CN105450203A - Interference filtering device and interference filtering method for rapid on-off mechanical switches - Google Patents
Interference filtering device and interference filtering method for rapid on-off mechanical switches Download PDFInfo
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- CN105450203A CN105450203A CN201510780816.5A CN201510780816A CN105450203A CN 105450203 A CN105450203 A CN 105450203A CN 201510780816 A CN201510780816 A CN 201510780816A CN 105450203 A CN105450203 A CN 105450203A
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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
- H03K17/04—Modifications for accelerating switching
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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
- H03K17/16—Modifications for eliminating interference voltages or currents
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Abstract
The invention provides an interference filtering device and an interference filtering method for rapid on-off mechanical switches. The device comprises a switch, an input circuit, a delay circuit used for outputting control pulse with adjustable delay and pulse width after internal delay under the trigger of a switching signal, a switching circuit, and a sampling and holding circuit. Through the delay circuit and the switching circuit, the sampling and holding circuit is disconnected from the switching signal when the switching signal is under interference, and the sampling and holding circuit and the switching signal are reconnected when the interference signal ends. Therefore, signal delay brought by an ordinary RC filter circuit is avoided, and interference signal filtering is more thorough. The device and the method are used for filtering interference to a switching signal for fast switching on-off, and is especially used in a situation in which multiple switches more sensitive to interference signals are combined through series and parallel connection and the closed switches are identified by detecting the voltage value of the switching signal.
Description
Technical field
The invention belongs to design of electronic circuits and electronic signal process field, particularly relate to a kind of interference filter for quick on-off mechanical switch and method.
Background technology
In electronic product, switch is very general as a kind of man-machine interaction means application.Conventional switch mostly is mechanical switch, due to the elastic reaction of mechanical contact, press with in dispose procedure at it, all inevitably produce shake, cause switching signal can not stably connect when switch closes at once, can not disconnect immediately when switch discharges, can there is a series of shake when switch closes and discharge in signal waveform.Under normal circumstances, the break-make frequency of hand switch is roughly lower than 10 times/second, the time interval of twice switching manipulation is not less than 100 milliseconds, and the signal jitter time that switch from fluttering causes, can the shake of filtered signal preferably by simple RC filtering generally at 10 milliseconds ~ 20 milliseconds.But for the switching signal that the break-make frequency that similar electricity drum is such is higher detects, the beating frequency of specialty drummer can easily more than 20 ~ 30 time/second, the time interval of twice switch motion may lower than 30 ~ 50mS, because the interval time of switching signal is close with the duration of shaking the interference signal caused, traditional RC filter circuit seems helpless to such interference signal.In addition, for thin film switch, due to the piezoelectric effect of film, when impacting thin film switch, film shakes the piezoelectric signal produced and can be added in switching signal, makes signal disturbing more serious.Especially for the application that the size of multiple switch being carried out connection in series-parallel group merga pass sense switch signal voltage value identifies closed switch, switching signal becomes more responsive to suffered interference.
Be in the utility model patent of 201320109704.3 at application number, disclose a kind of button Anti-shaking circuit, by RC filtering, switching signal is processed, the circuit structure of this button Anti-shaking circuit as shown in Figure 1, its operation principle process is as follows: when the switch is closed, electric capacity C0 shorted to earth, the voltage at electric capacity C0 two ends reduces to 0 fast because directly discharging over the ground; When switching circuit disconnects, electric capacity C0 charges through resistance R0, and electric capacity C0 both end voltage slowly rises and can not recover high voltage immediately.Can be changed the charge constant of electric capacity C0 by the parameter of adjusting resistance R0 and electric capacity C0, thus effective filtering key jitter is to the interference of signal.Foregoing circuit is used for the interference filter to the lower switching signal of common break-make frequency, but is not used in the interference filter to the higher switching signal of break-make frequency, because the discharge and recharge of electric capacity causes the delay of switching signal, and the detection of impact to subsequent switching signals.
Summary of the invention
The shortcoming of prior art in view of the above, the object of the present invention is to provide a kind of interference filter for quick on-off mechanical switch and method, the delay of switching signal is caused for solving filtering technique of the prior art due to capacitor charge and discharge, and the problem of impact to the detection of follow-up stroke signal.
