CN203840514U - Active noise abatement circuit for mobile phone - Google Patents

Active noise abatement circuit for mobile phone Download PDF

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Publication number
CN203840514U
CN203840514U CN201420216523.5U CN201420216523U CN203840514U CN 203840514 U CN203840514 U CN 203840514U CN 201420216523 U CN201420216523 U CN 201420216523U CN 203840514 U CN203840514 U CN 203840514U
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CN
China
Prior art keywords
microphone
filter
earphone
circuit
active noise
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
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CN201420216523.5U
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Chinese (zh)
Inventor
甘国华
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ANPAC SEMICONDUCTOR Ltd
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ANPAC SEMICONDUCTOR Ltd
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Priority to CN201420216523.5U priority Critical patent/CN203840514U/en
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Publication of CN203840514U publication Critical patent/CN203840514U/en
Expired - Fee Related legal-status Critical Current
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Abstract

The utility model discloses an active noise abatement circuit for a mobile phone. After the ambient noise signals of each sound channel are collected by a microphone of an earphone, the ambient noise signals are processed by at least two microphone amplification filter circuits, the processed noise signals and audio signals enter into a mixer to be mixed together, and then are transmitted to a loudspeaker after being amplified by an amplifier, and each microphone amplification filter circuit includes a variable gain microphone amplifier and a filter. The active noise abatement circuit can improve the noise abatement effect and has the advantages of low cost, small earphone size, low power consumption, and batch production.

