CN104124953A - High-precision capacitive switch - Google Patents
High-precision capacitive switch Download PDFInfo
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- CN104124953A CN104124953A CN201310148319.4A CN201310148319A CN104124953A CN 104124953 A CN104124953 A CN 104124953A CN 201310148319 A CN201310148319 A CN 201310148319A CN 104124953 A CN104124953 A CN 104124953A
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Abstract
A high-precision capacitive switch is disclosed. The capacitive switch contains a drive circuit, a detection circuit, a reference circuit and a judgment unit. The drive circuit inputs the same drive signal to the detection circuit and the reference circuit. The detection circuit is used for detecting contact according to changes in capacitance. A first signal is outputted when the contact is not detected and a second signal is outputted when the contact is detected. The reference circuit is a duplicated circuit of the detection circuit and is used for outputting the first signal. The judgment unit judges phase difference between the second signal of the detection circuit and the first signal of the reference circuit.
Description
Technical field
The present invention is relevant a kind of switching device, and more relevant a kind of reference circuit that arranges is to improve the capacitance-type switch of accuracy of detection.
Background technology
Traditionally, switch element is used mechanical switch to detect pressing or opening and closing of user.Yet traditional mechanical switch is after frequent use, often there will be and make delay of response or because flexible member is tired, cause the situation that cannot operate because of poor electrical contact.
Thereby industry proposed capacitance-type switch, it is by detecting the capacitance variations causing because of touching, for example, detect concussion frequency shift or charging interval to change, and judges whereby whether touch event occurs.Yet known capacitance testing circuit can may produce electrical skew because of the change of processing procedure, operating voltage and temperature, in when operation, may there is the situation of erroneous judgement and reduce performance accuracy.
In view of this, the present invention also proposes a kind of capacitance-type switch, and its testing result can be compared with the output of reference circuit, gets rid of whereby the electrical skew that processing procedure and operating environment factor cause, thereby has higher accuracy of detection.
Summary of the invention
The invention provides a kind of capacitance-type switch, it can get rid of the electrical skew causing because of processing procedure, operating voltage and temperature, improves whereby accuracy of detection.
The invention provides a kind of capacitance-type switch, it can compare the output signal of testing circuit and reference circuit, improves whereby accuracy of detection.
The invention provides a kind of capacitance-type switch, this kind of capacitance-type switch comprise drive circuit, at least one testing circuit, reference circuit with and judging unit.Described drive circuit is in order to output drive signal.Described testing circuit, in order to detect contact according to capacitance variations, is not exported first signal and according to described driving signal, export secondary signal when described contact being detected according to described driving signal when described contact being detected.Described reference circuit is in order to export described first signal according to described driving signal; Wherein, the duplicate circuit that described reference circuit is described testing circuit.Described judging unit judges signal in order to the phase difference output according to the described first signal of the described secondary signal of described testing circuit and described reference circuit.
The present invention also provides capacitance-type switch, and this capacitance-type switch comprises drive circuit, the first testing circuit, the second testing circuit, the first judging unit and the second judging unit.Described drive circuit is in order to output drive signal.Described the first testing circuit and described the second testing circuit be duplicate circuit and in order to detect and contact according to capacitance variations each other, when described contact being detected, according to described driving signal, exports first signal and according to described driving signal, export secondary signal when described contact being detected.Described the first judging unit judges signal in order to the first-phase potential difference output first according to the described first signal of the described secondary signal of described the first testing circuit and described the second testing circuit.Described the second judging unit judges signal in order to the second-phase potential difference output second according to the described first signal of the described secondary signal of described the second testing circuit and described the first testing circuit.
The present invention also provides a kind of capacitance-type switch, and this capacitance-type switch comprises control unit, at least one testing circuit, reference circuit and judging unit.Described control unit is in order to output drive signal.Described testing circuit in order to according to capacitance variations, detect contact and according to described driving signal and described capacitance variations in different time output detection signal rising edge or trailing edge.Described reference circuit is in order to export reference signal rising edge or trailing edge according to described driving signal; Wherein, the duplicate circuit that described reference circuit is described testing circuit.Described judging unit judges the phase difference of described detection signal rising edge and described reference signal rising edge or described detection signal trailing edge and described reference signal trailing edge; Wherein, described control unit is also according to the comparative result output control signal of described phase difference and threshold value.
