CN1368834A - Differential anti-phase noise control system - Google Patents
Differential anti-phase noise control system Download PDFInfo
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- CN1368834A CN1368834A CN 01102324 CN01102324A CN1368834A CN 1368834 A CN1368834 A CN 1368834A CN 01102324 CN01102324 CN 01102324 CN 01102324 A CN01102324 A CN 01102324A CN 1368834 A CN1368834 A CN 1368834A
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Abstract
A differential reverse noise control system is provided with a microphone, wherein the microphone is connected to a front-end and equivalent amplifying circuit, the front-end and equivalent amplifying circuit is simultaneously connected to a phase amplifying circuit and a phase shifting amplifying circuit, the phase of the phase amplifying circuit and the phase shifting amplifying circuit form an angle of 90 degrees, the phase amplifying circuit and the phase shifting amplifying circuit are respectively connected to a variable resistor capable of adjusting vector gain and a power amplifier for amplifying signals, and finally, the phase amplifying circuit and the phase shifting amplifying circuit are respectively connected to different voice coils of a double-voice coil loudspeaker. The method can achieve the effect of changing the sound wave output phase, and can effectively control the accuracy of noise and point control so as to solve the problem of noise.
Description
The present invention relates to a kind of noise control system, relate in particular to a kind of effect that changes the sound wave output phase that reaches, can effectively control the accuracy of noise and system point, to solve the differential reverse noise control system of noise.
Along with the progress of society, though various sci-tech product brings people many facilities, yet also our surrounding enviroment are caused many destruction, as air pollution, noise pollution or the like.Wherein because noise pollution is directly to import in people's the brain by ear, the people can't being concentrated on, therefore how to eliminate the harm of noise to human body, to improve at home or the comfortableness of operational environment, is a big problem of existing efforts at environmental protection.
At present, commercially available noise abatement equipment embraces a wide spectrum of ideas, yet with regard to the mode of handling, mostly belong to the prophylactico-therapeutic measures of passivity, for example have at noise source and improve product structure or use shock-absorbing equipment etc., to reduce the active facture of its noise figure, also have at local space as the passive type facture with isolated external disturbance such as dress sound panel, sound-absorbing material, but these processing modes all can't effectively prevent the generation of noise.
So-called noise broadly comprises sound wave and ultrasonic wave, and sound wave then is direct hearing organ's generation effect to the mankind, and therefore, so-called noise general reference allows the people not feel well easily or easily disturbs the sound wave of mankind's activity.Since most noise be form with sound wave in the three dimensions transmission, so the effective method of control noise is just eliminated it when first moment of noise generation exactly, prevent that it from propagating in air.
In recent years, the theory that anti-phase sound wave can be offset the positive sound wave has obtained confirmation, the inventor once finished multinomial patent with this theory, invented patents such as novel No. 9600621 of No. 9601163.0, Germany novel No. 29515582 and France as No. 109936 patent in Taiwan, novel No. 3028291 patent of Japan, China invention ZL95220151.5 patent, Britain.Since and noise is a kind of sound wave, if use anti-phase sound wave to offset the principle of positive sound wave, reach the purpose that abates the noise, then the anti-phase noise killer of electronic type can apply in various places and the daily life in the near future widely.
Theory with regard to above-mentioned " positive and negative phase sound wave can support mutually ", the simple noise counter of one cover system mainly as shown in Figure 1, it is to collect noisy samples by a microphone A, through one group of preposition and equivalent amplifying circuit B the noisy samples signal is done suitable equivalence and amplification, then utilize phase inverter C with above-mentioned audio signal phasing back, and utilize power amplifier D that signal is amplified, with loud speaker E the anti-phase sound wave of anti-phase audio signal is sent at last, so that the anti-phase sound wave of the positive sound wave of noise and counter can repeal by implication, to abate the noise.But in practical application, as obtaining the effect of control of certain degree, then must overcome " the anti-phase sound wave that duplicates " and " the anti-phase sound wave of noise source relative position " inconsistent problem of phase place, because the anti-phase sound wave that duplicates through electronic circuit can be subjected to circuit " time delay coefficient " and loud speaker to cause the double influence of time delay because of physical factor, and the phase lag that " the anti-phase sound wave that duplicates " occur is in the phenomenon of " the anti-phase sound wave of noise source relative position " phase place.
