CN205620981U - High sensitivity electric capacity touch key - Google Patents
High sensitivity electric capacity touch key Download PDFInfo
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- CN205620981U CN205620981U CN201620320963.4U CN201620320963U CN205620981U CN 205620981 U CN205620981 U CN 205620981U CN 201620320963 U CN201620320963 U CN 201620320963U CN 205620981 U CN205620981 U CN 205620981U
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Abstract
The utility model provides a high sensitivity electric capacity touch key, include the generator and the rectifier circuit that link to each other with parallelly connected capacitive sensing and distributed capacitance electrical property, still include stabiliser, electrical unit and amplifier, adc, digital analog converter and wave filter, its characterized in that: establish through the stabiliser between generator and the electrical unit and be connected, all establish through the amplifier between rectifier circuit and adc and rectifier circuit and the digital analog converter and is connected, establish through the wave filter between adc and the digital analog converter simultaneously and be connected, by aforementioned structure, solved high sensitivity electric capacity touch key's technical problem, reached sensitivity height, reliability and shock resistance by force and reduction in production cost's good result.
Description
Technical field
This utility model relates to electronic technology field, espespecially provides a kind of high sensitivity capacitor touch button.
Background technology
The basic functional principle of capacitor touch button is that the change of the upper distribution capacity by detection capacitance touching control induced key determines whether that finger is pressed against on touch controlled key.If not soft-touch control, touch controlled key distribution capacity has a fixing capacitance, if we use finger contact switch, will increase the distribution capacity of touch controlled key.So, we measure the change of distribution capacity on touch controlled key, it is possible to detecting touch action.
The ultimate principle of capacitance touch induced key is: when human body (finger) contacting metal sensing chip when, owing to human body is equivalent to the electric capacity connecing the earth, therefore can form an electric capacity between sensing chip and the earth, faradism capacity generally has a few pF to tens pF.Utilize the principle that this is most basic, build interlock circuit in outside, it is possible to according to the change of this capacitance, detect whether human contact's metal sensing chip.But owing to there being the factor of the aspect such as safe and attractive in appearance in the application of most household appliances, metal sensing chip can be placed the insulated coverings such as one layer of glass, human body is coupled with metal sensing chip by covering, thus makes faradism capacity drop to a few pF.But, some application is owing to there being the parts such as nixie display and LED can not the most directly dispose printed circuit board (PCB) on circuit board, can not be connected on device housings by printed circuit board, utilizing spring to build capacitance inductor capacitive induction is a kind of sane replacement scheme for conventional mechanical switch.This kind of application includes the household electrical appliance such as cooking stove, washing machine, electric refrigerator, microwave oven.
At present, the capacitor touch button in household appliances is applied mainly to have three kinds of implementations:
The first, the square wave that one amplitude of applying and frequency are fixed on touch controlled key, obtain the distributed capacitance on touch controlled key by the average current of test square wave；
The second, builds a multi-resonant oscillating circuit so that the distribution capacity on touch controlled key is resonant capacitance, obtains the distributed capacitance on touch controlled key by the frequency of oscillation of test multi-resonant oscillating circuit；
The third, apply a step signal, the distributed capacitance obtaining on touch controlled key by measuring the rise or fall time of this signal on touch controlled key.
At present, existing capacitance type touch control keys detection technique exists a common problem is that the sensitivity to capacitance detecting is the highest, it is possible to the minimum change of the touch controlled key distribution capacity that stable detection arrives is substantially in the scope of several pF.Under the conditions of such (detection sensitivity), the structure of touch controlled key is just had bigger restriction, such as in the application of the household appliances such as electromagnetic oven and lampblack absorber, owing to there being the parts such as nixie display and LED can not the most directly dispose printed circuit board (PCB) on circuit board, printed circuit board can not be connected on device housings, in order to ensure there is sufficiently large capacitance variations when the finger of people touches, metal spring must be installed on pcb board, use the mode person's of there is also shortcomings of metal spring induction apparatus in actual applications, such as will fill a spring due to each button, and spring is relatively costly, installation and the welding of spring are the most complicated in process of production, cause production cost higher.Additionally product actually used during if subjected to big vibrations or impact, be also easy to, so that spring departs from its position installed, cause touch controllable function to lose efficacy.Owing to existing scheme is inadequate to the detection sensitivity of touch controlled key distribution capacity, when the bond number of the touch controlled key needed is more, mode with regard to relatively difficult employing matrix-scanning carries out key scan, or bigger restriction can be encountered in actual applications by reducing the measures such as the thickness of the covering sensitivity with guarantee touch controlled key distribution capacity detection when forming the touch controlled key array of matrix-scanning form.
