KR101554247B1 - Capacitive type touch input device with structure reducing effect from stray capacitance - Google Patents

Abstract

In a touch detection apparatus according to the present invention, a touch input detection circuit detecting whether or not there is a touch input for an electrode controls a potential of the electrode for detecting the touch input. At this time, a potential which follows a pattern of the potential of the electrode is applied to another electrode capacitively coupled to the electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a capacitive touch input device having a structure for reducing the influence of a stray capacitance,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitive touch input device for user input, and more particularly, to a touch input device having a configuration for eliminating unwanted influences by other electrodes capacitively coupled to a sensing target electrode.

When an object such as a human finger is present near the conductor, a capacitance is formed between the conductor and the finger. Such a capacitance may provide a path of current flow between the conductor and the finger. The magnitude of the capacitance may vary depending on the distance between the conductor and the fingers.

The electrostatic touch input device uses a principle described above to arrange a plurality of conductors on a surface of a touch panel included in a touch input device and to connect the plurality of conductors to a specific conductor Detecting whether or not a touch input is made by detecting a phenomenon that a magnitude of a flowing current varies. Accordingly, the electrostatic touch input device may include a touch input detection circuit for measuring the magnitude of the current. The capacitive touch input device may function as a component of a user device such as, for example, a smart phone.

Depending on the arrangement relationship among the plurality of conductors, mutual capacitance may be formed between one conductor and another conductor. At this time, while detecting whether or not there is a touch input to the one conductor, the current flowing through the one conductor by the mutual capacitance may leak through the path provided by the mutual capacitance. Since the magnitude of the leakage current is difficult to predict accurately, it is difficult to accurately compensate for the influence of the leakage current on the touch input detection circuit. Accordingly, there is a need for a technique for disposing electrodes of a touch panel or minimizing the magnitude of the leakage current so that the mutual capacitance component does not occur.

The present invention provides a structure of a touch input device for minimizing the influence of mutual capacitance generated between electrodes disposed on a touch panel.

In the present invention, in order to solve the above-described problems, it is preferable that when the touch input detection circuit measures a current flow of a specific electrode disposed on a touch panel, a potential of another electrode arranged to be capacitively coupled with the specific electrode, This makes it equal to or similar to the potential. In this way, the voltage difference between the specific electrode and the other electrode is minimized, and leakage of the measurement current due to capacitive coupling is minimized, thereby increasing the reliability of the measurement result of the touch input detection circuit.

A touch input device provided according to an aspect of the present invention includes a touch input detection circuit (110); A first electrode (ER4) for detecting whether or not a touch input is detected by the touch input detection circuit and whose potential is controlled by the touch input detection circuit; At least one second electrode (EC1 to EC9) forming a mutual capacitance with the first electrode; And a stray capacitance compensation circuit (120) adapted to apply a compensation potential (VS) following the potential pattern (V _VIN ) of the first electrode to the second electrode.

Here, the first electrode extends along a first direction on a touch panel included in the touch input device, and the second electrode extends along a second direction different from the first direction on the touch panel, The first electrode and the second electrode are insulated from each other, and a crossing region may exist between the first electrode and the second electrode.

The touch input detection circuit includes a first operational amplifier (OA1) and a second operational amplifier (OA2), and the first electrode is connected to the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier A first reference voltage VREF_H is applied to a non-inverting input terminal of the first operational amplifier, and a predetermined second reference voltage VREF_H is applied to a non-inverting input terminal of the second operational amplifier, (VREF_L) may be applied.

At this time, the potential of the first electrode has a pattern of a pulse train for switching between the first reference voltage and the second reference voltage, and the compensation potential may have the same time variation pattern as the pulse train.

At this time, the compensation potential may have the same shape as the pulse train.

The first operational amplifier and the second operational amplifier each include an integrating capacitor for integrating the current flowing through the input terminal of the touch input detecting circuit. The output signal of the touch input detecting circuit is input to the first operational amplifier And the second output terminal of the second operational amplifier.