In one embodiment, described judging unit, described the first judging unit are to comprise time-to-digit converter, phase detectors, d type flip flop or AND gate with described the second judging unit, to export different judgement signals.
In one embodiment, described testing circuit, described the first testing circuit, described the second testing circuit and described reference circuit comprise delay amplifying circuit, and this delay amplifying circuit is in order to amplify the described phase difference producing because of contact.
In one embodiment, described testing circuit and described reference circuit comprise comparing unit, and this comparing unit is in order to be converted to square-wave signal by described first signal and described secondary signal; Wherein, described comparing unit for example can be slicer, reverser or buffer.
In one embodiment, described drive circuit can be incorporated into control unit, and described control unit is in order to export control signal to control electronic installation according to described judgement signal.
In one embodiment, described capacitance-type switch can comprise conducting element (conductive element), and this conducting element is used for user's contact and described conducting element and is coupled to described Detection capacitance.Whereby, when contacting described conducting element, user can change total capacitance value to change the output signal of testing circuit.In another embodiment, user also can directly contact electric capacity that described testing circuit comprises to cause capacitance variations.
In the capacitance-type switch of the embodiment of the present invention, due to described testing circuit and described reference circuit duplicate circuit each other, therefore all identical for the electrical variation of processing procedure and operating environment.Therefore, the output signal of described testing circuit is compared to judge with the output signal of described reference circuit the event of contact, can effectively reduce judge by accident and increase judgement precision.
For allow above and other object of the present invention, feature and advantage can be more obvious, below will coordinate appended diagram, be described in detail as follows.In addition,, in explanation of the present invention, identical member is to represent with identical symbol, at this, first states clearly.
Accompanying drawing explanation
Fig. 1 shows the block diagram of the capacitance-type switch of first embodiment of the invention;
Fig. 2 A-2C shows the running schematic diagram of the capacitance-type switch of Fig. 1;
Fig. 3 shows another block diagram of the capacitance-type switch of first embodiment of the invention, and it comprises comparing unit;
Fig. 4 shows the block diagram of the capacitance-type switch of second embodiment of the invention;
Fig. 5 shows the running schematic diagram of the capacitance-type switch of Fig. 4;
Fig. 6 shows another block diagram of the capacitance-type switch of first embodiment of the invention, and it comprises delay amplifying unit;
Fig. 7 A shows another block diagram of the capacitance-type switch of second embodiment of the invention, and it comprises delay amplifying unit;
Fig. 7 B shows the running schematic diagram of the capacitance-type switch of Fig. 7 A;
Fig. 8 shows the block diagram of the capacitance-type switch of third embodiment of the invention, and it comprises a plurality of detecting units.
Description of reference numerals
1,2 capacitance-type switchs
11,21 drive circuits
131,131', 231,233 testing circuits
1311,1331,2311,2331 comparing units
1313,1333 postpone amplifying unit
133 reference circuits
15,251,253 judging units
17,27 control units
19 multiplexers
2315,2335 dividers
Sd drives signal
SI, SI1, SI2 judge signal
Sc control signal
S1 first signal
S2 secondary signal
Cd, Cd1, Cd2 Detection capacitance
Cref reference capacitance
Δ P phase difference
REd, REd' detection signal rising edge
REref, REref' reference signal rising edge.
Embodiment
The invention relates to a kind of capacitance-type switch, the capacitance variations producing in order to inspected object (such as human body) contact relatively output control signal are to control the operating parameters such as the keying (ON/OFF) of electronic installation, exert oneself (output), directivity (directivity); Wherein, described electronic installation there is no specific limited, can be the electronic installation that general household appliances or mobile electronic product etc. can be used switch to control.Capacitance-type switch of the present invention comprises at least one testing circuit and the reference circuit of duplicate circuit (replica) each other; Wherein, the Output rusults of described reference circuit, in order to compare with the testing result of described testing circuit, is eliminated the electrical skew that processing procedure and environmental factor cause, whereby to increase accuracy of detection.In the present invention's explanation, so-called duplicate circuit refers to circuit characteristic identical (for example having identical load), is preferably based on the made person of same process.
