CN117294296A - Capacitance detection method, detection circuit and touch device - Google Patents
Capacitance detection method, detection circuit and touch device Download PDFInfo
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- CN117294296A CN117294296A CN202311225800.9A CN202311225800A CN117294296A CN 117294296 A CN117294296 A CN 117294296A CN 202311225800 A CN202311225800 A CN 202311225800A CN 117294296 A CN117294296 A CN 117294296A
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- 238000001514 detection method Methods 0.000 title claims abstract description 59
- 239000003990 capacitor Substances 0.000 claims abstract description 44
- 238000000034 method Methods 0.000 claims description 6
- 230000000694 effects Effects 0.000 abstract description 3
- 230000010076 replication Effects 0.000 abstract description 2
- 101710170231 Antimicrobial peptide 2 Proteins 0.000 description 14
- 101710170230 Antimicrobial peptide 1 Proteins 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
- 230000006698 induction Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 101000872083 Danio rerio Delta-like protein C Proteins 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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- 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
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- 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
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Abstract
The invention discloses a capacitance detection method, which comprises the steps that under the control of a first clock, a touch capacitor Cs is discharged to the ground, and the charge discharge of a feedback capacitor Cf is cleared; under the control of the second clock, the first amplifier charges the touch capacitor Cs, the charging current copying module copies the charging current in the first amplifier to the second amplifier to charge the feedback capacitor Cf, the output voltage VOUT is obtained, and the change of the touch signal of the touch capacitor Cs is obtained through the change of the output voltage under the first clock and the second clock, wherein the first clock and the second clock are non-overlapping clocks. According to the invention, the charging current replication module with smaller volume is arranged in the capacitance detection circuit to replace the Cb capacitor with larger volume in the detection circuit in the prior art, so that the area of the capacitance detection circuit is reduced under the condition of ensuring the touch detection effect.
Description
Technical Field
The present invention relates to the field of capacitive detection technologies, and in particular, to a capacitive detection method, a capacitive detection circuit, and a touch device.
Background
The capacitive detection technology is widely applied to touch detection chips, is widely applied to touch keys such as induction cookers, door locks, elevators and the like, and is also widely applied to handheld terminals such as mobile phones, tablets and the like.
The existing capacitance detection technology is mainly divided into two main types, namely mutual capacitance detection and self-capacitance detection, wherein the self-capacitance detection technology can emit signals and can detect the signal change of the emitted signals after electric-air modulation. The method comprises the steps of firstly discharging charges on an induction electrode, and then recharging to a certain voltage, wherein the output voltage of the operational amplifier is related to the induction capacitance; the other method is a charging time detection method based on a comparator, which firstly discharges the charge on the induction electrode, then charges the capacitor according to a certain charging rule and calculates the charging time until the corresponding charging time is obtained after the capacitor is charged to a specific voltage, and the charging time is related to the induction capacitor. The capacitance detection method based on the charging time has the advantages of low power consumption, simple implementation and small area, but the detection speed and the anti-interference performance are poorer than those of the method based on the charge transfer, so the self-capacitance detection method for the flat panel equipment such as a mobile phone and the like generally adopts the charge transfer technology.
However, in the current charge transfer technology, an internal capacitor is required to reduce a part of the screen body capacitance, which is also called a substrate capacitance, so that the equivalent detection capacitance is reduced and the detection precision is improved under the condition that the change of the touch capacitance is not changed. The existence of the substrate capacitor can make the area of the detection circuit larger, so that the cost is not reduced.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a capacitance detection method and a capacitance detection circuit capable of reducing the area of a detection circuit, specifically:
a capacitance detection method comprises
The touch control circuit comprises a touch capacitor Cs, a first amplifier and a second amplifier, wherein the touch capacitor Cs is connected with a first input end of the first amplifier, and a second input end of the first amplifier is connected with a reference voltage VREF;
the second amplifier comprises a feedback capacitor Cf, a first input end of the second amplifier is connected with a reference voltage VREF, and an output voltage of the second amplifier is output as an electric signal;
a charging current copying module is arranged between the output end of the first amplifier and the second input end of the second amplifier;
under the first clock control, the touch capacitor Cs is discharged to the ground, and the charge discharge of the feedback capacitor Cf is cleared;
under the control of a second clock, the first amplifier charges the touch capacitor Cs, the charging current copying module copies the charging current in the first amplifier to the second amplifier to charge the feedback capacitor Cf, the output voltage VOUT is obtained, and the change of the touch signal of the touch capacitor Cs is obtained through the change of the output voltage under the first clock and the second clock, wherein the first clock and the second clock are non-overlapping clocks.