According to another aspect of the present invention, there is provided a touch-chip comprising: a touch input detection circuit connected to a first electrode, the touch input detection circuit being adapted to output a sensing signal for determining whether a touch is inputted to the first electrode; And a stray capacitance compensation circuit (120) adapted to apply a compensation potential following the potential pattern of the first electrode to one or more second electrodes forming a mutual capacitance with the first electrode.

At this time, the potential of the first electrode is controlled by the touch input detection circuit, and information for the control may be provided to the stray capacitance compensation circuit.

The touch input detection circuit includes a first operational amplifier and a second operational amplifier. The first electrode is selectively connected to the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier, Inverting input terminal of the first operational amplifier is applied with a predetermined first reference voltage and a non-inverting input terminal of the second operational amplifier is supplied with a predetermined second reference voltage, A voltage can be applied.

At this time, a timing signal for controlling the on / off state of the switch unit, and information about the first reference voltage and the second reference voltage may be provided to the stray capacitance compensating circuit.

According to the present invention, it is possible to provide a touch input device having a structure for minimizing the influence of mutual capacitance generated between electrodes disposed on a touch panel.

FIG. 1 illustrates an example of an arrangement structure of electrodes disposed on a touch panel according to an embodiment of the present invention.
FIG. 2A illustrates a structure of a touch input detection circuit for measuring a current flowing through electrodes disposed on a touch panel according to an embodiment of the present invention.
FIG. 2B is a timing diagram of each switch of the structure shown in FIG.
FIG. 3 is a view for explaining the reason why mutual capacitance is formed between electrodes having the arrangement structure shown in FIG.
4 is a circuit diagram of a touch input device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein, but may be implemented in various other forms. The terminology used herein is for the purpose of understanding the embodiments and is not intended to limit the scope of the present invention. Also, the singular forms as used below include plural forms unless the phrases expressly have the opposite meaning.

FIG. 1 illustrates an example of an arrangement structure of electrodes disposed on a touch panel according to an embodiment of the present invention.

FIG. 1 (a) illustrates a mutual connection relationship of components included in the touch input device 100 according to an embodiment of the present invention. The touch input device 100 includes first electrodes EC1 to EC9 disposed on the first layer L1, second electrodes ER1 to ER10 disposed on the second layer L2, And a touch-chip 10 connected to the second electrodes ER1 to ER10. The touch chip 10 may be connected to the first electrodes EC1 to EC9 through the first wiring 11 and may be connected to the second electrodes ER1 to ER10 through the second wiring 12. [ Each of the electrodes EC1 to EC9, ER1 to ER10 is insulated from all other electrodes.

FIG. 1 (b) specifically shows the relative arrangement of the first electrodes EC1 to EC9 and the second electrodes ER1 to ER10. The first electrodes EC1 to EC9 are disposed on the first layer L1 and the second electrodes ER1 to ER10 are disposed on the second layer L2 and the first layer L1 and the second layer L2 An insulating layer L3 for insulating the first electrodes EC1 to EC9 from the second electrodes ER1 to ER10 is disposed.

The operation principle according to the first mode of the touch input device 100 according to FIG. 1 can be explained by the following example. For the following description, it is assumed that a touch input is made at a portion where the electrode EC4 and the electrode ER3 intersect.

First, the touch-chip 10 sequentially detects whether or not a capacitance change has occurred with respect to each of the electrodes EC1 to EC9. At this time, since there is no touch input in the electrodes EC1 to EC3 and EC5 to EC9, there is no change in capacitance for the electrodes EC1 to EC3 and EC5 to EC9. However, since the touch input is made to the electrode EC4, a change in capacitance with respect to the electrode EC4 can be sensed. Therefore, the touch-chip 10 can determine that touch input has been made to any of the areas occupied by the electrode EC4.

Then, the touch-chip 10 sequentially detects whether or not a change in capacitance has occurred with respect to each of the electrodes ER1 to ER10. At this time, since there is no touch input in the electrodes ER1 to ER2, ER4 to ER10, there is no change in capacitance for the electrodes ER1 to ER2, ER4 to ER10. However, since a touch input is made to the electrode ER3, a change in capacitance with respect to the electrode ER3 can be sensed.