Shown in Fig. 1, it shows the block diagram of the capacitance-type switch 1 of first embodiment of the invention, and it comprises drive circuit 11, testing circuit 131, reference circuit 133 and judging unit 15; Wherein, described reference circuit 133 is the duplicate circuit of described testing circuit 131.
Described drive circuit 11 for example comprises oscillator or signal generating circuit, in order to output drive signal Sd periodically; Wherein, described driving signal Sd such as can be driving signal that square wave, string ripple, trapezoidal wave, triangular wave etc. can be picked out high voltage level H and low-voltage level L all can, there is no specific limited.In addition, the fixed cycle is not exported described driving signal Sd to described drive circuit 11 yet.In the present embodiment, described drive circuit 11 is inputted and is had identical characteristics simultaneously, such as the driving signal Sd with same intensity, waveform and phase place etc. to described testing circuit 131 and described reference circuit 133.For example that described testing circuit 131 receives simultaneously and drives signal Sd with described reference circuit 133, or by described drive circuit 11 produce two groups of homophases driving signal Sd offer respectively described testing circuit 131 and described reference circuit 133.In other embodiment, described drive circuit 11 also can provide respectively that tool preset phase is poor but waveform is identical two drives signals to described testing circuit 131 and described reference circuit 133.
Described testing circuit 131 inclusion test capacitor C d, described driving signal Sd is in order to charge to produce first signal S1 or secondary signal S2 to described Detection capacitance Cd; Wherein, described Detection capacitance Cd can be Single Capacitance or a plurality of electric capacity is formed by connecting.In more detail, described testing circuit 131, in order to detect contact according to the capacitance variations of described Detection capacitance Cd, is not exported described first signal S1 and according to described driving signal Sd, export described secondary signal S2 when described contact being detected according to described driving signal Sd when described contact being detected; Wherein, described first signal S1 and described secondary signal S2 are the signal that described driving signal Sd produces described Detection capacitance Cd charging.When coming in contact, the capacitance of described Detection capacitance Cd changes and makes the charging curve of described Detection capacitance Cd change simultaneously and cause phase delay; Also, described secondary signal S2 can postpone described first signal S1 phase difference; Wherein, the phase place extent causing because of contact is to determine according to circuit parameter.
Described reference circuit 133 comprises reference capacitance Cref, and the value of wherein said reference capacitance Cref can be identical with described Detection capacitance Cd or not identical, and in embodiments of the present invention, the capacitance of described reference capacitance Cref is identical with described Detection capacitance Cd.In the present invention, because described reference circuit 133 is not in order to detect contact event, therefore described driving signal Sd only produces described first signal S1 after described reference capacitance Cref is charged and can not produce described secondary signal S2.In more detail, described reference circuit 133 is in order to export all the time described first signal S1 according to described driving signal Sd to the charging of described reference capacitance Cref, and it is same as the described first signal S1 that described testing circuit 131 is exported.Because the function of described reference circuit 133 is in order to compare with described testing circuit 131, so the present invention mainly carries out contact detection according to the capacitance variations of described testing circuit 131, and described reference circuit 133 can be arranged in wafer.
Described judging unit 15 couples described testing circuit 131 and described reference circuit 133, in order to the phase difference output judgement signal SI(according to the described first signal S1 of the described secondary signal S2 of described testing circuit 131 and described reference circuit 133, is below illustrating for example).
Fig. 2 A shows the operation chart of the capacitance-type switch of Fig. 1.Referring to Fig. 1 and Fig. 2 A, described drive circuit 11 is output drive signal Sd periodically; Wherein, for convenience of description, described driving signal Sd is shown as square wave (square wave) herein, but described driving signal Sd is not limited to square wave as previously mentioned.When contact not detected, described testing circuit 131 is according to described driving signal Sd output first signal S1; When contact being detected, described testing circuit 131 is according to described driving signal Sd output secondary signal S2; Wherein, described secondary signal S2 postpones described first signal S1 phase difference P(as the signal on node A).Described reference circuit 131 is exported described first signal S1(as the signal in Node B according to described driving signal Sd all the time).
