CN1263347C - Earphone detecting circuit - Google Patents
Earphone detecting circuit Download PDFInfo
- Publication number
- CN1263347C CN1263347C CN 02107551 CN02107551A CN1263347C CN 1263347 C CN1263347 C CN 1263347C CN 02107551 CN02107551 CN 02107551 CN 02107551 A CN02107551 A CN 02107551A CN 1263347 C CN1263347 C CN 1263347C
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- Prior art keywords
- earphone
- resistance
- electrically connected
- detecting circuit
- transistor
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Abstract
The present invention relates to an earphone detecting circuit which is provided with a transistor, a first resistor, a second resistor, a third resistor and a detector, wherein the transistor has a first end, a second end, a third end and a fourth end, and the first end is electrically connected with the fourth end, and is electrically connected to operating voltage. One end of a first resistor is electrically connected to the first end of the transistor, and the other end of the first resistor is electrically connected with the second end of the transistor. One end of a second resistor is electrically connected to the third end of the transistor, and the other end of the second resistor is connected to the ground. One end of a third resistor is electrically connected to the second end of the transistor, and the other end of the third resistor is electrically connected to the detection end of a drive circuit of the earphone. One end of a capacitor is electrically connected to the second end of the transistor, and the other end of the capacitor is connected to the ground. The detector is electrically connected to the third end of the transistor.
Description
Technical field
The invention relates to a kind of earphone detecting circuit, and particularly relevant for the earphone detecting circuit of holding of a kind of left and right acoustic channels when earphone can't actual ground connection the time commonly.
Background technology
Present employed various audio frequency generators, for example: radio-tape recorder, videocorder, TV, even portable computer etc., major part all can provide two kinds of audio frequency output channels, wherein one be the loudspeaker of these audio frequency generators in inner organizational system, another kind then is an earphone jack, can adopt different audio frequency to listen to mode in response to different environmental demands to make things convenient for the user.In addition, generally these audio frequency generators all can provide the automatic switchover audio frequency to listen to the function of mode.In other words, when the audio frequency generator is found in the earphone jack earphone of insertion or other circumscribed output device to be arranged, audio signal will be transferred in the circumscribed output device via earphone jack; Otherwise when not inserting any device in the earphone jack, audio signal will be changeed automatically by the loudspeaker of its inner organizational system and exported.
Yet, in order to reach the function of above-mentioned automatic switchover outgoing route, just must have and can match, in order to an earphone detecting circuit whether existing of detecting earphone (or other circumscribed output device) with the earphone drive circuit.Please refer to Fig. 1, it has shown the earphone detecting circuit of known employed a kind of earphone drive circuit and corresponding use.In Fig. 1, the audio signal of left and right acoustic channels is amplified by amplifier 102 and 104 respectively, filters dc noise through electric capacity 106 and 108 respectively more afterwards, is transferred on the earphone via contact 118 and 120 respectively at last.When earphone inserted as yet, contact 124 contacted with audio signal transmission wire 112, and since the resistance value of resistance 122 much larger than the relation of the resistance value of resistance 126, so detector 130 is about 0 via detecting circuit 132 received voltages.Under this situation, detector 130 can judge that earphone does not insert, so audio signal just can not transmitted via earphone drive circuit as shown in Figure 1.After earphone inserted, contact 124 can be by the headset plug top from audio signal transmission wire 112, so detector 130 received voltages are about V
CcUnder this situation, detector 130 can interpretation be that earphone inserts, so audio signal will be transmitted via the earphone drive circuit.
Though all seem all very normal, yet in order to obtain frequency response preferably, electric capacity 106 and 108 volume all can be done greatlyyer.In this case, the overall volume of earphone drive circuit just can't effectively be reduced.