Owing to existing scheme is not high enough to the detection sensitivity of touch controlled key distribution capacity, the application such as intelligent switch cannot be accomplished the function close to sensing of remote human body sensing.
Summary of the invention
For solving above-mentioned technical problem, main purpose of the present utility model is to provide a kind of high sensitivity capacitor touch button.
For reaching above-mentioned purpose, the technical scheme of this utility model application is: provide a kind of high sensitivity capacitor touch button, including the generator being electrical connected with inductance capacitance in parallel and distribution capacity and rectification circuit, also include manostat, power subsystem and amplifier, analog-digital converter, digital to analog converter and wave filter, wherein: set up by manostat between generator with power subsystem and be connected；All set up by amplifier between rectification circuit with analog-digital converter and rectification circuit with digital to analog converter and be connected, set up by wave filter between analog-digital converter with digital to analog converter simultaneously and be connected.
Preferred in the present embodiment, inductance capacitance is to sense the electric capacity that human finger touches, and distribution capacity is touch controlled key sensing chip electric capacity.
Preferred in the present embodiment, generator is high frequency constant current pulse generator, and including frequency divider, MUX and constant current switch, frequency divider is can prescaler.
Preferred in the present embodiment, amplifier is variable gain amplifier, including positive input terminal and negative input end and outfan.
Preferred in the present embodiment, wave filter is variable bandwidth low-pass ripple device, and including central processing unit, pre-storage, wherein: positive input terminal is connected with analog-digital converter, negative input end is connected with digital to analog converter.
Preferred in the present embodiment, analog-digital converter uses 16 analog-digital converters, and digital to analog converter uses 8 figure place weighted-voltage D/A converters.
Preferred in the present embodiment, rectification circuit is circuit of synchronous rectification.
Compared with prior art, it has the advantages that this utility model:
This utility model is by being greatly improved the detection sensitivity of capacitance type touch control keys, the frame for movement making touch controlled key significantly simplifies, overall electric property is greatly improved, the range of application making the touch controlled key of household electric appliances is significantly expanded, thus all kinds of manufacturers obtaining technique obtain huge economic benefit, specifically: by improving the sensitivity of touch controlled key capacitance detecting, make touch controlled key can save metal spring induction apparatus and become a kind of capacitor touch button being capable of every sky sensing, and matrix-scanning button can be easily carried out and every empty induced key, the hardware and the production cost that make touch controlled key are greatly reduced, the reliability of whole system and shock resistance vibrations are greatly improved.
Accompanying drawing explanation
Fig. 1 is the frame structure schematic diagram of this utility model embodiment.
Fig. 2 is the board structure of circuit schematic diagram of Fig. 1.
Detailed description of the invention
Of the present utility model embodiment is described below in detail, and the example of described embodiment is shown in the drawings, and the most same or similar label represents same or similar element or has the element of same or like function.The embodiment described below with reference to accompanying drawing is exemplary, is only used for explaining the technical solution of the utility model, and is not construed as restriction of the present utility model.
In description of the present utility model, term " interior ", " outward ", " longitudinally ", " laterally ", " on ", D score, " top ", the orientation of the instruction such as " end " or position relationship be based on orientation shown in the drawings or position relationship, it is for only for ease of description this utility model rather than requires that therefore this utility model must be not construed as restriction of the present utility model with specific azimuth configuration and operation.
Refer to Fig. 1 and combine refering to shown in Fig. 2, this utility model provides and includes a kind of high sensitivity capacitor touch button, including: the high frequency constant current pulse generator (hereinafter referred to as " generator ") being electrical connected with inductance capacitance Cf in parallel and distribution capacity Cd and circuit of synchronous rectification (hereinafter referred to as " rectification circuit "), also include low pressure difference linear voltage regulator LDO(hereinafter referred to as " manostat "), power subsystem VCC and variable gain amplifier PGA(hereinafter referred to as " amplifier "), analog-digital converter ADC, digital to analog converter DAC and variable bandwidth low-pass ripple device (hereinafter referred to as " wave filter "), wherein: set up by manostat LDO between generator with power subsystem VCC and be connected；All set up by amplifier PGA between rectification circuit with analog-digital converter ADC and rectification circuit with digital to analog converter DAC and be connected, set up by wave filter between analog-digital converter ADC with digital to analog converter DAC simultaneously and be connected.In the present embodiment, inductance capacitance Cf is inductance capacitance during human finger touch, and distribution capacity Cd is the distribution capacity of touch controlled key sensing chip.