For example, the described first signal S1 of described testing circuit 131 outputs has detection signal rising edge REd and described secondary signal S2 has detection signal rising edge REd'; The described first signal S1 of described reference circuit 133 outputs has reference signal rising edge REref.In one embodiment, when described testing circuit 131 does not detect contact, described detection signal rising edge REd and described reference signal rising edge REref do not have phase difference; When described testing circuit 131 detects contact, described detection signal rising edge REd' and described reference signal rising edge REref produce phase difference P.Should be noted that, according to the difference of described driving signal Sd, described detection signal rising edge and described reference signal rising edge also can be replaced with detection signal trailing edge and reference signal trailing edge respectively.In more detail, testing circuit described in the present embodiment 131 can be exported reference signal rising edge or trailing edge (rise/fall edge) with capacitance variations (causing because contacting) according to described driving signal Sd in different time output detection signal rising edge or the described reference circuit 133 of trailing edge (rise/fall edge) according to described driving signal Sd.The phase difference P of 15 described detection signal rising edges of judgement of described judging unit and described reference signal rising edge or described detection signal trailing edge and described reference signal trailing edge is with output judgement signal SI.In addition, please refer to shown in Fig. 2 B and Fig. 2 C, when described testing circuit 131 does not detect contact, described first signal S1 in described node A and described Node B can have a little phase difference, and the example as shown in Figure 2 B slightly leading described reference signal rising edge REref of described detection signal rising edge Red and Fig. 2 C shows that described detection signal rising edge Red slightly falls behind described reference signal rising edge REref.When described testing circuit 131 detects contact, described detection signal rising edge REd' and described reference signal rising edge REref produce obvious phase difference P, 15 generations that can judge accordingly contact event of described judging unit.
Capacitance-type switch 1 of the present invention can also comprise control unit 17 according to described judgement signal SI output control signal Sc, for example according to described phase difference P and the comparative result of threshold value export described control signal Sc to electronic installation to carry out corresponding control; Wherein, described threshold value can determine according to required detection sensitivity.
In one embodiment, described drive circuit 11 can arrange respectively and be electrically connected to each other with described control unit 17.In another embodiment, described drive circuit 11 can be incorporated in described control unit 17, so 17 functions of carrying out described drive circuits 11 of described control unit, for example export described driving signal Sd so that Detection capacitance and reference capacitance are charged, and export described control signal Sc according to described judgement signal SI.
Described judging unit 15 is according to different execution modes, exportable different judgement signal SI.In the present embodiment, described judging unit 15 for example can comprise to judge time-to-digit converter (the Time to Digital Converter of described phase difference P, TDC), phase detectors (Phase Detector, PD), d type flip flop (D Flip Flop, DFF) or AND gate (AND gate).
Shown in Fig. 2 A, when described judging unit 15 comprises described time-to-digit converter (TDC), described judging unit 15 can be usingd as described judgement signal SI containing the numerical data D of described phase difference P information according to described phase difference P output packet, and described numerical data D is such as can be the data such as 2 bits, 4 bits, there is no specific limited.If described judging unit 15 comprises or do not comprise described phase detectors (PD) or described d type flip flop (DFF), when 15 judgements of described judging unit exist phase difference P, change signal level (for example can become L or become H from L from H) and using and when described judging unit 15 judges, maintain signal level as described judgement signal SI while there is not phase difference P.When described judging unit 15 comprises described AND gate (AND), described judging unit 15 can for example be usingd, as described judgement signal SI, illustrated T1 and T2 according to the signal of the poor Δ P output unlike signal width of out of phase (duration).Should be noted that, in Fig. 2 A, sequential to each other of each signal is closed and is not limited to shown in figure, and it is only in order to illustrate that described judging unit 15 can export different judgement signal SI according to different execution modes, not in order to limit the present invention.