Shown in Fig. 2 A, wherein the A curve is the noise sine wave; And A
-Curve is for offsetting the anti-phase relatively sine wave of A curve; C curve is the anti-phase sine wave that duplicates, and the sinusoidal wave At point of noise is offset vector and be should be A in theory
-The t point, however because above-mentioned different time delay phenomenon, the Ct point that causes duplicating lags behind A
-The t point, the result of this kind phase deviation can have influence on the effect that noise reduces, so hypothesis Ct falls behind A
-T has the phase differences of 90 degree, and when the At point is 90 when spending, its relative antiphase is changed to A
-T i.e. 90 degree, then vector
Vector
, this is the positive and negative vectorial counteracting pattern of theoretical ideal, shown in Fig. 2 B.But when At becomes Ct, then not only
With
Can't offset, can produce on the contrary
Offset vector, shown in Fig. 2 C.Like this, formerly desire to duplicate anti-phase sound wave and not only can't reach, can increase new noise on the contrary with the purpose of offset noise.
In view of this, in order effectively to bring into play the effect of electronic differential formula reverse noise control system, must critically control the output phase of anti-phase sound wave, the inventor is at the demand of above-mentioned counter noise, and actively seek the scheme that solves, through constantly making great efforts research and trial-production, successfully develop a kind of differential reverse noise control system that can effectively reduce noise finally, with effective solution noise problem.
Main purpose of the present invention is, a kind of differential reverse noise control system that reduces noise is provided, it mainly is to connect one to be used for the equivalent preposition and equivalent amplifying circuit that amplifies of fine signal on the microphone of negative your collection noisy samples, and preposition and equivalent amplifying circuit is connected to a phase place amplifying circuit and a phase shift amplifying circuit simultaneously, like this, can be with behind first group of voice coil loudspeaker voice coil importing from phase place amplifying circuit one group of vector variable-resistance in the double-coil loudspeaker with it, import the vectorial reciprocation of organizing separately of second group of voice coil loudspeaker voice coil again with from phase shift amplifying circuit and variable resistor thereof, reach the effect that changes the sound wave output phase, can effectively control the accuracy of noise and system point, to solve the problem of noise.
See also shown in Figure 3, the present invention mainly comprises microphone 10, preposition and equivalent amplifying circuit 20, phase place amplifying circuit, phase shift amplifying circuit, power amplifier and a double-coil loudspeaker 90, be used for guaranteeing to break through the accuracy of sound wave, to reach the purpose that reduces noise.
The objective of the invention is to realize by following technical scheme.
A kind of differential reverse noise control system, it is characterized in that, it has a microphone of being responsible for collecting noisy samples, microphone is connected to one and is used for the equivalent preposition and equivalent amplifying circuit that amplifies of small signal, this preposition and equivalent amplifying circuit is connected to a phase place amplifying circuit and a phase shift amplifying circuit simultaneously, wherein the phase place of phase place amplifying circuit and phase shift amplifying circuit is an angle of 90 degrees, and phase place amplifying circuit and phase shift amplifying circuit are connected to one respectively can adjust a variable resistor and the power amplifier with the signal amplification that vector gains, and is connected to respectively at last on the different voice coil loudspeaker voice coils of double-coil loudspeaker.
Purpose of the present invention can also further realize by following technical measures.
Aforesaid differential reverse noise control system, wherein this phase place amplifying circuit comprises a C
+In-phase amplification circuit and C
-See-saw circuit, both connect a switchable selector switch.
Aforesaid differential reverse noise control system, wherein this phase shift amplifying circuit comprises a C
+Δ phase shift amplifying circuit and C
-Δ phase shift amplifying circuit, both connect a switchable selector switch.
Purpose of the present invention also can be realized by following technical proposals.
A kind of differential reverse noise control system, it is characterized in that, it has a microphone of collecting noisy samples, this microphone is connected to one and is used for the equivalent preposition and equivalent amplifying circuit that amplifies of fine signal, preposition and equivalent amplifying circuit is connected to a phase place amplifying circuit and a phase shift amplifying circuit simultaneously, and wherein the phase place amplifying circuit includes a C
+In-phase amplification circuit and C
-See-saw circuit, the phase shift amplifying circuit then includes a C
+A Δ phase shift amplifying circuit and a C
-Δ phase shift amplifying circuit, the adjacent setting of this phase place amplifying circuit with the phase shift amplifying circuit, its phase place is an angle of 90 degrees mutually.
