CN116743148A - Touch key detection circuit - Google Patents
Touch key detection circuit Download PDFInfo
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- CN116743148A CN116743148A CN202310792196.1A CN202310792196A CN116743148A CN 116743148 A CN116743148 A CN 116743148A CN 202310792196 A CN202310792196 A CN 202310792196A CN 116743148 A CN116743148 A CN 116743148A
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- 238000001514 detection method Methods 0.000 title claims abstract description 24
- 239000003990 capacitor Substances 0.000 claims abstract description 64
- 238000007599 discharging Methods 0.000 claims abstract description 22
- 239000003571 electronic cigarette Substances 0.000 claims abstract description 4
- 238000010586 diagram Methods 0.000 description 13
- 230000009977 dual effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Classifications
-
- 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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- Electronic Switches (AREA)
Abstract
The invention provides a touch key detection circuit which is applied to an electronic cigarette and comprises a capacitor unit, a charging and discharging unit, a comparison unit and a control unit, wherein the charging and discharging unit is connected with a plurality of capacitor channels and is used for charging or discharging the capacitor unit, the comparison unit is used for comparing the voltage of the capacitor unit with a threshold voltage so as to output a comparison result signal, the control unit is communicated with the comparison unit and the charging and discharging unit and is used for controlling the charging and discharging unit according to the comparison result signal output by the comparison unit and outputting the result signal, and the charging time of the capacitor unit can be reversely deduced through the output result signal of the comparison unit so as to judge whether a key is pressed down or not, so that the probability of damaging the key is reduced.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to a touch key detection circuit.
Background
Traditional mechanical keys are composed of mechanical parts, are easy to wear and age in the use process, and are physically damaged, and the mechanical keys are required to be perforated on the shell, so that the tightness and the integrity of the product are influenced.
Therefore, it is necessary to provide a novel touch key detection circuit to solve the above-mentioned problems in the prior art.
Disclosure of Invention
The invention aims to provide a touch key detection circuit which reduces the probability of key damage. In order to achieve the above purpose, the touch key detection circuit of the invention is applied to electronic cigarettes and comprises a capacitor unit;
the charging and discharging unit is connected with the capacitance unit and used for charging or discharging the capacitance unit;
a comparison unit for comparing the voltage of the capacitance unit with a threshold voltage to output a comparison result signal; and
and the control unit is communicated with the comparison unit and the charge-discharge unit and is used for controlling the charge-discharge unit according to the comparison result signal output by the comparison unit and outputting a result signal.
The touch key detection circuit has the beneficial effects that: the charging and discharging unit is connected with the capacitance unit and is used for charging or discharging the capacitance unit, the comparison unit is used for comparing the voltage of the capacitance unit with the threshold voltage so as to output a comparison result signal, the control unit is communicated with the comparison unit and the charging and discharging unit and is used for controlling the charging and discharging unit according to the comparison result signal output by the comparison unit and outputting the result signal, and the charging time of the capacitance unit can be reversely deduced through the output result signal of the comparison unit, so that whether a key is pressed down or not is judged, a mechanical key is replaced, and the probability of key damage is reduced.
Optionally, the capacitor unit includes a plurality of capacitor channels, the capacitor channels include a capacitor and a capacitor switch, one end of the capacitor is connected with one end of the capacitor switch, and the other end of the capacitor is connected with a fixed level or grounded.
Optionally, the charge-discharge unit includes first current source, first switch, second switch and first resistance, the negative pole of first current source connects power supply voltage, the positive pole of first current source with the one end of first switch is connected, the other end of first switch with capacitive unit with the one end of first resistance is connected, the other end of first resistance with the one end of second switch is connected, the other end ground connection of second switch.
Optionally, the threshold voltage includes a first sub-threshold voltage, the comparing unit includes a first comparator, a positive phase input end of the first comparator is connected to the first sub-threshold voltage, a negative phase input end of the first comparator is connected to the capacitor unit, and an output end of the first comparator is connected to the control unit.
Optionally, the control unit is configured to control the first switch to be turned on, control the second switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input end of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, and the output of the control unit follows the output of the first comparator to be turned over, and then control the first switch to be turned off, and control the second switch to be turned on, so as to discharge the capacitor unit.
