CN112394846B - Touch input detection device - Google Patents

Touch input detection device Download PDF

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Publication number
CN112394846B
CN112394846B CN201911130417.9A CN201911130417A CN112394846B CN 112394846 B CN112394846 B CN 112394846B CN 201911130417 A CN201911130417 A CN 201911130417A CN 112394846 B CN112394846 B CN 112394846B
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Prior art keywords
operational amplifier
electrode
capacitance
output voltage
touch input
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CN112394846A (en
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金福万
苏柄喆
金亨俊
尹泰贤
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Zinitix Co Ltd
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Zinitix Co Ltd
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/96—Touch switches
    • H03K17/962—Capacitive touch switches
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
    • H03K2217/94—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00 characterised by the way in which the control signal is generated
    • H03K2217/96—Touch switches
    • H03K2217/9607—Capacitive touch switches
    • H03K2217/96071—Capacitive touch switches characterised by the detection principle

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Input By Displaying (AREA)
  • Electronic Switches (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

Disclosed is a touch input detection device including: a first operational amplifier; a second operational amplifier; a switching unit for selectively connecting a sense electrode to only one of an inverting input terminal of the first operational amplifier and an inverting input terminal of the second operational amplifier; a driving unit for applying a pulse sequence signal to a driving electrode (TX) forming a mutual capacitance with the sensing electrode, so that the potential of the driving electrode changes in synchronization with the state change of the switching unit; a control unit that controls operation of the switching unit such that a difference value obtained by subtracting the second output voltage of the second operational amplifier from the first output voltage of the first operational amplifier is gradually reduced in a first time period, and the difference value is gradually increased in a second time period; and a capacitance measuring unit that measures a capacitance formed at the sense electrode based on a first difference value that is the difference value obtained in the first time interval and a second difference value that is the difference value obtained in the second time interval.

Description

Touch input detection device
Technical Field
The present invention relates to a touch input detection device, and relates to a technique capable of obtaining a mutual capacitance and a self capacitance formed at a measurement target electrode.
Background
Touch screen panels (Touch SCREEN PANEL) are used in a large number of smart phones, displays, TVs, keyboards, cameras, etc. The touch screen panel is an input device that recognizes the position of a user if the user presses or touches a screen with a finger, a pen, or the like, and transmits the position to the system. Touch screen panels are classified into a resistive film type, a capacitive type, and the like according to application techniques.
The capacitive mode may be roughly divided into a mutual capacitive mode and a self-capacitive mode.
The mutual capacitance method is a method of measuring a mutual capacitance correlation value formed between a sense electrode and a drive electrode to be measured by applying a voltage having a predetermined time pattern to the drive electrode capacitively coupled to the sense electrode. As a related art using a mutual capacitance method, there is korean registered patent "KR 10-1169253" (hereinafter referred to as prior art 1).
The self-capacitance method is a method of measuring a capacitance component correlation value formed in a sensing electrode by changing the potential of the sensing electrode to be measured at a predetermined level and measuring a charge amount correlation value moved from the sensing electrode at this time. As a related art using the self-capacitance method, there is korean published patent "KR 10-2016-0006982" (hereinafter referred to as prior art 2).
Prior art 1 is a technology relating to an integrating circuit combined with an inverting integrating circuit and a non-inverting integrating circuit. The integrating circuit comprises a first operational amplifier, a second operational amplifier and a capacitor. Fig. 1 is one of the drawings presented in prior art 1. Referring to fig. 1, a pulse sequence signal for changing the potential of the driving electrode is applied to measure the correlation value of the mutual capacitance Cij between the driving electrode and the sensing electrode. At this time, the non-inverting terminals of both operational amplifiers have the same potential. The driving electrode may be an electrode to which the pulse sequence signal designed in advance is applied to an electrode forming a capacitor with the sensing electrode connected to the capacitance component detection circuit.
Prior art 2 is a technology related to an electrostatic touch input device having a stray capacitance compensation circuit. The touch chip of prior art 2 includes a touch input detection circuit and a compensation circuit, and an input terminal of the touch input detection circuit and an output terminal of the compensation circuit are connected to a touch input sensing electrode. Fig. 2 is one of the drawings presented in prior art 2. In prior art 2, in order to measure the self-capacitance correlation value formed at the sense electrode ER4, mutually different potentials vref_ H, VREF _l are applied to the non-inverting terminals of the two operational amplifiers OA1, OA 2. In prior art 2, in measuring the self-capacitance correlation value formed at the sense electrode, a pulse sequence signal is not connected to the other electrode forming a capacitance with the sense electrode.