Again, C
+In-phase amplification circuit and C
-See-saw circuit is connected to a switchable selector switch jointly, this selector switch is connected to one in regular turn can adjust a variable resistor and the power amplifier with the signal amplification that vector gains, be connected at last on first group of voice coil loudspeaker voice coil of double-coil loudspeaker, and the C of phase shift amplifying circuit
+Δ phase shift amplifying circuit and C
-Δ phase shift amplifying circuit is connected to another selector switch, and this selector switch connects the power amplifier that the variable resistor and that can adjust vector gain amplifies signal in regular turn, and is last then be connected on second group of voice coil loudspeaker voice coil of double-coil loudspeaker.
The present invention can reach the effect that changes the sound wave output phase, can effectively control the accuracy of noise and system point, to solve the problem of noise.
For further understanding technology contents of the present invention, characteristics and effect, exemplify following preferred embodiment now, and conjunction with figs. is described in detail as follows:
Fig. 1 is a flow chart of commonly using noise counter system.
Fig. 2 A commonly uses noise and the right schematic diagram of counter acoustic ratio in the noise counter system.
Fig. 2 B is a schematic diagram of commonly using positive and negative vectorial counteracting pattern in the noise counter system.
Fig. 2 C commonly uses the pattern diagram that positive and negative vector can not be offset in the noise counter system.
Fig. 3 is the circuit arrangement schematic diagram of control system of the present invention.
Fig. 4 is the vectogram that double-coil loudspeaker output sound wave phase place of the present invention becomes miter angle.
Fig. 5 A is that the sound wave phase place of double-coil loudspeaker of the present invention output is to OC
+The vectogram that phase place is close.
Fig. 5 B is that the sound wave phase place of double-coil loudspeaker of the present invention output is to OC
+The vectogram that the Δ phase place is close.
Fig. 6 A is the schematic diagram that anti-phase sound wave phase place that the present invention adjusts output drops on first quartile.
Fig. 6 B is that the anti-phase sound wave phase place that the present invention adjusts output drops on four-quadrant schematic diagram.
Fig. 6 C is the schematic diagram that anti-phase sound wave phase place that the present invention adjusts output drops on second quadrant.
Fig. 6 D is the schematic diagram that anti-phase sound wave phase place that the present invention adjusts output drops on third quadrant.
Fig. 7 A-1 is that the present invention works as variable resistor 60 and transfers greatly, and the phase angle of variable resistor 65 output sound wave when turning down drops on the schematic diagram between 0～45 degree.
Fig. 7 A-2 is that the present invention works as variable resistor 60 and turns down, and variable resistor 65 transfers the phase angle of output sound wave when big to drop on schematic diagram between 45～90 degree.
Fig. 7 B-1 is that the present invention works as variable resistor 60 and transfers greatly, and the phase angle of variable resistor 65 output sound wave when turning down drops on the schematic diagram between 315～360 degree.
Fig. 7 B-2 is that the present invention works as variable resistor 60 and turns down, and variable resistor 65 transfers the phase angle of output sound wave when big to drop on schematic diagram between 270～315 degree.
Fig. 7 C-1 is that the present invention works as variable resistor 60 and transfers greatly, and the phase angle of variable resistor 65 output sound wave when turning down drops on the schematic diagram between 135～180 degree.
Fig. 7 C-2 is that the present invention works as variable resistor 60 and turns down, and variable resistor 65 transfers the phase angle of output sound wave when big to drop on schematic diagram between 90～135 degree.
Fig. 7 D-1 is that the present invention works as variable resistor 60 and transfers greatly, and the phase angle of variable resistor 65 output sound wave when turning down drops on the schematic diagram between 180～225 degree.
Fig. 7 D-2 is that the present invention works as variable resistor 60 and turns down, and variable resistor 65 transfers the phase angle of output sound wave when big to drop on schematic diagram between 225～270 degree.
