CN202889321U - Capacitive touch key circuit - Google Patents
Capacitive touch key circuit Download PDFInfo
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- CN202889321U CN202889321U CN 201220543631 CN201220543631U CN202889321U CN 202889321 U CN202889321 U CN 202889321U CN 201220543631 CN201220543631 CN 201220543631 CN 201220543631 U CN201220543631 U CN 201220543631U CN 202889321 U CN202889321 U CN 202889321U
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Abstract
The utility model discloses a capacitive touch key circuit, wherein a capacitive touch key connected to the circuit is a sensing metal piece connected with the printed board of the circuit; when the sensing metal piece is touched by the human body, the sensing metal piece and the ground wire form upper and lower polar plates of a sensing capacitor; and the sensing metal piece serves as the sensing capacitor in the capacitive touch key circuit. The capacitive touch key circuit comprises a digital phase-locked loop and a reference oscillating circuit, wherein the digital phase-locked loop is composed of a phase discriminator, a digital accumulator and a controllable oscillating circuit which are in ordered closed-loop connection with each other; the phase discriminator compares the output of the controllable oscillating circuit with the output of the reference oscillating circuit to obtain the phase difference thereof; the digital accumulator accumulates the phase difference and outputs a controlled quantity to the controllable oscillating circuit; the controllable oscillating circuit is under control of the controlled quantity; and the capacitive touch key is connected with the controllable oscillating circuit of the digital phase-locked loop.
Description
Technical field
The utility model relates to the electronic circuit technology field, relates in particular to a kind of capacitance type touch key circuit.
Background technology
Capacitance type touch key is a kind of button implementation of novelty.Contrast traditional mechanical key, capacitance type touch key has simple for structure, and appearance design is beautiful, and push button longevity is long, highly sensitive, controls and experiences the advantages such as good.Increasing household appliances manufacturer begins capacitance type touch key is applied in the middle of the product design.
The key that capacitance type touch key is realized is the detection method to the capacitance variation of inductance capacitance.Existing capacitance detection mode, as adopt a built-in constant-current source to discharging and recharging that outside electrode capacitance constantly circulates, thus and circuit utilizes timing function to discharge and recharge number of times in the unit interval determines whether effective key-press event.
The problem of the method is, precision is difficult accomplishes very high and easily be subject to the interference of external complex electromagnetic environment.Thereby the present reliability that improves button in the urgent need to a kind of new capacitance type touch key detection mode.
The utility model content
For in the prior art to the shortcoming of the capacitance detecting mode of capacitance type touch key, the utility model proposes a kind of capacitance touch button circuit of novelty.
The technical solution of the utility model is, a kind of capacitance type touch key circuit, wherein, the capacitance type touch key that accesses this circuit is an induction metal plate that is connected with the printed board of this circuit, when this induction metal plate of human body touch, this induction metal plate and ground wire form the upper bottom crown of inductance capacitance, described induction metal plate plays the effect of inductance capacitance in described capacitance type touch key circuit, described capacitance type touch key circuit comprises a digital phase-locked loop and a reference oscillation circuit
Described digital phase-locked loop forms the order closed loop by phase discriminator, digital accumulator and controllable oscillatory circuit and connects to form, the phase difference of the output of the more described controllable oscillatory circuit of described phase discriminator and the output of reference oscillation circuit, described digital accumulator is accumulated described phase difference and output to the controlled quentity controlled variable of described controllable oscillatory circuit, described controllable oscillatory circuit is subject to the regulation and control of described controlled quentity controlled variable
Described capacitance type touch key is connected with the controllable oscillatory circuit of described digital phase-locked loop.
Further, the standard RC oscillating circuit that described reference oscillation circuit is comprised of reference capacitance resistance produces a stable benchmark frequency of oscillation.
Further, the controlled RC oscillator that described controllable oscillatory circuit is comprised of the induction metal plate that plays the inductance capacitance effect, adjustable resistance chain, comparator and gate, described adjustable resistance chain are subjected to the controlled quentity controlled variable of described digital accumulator output to control to change the access resistance value.
Further, the controlled oscillator that described controllable oscillatory circuit is comprised of the induction metal plate that plays the inductance capacitance effect, adjustable current source, comparator and gate, described adjustable current source are subjected to the controlled quentity controlled variable of described digital accumulator output to control to change the charging and discharging currents value.