In order to address this problem, the someone proposes a kind of earphone drive circuit that does not need electric capacity, shown in Fig. 2 A.Owing to be to utilize midpoint potential to hold altogether on this earphone drive circuit, so can't use as the resistance 122 of Fig. 1 and 126 and detect circuit 132 and form earphone detecting circuit 230.Therefore, must have a kind of can be on the earphone drive circuit shown in Fig. 2 A operable earphone detecting circuit 230.
In sum, the defective of known technology can be divided into two kinds haply, though a kind of be can detect earphone whether to exist, the circuit volume is bigger; Though another kind then is that the circuit volume is less, can't effectively detects earphone and whether exist.
Summary of the invention
The objective of the invention is to propose a kind of earphone detecting circuit, it can effectively operate on the earphone drive circuit shown in Fig. 2 A, and whether the right judgement earphone exists, so that audio signal can be along correct path output.
For achieving the above object, the present invention proposes a kind of earphone detecting circuit, and it is applicable to the Plug Action of detecting earphone in the earphone drive circuit.Wherein, the earphone drive circuit comprises L channel end, R channel end, virtual ground end and sense terminal.Earphone detecting circuit then comprises transistor, several resistance, an electric capacity and a detector.Transistor has four links, and first end and the 4th end electrically connect, and are electrically connected to operating voltage simultaneously.One end of first resistance is electrically connected to transistorized first end, and the other end of first resistance is electrically connected to transistorized second end.One end of second resistance is electrically connected to transistorized the 3rd end, and the other end ground connection of second resistance.One end of the 3rd resistance is electrically connected to transistorized second end, and the other end of the 3rd resistance is electrically connected at the sense terminal of aforementioned earphone drive circuit.One end of electric capacity is electrically connected to transistorized second end, and the other end ground connection of electric capacity.Detector then is electrically connected at transistorized the 3rd end.
Therefore in another earphone detecting circuit provided by the invention, the electric capacity in earphone detecting circuit can omit, the direct ground connection of the part that electrically connects mutually of above-mentioned transistorized second end and the 3rd resistance and first resistance and transistorized second end.Though so circuit-mode may show relatively poorly on resistance capacitance effect (RC effect), can save the shared volume of electric capacity, therefore can make integrated circuit more small and exquisite.
The present invention utilizes the transistor different on state characteristics that voltage difference is not had simultaneously between grid and leakage/source electrode, makes the earphone drive circuit that can't effectively detect the earphone Plug Action originally be added earphone detecting circuit.Whereby, the invention enables when the overall volume of earphone drive circuit is dwindled, still can possess the function of detecting earphone plug, and then make audio output device be kept the convenience of automatic switchover audio signal output pipeline.
Description of drawings
Fig. 1 is the circuit diagram of known employed earphone drive circuit and earphone detecting circuit;
Fig. 2 A is the circuit diagram of known employed another kind of earphone drive circuit;
Fig. 2 B is the circuit diagram of the employed earphone drive circuit of Fig. 2 A in conjunction with the earphone detecting circuit gained of Fig. 1;
Fig. 3 is the circuit diagram that earphone detecting circuit according to a preferred embodiment of the present invention combines with the earphone drive circuit;
Fig. 4 A for according to the preferred embodiment of Fig. 3 when earphone plugs, in the potential change curve chart that transistor gate detected;
Fig. 4 B for according to the preferred embodiment of Fig. 3 when earphone plugs, in the potential change curve chart that detector detected; And
Fig. 5 is the circuit diagram according to the earphone detecting circuit of another preferred embodiment of the present invention.