Disclosure of Invention
The present invention aims to provide a technology capable of obtaining a mutual capacitance which is a capacitance formed between a driving electrode which is capacitively coupled with a sensing electrode which is a measurement object and the sensing electrode, and a self capacitance which is a capacitance component other than the mutual capacitance in the capacitance formed by the sensing electrode.
According to one aspect of the present invention, the potential of the driving electrode capacitively coupled to the sensing electrode to be measured can be changed in synchronization with the potential of the sensing electrode. The potential of the driving electrode may be changed to a predetermined first mode during a first time period and a second time period, and the potential of the sensing electrode may be changed to a predetermined second mode during the first time period and the second time period. The first phase difference, which is a phase difference between the potential of the driving electrode and the potential of the sensing electrode in the first time interval, may be different from the second phase difference, which is a phase difference between the potential of the driving electrode and the potential of the sensing electrode in the second time interval. And calculating the mutual capacitance between the driving electrode and the sensing electrode by mutually calculating the first measurement value related to the capacitance of the sensing electrode measured in the first time interval and the second measurement value related to the capacitance of the sensing electrode measured in the second time interval. Further, the first measurement value and the second measurement value are calculated with each other, whereby a self-capacitance, which is a capacitance other than the mutual capacitance among capacitances formed by the sense electrodes, can be calculated. That is, according to an aspect of the present invention, the mutual capacitance and the self-capacitance can be all calculated.
The touch input detection device of one aspect of the present invention may include: a first operational amplifier OA1; a second operational amplifier OA2; a switching unit 20, Φ1, Φ2 for selectively connecting the sense electrode RX to only one of the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier; a driving unit 10 for applying a signal having a predetermined pattern to a driving electrode TX forming a mutual capacitance with the sensing electrode, and changing the potential of the driving electrode in synchronization with the state change of the switching unit; a control unit 30 that controls the operation of the switching unit such that a difference VOUT obtained by subtracting the second output voltage of the second operational amplifier from the first output voltage of the first operational amplifier is gradually reduced in a first time period, and the difference VOUT is gradually increased in a second time period; and a capacitance measuring unit 40 that measures a capacitance-related value formed at the sense electrode based on a first difference value VOUT121 that is the difference value obtained in the first time period and a second difference value VOUT122 that is the difference value obtained in the second time period.
In this case, a first reference voltage may be applied to the non-inverting input terminal of the first operational amplifier, and a second reference voltage different from the first reference voltage may be applied to the non-inverting input terminal of the second operational amplifier.
In this case, the capacitance measuring unit may measure the self capacitance formed by the sense electrode and the circuit element other than the drive electrode based on a value obtained by adding the first difference value and the second difference value.
At this time, the capacitance measuring section may measure the mutual capacitance based on a value obtained by subtracting the first difference value from the second difference value.
In this case, a capacitor is connected between the inverting input terminal and the output terminal of any one of the first and second operational amplifiers, and if the sensing electrode and the inverting input terminal of the any one of the operational amplifiers are connected to each other in accordance with the operation of the switching unit, the voltage across the capacitor can be changed by the charge that moves through the sensing electrode.
In this case, the control unit may control the operation of the switching unit such that the first output voltage is gradually decreased and the second output voltage is gradually increased during the first time period, and the first output voltage is gradually increased and the second output voltage is gradually decreased during the second time period.
At this time, it may further include: a first capacitor connected between an inverting input terminal and an output terminal of the first operational amplifier; and a second capacitor connected between the inverting input terminal and the output terminal of the second operational amplifier; the control section may control the switching section such that the output value of the first operational amplifier is changed before the output value of the second operational amplifier after resetting the first capacitor and the second capacitor in the first time period, and the output value of the second operational amplifier is changed before the output value of the first operational amplifier after resetting the first capacitor and the second capacitor in the second time period.
At this time, the potential of the sensing electrode may be changed in synchronization with the state change of the switching section.
The touch input detection device of another aspect of the present invention may include: a first operational amplifier OA1; a switch unit 20 for connecting the sense electrode RX to the inverting input terminal of the first operational amplifier; a driving unit 10 for applying a signal having a predetermined pattern to a driving electrode TX forming a mutual capacitance with the sensing electrode, and changing the potential of the driving electrode in synchronization with the state change of the switching unit; a control unit 30 that controls the operation of the switching unit such that the first output voltage VOUT1 of the first operational amplifier is gradually decreased in a first time period, and the first output voltage VOUT1 is gradually increased in a second time period; and a capacitance measuring unit 40 that measures a capacitance formed at the sense electrode based on the first output voltage VOUT1 obtained during the first time period and the first output voltage VOUT1 obtained during the second time period.
