 공유되어 증폭부(213)의 출력단(Q)의 전압(Vout)이 점차 감소하게 된다. 즉, 센서 패드(110)에 인가되는 정현파 전압(Vg1) 및 터치 정전용량(Ct)의 전하량 변화에 의해 증폭부(213)의 피드백 정전용량에서의 전하량은 다음 [수학식 2]와 같이 되고, 피드백 정전용량에서의 전압 변동분(△V)으로 정리하면 [수학식 3]과 같이 된다.The sensor pad 110 is connected to the first input terminal P of the amplifier 213 when the first switch 211 is turned on after the second switch 212 is turned off,

The voltage Vout of the output terminal Q of the amplifier 213 is gradually reduced. That is, the amount of charge in the feedback capacitance of the amplifier 213 due to the change in the amount of charge of the sinusoidal voltage Vg1 and the touch capacitance Ct applied to the sensor pad 110 is expressed by the following equation (2) (3) is summarized by the voltage variation (? V) in the feedback capacitance.

&Quot; (2) "

&Quot; (3) "

Here, Vref is the reference voltage, Ct is the touch capacitance, C_FB is the feedback capacitance, Vg1 is the instantaneous value of the sine wave voltage, and DELTA V is the voltage variation in the feedback capacitance C_FB.

According to Equation (3), DELTA V maintains the reference voltage Vref in the T1 interval, and gradually changes in accordance with the magnitude of the touch capacitance Ct and the instantaneous value Vg1 of the sinusoidal voltage in the T2 interval. Particularly, the voltage V (Q) of the output terminal Q of the amplifier 213 becomes the minimum value of 0.2 V at the instant when the instantaneous value Vg1 of the sinusoidal voltage becomes the maximum value (1.8 V).

In the T3 period, the first switch 211 is turned off. When the first switch 211 is turned off, the sensor pad 110 to which the sine wave voltage Vg1 is applied is not connected to the first input terminal P of the amplification unit 213. The first switch 211 is turned off and the sine wave voltage Vg1 is applied to the first input terminal P of the amplification unit 213 at the time when the sine wave voltage Vg1 reaches the maximum value (1.8 V) The voltage difference between the reference voltage Vref and the reference voltage Vref is maintained at 0.7 V (0.9 V - 0.2 V) in the state where the maximum value of ΔV is not satisfied.

That is, when the instantaneous value of the sinusoidal voltage Vg1 applied to the sensor pad 110 reaches a maximum value, the touch detection unit 210 detects the voltage difference of the output terminal Q of the amplification unit 213, The maximum value of the voltage variation? V of the output terminal Q of the switch 213 can be measured.

5, the voltage V (Q) of the output Q of the amplifying unit 213 is 0.2V, which is the minimum value, and the maximum value of the voltage variation becomes 0.7V. That is, the voltage V (Q) of the output terminal Q of the amplifier 213 is measured as the lowest value, so that not only a touch occurs in the sensor pad 110 but also the total area of the sensor pad 110 Touch).

Thereafter, when the second switch 212 is turned on, the voltage of the output terminal Q of the amplifier 213 may become the reference voltage Vref in the initial state.

Meanwhile, a case where the touch input tool touches a half area (1/2 touch) of the sensor pad 110 will be described.

When the first switch 211 is turned off and the second switch 212 is turned on in the period T4, the voltages of the first input terminal P and the output terminal Q of the amplifier 213 are set to 0.9 V.

The first switch 211 is turned on after the second switch 212 is turned off so that the voltage V (Q) of the output terminal Q of the amplifying unit 213 is changed according to the following equation . Here, the voltage V (Q) of the output terminal Q of the amplifier 213 is 0.6 V at the instant when the instantaneous value Vg1 of the sinusoidal voltage becomes the maximum value (1.8 V).

The first switch 211 is turned off and the sensor pad 110 to which the sine wave voltage Vg1 is applied is not connected to the first input terminal P of the amplification unit 213. [ That is, at the time when the sine wave voltage Vg1 reaches the maximum value (1.8 V), the first switch 211 is turned off and the sine wave voltage Vg1 is applied to the first input terminal P of the amplification unit 213 The voltage variation of the output terminal Q of the amplifier 213 is maintained at 0.3 V (0.9 V - 0.6 V).

The voltage V (Q) of the output terminal Q of the amplifier 213 is 0.6 V and the maximum value of the voltage variation becomes 0.3 V, as shown in FIG. That is, since the voltage V (Q) of the output terminal Q of the amplifier 213 is measured as the lowest value, it can be seen that half of the area of the sensor pad 110 is touched.

That is, when half of the area of the sensor pad 110 is touched, the voltage variation of the output terminal Q of the amplification part 213 is 0.3 V, and 0.7 V when the entire area of the sensor pad 110 is touched The voltage difference is smaller.