For achieving the above object and other relevant objects, the invention provides a kind of interference filter for quick on-off mechanical switch, comprising: switch, for generation of switching signal; Delay circuit, under the triggering of described switching signal, exports time delay and all adjustable control impuls of pulsewidth after internal delay time; Switching circuit, is connected to described delay circuit, for realizing break-make under the control of described control impuls; And sampling hold circuit, be connected to described switching circuit, for when switching circuit closes, carry out quick sampling to follow the tracks of the change of input signal to input signal, when switching circuit disconnects, output voltage remains unchanged.
As a kind of preferred version of the interference filter for quick on-off mechanical switch of the present invention, described switch comprises mechanical switch, and its first end ground connection, the second end is connected to the signal input part of described input circuit.
As a kind of preferred version of the interference filter for quick on-off mechanical switch of the present invention, described interference filter also comprises input circuit, is connected between described switch and described delay circuit, for providing impedance matching for described switching signal.
Further, described input circuit comprises pull-up resistor and the first operational amplifier, wherein, the first end of described pull-up resistor is connected with power supply VCC, second end is connected with the second end of described switch and the in-phase input end of the first operational amplifier, and the inverting input of described first operational amplifier is connected with output.
As a kind of preferred version of the interference filter for quick on-off mechanical switch of the present invention, described delay circuit comprises circuits for triggering, time delay charge-discharge circuit and time delayed signal shaping circuit.
Preferably, described circuits for triggering comprise triode, the first resistance and the second resistance, wherein, the described first end of the first resistance is connected with the emitter of triode and power supply VCC, second end is connected with the base stage of triode and the first end of the second resistance, and the second end of described second resistance is connected with the output of input circuit and the input of switching circuit.
Preferably, described time delay charge-discharge circuit comprises the 3rd resistance, the first electric capacity and the 4th resistance, wherein, the first end of described 3rd resistance is connected with the collector electrode of described triode, the input of the second end and the first pole of the first electric capacity, the first end of the 4th resistance and described time delayed signal shaping circuit is connected, the second pole of described first electric capacity and the second end ground connection of the 4th resistance.
Preferably, described time delayed signal shaping circuit comprises the first not gate and the second not gate, wherein, the input of described first not gate is connected with the second end of described 3rd resistance, output is connected with the input of the second not gate, the output of described second not gate is connected with switching circuit control end, and it exports the break-make being used for control switch circuit.
As a kind of preferred version of the interference filter for quick on-off mechanical switch of the present invention, described switching circuit comprises PMOS, the grid of described PMOS is connected with the output of delay circuit, source electrode is connected with second end of the output of input circuit with the second resistance in delay circuit, drains to be connected with the input of sampling hold circuit.
As a kind of preferred version of the interference filter for quick on-off mechanical switch of the present invention, described sampling hold circuit comprises the second electric capacity and the second operational amplifier, wherein, first pole of described second electric capacity is connected with the in-phase input end of the second operational amplifier and the output of switching circuit, the inverting input of described second operational amplifier is connected with output, and as signal output part.
As a kind of preferred version of the interference filter for quick on-off mechanical switch of the present invention, described switch comprises several mechanical switchs and several divider resistances, the first end ground connection of several mechanical switchs described, several divider resistances described are connected to the second end of adjacent two mechanical switchs successively.
The principle of the interference filter for quick on-off mechanical switch of the present invention is: when described switch is in off-state, switching signal keeps high level, the output signal of described delay circuit controls described switching circuit and is in conducting state, makes described sampling hold circuit can follow the tracks of the change of switching signal fast.When the switch is closed, switching signal, by high step-down, because interference signal lags behind useful signal (delayed about 0.2 millisecond of such as piezoelectricity jam-to-signal switching signal) in time, makes interference signal occur after switching signal step-down.In switching signal step-down process, described sampling hold circuit follows the tracks of the change of switching signal fast, and before interference signal occurs, described switching circuit disconnects by the control of described delay circuit output signal, makes the magnitude of voltage that described sampling hold circuit finally fixed when described switching circuit disconnects.At switching circuit off period, the output signal of described sampling hold circuit remains unchanged, thus the impact of interference signal in avoiding switching make and break process, until interference signal terminates, when the output signal of described delay circuit recovers low level, described switching circuit closes again, and described sampling hold circuit recovers the quick tracking to switching signal change again, prepares the filtering process to interference signal in switch on and off process next time.