At this time, the potential of the sensing electrode may be changed in synchronization with the state change of the switching section.
At this time, the switching unit 20 may include a first switch Φ1 and a second switch Φ2, and the first reference voltage and the second reference voltage may be alternately applied to the sensing electrode RX by the first switch Φ1 and the second switch Φ2.
At this time, the capacitance measuring unit may measure the self capacitance formed by the sense electrode and the circuit element other than the drive electrode based on a value obtained by adding the first output voltage VOUT1 obtained in the first time period and the first output voltage VOUT1 obtained in the second time period.
At this time, the capacitance measuring section may measure the mutual capacitance based on a value obtained by subtracting the first output voltage VOUT1 obtained in the first time interval from the first output voltage VOUT1 obtained in the second time interval.
The user equipment according to one aspect of the present invention may include: the user input device comprises a sensing electrode and a driving electrode; the touch input detection device; and a main processing device which receives the capacitance correlation value formed at the sensing electrode measured by the touch input detecting device from the touch input detecting device.
According to the present invention, a predetermined voltage pattern is applied to a driving electrode capacitively coupled to a sensing electrode to be measured, and a capacitance correlation value formed at the sensing electrode is measured, and thus, the capacitance correlation values of the sensing electrode measured in two different time intervals are calculated with each other, whereby a technique is provided in which a mutual capacitance, which is a capacitance formed between the driving electrode and the sensing electrode, and a self capacitance, which is a capacitance component other than the mutual capacitance, among capacitances formed at the sensing electrode, can be obtained.
Drawings
FIG. 1 shows the construction of a touch sensing circuit of one embodiment.
Fig. 2 shows the configuration of a touch sensing circuit of another embodiment.
Fig. 3 is a diagram for explaining a touch input detecting apparatus according to an embodiment of the present invention.
Fig. 4a is a diagram illustrating the intervals T2 to T3 in the first time interval according to one embodiment of the present invention, and fig. 4b is a diagram illustrating the intervals T3 to T4 in the first time interval according to one embodiment of the present invention.
Fig. 5 is a timing diagram showing states of nodes at different times in a first time interval according to one embodiment of the present invention.
Fig. 6a is a diagram for illustrating the intervals T2 to T3 in the second time interval according to one embodiment of the present invention, and fig. 6b is a diagram for illustrating the intervals T3 to T4 in the second time interval according to one embodiment of the present invention.
Fig. 7 is a timing diagram showing states of nodes at different times in a second time interval according to one embodiment of the present invention.
Fig. 8 shows an example of the configuration of a touch input detection device according to another embodiment of the present invention.
Fig. 9 is a diagram showing the constitution of a user equipment according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention are described below with reference to the accompanying drawings. The present invention is not limited to the embodiments described in the present specification, but may be embodied in various forms. The terminology used in the description is for the purpose of aiding in the understanding of the embodiments and is not intended to limit the scope of the present invention. The singular forms used hereinafter also include the plural forms, unless the phrase clearly indicates the contrary.
Fig. 3 is a diagram for explaining a touch input detecting apparatus according to an embodiment of the present invention.
The touch input detection device may include a first operational amplifier OA1, a second operational amplifier OA2, a switching section 20, Φ1, Φ2, a driving section 10, a control section 30, and a capacitance measuring section 40.
The touch input detection device may not include the sensing electrode RX, the driving electrode TX and other circuit elements not shown, among the circuit elements shown in fig. 3, which are formed from the capacitor CSELF. The touch input detection device may also be provided in the form of a packaged chip.
A first capacitor CS1 may be connected between the inverting input terminal (-) and the output terminal of the first operational amplifier OA 1. A switch Φr may be connected between the inverting input terminal (-) and the output terminal of the first operational amplifier OA 1. The first reference voltage VREF1 may be applied to the non-inverting input terminal (+) of the first operational amplifier OA 1.
A second capacitor CS2 may be connected between the inverting input terminal (-) and the output terminal of the second operational amplifier OA 2. Further, a switch Φr may be connected between the inverting input terminal (-) and the output terminal of the second operational amplifier OA 2. The second reference voltage VREF2 may be applied to the non-inverting input terminal (+) of the second operational amplifier OA 2.
The size of the first capacitor CS1 and the size of the second capacitor CS2 may be the same as each other.
At this time, the first reference voltage VREF1 and the second reference voltage VREF2 may be supplied by the VREF voltage varying unit 50, and the operation of the VREF voltage varying unit 50 may be controlled by a VREF control signal.