102,104,202-206,302-306: amplifier
106,108,346: electric capacity
110,112,210,212,310,312: audio signal transmission wire
114,214: ground wire
116,216: ground plate
118,120,218,220,318,320: contact
122,126,342,344: resistance
130,240,360: detector
132,312: the detecting circuit
124,322: sense terminal
230: earphone detecting circuit
300: transistor (P channel metal oxide semiconductor field effect transistor)
314: virtual grounding line 316: the virtual ground plate
330: source electrode 332: grid
334: drain electrode 336: base stage
Embodiment
In order to make those skilled in the art can understand technology contents of the present invention easily, earlier the earphone drive circuit shown in Fig. 2 A is done simple an introduction at this.In Fig. 2 A, the earphone drive circuit does not have actual ground connection, but with the voltage (V of virtual grounding line 214
Cc/ 2) be virtual ground voltage.Under this situation, suppose it is with as shown in Figure 1, by resistance 122 and 126 and the part formed of detecting circuit 132 come earphone detecting circuit 230 as herein, then its integrated circuit is just shown in Fig. 2 B.Note that in Fig. 2 B to have with the element of Fig. 1 or the identical numbering of Fig. 2 A and be similar to the element that has reference numeral among Fig. 1 or Fig. 2 A respectively.
Can learn that from Fig. 2 B when earphone did not insert, because the relation of Dc bias, the current potential of audio signal transmission wire 212 can be V
Cc/ 2, so detector 240 is exactly V by detecting circuit 132 resulting current potentials
Cc/ 2.Yet because digitized electronic circuit all is to use high electronegative potential when judging state, for instance, in the earphone drive circuit that the present invention is correlated with, general high potential is V
CcIt is neighbouring that (about 2.3V～3V), 0V～0.8V then is considered as electronegative potential.Therefore, the current potential that is detected when detector 240 is V
CcIn the time of/2 (being about about 1.5V), just can't judge whether earphone has been inserted in the earphone drive circuit actually.
This shows, knownly can't apply to really in the insert earphone drive circuit as Fig. 2 A in order to the circuit for detecting that whether inserts of detecting earphone.Therefore, inventor spy develops a kind of earphone detecting circuit of novelty to cooperate aforesaid insert earphone drive circuit.Must be noted that so the present invention is not that therefore and only restriction is used in the insert earphone drive circuit.
Please refer to Fig. 3, it is the circuit diagram that earphone detecting circuit according to a preferred embodiment of the present invention combines with the earphone drive circuit.Wherein, earphone detecting circuit is made up of transistor 300, resistance 340,342 and 344, electric capacity 346 and detector 360, and its sense terminal 322 is electrically connected on the audio signal transmission wire 312.In transistor 300, have first end 330, the second ends, 332, the three ends 334 and the 4th end 336.Wherein, first end 330 and the 4th end 336 electrically connect, and are electrically connected to operating voltage (V simultaneously
Cc).One end of resistance 340 is electrically connected to first end 330 of transistor 300, and its other end is electrically connected to second end 332 of transistor 300.One end of resistance 342 is electrically connected to the 3rd end 334 of transistor 300, and its other end ground connection.One end of resistance 344 is electrically connected to second end 332 of transistor 300, and its other end is electrically connected at sense terminal 322.One end of electric capacity 346 is electrically connected to second end 332 of transistor 300, and its other end ground connection.360 of detectors are electrically connected at the 3rd end 334 of transistor 300.
Wanting ben at this is, in order to separate the convenience of saying, this embodiment is to be the enforcement element of transistor 300 with P channel metal oxide semiconductor field effect transistor (P-channel MOSFET), therefore its four end points are respectively source electrodes 330, grid 332, drain electrode 334 and base stage 336, so this and unrestricted the present invention only can use P channel metal oxide semiconductor field effect transistor to implement, as long as any transistor has similar voltage turn-on characteristic, all can after making an amendment slightly, be applicable to this.