This is because the voltage of the output terminal Q of the amplifier 213 varies according to the value of the touch capacitance Ct according to Equation (3). As the area of the touch pad 110 touching the touch pad 110 increases, the value of DELTA V decreases as the value of the touch capacitance Ct increases, and the value of V (Q) becomes larger . That is, the voltage variation (? V) of the output terminal (Q) of the amplifier 213 differs according to the area of the sensor pad 110 where the touch input tool is touched.

Accordingly, when the voltage detection unit 210 measures the voltage variation? V of the output terminal Q of the amplification unit 213 according to the touch capacitance Ct, the touch detection unit 210 can calculate the touch area have.

Next, a case where the touch input tool is not touched to the sensor pad 110 (No touch) will be described.

When the first switch 211 is turned off and the second switch 212 is turned on, the voltage of the first input terminal P and the output terminal Q of the amplifier 213 becomes 0.9 V which is the reference voltage Vref.

When the first switch 211 is turned on after the second switch 212 is turned off, the voltage V (Q) of the output terminal Q of the amplifier 213 is calculated according to the following equation (3). The sensor pad 110 is connected to the first input terminal P of the amplifying unit 213 so that the sine wave voltage Vg1 is applied but the touch capacitance Ct is 0, The voltage V (Q) of the transistor Q is maintained at 0.9V.

Thereafter, when the sine wave voltage Vg1 reaches the maximum value (1.8 V), that is, when the first switch 211 is turned off and the sine wave voltage Vg1 is applied to the first input terminal P of the amplification unit 213 The voltage V (Q) of the output terminal Q of the amplifier 213 remains the reference voltage Vref even when the pad 110 is not connected, and there is no voltage difference.

5, the first switch 211 and the second switch 212 are turned on or off regardless of whether the touch input tool is touched to the sensor pad 110 (No Touch) The output terminal Q of the unit 213 maintains the reference voltage Vref constantly.

Accordingly, the touch detection unit 210 can detect whether or not the touch is detected based on the voltage variation at the output terminal of the amplification unit 213 according to the touch capacitance. At this time, the touch detection unit 210 applies a sinusoidal voltage to the sensor pad 110, and controls the plurality of switches to output the voltage of the sensor pad 110 through a variation of the output voltage V (Q) of the amplification unit 213 based on the reference voltage and the sine- Touch detection and touch area can be calculated. As an example, the voltage at the output terminal (Q) of the amplifier unit 213 when it is not touched (No Touch) can be a reference value of the voltage variation that is the basis of touch detection.

6 is a waveform diagram illustrating a change in the output terminal voltage of the amplifying part according to a sinusoidal voltage when a touch is generated. 6 is a graph showing the relationship between the output voltage of the amplifying part and the output voltage of the amplifying part according to the variation of the sine wave voltage Vg1 when a touch occurs (Full Touch and 1/2 Touch) FIG. Here, the horizontal axis represents time (Time) and the vertical axis represents the output terminal voltage value (Vout) of the amplification section. The full touch is a waveform showing the change of the output terminal voltage of the amplifying part when the entire area of the sensor pad 110 is touched and the Half Touch is a waveform showing the change of the output terminal voltage of the amplifying part when the entire area of the sensor pad 110 is touched. ) Is touched to half of the area of the amplifying part.

For convenience of explanation, FIG. 6 shows a sinusoidal voltage Vg1 at the time of touch generation and an output terminal voltage of the amplification unit when a touch occurs in the waveform diagram shown in FIG. 5 in one drawing.

First, a case where the touch input tool is touched to the entire area (full touch) of the sensor pad 110 will be described.

When the second switch 212 is turned on in the state that the first switch 211 is off, the reference voltage is connected through the second switch, and the output terminal voltage Vout of the amplification unit is initially V (Q) .max .

Next, when the first switch 211 is turned on after the second switch 212 is turned off, the sensor pad 110 to which the sinusoidal voltage Vg1 is applied is connected so that the output terminal voltage Vout of the amplification part gradually decreases When the instantaneous value Vg1 of the sinusoidal voltage is the maximum value Vg1.max, the output terminal voltage Vout of the amplifier becomes the minimum value V (Q) .min.

Thereafter, when the instantaneous value Vg1 of the sine-wave voltage is the lowest value (Vg1.min) while the first switch 211 is turned off and the second switch 212 is turned on, The state V (Q) .max. 5, when the first switch 211 is turned off, the sensor pad to which the sinusoidal voltage Vg1 is applied is not connected and the voltage Vout of the output terminal becomes the minimum value V (Q) .min1 The output terminal voltage Vout of the amplifying part may become V (Q) .max value immediately after the second switch 212 is turned on after the second switch 212 is turned on.