In one embodiment of the present invention, the first reference voltage VREF1 and the second reference voltage VREF2 have different values from each other.
The switching section 20 may include a first switch Φ1 and a second switch Φ2. The switching unit 20 may selectively connect the sense electrode RX to only one of the inverting input terminal (-) of the first operational amplifier OA1 and the inverting input terminal (-) of the second operational amplifier OA 2.
That is, the switching section 20 may turn on the first switch Φ1 and turn off the second switch Φ2 so that the sense electrode RX is connected only to the inverting input terminal of the first operational amplifier OA 1. Conversely, the switching section 20 may turn off the first switch Φ1 and turn on the second switch Φ2 so that the sense electrode RX is connected only to the inverting input terminal of the second operational amplifier OA 2.
At this time, if the inverting input terminal of any one of the first and second operational amplifiers is connected to the sense electrode RX according to the operation of the switching unit 20, the voltage across the capacitor CS1 or CS2 can be changed by the charge that moves through the sense electrode RX. The principle of operation of such a circuit has been substantially proposed in the prior art described above.
The driving section 10 may include a T1 switch Φt1 and a T2 switch Φt2. One terminal of the T1 switch Φt1 may be connected to the VDD potential, and the other terminal may be connected to one terminal of the T2 switch Φt2 and the driving electrode TX. The other terminal of the T2 switch Φt2 may be connected to the GND potential. The VDD potential and the GND potential may be referred to as a first driving potential and a second driving potential, respectively, and are not limited to VDD and GND. However, preferred values of the first driving potential and the second driving potential may be the VDD and GND.
The driving unit 10 has a structure including a T1 switch Φt1 and a T2 switch Φt2, and this is to apply a pulse sequence signal to the driving electrode TX, and if this is achieved, the driving unit 10 may have another structure. That is, an equivalent structure of the driving unit 10 can be proposed.
The driving unit 10 may apply a pulse sequence signal to the driving electrode TX forming a mutual capacitance with the sensing electrode RX, so that the potential of the driving electrode TX changes in synchronization with the state change of the switching unit 20. Here, the potential of the driving electrode TX is synchronized with the state change of the switching section 20, which has been fully exemplified in the prior art 1, and can be easily understood from fig. 5 (c), (d), and (e) and fig. 7 (c), (d), and (e) of the present specification.
The control unit 30 may control the operation of the switching unit 20 such that a difference VOUT obtained by subtracting the second output voltage of the second operational amplifier OA2 from the first output voltage of the first operational amplifier OA1 is gradually decreased in a first time period, and the difference VOUT is gradually increased in a second time period.
The first time interval may be, for example, a time interval shown in fig. 5 of the present specification, and the second time interval may be, for example, a time interval shown in fig. 7 of the present specification.
The capacitance measuring section 40 may measure the capacitance-related value formed at the sense electrode RX based on a first difference value VOUT12 1 as the difference value obtained in the first time interval and a second difference value VOUT12 2 as the difference value obtained in the second time interval. The capacitance formed at the sensing electrode RX may be composed of a mutual capacitance formed between the sensing electrode RX and the driving electrode TX and a self capacitance which is a capacitance other than the mutual capacitance among the capacitances formed at the sensing electrode RX.
The capacitance correlation value formed at the sensing electrode RX may be provided according to the output voltage of the first operational amplifier OA1 and the output voltage of the second operational amplifier OA 2.
FIG. 4a is a diagram illustrating the operation of the circuit of the intervals T2-T3 of FIG. 5 in a first time interval according to one embodiment of the present invention, and FIG. 4b is a diagram illustrating the operation of the circuit of the intervals T3-T4 of FIG. 5 in a first time interval according to one embodiment of the present invention.
Fig. 5 is a timing diagram showing states of nodes at different times in a first time interval according to one embodiment of the present invention.
Fig. 5 (a) shows output values of the first operational amplifier OA1 and the second operational amplifier OA2 at different times, fig. 5 (b) to 5 (d) show on-off timings of the switch Φr, the switch Φ2, and the switch Φ1 at different times, and fig. 5 (e) and 5 (f) show potentials of the driving electrode TX and the sensing electrode RX at different times, respectively.
If examining the circuits shown in fig. 5 (e) and (f) and fig. 4a, it can be understood that the potential of the driving electrode TX is controlled in a pulse train, and the potential of the sensing electrode RX is also controlled in a pulse train.
The operation in the first time interval will be described with reference to fig. 4a, 4b and 5.