Description

A kind of active noise for earphone is eliminated circuit
Technical field
The utility model relates to a kind of active noise for earphone and eliminates circuit, belongs to audio frequency apparatus noise reduction technology field.
Background technology
It is for preventing that unnecessary sound wave from arriving hearer's ear-drum that noise is eliminated.Active noise is eliminated (Active Noise Cancellation, ANC) technology adopts electronically to produce sound waves identical with ambient noise amplitude but phase phasic difference 180 degree, by destructive interference (destructive interference), to eliminate ambient noise.General feed forward type, reaction type or hybrid (feed forward type+reaction type) circuit of using realized.
Figure 16 is that active noise technology for eliminating is applied in the typical circuit on feed forward type or reaction type earphone.After the ambient noise signal of each sound channel is collected by microphone, through 1 microphone filtering and amplifying circuit, process, the noise signal after processing enters frequency mixer together with audio signal mixes, then imports loud speaker into after amplifier amplifies; This microphone filtering and amplifying circuit comprises variable gain amplifier of microphone and filter.Its noise eradicating efficacy is the acoustic response that depends on very much earphone, if particularly earphone is lower at the sound pressure level (sound pressure level) of some frequency range, the sound wave of the antiphase being produced by it so only can be eliminated the component environment noise of this frequency range, thereby has affected noise eradicating efficacy.As shown in figure 17, earphone differs 6dB at the sound pressure level at 50Hz frequency place and 500Hz frequency place.As shown in figure 18, the antiphase sound wave wave amplitude that 50Hz frequency place produces is 100% of ambient noise, therefore can eliminate whole noises; As shown in figure 19, the antiphase sound wave wave amplitude that 500Hz frequency place produces is 50% of ambient noise, therefore only can eliminate partial noise.As can be seen here, overall noise eradicating efficacy may be high in some frequency range, but low in some frequency range.
In addition, typical feed forward type or reaction type earphone, generally can only produce the noise eradicating efficacy (as shown in figure 11) of the most about 20 decibels.For being brought up to, noise eradicating efficacy is greater than 30 decibels, need to adopt hybrid (feed forward type+reaction type) configuration, but it needs two microphones, will increase component count, product shape size and cost like this, and no matter adopt numeral (DSP) still to simulate noise reduction technology, all need higher power dissipation.
Utility model content
The purpose of this utility model is, provides a kind of active noise for earphone to eliminate circuit, can improve noise eradicating efficacy, and have advantages of cost-saving, earphone size is little, power consumption is low, be suitable for producing in enormous quantities.
The technical solution of the utility model: a kind of active noise for earphone is eliminated circuit, comprise the microphone, at least 2 microphone filtering and amplifying circuits, frequency mixer, amplifier and the loud speakers that connect in turn, each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter; The ambient noise signal of each sound channel is processed through microphone filtering and amplifying circuit respectively after being collected by the microphone of earphone, and the noise signal after process on each road enters frequency mixer together with audio signal mixes, then amplifies through amplifier, imports loud speaker into; Wherein, variable gain amplifier of microphone is for adjusting the big or small of microphone signal, can realize the optimizing level of homophase not or inversion signal.
Preferably, the described active noise for earphone is eliminated circuit and is comprised microphone, 2 microphone filtering and amplifying circuits, frequency mixer, amplifier and the loud speakers that connect in turn, and each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter; After the ambient noise signal of each sound channel is collected by the microphone of earphone, through 2 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer together with audio signal mixes, then amplifies through amplifier, imports loud speaker into.
The aforesaid active noise for earphone is eliminated circuit, between microphone and microphone filtering and amplifying circuit, preamplifier is set; Preamplifier can be supported the signal path of a plurality of amplifier of microphone and filter bank, realizes the modulation of a plurality of frequency ranges, to keep the integrality of microphone signal.
The aforesaid active noise for earphone is eliminated circuit, can adopt lower-cost buffer to replace preamplifier, between microphone and microphone filtering and amplifying circuit, buffer is set, the voltage gain of buffer is one, voltage that can not amplification input signal, electric current that can only amplification input signal.
The aforesaid active noise for earphone is eliminated circuit, and filter is arranged between variable gain amplifier of microphone and frequency mixer.
The aforesaid active noise for earphone is eliminated circuit, and filter is arranged between microphone and variable gain amplifier of microphone.
The aforesaid active noise for earphone is eliminated circuit, filter for band is logical, high pass or low pass filter, to select to need anti-phase signal frequency range.
The aforesaid active noise for earphone is eliminated circuit, and filter is firstorder filter, second order filter Ge multi-stage filter.
The aforesaid active noise for earphone is eliminated circuit, and described earphone is headphone or In-Ear Headphones.
Compared with prior art, microphone noise signal path of the present utility model (being microphone filtering and amplifying circuit) adopts the combinational circuits of 2 above variable gain amplifier of microphone+filters, makes the gain amplifier of different stage be applied to the different frequency range of microphone signal.That is to say, if earphone is high at the acoustic response of low-frequency range, and it is low at the acoustic response of medium frequency section, after application the utility model, can apply low-level gain amplifier to low-frequency range, and Mid Frequency is applied to high-caliber gain amplifier, the acoustic response that has compensated earphone is inhomogeneous different frequency range; If microphone is low in the sensitivity of low-frequency range, and highly sensitive in high-frequency section, after application the utility model, can be applied high-caliber gain amplifier to low-frequency range, and high band applied to low-level gain amplifier, compensated inhomogeneous at different frequency range of sensitivity of microphone.Each filter tuner process only need to be looked after a narrow frequency range, can complete more easily, quickly tuning process, thereby all reach high-caliber noise eradicating efficacy in all frequency ranges.
The utility model, without adopting hybrid circuit (headset ear shell is inside and outside a microphone is respectively set), only need arrange a microphone (being feed forward type or reaction type), and its noise eradicating efficacy is with hybrid-type suitable, even better.
Along with Portable audio/video equipment, if the appearance of MP3, mobile phone, music player, portable electronic device (PMP), notebook computer, net book computer etc. is with universal, wear-type and In-Ear Headphones have become considerable electronic equipment accessory in people's daily life.Because the noisy environment in public place can reduce people greatly, utilize earphone to receive the accuracy of acoustic information, so people pay close attention to the aspects such as the noise elimination function, size, power consumption of earphone more.Active noise described in the utility model is eliminated circuit and be can be applicable to (comprise wired, wireless headset) in various earphones, and the earphone of applying this circuit has low cost of manufacture, size is little, lightweight, power consumption is low, be suitable for the advantages such as production in enormous quantities.
Accompanying drawing explanation
Fig. 1, Fig. 2, Fig. 3 are that active noise of the present utility model is eliminated circuit diagram;
Fig. 4 is that the active noise of embodiment 1 is eliminated circuit diagram;
Fig. 5 is that the active noise of embodiment 2 is eliminated circuit diagram;
Fig. 6 is that the active noise of embodiment 3 is eliminated circuit diagram;
Fig. 7 is that the active noise of embodiment 4 is eliminated circuit diagram;
Fig. 8 is that the active noise of embodiment 5 is eliminated circuit diagram;
Fig. 9 is that the active noise of embodiment 6 is eliminated circuit diagram;
Figure 10 is the filter circuit frequency response chart of prior art;
Figure 11 is the active noise eradicating efficacy figure of prior art;
Figure 12 is the filter circuit frequency response chart of embodiment 1, embodiment 2, embodiment 3;
Figure 13 is the active noise eradicating efficacy figure of embodiment 1, embodiment 2, embodiment 3;
Figure 14 is the filter circuit frequency response chart of embodiment 4, embodiment 5, embodiment 6;
Figure 15 is the active noise eradicating efficacy figure of embodiment 4, embodiment 5, embodiment 6;
Figure 16 is that the active noise of prior art is eliminated circuit diagram;
Figure 17 is headphone acoustic response diagram;
Figure 18, Figure 19 are respectively that the noise at 50Hz, 500Hz frequency place is eliminated schematic diagram.
Embodiment
Below in conjunction with drawings and Examples, the utility model is further described.
Embodiment 1 of the present utility model: a kind of active noise for earphone is eliminated circuit, as shown in Figure 4, after the ambient noise signal of each sound channel is collected by microphone, through 2 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter, and filter is arranged between variable gain amplifier of microphone and frequency mixer; Between microphone and microphone filtering and amplifying circuit, preamplifier is set.
Embodiment 2 of the present utility model: a kind of active noise for earphone is eliminated circuit, as shown in Figure 5, after the ambient noise signal of each sound channel is collected by microphone, through 2 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter, between microphone and microphone filtering and amplifying circuit, preamplifier is set, and filter is arranged between preamplifier and variable gain amplifier of microphone.
Embodiment 3 of the present utility model: a kind of active noise for earphone is eliminated circuit, as shown in Figure 6, after the ambient noise signal of each sound channel is collected by microphone, through 2 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter, between microphone and microphone filtering and amplifying circuit, preamplifier is set, filter is arranged between preamplifier and variable gain amplifier of microphone and between variable gain amplifier of microphone and frequency mixer.
Embodiment 4 of the present utility model: a kind of active noise for earphone is eliminated circuit, as shown in Figure 7, after the ambient noise signal of each sound channel is collected by microphone, through 3 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter, and filter is arranged between variable gain amplifier of microphone and frequency mixer; Between microphone and microphone filtering and amplifying circuit, preamplifier is set.
Embodiment 5 of the present utility model: a kind of active noise for earphone is eliminated circuit, as shown in Figure 8, after the ambient noise signal of each sound channel is collected by microphone, through 3 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter, between microphone and microphone filtering and amplifying circuit, preamplifier is set, and filter is arranged between preamplifier and variable gain amplifier of microphone.
Embodiment 6 of the present utility model: a kind of active noise for earphone is eliminated circuit, as shown in Figure 9, after the ambient noise signal of each sound channel is collected by microphone, through 3 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter, between microphone and microphone filtering and amplifying circuit, preamplifier is set, filter is arranged between preamplifier and variable gain amplifier of microphone and between variable gain amplifier of microphone and frequency mixer.
Except the microphone noise signal path on 2 tunnels shown in above-described embodiment, 3 tunnels, can also adopt microphone noise signal paths more than 3 tunnels, as shown in Figure 1, Figure 2, Figure 3 shows (N>3 in figure).
In above-described embodiment, available buffer replaces preamplifier, between microphone and microphone filtering and amplifying circuit, buffer is set; Filter is can select tape logical, high pass or low pass filter, to select to need anti-phase signal frequency range; Filter can be firstorder filter, second order filter Ge multi-stage filter.
Described in above-described embodiment, active noise elimination circuit can be realized by discrete electronic component, analog signal integrated circuit, digital signal integrated circuit or mixed signal (simulation+numeral) integrated circuit; And the noise that can be applicable to feed forward type (microphone is arranged in headset ear shell outside), reaction type (microphone is positioned at headset ear shell) or hybrid (feed forward type+reaction type) is eliminated earphone (wear-type, In-Ear).
Figure 10,12,14 is respectively filter circuit frequency response chart in prior art, embodiment 1-3, embodiment 4-6; Figure 11,13,15 is respectively active noise eradicating efficacy figure in prior art, embodiment 1-3, embodiment 4-6.From Figure 13, Figure 15, when each microphone noise signal path in embodiment 1-6 (being microphone filtering and amplifying circuit) adopts the combinational circuit of 2 or 3 variable gain amplifier of microphone+filters, maximum eradicating efficacy to ambient noise (frequency 100~500HZ) can reach 30 decibels, well more a lot of than the noise reduction of the typical noise suicide circuit of the prior art shown in Figure 11 (maximum is about 20 decibels).