Optionally, the charge-discharge unit includes first current source, first switch, second switch, first resistance, third switch, second current source and fourth switch, the negative pole of first current source connects power supply voltage, the positive pole of first current source with the one end of first switch is connected, the other end of first switch with capacitive unit with the first end of fourth switch is connected, the second end of fourth switch with the one end of first resistance is connected, the other end of first resistance with the one end of second switch is connected, the other end of second switch is grounded, the third end of fourth switch with the negative pole of second current source is connected, the positive pole of second current source with the one end of third switch is connected, the other end of third switch is grounded.
Optionally, the threshold voltage includes a first sub-threshold voltage and a second sub-threshold voltage, the comparing unit includes a first comparator and a second comparator, a positive phase input end of the first comparator is connected with the first sub-threshold voltage, a negative phase input end of the first comparator is connected with the capacitor unit, an output end of the first comparator is connected with the control unit, an inverting input end of the second comparator is connected with the second sub-threshold voltage, a positive phase input end of the second comparator is connected with the capacitor unit, and an output end of the second comparator is connected with the control unit.
Optionally, the control unit is configured to control the first switch to be turned on, control the first control end and the second control end of the fourth switch to be turned on, control the second switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input end of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, the output of the control unit is turned over along with the output of the first comparator, and then control the first switch to be turned off, and control the second switch to be turned on, so as to discharge the capacitor unit.
Optionally, the control unit is configured to control the first switch to be turned on, control the first control end and the third control end of the fourth switch to be turned on, control the third switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input end of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, the output of the control unit is turned over along with the output of the first comparator, then control the first switch to be turned off, control the third switch to be turned on, so as to discharge the capacitor unit, and when the voltage of the positive phase input end of the second comparator reaches the second sub-threshold voltage, the output of the second comparator is turned over, and the output of the control unit is turned over along with the output of the second comparator.
Drawings
FIG. 1 is a schematic diagram of a touch key detection circuit according to the present invention;
FIG. 2 is a circuit conduction diagram of a single threshold mode of the touch key detection circuit shown in FIG. 1;
FIG. 3 is a timing diagram of the turn-on diagram of the circuit shown in FIG. 2;
FIG. 4 is a circuit conduction diagram of a dual threshold mode of the touch key detection circuit of FIG. 1;
fig. 5 is a timing diagram of the circuit turn-on diagram shown in fig. 2.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. Unless otherwise defined, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the word "comprising" and the like means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof without precluding other elements or items.
Aiming at the problems existing in the prior art, the embodiment of the invention provides a touch key detection circuit which is applied to electronic cigarettes. Referring to fig. 1, the touch key detection circuit includes a capacitance unit 101, a charge and discharge unit 102, a comparison unit 103, and a control unit 104.
The charging and discharging unit is connected with the capacitance unit and used for charging or discharging the capacitance unit; the comparison unit is used for comparing the voltage of the capacitor unit with a threshold voltage so as to output a comparison result signal; the control unit is communicated with the comparison unit and the charging and discharging unit and is used for controlling the charging and discharging unit according to the comparison result signal output by the comparison unit and outputting a result signal.
Referring to fig. 1, the capacitor unit includes 101 several capacitor channels, for example, eight capacitor channels CH0 to CH7, where the capacitor channels include a capacitor and a capacitor switch CS, one end of the capacitor is connected to one end of the capacitor switch, and the other end of the capacitor is connected to a fixed level or to ground.
In some embodiments, the charge-discharge unit includes a first current source, a first switch, a second switch and a first resistor, a negative electrode of the first current source is connected to a power supply voltage, a positive electrode of the first current source is connected to one end of the first switch, the other end of the first switch is connected to the capacitor unit and one end of the first resistor, the other end of the first resistor is connected to one end of the second switch, and the other end of the second switch is grounded. Only one current source is provided, so that the power consumption can be greatly reduced.