First, the first capacitor CS1 and the second capacitor CS2 may be reset in a first time interval. Then, the control unit 30 may control the switching unit 20 to change the output value VOUT1 of the first operational amplifier OA1 before the output value VOUT2 of the second operational amplifier OA 2.
That is, by turning on the switch Φr, the first capacitor CS1 and the second capacitor CS2 can be reset. Then, in the time interval T2 to T3 of the first time interval, the first switch Φ1 connected to the first operational amplifier OA1 is turned on, and the second switch Φ2 connected to the second operational amplifier OA2 is turned off by the control unit. Then, in the time interval T3 to T4 of the first time interval, the first switch Φ1 connected to the first operational amplifier OA1 may be turned off, and the second switch Φ2 connected to the second operational amplifier OA2 may be turned on.
At this time, the first reference voltage VH may be applied to the non-inverting terminal of the first operational amplifier OA1, and the second reference voltage VL different from the first reference voltage may be applied to the non-inverting terminal of the second operational amplifier OA 2.
In a preferred embodiment, the first reference voltage VH may be greater than the second reference voltage VL.
In the time interval T2 to T3, the current flowing into the first capacitor CS1 may be an inversion current of the mutual capacitance between the driving electrode TX and the sensing electrode RX and a charging current of the self-capacitance of the sensing electrode RX.
In the time interval T3 to T4, the current flowing into the second capacitor CS2 is the charge current of the mutual capacitance between the driving electrode TX and the sensing electrode RX and the discharge current of the self capacitance of the sensing electrode RX.
In the first time interval, according to the operation, the first output voltage VOUT1 of the first operational amplifier OA1 may gradually decrease, and the second output voltage VOUT2 of the second operational amplifier OA2 may gradually increase.
At this time, the following equations 1 to 4 may be satisfied.
At this time, in the first time interval, the first difference VOUT12 1 of the second output voltage of the second operational amplifier is subtracted from the first output voltage VOUT1 of the first operational amplifier as shown in the following equation 2.
[ Number 1]
CS = CS1 = CS2，
△VR = VH-VL，
CM: mutual capacitance between driving electrode TX and sensing electrode RX
U: number of charge-discharge repetition times
[ Number 2]
VOUT121 = - U × [ CM × （VDD - △VR） - （CSELF × △VR） ] / CS + △VR
= - VOUT（MUTUAL） + VOUT（SELF） + △VR
[ Number 3]
VOUT（MUTUAL） = U × （CM × VDD） / CS
[ Number 4]
VOUT（SELF） = U × [ （CM × △VR） + （CSELF × △VR） ] / CS
The first difference VOUT12 1 is configured as shown in equation 2, and includes VOUT (setup) which is a component reflecting the MUTUAL capacitance effect and VOUT (SELF) which is a component reflecting the SELF capacitance effect.
FIG. 6a is a diagram illustrating the operation of the circuit for intervals T2-T3 in the second time interval according to one embodiment of the invention, and FIG. 6b is a diagram illustrating the operation of the circuit for intervals T3-T4 in the second time interval according to one embodiment of the invention.
Fig. 7 is a timing diagram showing states of nodes at different times in a second time interval according to one embodiment of the present invention.
Fig. 7 (a) shows output values of the first operational amplifier OA1 and the second operational amplifier OA2 at different times, fig. 7 (b) to 7 (d) show on-off timings of the switch Φr, the switch Φ2, and the switch Φ1 at different times, and fig. 7 (e) and 7 (f) show potentials of the driving electrode TX and the sensing electrode RX at different times, respectively.
Comparing fig. 7 (c) and (d) with fig. 5 (c) and (d), it can be confirmed that the operation order of the first switch Φ1 and the second switch Φ2 is reverse.
The operation in the second time zone will be described with reference to fig. 6a, 6b and 7.
As described above, the first time period may be, for example, a time period shown in fig. 5 of the present specification, and the second time period may be, for example, a time period shown in fig. 7 of the present specification.
If examining the circuits shown in fig. 7 (e) and (f) and fig. 6a, it can be understood that the potential of the driving electrode TX is controlled in a pulse train, and the potential of the sensing electrode RX is also controlled in a pulse train.
According to fig. 5 (e) and (f), the potential of the driving electrode TX and the potential of the sensing electrode RX are in phase with each other, but according to fig. 7 (e) and (f), it can be confirmed that the potential of the driving electrode TX and the potential of the sensing electrode RX are in inverse phase with each other.
First, in a second time interval, the first capacitor CS1 and the second capacitor CS2 may be reset. After the reset is performed, the switching unit 20 may be controlled so that the output value of the second operational amplifier OA2 is changed before the output value of the first operational amplifier OA 1.