In one embodiment, under the second clock, the first amplifier charges the touch capacitor Cs in a unit gain manner, the charging current is Ichg, the charging current copying module copies the charging current Ichg into a copying current, and the copying current is Ichg multiplied by a coefficient a, wherein the coefficient a is adjustable;
the output voltage VOUT is VREF-1/Cf VREF Cs A;
the change DeltaVOUT of the output voltage VOUT and the change of Cs form a DeltaCs linear relation, and the coefficient is A.VREF.1/Cf.
In one embodiment, the feedback capacitor Cf further comprises a charge adjustment module for adjusting a charge Q of the feedback capacitor Cf;
under the adjustment of the charge adjusting module, the output voltage VOUT is
VREF-1/Cf*VREF*Cs*A+Q/Cf。
In one embodiment, the charge Q is Cb VREF, or the charge Q is a desired charge provided in the form of a currentt0 is adjustable.
In one embodiment, the output voltage adjusting module is further configured to inject charge into the input terminal of the second amplifier when the output voltage of the output terminal of the second amplifier exceeds a preset voltage range, so that the output voltage of the output terminal of the second amplifier is kept within the preset voltage range.
In one embodiment, the feedback capacitor Cf of the second amplifier is reset and cleared in the first period, and integrated in a plurality of periods N and then set to the output voltage VOUT
VREF-N1/Cf VREF Cs a+Σm B VREF, where N represents the number of cycles, M represents the number of voltage adjustments, and B VREF represents each voltage adjustment.
A capacitance detection circuit, comprising:
the touch control circuit comprises a touch capacitor Cs, a first amplifier and a second amplifier, wherein the touch capacitor Cs is connected with a first input end of the first amplifier, and a second input end of the first amplifier is connected with a reference voltage VREF;
the second amplifier comprises a feedback capacitor Cf, a first input end of the second amplifier is connected with a reference voltage VREF, and an output voltage of the second amplifier is output as an electric signal;
and a charging current copying module is arranged between the output end of the first amplifier and the second input end of the second amplifier, and is used for copying the charging current of the first amplifier to the second amplifier according to a set coefficient so as to enable the change of the output voltage of the second amplifier to be in linear relation with the change of the touch capacitance.
In one embodiment, the circuit further includes a charge adjustment module, coupled to the second input terminal of the second amplifier, for adjusting the charge Q of the feedback capacitor Cf.
In one embodiment, the circuit further comprises an output voltage adjusting module, wherein one end of the output voltage adjusting module is connected to the second input end of the second amplifier, and the other end of the output voltage adjusting module is connected to the output end of the second amplifier, and is used for injecting charges into the input end of the second amplifier when the output voltage of the output end of the second amplifier exceeds a certain range.
A touch device comprises the capacitance detection circuit.
According to the capacitance detection method, the detection circuit and the touch device, the charging current replication module with smaller volume is arranged in the capacitance detection circuit to replace the Cb capacitance with larger volume in the detection circuit in the prior art, and the area of the capacitance detection circuit is reduced under the condition of ensuring the touch detection effect.
