CN101888234B - Human touch detection circuit - Google Patents
Human touch detection circuit Download PDFInfo
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- CN101888234B CN101888234B CN2009100512691A CN200910051269A CN101888234B CN 101888234 B CN101888234 B CN 101888234B CN 2009100512691 A CN2009100512691 A CN 2009100512691A CN 200910051269 A CN200910051269 A CN 200910051269A CN 101888234 B CN101888234 B CN 101888234B
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Abstract
The invention discloses a human touch detection circuit, which consists of a first oscillating circuit, a second oscillating circuit, a sequential control circuit, a counter, a first register, a second register, a third register and a comparator. The first oscillating circuit, a first resistor and a first capacitor work under the same environment as the second oscillating circuit, a second resistor and a second capacitor. When a human body contacts a human touch terminal connected on the second oscillating circuit, because the human body has parasitic capacitance to the ground, the frequency of the second oscillating circuit is changed. A digital circuit composed of the sequential control circuit, the counter, the registers and the comparator accurately judges whether the human body contacts the human touch terminal according to the frequency difference of output signals of the second oscillating circuit before and after the human touch. The human touch detection circuit can eliminate the environmental influence, and has the advantages of strong anti-jamming capability and stable work.
Description
Technical field:
The present invention relates to electricity field, relate in particular to digital circuit, particularly a kind of human touch detection circuit.
Background technology:
In the prior art, a large amount of electrical installations adopt human touch detection circuit as the sense switch device.Traditional active induction type human touch detection circuit is made of RC oscillator and shaping circuit, one end ground connection of RC oscillator, under the normality, the RC oscillator is to shaping circuit periodicity output low level signal and high level signal, and the output of shaping circuit produces the periodic pulse signal that has comprised high and low level signal.During node in human body touch RC oscillator between resistor and the capacitor, because human body has certain electric capacity over the ground, suitably the value of design R and C can make RC oscillator output low level signal all the time, like this, the output of shaping circuit often is a low level, utilize digital circuit often to be low level signal and have the pulse signal of certain frequency to be distinguished, the purpose of no touch is arranged to reach human body.But sort circuit is subjected to the influence of nature environment such as weather, humidity easily, and a little less than the antijamming capability, stability and practicality are all undesirable.
Summary of the invention:
The object of the present invention is to provide a kind of human touch detection circuit, described this human touch detection circuit will solve in the prior art initiatively that the induction type human touch detection circuit is subjected to easily that the influence of nature environment such as weather, humidity, antijamming capability are weak, stability and the unfavorable technical problem of practicality.
This human touch detection circuit of the present invention is made of one the one RC oscillator, the 2nd a RC oscillator and a digitlization comparison circuit, wherein, a described RC oscillator, the 2nd RC oscillator are connected with described digitlization comparison circuit, the 2nd RC oscillator is connected with a human body touch terminal, the frequency difference of digitlization comparison circuit comparison the 2nd RC oscillator before and after the human body touch terminal is touched differentiated the generation of human body touch incident.
Further, a described RC oscillator is made of one first oscillating circuit, described the 2nd RC oscillator is made of one second oscillating circuit, described digitlization comparison circuit is by a sequential control circuit, a counter, one first register, one second register, one the 3rd register and a comparator constitute, be provided with a clock signal input terminal in the described sequential control circuit, an electrification reset end, a comparison control end, one first register latchs end, one second register latchs end, one the 3rd register latchs end and a counter reset end, be provided with a clock signal input terminal in the described counter, an output and a reset signal end, the signal input part of described first oscillating circuit is connected with an end of one first resistor and an end of one first capacitor, the other end of described first resistor is a power end, the other end of described first capacitor is an earth terminal, the signal output part of first oscillating circuit is connected with the clock signal input terminal of described sequential control circuit, the comparison control end of sequential control circuit is connected with described comparator, first register of sequential control circuit latchs end and is connected with the end that latchs of described first register, second register of sequential control circuit latchs end and is connected with the end that latchs of described second register, the 3rd register of sequential control circuit latchs end and is connected with the end that latchs of described the 3rd register, the counter reset end of sequential control circuit is connected with the reset signal end of described counter, one end of the signal input part of described second oscillating circuit and one second resistor, one end of one second capacitor is connected with a human body touch terminal, the other end of described second resistor is a power end, the other end of described second capacitor is an earth terminal, the signal output part of second oscillating circuit is connected with the clock signal input terminal of counter, the output of counter is connected to first register simultaneously, the input of second register and the 3rd register, the output of first register, the output of second register, the output of the 3rd register all is connected with comparator.
