CN2406254Y - Stray immunity industrial capacitance sensor adopting four-phase detection technology - Google Patents
Stray immunity industrial capacitance sensor adopting four-phase detection technology Download PDFInfo
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- CN2406254Y CN2406254Y CN 99238056 CN99238056U CN2406254Y CN 2406254 Y CN2406254 Y CN 2406254Y CN 99238056 CN99238056 CN 99238056 CN 99238056 U CN99238056 U CN 99238056U CN 2406254 Y CN2406254 Y CN 2406254Y
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- 238000001514 detection method Methods 0.000 title claims abstract description 6
- 230000036039 immunity Effects 0.000 title claims abstract description 5
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 239000013078 crystal Substances 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 claims description 4
- 239000013256 coordination polymer Substances 0.000 claims description 4
- 230000002457 bidirectional effect Effects 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 210000001367 artery Anatomy 0.000 claims 1
- 210000003462 vein Anatomy 0.000 claims 1
- 230000035945 sensitivity Effects 0.000 abstract 1
- 238000005259 measurement Methods 0.000 description 4
- 230000036737 immune function Effects 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 2
- 238000007792 addition Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
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Abstract
The utility model belongs to an industrial capacitance sensor. The circuit mainly comprises a pulse generating circuit, a ten-frequency dividing circuit, a four-frequency dividing circuit, a switching circuit, a current-voltage converting circuit, a differential amplifying circuit, a compensating and circuit gain adjusting circuit and a voltage-current converting circuit. Its key lies in, the utility model discloses a circuit adopts four-phase detection technique, and the advantage is simple structure, with low costs, has stray immunity function, can accurate discernment arrive 1 PF's electric capacity for a short time, and resolution ratio reaches nearly 0.001PF, and sensitivity is high.
Description
The utility model belongs to a kind of industrial capacitive transducer.
Capacitive transducer is widely used in industry and laboratory, and under many occasions, the electric capacity of measurand is very little, and is little of several PF or littler, and stray capacitance is very big, and for example: the electric capacity of one meter long shielded cable just has 100PF.Capacitive transducer does not in the market have spuious immunologic function, that is to say, testing result is subjected to the influence of stray capacitance.
The purpose of this utility model is: in order to address the above problem, provide the industrial capacitive transducer based on four phase detection techniques, this capacitive transducer has spuious immunologic function, can accurately discern little electric capacity to 1PF, and resolution reaches 0.001PF.
Industrial capacitive transducer of the present utility model is by pulse-generating circuit (1) (crystal oscillator X, hex inverter U
1), frequency circuit (2) (frequency division U very
2, switch s), divide by four circuit (3) (double D trigger), on-off circuit (4) (four bidirectional analog switch U
4, measured capacitance C
x), electric current---voltage conversion circuit (5) (amplifier 1, amplifier 2, resistance R
1, R
2, capacitor C
1--C
4), differential amplifier circuit (6) (amplifier 3, resistance R
3--R
6), compensation and circuit gain adjusting circuit (7) (amplifier 4, resistance R
8-R
10, variable resistor W
1, W
2), voltage-current converter circuit (8) (amplifier U
6, triode T
1, resistance R
11-R
16, variable resistor W
3And diode VD
1, VD
2) form.Line connection of the present utility model is: the hex inverter U in the pulse-generating circuit (1)
1Three not gates be connected in series the output termination crystal oscillator X of its input end and another not gate from beginning to end; The pulse that pulse-generating circuit (1) produces is by hex inverter U
1Be connected to the very middle frequency divider U of frequency circuit (2)
2Clock pulse input terminal CP and switch s, frequency divider U
2Enable control end CPE and reset terminal R ground connection, carry output terminal CO connects the other end of conversion switch s; Double D trigger U in the output termination divide by four circuit (3) of switch s
3A and U
3The clock pulse input terminal CP of B, d type flip flop U
3Signal input part D connect the output terminal of another d type flip flop respectively, reset terminal R and set end s ground connection, the pulse V of output terminal Q and Q output
01-V
04Deliver to on-off circuit (4) U
4Control end; The measured capacitance of flowing through C
xElectric current respectively through the sW of on-off circuit (4)
3And sW
4Connect the inverting input of middle amplifier 1 of electric current-voltage conversion circuit (5) and amplifier 2, in-phase input end ground connection; The output voltage of amplifier 1 and amplifier 2 is respectively through resistance R
3, R
4Deliver to the anti-phase and in-phase input end of the amplifier 3 in the differential amplifier circuit (6); The output circuit of amplifier 3 is through resistance R
7Deliver to the inverting input of amplifier 4 in compensation and the circuit gain circuitry (7).Compensate for regulator circuit connects+15V and-15V between, its output terminal is through resistance R
10Also connect the inverting input of amplifier 4; The output voltage of amplifier 4 is through resistance R
11Connect voltage--U in the current converter circuit (8)
6Inverting input, U
6Output signal through resistance R
14Deliver to triode T
1Base stage, output current is from T
1Emitter through resistance R
6Output.
