CN201153249Y - Silencing circuit for start-up and close-down, audio and video apparatus having the circuit - Google Patents
Silencing circuit for start-up and close-down, audio and video apparatus having the circuit Download PDFInfo
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- CN201153249Y CN201153249Y CNU2008200169359U CN200820016935U CN201153249Y CN 201153249 Y CN201153249 Y CN 201153249Y CN U2008200169359 U CNU2008200169359 U CN U2008200169359U CN 200820016935 U CN200820016935 U CN 200820016935U CN 201153249 Y CN201153249 Y CN 201153249Y
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Abstract
The utility model discloses an ON/OFF mute circuit and audio and video equipment having the circuit, comprising a DC power, PNP-type triodes, storage capacitors and an NPN-type triode. On one aspect, the base electrode of the PNP-type triode is grounded through a first storage capacitor and is connected with the DC power on the other aspect; on one aspect, a transmitting electrode is connected with a second storage capacitor and is connected with the DC power through a first switch diode on the other aspect; the collecting electrode, on one aspect, is connected with a first NPN-type triode, the collecting electrode of which is connected with the right channel of the audio output circuit as a first output end and is connected with a second NPN-type triode on the other aspect; the collecting electrode of the second NPN-type triode is connected with the left channel of the audio output circuit as a second output end. The circuit in the utility model realizes the control of the ON/OFF mute and has simple structure and low cost.
Description
Technical field
The utility model belongs to mute circuit, specifically, relates to a kind of mute circuit for open and close of audio ﹠ video equipment.
Background technology
Household appliances because the effect of current impulse produces bigger plosive, form on-off noise when start or shutdown.Along with improving constantly of consumer spending level, people are more and more higher to the soften requirement of sound accompaniment, and on-off noise becomes a problem must considering in the circuit design.Noise when the audio frequency DAC chip of employing better performances can reduce switching on and shutting down, but this can not eliminate the noise of switching on and shutting down fully, comes perfect so need increase mute circuit in system.At present mute circuit has multiple implementation, but circuit structure relative complex, cost height, the mute circuit for open and close that the utility model provides can be applicable to audio ﹠ video equipments such as set-top box, television set, and circuit structure is simple, cost is low.
Summary of the invention
The utility model has designed a kind of mute circuit for open and close that can be applicable to audio ﹠ video equipment, comprises DC power supply, positive-negative-positive triode, storage capacitor, NPN type triode.The input of wherein said mute circuit for open and close connects DC power supply, on when conducting DC power supply storage capacitor is charged; Storage capacitor discharges electric charge at the back store charge that powers on during the shutdown power down; Two outputs of described mute circuit for open and close connect the left and right acoustic channels of audio output circuit respectively.
In order to solve mute circuit for open and close complex structure in the prior art, problem that cost is high, the utility model provides a kind of novel mute circuit for open and close.Wherein, described mute circuit comprises the positive-negative-positive triode, and the base stage of described positive-negative-positive triode connects DC power supply through first resistance on the other hand on the one hand through the first storage capacitor ground connection; Emitter connects DC power supply through first switching diode on the one hand, on the other hand through the second storage capacitor ground connection; Collector electrode is connected to the audio output circuit R channel through a NPN type triode on the one hand, is connected to the audio output circuit L channel through the 2nd NPN type triode on the other hand.
When being implemented in power supply power-fail, the electric charge that is connected in first storage capacitor on the positive-negative-positive transistor base can be fallen by timely bleed off, between described DC power supply and positive-negative-positive transistor base, be connected with the parallel branch of first resistance and bleed off diode, the negative electrode of described bleed off diode connects described DC power supply, and anode connects the base stage of positive-negative-positive triode.When start, DC power supply is to first storage capacitor and the charging of second storage capacitor; During shutdown, first storage capacitor discharges rapidly to the dc power supply terminal that is equivalent to be shorted to ground through the bleed off diode.
Two outputs of mute circuit for open and close link to each other with the final output of audio signal output circuit left and right acoustic channels respectively.When the output of described mute circuit for open and close was low level, the left and right acoustic channels output voltage was 0, and output current also is 0, and external equipment does not have electric current to pass through, and this just reaches quiet purpose; When a NPN type triode and the 2nd NPN type triode were in by state, mute circuit for open and close did not act on audio output circuit, and audio signal is normally exported.
Compared with prior art, accurately quiet when the utility model has been realized switching on and shutting down by simple circuit configuration efficiently solves the problem of audio ﹠ video equipment switching on and shutting down moment noise, satisfied consumer's appreciation demand.
Description of drawings
Fig. 1 is the structured flowchart of the utility model mute circuit for open and close preferred embodiment;
Fig. 2 is the schematic diagram of the utility model mute circuit for open and close preferred embodiment.
Embodiment
Below in conjunction with the drawings and specific embodiments the utility model is described in further details, the audio ﹠ video equipment of selecting for use in this specific embodiment is a set-top box.