Therefore, the touch-chip 10 can determine that the touch input is performed at the intersection of the electrode EC4 and the electrode ER3 because the change in capacitance is detected only at the electrode EC4 and the electrode ER3.

Even if the touch input occurs simultaneously at various points on the touch panel, each touch point can be grasped by the same principle as above.

FIG. 2A illustrates a structure of a touch input detection circuit for measuring a current flowing through electrodes disposed on a touch panel according to an embodiment of the present invention.

A plurality of touch input detection circuits 110 shown in FIG. 2A may be provided in the touch-chip 10.

The touch input detection circuit 110 includes an input terminal VIN as an input terminal and may include a first output terminal VOUT1 and a second output terminal VOUT2 as output terminals.

The input terminal VIN may be connected to any one of the electrodes EC1 to EC9 and ER1 to ER10 and may be connected to the reference potential by a switch 81. [ A relative potential difference between the first output terminal VOUT1 and the second output terminal VOUT2 can be provided as an output signal of the touch input detection circuit 110. [

The touch input detection circuit 110 may include a first operational amplifier OA1 and a second operational amplifier OA2.

The first reference voltage VREF_H may be applied to the noninverting input terminal of the first operational amplifier OA1 and the second reference voltage VREF_L may be applied to the non- inverting input terminal of the second operational amplifier OA2 have.

The inverting input terminal of the first operational amplifier OA1 is connected to the input terminal VIN through the switch 61 and can be connected to the first reference voltage VREF_H through the switch 71. [ The inverting input terminal of the second operational amplifier OA2 is connected to the input terminal VIN through the switch 62 and to the second reference voltage VREF_L via the switch 73. [

The output terminal of the first operational amplifier OA1 may be provided as the first output terminal VOUT1 and may be connected to the second reference voltage VREF_L via the switch 72. [ The output terminal of the second operational amplifier OA2 may be provided as the second output terminal VOUT2 and may be connected to the first reference voltage VREF_H via the switch 74. [

The output terminal and the inverting input terminal of the first operational amplifier OA1 may be connected to each other by the first integrating capacitor C _S1 . The output terminal and the inverting input terminal of the second operational amplifier OA2 can be connected to each other by the second integrating capacitor C _S2 .

2A shows any one of the electrodes EC1 to EC9 and ER1 to ER10 shown in Fig. 1, which is an example of the electrode ER4 in Fig. 2A. The capacitance C _SELF represents a sum of the sensing capacitance formed between the touch sensing electrode 101 and the human finger and the floating capacitance formed between the touch sensing electrode 101 and any portion of the user equipment. If the human finger is not present near the touch sensing electrode 101, the value of the sensing capacitance may have a value close to zero, and the value of the capacitance C _SELF may be a value close to the floating capacitance.

2B is a timing chart showing an operation method of the touch input detection circuit 110 shown in FIG. 2A. In FIG. 2B, the horizontal axis represents time.

The signal? _R is a kind of reset signal as a signal for controlling on / off states of the switches 71, 72, 73, 74 and 81.

The signal? ₁ is a signal for controlling the on / off state of the switch 61.

The signal? ₂ is a signal for controlling the on / off state of the switch 62.

When the signal? ₁ , the signal? ₂ and the signal? _R have a high value, the corresponding switch is turned on. When the signal has a low value, .

2B, the signal _VININ indicates the voltage with time of the input terminal _VIN , and the magnitude (ex: VREF_H) of the signal VVIN when the signal? ₁ has a high value, Can be understood by the configuration of the circuit of FIG. 2A in that it is larger than the magnitude (ex: VREF_L) of the signal V _VIN when the signal? ₂ has a high value.

The magnitude of the potential at the first output terminal VOUT1 becomes the second reference voltage VREF_L when reset by the switches 71, 72, 73, 74, And thereafter increases by a certain level every time the rising edge of the signal? ₁ is reached. The rising level may ideally be determined by the ratio of the magnitude of the capacitor C _SELF to the magnitude of the first integral capacitor C _S1 . The reason is that the current flowing through the capacitor C _SELF in the transition period according to the rising edge of the signal? _{1 on} the circuit structure of FIG. 2A flows through the first integrating capacitor C _S1 .