Drawings
FIG. 1 is a schematic diagram of a capacitance detection circuit and a control clock related to the capacitance detection circuit in one embodiment;
FIG. 2 is a schematic diagram of a capacitance detection circuit and a control clock related to the capacitance detection circuit according to another embodiment;
fig. 3 is a schematic structural diagram of a capacitance detection circuit in yet another embodiment and a control clock related to the capacitance detection circuit.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, a capacitance detection circuit is disclosed. The capacitance detection circuit comprises a touch capacitance Cs, a first amplifier AMP1 and a second amplifier AMP2, wherein the touch capacitance Cs is connected to a first input end of the first amplifier AMP1, and a second input end of the first amplifier AMP1 is connected to a reference voltage VREF;
the second amplifier AMP2 includes a feedback capacitor Cf, a first input terminal of the second amplifier AMP2 is connected to the reference voltage VREF, and an output voltage of the second amplifier AMP2 is output as an electrical signal; a charging current copying module is arranged between the output end of the first amplifier AMP1 and the second input end of the second amplifier AMP2, and is used for copying the charging current Ichg of the first amplifier AMP1 to the second amplifier AMP2 with a set coefficient a, and the copied charging current is Ichg multiplied by the coefficient a, wherein the coefficient a is adjustable.
Referring to fig. 1 again, the above-mentioned capacitance detection circuit implements a capacitance detection method under the control of the first clock ph1, the second clock ph2, and the reset clock rst, where the first clock ph1 and the second clock ph2 are non-overlapping clocks, and the reset clock rst and the first clock ph1 overlap by default, but the rising edge and the falling edge can be adjusted.
Under the control of the first clock ph1, the touch capacitance Cs is discharged to the ground while the feedback capacitance Cf of the second amplifier AMP2 is charge-discharged to zero.
Under the control of the second clock ph2, the first amplifier AMP1 charges the touch capacitance Cs, preferably, the touch capacitance Cs is charged in a unit gain manner, and the charging current is Ichg. The charging current copying module copies the charging current in the first amplifier AMP1 to the second amplifier AMP2, the copied charging current is Ichg multiplied by a coefficient a, and the copying current is used for charging the feedback capacitor Cf of the second amplifier AMP2, so that the output voltage VOUT is obtained.
In accordance with the conservation of charge,
thereby obtaining AMP2 output voltage
The change of the output voltage VOUT is linear with the change of Cs, and the coefficient isThe change delta VOUT of the output voltage under the first clock and the second clock is in a linear relation with the change of the touch signal, so that the size of the touch signal can be determined through the delta VOUT, and touch control is further implemented based on the touch signal.
According to the capacitance detection method, the charging current in the first amplifier is copied to the second amplifier through the current copying module to charge the feedback capacitance, so that the change of the output voltage VOUT in the second amplifier and the change of the touch capacitance Cs are in a linear relation, and a touch signal is detected well. The method can replace a Cb capacitor with larger volume in a detection circuit in the prior art, and reduces the area of the capacitance detection circuit under the condition of ensuring the touch detection effect.
In one embodiment, as shown in fig. 2, the apparatus further includes a charge adjustment module for adjusting the charge Q of the feedback capacitor Cf, wherein the output voltage VOUT is
In one embodiment, the charge Q is Cb VREF, or the charge Q is a desired charge provided in the form of a currentThe output charge VOUT may not be easily saturated by the charge regulation module.
In one embodiment, the circuit further comprises an output voltage adjustment module for injecting charge into the input terminal of the second amplifier AMP2 when the output voltage of the output terminal of the second amplifier AMP2 is out of a certain range.
In one embodiment, as shown in fig. 3, under the control of the reset clock rst, the feedback capacitor Cf of the second amplifier AMP2 is reset and cleared only in the first period, and integrated in a plurality of periods N and then becomes the output voltage VOUTWhere N represents the number of cycles, M represents the number of voltage adjustments, and B VRFF represents the voltage adjustment each time.
The output voltage adjusting module can detect the amplitude of the output voltage, after the amplitude exceeds a certain range, certain charges are injected into the input end (the output end connected with the charging current copying module) of the AMP2, so that the output voltage is adjusted by B, VREF is adjusted, and the control coefficient B can enable the output charges VOUT not to be saturated.