In some embodiments, the threshold voltage includes a first sub-threshold voltage, the comparing unit includes a first comparator, a positive phase input end of the first comparator is connected to the first sub-threshold voltage, a negative phase input end of the first comparator is connected to the capacitor unit, and an output end of the first comparator is connected to the control unit.
In some embodiments, the control unit is configured to control the first switch to be turned on, control the second switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input end of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, and the output of the control unit follows the output of the first comparator to be turned over, and then control the first switch to be turned off, and control the second switch to be turned on, so as to discharge the capacitor unit.
Referring to fig. 1, the charge-discharge unit 102 includes a first current source I1, a first switch S1, a second switch S2, a first resistor R1, a third switch S3, a second current source I2, and a fourth switch S4, wherein a negative electrode of the first current source I1 is connected to a power supply voltage, a positive electrode of the first current source I1 is connected to one end of the first switch S1, the other end of the first switch S1 is connected to the capacitor unit 101 and a first end of the fourth switch S4, a second end of the fourth switch S4 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to one end of the second switch S2, the other end of the second switch S2 is grounded, a third end of the fourth switch S4 is connected to a negative electrode of the second current source I2, a positive electrode of the second current source I2 is connected to one end of the third switch S3, and the other end of the third switch S3 is grounded.
Referring to fig. 1, the threshold voltage includes a first sub-threshold voltage h_vth and a second sub-threshold voltage l_vth, the comparing unit 103 includes a first comparator U1 and a second comparator U2, a non-inverting input terminal of the first comparator U1 is connected to the first sub-threshold voltage h_vth, a non-inverting input terminal of the first comparator U1 is connected to the capacitor unit 101, an output terminal of the first comparator U1 is connected to the control unit 104, an inverting input terminal of the second comparator U2 is connected to the second sub-threshold voltage l_vth, a non-inverting input terminal of the second comparator U2 is connected to the capacitor unit 101, and an output terminal of the second comparator U2 is connected to the control unit 104.
Optionally, the control unit is configured to control the first switch to be turned on, control the first control end and the second control end of the fourth switch to be turned on, control the second switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input end of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, the output of the control unit is turned over along with the output of the first comparator, and then control the first switch to be turned off, and control the second switch to be turned on, so as to discharge the capacitor unit.
Fig. 2 is a circuit conduction diagram of a single threshold mode of the touch key detection circuit shown in fig. 1. FIG. 3 is a timing diagram of the turn-on diagram of the circuit shown in FIG. 2. Referring to fig. 1, fig. 2 and fig. 3, the second comparator U2 is disabled, the control unit 104 controls the first switch S1 to be turned on, controls the first control terminal and the second control terminal of the fourth switch S4 to be turned on, controls the second switch S2 to be turned off, the first current source I1 charges the capacitor unit 101, the voltage of the inverting input terminal of the first comparator U1 increases linearly, when the voltage of the inverting input terminal of the first comparator U1 reaches the first sub-threshold voltage h_vth, the output of the first comparator U1 is turned over, and the result signal osc_out output by the control unit 104 follows the output of the first comparator U1 to be turned over; the control unit 104 controls the first switch S1 to be turned off, and controls the second switch S2 to be turned on, so as to discharge the capacitor unit 101.
Referring to FIG. 2, due toThe resistance value of the first resistor R1 is small, and the discharging speed of the capacitor unit 101 is fast, so that the discharging time can be ignored, and the capacitance value can be calculated through the first capacitance calculation formula. The first capacitance calculation formula may be expressed asI represents a current value of the first current source I1, C represents a capacitance value of the capacitance unit 101, T represents a period of an output signal of the control unit 104, and h_vth represents the first sub-threshold voltage h_vth.
Optionally, the control unit is configured to control the first switch to be turned on, control the first control end and the third control end of the fourth switch to be turned on, control the third switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input end of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, the output of the control unit is turned over along with the output of the first comparator, then control the first switch to be turned off, control the third switch to be turned on, so as to discharge the capacitor unit, and when the voltage of the positive phase input end of the second comparator reaches the second sub-threshold voltage, the output of the second comparator is turned over, and the output of the control unit is turned over along with the output of the second comparator.
