CN205566268U - Keying circuit and tame electric installation - Google Patents

Abstract

The utility model provides a keying circuit and tame electric installation, keying circuit includes square signal generating circuit, electric capacity induced key, electric capacity voltage sampling circuit and charging and discharging circuit, charging and discharging circuit receives the square wave that square signal generating circuit produced is right the electric capacity induced key carries out the charge -discharge, electric capacity voltage sampling circuit detects the voltage fluctuation of electric capacity induced key is in order to judge whether the electric capacity induced key is touched. Produce square signal through square signal generating circuit to introduce electric capacity voltage sampling circuit's sense terminal to the electric capacity voltage signal in the electric capacity induced key, calculate the voltage signal's at electric capacity induced key both ends big microvariation through electric capacity voltage sampling circuit, thereby can realize the discernment of electric capacity induced key, have with low costs, easy realization, advantages such as reliability height.

Description

A kind of key circuit and home appliance

Technical field

This utility model relates to electronic switching technology, particularly relates to a kind of key circuit and home appliance.

Background technology

At present in equipment, generally button mechanically, this mode is made to use sense organ poor with key circuit, And owing to being the contact of frame for movement, life-time service easily produces physical deterioration so that service life is significantly It is affected.

Utility model content

This utility model purpose is to provide a kind of contactless key circuit, it is intended to solve traditional machinery Case uses easily loss, the problem that the life-span is low.

This utility model provides a kind of key circuit, including square-wave signal generation circuit, cap-sensor, Capacitance voltage sample circuit and charge-discharge circuit, described charge-discharge circuit is passed through in described cap-sensor one end It is connected with the outfan of described square-wave signal generation circuit, described cap-sensor other end ground connection, and institute State the cap-sensor other end test side by described charge-discharge circuit with described capacitance voltage sample circuit Connect；Described charge-discharge circuit receives the square wave of described square-wave signal generation circuit generation to described capacitive sensing Button carries out discharge and recharge, described capacitance voltage sample circuit detect the voltage pulsation of described cap-sensor with Judge whether described cap-sensor is touched.

Preferably, described square-wave signal generation circuit is made up of microprocessor, described square-wave signal generation circuit The PWM output port that outfan is described microprocessor.

Preferably, described capacitance voltage sample circuit is made up of described microprocessor, and described capacitance voltage is sampled The test side of circuit is the A/D sample port of described microprocessor.

Preferably, described microprocessor is single-chip microcomputer.

Preferably, described charge-discharge circuit include the first diode, the second diode, the first resistance, second Resistance and the first electric capacity, wherein:

One end of described first resistance and the negative electrode of described first diode, described square-wave signal generation circuit Outfan is connected, the other end of described first resistance and the anode of described first diode, above-mentioned two or two pole The anode of pipe, one end of described cap-sensor are connected, the other end ground connection of described cap-sensor, The negative electrode of described second diode connects the test side of described capacitance voltage sample circuit, and by described second electricity Resistance ground connection, described first electric capacity and described second resistor coupled in parallel.

This utility model additionally provides a kind of home appliance, including above-mentioned key circuit.

Above-mentioned key circuit produces square-wave signal by square-wave signal generation circuit, and capacitive sensing is pressed Capacitance voltage signal in key introduces the test side of capacitance voltage sample circuit, by capacitance voltage sample circuit Calculate the size variation of the voltage signal at cap-sensor two ends, thus the knowledge of cap-sensor can be realized Not, there is low cost, be easily achieved, high reliability.

Accompanying drawing explanation

Fig. 1 is the circuit diagram of key circuit in this utility model preferred embodiment；

Fig. 2 is the operation principle oscillogram of key circuit shown in Fig. 1.

Detailed description of the invention

In order to make the technical problems to be solved in the utility model, technical scheme and beneficial effect clearer, Below in conjunction with drawings and Examples, this utility model is further elaborated.Should be appreciated that herein Described specific embodiment, only in order to explain this utility model, is not used to limit this utility model.

Refer to Fig. 1, this utility model preferred embodiment is arranged at the contactless button of home appliance Circuit, it include square-wave signal generation circuit 10, capacitance voltage sample circuit 20, charge-discharge circuit 30 and Cap-sensor 40, there is electricity by charge-discharge circuit 30 with square-wave signal in cap-sensor 40 one end The outfan on road 10 connects, cap-sensor 40 other end ground connection, and by charge-discharge circuit 30 and electricity The test side holding voltage sampling circuit 20 connects；Charge-discharge circuit 30 receives square-wave signal generation circuit 10 The square wave produced carries out discharge and recharge to cap-sensor 40, and capacitance voltage sample circuit 20 detects electric capacity sense Answer the voltage pulsation of button 40 to judge whether cap-sensor 40 is touched.

In this embodiment, square-wave signal generation circuit 10 and capacitance voltage sample circuit 20 are by microprocessor MCU is constituted, and the outfan of square-wave signal generation circuit 10 is the PWM outfan of Micro-processor MCV Mouthful, square-wave signal is pwm signal.The test side of capacitance voltage sample circuit 20 is Micro-processor MCV A/D sample port.Preferably, Micro-processor MCV is single-chip microcomputer.In other embodiments, side Ripple signal generating circuit 10 can utilize independent PWM chip to constitute.Capacitance voltage sample circuit 20 can To utilize existing discrete component to be constituted.