Principle of work of the present utility model is:
Fig. 1 is industrial electric capacity principle of sensors figure.Crystal oscillator (4096) produces the 4MHz pulse.Pulse signal is directly delivered to or is passed through ten minutes frequency device (4017) and delivers to four frequency dividers (2 * 4013).This circuit can be selected 1MHz or two kinds of different frequencies of 100MHz.As required, also can increase some very frequency circuits again,, enlarge sensing range to obtain more kinds of frequencies.
Four-divider produces the square-wave signal of four dutycycles 50%, and phase place is respectively 0 ° 90 °, 180 ° and 270 °, as V among Fig. 2
01, V
02, V
03And V
04Shown in.These signals are used for controlling four phase detection line work.
Detect the unknown capacitance C of measurand
x, two square-wave signals--V
01And V
02Add to two CMOs switch sW1 and sW2, so that C
xLeft end or be connected to+15V, perhaps be connected to ground, the 15V square wave passes through C effectively
xForm electric current.All the other two ripple signal (V
03And V
04) be used for controlling other two CMOs switch: sW4 and sW3.The C that forms by square wave
xOn electric charge be discharged into through SW3 and put 1 or be discharged into amplifier 2 through sW4.In theory, electric charge is directly proportional with the capacity of the unknown capacitance of square wave amplitude (15V) and measurement.Amplifier 1 or amplifier 2 all convert charge current to voltage.The voltage swing of two amplifier outputs equates, opposite in sign.Capacitor C among the figure
1And C
2(0.1 μ) is used for absorbing spike, resistance R
1, R
2(10K) and capacitor C
3, C
4(4700PF) backfeed loop of formation amplifier.Amplifier 3 is differential amplifiers, from two d. c. voltage signals of amplifier 1 and amplifier 2 by amplifier 3 additions.Amplifier 4 is used for regulating the gain of compensation and circuit.Resultant voltage is from amplifier 4 outputs.
Stray capacitance is the electric capacity between capacitance electrode and the ground.There are two stray capacitances to be attached to C
xOn, an end of electric capacity is ground.The stray capacitance of left end is produced by power supply, and its output impedance can be ignored, and it does not influence the measurement of electric capacity.The stray capacitance of right-hand member always keeps being connected on the virtual earth via amplifier 1 or amplifier 2, and the current potential above it is zero, and therefore, this stray capacitance does not influence the measurement of electric capacity yet.Thus, this capacitance measurement circuit is spuious immunity.
When industrial application, carry signal often will use electric current, rather than voltage, at this moment just need a voltage---current converter.Be transformed into the electric current of the 4--20mA that meets industrial standard from the voltage signal of amplifier 4, so just become industrial capacitive transducer.
The utility model has the advantages that: simple in structure, cost is low, has spuious immunologic function, can accurately discern little electric capacity to 1PF, resolution reaches 0.001PF, and is highly sensitive.
Description of drawings
Fig. 1: the electrical schematic diagram of industrial capacitive transducer of the present utility model
Fig. 2: double D trigger output waveform figure
1. 2. ten fens frequency circuit 3. divide by four circuits of pulse-generating circuit, 4. on-off circuits
5. electric current--voltage conversion circuit 6. differential amplifier circuits 7. compensation and circuit gain circuitry 8. voltages--each device parameter values in the current converter circuit circuit: X:4MHz crystal oscillator U
1: hex inverter CD4069 U
2: decimal system counting/frequency division CD4017 U
3: double D trigger CD4013 U
4: four bidirectional analog switch CD4017 U
5, U
6: four high guaily unit device LM324 S: toggle switch R
1--7: 10KR
8, R
9: 5.1K R
10--1510k; R
16: 250 Ω C
1, C
2: 0.1 μ C
3, C
4: 4700PF C
5, C
60.1 μ W
1: 1K W
2: 51K W
3: 600 Ω VD
1, VD
2: 1N4148 T
1: DA150
Claims (1)
1. adopt the industrial capacitive transducer of spuious immunity of four phase detection techniques, it is characterized in that: it is by pulse-generating circuit (1), ten minutes frequency circuit (2), divide by four circuit (3), on-off circuit (4), electric current--voltage conversion circuit (5), differential amplifier circuit (6), compensation and circuit gain adjusting circuit (7) and voltage-current converter circuit (8) formation, and the composition of each circuit and connected mode are:
A, pulse-generating circuit (1) are by crystal oscillator X, hex inverter U
1Form hex inverter U