Fig. 4 is a circuit conduction diagram of a dual threshold mode of the touch key detection circuit shown in fig. 1. FIG. 5 is a timing diagram of the turn-on diagram of the circuit shown in FIG. 4. Referring to fig. 1, fig. 4 and fig. 5, the control unit 104 controls the first switch S1 to be turned on, controls the first control terminal and the third control terminal of the fourth switch S4 to be turned on, controls the third switch S3 to be turned off, the first current source I1 charges the capacitor unit 101, the voltages of the inverting input terminal of the first comparator U1 and the non-inverting input terminal of the second comparator U2 linearly rise, when the voltage of the negative-phase input terminal of the first comparator U1 reaches the first sub-threshold voltage h_vth, the output of the first comparator U1 turns over, the result signal osc_out output by the control unit 104 follows the output of the first comparator U1, then controls the first switch S1 to be turned off, controls the third switch S3 to be turned on, the second current source I2 linearly rises the voltage of the capacitor unit 101, when the voltage of the inverting input terminal of the first comparator U1 and the positive-phase input terminal of the second comparator U2 reaches the first sub-threshold voltage h_vth, and the result signal osc_out output by the control unit 104 turns over when the voltage of the positive-phase comparator U2 reaches the second sub-threshold voltage L2.
Referring to fig. 4, the capacitance value can be calculated by the second capacitance calculation formula. The second capacitance calculation formula may be expressed asI1 represents a current value of the first current source, I2 represents a current value of the second current source, C represents a capacitance value of the capacitance unit, T represents a period of an output signal of the control unit, h_vth represents the first sub-threshold voltage, and l_vth represents the second sub-threshold voltage. In some preferred embodiments, I1 is equal to I2.
Referring to fig. 2 and 4, in the single threshold mode, the pull-down time is configurable, and an appropriate pull-down time may be selected to ensure that the pull-down of the capacitor unit 101 is to 0V. The currents of the first current source I1 and the second current source I2 of the single-threshold mode and the double-threshold mode are each configurable so as to select an appropriate current in the case of different capacitances. The number of counts of the output signals of the control unit 104 can be configured, and the reliability of the test result can be ensured by counting for a long time. Only one current source works in the single-threshold mode, so that the power consumption can be reduced, the discharging speed can be controlled in the double-threshold mode, when the effective capacitance of the capacitance unit 101 is larger, the currents of the first current source I1 and the second current source I2 can be set larger, the charging and discharging time is reduced, when the effective capacitance of the capacitance unit 101 is smaller, the currents of the first current source I1 and the second current source I2 can be set smaller, the charging and discharging speed is prevented from being too fast, and the measuring accuracy is ensured. A single threshold mode and a double threshold mode are realized, and when the effective capacitance of the capacitance unit 101 is small, the single threshold mode can be used to save power consumption, and when the effective capacitance of the capacitance unit 101 is large, the double threshold mode can be used to satisfy measurement accuracy. In order to measure the capacitance of the capacitance unit 101, it is generally necessary to measure the charging time of the capacitance, the invention can trigger the comparator to flip and output the high-low level pulse through each charge and discharge, and calculate the time of the high-low level pulse to flip for a plurality of times to reversely push the charging time of the capacitance. When the charging time of the capacitor unit 101 is very fast, the number of times of high-low level pulse inversion can be increased to obtain higher precision, and when the charging time of the capacitor unit 101 is very slow, the number of times of high-low level pulse inversion can be reduced to obtain faster response speed.
While embodiments of the present invention have been described in detail hereinabove, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. It is to be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the following claims. Moreover, the invention described herein is capable of other embodiments and of being practiced or of being carried out in various ways.
Claims (9)
1. A touch key detection circuit is applied to electronic cigarettes and is characterized by comprising
A capacitor unit;
the charging and discharging unit is connected with the capacitance unit and used for charging or discharging the capacitance unit;
a comparison unit for comparing the voltage of the capacitance unit with a threshold voltage to output a comparison result signal; and
and the control unit is communicated with the comparison unit and the charge-discharge unit and is used for controlling the charge-discharge unit according to the comparison result signal output by the comparison unit and outputting a result signal.