Detailed structure of the present invention, see also shown in Figure 3, it has a microphone 10 of being responsible for collecting noisy samples, and microphone 10 is connected to a preposition and equivalent amplifying circuit 20, and wherein preposition and equivalent amplifying circuit 20 is used for the fine signal that microphone picks up being done the equivalence of appropriateness and amplifying.Again, preposition and equivalent amplifying circuit 20 is connected to phase place amplifying circuit and phase shift amplifying circuit simultaneously, makes the phase place amplifying circuit in parallel with the phase shift amplifying circuit, and wherein the phase place amplifying circuit comprises that one is the C at 0 degree angle
+In-phase amplification circuit 30 and one is the C at 180 degree angles
-See-saw circuit 35, and the phase shift amplifying circuit includes a C who is an angle of 90 degrees
+Δ phase shift amplifying circuit 40 and one is the C at 270 degree angles
-Δ phase shift amplifying circuit 45.
The C of this phase place amplifying circuit
+In-phase amplification circuit 30 and C
-See-saw circuit 35 is connected to the selector switch 50 that can select out of phase (for SW1), 50 of this selector switches are connected with one in regular turn can adjust a variable resistor 60 (for VR1) and the power amplifier 70 with the signal amplification (for AMP1) that vector gains, and is connected to a wherein voice coil loudspeaker voice coil 80 of double-coil loudspeaker 90 at last.And the C of phase shift amplifying circuit
+Δ phase shift amplifying circuit 40 and C
-45 of Δ phase shift amplifying circuits are connected to the selector switch 55 that can select different phase shifts (for SW2), selector switch 55 equally is connected to one in regular turn can adjust a variable resistor 65 (for VR2) and the power amplifier 75 with the signal amplification (being AMP2) that vector gains, and is connected to another voice coil loudspeaker voice coil 85 of double-coil loudspeaker 90 at last.
Like this, can be with after 80s from one group of voice coil loudspeaker voice coil in one group of vector input double-coil loudspeaker 90 of phase place amplifying circuit, variable resistor 60 and power amplifier 70, meeting and the vectorial reciprocation of organizing separately of importing second group of voice coil loudspeaker voice coil 85 from phase shift amplifying circuit, variable resistor 65 and power amplifier 75, reach the purpose that changes the sound wave output phase, group formation one can be adjusted the differential reverse noise control system of rp-wave phase place whereby.
Operation principle of the present invention please cooperate and consult shown in Fig. 4,5A, the 5B, as the load of first group of voice coil loudspeaker voice coil 80 C from 0 degree
+In-phase amplification circuit 30 (vector is represented with C1), then the sound wave of double-coil loudspeaker 90 relative outputs is 0 degree angle; Otherwise work as the C of the load of second group of voice coil loudspeaker voice coil 85 from an angle of 90 degrees
+During Δ phase shift amplifying circuit 40 (vector represent with C3), 90 of double-coil loudspeakers are the sound waves of output an angle of 90 degrees relatively, suppose that selector switch 50,55 selects C respectively
+In-phase amplification circuit 30 and C
+Δ phase shift amplifying circuit 40, and its vectorial C1, C3 all equal 1, then
This moment, the output phase of double-coil loudspeaker 90 became miter angle, as shown in Figure 4.And when we adjusted the gain of C1 and C3 vector by variable resistor 60,65, if variable resistor 60,65 is inversely proportional to when changing, then the phase place of double-coil loudspeaker 90 output sound waves also can present the phenomenon of wide-angle variations, wherein worked as
The time,
Phase place will produce to
The phenomenon that phase place is close is shown in Fig. 5 A; Otherwise, when
During Δ,
Phase place will produce to
The phenomenon that phase place is close is shown in Fig. 5 B.
By above-mentioned explanation, the phase place of in like manner provable double-coil loudspeaker 90 anti-phase sound wave outputs, can utilize the switching of selector switch 50,55, and the gain controlling that changes of variable resistor 60,65 inverse ratios, in each big quadrant, freely adjust the output phase of double-coil loudspeaker 90.The inventor does a simple declaration to the adjustment of selector switch 50,55 switchings and variable resistor 60,65, please cooperate and consult shown in Fig. 6,7, wherein C
+In-phase amplification circuit 30, C
-See-saw circuit 35, C
+Δ phase shift amplifying circuit 40 and C
-The vector of Δ phase shift amplifying circuit 45 is represented with C1, C2, C3 and C4 respectively.Select C respectively when selecting switch 50,55
+In-phase amplification circuit 30 and C
+During Δ phase shift amplifying circuit 40, then its output phase drops on first quartile (shown in Fig. 6 A), and transfers greatly when variable resistor 60, and variable resistor 65 is when turning down, and the output phase angle can drop on (as Fig. 7 A-1) between the 0-45 degree; Otherwise when variable resistor 60 is turned down, and variable resistor 65 is transferred when big, and then the output phase angle can drop on (shown in Fig. 7 A-2) between 45-90 degree angle.