The magnitude of the potential at the second output terminal VOUT2 becomes the first reference voltage VREF_H when reset by the switches 71, 72, 73, 74, And then falls to a certain level every time the rising edge of the signal? ₂ . At this time, the falling level can be ideally determined by the ratio of the magnitude of the capacitor C _SELF to the magnitude of the second integral capacitor C _S2 . This is because the current I _CSELF flowing through the capacitor C _SELF in the transition period according to the rising edge of the signal? _{2 on} the circuit structure of FIG. 2A flows through the second integrating capacitor C _S2 .

If the touch input detection circuit included in the touch-chip 10 can be modeled in the same manner as the touch input detection circuit 110 shown in Fig. 2A, it is possible to ensure the same circuit operation as the design intention of the touch input detection circuit 110 can do. However, since the capacitors C _SELF are not formed in the touch sensing electrode 101 shown in FIG. 2A but different capacitances can be formed, a circuit operation different from the design intention may occur . Hereinafter, the reason why the other capacitance is generated will be described with reference to FIGS. 3A and 3B.

FIG. 3A shows a moment when the capacitance of the electrode ER4 among the touch input devices 100 shown in FIG. 1 is changed. For convenience of explanation, only the electrode ER4 and the electrodes EC1 to EC9 Respectively. At this time, the electrode ER4 has a crossing region 78 intersecting with the electrodes EC1 to EC9. The mutual capacitance can be formed between the electrode ER4 and the electrodes EC1 to EC9 by the intersection region 78, respectively. These mutual capacitances can provide a passage through which current flows. These mutual capacitances correspond to the above-mentioned 'other capacitances'.

FIG. 3B shows an example of modeling the capacitance components formed around the electrode ER4 shown in FIG. 3A.

A capacitance C _SELFR4 may be formed between the electrodes ER4 and other mechanisms 20 such as an LCD included in the user equipment. When an object such as a finger of a person is close to the electrode ER4, a sensing capacitance (C _TOUCH ) may be formed between the finger and the electrode ER4. Here, the sum of the sense capacitance C _TOUCH and the capacitance C _SELFR4 may be referred to as a self capacitance (C _SELF ) 524 formed in the electrode ER4.

And magnetic capacitances C _SELF1 to C _SELF9 may be formed between the other mechanisms 20 and the electrodes EC1 to EC9, respectively. Mutual capacitances C _M1 to C _M9 may be formed between the electrode ER4 and the electrodes EC1 to EC9, respectively. At this time, the magnetic capacitances C _SELF1 to C _SELF9 , the mutual capacitances C _M1 to C _M9 , and the capacitance C _SELFR4 can be defined as the stray capacitance 529 formed in the electrode _ER4 as the touch detection electrode have.

4 illustrates a circuit for applying a voltage to the other electrodes in order to minimize the influence of mutual capacitance formed between the electrodes to be detected and the other electrodes according to an embodiment of the present invention.

Fig. 4 shows a modification of the following three points in the circuit shown in Fig. 2A.

First, the stray capacitance 529 formed around the electrode ER4 is modeled and displayed. The stray capacitance 529 may include the magnetic capacitances C _SELF1 to C _SELF9 , the mutual capacitances C _M1 to C _M9 , and the capacitance C _SELFR4 described with reference to FIG. _3B .

Second, a self capacitance (C _SELF ) 524 formed in the electrode ER4 is divided into a sensing capacitance (C _TOUCH ) and a capacitance (C _SELFR4 ).

Third, a stray capacity compensation circuit 120 for applying the compensation potential to the electrodes EC1 to EC9 is added to minimize the unintended influence of the mutual capacitance.

Current (I _CSELF) also flows into a capacitor (C _SELF) 4 may be of a current (I _CSELF1) that flows from the entering currents (I _CSELF2) and sensing capacitance (C _TOUCH) flowing from the capacitance (C _SELFR4) .

By the capacitor (C _SELF) current (I _CSELF) flowing into the touch input current input to the detection circuit (110) _(I I) and the mutual capacitance (C _M1, C _M2, ... _M9 C) It flows into a path that is formed may be branched to a leakage current _{(I L = I L1 + I} L2 + ... + I L9). At this time, if the value of the leakage current I _L can be minimized, the touch input detection circuit 110 can be operated in substantially the same manner as the design.