Please refer to shown in Fig. 3, it shows another block diagram of the capacitance-type switch 1 of the embodiment of the present invention.As previously mentioned, because described driving signal Sd there is no specific limited, described testing circuit 131 and described reference circuit 133 can also comprise respectively comparing unit 1311 and 1333 in order to described first signal S1 and described secondary signal S2 are converted to square-wave signal (as shown in Figure 2 A), so that the phase difference P between described detection signal rise/fall edge and described reference signal rise/fall edge is easy to judgement; Wherein, described comparing unit 1311 and 1333 for example can be slicer (slicer), reverser (inverter) or buffer (buffer).In addition, the running of other elements is same as Fig. 1, therefore repeat no more in this.
Please refer to shown in Fig. 4, it shows the block diagram of the capacitance-type switch 2 of second embodiment of the invention, and it comprises the first testing circuit 231, the second testing circuit 233, the first judging unit 251, the second judging unit 253 and control unit 27; Wherein, described control unit 27 comprises drive circuit 21, and drive circuit 21 described in other embodiment also can not be arranged in described control unit 27 (as shown in Figure 1).In the present embodiment, described the first testing circuit 231 demonstrations comprise the first Detection capacitance Cd1 and the first comparing unit 2311; Described the second testing circuit 233 demonstrations comprise the second Detection capacitance Cd2 and the second comparing unit 2331, and as previously mentioned, described the first comparing unit 2311 and described the second comparing unit 2331 can be implemented.The difference of the second embodiment and the first embodiment is, in the second embodiment, two Detection capacitance Cd1 all can contact in order to detect with Cd2; In more detail, when described in object contact during the first testing circuit 231,233 reference circuits that are used as described the first testing circuit 231 of described the second testing circuit, vice versa.Therefore, the first testing circuit 231 described in the second embodiment and described the second testing circuit 233 duplicate circuit each other.As previously mentioned, described judging unit 251 and 253 can comprise time-to-digit converter (TDC), phase detectors (PD), d type flip flop (DFF) or and lock (AND).In addition, described capacitance-type switch 2 also can comprise wherein one of input that the first inverter 271 and the second inverter 273 be coupled to judging unit 251 and 253, usings as phase delay element; Said node P1 and P2 power on signal can be had a small phase difference, avoid the situation that cannot differentiate.Scrutable, described phase delay element nonessential use inverter.
Fig. 5 shows the running schematic diagram of the capacitance-type switch 2 of Fig. 4.Referring to Fig. 4 and Fig. 5, described control unit 27(or described driver element 21) export identical driving signal Sd to described the first testing circuit 231 and described the second testing circuit 233.Described the first testing circuit 231 and described the second testing circuit 233 be respectively in order to detect and to contact according to the capacitance variations of described the first Detection capacitance Cd1 and described the second Detection capacitance Cd2, for example, in figure, show respectively described the first Detection capacitance Cd1 and described the second Detection capacitance Cd2 changes because object contact makes capacitance.In the present embodiment, when detecting while contacting according to described driving signal Sd output first signal S1 and when described the first testing circuit 231 and described the second testing circuit 233 detect while contacting, described the first testing circuit 231 and described the second testing circuit 233 do not export secondary signal S2(as the signal on node P1 and node P2 according to described driving signal).Described the first judging unit 251 judges signal SI1 in order to the first phase difference P1 output first according to the described first signal S1 of the described secondary signal S2 of described the first testing circuit 231 and described the second testing circuit 233.Described the second judging unit 253 judges signal SI2 in order to the second phase difference P2 output second according to the described first signal S1 of the described secondary signal S2 of described the second testing circuit 233 and described the first testing circuit 231.As previously mentioned, described the first phase difference P1 and described the second phase difference P2 can be detection signal rising edge between phase difference or the phase difference between detection signal trailing edge.
As previously mentioned, according to different execution modes, described the first judging unit 251 and described the second judging unit 253 can comprise respectively time-to-digit converter, phase detectors, d type flip flop or AND gate, to export different judgement signal SI1, SI2(as shown in Figure 2 A).
As previously mentioned, described the first comparing unit 2311 and described the second comparing unit 2333 are in order to described first signal S1 and described secondary signal S2 are converted to square-wave signal, so that phase difference P1 and Δ P2 between described detection signal rise/fall edge and described reference signal rise/fall edge are easy to judgement; Wherein, described comparing unit 2311 and 2333 for example can be slicer, reverser or buffer equally.