2. The touch key detection circuit of claim 1, wherein the capacitive unit comprises a plurality of capacitive channels, the capacitive channels comprise a capacitor and a capacitive switch, one end of the capacitor is connected with one end of the capacitive switch, and the other end of the capacitor is connected with a fixed level or grounded.
3. The touch key detection circuit according to claim 1, wherein the charge-discharge unit includes a first current source, a first switch, a second switch, and a first resistor, a negative electrode of the first current source is connected to a power supply voltage, a positive electrode of the first current source is connected to one end of the first switch, the other end of the first switch is connected to the capacitor unit and one end of the first resistor, the other end of the first resistor is connected to one end of the second switch, and the other end of the second switch is grounded.
4. The touch key detection circuit of claim 3, wherein the threshold voltage comprises a first sub-threshold voltage, the comparison unit comprises a first comparator, a non-inverting input of the first comparator is connected with the first sub-threshold voltage, a non-inverting input of the first comparator is connected with the capacitance unit, and an output of the first comparator is connected with the control unit.
5. The touch key detection circuit according to claim 4, wherein the control unit is configured to control the first switch to be turned on, control the second switch to be turned off, so as to charge the capacitor unit, and when the voltage at the negative input end of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is inverted, the output of the control unit is inverted along with the output of the first comparator, and then control the first switch to be turned off, and control the second switch to be turned on, so as to discharge the capacitor unit.
6. The touch key detection circuit according to claim 1, wherein the charge-discharge unit includes a first current source, a first switch, a second switch, a first resistor, a third switch, a second current source, and a fourth switch, a negative electrode of the first current source is connected to a power supply voltage, a positive electrode of the first current source is connected to one end of the first switch, the other end of the first switch is connected to the capacitor unit and the first end of the fourth switch, a second end of the fourth switch is connected to one end of the first resistor, the other end of the first resistor is connected to one end of the second switch, the other end of the second switch is grounded, a third end of the fourth switch is connected to a negative electrode of the second current source, a positive electrode of the second current source is connected to one end of the third switch, and the other end of the third switch is grounded.
7. The touch key detection circuit of claim 6, wherein the threshold voltage comprises a first sub-threshold voltage and a second sub-threshold voltage, the comparison unit comprises a first comparator and a second comparator, a positive phase input of the first comparator is connected with the first sub-threshold voltage, a negative phase input of the first comparator is connected with the capacitance unit, an output of the first comparator is connected with the control unit, an inverting input of the second comparator is connected with the second sub-threshold voltage, a positive phase input of the second comparator is connected with the capacitance unit, and an output of the second comparator is connected with the control unit.
8. The touch key detection circuit according to claim 7, wherein the control unit is configured to control the first switch to be turned on, control the first control terminal and the second control terminal of the fourth switch to be turned on, control the second switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input terminal of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, and the output of the control unit follows the output of the first comparator, and then control the first switch to be turned off, and control the second switch to be turned on, so as to discharge the capacitor unit.
9. The touch key detection circuit according to claim 7, wherein the control unit is configured to control the first switch to be turned on, control the first control terminal and the third control terminal of the fourth switch to be turned on, control the third switch to be turned off, so as to charge the capacitor unit, and when the voltage of the negative phase input terminal of the first comparator reaches the first sub-threshold voltage, the output of the first comparator is turned over, and then control the first switch to be turned off, control the third switch to be turned on, so as to discharge the capacitor unit, and when the voltage of the positive phase input terminal of the second comparator reaches the second sub-threshold voltage, the output of the second comparator is turned over, and the output of the control unit is turned over, and then the output of the second comparator is turned over.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310792196.1A CN116743148A (en) | 2023-06-29 | 2023-06-29 | Touch key detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310792196.1A CN116743148A (en) | 2023-06-29 | 2023-06-29 | Touch key detection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116743148A true CN116743148A (en) | 2023-09-12 |
Family
ID=87905917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310792196.1A Pending CN116743148A (en) | 2023-06-29 | 2023-06-29 | Touch key detection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116743148A (en) |
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2023
- 2023-06-29 CN CN202310792196.1A patent/CN116743148A/en active Pending
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