As shown in Figure 1, digital audio and video signals is sent to amplifying circuit 101 after D/A change-over circuit 100 is converted to left and right two-way simulated audio signal, the output terminals A U_R of mute circuit for open and close 103, AU_L are connected with R channel, the L channel of audio output circuit 104 respectively.When set-top box 105 switching on and shutting down, output terminals A U_R, the AU_L of mute circuit for open and close 103 are output as low level, at this moment the R channel of audio output circuit 104, L channel output voltage are 0, then output current is 0, external equipment does not have electric current to pass through, thus quiet purpose when having realized switching on and shutting down.
After set-top box 105 start is finished, enter normal condition, this moment mute circuit for open and close 103 two outputs in by state, audio signal through audio output circuit 104 normal transmission to output interface 102.
As shown in Figure 2, mute circuit for open and close 103 comprises a positive-negative-positive triode VT401, the base stage of described positive-negative-positive triode VT401 is connected with the first free-wheeling diode C413 through second resistance R 420 on the one hand, the other end ground connection of the first free-wheeling diode C413, parallel branch and inductance B403 through first resistance R 410 and bleed off diode VD402 is connected DC power supply on the other hand, particularly, the negative electrode of described bleed off diode is connected with DC power supply through inductance B403, and the anode of bleed off diode VD402 is connected with the base stage of positive-negative-positive triode through second resistance R 420; Its emitter is connected with the second storage capacitor C414 through the 3rd resistance R 417 on the one hand, the other end ground connection of the second free-wheeling diode C414, link to each other with DC power supply through switching diode VD402, inductance B403 on the other hand, particularly, the anode of switching diode VD402 is connected with DC power supply through inductance B403, and the negative electrode of switching diode VD402 is connected with the emitter of positive-negative-positive triode VT401; Collector electrode is connected with a NPN type triode VT402 through the 4th resistance R 418, second switch diode VD403 on the one hand, be connected with the 2nd NPN type triode VT403 through the 5th resistance R 419, the 3rd switching diode VD404 on the other hand, a NPN type transistor base is connected with the negative electrode of diode VD403 particularly, transmitting terminal ground connection, collector electrode is as the first output terminals A U_R of mute circuit for open and close, the 2nd NPN type transistor base is connected with the negative electrode of diode VD404, transmitting terminal ground connection, collector electrode is as the second output terminals A U_L of mute circuit for open and close.
The concrete course of work: in the moment that start powers on, the current potential of V1 is 12V, DC power supply is given the first storage capacitor C413 charging through inductance B403, first resistance R 410 on the one hand, and on the other hand through switching diode VD402, the 3rd resistance R 417 is given the second storage capacitor C414 charging.Characteristic according to the RC circuit: V2=U (1-e
-t/RC), the potential difference of V1 and V2 is greater than 0.7 volt, at this moment positive-negative-positive triode VT401 saturation conduction, V3 is a high potential, makes win NPN type triode VT402 and the 2nd NPN type triode VT403 be in the saturation conduction state, and output terminals A U_R and AU_L are low level, the R channel of the audio output circuit that is connected with them, L channel output voltage are 0, then output current is 0, and external equipment does not have electric current to pass through, thereby has realized the purpose of turn-on muting.
The potential difference that is charged to V1 and V2 as the first storage capacitor C413 is during less than 0.7V, positive-negative-positive triode VT401 is in by state, this moment, the one NPN type triode VT402 and the 2nd NPN type triode VT403 were in by state, and audio signal is normally exported through audio output circuit.
When shutdown, DC power supply is equivalent to be shorted to ground, the first storage capacitor C413 rushes down rapidly by bleed off diode VD402, switching diode VD402 is in the reverse operation state, make V1 keep high potential, this moment positive-negative-positive triode VT401 saturation conduction, V3 is a high potential, so a NPN type triode VT402 and the 2nd NPN type triode VT403 saturation conduction, the output terminals A U_R of mute circuit, AU_L is output as low level, the L channel of the audio output circuit that is attached thereto, the output voltage of R channel is 0, and output current is 0, thereby has realized the quiet purpose of shutting down.
Accurately quiet when the utility model has been realized the audio ﹠ video equipment switching on and shutting down by adopting above-mentioned simple circuit configuration efficiently solves the problem of audio ﹠ video equipment switching on and shutting down moment noise, satisfied consumer's appreciation demand.Certainly; above-mentioned explanation is not to be to restriction of the present utility model; the utility model also is not limited in above-mentioned giving an example, and variation, remodeling, interpolation or replacement that those skilled in the art are made in essential scope of the present utility model also should belong to protection range of the present utility model.
Claims (10)
1. mute circuit for open and close, comprise DC power supply, it is characterized in that, described mute circuit for open and close also comprises the positive-negative-positive triode, storage capacitor, NPN type triode, the base stage of described positive-negative-positive triode is on the one hand through the first storage capacitor ground connection, connect DC power supply on the other hand, emitter is on the one hand through the second storage capacitor ground connection, connect DC power supply on the other hand, collector electrode connects a NPN type triode on the one hand, the collector electrode of a described NPN type triode links to each other with the audio output circuit R channel as first output, connect the 2nd NPN type triode on the other hand, the collector electrode of described the 2nd NPN type triode links to each other with the audio output circuit L channel as second output.
2. mute circuit for open and close according to claim 1, it is characterized in that, be connected with the parallel branch of first resistance and bleed off diode between described DC power supply and the positive-negative-positive transistor base, the negative electrode of described bleed off diode connects DC power supply through inductance, and anode connects the base stage of positive-negative-positive triode through second resistance.
3. mute circuit for open and close according to claim 1, it is characterized in that, the emitter of described positive-negative-positive triode connects the first switching diode negative electrode on the other hand on the one hand through the 3rd resistance, the second storage capacitor ground connection, and the anode of described switching diode is connected with DC power supply through inductance.
4. mute circuit for open and close according to claim 1, it is characterized in that, a described NPN type transistor base connects the negative electrode of second switch diode, the anode of described second switch diode connects the collector electrode of positive-negative-positive triode through the 4th resistance, a described NPN type transistor emitter ground connection, collector electrode is as first output of mute circuit for open and close.
5. mute circuit for open and close according to claim 1, it is characterized in that, described the 2nd NPN type transistor base connects the negative electrode of the 3rd switching diode, the anode of described the 3rd switching diode connects the collector electrode of positive-negative-positive triode through the 5th resistance, the 2nd NPN type transistor emitter ground connection, collector electrode is as second output of mute circuit for open and close.
6. one kind has the described audio ﹠ video equipment of claim 1, comprise DC power supply, it is characterized in that, described mute circuit for open and close also comprises the positive-negative-positive triode, storage capacitor, NPN type triode, the base stage of described positive-negative-positive triode is on the one hand through the first storage capacitor ground connection, connect DC power supply on the other hand, emitter is on the one hand through the second storage capacitor ground connection, connect DC power supply on the other hand, collector electrode connects a NPN type triode on the one hand, the collector electrode of a described NPN type triode links to each other with the audio output circuit R channel as first output, connect the 2nd NPN type triode on the other hand, the collector electrode of described the 2nd NPN type triode links to each other with the audio output circuit L channel as second output.
7. audio ﹠ video equipment according to claim 6, it is characterized in that, be connected with the parallel branch of first resistance and bleed off diode between described DC power supply and the positive-negative-positive transistor base, the negative electrode of described bleed off diode connects DC power supply through inductance, and anode connects the base stage of positive-negative-positive triode through second resistance.
8. audio ﹠ video equipment according to claim 6, it is characterized in that, the emitter of described positive-negative-positive triode connects the first switching diode negative electrode on the other hand on the one hand through the 3rd resistance, the second storage capacitor ground connection, and the anode of described switching diode is connected with DC power supply through inductance.
9. audio ﹠ video equipment according to claim 6, it is characterized in that, a described NPN type transistor base connects the negative electrode of second switch diode, the anode of described second switch diode connects the collector electrode of positive-negative-positive triode through the 4th resistance, a described NPN type transistor emitter ground connection, collector electrode is as first output of mute circuit for open and close.
10. audio ﹠ video equipment according to claim 6, it is characterized in that, described the 2nd NPN type transistor base connects the negative electrode of the 3rd switching diode, the anode of described the 3rd switching diode connects the collector electrode of positive-negative-positive triode through the 5th resistance, the 2nd NPN type transistor emitter ground connection, collector electrode is as second output of mute circuit for open and close.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008200169359U CN201153249Y (en) | 2008-01-21 | 2008-01-21 | Silencing circuit for start-up and close-down, audio and video apparatus having the circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008200169359U CN201153249Y (en) | 2008-01-21 | 2008-01-21 | Silencing circuit for start-up and close-down, audio and video apparatus having the circuit |
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| Publication Number | Publication Date |
|---|---|
| CN201153249Y true CN201153249Y (en) | 2008-11-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2008200169359U Expired - Fee Related CN201153249Y (en) | 2008-01-21 | 2008-01-21 | Silencing circuit for start-up and close-down, audio and video apparatus having the circuit |
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|---|---|
| CN (1) | CN201153249Y (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102905212A (en) * | 2011-07-25 | 2013-01-30 | 冠捷投资有限公司 | Anti-sonic boom display device and audio signal processing device |
| CN104238668A (en) * | 2014-08-29 | 2014-12-24 | 山东超越数控电子有限公司 | Method for eliminating computer boosting and shutdown noise |
| WO2018045770A1 (en) * | 2016-09-12 | 2018-03-15 | 京东方科技集团股份有限公司 | Control circuit, control method and electronic device |
-
2008
- 2008-01-21 CN CNU2008200169359U patent/CN201153249Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102905212A (en) * | 2011-07-25 | 2013-01-30 | 冠捷投资有限公司 | Anti-sonic boom display device and audio signal processing device |
| CN104238668A (en) * | 2014-08-29 | 2014-12-24 | 山东超越数控电子有限公司 | Method for eliminating computer boosting and shutdown noise |
| WO2018045770A1 (en) * | 2016-09-12 | 2018-03-15 | 京东方科技集团股份有限公司 | Control circuit, control method and electronic device |
| US10298180B2 (en) | 2016-09-12 | 2019-05-21 | Boe Technology Group Co., Ltd. | Control circuit, control method, and electronic device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20081119 Termination date: 20120121 |