In regular turn, when selecting switch 50,55 to select C respectively
+In-phase amplification circuit 30 and C
-During Δ phase shift amplifying circuit 45, then its output phase drops on four-quadrant (shown in Fig. 6 B), and transfers greatly when variable resistor 60, and variable resistor 65 is when turning down, and the output phase angle can drop on (shown in Fig. 7 B-1) between 315-360 degree angle; Otherwise turn down when variable resistor 60, and variable resistor 65 is transferred when big, then the output phase angle can drop on (shown in Fig. 7 B-2) between 270-315 degree angle.
Select C respectively when selecting switch 50,55
-See-saw circuit 35 and C
+During Δ phase shift amplifying circuit 40, then its output phase drops on second quadrant (Fig. 6 C), and when variable resistor 60 is transferred big, and variable resistor 65 is when turning down, the output phase angle can drop on (as Fig. 7 C-1) between 135-180 degree angle, otherwise turn down when variable resistor 60, and variable resistor 65 is transferred when big, then the output phase angle can be between 90-135 degree angle (shown in Fig. 7 C-2).
In addition when selecting switch 50,55 to select C respectively
-See-saw circuit 35 and C
+During Δ phase shift amplifying circuit 45, then its output phase drops on third quadrant (shown in Fig. 6 D), and transfers greatly when variable resistor 60, and variable resistor 65 is when turning down, and the output phase angle can drop on (shown in Fig. 7 D-1) between 180-225 degree angle; Otherwise turn down when variable resistor 60, and variable resistor 65 is transferred when big, then the output phase angle can drop on (shown in Fig. 7 D-2) between 225-270 degree angle.
It is as follows that the present invention adjusts the detail list of anti-phase sound wave phase place:
| ??SW1 | ??SW2 | Phase angle | The VR1 gain | The VR2 gain | Phase angle |
| ??C + | ??C +Δ | 0～90° | Greatly | Little | ??0～45° |
| Little | Greatly | ??45～90° | |||
| ??C + | ??C -Δ | 270～360° | Greatly | Little | ??315～360° |
| Little | Greatly | ??270～315° | |||
| ??C - | ??C +Δ | 90～180° | Greatly | Little | ??135～180° |
| Little | Greatly | ??90～135° | |||
| ??C - | ??C -Δ | 180～270° | Greatly | Little | ??180～225° |
| Little | Greatly | ??225～270° |
By the above-mentioned special design of the present invention, the user can be according to the difference of angle between anti-phase sound wave and noise sound wave, carry out the switching of above-mentioned selector switch 50,55 and the gain adjustment of variable resistor 60,65, make the load reciprocation of 90 liang of groups of input double-coil loudspeaker voice coil loudspeaker voice coil 80,85, and the output anti-phase sound wave identical with the noise sound wave reaches the purpose of offseting noise.The present invention can reach following effect at least:
1, breaks through the traditional circuit thinking, include the conventional loudspeakers that quality is difficult for controlling in electric-control system, improve the part level.
2, directly control the phase place of double-coil loudspeaker 90 sound waves output, need not consider the interference that the electronic apparatus and the physics equal error factor produce.
3, the differential gear that has comprehensive phase modulation function can more accurate control noise counter point.
4, do not need complicated correcting circuit, only need several parts of controlling easily, can replace accurate expensive again rectifying an instrument and equipment.
In sum, the present invention can effectively solve the problem that existing noise counter point is difficult for control, have above-mentioned advantage and practical value simultaneously, therefore the present invention one highly utilizes the creationary design of having of law of nature, and in identical technical field, do not see identical or approximate product public use, meet the important document of patent of invention, so file an application in accordance with the law.
The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, every foundation technical spirit of the present invention all still belongs in the scope of technical solution of the present invention any simple modification, equivalent variations and modification that above embodiment did.