In one embodiment, a touch device is disclosed, comprising: the capacitance detection circuit is described above.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. A capacitance detection method is characterized by comprising the following steps of
The touch control circuit comprises a touch capacitor Cs, a first amplifier and a second amplifier, wherein the touch capacitor Cs is connected to a first input end of the first amplifier, and a second input end of the first amplifier is connected to a reference voltage VREF;
the second amplifier comprises a feedback capacitor Cf, a first input end of the second amplifier is connected with a reference voltage VREF, and an output voltage of the second amplifier is output as an electric signal;
a charging current copying module is arranged between the output end of the first amplifier and the second input end of the second amplifier;
under the first clock control, the touch capacitor Cs is discharged to the ground, and the charge discharge of the feedback capacitor Cf is cleared;
under the control of a second clock, the first amplifier charges the touch capacitor Cs, the charging current copying module copies the charging current in the first amplifier to the second amplifier to charge the feedback capacitor Cf, the output voltage VOUT is obtained, and the change of the touch signal of the touch capacitor Cs is obtained through the change of the output voltage under the first clock and the second clock, wherein the first clock and the second clock are non-overlapping clocks.
2. The capacitance detection method according to claim 1, wherein the first amplifier charges the touch capacitance Cs in a unit gain manner at the second clock, a charging current is Ichg, and the charging current copying module copies the charging current Ichg to a copying current, the copying current being Ichg multiplied by a coefficient a, wherein the coefficient a is adjustable;
the output voltage VOUT is
The change of the output voltage VOUT is in linear relation with the change of Cs, and the coefficient is
3. The capacitance detection method according to claim 1, further comprising a charge adjustment module for adjusting a charge Q charged to the feedback capacitance Cf;
under the adjustment of the charge adjusting module, the output voltage VOUT is
4. The method of claim 3, wherein the charge Q is Cb-VREF or the charge Q is a desired charge provided in the form of a currentt0 is adjustable.
5. The capacitance detection method according to claim 1, further comprising an output voltage adjustment module for injecting charge into the input of the second amplifier when the output voltage of the output of the second amplifier exceeds a preset voltage range, so as to keep the output voltage of the output of the second amplifier within the preset voltage range.
6. The method of claim 5, wherein the feedback capacitor Cf of the second amplifier is reset and cleared during a first period, and integrated during a plurality of periods N and then set to the output voltage VOUT
Where N represents the number of cycles, M represents the number of adjustments, and B VREF represents the value of each adjustment.
7. A capacitance detection circuit, comprising:
the touch control circuit comprises a touch capacitor Cs, a first amplifier and a second amplifier, wherein the touch capacitor Cs is connected to a first input end of the first amplifier, and a second input end of the first amplifier is connected to a reference voltage VREF;
the second amplifier comprises a feedback capacitor Cf, a first input end of the second amplifier is connected with a reference voltage VREF, and an output voltage of the second amplifier is output as an electric signal;
and a charging current copying module is arranged between the output end of the first amplifier and the second input end of the second amplifier, and is used for copying the charging current of the first amplifier to the second amplifier according to a set coefficient so as to enable the change of the output voltage of the second amplifier to be in linear relation with the change of the touch capacitance.
8. The capacitance detection circuit according to claim 7, further comprising a charge adjustment module coupled to the second input of the second amplifier for adjusting the charge Q charged to the feedback capacitance Cf.
9. The capacitance sensing circuit of claim 7, further comprising an output voltage adjustment module having one end connected to the second input of the second amplifier and another end connected to the output of the second amplifier for injecting charge into the input of the second amplifier when the output voltage of the output of the second amplifier is out of a certain range.
10. A touch device, comprising:
a capacitance detection circuit according to any one of claims 7 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311225800.9A CN117294296A (en) | 2023-09-22 | 2023-09-22 | Capacitance detection method, detection circuit and touch device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311225800.9A CN117294296A (en) | 2023-09-22 | 2023-09-22 | Capacitance detection method, detection circuit and touch device |
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| Publication Number | Publication Date |
|---|---|
| CN117294296A true CN117294296A (en) | 2023-12-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311225800.9A Pending CN117294296A (en) | 2023-09-22 | 2023-09-22 | Capacitance detection method, detection circuit and touch device |
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| Country | Link |
|---|---|
| CN (1) | CN117294296A (en) |
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- 2023-09-22 CN CN202311225800.9A patent/CN117294296A/en active Pending
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