Referring again to shown in Fig. 2, this utility model provides a kind of method of high sensitivity capacitor touch button, including:
Power subsystem VCC produces the stable voltage power supply as generator through manostat LDO, generator produces the continuous impulse signal of frequency constant output current when being 1 ~ 8MHz high level and using this pulse signal as the pumping signal of touch controlled key, thus can get formula:
C=It/U；
Wherein C=Cf+Cd, I, t be respectively electric current and the high level time of generator, and U is the magnitude of voltage of touch controlled key port, namely the magnitude of voltage on electric capacity C.Owing to I and t is constant, as long as the value recording voltage U just can draw the size of electric capacity C, inductance capacitance Cf when thus human finger touches it is:
；
As Cd > Cf time, Δ U and Δ Cf is respectively the difference of U and Cf of two different times, but, the capacitance change of plain edition its Cf of touch controlled key is about between 5 ~ 50pf, and the Cf capacitance change applied every empty touch controlled key and matrix or human body proximity sensing etc. is generally less than 0.5pf, and the capacitance of Cd changes as well as the change of temperature and time, the variable quantity of its electric capacity is typically at about 0.1 ~ 1pf.So in order to stably detect the capacitance variations of below 0.5pf, it is impossible to by simply increasing the amplifier gain of circuit, because so can cause amplifier that saturation problem occurs.
Then, in this utility model, the detection method of high sensitivity capacitance touching control is, circuit is made up of rectification circuit, amplifier PGA, analog-digital converter ADC, wave filter and digital to analog converter DAC.It is converted into direct current signal through rectification circuit from the ac voltage signal of input input, amplify through amplifier PGA and be converted into digital signal through analog-digital converter ADC, in order to avoid amplifier PGA is saturated, need to extract in a digital signal the component of distribution capacity Cd, and it is delivered to after digital to analog converter DAC changes into analog quantity the negative terminal of amplifier PGA, thereby avoiding technical problem saturated for amplifier PGA, the gain increase of amplifier PGA makes the sensitivity of touch control detection be greatly improved.
In order to the component of distribution capacity Cd is effectively separated in the digital signal that analog-digital converter ADC exports, wave filter obtains by the change of inductance capacitance Cf and distribution capacity Cd is carried out spectrum analysis.In the present embodiment, the frequency of the inductance capacitance Cf change that human finger sensing causes is generally higher than 5Hz, and touch controlled key distribution capacity Cd can be generally less than 1Hz because of the frequency of the distribution capacity Cd change that environmental effect causes, therefore one preferable wave filter of spectral characteristic of employing just can the component extraction of distribution capacity Cd out, and the negative input end of amplifier PGA after being converted into analogue signal by digital to analog converter DAC, can be delivered to, so can efficiently extract out the component of inductance capacitance Cf.After above process, the digital signal value of final analog-digital converter ADC output can be represented by following equation:
VADC=k*Cf=G(U-k1*Cd)；
Wherein VADC is the output valve of analog-digital converter ADC, and k is the gain of whole touch control detection circuit, and G is the gain of amplifier PGA, and k1 is touch-control circuit input through the gain of amplifier PGA and wave filter to amplifier PGA negative terminal.Capacitance and the changing value thereof of touch controlled key so just can be obtained by the output valve of detection analog-digital converter ADC, owing to the gain in whole loop can reach more than 10 times of common touch control detection circuit gain, therefore use this detection method can realize highly sensitive touch control detection function.
In order to promote understanding, briefly describe each assembly function (such as Fig. 2) the most again:
Low pressure difference linear voltage regulator LDO, for producing a stable voltage, this voltage is as the power supply of high frequency constant current pulse generator；
High frequency constant current pulse generator is by can prescaler, 8 constant current switches of 8 output multi-channel selectores and different output current form；According to preset value, the system clock of chip internal can be divided prescaler the touch-control scan clock signal for setpoint frequency, clock signal gives 8 output multi-channel selectores and the circuit of synchronous rectification being made up of analog multiplier respectively；Touch-control scan clock signal is exported the control end of chosen constant current switch by 8 output multi-channel selectores according to the setting of central processor CPU, the high frequency constant-current pulse that so can be controlled by CPU at outfan one frequency of output and the electric current of constant current switch, this pulse exports touch controlled key sensing chip the driving source as touch control capacitance detection by the pin of chip；The parameter of prescaler and 8 output multi-channel selectores can set and be controlled by 8 pre-storages 3 and 8 pre-storages 4 by CPU；
High frequency constant-current pulse will produce an alternating voltage on touch controlled key sensing chip, its magnitude of voltage is inversely proportional to inductance capacitance Cf, distribution capacity Cd sum, and this signal produces a DC voltage U after the circuit of synchronous rectification being made up of analog multiplier on electric capacity Cmod.