27 of described control units carry out corresponding control according to described the first judgement signal SI1 or described the second judgement signal SI2 output control signal Sc to electronic installation.Scrutablely be, due to described the first testing circuit 231 and described the second testing circuit 233 be each other reference circuit each other in order to increase accuracy of detection, therefore preferably described the first testing circuit 231 with described the second testing circuit 233 in order to detect and not contact simultaneously; For example, in an embodiment, when 27 of control units described in described the first testing circuit 231 and described the second testing circuit 233 detect while contacting do not send described control signal Sc simultaneously.
Please refer to shown in Fig. 6, it shows another block diagram of the capacitance-type switch 1 of the embodiment of the present invention.In order to increase judgement sensitivity, in the present invention, also can delay amplifying circuit 1313 and 1333 be set respectively in order to amplify the phase difference P of the described secondary signal S2 of described testing circuit 131 and the described first signal S1 of described reference circuit 133 in described testing circuit 131 and described reference circuit 133.The operation of other element is same as Fig. 1, therefore repeat no more in this.Should be noted that, though Fig. 6 with the first embodiment, illustrate, postpone amplifying circuit and also can be applicable to the second embodiment of the present invention.
For example, with reference to shown in Fig. 7 A, it shows that the first testing circuit 231 described in second embodiment of the invention and described the second testing circuit 233 comprise respectively delay amplifying circuit, in order to amplify respectively described the first phase difference P1 and described the second phase difference P2.In the present embodiment, described delay amplifying circuit is in order to feed back to described drive circuit 21 by described first signal S1 and the described secondary signal S2 of described the first testing circuit 231 and described the second testing circuit 233 outputs.Described the first testing circuit 231 and described the second testing circuit 233 for example comprise delay line, by first signal S1 and secondary signal S2 are fed back to repeat to amplify described the first phase difference P1 and described the second phase difference P2 through delay line.
Shown in Fig. 7 B, it shows the running schematic diagram of the capacitance-type switch 2 of Fig. 7 A.When described the first detecting unit 231 and described the second detecting unit 233 be not during all by object contact (contactless), the signal of node P3 and P4 is for example cycles 20 microsecond (deration of signal is 10 microseconds); When described the first detecting unit 231 is during by object contact (having contact), because of the variation of capacitance, the signal period of node P3 is for example changed to 20.4 microseconds (deration of signal is 10.2 microseconds) and the signal period of node P4 is still maintained 20 microseconds (deration of signal is 10 microseconds).Therefore, described the first judging unit 251 can judge signal SI1 according to the output signal of described the first testing circuit 231 (node P3) and the phase difference P output first of the output signal (node P4) of described the second testing circuit 233 equally.As previously mentioned, when described phase difference P is greater than threshold value, described the first judging unit 251 is just judged the event that comes in contact.
In another embodiment, for making the phase difference on described the first detecting unit 231 and described second detecting unit 233 each detection signal rise/fall edges of exporting more obvious, described first signal S1 and described secondary signal S2 that the delay amplifying circuit of described the first detecting unit 231 and described the second detecting unit 233 can also comprise respectively after divider 2315 and 2335 pairs of feedbacks carry out division arithmetic.For example, referring again to shown in Fig. 7 B, it shows that the divisor (divisor) of described divider 2315 and 2335 is the running of 4 o'clock.For example, when described the first detecting unit 231 and described the second detecting unit 233 be not during all by object contact (contactless), between the fall/rising edge of detection signal that the above divider 2315 and 2335 of node P3 and P4 is exported, there is no phase difference; When described the first detecting unit 231 is during by object contact (having contact), between the fall/rising edge of detection signal that the above divider 2315 and 2335 of node P3 and P4 is exported, there is phase difference P.Described the first judging unit 251 equally can be according to described phase difference P output the first judgement signal SI1 between the output signal of the output signal of described the first testing circuit 231 and described the second testing circuit 233.