Similarly, in the case where the touch input tool touches half the area (1/2 touch) of the sensor pad 110, when the whole area (full touch) of the sensor pad 110 is touched, When the instantaneous value Vg1 is the maximum value Vg1.max, the output terminal voltage Vout of the amplification section becomes the minimum value V (Q) .min2 and the instantaneous value Vg1 of the sine wave voltage becomes the minimum value Vg1.min, , The output terminal voltage Vout of the amplifying part becomes the initial value V (Q) .max again.

The minimum value V (Q) .min2 of the output terminal voltage Vout of the amplifying part has a larger value than the case where the entire area of the sensor pad 110 is touched (V (Q) .min1) . In other words, when the half area (1/2 touch) of the sensor pad 110 is touched, the voltage variation? V? Of the output terminal of the amplification part is smaller than the voltage variation? Is smaller by about 1/2 than the voltage variation? V?

Accordingly, it is understood that the output terminal voltage changes in accordance with the change of the sinusoidal voltage Vg1 when the touch is generated, but it is understood that the voltage variation? V varies depending on the touch area.

The present invention is not limited to this. However, the present invention is not limited to this, and the sine wave voltage Vg1 may be applied to the conductive object disposed adjacent to the sensor pad 110 It is possible. Accordingly, an electric field may be formed between the conductive object and the sensor pad 110, and a signal may be induced to the sensor pad 110 by the electric field. That is, the present invention is also applicable to a touch detection by a mutual method.

In the above description, the sine wave voltage Vg1 is 0 to 1.8 V and the reference voltage Vref is 0.9. However, it should be understood that the scope of the present invention is not limited to the above values.

The touch detection apparatus according to an embodiment of the present invention uses a sine wave signal (e.g., Sine type AC signal) instead of a rectangular wave type signal (e.g., a rectangular wave type signal) By eliminating frequencies other than the frequency, it is possible to minimize the influence of noise and parasitic capacitance generated when the touch screen panel is driven.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (9)

A plurality of sensor pads forming a touch capacitance in relation to the touch input means;
A driver for applying a sinusoidal voltage having a specific frequency to each sensor pad;
An amplifier having a first input connected to an output of a specific one of the plurality of sensor pads and a second input connected to a predetermined reference voltage;
A second switch for controlling the potential between the first input terminal and the output terminal of the amplification unit and being turned on or off alternately with the first switch, the first switch connecting the output of the specific sensor pad and the first input terminal of the amplification unit; And
A feedback capacitance connected between a first input terminal and an output terminal of the amplification unit and sharing a charge and a touch capacitance formed on the specific sensor pad when the first switch is in an ON state; And
And a touch detection unit for detecting whether or not a touch is made based on a voltage variation at an output terminal of the amplification unit according to the touch capacitance in a state that the first switch is turned off after the charge sharing,
Touch detection device.
The method according to claim 1,
Wherein the first switch is turned off when the instantaneous value of the sine wave voltage applied to each sensor pad reaches a maximum value.
3. The method of claim 2,
Wherein the touch detection unit detects the touch by measuring a maximum value of the voltage variation at a moment when an instantaneous value of the sine wave voltage applied to the sensor pad becomes a maximum value.
The method according to claim 1,
And a blocking section for removing a frequency component that is not included in a preset threshold range based on the frequency of the sine wave voltage among the voltage levels at the output terminal of the amplifying section.
The method according to claim 1,
Wherein the driving unit applies the sine wave voltage to a conductive object disposed adjacent to the sensor pad.
The method according to claim 1,
Wherein the second switch is turned on for a predetermined time at a time point when the instantaneous value of the sine wave voltage applied to each of the sensor pads becomes a minimum value to set a reference value for detecting whether or not the touch is detected.
Applying a sinusoidal voltage to a sensor pad connected to a first input of the amplifying unit;
Blocking the connection between the output of the sensor pad and the first input of the amplifier when the instantaneous value of the sinusoidal voltage has a maximum value; And
Detecting whether or not a touch is made based on an output terminal voltage of the amplifying part with respect to a reference voltage applied to a second input terminal of the amplifying part.
8. The method of claim 7,
Wherein the step of applying the sinusoidal voltage comprises:
And applying the sinusoidal voltage to a conductive object disposed adjacent the sensor pad.
8. The method of claim 7,
Before the step of applying the sinusoidal voltage,
The step of disconnecting the connection between the sensor pad and the first input terminal and connecting the first input terminal and the output terminal of the amplification unit to each other for a predetermined time to initialize the amount of charge of the feedback capacitance connected between the first input terminal and the output terminal ≪ / RTI >

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