Variable gain amplifier PGA has two inputs (positive input terminal and negative input end) and an outfan, and its gain amplifier is controlled by 8 pre-storages 1 by central processor CPU.The positive input terminal of variable gain amplifier is connected with the output of analog multiplier, its input voltage is voltage U, the negative input end of variable gain amplifier receives the analog output of 8 figure place weighted-voltage D/A converter DAC, the analog input end of 16 analog-digital converters is received in the output of variable gain amplifier, Vin=G (U-VOUT), wherein G is the gain amplifier of PGA；
Analog input voltage is converted into 16 bit digital quantity by 16 analog-digital converter ADC, and this digital signal is sent to CPU process.
Variable bandwidth low-pass ripple device includes that CPU, CPU i.e. start the bandwidth according to setting after reading the digital signal that ADC exports and gain carries out IIR low-pass filtering calculating, exports the numeral input as DAC of 8 pre-storages 2 after filtering the high fdrequency component in sampled signal.CPU carries out the bandwidth of digital low-pass filtering calculating and gain parameter can be according to different application scenario flexible configuration；
The digital quantity of input is converted to analog voltage and exports the negative input end of PGA by 8 figure place weighted-voltage D/A converter DAC.
The most each circuit module i.e. constitutes the touch control capacitance detecting system of a closed loop.
Claims (7)
1. a high sensitivity capacitor touch button, including the generator being electrical connected with inductance capacitance in parallel and distribution capacity and rectification circuit, also include manostat, power subsystem and amplifier, analog-digital converter, digital to analog converter and wave filter, it is characterised in that: set up by manostat between generator with power subsystem and be connected；All set up by amplifier between rectification circuit with analog-digital converter and rectification circuit with digital to analog converter and be connected, set up by wave filter between analog-digital converter with digital to analog converter simultaneously and be connected.
2. high sensitivity capacitor touch button as claimed in claim 1, it is characterised in that: inductance capacitance is to sense the electric capacity that human finger touches, and distribution capacity is touch controlled key sensing chip electric capacity.
3. high sensitivity capacitor touch button as claimed in claim 2, it is characterised in that: generator is high frequency constant current pulse generator, and including frequency divider, MUX and constant current switch, frequency divider is can prescaler.
4. high sensitivity capacitor touch button as claimed in claim 3, it is characterised in that: amplifier is variable gain amplifier, including positive input terminal and negative input end and outfan.
5. high sensitivity capacitor touch button as claimed in claim 4, it is characterised in that: wave filter is variable bandwidth low-pass ripple device, and including central processing unit, pre-storage, wherein: positive input terminal is connected with analog-digital converter, negative input end is connected with digital to analog converter.
6. high sensitivity capacitor touch button as claimed in claim 5, it is characterised in that: analog-digital converter uses 16 analog-digital converters, and digital to analog converter uses 8 figure place weighted-voltage D/A converters.
7. the high sensitivity capacitor touch button as described in any one of claim 1 to 6, it is characterised in that: rectification circuit is circuit of synchronous rectification.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620320963.4U CN205620981U (en) | 2016-04-14 | 2016-04-14 | High sensitivity electric capacity touch key |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201620320963.4U CN205620981U (en) | 2016-04-14 | 2016-04-14 | High sensitivity electric capacity touch key |
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| CN205620981U true CN205620981U (en) | 2016-10-05 |
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| CN201620320963.4U Active CN205620981U (en) | 2016-04-14 | 2016-04-14 | High sensitivity electric capacity touch key |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107819444A (en) * | 2017-10-20 | 2018-03-20 | 昆山龙腾光电有限公司 | Voltage signal amplifying circuit |
| CN110380715A (en) * | 2018-04-12 | 2019-10-25 | 深圳市赛元微电子有限公司 | A kind of detection method and detection device of capacitance type touch control keys |
-
2016
- 2016-04-14 CN CN201620320963.4U patent/CN205620981U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107819444A (en) * | 2017-10-20 | 2018-03-20 | 昆山龙腾光电有限公司 | Voltage signal amplifying circuit |
| CN110380715A (en) * | 2018-04-12 | 2019-10-25 | 深圳市赛元微电子有限公司 | A kind of detection method and detection device of capacitance type touch control keys |
| CN110380715B (en) * | 2018-04-12 | 2021-11-23 | 深圳市赛元微电子有限公司 | Detection method and detection device for capacitive touch key |
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Address after: B610, Zhongdi building, industry university research base, China University of Geosciences, No.8, Yuexing Third Road, South District, high tech Zone, Nanshan District, Shenzhen, Guangdong 518000 Patentee after: Shenzhen Saiyuan Microelectronics Co.,Ltd. Address before: B610, Zhongdi building, industry university research base, China University of Geosciences, No.8, Yuexing Third Road, South District, high tech Zone, Nanshan District, Shenzhen, Guangdong 518000 Patentee before: SHENZHEN SINONE CHIP ELECTRONIC Co.,Ltd. |