Below with the How It Works of detailed explanation earphone drive circuit, so in order to make those skilled in the art can clearer understanding content of the present invention, please in the lump with reference to Fig. 4 A and Fig. 4 B.Wherein, Fig. 4 A is the potential change curve chart that the P among Fig. 3 is ordered, and Fig. 4 B then is the detector 360 potential change curve chart that obtains of detecting.When earphone did not insert in the earphone drive circuit as yet, because sense terminal 322 is electrically connected at audio signal transmission wire 312, and audio signal transmission wire can the rough V that remains on when not having audio signal output
CcNear/2 the current potential, so the current potential of sense terminal 322 also is about V
Cc/ 2.And since the resistance value of resistance 340 much larger than the resistance value of resistance 344, so the current potential that P is ordered can be slightly larger than V approximately
Cc/ 2 (shown in Fig. 4 A).Under such situation, source electrode 330 will be slightly less than V with the potential difference of grid 332
Cc/ 2, but be enough to make transistor 300 conductings.Therefore, the current potential that detected of detector 360 can the rough V of approaching
Cc(shown in Fig. 4 B).
Next, in case earphone be inserted in the earphone drive circuit, and with sense terminal 322 top from the audio signal transmission wire 312 time (as the T among Fig. 4 A and Fig. 4 B
1Point), the P current potential of ordering can occur earlier changing.This is because for grid 332, when sense terminal 322 by the top after audio signal transmission wire 312, this section path has become the state of high impedance, so the P point can begin electric capacity 346 chargings, thereby the current potential that makes P order is more and more higher, up to V
CcNear just can stop (the T among Fig. 4 A
2The point).And bring up to V gradually at P point current potential
CcIn the time of neighbouring, transistor 300 can be closed, so detector 360 measured current potentials (or current potential of drain electrode end 334) can be reduced to 0 gradually (as the T among Fig. 4 B
2' point).In view of the above, detector 360 learns that earphone has been inserted in the earphone drive circuit, and this moment, audio signal just can send the user to by earphone drive circuit and earphone.
In time T
2To T
3Between, because earphone remains on the state that inserts in the earphone drive circuit, so the current potential that P is ordered can remain on V always
CcNear.Afterwards, earphone is at T
3Time point from the earphone drive circuit, remove, so sense terminal 322 can electrically connect with audio signal transmission wire 312 once more.Under such situation, because the current potential of sense terminal 322 approximates V
Cc/ 2 with the stack result of audio signal current potential, so the current potential that P is ordered can begin to fall downwards (as the T among Fig. 4 A
3To T
5), and because the resistance capacitance effect in the earphone detecting circuit, the second half section of the current potential that P order before stablizing can present a little fluctuation (as the T among Fig. 4 A
4To T
5).In addition, when P point current potential fell downwards, grid 332 can strengthen gradually with the potential difference of source electrode 330, and transistor 300 also can be therefore and conducting.So detector 360 measured current potentials (current potential of drain electrode 334) will rise near V gradually
CcTill.In view of the above, detector 360 just can be judged earphone and remove from the earphone drive circuit, thus audio signal just can change from other the place but not export via the earphone drive circuit.
In another preferred embodiment of the present invention, electric capacity 346 is omissible, and its detailed circuit as shown in Figure 5.Wherein, identical numbering is represented or similar elements identical with Fig. 3.Because operator scheme and Fig. 3 of as shown in Figure 5 earphone detecting circuit are similar, so in this not in addition repeat specification.What particularly point out a bit is, owing to lacked employed electric capacity 346 in Fig. 3 circuit, so its volume can further dwindle among Fig. 5, but its resistance-capacitance effect also can be a bit weaker simultaneously.
In sum, existing that advantage outline of the present invention is as follows. The present invention uses transistorized Voltage-on state characteristic can be so that can't add the circuit of Auto-Sensing headset plugging action originally The insert earphone drive circuit become and can detect headset plugging action. And this earphone detecting The volume of circuit is little, can not increase too many space cost concerning circuit originally.