Claims (4)
1, a kind of differential reverse noise control system, it is characterized in that, it has a microphone of being responsible for collecting noisy samples, microphone is connected to one and is used for the equivalent preposition and equivalent amplifying circuit that amplifies of small signal, this preposition and equivalent amplifying circuit is connected to a phase place amplifying circuit and a phase shift amplifying circuit simultaneously, wherein the phase place of phase place amplifying circuit and phase shift amplifying circuit is an angle of 90 degrees, and phase place amplifying circuit and phase shift amplifying circuit are connected to one respectively can adjust a variable resistor and the power amplifier with the signal amplification that vector gains, and is connected to respectively at last on the different voice coil loudspeaker voice coils of double-coil loudspeaker.
2, differential reverse noise control system according to claim 1 is characterized in that, described phase place amplifying circuit comprises a C
+In-phase amplification circuit and C
-See-saw circuit, both connect a switchable selector switch.
3, differential reverse noise control system according to claim 1 is characterized in that, described phase shift amplifying circuit comprises a C
+Δ phase shift amplifying circuit and C
-Δ phase shift amplifying circuit, both connect a switchable selector switch.
4, a kind of differential reverse noise control system, it is characterized in that, it has a microphone of collecting noisy samples, this microphone is connected to one and is used for the equivalent preposition and equivalent amplifying circuit that amplifies of fine signal, preposition and equivalent amplifying circuit is connected to a phase place amplifying circuit and a phase shift amplifying circuit simultaneously, and wherein the phase place amplifying circuit includes a C
+In-phase amplification circuit and C
-See-saw circuit, the phase shift amplifying circuit then includes a C
+A Δ phase shift amplifying circuit and a C
-Δ phase shift amplifying circuit, the adjacent setting of this phase place amplifying circuit with the phase shift amplifying circuit, its phase place is an angle of 90 degrees mutually;
Again, C
+In-phase amplification circuit and C
-See-saw circuit is connected to a switchable selector switch jointly, this selector switch is connected to one in regular turn can adjust a variable resistor and the power amplifier with the signal amplification that vector gains, be connected at last on first group of voice coil loudspeaker voice coil of double-coil loudspeaker, and the C of phase shift amplifying circuit
+Δ phase shift amplifying circuit and C
-Δ phase shift amplifying circuit is connected to another selector switch, and this selector switch connects the power amplifier that the variable resistor and that can adjust vector gain amplifies signal in regular turn, and is last then be connected on second group of voice coil loudspeaker voice coil of double-coil loudspeaker.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 01102324 CN1368834A (en) | 2001-02-02 | 2001-02-02 | Differential anti-phase noise control system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 01102324 CN1368834A (en) | 2001-02-02 | 2001-02-02 | Differential anti-phase noise control system |
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| Publication Number | Publication Date |
|---|---|
| CN1368834A true CN1368834A (en) | 2002-09-11 |
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ID=4652640
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|---|---|---|---|
| CN 01102324 Pending CN1368834A (en) | 2001-02-02 | 2001-02-02 | Differential anti-phase noise control system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100380311C (en) * | 2004-12-28 | 2008-04-09 | 三星电子株式会社 | Headphone jack for eliminating power noise in mobile communication terminal and method of operation thereof |
| CN101385385B (en) * | 2006-04-01 | 2013-03-06 | 沃福森微电子股份有限公司 | Environmental noise reduction control system |
| CN107809693A (en) * | 2017-11-20 | 2018-03-16 | 中山奥凯华泰电子有限公司 | Double voice coil earphone |
-
2001
- 2001-02-02 CN CN 01102324 patent/CN1368834A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100380311C (en) * | 2004-12-28 | 2008-04-09 | 三星电子株式会社 | Headphone jack for eliminating power noise in mobile communication terminal and method of operation thereof |
| CN101385385B (en) * | 2006-04-01 | 2013-03-06 | 沃福森微电子股份有限公司 | Environmental noise reduction control system |
| CN107809693A (en) * | 2017-11-20 | 2018-03-16 | 中山奥凯华泰电子有限公司 | Double voice coil earphone |
| CN107809693B (en) * | 2017-11-20 | 2019-12-17 | 中山奥凯华泰电子有限公司 | Double-voice-coil earphone |
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