The present invention also provides a kind of interference filter method for quick on-off mechanical switch, comprise step: 1) when the switch is closed, switching signal is by high step-down, trigger described delay circuit its output signal after experiencing first time of delay that can set to be uprised by low, and then after experiencing another second time of delay that can set, it outputs signal by high step-down; 2) during described delay circuit output low level by described switching circuit conducting, make described sampling hold circuit be followed the tracks of the change of switching signal fast; Described switching circuit disconnects when exporting high level by described delay circuit, described sampling hold circuit and switching signal is disconnected and keeps output voltage constant; 3) described first time of delay and the second time of delay is adjusted, make described switching circuit after switch is closed and disconnect before interference signal appearance, then after switch disconnects and interference signal is closed after terminating, thus make the output signal of described sampling hold circuit from the impact of interference signal lagging behind switching signal the time.
As a kind of preferred version of the interference filter method for quick on-off mechanical switch of the present invention, series-parallel interference filter is carried out for comprising multiple mechanical switch, when wherein one or more switches close, switching signal is by high step-down, interference signal lags behind the change of switching signal, in the process of switching signal step-down, described sampling hold circuit follows the tracks of the change of switching signal fast, and before interference signal occurs, described switching circuit disconnects by the control of described delay circuit output signal, make the magnitude of voltage that described sampling hold circuit finally fixed when described switching circuit disconnects, at switching circuit off period, the output signal of described sampling hold circuit remains unchanged, thus the impact of interference signal in avoiding switching make and break process.Until interference signal terminates, when the output signal of described delay circuit recovers low level, described switching circuit closes again, and described sampling hold circuit recovers the quick tracking to switching signal change again, prepares the filtering process to interference signal in switch on and off process next time.
Further, described in described switching circuit off period, the output voltage of sampling hold circuit remains that to close corresponding magnitude of voltage with described one or more switch constant, is judged by the magnitude of voltage detecting output signal and identifies switch is closed.
As mentioned above, interference filter for quick on-off mechanical switch of the present invention and method, there is following beneficial effect: interference signal filter method provided by the invention, by delay circuit and switching circuit, when switching signal is disturbed, sampling hold circuit and switching signal are disconnected, at the end of interference signal, recover the connection of sampling hold circuit and switching signal simultaneously, avoid the signal delay that common RC filter circuit brings, simultaneously also more thorough to the filtration of interference signal, filter for implementing interference to the switching signal of quick on-off, be particularly useful for the situation that the size of multiple switch being carried out connection in series-parallel group merga pass sense switch signal voltage value more responsive to interference signal identifies closed switch.
Accompanying drawing explanation
Fig. 1 is shown as RC filter circuit principle schematic of the prior art.
Fig. 2 is shown as the circuit theory schematic diagram of the interference filter for quick on-off mechanical switch in the embodiment of the present invention 1.
Fig. 3 is shown as the circuit theory schematic diagram of the interference filter for quick on-off mechanical switch in the embodiment of the present invention 2.
Fig. 4 is shown as signal undisturbed oscillogram when little dynamics is beaten, and wherein, the curve being positioned at top represents undressed original switching signal, and the curve below being positioned at is the output signal after anti-interference process.
Oscillogram when Fig. 5 is shown as that when great dynamics beats, signal is interfered, wherein, the curve being positioned at top represents undressed original switching signal, and the curve being positioned at below is the output signal after anti-interference process.
Fig. 6 is shown as the waveform detail view that mechanical switch closes moment, and wherein, the curve being positioned at top represents undressed original switching signal, and the curve below being positioned at is the output signal after anti-interference process.
Element numbers explanation
100 switches
101 mechanical switchs
200 input circuits
201 pull-up resistors
202 first operational amplifiers
300 delay circuits
301 first resistance
302 second resistance
303 triodes
304 the 3rd resistance
305 first electric capacity
306 the 4th resistance
307 first not gates
308 second not gates
400 switching circuits
401PMOS manages
500 sampling hold circuits
501 second electric capacity
502 second operational amplifiers
Embodiment
Below by way of specific instantiation, embodiments of the present invention are described, those skilled in the art the content disclosed by this specification can understand other advantages of the present invention and effect easily.The present invention can also be implemented or be applied by embodiments different in addition, and the every details in this specification also can based on different viewpoints and application, carries out various modification or change not deviating under spirit of the present invention.
Refer to Fig. 2 ~ Fig. 6.It should be noted that, the diagram provided in the present embodiment only illustrates basic conception of the present invention in a schematic way, then only the assembly relevant with the present invention is shown in diagram but not component count, shape and size when implementing according to reality is drawn, it is actual when implementing, and the kenel of each assembly, quantity and ratio can be a kind of change arbitrarily, and its assembly layout kenel also may be more complicated.