1In three not gates be connected in series from beginning to end, its input end and another non-gate output terminal meet crystal oscillator X, signal is delivered to frequency divider U in the arteries and veins
2Clock pulse input terminal CP and switch s;
B, ten minutes frequency circuit (2) are by frequency divider U
2Form frequency divider U with switch s
2Enable control end CPE and reset terminal R ground connection, carry output terminal CO connects the other end that s day is closed in conversion; The output termination double D trigger U of s
3A and U
3The clock pulse input terminal CP of B;
C, divide by four circuit (3) are by two d type flip flop U
3A and U
3B forms, and the signal input part D of d type flip flop is connected to the output terminal Q and the Q of another d type flip flop respectively, reset terminal R and set end s ground connection, the pulse V of output terminal Q and Q output
01-V
04Deliver to on-off circuit U
4Control end;
D, on-off circuit (4) are by four bidirectional analog switch U
4, measured capacitance C
xForm the measured capacitance of flowing through C
xElectric current respectively through U
4Sw
3S and w
4With the inverting input that is connected to operational amplifier 1 and operational amplifier 2;
E, electric current--voltage conversion circuit (5) is by operational amplifier 1, operational amplifier 2, resistance R
1, R
2, capacitor C
1-C
4Form, the in-phase input end ground connection of amplifier 1 and amplifier 2, the output terminal of amplifier 1 and amplifier 2 is respectively through resistance R
3, R
4Differential discharge circuit in the anti-phase and in-phase input end of amplifier 3 link to each other;
F, differential amplifier circuit (6) are by amplifier 3, resistance R
3-R
6Form, the output terminal of amplifier 3 is through resistance R
7Link to each other with the inverting input of amplifier 4;
G, compensation and circuit gain adjusting circuit (7) are by amplifier 4, resistance R
8-R
10And variable resistor W
1, W
2Form, compensate for regulator circuit is connected to+15V and-15V between, its output terminal is through resistance R
10Connect the inverting input of amplifier 4, the output terminal of amplifier 4 meets amplifier U through resistance R 1
6Inverting input.
H. voltage--current converter circuit (8) is by operational amplifier U
6, triode T
1, resistance R
11-R
16, variable resistor W
3And diode VD
1, VD
zForm amplifier U
6In-phase input end pass through resistance R
12Ground connection, and pass through resistance R
15Connect current output terminal; U
6Output signal through resistance R
14To triode T
1Base stage, T
1Emitter through resistance R
16To current output terminal, and through resistance R
13With variable resistor W
3Feed back to U
6Inverting input; Current output terminal output 4--20mA electric current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 99238056 CN2406254Y (en) | 1999-07-07 | 1999-07-07 | Stray immunity industrial capacitance sensor adopting four-phase detection technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 99238056 CN2406254Y (en) | 1999-07-07 | 1999-07-07 | Stray immunity industrial capacitance sensor adopting four-phase detection technology |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2406254Y true CN2406254Y (en) | 2000-11-15 |
Family
ID=34025567
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 99238056 Expired - Fee Related CN2406254Y (en) | 1999-07-07 | 1999-07-07 | Stray immunity industrial capacitance sensor adopting four-phase detection technology |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2406254Y (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100350438C (en) * | 2001-02-07 | 2007-11-21 | 格伦雷茨家族信托公司 | Control system with capacitive detector |
| CN102981053A (en) * | 2012-11-20 | 2013-03-20 | 天津锐意泰克汽车电子有限公司 | Secondary resistance detection circuit of ignition coil |
| CN111585562A (en) * | 2020-04-29 | 2020-08-25 | 西安交通大学 | Capacitive touch sensing unit for nerve morphology output |
| CN111817697A (en) * | 2019-04-11 | 2020-10-23 | 深圳市飞翼科技有限公司 | Capacitive touch key environment compensation circuit and method |
-
1999
- 1999-07-07 CN CN 99238056 patent/CN2406254Y/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100350438C (en) * | 2001-02-07 | 2007-11-21 | 格伦雷茨家族信托公司 | Control system with capacitive detector |
| CN102981053A (en) * | 2012-11-20 | 2013-03-20 | 天津锐意泰克汽车电子有限公司 | Secondary resistance detection circuit of ignition coil |
| CN102981053B (en) * | 2012-11-20 | 2015-03-04 | 天津锐意泰克汽车电子有限公司 | Secondary resistance detection circuit of ignition coil |
| CN111817697A (en) * | 2019-04-11 | 2020-10-23 | 深圳市飞翼科技有限公司 | Capacitive touch key environment compensation circuit and method |
| CN111585562A (en) * | 2020-04-29 | 2020-08-25 | 西安交通大学 | Capacitive touch sensing unit for nerve morphology output |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |