CN109672452A - A kind of pressure sensitivity key detection differential circuit and electronic equipment - Google Patents
A kind of pressure sensitivity key detection differential circuit and electronic equipment Download PDFInfo
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- CN109672452A CN109672452A CN201910136562.1A CN201910136562A CN109672452A CN 109672452 A CN109672452 A CN 109672452A CN 201910136562 A CN201910136562 A CN 201910136562A CN 109672452 A CN109672452 A CN 109672452A
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- pressure sensitivity
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- 230000035945 sensitivity Effects 0.000 title claims abstract description 28
- 238000001514 detection method Methods 0.000 title claims abstract description 17
- 239000003990 capacitor Substances 0.000 claims abstract description 37
- 230000011664 signaling Effects 0.000 claims abstract description 13
- 239000011888 foil Substances 0.000 claims description 8
- 238000000034 method Methods 0.000 abstract description 3
- 230000005611 electricity Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M11/00—Coding in connection with keyboards or like devices, i.e. coding of the position of operated keys
- H03M11/02—Details
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- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The present invention provides a kind of pressure sensitivity push button signalling detection circuit, comprising: integrated operational amplifier；Pressure sensitivity bridge-type measuring circuit；The noninverting input of the first termination integrated operational amplifier of the pressure sensitivity bridge-type measuring circuit, the second end of the pressure sensitivity bridge-type measuring circuit connect the reverse input end of the integrated operational amplifier by first capacitor；Integrated operational amplifier first resistor in parallel between reverse input end and output end；Integrated operational amplifier second resistance in parallel between non-inverting input terminal and inverting input terminal.The present invention is by forward and reverse input terminal in amplifier, and the method for connecting resistance, allows differential capacitance or coupled capacitor to charge, improves starting up speed and stability.
Description
Technical field
The present invention relates to detection circuit fields, and in particular to a kind of detection circuit and electronic equipment of mobile phone pressure sensitivity key.
Background technique
Pressure sensitivity push button signalling detection circuit essence is exactly foil gauge measuring circuit, resistance of the foil gauge measuring circuit to foil gauge
Value parameter requires, it is desirable that the resistance value of 4 resistance of electric bridge is consistent, otherwise will lead to electric bridge imbalance, there is a fixed bias
Voltage output.This bias voltage is Offset.Pressure sensitivity key field is existing to be produced by the way of printing inductive reactance, due to
The precision of printing is difficult to control, and as the sensor of low cost, the Offset of this kind of sensor can be than MEMS and conventional foil gauge
The Offset of sensor is much larger, reaches 400-600mV.And the strain signal detected only has 1mV or so, if directly put
Greatly, it will lead to operational amplifier circuit saturation, to can't detect real strain signal.This is that measuring circuit is difficult to solve in current industry
Certainly the problem of.The producer of conventional production electric bridge foil gauge, produces the foil gauge of high-precision resistance value, needs with laser one by one
Amendment, it is at high cost.It is all to use mode of printing printed resistor inductor, the deviation of resistance value is just bigger in touch key-press field.
Have more chip companies DAC digital simulation converter output fixed-bias transistor circuits, to correct the deviation of electric bridge, then
Amplify 512 times again, may be implemented really.The problem is that having more a DAC structure complexity, cost is improved；DAC simultaneously
Interference can be brought, signal-to-noise ratio can reduce.The minimum signal that they can be detected at present is greater than noise, noise 20uV, Offset
Deviation is big, and noise also wants 3-4 times big.
The differential circuit ZL201620410244.1 proposed before applicant avoids the noise for introducing DAC, can detect
The signal of 1.5uV, but since differential capacitance charging process is slow causes to start the stable time very long.
Therefore, it is necessary to design a kind of new differential circuit.
Summary of the invention
The present invention is directed at least solve one of the technical problems existing in the prior art, a kind of new differential electricity is proposed
Road.
A kind of pressure sensitivity push button signalling detection circuit, comprising:
Integrated operational amplifier；
Pressure sensitivity bridge-type measuring circuit；The first of the pressure sensitivity bridge-type measuring circuit terminates the same of the integrated operational amplifier
To input terminal, the second end of the pressure sensitivity bridge-type measuring circuit connects the reversed of the integrated operational amplifier by first capacitor
Input terminal；
Integrated operational amplifier first resistor in parallel between reverse input end and output end；
Integrated operational amplifier second resistance in parallel between non-inverting input terminal and inverting input terminal.
It further, further include second be connected in parallel between the reverse input end and output end of the integrated operational amplifier
Capacitor.
It further, further include the low-pass filter for being connected to the output end of the integrated operational amplifier.
Further, the low-pass filter includes 3rd resistor and third capacitor, and wherein 3rd resistor is filter resistance,
Third capacitor is filter capacitor, and the first end of the 3rd resistor connects the output end of the integrated operational amplifier, second end
Connect the first end of the filter capacitor, the second end ground connection of the filter capacitor.
It further, further include the 4th capacitor, the 4th capacitor is decoupling capacitor, and the first end of the 4th capacitor connects
Connect input supply terminal, second end ground connection.
Further, the Standard resistance range of the second resistance is 1k-100k.
Further, the bridge-type measuring circuit includes that 4 foil gauges measure resistance.
The present invention also proposes a kind of electronic equipment, including pressure sensitivity push button signalling detection circuit proposed by the invention.
The present invention increases resistance between amplifier positive and negative terminal, and circuit fast and stable can be made to get off, will not influence amplification factor.
Detailed description of the invention
Fig. 1 is the signal deteching circuit schematic diagram of a wherein embodiment of the invention；
When Fig. 2 is the circuit stability work of a wherein embodiment of the invention, output waveform figure, it is normal that display presses signal；
Fig. 3 is the output waveform figure before the present invention wherein the signal deteching circuit parallel connection R5 of an embodiment, display booting
Stablizing the time is 19S；
Fig. 4 is the output waveform figure of the wherein signal deteching circuit parallel connection 100KR5 of an embodiment of the invention, display booting
Stablizing the time is 4.7S；
Fig. 5 is the output waveform figure of the wherein signal deteching circuit parallel connection 10KR5 of an embodiment of the invention, and display booting is steady
It fixes time as 1.3S；
Fig. 6 is the output waveform figure of the wherein signal deteching circuit parallel connection 1KR5 of an embodiment of the invention, and display booting is steady
It fixes time as 0.7S.
Specific embodiment
Below in conjunction with attached drawing, detailed description of the preferred embodiments.It should be understood that this place is retouched
The specific embodiment stated is merely to illustrate and explain the present invention, and is not intended to restrict the invention.
With reference to Fig. 1, the present invention proposes a kind of pressure sensitivity push button signalling detection differential circuit, including integrated operational amplifier U1A
(RH332 normal operation amplifier), R1-R4 are sensor resistance (500 to 100K), R5 (20K-1M), R6 (1M to 20M), R7
(10K to 100K) bypass resistance, C1 (0.1uF to 10uF), C2 (0.1uF to 100uF), C3 (10pF to 0.01uF) capacitor；
Wherein, R1-R4 constitutes pressure sensitivity bridge-type measuring circuit；U1A, C2, R6, C3 form differential amplifier circuit, and R7, C4 form low-pass filtering
Circuit, C1 are decoupling capacitor.
Wherein, C2 is first capacitor, and C3 is the second capacitor, and C4 is third capacitor, and C1 is the 4th capacitor；R6 is the first electricity
Resistance, R5 is second resistance, and R7 is 3rd resistor.
The noninverting input of the first end connection integrated operational amplifier U1A of the pressure sensitivity bridge-type measuring circuit of R1-R4, second
End passes through the reverse input end of capacitor C2 connection integrated operational amplifier U1A.
Operational amplifier U1A passes through in its negative input end and output end parallel resistance R6 and capacitor C3 and C2, R5, R6 group
At reversed differential amplifier circuit.C3 provides narrow-band compensation and avoids U1A self-excitation.
In the present invention, bridge-type measuring circuit, C2, operational amplifier U1A, resistance R6 constitute the basic structure of circuit, i.e.,
C1 C3 C4 R7 make circuit operation it is more stable, but it is not necessary to.R5 is emphasis of the invention, it can allow C2 quick
Charging, reaches steady-working state.After circuit stability, amplifier positive and negative terminal is that void is short, and voltage difference 0, R5 no longer works.?
When having signal, R5 is avoided that the overshoot of signal, avoids distorted signals.Due to being the sensor of printing, Offset is on the left side 400mV
The time is stablized in the right side, the charging that C2 needs to grow very much, can only be charged originally by R6 to C2.After increasing R5, the charging time is obtained substantially
The reduction of degree.The present invention is inexpensive sensor as us by resistance R5, solves charging time too long technology
Problem can just encounter such problems.This resistance is best solution.
Specifically, when just powering on, electric bridge has Offset voltage deviation, and C2 capacitor both end voltage is 0.By ideal amplifier,
In linearity of amplifier range, input with mutually and reverse side+- between voltage be equal.But amplifier input is the same as phase and reverse phase
End+- between be it is empty short, impedance is infinity, and C2 capacitor both end voltage cannot be mutated, amplifier input with mutually and reverse side+- it
Between voltage is practical is equal to Offset voltage, amplifier saturation output, amplifier gain is bigger, and feedback resistance is bigger, and feedback resistance mentions
For the feedback current of confession with regard to smaller, feedback current is longer to capacitor charging time.After feedback current is full of to capacitor C2,
Input with mutually and reverse side+- between voltage just it is equal.If increasing R5, voltage is added in capacitor by R5 by Offset voltage
On C2, R5 provides charging current, and the time for allowing C2 to be full of greatly reduces.After C2 is full of, input with mutually and reverse side+- between electricity
Pressure is just equal, and amplifier could steady operation.
When amplifier steady operation, inductor resistance variations generate small-signal, and what when test was given is a square wave, is had
R5 and no R5, output differential signal amplitude do not change.As shown in Fig. 2, i.e. steady operation when, resistance R5 no longer works.
The amplifier output gain calculation formula of circuit of the present invention:Wherein:
Uo is amplifier output voltage,
Ui is op-amp input voltage
It is the differential value of input voltage.
In order to verify technical effect of the invention, following test experiments are carried out:
Amplifier U1A is tested with the output waveform mutually between reverse phase before and after parallel resistance R5, when verifying circuit booting is stablized
Between.
For example, each device to circuit of the present invention carries out suitable value, before parallel resistance R5, output waveform is such as
Shown in Fig. 3, circuit, which is switched on, stablizes time about 19s.
The parallel connection R5 between the non-inverting input terminal and inverting input terminal of amplifier U1A, resistance value 100k, output waveform is as schemed
Shown in 4, the circuit booting stable time is about 4.7s.
Parallel connection R5, resistance value 10k, output waveform such as Fig. 5 between the non-inverting input terminal and inverting input terminal of amplifier U1A
Shown, the circuit booting stable time is about 1.3s.
Parallel connection R5, resistance value 1k, output waveform such as Fig. 6 between the non-inverting input terminal and inverting input terminal of amplifier U1A
Shown, the circuit booting stable time is about 0.7s.
As it can be seen that by, with the mutually parallel resistance R5 between reverse phase, selecting suitable R5 resistance value in amplifier U1A, can effectively contract
The time is stablized in the booting of short-press key circuit.
It is understood that the principle that embodiment of above is intended to be merely illustrative of the present and the exemplary implementation that uses
Mode, however the present invention is not limited thereto.For those skilled in the art, essence of the invention is not being departed from
In the case where mind and essence, various changes and modifications can be made therein, these variations and modifications are also considered as protection scope of the present invention.
Claims (8)
1. a kind of pressure sensitivity push button signalling detection circuit characterized by comprising
Integrated operational amplifier；
Pressure sensitivity bridge-type measuring circuit；The first of the pressure sensitivity bridge-type measuring circuit terminates the in the same direction defeated of the integrated operational amplifier
Enter end, the second end of the pressure sensitivity bridge-type measuring circuit connects the reversed input of the integrated operational amplifier by first capacitor
End；
Integrated operational amplifier first resistor in parallel between reverse input end and output end；
Integrated operational amplifier second resistance in parallel between non-inverting input terminal and inverting input terminal.