That is, the first capacitor CS1 and the second capacitor CS2 may be reset by the switch Φr. Then, in the time interval T2 to T3 of the second time interval, the second switch Φ2 connected to the second operational amplifier OA2 may be turned on, and the first switch Φ1 connected to the first operational amplifier OA1 may be turned off by the control unit. Then, in the time interval T3 to T4 of the second time interval, the second switch Φ2 connected to the second operational amplifier OA2 may be turned off, and the first switch Φ1 connected to the first operational amplifier OA1 may be turned on.
At this time, the first reference voltage VH may be applied to the non-inverting terminal of the first operational amplifier OA1, and the second reference voltage VL different from the first reference voltage may be applied to the non-inverting terminal of the second operational amplifier OA 2.
At this time, the first reference voltage VH in the first time interval and the first reference voltage VH in the second time interval may have the same value as each other, and the second reference voltage VL in the first time interval and the second reference voltage VL in the second time interval may have the same value as each other.
In the time interval T2 to T3, the current flowing into the second capacitor CS2 is the discharge current of the mutual capacitance between the driving electrode TX and the sensing electrode RX and the discharge current of the self capacitance of the sensing electrode RX.
In the time interval T3-T4, the current flowing into the first capacitor CS1 is the charging current of the mutual capacitance between the driving electrode TX and the sensing electrode RX and the charging current of the self-capacitance of the sensing electrode RX.
In the second time interval, according to the operation, the first output voltage VOUT1 of the first operational amplifier OA1 may gradually increase, and the second output voltage VOUT2 of the second operational amplifier OA2 may gradually decrease.
In this case, the above equations 1, 3 and 4 can be similarly established, and equation 5 regarding the second difference VOUT12 2 between the first output voltage and the second output voltage can be as follows.
[ Number 5]
VOUT122 = U × [ CM × VDD + △VR + CSELF × △VR ] / CS + △VR
= VOUT（MUTUAL） + VOUT（SELF） + △VR
The second difference VOUT12 2 is configured to include VOUT (mutu) as a component reflecting the MUTUAL capacitance effect and VOUT (SELF) as a component reflecting the SELF capacitance effect, as shown in equation 5.
At this time, a capacitance-related value formed at the sense electrode RX may be measured based on the first difference value VOUT12 1 obtained in the first time interval 1 and the second difference value VOUT12 2 obtained in the second time interval.
That is, the capacitance measuring unit 40 may measure the self-capacitance correlation value formed by the sense electrode RX and the circuit elements other than the drive electrode TX based on the value obtained by adding the first difference value VOUT12 1 and the second difference value VOUT12 2. Equation 6 regarding this can be as follows.
[ Number 6]
VOUT121 + VOUT122 = 2 × VOUT（SELF） + 2 × △VR
In addition, the capacitance measuring unit 40 may measure a mutual capacitance correlation value between the driving electrode TX and the sensing electrode RX based on a value obtained by subtracting the first difference value VOUT12 1 from the second difference value VOUT12 2. Equation 7 regarding this can be as follows.
[ Number 7]
VOUT122 - VOUT121 = 2 × VOUT（MUTUAL）
If equation 4 is referred to, when the non-inverting terminals of the two operational amplifiers are set to have the same potential as each other and Δvr is 0 as in the above-described prior art 1, VOUT (SELF) is 0, and the influence of the SELF-capacitance is not reflected in the first difference VOUT12 1 and the second difference VOUT12 2.
However, if the non-inverting terminals of the two operational amplifiers have different potentials (i.e., vh+.vl) and Δvr is a value other than 0, VOUT (SELF) is a value other than 0, and the influence of SELF capacitance is reflected in the first difference VOUT12 1 and the second difference VOUT12 2.
The above-described embodiments of the present invention are embodiments configured such that the non-inverting terminals of two operational amplifiers have mutually different potentials. In the case of the above-described embodiment, that is, in the case where the self-capacitance and the mutual capacitance coexist, the configuration of the capacitance measuring section 40 has an effect that the influence of the self-capacitance can be eliminated when only the mutual capacitance correlation value is to be measured.
In addition, as described above, the pulse sequence signal is applied to the driving electrode TX. That is, VDD has a value other than 0. In the above-described prior art 2, the "other electrode" may be referred to as having a floating state or the case where VDD has a value of 0.
In the case where VDD has a value of 0 as in prior art 2, VOUT (mutu) of equation 3 is 0, and the influence of the MUTUAL capacitance is not reflected in the first difference VOUT12 1 and the second difference VOUT12 2.