A method may be used in which the potential difference between both electrodes constituting the mutual capacitances C _M1 , C _M2 , ... C _M9 is made zero or minimized in order to minimize the value of the leakage current I _L. For example, when the potential difference between the 'both electrodes' constituting the mutual capacitances C _M1 , C _M2 , ... C _M9 is 0, a current can flow through the mutual capacitances C _M1 , C _M2 , ... C _M9 none. At this time, the first electrode of the 'both electrodes' is the electrode ER4 which is the touch detecting electrode, and the second electrode is the other electrodes EC1 to EC9. Therefore, in one embodiment of the present invention, the difference in potential between the electrode ER4 and the electrodes EC1 to EC9 is minimized. Since the electrode ER4 corresponds to the touch sensing electrode 101 of FIG. 2B, the magnitude of the potential of the electrode ER4 may have the same value as the magnitude of the signal V _VIN of FIG. 2B. Therefore, when a potential following the signal V _VIN of FIG. 2B is applied to the electrodes EC1 through EC9, the difference in potential between the electrode ER4 and the electrodes EC1 through EC9 can be minimized. Here, the " following potential " refers to a potential having the same waveform as the signal (V _VIN ), or the same or similar potential pattern of potential change with time. Preferably, a potential having the same magnitude as the signal (V _VIN ) in Fig. 2B can be applied to the electrodes EC1 to EC9 as the potential to be followed.

The stray capacitance compensation circuit 120 is a circuit provided to apply the potential following the signal (V _VIN ) of Fig. 2B to the electrodes EC1 to EC9. The stray capacitance compensation circuit 120 may include an amplifier 300 and a switch unit 400. [ The output terminal of the amplifier 300 may be connected to the electrodes EC1 to EC9. At this time, the voltage VS at the output terminal of the amplifier 300 may be designed to follow a time-dependent variation pattern of the signal V _VIN of FIG. 2B. The input terminal 301 of the amplifier 300 may be connected to the first compensation potential VRH by the first switch SWH and to the second compensation potential VRL by the second switch SWL . The first compensation potential VRH may be equal to, for example, the first reference voltage VREF_H and the second compensation potential VRL may be equal to, for example, the second reference voltage VREF_L. Or the first compensation potential VRH has a voltage VREF_H 'similar to the first reference voltage VREF_H and the second compensation potential VRL has a voltage VREF_L' similar to the second reference voltage VREF_L (Where VREF_H '>VREF_L').

The first switch SWH and the second switch SWL are not turned on at the switch unit 400 at the same time. For example, the first control signal? ₃ for controlling ON / OFF of the first switch SWH may have the same pattern as the signal? ₁ of FIG. 2B, and the ON / OFF state of the second switch SWL The second control signal? _{4 to be} controlled may have the same pattern as the signal? ₂ of FIG. 2B.

4, the electrodes EC1 to EC9 are connected to the stray capacitance compensating circuit 120, but at other points, the electrodes EC1 to EC9 may be connected to the stray capacitance compensating circuit 120, respectively, . A circuit element such as a switch or a mux can be used for such circuit switching, but the illustration is omitted in Fig.

4 shows an example of a moment at which the change in capacitance of the electrode ER4 is measured. However, it can be easily understood that the instant at which the change in the capacitance of the other electrode is measured can also have a circuit configuration similar to that in Fig. For example, only the electrode ER4 shown in Fig. 4 can be changed to the corresponding electrode at the moment of measuring the change in the capacitance of any one of the electrodes ER1 to ER3 and ER5 to ER10. 4 is replaced with a corresponding electrode, and the electrodes EC1 to EC9 shown in Fig. 4 are connected to the electrodes ER1, EC2, (ER1 to ER10).

Although an example in which a plurality of electrodes are arranged in two layers is shown in this specification, even when the electrodes are disposed on all the electrodes in one layer as in a pattern disclosed in Korean Patent Laid-open Publication No. 10-2014-0044720, Can be applied.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the essential characteristics thereof. The contents of each claim in the claims may be combined with other claims without departing from the scope of the claims.