Embodiment 1
As shown in Figure 2, the present embodiment provides a kind of interference filter for quick on-off mechanical switch, comprising: switch 100, for generation of switching signal; Input circuit 200, is connected to described switch 100, for providing impedance matching for described switching signal; Delay circuit 300, is connected to described input circuit 200, under the triggering of described switching signal, exports time delay and all adjustable control impuls of pulsewidth after internal delay time; Switching circuit 400, is connected to described delay circuit 300, for realizing break-make under the control of described control impuls; And sampling hold circuit 500, be connected to described switching circuit 400, for when switching circuit 400 closes, carry out quick sampling to follow the tracks of the change of input signal to input signal, when switching circuit 400 disconnects, output voltage remains unchanged.
As shown in Figure 2, described switch 100 comprises mechanical switch 101, its first end ground connection, and the second end is connected to the signal input part of described input circuit 200.Due to the pull-up effect of the pull-up resistor 201 in input circuit 200, the switching signal on the other end of switch 100 will keep high level.When switch 100 closes, switching signal becomes low level from high level, and recovers high level after switch 100 disconnects.
As shown in Figure 2, described input circuit 200 comprises pull-up resistor 201 and the first operational amplifier 202, wherein, the first end of described pull-up resistor 201 is connected with power supply VCC, second end is connected with the second end of described switch 100 and the in-phase input end of the first operational amplifier 202, and the inverting input of described first operational amplifier 202 is connected with output.Described input circuit 200 is generally used for, for input signal provides impedance matching, being connected into the form of voltage follower in the present embodiment.When switch 100 closes, the input of the first operational amplifier 202 becomes low level, and its output also becomes 0V thereupon, when switch 100 disconnects, the input of the first operational amplifier 202 becomes high level, and its output also exports high level thereupon, is elevated to the magnitude of voltage close to VCC.Certainly, operational amplifier in described input circuit 200 is not limited to the connected mode of described voltage follower, also can being other the circuit form realizing impedance matching, without the need to carrying out impedance matching when, described operational amplifier directly being saved even.
As shown in Figure 2, described delay circuit 300 comprises circuits for triggering, time delay charge-discharge circuit and time delayed signal shaping circuit.
In the present embodiment, described circuits for triggering comprise triode 303, first resistance 301 and the second resistance 302, wherein, the described first end of the first resistance 301 is connected with the emitter of triode 303 and power supply VCC, second end is connected with the base stage of triode 303 and the first end of the second resistance 302, and described second end of the second resistance 302 is connected with the input of the output of input circuit 200 and switching circuit 400.Described time delay charge-discharge circuit comprises the 3rd resistance 304, first electric capacity 305 and the 4th resistance 306, wherein, the first end of described 3rd resistance 304 is connected with the collector electrode of described triode 303, the input of the second end and the first pole of the first electric capacity 305, the first end of the 4th resistance 306 and described time delayed signal shaping circuit is connected, the second pole of described first electric capacity 305 and the second end ground connection of the 4th resistance 306.Described time delayed signal shaping circuit comprises the first not gate 307 and the second not gate 308, wherein, the input of described first not gate 307 is connected with the second end of described 3rd resistance 304, output is connected with the input of the second not gate 308, the output of described second not gate 308 is connected with switching circuit 400 control end, and it exports the break-make being used for control switch circuit 400.In the present embodiment, described triode 303 is PNP triode 303.
The course of work of described delay circuit 300 is: when switch 100 closes, the output voltage step-down of the first operational amplifier 202 in input circuit 200, trigger triode 303 conducting, make supply voltage VCC start charging by triode 303 and the 3rd resistance 304 to the first electric capacity 305, its charge constant t1 is determined by the product of the 3rd resistance 304 and the first electric capacity 305.When switch 100 disconnects, the output voltage of the first operational amplifier 202 recovers high level, and triode 303 ends, and the first electric capacity 305 is discharged by the 4th resistance 306, and its discharge time constant t2 is determined by the product of the 4th resistance 306 and the first electric capacity 305.Charge constant t1 is for adjusting PMOS 401 turn-off delay time closed relative to switch 100, and switching circuit 400 closes rear at switch 100 and disconnects before interference signal appearance to select suitable charge constant t1 to ensure; The turn on delay time that discharge time constant t2 disconnects relative to switch 100 for adjusting PMOS 401, switching circuit 400 is after switch 100 disconnects and interference signal is closed after terminating to select suitable discharge time constant t2 to ensure.