However, as shown in the embodiment, in the case where VDD has a value other than 0, VOUT (mutu) has a value other than 0, and the influence of MUTUAL capacitance is reflected in the first difference VOUT12 1 and the second difference VOUT12 2.
The present invention has an effect of eliminating the influence of the mutual capacitance when only the self-capacitance correlation value is to be measured by the function of the capacitance measuring section 40 in the case of switching in the pulse sequence signal to the driving electrode TX, that is, in the case where the self-capacitance and the mutual capacitance coexist.
Fig. 8 shows a configuration example of a touch input detection apparatus according to another embodiment of the present invention.
The touch input detection device shown in fig. 8 is a circuit in which the second operational amplifier OA2 and a circuit element coupled between the inverting input terminal and the output terminal of the second operational amplifier OA2 are removed in the touch input detection device shown in fig. 3. The capacitance measuring unit 40 of the touch input detection device shown in fig. 8 may accept the output voltage VOUT1 of the first operational amplifier OA1 as an input. In contrast, the capacitance measuring unit 40 of the touch input detection device shown in fig. 3 may accept as input a difference value between the output voltage VOUT1 of the first operational amplifier OA1 and the output voltage VOUT2 of the second operational amplifier OA 2.
The touch input detection device shown in fig. 8 may include: a first operational amplifier OA1; a switch unit 20 for connecting the sense electrode RX to the inverting input terminal of the first operational amplifier OA1; a driving unit 10 for applying a signal having a predetermined pattern to a driving electrode TX forming a mutual capacitance with the sensing electrode RX, and changing the potential of the driving electrode TX in synchronization with the state change of the switching unit 20; a control unit 30 that controls the operation of the switching unit 20 such that the first output voltage VOUT1 of the first operational amplifier is gradually decreased in a first time period, and the first output voltage VOUT1 is gradually increased in a second time period; and may be such that the capacitance formed at the sense electrode RX is measured based on the first output voltage VOUT1 obtained in the first time interval and the first output voltage VOUT1 obtained in the second time interval.
At this time, the potential of the sensing electrode RX may be changed in synchronization with the state change of the switching section 20.
At this time, the switching unit 20 may include a first switch Φ1 and a second switch Φ2. Further, the first reference voltage and the second reference voltage may be alternately applied to the sensing electrode RX by means of the first switch Φ1 and the second switch Φ2.
For example, the first switch Φ1 may connect the sensing electrode RX to the inverting input terminal of the first operational amplifier OA1, and at this time, the first reference voltage may be applied to the non-inverting input terminal of the first operational amplifier OA 1. Also, the second switch Φ2 may connect the sensing electrode RX to a node having a second reference voltage. At this time, the second reference voltage may be supplied by means of a predetermined circuit included in the touch input detection device, for example, by means of the VREF voltage fluctuation section 50.
At this time, the capacitance measuring section 40 may measure an auto-capacitance correlation value formed by the sense electrode RX and other circuit elements than the drive electrode TX based on a value obtained by adding the first output voltage VOUT1 obtained in the first time period and the first output voltage VOUT1 obtained in the second time period.
At this time, the capacitance measuring section 40 may measure the mutual capacitance based on subtracting the value of the first output voltage VOUT1 obtained in the first time period from the first output voltage VOUT1 obtained in the second time period.
Fig. 9 is a diagram showing the constitution of a user equipment according to an embodiment of the present invention.
The user equipment 100 of one embodiment of the present invention may include: a user input device 2 comprising the sense electrode RX and the drive electrode TX; the touch input detection device 1; and a main processing device 3 for receiving and providing the capacitance correlation value formed at the sensing electrode RX measured by the touch input detecting device 1 from the touch input detecting device 1. The user equipment 100 may further comprise: a display unit 4 controlled by the main processing device 3; a storage unit 5 that stores data required by the main processing device 3; a communication unit 6 that transmits and receives signals to and from an external device of the user equipment 100; and a power supply unit 7 that supplies power to the user equipment 100. The user input device 2 may be a transparent touch panel, and the user input device 2 may be manufactured according to a manufacturing process of the display part or manufactured separately from the display part. The touch input detection device 1 may be provided in a chip (chip) form.
With the embodiments of the present invention described above, various changes and modifications can be easily made by those skilled in the art to which the present invention pertains without departing from the essential characteristics of the present invention. The contents of each claim item of the claims can be combined with other claim items having no reference relationship within the scope that can be understood from the present specification.