10: Touch-chip
100: Touch input device
110: Touch input detection circuit
120: Stray capacitance compensation circuit
ER1 to ER10, EC1 to EC9: Electrodes
11, 12: Wiring
L1: first layer
L2: Second layer
L3: Transparent insulation layer
OA1, OA2: Operational amplifier
300: amplifier

Claims (12)

A touch input detection circuit;
A first electrode for detecting whether the touch input is detected by the touch input detection circuit and whose potential is controlled by the touch input detection circuit;
At least one second electrode that forms a mutual capacitance with the first electrode; And
A stray capacitance compensation circuit adapted to apply a compensation potential following the potential pattern of the first electrode to the second electrode;
/ RTI >
Touch input device. The method according to claim 1,
Wherein the first electrode extends along a first direction on a touch panel included in the touch input device,
The second electrode extends along a second direction different from the first direction on the touch panel,
Wherein the first electrode and the second electrode are insulated from each other,
Wherein a crossing region exists between the first electrode and the second electrode,
Touch input device. The method according to claim 1,
Wherein the touch input detection circuit includes a first operational amplifier and a second operational amplifier,
The first electrode is selectively connected to the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier,
A first reference voltage is applied to a non-inverting input terminal of the first operational amplifier,
And a second reference voltage is applied to a non-inverting input terminal of the second operational amplifier,
Touch input device. The method of claim 3,
Wherein the stray capacitance compensation circuit includes an operational amplifier and a switch section for supplying an input voltage to the operational amplifier,
Wherein the output terminal of the operational amplifier is coupled to the second electrode to provide the compensation potential,
Wherein the switch unit is configured to supply the first reference voltage to an input terminal of the operational amplifier when the first electrode is connected to the first operational amplifier and when the first electrode is connected to the second operational amplifier, And to supply the second reference voltage to an input terminal of the amplifier,
Touch input device. The method of claim 3,
Wherein the potential of the first electrode has a pattern of a pulse train for switching between the first reference voltage and the second reference voltage,
Wherein the compensation potential has the same time variation pattern as the pulse train,
Touch input device. 6. The method of claim 5, wherein the compensation potential has the same form as the pulse train. Touch input device. The method of claim 3,
The first operational amplifier and the second operational amplifier each include an integrating capacitor for integrating a current flowing through an input terminal of the touch input detecting circuit,
Wherein an output signal of the touch input detection circuit is provided as a potential difference between a first output terminal of the first operational amplifier and a second output terminal of the second operational amplifier,
Touch input device. A touch input detection circuit coupled to the first electrode and configured to output a sensing signal for determining whether the first electrode is touch input; And
And a compensation capacitor for compensating for a potential pattern of the first electrode to one or more second electrodes forming a mutual capacitance with the first electrode,
/ RTI >
Touch-chip. 9. The touch-chip of claim 8, wherein the potential of the first electrode is controlled by the touch input detection circuit, and information for the control is provided to the stray capacitance compensation circuit. 9. The method of claim 8,
Wherein the touch input detection circuit includes a first operational amplifier and a second operational amplifier,
And a switch unit for selectively connecting the first electrode to the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier,
A first reference voltage is applied to a non-inverting input terminal of the first operational amplifier,
And a second reference voltage is applied to a non-inverting input terminal of the second operational amplifier,
Touch-chip. 11. The method of claim 10,
Wherein the stray capacitance compensation circuit includes an operational amplifier and a switch section for supplying an input voltage to the operational amplifier,
Wherein the output terminal of the operational amplifier is coupled to the second electrode to provide the compensation potential,
Wherein the switch unit is configured to supply the first reference voltage to an input terminal of the operational amplifier when the first electrode is connected to the first operational amplifier and when the first electrode is connected to the second operational amplifier, And to supply the second reference voltage to an input terminal of the amplifier,
Touch-chip. 11. The touch-chip of claim 10, wherein a timing signal for controlling the on / off state of the switch section and information on the first reference voltage and the second reference voltage are provided to the stray capacitance compensation circuit.

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