The designed capacitance type touch key circuit of the utility model is a digital phase-locking phase ring structure to the detection main body of the inductance capacitance of touch key-press, the RC circuit that is comprised of inductance capacitance and adjustable resistance chain (perhaps adjustable current source) is its controllable oscillatory structure, and other structures of phase-locked loop comprise phase discriminator and digital accumulator.Phase discriminator differentiates that the frequency plot of input reference signal and controllable oscillatory structure output signal is poor, and digital accumulator is then accumulated the phase difference next by phase discriminator, thereby generates the digital controlled signal of the adjustable oscillating structure of control.
The utility model is by Digital Phase-Locked Loop Technology, and locking is to the time that discharges and recharges of electric capacity, and the size of the charging and discharging currents of the inductance capacitance that phase-locked loop is controlled automatically just can reflect the capacitance variation of inductance capacitance.
Description of drawings
Fig. 1 is the electric circuit constitute principle schematic of the utility model one embodiment.
Embodiment
As shown in Figure 1, the specific works mode of circuit structure is that two inputs of phase discriminator are respectively the output signal of controllable oscillatory structure and the benchmark oscillator signal that is produced by the chip internal reference oscillation circuit.Two signals of phase discriminator comparison also produce their phase difference.By the accumulation of digital accumulator, the control signal of controllable oscillatory structure produces according to the phase difference of two signals and changes, thereby the output signal of controllable oscillatory structure changes to the direction near reference oscillation circuit more.When digital phase-locked loop locked, the output signal of controllable oscillatory structure was consistent with the output of reference oscillation circuit, and phase discriminator is output as 0, and the control signal of digital accumulator output no longer changes, and it is stable that system reaches.
When the inductance capacitance in the controllable oscillatory structure in the circuit since human body when capacitance occuring changing near, the output of controllable oscillatory structure will be no longer be consistent with the output of reference oscillation circuit.And digital phase-locked loop will be this inconsistent control end that feeds back to the controllable oscillatory structure.Control signal will change the resistance (or discharging and recharging flow valuve) of adjustable resistance chain (perhaps adjustable current source), and it is large that the inductance capacitance value becomes, and then discharges and recharges rheology large, and the inductance capacitance value diminishes, and then charging or discharging current is corresponding diminishes.Circuit structure is adjusted to the output of controllable oscillatory structure consistent with reference oscillation circuit fast.And discharge and recharge this moment in the identical situation of time, the size of charging or discharging current namely can be reacted the size of inductance capacitance value.The control signal that only needs to detect the controllable oscillatory structure changes, and just can realize the detection to capacitance type touch key.
To sum up, a kind of capacitance type touch key testing circuit of the present utility model, this new circuit has been used the digital PLL circuit technology, comprises the circuit structure of a digital phase-locked loop and a reference oscillation circuit.Described digital phase-locked loop is by phase discriminator, and digital accumulator and controllable oscillatory structure form.The phase difference of the output of the more described controllable oscillatory structure of described phase discriminator and the output of reference oscillation circuit; Described digital accumulator is accumulated described phase difference and output to the controlled quentity controlled variable of described controllable oscillatory structure; And the controlled quentity controlled variable that described controllable oscillatory structure is accepted prime is regulated and control.
The standard RC oscillating circuit that described reference oscillation circuit is comprised of the reference capacitance resistance of chip internal will produce a stable benchmark frequency of oscillation.
Described controllable oscillatory structure is by inductance capacitance, the controlled RC oscillator that adjustable resistance chain and comparator and gate form.Described adjustable resistance chain is subjected to the controlled quentity controlled variable of prime to control to change the access resistance value; Described inductance capacitance will be responded to human body and touch and change electric capacity.
Described inductance capacitance comes from the induction metal plate on the outer printed circuit board (PCB) of chip, and with the upper bottom crown of ground wire formation inductance capacitance, the human body approach induction metal plate will increase the capacitance of inductance capacitance.
It is consistent with the output of described reference oscillation circuit that described digital phase-locked loop is controlled the output of described controllable oscillatory structure.The RC of controllable oscillatory structure discharged and recharged the time and discharged and recharged time consistency in reference oscillation circuit RC this moment.The charging and discharging currents that determines of adjustable resistance chain of controllable oscillatory structure was followed described inductance capacitance appearance value and was changed this moment, the controlled quentity controlled variable of adjustable resistance chain namely reflects the size of inductance capacitance value, variation by measuring this controlled quentity controlled variable is the inductance capacitance value of induction metal plate as can be known, thereby can realize the detection of capacitance type touch key.
