CN1536467A - Key input circuit - Google Patents
Key input circuit Download PDFInfo
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- CN1536467A CN1536467A CNA031094511A CN03109451A CN1536467A CN 1536467 A CN1536467 A CN 1536467A CN A031094511 A CNA031094511 A CN A031094511A CN 03109451 A CN03109451 A CN 03109451A CN 1536467 A CN1536467 A CN 1536467A
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Abstract
The invention relates to a key input circuit, using scanning converting device to separate the key input mechanism from the grounding end of the microcomputer, in order to make the microcomputer able to identify the input keys. It generally includes key input mechanism, scanning converting device, amplifying mechanism and microcomputer. The key input mechanism outputs a certain divided voltage according to the states of switches respectively connected with a specific number of resistors; the scanning converting device makes a switching voltage of the key input mechanism generated on the primary side, where the switching voltage varies with the switch driving signal and the key input mechanism is connected on the secondary side; the amplifying mechanism is connected on primary side of the scanning converting device and amplifies the above-mentioned switching voltage into a certain voltage for output; the microcomputer outputs the switch driving signal and determines the output voltage from the amplifying mechanism as the switching voltage of the key input mechanism, and then controls the determination.
Description
Technical field
The present invention relates to a kind of button inputting circuits, furtherly, then relate to a kind of button inputting circuits that can bring following effect: use scanning converter unit (Flyback Converter) that the earth terminal of button input mechanism and microcomputer is separated, make that microcomputer can the cognitive button of importing.
Background technology
With reference to the accompanying drawings, the structure to the button inputting circuits of prior art describes.
Fig. 1 demonstrates the circuit diagram of the structure of prior art button inputting circuits.
Generally widely used button inputting circuits comprises button input mechanism 11, filter mechanism 12 and microcomputer 13 substantially on the microcomputer of household appliances.
As shown in Figure 1, be connected the state of the ohmically switch of certain number, the voltage drop difference of supply voltage (5V) output on switch, output branch pressure voltage according to above-mentioned button input mechanism 11; The noise that above-mentioned filter mechanism 12 is removed the output voltage of above-mentioned button input mechanism 11 is exported then; Above-mentioned microcomputer 13 converts the output voltage of above-mentioned filter mechanism 12 to digital signal, judges the input state of switch, and controls according to above-mentioned input state.
At first, above-mentioned button input mechanism 11 has adopted switch SW 1～SW4 has been connected on the resistance R 1～R4 with mutual different resistance values, supply voltage (5V) is carried out the mode of dividing potential drop.
Above-mentioned button input mechanism 11 is ' strong ' button by first switch SW, 1 input of connecting with the resistance R 1 with intrinsic resistance value; Second switch SW2 input by connecting with resistance R 2 ' in ' button; The 3rd switch SW 3 input by connecting with resistance R 3 ' weak ' button, import by the 4th switch SW 4 of connect and ' to stop ' button with resistance R 4.
At this moment (SW1～SW3), the magnitude of current that flows through on the light emitting diode (LED) is also different, so the brightness difference of above-mentioned LED according to above-mentioned first～the 3rd switch of being imported; According to the On/Off of above-mentioned the 4th switch SW 4, above-mentioned light emitting diode (LED) is also followed On/Off.
Wherein, when above-mentioned the 4th switch SW 4 was in closed condition, above-mentioned light emitting diode had the voltage drop of about 1.5V; When above-mentioned the 4th switch SW 4 is in opening, above-mentioned LED has the voltage drop of about 1.8V, so press above-mentioned first～the 4th switch (Vi of voltage for the moment of SW1～SW4), and do not press above-mentioned first～the 4th switch (mathematical expression such as the following mathematical expression 1 of the voltage of any one switch (NONE) among the SW1～SW4).
Mathematical expression 1
The operating voltage level Vi of above-mentioned first～the 4th switch shown in above-mentioned mathematical expression 1 equals the voltage drop on decline (pull down) resistance R d, above-mentioned magnitude of voltage is input to above-mentioned microcomputer 13, and above-mentioned microcomputer 13 thinks that above-mentioned magnitude of voltage is the input of first～the 4th switch.
But, in above-mentioned prior art button inputting circuits, has following shortcoming: the earth terminal common ground of the earth terminal of above-mentioned microcomputer and button input mechanism, so when above-mentioned microcomputer earthing potential self has certain potentials, be generally the earthing potential after the power rectifier commonly used, the danger of electric shock arranged easily.
Summary of the invention
The present invention is for the problem that solves above-mentioned prior art proposes, and the objective of the invention is to provide the button inputting circuits that can bring following effect:
Utilize scanning converter unit microcomputer to be set at primary side; At secondary side the button input mechanism is set; According to the button operation of secondary side button input mechanism, detect the peak value on the primary side main switch, be input to microcomputer.So the earth terminal of above-mentioned button input mechanism and the earth terminal of microcomputer are separated the generation that has prevented electric shock accidents fully.