Should be noted that, if the second detecting unit 233 described in Fig. 7 A does not contact in order to inspected object, the function of described the second detecting unit 233 can be implemented with 253 of identical and described the second judging units of described reference circuit 133 of Fig. 1.In other words, delay amplifying circuit shown in Fig. 7 A can be used for Fig. 1 equally, in order to the described first signal S1 of described testing circuit 131 outputs and described secondary signal S2 are fed back to described drive circuit 11 and the described first signal S1 of described reference circuit 133 outputs is fed back to described drive circuit 11.Described delay amplifying circuit can comprise equally described first signal S1 after divider is fed described testing circuit 231 and described secondary signal S2 carry out division arithmetic and described reference circuit 233 is fed after described first signal S1 carry out division arithmetic.
In addition, Capacity control switch 1 of the present invention can arrange one group of reference circuit and organize testing circuit to be applied to a plurality of switches more.For example, with reference to shown in Fig. 8, it shows the block diagram of the capacitance-type switch 3 of third embodiment of the invention, its comprise each other for a plurality of testing circuits 131,131 of duplicate circuit ' ... with reference circuit 133; Wherein, each testing circuit 131,131 ' ... with described reference circuit 133 can according to the 1st, 3 and 6-7 figure implement.Described testing circuit 131,131 ' ... for example can be coupled to described judging unit 15 via multiplexer 19.Whereby, described judging unit 15 can sequentially compare each testing circuit 131,131 ' ... described secondary signal S2 and the phase difference of the described first signal S1 of described reference circuit 133 with output judgement signal (as Fig. 2 A).In other words, can to comprise be at least one testing circuit and the reference circuit of duplicate circuit to the capacitance-type switch of the embodiment of the present invention each other; Wherein, described drive circuit 11 output drive signal Sd and described judging unit 15 each testing circuit 131,131 of judgement ' ... and the mode of the phase difference between the output signal of described reference circuit 133 is similar to the first embodiment, therefore repeat no more in this.
In sum, known capacitance testing circuit has and changes the not good problem of accuracy of detection that causes because of circuit characteristic.Therefore, the present invention separately provides a kind of capacitance-type switch (Fig. 1, Fig. 3, Fig. 4, Fig. 6, Fig. 7 A and Fig. 8), it forms two is the testing circuit of duplicate circuit each other, and when utilizing one of them testing circuit to carry out contact detection, another testing circuit is used as reference circuit.Because two testing circuits are identical, when circuit for generating characteristic changing, also can produce identical variation, eliminate whereby the erroneous judgement situation causing because of circuit characteristic change.
Although the present invention discloses by previous examples, it is not in order to limit the present invention, any technical staff in the technical field of the invention with common knowledge, without departing from the spirit and scope of the present invention, when doing various changes and modification.Therefore the scope that protection scope of the present invention ought define depending on accompanying claim is as the criterion.
Claims (20)
1. a capacitance-type switch, this capacitance-type switch comprises:
Drive circuit, this drive circuit is in order to output drive signal;
At least one testing circuit, this at least one testing circuit, in order to detect contact according to capacitance variations, is not exported first signal and according to described driving signal, export secondary signal when described contact being detected according to described driving signal when described contact being detected;
Reference circuit, this reference circuit is in order to export described first signal according to described driving signal, the duplicate circuit that wherein said reference circuit is described testing circuit; And
Judging unit, judges signal in order to the phase difference output according to the described first signal of the described secondary signal of described testing circuit and described reference circuit.
2. capacitance-type switch according to claim 1, wherein said judging unit comprises time-to-digit converter, phase detectors, d type flip flop or AND gate.
3. capacitance-type switch according to claim 1, wherein said testing circuit and described reference circuit comprise delay amplifying circuit, and this delay amplifying circuit is in order to amplify described phase difference.
4. capacitance-type switch according to claim 3, wherein said delay amplifying circuit is in order to feed back to described drive circuit by described first signal and the described secondary signal of described testing circuit output.
5. capacitance-type switch according to claim 4, wherein said delay amplifying circuit comprises divider, and described first signal and the described secondary signal of this divider after to feedback carried out division arithmetic.
6. capacitance-type switch according to claim 1, wherein said testing circuit and described reference circuit comprise comparing unit, and this comparing unit is in order to be converted to square-wave signal by described first signal and described secondary signal.