A kind of capacitance type touch key circuit implementation of the present utility model, utilization Digital Phase-Locked Loop Technology are realized the frequency of the RC oscillating circuit that is comprised of inductance capacitance and adjustable resistance chain is locked.Along with the variation of inductance capacitance, change the charging or discharging current of inductance capacitance by the resistance value that changes the adjustable resistance chain, by detecting the change of charging or discharging current, can obtain the variation of inductance capacitance value, thereby realize the measuring ability of capacitance type touch key.
Claims (4)
1. capacitance type touch key circuit, wherein, the capacitance type touch key that accesses this circuit is an induction metal plate that links to each other with the printed board of this circuit, when this induction metal plate of human body touch, this induction metal plate and ground wire form the upper bottom crown of inductance capacitance, and described induction metal plate plays the effect of inductance capacitance in described capacitance type touch key circuit, it is characterized in that, described capacitance type touch key circuit comprises a digital phase-locked loop and a reference oscillation circuit
Described digital phase-locked loop is by phase discriminator, digital accumulator and controllable oscillatory circuit formation order closed loop connect to form, the phase difference of the output of the more described controllable oscillatory circuit of described phase discriminator and the output of reference oscillation circuit, described digital accumulator is accumulated described phase difference and output to the controlled quentity controlled variable of described controllable oscillatory circuit, described controllable oscillatory circuit is subject to the regulation and control of described controlled quentity controlled variable, described controlled quentity controlled variable is with the capacitance variation of described touch key-press, detecting described controlled quentity controlled variable changes, to realize the measuring ability of capacitance type touch key, described capacitance type touch key consists of the part of the controllable oscillatory circuit of described digital phase-locked loop.
2. capacitance type touch key circuit as claimed in claim 1 is characterized in that, the standard RC oscillating circuit that described reference oscillation circuit is comprised of reference capacitance resistance produces a stable benchmark frequency of oscillation.
3. capacitance type touch key circuit as claimed in claim 1, it is characterized in that, the controlled RC oscillator that described controllable oscillatory circuit is comprised of the induction metal plate that plays the inductance capacitance effect, adjustable resistance chain, comparator and gate, described adjustable resistance chain are subjected to the controlled quentity controlled variable of described digital accumulator output to control to change the access resistance value.
4. capacitance type touch key circuit as claimed in claim 1, it is characterized in that, the controlled oscillator that described controllable oscillatory circuit is comprised of the induction metal plate that plays the inductance capacitance effect, adjustable current source, comparator and gate, described adjustable current source are subjected to the controlled quentity controlled variable of described digital accumulator output to control to change the charging and discharging currents value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220543631 CN202889321U (en) | 2012-10-22 | 2012-10-22 | Capacitive touch key circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220543631 CN202889321U (en) | 2012-10-22 | 2012-10-22 | Capacitive touch key circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202889321U true CN202889321U (en) | 2013-04-17 |
Family
ID=48080707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220543631 Expired - Lifetime CN202889321U (en) | 2012-10-22 | 2012-10-22 | Capacitive touch key circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202889321U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103259517A (en) * | 2013-05-20 | 2013-08-21 | 百利通电子(上海)有限公司 | Capacitor type touch circuit and capacitor detection method thereof |
| WO2018227492A1 (en) * | 2017-06-15 | 2018-12-20 | 深圳市汇顶科技股份有限公司 | Button device for use in electronic equipment and electronic equipment |
| CN116455380A (en) * | 2023-04-23 | 2023-07-18 | 无锡中微爱芯电子有限公司 | High-sensitivity touch CCT circuit with built-in capacitor and self-adaptive environment |
-
2012
- 2012-10-22 CN CN 201220543631 patent/CN202889321U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103259517A (en) * | 2013-05-20 | 2013-08-21 | 百利通电子(上海)有限公司 | Capacitor type touch circuit and capacitor detection method thereof |
| WO2018227492A1 (en) * | 2017-06-15 | 2018-12-20 | 深圳市汇顶科技股份有限公司 | Button device for use in electronic equipment and electronic equipment |
| CN116455380A (en) * | 2023-04-23 | 2023-07-18 | 无锡中微爱芯电子有限公司 | High-sensitivity touch CCT circuit with built-in capacitor and self-adaptive environment |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20130417 |
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| CX01 | Expiry of patent term |