In order to realize the purpose of the invention described above, the invention provides a kind of button inputting circuits that following structure is a feature that has: button inputting circuits of the present invention comprises button input mechanism, scanning converter unit, scaling device and microcomputer substantially.Above-mentioned button input mechanism is exported certain branch pressure voltage according to the state that is connected to the ohmically switch of certain number; Above-mentioned scanning converter unit makes the switching voltage of the button input mechanism that is connected secondary side that changes according to switching drive signal be created in primary side; Above-mentioned scaling device is connected the primary side of above-mentioned scanning converter unit, and the voltage scaling that above-mentioned primary side is produced becomes certain voltage to export; Above-mentioned microcomputer is exported above-mentioned switching drive signal, and the output voltage of above-mentioned scaling device is judged as the switching voltage of above-mentioned button input mechanism, then above-mentioned judgement is controlled.
Therefore, the present invention has utilized scanning converter unit, be provided with microcomputer at primary side, be provided with the button input mechanism at secondary side, the crest voltage at the primary side main switch two ends that produce by the button operation that detects secondary side button input mechanism, be input to microcomputer,, prevented the electric shock phenomenon so separated the earth terminal of button input mechanism and the earth terminal of microcomputer fully.
Description of drawings
Fig. 1 demonstrates the circuit diagram of the structure of prior art button inputting circuits;
Fig. 2 demonstrates the circuit diagram of the structure of button inputting circuits of the present invention;
Fig. 3 demonstrates the oscillogram that the switching manipulation of button inputting circuits of the present invention causes.
The critical piece description of reference numerals
21: button input mechanism 22: scanning converter unit (flyback convertor)
23: scaling device (scaling) 24: microcomputer
SW1～SW4: first～the 4th switch R11～R14, Rd: resistance
Q1: main switch
Embodiment
Illustrated embodiment with reference to the accompanying drawings, button inputting circuits of the present invention is elaborated.
Fig. 2 demonstrates the circuit diagram of the structure of button inputting circuits of the present invention.
As shown in Figure 2, button inputting circuits of the present invention comprises button input mechanism 21, scanning converter unit 22, scaling device (scaling) 23 and microcomputer 24 substantially.Above-mentioned button input mechanism 21 is according to the certain branch pressure voltage of state output of the ohmically switch that is connected to certain number; Above-mentioned scanning converter unit 22 makes the switching voltage of the button input mechanism 21 that is connected secondary side that changes according to switching drive signal be created in primary side; Above-mentioned scaling device 23 is connected the primary side of above-mentioned scanning converter unit 22, and the voltage scaling that above-mentioned primary side is produced becomes certain voltage to export; The above-mentioned switching drive signal of above-mentioned microcomputer 24 outputs is judged as the switching voltage of above-mentioned button input mechanism 21 with the output voltage of above-mentioned scaling device 23, then above-mentioned judgement is controlled.
In the present invention, the secondary side at above-mentioned scanning converter unit 22 is provided with above-mentioned button input mechanism 21; Primary side at above-mentioned scanning converter unit 22 is provided with above-mentioned scaling device 23; Above-mentioned microcomputer 24 identifications are by the branch pressure voltage of above-mentioned scaling device 23 outputs.
At first, as an embodiment, (SW1～SW4) go up after difference resistance in series R11～R14 carries out parallel connection with them to first of above-mentioned button input mechanism 21～the 4th switch.
In addition, as first of secondary side～the 4th switch (SW11～when SW14) all being in opening, primary side produces infinitely-great voltage in theory, so be connected with the resistance R d that plays the load effect, purpose is that primary side produces infinitely-great voltage when preventing that above-mentioned switch SW 11～SW14 is in opening.
At this moment, the switch SW 11～SW14 that is connected on the resistance R 11～R14 with intrinsic resistance value starts, and then passes through the load of the crest voltage perception secondary side variation at main switch Q1 two ends.
Below with reference to Fig. 3, button inputting circuits of the present invention is described in more detail.
Fig. 3 demonstrates the oscillogram that the switching manipulation of button inputting circuits of the present invention causes.
Shown in the A among Fig. 3, above-mentioned microcomputer 24 has been transfused to the 5V output voltage of above-mentioned scaling device 23; Is above-mentioned microcomputer 24 3 with frequency, the unlatching duty (On Duty) of 33KHz?, to close duty (Off Duty) be 30? drive above-mentioned main switch Q1.
At this moment, for the load that makes above-mentioned secondary side becomes little load, need make electric current discontinuous mobile, so above-mentioned scanning converter unit 22 is worked according to discontinuous mode (Discontinuous mode), the load of secondary side produces inverse ratio moral crest voltage on the then above-mentioned main switch Q1 two ends, to meet the voltage that alleviates above-mentioned main switch Q1 and will increase in order to make.
The B of Fig. 3 demonstrates when above-mentioned switch SW 11～SW14 opens, the voltage oscillogram at detected crest voltage and above-mentioned main switch Q1 two ends at this moment, compare with the two ends crest voltage of the above-mentioned main switch Q1 of reality, because how many voltage drops that resistance produces there are differences.