Claims (9)
1, a kind of earphone detecting circuit is applicable to the Plug Action of detecting earphone in an earphone drive circuit, and this earphone drive circuit comprises a L channel end, a R channel end, and a virtual ground end and a sense terminal is characterized in that, this earphone detecting circuit comprises:
One transistor has one first end, one second end, one the 3rd end and one the 4th end, and this first end and the 4th end electrically connect, and are electrically connected to an operating voltage;
One first resistance, an end of this first resistance is electrically connected to this first end, and the other end of this first resistance is electrically connected to this second end;
One second resistance, an end of this second resistance is electrically connected to the 3rd end, and the other end ground connection of this second resistance, and wherein the resistance value of this first resistance is much larger than the resistance value of this second resistance;
One electric capacity, an end of this electric capacity is electrically connected to this second end, and the other end ground connection of this electric capacity;
One the 3rd resistance, an end of the 3rd resistance is electrically connected to this second end, and the other end of the 3rd resistance electrically connects this sense terminal; And
One detector is electrically connected at the 3rd end.
2, earphone detecting circuit as claimed in claim 1 is characterized in that, this transistor is a P channel metal oxide semiconductor field effect transistor.
3, earphone detecting circuit as claimed in claim 2 is characterized in that, this first end is a source electrode, and this second end is a grid, and the 3rd end is drain electrode, and the 4th end is a base stage.
4, a kind of earphone detecting circuit is applicable to the Plug Action of detecting earphone in an earphone drive circuit, and this earphone drive circuit comprises a L channel end, a R channel end, and a virtual ground end and a sense terminal is characterized in that, this earphone detecting circuit comprises:
One transistor has one first end, one second end, one the 3rd end and one the 4th end, and this first end and the 4th end electrically connect and are electrically connected to an operating voltage, the 3rd end ground connection;
One first resistance, this first resistance, one end is electrically connected to this first end, and the other end of this first resistance is electrically connected to this second end;
One second resistance, an end of this second resistance is electrically connected to the 3rd end, and the other end ground connection of this second resistance, and wherein the resistance value of this first resistance is much larger than the resistance value of this second resistance;
One the 3rd resistance, an end of the 3rd resistance is electrically connected to this second end, and the other end of the 3rd resistance electrically connects this sense terminal; And
One detector is electrically connected at the 3rd end.
5, earphone detecting circuit as claimed in claim 4 is characterized in that, this transistor is a P channel metal oxide semiconductor field effect transistor.
6, earphone detecting circuit as claimed in claim 5 is characterized in that, this first end is a source electrode, and this second end is a grid, and the 3rd end is drain electrode, and the 4th end is a base stage.
7, earphone detecting circuit as claimed in claim 4 is characterized in that, this circuit more comprises an electric capacity, and this transistorized this second end is electrically connected to an end of this electric capacity, again by the other end ground connection of this electric capacity.
8, earphone detecting circuit as claimed in claim 7 is characterized in that, this transistor is a P channel metal oxide semiconductor field effect transistor.
9, earphone detecting circuit as claimed in claim 8 is characterized in that, this first end is a source electrode, and this second end is a grid, and the 3rd end is drain electrode, and the 4th end is a base stage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02107551 CN1263347C (en) | 2002-03-15 | 2002-03-15 | Earphone detecting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02107551 CN1263347C (en) | 2002-03-15 | 2002-03-15 | Earphone detecting circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1446023A CN1446023A (en) | 2003-10-01 |
| CN1263347C true CN1263347C (en) | 2006-07-05 |
Family
ID=27811054
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02107551 Expired - Fee Related CN1263347C (en) | 2002-03-15 | 2002-03-15 | Earphone detecting circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1263347C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100594152B1 (en) * | 2004-12-28 | 2006-06-28 | 삼성전자주식회사 | Earphone jack deleting power-noise and the method |
| CN100368825C (en) * | 2005-12-31 | 2008-02-13 | 凌子龙 | Concealed earphone detector and detection method thereof |
-
2002
- 2002-03-15 CN CN 02107551 patent/CN1263347C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1446023A (en) | 2003-10-01 |
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| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20060705 Termination date: 20190315 |