2. pressure sensitivity push button signalling detection circuit according to claim 1, it is characterised in that: further include being connected in parallel on described integrate
The second capacitor between the reverse input end and output end of operational amplifier.
3. pressure sensitivity push button signalling detection circuit according to claim 1 or 2, it is characterised in that: further include be connected to it is described
The low-pass filter of the output end of integrated operational amplifier.
4. pressure sensitivity push button signalling detection circuit according to claim 3, it is characterised in that: the low-pass filter includes the
Three resistance and third capacitor, wherein 3rd resistor be filter resistance, third capacitor be filter capacitor, the first of the 3rd resistor
The output end of the end connection integrated operational amplifier, second end connect the first end of the filter capacitor, the filter capacitor
Second end ground connection.
5. pressure sensitivity push button signalling detection circuit according to claim 1 or 2, it is characterised in that: further include the 4th capacitor, institute
Stating the 4th capacitor is decoupling capacitor, the first end connection input supply terminal of the 4th capacitor, second end ground connection.
6. pressure sensitivity push button signalling detection circuit according to claim 1, it is characterised in that: the resistance value model of the second resistance
It encloses for 1k-100k.
7. pressure sensitivity push button signalling detection circuit according to claim 1, it is characterised in that: the bridge-type measuring circuit includes
4 foil gauges measure resistance.
8. a kind of electronic equipment, including pressure sensitivity push button signalling detection circuit described in any one of claims 1-6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910136562.1A CN109672452A (en) | 2019-02-25 | 2019-02-25 | A kind of pressure sensitivity key detection differential circuit and electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910136562.1A CN109672452A (en) | 2019-02-25 | 2019-02-25 | A kind of pressure sensitivity key detection differential circuit and electronic equipment |
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| Publication Number | Publication Date |
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| CN109672452A true CN109672452A (en) | 2019-04-23 |
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|---|---|---|---|
| CN201910136562.1A Pending CN109672452A (en) | 2019-02-25 | 2019-02-25 | A kind of pressure sensitivity key detection differential circuit and electronic equipment |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005241305A (en) * | 2004-02-24 | 2005-09-08 | Matsushita Electric Works Ltd | Phase adjustment circuit of watthour meter |
| JP2009047587A (en) * | 2007-08-21 | 2009-03-05 | Yamatake Corp | Sensor signal amplifying device |
| CN201296264Y (en) * | 2008-08-19 | 2009-08-26 | 深圳市远望谷信息技术股份有限公司 | Wheel sensor signal receiving circuit with adjustable sensitivity |
| CN205647500U (en) * | 2016-05-09 | 2016-10-12 | 深圳瑞湖科技有限公司 | Pressure key signal detection circuitry |
| CN107560640A (en) * | 2017-09-21 | 2018-01-09 | 甘肃远效科技信息咨询有限公司 | Capacitance detecting device and system |
| CN209627352U (en) * | 2019-02-25 | 2019-11-12 | 深圳瑞湖科技有限公司 | A kind of pressure sensitivity push button signalling detection circuit and electronic equipment |
-
2019
- 2019-02-25 CN CN201910136562.1A patent/CN109672452A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005241305A (en) * | 2004-02-24 | 2005-09-08 | Matsushita Electric Works Ltd | Phase adjustment circuit of watthour meter |
| JP2009047587A (en) * | 2007-08-21 | 2009-03-05 | Yamatake Corp | Sensor signal amplifying device |
| CN201296264Y (en) * | 2008-08-19 | 2009-08-26 | 深圳市远望谷信息技术股份有限公司 | Wheel sensor signal receiving circuit with adjustable sensitivity |
| CN205647500U (en) * | 2016-05-09 | 2016-10-12 | 深圳瑞湖科技有限公司 | Pressure key signal detection circuitry |
| CN107560640A (en) * | 2017-09-21 | 2018-01-09 | 甘肃远效科技信息咨询有限公司 | Capacitance detecting device and system |
| CN209627352U (en) * | 2019-02-25 | 2019-11-12 | 深圳瑞湖科技有限公司 | A kind of pressure sensitivity push button signalling detection circuit and electronic equipment |
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