Shown in the C of Fig. 3, when pressing above-mentioned first switch SW 1, above-mentioned microcomputer 24 drives above-mentioned main switch Q1 according to the unlatching working time after closing duty, the crest voltage at this moment above-mentioned main switch Q1 two ends is kept the minimum first peak threshold voltage of certain hour.
Shown in the D of Fig. 3, when pressing above-mentioned second switch SW2, above-mentioned microcomputer 24 drives above-mentioned main switch Q1 according to the unlatching working time after closing duty, the crest voltage at this moment above-mentioned main switch Q1 two ends is kept certain hour according to second crest voltage bigger a little than first peak threshold voltage.
E among Fig. 3 is the crest voltage that above-mentioned main switch Q1 two ends produce when pressing the 3rd switch SW 3, and the F among Fig. 3 is the crest voltage that above-mentioned main switch Q1 two ends produce when pressing the 4th switch SW 4.
Final above-mentioned crest voltage is input to above-mentioned microcomputer 24, the on off state of the above-mentioned button input mechanism 21 of perception, and control according to sensing results.
So, utilize the discontinuous mobile discontinuous mode of electric current to start scanning converter unit in the present invention, the crest voltage at the two ends of the primary side main switch by above-mentioned scanning converter unit, perception secondary side load, the on off state of perception secondary side button input mechanism.
Claims (4)
1, a kind of button inputting circuits is characterized in that, comprising:
Button input mechanism, scanning converter unit;
Above-mentioned button input mechanism is exported certain branch pressure voltage according to the state that is connected to the ohmically switch of certain number;
Above-mentioned scanning converter unit makes the switching voltage of the button input mechanism that is connected secondary side that changes according to switching drive signal be created in primary side;
Above-mentioned scaling device is connected the primary side of above-mentioned scanning converter unit, and the voltage scaling that above-mentioned primary side is produced becomes certain voltage to export;
Above-mentioned microcomputer is exported above-mentioned switching drive signal, and the output voltage of above-mentioned scaling device is judged as the switching voltage of above-mentioned button input mechanism, then above-mentioned judgement is controlled.
2, button inputting circuits according to claim 1 is characterized in that:
Above-mentioned microcomputer will be after the unlatching interval of switching drive signal be thought switching voltage at the voltage that closes the detected scaling device in closed interval.
3, button inputting circuits according to claim 1 is characterized in that:
In above-mentioned scaling device, promoting a be connected in series side of first electric capacity of a side that resistance (Rup) and decline resistance (Rdn) contacts; The empty same ground connection of the opposite side of the opposite side of above-mentioned lifting resistance and decline resistance and above-mentioned first electric capacity; On the tie point of above-mentioned lifting resistance and decline resistance, be connected second electric capacity; The opposite side of above-mentioned second electric capacity is connected above-mentioned sky with on the earth terminal.
4, button inputting circuits according to claim 1 and 2 is characterized in that:
Above-mentioned switching voltage is the crest voltage that is created in the primary side of scanning converter unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031094511A CN100334528C (en) | 2003-04-11 | 2003-04-11 | Key input circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB031094511A CN100334528C (en) | 2003-04-11 | 2003-04-11 | Key input circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1536467A true CN1536467A (en) | 2004-10-13 |
| CN100334528C CN100334528C (en) | 2007-08-29 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB031094511A Expired - Fee Related CN100334528C (en) | 2003-04-11 | 2003-04-11 | Key input circuit |
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| Country | Link |
|---|---|
| CN (1) | CN100334528C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101312341B (en) * | 2007-05-24 | 2010-06-23 | 明基电通股份有限公司 | Input device |
| CN112702047A (en) * | 2021-01-04 | 2021-04-23 | 长江存储科技有限责任公司 | Switching device, integrated circuit, and electronic apparatus |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58213330A (en) * | 1982-06-07 | 1983-12-12 | Victor Co Of Japan Ltd | Key input discriminating device |
| US4918634A (en) * | 1987-02-23 | 1990-04-17 | Minolta Camera Kabushiki Kaisha | Key input apparatus |
| JP3282666B2 (en) * | 1998-01-26 | 2002-05-20 | 株式会社ケンウッド | Electronics |
| CN1109290C (en) * | 1999-12-14 | 2003-05-21 | 达方电子股份有限公司 | Key scanning circuit |
| CN1399181A (en) * | 2002-09-10 | 2003-02-26 | 天津大学 | Keyboard signal processing method and keyboard signal circuit |
-
2003
- 2003-04-11 CN CNB031094511A patent/CN100334528C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101312341B (en) * | 2007-05-24 | 2010-06-23 | 明基电通股份有限公司 | Input device |
| CN112702047A (en) * | 2021-01-04 | 2021-04-23 | 长江存储科技有限责任公司 | Switching device, integrated circuit, and electronic apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100334528C (en) | 2007-08-29 |
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Granted publication date: 20070829 Termination date: 20120411 |