Certainly, circuits for triggering in described delay circuit 300 are not limited to the circuit form of PNP triode 303, can be other can detect that when switch 100 closes the output voltage of the first operational amplifier 202 changes and controls the circuit form that the first electric capacity 305 carries out discharge and recharge; The discharge and recharge signal transformation circuit of described first electric capacity 305 is also not limited to the first not gate 307 and connects the circuit form of the second not gate 308.
As shown in Figure 2, described switching circuit 400 comprises PMOS 401, the grid of described PMOS 401 is connected with the output of delay circuit 300, source electrode is connected with second end of the output of input circuit 200 with the second resistance 302 in delay circuit 300, drains to be connected with the input of sampling hold circuit 500.The conducting when delay circuit 300 output low level of described PMOS 401 makes sample circuit sample to the switching signal that input circuit 200 exports, and disconnects the voltage on the second electric capacity 501 in sampling hold circuit 500 is kept when delay circuit 300 exports high level.Certainly, the switch in described switching circuit 400 is not limited to PMOS 401, also can be NMOS tube and coordinate the corresponding adjustment of grid control signal, or selecting other switch element according to actual conditions.
As shown in Figure 2, described sampling hold circuit 500 comprises the second electric capacity 501 and the second operational amplifier 502, wherein, first pole of described second electric capacity 501 is connected with the in-phase input end of the second operational amplifier 502 and the output of switching circuit 400, the inverting input of described second operational amplifier 502 is connected with output, and as signal output part.When switching circuit 400 conducting, the switching signal that described second electric capacity 501 pairs of input circuits 200 export is sampled, thus follows the tracks of the change of switching signal fast; When switching circuit 400 disconnects, the voltage of described electric capacity remains unchanged.Described second operational amplifier 502 serves as voltage follower herein, the voltage on the second electric capacity 501 is exported to output signal VOUT.Certainly, the second electric capacity 501 in described sampling hold circuit 500 and the circuit form of voltage follower being not limited to the second operational amplifier 502 between output signal and forming also can be other circuit forms that the discharge and recharge signal on the second electric capacity 501 can be converted to the output signal with certain driving force.
In the present embodiment, described interference filter is applied to electronic drum, the electronic drum of the present embodiment comprises drum surface and is positioned at the mechanical switch below drum surface, further, described mechanical switch is the switch film be arranged at below drum surface, knocks by drum rod the break-make that drum surface can realize described switch film.Particularly, the principle of the interference filter for quick on-off mechanical switch of the present embodiment is: when described switch 100 is in off-state, switching signal keeps high level, the output signal of described delay circuit 300 controls described switching circuit 400 and is in conducting state, makes described sampling hold circuit 500 can follow the tracks of the change of switching signal fast.When described switch 100 closed (namely rouse rod and knock drum surface), switching signal is by high step-down, switching circuit conducting, sampling hold circuit 500 pairs of switching signals are followed the tracks of fast, because interference signal lags behind useful signal (delayed about 0.2 millisecond of such as piezoelectricity jam-to-signal switching signal) in time, interference signal is occurred after switching signal step-down.In switching signal step-down process, described sampling hold circuit 500 follows the tracks of the change of switching signal fast, through the first delay time and interference signal occur before, described switching circuit 400 disconnects by the control of described delay circuit 300 output signal, makes the magnitude of voltage that described sampling hold circuit 500 finally fixed when described switching circuit 400 disconnects.(namely rouse rod and leave drum surface) period is disconnected at switching circuit 400, the output signal of described sampling hold circuit 500 remains unchanged, thus the impact of interference signal in avoiding switching make and break process, until the output signal of (interference signal terminates) described delay circuit 300 recovers low level after the second delay time, described switching circuit 400 closes again, described sampling hold circuit 500 recovers the quick tracking to switching signal change again, prepares the filtering process to interference signal in switch on and off process next time.What needs further illustrated is, the time delay of control impuls that in the present embodiment, delay circuit 300 realizes and pulsewidth all adjustable, time delay is adjustable, and to refer to the first delay time (as 0.2 millisecond) adjustable, and it is adjustable that adjustable pulse width refers to the second delay time (as 10 milliseconds).
The present invention also provides a kind of interference filter method for quick on-off mechanical switch, comprise step: 1) when switch 100 closes, switching signal is by high step-down, the output signal of described input circuit 200 is also by high step-down, and trigger described delay circuit 300 its output signal after experiencing first time of delay that can set and uprised by low, and then after experiencing another second time of delay that can set, it outputs signal by high step-down; 2) during described delay circuit 300 output low level by the conducting of described switching circuit 400, make described sampling hold circuit 500 be followed the tracks of the change of switching signal fast; Described switching circuit 400 disconnects when exporting high level by described delay circuit 300, makes described sampling hold circuit 500 disconnect with switching signal and keep output voltage constant; 3) described first time of delay and the second time of delay is adjusted, make described switching circuit 400 after switch 100 is closed and disconnect before interference signal appearance, then after switch 100 disconnects and interference signal is closed after terminating, thus make the output signal of described sampling hold circuit 500 from the impact of interference signal lagging behind switching signal the time.
Fig. 4 ~ Fig. 6 is shown as the contrast oscillogram before and after interference signal process, and wherein, Fig. 4 is shown as signal undisturbed oscillogram when little dynamics is beaten, oscillogram when Fig. 5 is shown as that when great dynamics beats, signal is interfered.In Fig. 4 ~ Fig. 6, the curve being positioned at top represents undressed original switching signal, and the curve below being positioned at is the output signal after anti-interference process.Therefrom Fig. 5 can find out, when input signal is interfered, the output signal after process of the present invention is consistent with the magnitude of voltage fixed time undisturbed in Fig. 4.
As shown in Figure 5, the time point that trailing edge corresponding switch circuit in the signal output waveform of lower curve disconnects, thereafter output signal keeps voltage sample value constant, so not by the impact of the interference voltage in input signal, remain constant, until after experiencing for the second time of delay, at the rising edge place of output waveform, the time point that corresponding switch circuit closes again, output voltage recovers the tracking to input voltage again.
Fig. 6 is shown as the waveform detail view that mechanical switch closes moment, and as seen from the figure, at input signal step-down and after experiencing for the first time of delay and being about 0.1mS, output signal fixes as switching circuit disconnects the sample voltage value of moment.
Embodiment 2
As shown in Figure 3, the present embodiment provides a kind of interference filter for quick on-off mechanical switch, its basic circuit structure is as embodiment 1, wherein, described switch 100 comprises several mechanical switchs and several divider resistances, the first end ground connection of several mechanical switchs described, several divider resistances described are connected to the second end of adjacent two mechanical switchs successively.
Particularly, in the present embodiment, described switch comprises the first mechanical switch 101, second mechanical switch 102 and the 3rd mechanical switch 103, and the first divider resistance 104 and the second divider resistance 105.Wherein, first divider resistance 104 and the second divider resistance 105 form with the pull-up resistor 201 in input circuit 200 dividing potential drop of connecting, and when such first mechanical switch 101, second mechanical switch 102 and the 3rd mechanical switch 103 each self-closing, corresponding switching signal will obtain different magnitudes of voltage.When one of them switch closes, the output voltage of input circuit 200 will rapidly drop to the magnitude of voltage Vin therewith corresponding to switch, sampling hold circuit 500 due to switching circuit 400 be in conducting state also Rapid Variable Design to Vin.Simultaneously, lower general who has surrendered's Time delay circuit 300 of the output voltage of input circuit 200 after the first time of delay t1 before interference signal occurs output level uprised by low, switching circuit 400 is disconnected, thus makes the output voltage of sampling hold circuit 500 fix on magnitude of voltage Vin; When above-mentioned switch disconnects and after the second time of delay t2, the output of delay circuit 300 recovers low level, make switching circuit 400 recover conducting state, thus sampling hold circuit 500 also returns to the high level consistent with input circuit 200 output.Like this, at switching circuit 400 off period, it is constant that output voltage VO UT is maintained magnitude of voltage Vin, thus avoid the impact of interference signal.
Particularly, in the present embodiment, above-mentioned interference filter is applied to electronic drum, the electronic drum of the present embodiment comprises 3 thin film switches, first thin film switch is arranged at small cymbals sheet or drum central lower, second thin film switch is arranged at below small cymbals sheet or drum face, and the 3rd thin film switch is arranged at below the edge of small cymbals sheet or drum.
The present embodiment also provides a kind of interference filter method for quick on-off mechanical switch, its basic step is as embodiment 1, wherein, series-parallel interference filter is carried out for comprising multiple mechanical switch, when wherein one or more switches close, switching signal is by high step-down, interference signal lags behind the change of switching signal, in the process of switching signal step-down, described employing holding circuit follows the tracks of the change of switching signal fast, and before interference signal occurs, described switching circuit 400 disconnects by the control of described delay circuit 300 output signal, make the magnitude of voltage that described sampling hold circuit 500 finally fixed when described switching circuit 400 disconnects, at switching circuit 400 off period, the output signal of described sampling hold circuit 500 remains unchanged, thus the impact of interference signal in avoiding switching make and break process.Until interference signal terminates, when the output signal of described delay circuit 300 recovers low level, described switching circuit 400 closes again, and described sampling hold circuit 500 recovers the quick tracking to switching signal change again, prepares the filtering process to interference signal in switch on and off process next time.Described in described switching circuit 400 off period, the output voltage of sampling hold circuit 500 remains that to close corresponding magnitude of voltage with described one or more switch constant, is judged by the magnitude of voltage detecting output signal and identifies switch is closed.Particularly, " judgement " refers to and has judged whether switch closed (namely whether exist knock drum cause thin film switch is closed produces switching signal), " identification " refers to and identifies which switch closes (be namely that the thin film switch of drum surface position closes, or the thin film switch of drum position, limit being closed etc.).
Certainly, in other embodiments, the quantity of described switch is closed and is not limited to 3, it combines the connected mode adopted and is also not limited to parallel way, also series system is not limited between the multiple divider resistances coordinated with it, can according to practical application need adopt different connected mode, to reach the object obtaining different magnitudes of voltage when different switch closes from the output of switch
As mentioned above, the invention provides a kind of interference filter for quick on-off mechanical switch and method, described interference filter, comprising: switch 100, for generation of switching signal; Input circuit 200, is connected to described switch 100, for providing impedance matching for described switching signal; Delay circuit 300, is connected to described input circuit 200, under the triggering of described switching signal, exports time delay and all adjustable control impuls of pulsewidth after internal delay time; Switching circuit 400, is connected to described delay circuit 300, for realizing break-make under the control of described control impuls; And sampling hold circuit 500, be connected to described switching circuit 400, for when switching circuit 400 closes, carry out quick sampling to follow the tracks of the change of input signal to input signal, when switching circuit 400 disconnects, output voltage remains unchanged.Interference signal filter method provided by the invention, by delay circuit 300 and switching circuit 400, when switching signal is disturbed, sampling hold circuit 500 and switching signal are disconnected, at the end of interference signal, recover the connection of sampling hold circuit 500 and switching signal simultaneously, avoid the signal delay that common RC filter circuit brings, simultaneously also more thorough to the filtration of interference signal, filter for implementing interference to the switching signal of quick on-off, be particularly useful for the situation that the size of multiple switch being carried out connection in series-parallel group merga pass sense switch signal voltage value more responsive to interference signal identifies closed switch.So the present invention effectively overcomes various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all without prejudice under spirit of the present invention and category, can modify above-described embodiment or changes.Therefore, such as have in art usually know the knowledgeable do not depart from complete under disclosed spirit and technological thought all equivalence modify or change, must be contained by claim of the present invention.
Claims (14)
1., for an interference filter for quick on-off mechanical switch, it is characterized in that, comprising:
Switch, for generation of switching signal;
Delay circuit, under the triggering of described switching signal, exports time delay and all adjustable control impuls of pulsewidth after internal delay time;
Switching circuit, is connected to described delay circuit, for realizing break-make under the control of described control impuls;
Sampling hold circuit, is connected to described switching circuit, and for when switching circuit closes, carry out quick sampling to follow the tracks of the change of input signal to input signal, when switching circuit disconnects, output voltage remains unchanged.
2. the interference filter for quick on-off mechanical switch according to claim 1, is characterized in that: described switch comprises mechanical switch, and its first end ground connection, the second end is connected to the signal input part of described input circuit.
3. the interference filter for quick on-off mechanical switch according to claim 1, it is characterized in that: described interference filter also comprises input circuit, be connected between described switch and described delay circuit, for providing impedance matching for described switching signal.