Claims (13)

1. A touch input detection device, comprising:
A first operational amplifier (OA 1);
A second operational amplifier (OA 2);
A switching unit (20) for selectively connecting a sense electrode (RX) to only one of the inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier;
A driving unit (10) for connecting a signal having a predetermined pattern to a driving electrode (TX) forming a mutual capacitance with the sensing electrode, and changing the potential of the driving electrode in synchronization with the state change of the switching unit;
a control unit (30) that controls the operation of the switching unit such that a difference Value (VOUT) obtained by subtracting the second output voltage of the second operational amplifier from the first output voltage of the first operational amplifier is gradually reduced in a first time period, and the difference value is gradually increased in a second time period; and
A capacitance measuring section (40) that measures a capacitance-related value formed at the sense electrode based on a first difference value (VOUT 12 1) that is the difference value obtained in the first time interval and a second difference value (VOUT 12 2) that is the difference value obtained in the second time interval,
Wherein the potential of the sensing electrode is caused to change in synchronization with the state change of the switching section.
2. The touch input detection device of claim 1, wherein,
A first reference voltage is applied to a non-inverting input terminal of the first operational amplifier, and a second reference voltage different from the first reference voltage is applied to a non-inverting input terminal of the second operational amplifier.
3. The touch input detection device of claim 1, wherein,
The capacitance measuring unit measures a self capacitance formed by the sense electrode and the circuit element other than the drive electrode based on a value obtained by adding the first difference value and the second difference value.
4. The touch input detection device of claim 1, wherein,
The capacitance measuring section measures the mutual capacitance based on a value obtained by subtracting the first difference value from the second difference value.
5. The touch input detection device of claim 1, wherein,
A capacitor is connected between the inverting input terminal and the output terminal of any one of the first and second operational amplifiers, and if the sensing electrode and the inverting input terminal of the any one of the operational amplifiers are connected to each other according to the operation of the switching section, a voltage across the capacitor is changed by a charge that moves through the sensing electrode.
6. The touch input detection device of claim 1, wherein,
The control unit controls the operation of the switching unit such that the first output voltage is gradually decreased and the second output voltage is gradually increased during the first time period, and the first output voltage is gradually increased and the second output voltage is gradually decreased during the second time period.
7. The touch input detection device of claim 1, wherein,
Further comprises: a first capacitor connected between an inverting input terminal and an output terminal of the first operational amplifier; and
A second capacitor connected between the inverting input terminal and the output terminal of the second operational amplifier;
the control section controls the switching section such that the output value of the first operational amplifier is changed before the output value of the second operational amplifier after resetting the first capacitor and the second capacitor in the first time period, and the output value of the second operational amplifier is changed before the output value of the first operational amplifier after resetting the first capacitor and the second capacitor in the second time period.
8. A touch input detection device, comprising:
A first operational amplifier (OA 1);
A switching unit (20) that connects a sense electrode (RX) to an inverting input terminal of the first operational amplifier;
A driving unit (10) for connecting a signal having a predetermined pattern to a driving electrode (TX) forming a mutual capacitance with the sensing electrode, and changing the potential of the driving electrode in synchronization with the state change of the switching unit;
A control unit (30) that controls the operation of the switching unit such that the first output voltage (VOUT 1) of the first operational amplifier is gradually reduced during a first time period, and the first output voltage (VOUT 1) is gradually increased during a second time period; and
And a capacitance measuring unit (40) that measures the capacitance formed at the sense electrode, based on the first output voltage (VOUT 1) obtained during the first time period and the first output voltage (VOUT 1) obtained during the second time period.
9. The touch input detection device of claim 8, wherein,
So that the potential of the sensing electrode changes in synchronization with the state change of the switching section.
10. The touch input detection device of claim 9, wherein,
The switch part (20) comprises a first switch (phi 1) and a second switch (phi 2),
-Alternately applying a first reference voltage and a second reference voltage to the sense electrode (RX) by means of the first switch (Φ1) and the second switch (Φ2).
11. The touch input detection device of claim 8, wherein,
The capacitance measuring section measures self capacitance formed by the sense electrode and other circuit elements than the drive electrode based on a value obtained by adding the first output voltage (VOUT 1) obtained in the first time period and the first output voltage (VOUT 1) obtained in the second time period.
12. The touch input detection device of claim 8, wherein,
The capacitance measuring section measures the mutual capacitance based on a value obtained by subtracting the first output voltage (VOUT 1) obtained in the first time interval from the first output voltage (VOUT 1) obtained in the second time interval.
13. A user equipment comprising:
the user input device comprises a sensing electrode and a driving electrode;
the touch input detection device of claim 8; and
And main processing means for receiving, from the touch input detecting means, a value related to the capacitance formed at the sense electrode measured by the touch input detecting means.
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