In this embodiment, charge-discharge circuit 30 includes the first diode D1, the second diode D2, the first electricity Resistance R1, the second resistance R2 and the first electric capacity C1.One end of first resistance R1 is with the first diode D1's Negative electrode, the outfan of square-wave signal generation circuit 10 are connected, the other end of the first resistance R1 and the one or two pole The anode of pipe D1, the anode of above-mentioned second diode D2, one end of cap-sensor 40 are connected, electricity Holding the other end ground connection of induced key 40, the negative electrode of the second diode D2 connects capacitance voltage sample circuit 20 Test side, and by the second resistance R2 ground connection, the first electric capacity C1 and the second resistance R2 parallel connection.

In actual application, the button of electronic product often more than one, this capacitance type touch key circuit Can be extended the most easily, only need to increase discharge and recharge accordingly according to actual button demand Circuit 30.

In conjunction with Fig. 1 and Fig. 2, contactless key circuit operation principle is:

1, the PWM port of Micro-processor MCV keeps the pwm signal of output 50% dutycycle.

2, cap-sensor 40 is equivalent to an electric capacity, equivalence when human body does not do the action of key-press input Electric capacity holds the least；When pwm signal is high level, the first diode D1 cut-off, Micro-processor MCV PWM port by the first resistance R1 to this equivalent capacity of cap-sensor 40 charge, work as voltage When Vkey is more than Vad (cap-sensor 40 both end voltage), the second diode D2 conducting, by the Two diode D2 charge to the first electric capacity C1；When pwm signal is low level, the first diode D1 Turning on, the equivalent capacity of the first electric capacity C1 induced key 40 passes through the first diode D1 repid discharge, the Diode ends, and the first electric capacity C1 is discharged by the second resistance R2；Therefore Vad is the voltage of minor fluctuations, And the A/D sample port of its Micro-processor MCV samples the average voltage Voff of its Vad.

3, when human body does the action of key-press input, the medium of the equivalent capacity of cap-sensor 40 is changed Coefficient so that electric capacity quantitative change is big；When pwm signal is high level, the first diode D1 cut-off, micro- The PWM port of processor MCU passes through the first resistance R1 to this equivalent capacity of cap-sensor 40 Charging, when voltage Vkey more than Vad time, second diode D2 conducting, by the second diode D2 to First electric capacity C1 charging；When pwm signal is low level, the first diode D1 conducting, the first electric capacity The equivalent capacity of C1 induced key 40 passes through the first diode D1 repid discharge, and diode ends, the One electric capacity C1 is discharged by the second resistance R2；Therefore Vad is the voltage of minor fluctuations, and its microprocessor The A/D sample port of MCU samples the average voltage Von of its Vad.

4, owing to Von is less than Voff, the electricity that Micro-processor MCV can be sampled by A/D sample port Pressure determines whether key-press input.

This utility model produces square-wave signal by Micro-processor MCV, and in cap-sensor 40 Capacitance voltage signal introduce single-chip microcomputer A/D sample port, calculate electric capacity by Micro-processor MCV The size variation of the voltage signal at induced key 40 two ends, thus the identification of cap-sensor 40 can be realized, Have that circuit is simple, low cost, be easily achieved, high reliability.

The foregoing is only preferred embodiment of the present utility model, not in order to limit this utility model, All any amendment, equivalent and improvement etc. made within spirit of the present utility model and principle, all should Within being included in protection domain of the present utility model.

Claims (6)

1. a key circuit, it is characterised in that include square-wave signal generation circuit, cap-sensor, Capacitance voltage sample circuit and charge-discharge circuit, described charge-discharge circuit is passed through in described cap-sensor one end It is connected with the outfan of described square-wave signal generation circuit, described cap-sensor other end ground connection, and institute State the cap-sensor other end test side by described charge-discharge circuit with described capacitance voltage sample circuit Connect；Described charge-discharge circuit receives the square wave of described square-wave signal generation circuit generation to described capacitive sensing Button carries out discharge and recharge, described capacitance voltage sample circuit detect the voltage pulsation of described cap-sensor with Judge whether described cap-sensor is touched.

2. key circuit as claimed in claim 1, it is characterised in that described square-wave signal generation circuit by Microprocessor is constituted, and the outfan of described square-wave signal generation circuit is the PWM output of described microprocessor Port.

3. key circuit as claimed in claim 2, it is characterised in that described capacitance voltage sample circuit by Described microprocessor is constituted, and the A/D that test side is described microprocessor of described capacitance voltage sample circuit adopts Sample port.

4. key circuit as claimed in claim 2 or claim 3, it is characterised in that described microprocessor is monolithic Machine.

5. the key circuit as described in claim 1,2 or 3, it is characterised in that described charge-discharge circuit Including the first diode, the second diode, the first resistance, the second resistance and the first electric capacity, wherein:

One end of described first resistance and the negative electrode of described first diode, described square-wave signal generation circuit Outfan is connected, the other end of described first resistance and the anode of described first diode, above-mentioned two or two pole The anode of pipe, one end of described cap-sensor are connected, the other end ground connection of described cap-sensor, The negative electrode of described second diode connects the test side of described capacitance voltage sample circuit, and by described second electricity Resistance ground connection, described first electric capacity and described second resistor coupled in parallel.

6. a home appliance, it is characterised in that include the button electricity described in any one of claim 1 to 5 Road.