4. the interference filter for quick on-off mechanical switch according to claim 3, it is characterized in that: described input circuit comprises pull-up resistor and the first operational amplifier, wherein, the first end of described pull-up resistor is connected with power supply VCC, second end is connected with the second end of described switch and the in-phase input end of the first operational amplifier, and the inverting input of described first operational amplifier is connected with output.
5. the interference filter for quick on-off mechanical switch according to claim 1, is characterized in that: described delay circuit comprises circuits for triggering, time delay charge-discharge circuit and time delayed signal shaping circuit.
6. the interference filter for quick on-off mechanical switch according to claim 5, it is characterized in that: described circuits for triggering comprise triode, the first resistance and the second resistance, wherein, the described first end of the first resistance is connected with the emitter of triode and power supply VCC, second end is connected with the base stage of triode and the first end of the second resistance, and the second end of described second resistance is connected with the output of input circuit and the input of switching circuit.
7. the interference filter for quick on-off mechanical switch according to claim 6, it is characterized in that: described time delay charge-discharge circuit comprises the 3rd resistance, the first electric capacity and the 4th resistance, wherein, the first end of described 3rd resistance is connected with the collector electrode of described triode, the input of the second end and the first pole of the first electric capacity, the first end of the 4th resistance and described time delayed signal shaping circuit is connected, the second pole of described first electric capacity and the second end ground connection of the 4th resistance.
8. the interference filter for quick on-off mechanical switch according to claim 7, it is characterized in that: described time delayed signal shaping circuit comprises the first not gate and the second not gate, wherein, the input of described first not gate is connected with the second end of described 3rd resistance, output is connected with the input of the second not gate, the output of described second not gate is connected with switching circuit control end, and it exports the break-make being used for control switch circuit.
9. the interference filter for quick on-off mechanical switch according to claim 8, it is characterized in that: described switching circuit comprises PMOS, the grid of described PMOS is connected with the output of delay circuit, source electrode is connected with second end of the output of input circuit with the second resistance in delay circuit, drains to be connected with the input of sampling hold circuit.
10. the interference filter for quick on-off mechanical switch according to claim 1, it is characterized in that: described sampling hold circuit comprises the second electric capacity and the second operational amplifier, wherein, first pole of described second electric capacity is connected with the in-phase input end of the second operational amplifier and the output of switching circuit, the inverting input of described second operational amplifier is connected with output, and as signal output part.
The 11. interference filters for quick on-off mechanical switch according to claim 1, it is characterized in that: described switch comprises several mechanical switchs and several divider resistances, the first end ground connection of several mechanical switchs described, several divider resistances described are connected to the second end of adjacent two mechanical switchs successively.
The interference filter method of 12. 1 kinds of interference filters for quick on-off mechanical switch as described in claim 1 ~ 11 any one, is characterized in that, comprise step:
1) when the switch is closed, switching signal, by high step-down, triggers described delay circuit its output signal after experiencing first time of delay that can set and uprised by low, and then after experiencing another second time of delay that can set, it outputs signal by high step-down;
2) during described delay circuit output low level by described switching circuit conducting, make described sampling hold circuit be followed the tracks of the change of switching signal fast; Described switching circuit disconnects when exporting high level by described delay circuit, described sampling hold circuit and switching signal is disconnected and keeps output voltage constant;
3) described first time of delay and the second time of delay is adjusted, make described switching circuit after switch is closed and disconnect before interference signal appearance, then after switch disconnects and interference signal is closed after terminating, thus make the output signal of described sampling hold circuit from the impact of interference signal lagging behind switching signal the time.
The interference filter method of the 13. interference filters for quick on-off mechanical switch according to claim 12, it is characterized in that: carry out series-parallel interference filter for comprising multiple mechanical switch, when wherein one or more switches close, switching signal is by high step-down, interference signal lags behind the change of switching signal, in the process of switching signal step-down, described sampling hold circuit follows the tracks of the change of switching signal fast, and before interference signal occurs, described switching circuit disconnects by the control of described delay circuit output signal, make the magnitude of voltage that described sampling hold circuit finally fixed when described switching circuit disconnects, at switching circuit off period, the output signal of described sampling hold circuit remains unchanged, thus the impact of interference signal in avoiding switching make and break process.
The interference filter method of the 14. interference filters for quick on-off mechanical switch according to claim 13, it is characterized in that: the output voltage of sampling hold circuit remains that to close corresponding magnitude of voltage with described one or more switch constant described in described switching circuit off period, judge by the magnitude of voltage detecting output signal switch is closed and identifies.
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