Concrete, first oscillating circuit described in the present invention, second oscillating circuit, sequential control circuit, counter, first register, second register, the 3rd register and comparator all adopt known technology of the prior art, relevant above-mentioned known solution, those skilled in the art all understands, does not repeat them here.
Operation principle of the present invention is: first oscillating circuit, first resistor and first capacitor and second oscillating circuit, second resistor and second capacitor are operated under the equivalent environment, when the human body touch termination contact that is connected on human body and second oscillating circuit, because human body has parasitic capacitance over the ground, therefore changed the frequency of second oscillating circuit.The digital circuit that sequential control circuit, counter, register and comparator are formed judges accurately according to the frequency difference of the second oscillating circuit output signal before and after human body touch whether human body contacts the human body touch terminal.
The present invention compares with prior art, and its effect is actively with tangible.The present invention utilizes the digital circuit human body to touch the variation of the RC oscillator frequency that causes, realizes the detection to human body touch.The oscillating circuit output signal before and after the human body touch this institute is much at one affected by environment in a short time, therefore can eliminate environmental impact, antijamming capability is strong, working stability.
Description of drawings:
Fig. 1 is the schematic diagram of a kind of human touch detection circuit of the present invention.
Fig. 2 is the output waveform figure of the sequential control circuit among the embodiment of a kind of human touch detection circuit of the present invention.
Embodiment:
Embodiment 1:
As shown in Figure 1, a kind of human touch detection circuit of the present invention, by one first oscillating circuit 1, one second oscillating circuit 2, a sequential control circuit 3, a counter 4, one first register 5, one second register 6, one the 3rd register 7 and a comparator 8 constitute, be provided with a clock signal input terminal clk1 in the described sequential control circuit 3, an electrification reset end POR, a comparison control end CB, one first register latchs end L1, one second register latchs end L2, one the 3rd register latchs end L3 and a counter reset end R, be provided with a clock signal input terminal clk2 in the described counter 4, an output and a reset signal end R, wherein, the signal input part of described first oscillating circuit 1 is connected with an end of one first resistor R 1 and the end of one first capacitor C1, the other end of described first resistor R 1 is power end vdd, the other end of the described first capacitor C1 is earth terminal gnd, the signal output part of first oscillating circuit 1 is connected with the clock signal input terminal clk1 of described sequential control circuit 3, the comparison control end CB of sequential control circuit 3 is connected with described comparator 8, first register of sequential control circuit 3 latchs end L1 and is connected with the end that latchs of described first register 5, second register of sequential control circuit 3 latchs end L2 and is connected with the end that latchs of described second register 6, the 3rd register of sequential control circuit 3 latchs end L3 and is connected with the end that latchs of described the 3rd register 7, the counter reset end of sequential control circuit 3 is connected with the reset signal end R of described counter 4, one end of the signal input part of described second oscillating circuit 2 and one second resistor R 2, the end of one second capacitor C2 is connected with a human body touch terminal T, the other end of described second resistor R 2 is power end vdd, the other end of the described second capacitor C2 is earth terminal gnd, the signal output part of second oscillating circuit 2 is connected with the clock signal input terminal clk2 of counter 4, the output of counter 4 is connected to first register 5 simultaneously, the input of second register 6 and the 3rd register 7, the output of first register 5, the output of second register 6, the output of the 3rd register 7 all is connected with comparator 8.
Further, the structure and parameter of the structure and parameter of described first oscillating circuit 1 and second oscillating circuit 2 can be identical, and the parameter of first resistor R 1 and second resistor R 2 can be identical, and the parameter of the first capacitor C1 and the second capacitor C2 can be identical.
Operation principle of the present invention is: first oscillating circuit 1, first resistor R 1 and the first capacitor C1 and second oscillating circuit 2, second resistor R 2 and the second capacitor C2 are operated under the equivalent environment, when the human body touch terminal T contact that is connected on human body and second oscillating circuit 2, because human body has parasitic capacitance over the ground, therefore changed the frequency of second oscillating circuit 2.The digital circuit that sequential control circuit 3, counter 4, register and comparator 8 are formed is according to the frequency difference of the second oscillating circuit output signal before and after human body touch, promptly first register 5, second register 6 are different with the value that the 3rd register 7 is latched, and relatively come accurately to judge whether human body contacts human body touch terminal T through comparator 8.
Concrete, the operation principle and the course of work of present embodiment are as follows:
When circuit had just powered on, electrify restoration circuit output signal POR acted on sequential control circuit 3, and the counter reset end R of sequential control circuit 3 is resetted to counter 4.Sequential control circuit 3 other ends output is control end CB relatively, makes value homogeneous phase that the value of comparator 8 outputs equals first register 5, second register 6, the 3rd register 7 value that should export of comparator 8 simultaneously.As the value homogeneous phase while of first register 5, second register 6 and the 3rd register 7, it is " 0 " that comparator 8 is answered output valve, when then circuit has just powered on, and comparator 8 outputs " 0 "; As the value homogeneous phase while of first register 5, second register 6, the 3rd register 7, it is " 1 " that comparator 8 is answered output valve, when then circuit has just powered on, and comparator 8 outputs " 1 ".
After the power-on reset signal POR effect sequential control circuit 3, through several CLK1 week after dates, sequential control circuit 3 output R, L1, L2 and L3, the waveform of R, L1, L2 and L3 is as shown in Figure 2.Suppose, when R was " 1 ", counter 4 resetted, when L1, L2 and L3 are trailing edge, make the output OUT of first register 5, second register 6,7 pairs of counters 4 of the 3rd register carry out data sampling respectively, otherwise " 0 " in Fig. 2 waveform all carry out anti-phase with " 1 ".L1, L2 and L3 all are to be the scan period signal with fixed frequency of reference with the CLK1 cycle, in Fig. 2, and each T1T2T3 scan period, to L1, L2 and each trailing edge of L3, be respectively T1, T2, T3 from the trailing edge of R, all on time span, equate.Constant at first T1T2T3 cycle CB signal, so the output of comparator 8 is identical during with electrification reset.
Since second T1T2T3 scan period, CB makes comparator 8 work, as long as the value that the output valve of first register 5, second register 6,7 pairs of counters 4 of the 3rd register is sampled have any 2 inequality, then comparator 8 just has the output of the value when being different from electrification reset.If comparator 8 is output as " 0 " during electrification reset, then this moment, comparator 8 was output as " 1 " if the value difference of any two registers is arranged, and comparator 8 is output as " 1 " during as if electrification reset, then this moment, comparator 8 was output as " 0 " if the value difference of any two registers is arranged.
Concrete, when first register 5, second register 6, the 3rd register 7 are sampled to the output OUT of counter 4 respectively at the trailing edge of L1, L2, L3, only the high-order portion of counter 4 is sampled, low portion then is presented as touching the tolerance of end.Be that output valve is the high-order portion of counter 4, and touch the low portion that only is embodied in counter 4 when end has small variation, thereby realize the stability and the antijamming capability of touch detection circuit.
During human body touch T end, because human body has electric capacity or extra interference signal over the ground, suitably design the value of C2, can make CLK2 (being the input of the counter 4) cycle that bigger change is arranged, thereby cause the variation of counter 4 high-order portions, so the output valve of first register 5, second register 6,7 pairs of counters 4 of the 3rd register value of sampling just have two inequality, make comparator 8 that the output of the value when being different from electrification reset be arranged, thereby realize the detection of human body touch.
The precision and the antijamming capability that touch can be relevant with following the example of of counter 4 figure places and output valve, and certainly with the value of R2, C2, and the length of the scan period of R1, C1 and sequential control circuit 3 also has the relation of interwoveness.
Claims (1)
1. human touch detection circuit, by one the one RC oscillator, one the 2nd RC oscillator and a digitlization comparison circuit constitute, it is characterized in that: a described RC oscillator, the 2nd RC oscillator is connected with described digitlization comparison circuit, the 2nd RC oscillator is connected with a human body touch terminal, the frequency difference of digitlization comparison circuit comparison the 2nd RC oscillator before and after the human body touch terminal is touched, differentiate the generation of human body touch incident, a described RC oscillator is made of one first oscillating circuit, described the 2nd RC oscillator is made of one second oscillating circuit, described digitlization comparison circuit is by a sequential control circuit, a counter, one first register, one second register, one the 3rd register and a comparator constitute, be provided with a clock signal input terminal in the described sequential control circuit, an electrification reset end, a comparison control end, one first register latchs end, one second register latchs end, one the 3rd register latchs end and a counter reset end, be provided with a clock signal input terminal in the described counter, an output and a reset signal end, the signal input part of described first oscillating circuit is connected with an end of one first resistor and an end of one first capacitor, the other end of described first resistor is a power end, the other end of described first capacitor is an earth terminal, the signal output part of first oscillating circuit is connected with the clock signal input terminal of described sequential control circuit, the comparison control end of sequential control circuit is connected with described comparator, first register of sequential control circuit latchs end and is connected with the end that latchs of described first register, second register of sequential control circuit latchs end and is connected with the end that latchs of described second register, the 3rd register of sequential control circuit latchs end and is connected with the end that latchs of described the 3rd register, the counter reset end of sequential control circuit is connected with the reset signal end of described counter, one end of the signal input part of described second oscillating circuit and one second resistor, one end of one second capacitor is connected with a human body touch terminal, the other end of described second resistor is a power end, the other end of described second capacitor is an earth terminal, the signal output part of second oscillating circuit is connected with the clock signal input terminal of counter, the output of counter is connected to first register simultaneously, the input of second register and the 3rd register, the output of first register, the output of second register, the output of the 3rd register all is connected with comparator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100512691A CN101888234B (en) | 2009-05-14 | 2009-05-14 | Human touch detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009100512691A CN101888234B (en) | 2009-05-14 | 2009-05-14 | Human touch detection circuit |
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| CN101888234A CN101888234A (en) | 2010-11-17 |
| CN101888234B true CN101888234B (en) | 2011-12-14 |
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| CN2009100512691A Expired - Fee Related CN101888234B (en) | 2009-05-14 | 2009-05-14 | Human touch detection circuit |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108563358B (en) * | 2018-04-10 | 2021-12-07 | 刘兵 | Touch detection method and touch detection circuit thereof |
| KR102185046B1 (en) * | 2019-07-03 | 2020-12-01 | 삼성전기주식회사 | Switching operatiion sensing apparatus capable of identifying a touch object, and electronic devices |
| CN110347294B (en) * | 2019-07-19 | 2023-05-16 | 湖南品腾电子科技有限公司 | Capacitive touch detection circuit and method |
| CN115276620A (en) * | 2022-09-27 | 2022-11-01 | 上海海栎创科技股份有限公司 | Capacitive touch key analog front-end circuit and touch structure |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0478856A1 (en) * | 1990-10-01 | 1992-04-08 | Siemens Aktiengesellschaft Österreich | Method and device for controlling the activation of a touch plate |
| CN1771430A (en) * | 2003-02-10 | 2006-05-10 | N-特莱格有限公司 | Touch detection for a digitizer |
| US7307485B1 (en) * | 2005-11-14 | 2007-12-11 | Cypress Semiconductor Corporation | Capacitance sensor using relaxation oscillators |
-
2009
- 2009-05-14 CN CN2009100512691A patent/CN101888234B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0478856A1 (en) * | 1990-10-01 | 1992-04-08 | Siemens Aktiengesellschaft Österreich | Method and device for controlling the activation of a touch plate |
| CN1771430A (en) * | 2003-02-10 | 2006-05-10 | N-特莱格有限公司 | Touch detection for a digitizer |
| US7307485B1 (en) * | 2005-11-14 | 2007-12-11 | Cypress Semiconductor Corporation | Capacitance sensor using relaxation oscillators |
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| CN101888234A (en) | 2010-11-17 |
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