7. capacitance-type switch according to claim 6, wherein said comparing unit is slicer, reverser or buffer.
8. capacitance-type switch according to claim 1, wherein, when described capacitance-type switch comprises a plurality of testing circuit, also comprises multiplexer, and this multiplexer is connected between described testing circuit and described judging unit.
9. capacitance-type switch according to claim 1, this capacitance-type switch also comprises control unit, and this control unit is in order to according to described judgement signal output control signal.
10. a capacitance-type switch, this capacitance-type switch comprises:
Drive circuit, this drive circuit is in order to output drive signal;
The first testing circuit and the second testing circuit, duplicate circuit each other, this first testing circuit, is not exported first signal and according to described driving signal, export secondary signal when described contact being detected according to described driving signal when described contact being detected in order to detect and to contact according to capacitance variations with the second testing circuit;
The first judging unit, this first judging unit is in order to judge signal according to the first-phase potential difference output first between the described secondary signal of described the first testing circuit and the described first signal of described the second testing circuit; And
The second judging unit, this second judging unit is in order to judge signal according to the second-phase potential difference output second between the described secondary signal of described the second testing circuit and the described first signal of described the first testing circuit.
11. capacitance-type switchs according to claim 10, wherein said the first judging unit and described the second judging unit comprise time-to-digit converter, phase detectors, d type flip flop or AND gate.
12. capacitance-type switchs according to claim 10, wherein said the first testing circuit and described the second testing circuit comprise delay amplifying circuit, and the delay amplifying circuit of described the first testing circuit and described the second testing circuit is respectively in order to amplify described first-phase potential difference and described second-phase potential difference.
13. capacitance-type switchs according to claim 12, wherein said delay amplifying circuit is in order to feed back to described drive circuit by described first signal and the described secondary signal of described the first testing circuit and described the second testing circuit output.
14. capacitance-type switchs according to claim 13, wherein said delay amplifying circuit comprises divider, and this divider carries out division arithmetic to described first signal and described secondary signal after feeding back.
15. capacitance-type switchs according to claim 10, wherein said the first testing circuit and described the second testing circuit comprise comparing unit, and this comparing unit is in order to be converted to square-wave signal by described first signal and described secondary signal.
16. capacitance-type switchs according to claim 15, wherein said comparing unit is slicer, reverser or buffer.
17. capacitance-type switchs according to claim 10, this capacitance-type switch also comprises control unit, and this control unit is in order to export control signal according to described the first judgement signal or described the second judgement signal.
18. 1 kinds of capacitance-type switchs, this capacitance-type switch comprises:
Control unit, this control unit is in order to output drive signal;
At least one testing circuit, this at least one testing circuit is in order to detect contact according to capacitance variations, and according to described driving signal and described capacitance variations at different time output detection signal rising edge or trailing edge;
Reference circuit, this reference circuit is in order to export reference signal rising edge or trailing edge, the duplicate circuit that wherein said reference circuit is described testing circuit according to described driving signal; And
Judging unit, this judging unit judges the phase difference of described detection signal rising edge and described reference signal rising edge or described detection signal trailing edge and described reference signal trailing edge;
Wherein, described control unit is also according to the comparative result output control signal of described phase difference and threshold value.
19. capacitance-type switchs according to claim 18, wherein said judging unit comprises to judge time-to-digit converter, phase detectors, d type flip flop or the AND gate of described phase difference.
20. capacitance-type switchs according to claim 18, wherein said testing circuit and described reference circuit comprise respectively to export slicer, reverser or the buffer of described detection signal rising edge or trailing edge and described reference signal rising edge or trailing edge.
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| CN201310148319.4A CN104124953A (en) | 2013-04-25 | 2013-04-25 | High-precision capacitive switch |
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| CN201310148319.4A CN104124953A (en) | 2013-04-25 | 2013-04-25 | High-precision capacitive switch |
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| CN108536092A (en) * | 2018-06-30 | 2018-09-14 | 卡川尔流体科技(上海)有限公司 | A kind of novel intelligent start/stop structure |
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