Claims (9)

1. the active noise for earphone is eliminated circuit, it is characterized in that: after the ambient noise signal of each sound channel is collected by the microphone of earphone, through at least 2 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter.
2. the active noise for earphone according to claim 1 is eliminated circuit, it is characterized in that: after the ambient noise signal of each sound channel is collected by the microphone of earphone, through 2 microphone filtering and amplifying circuits, process respectively, noise signal after process on each road enters frequency mixer and mixes together with audio signal, through amplifier, amplify again, import loud speaker into; Each microphone filtering and amplifying circuit includes variable gain amplifier of microphone and filter.
3. the active noise for earphone according to claim 1 and 2 is eliminated circuit, it is characterized in that: between microphone and microphone filtering and amplifying circuit, preamplifier is set.
4. the active noise for earphone according to claim 1 and 2 is eliminated circuit, it is characterized in that: between microphone and microphone filtering and amplifying circuit, buffer is set.
5. the active noise for earphone according to claim 1 is eliminated circuit, it is characterized in that: filter is arranged between variable gain amplifier of microphone and frequency mixer.
6. for the active noise of earphone, eliminate circuit according to claim 1 or 5, it is characterized in that: filter is arranged between microphone and variable gain amplifier of microphone.
7. the active noise for earphone according to claim 6 is eliminated circuit, it is characterized in that: filter for band is logical, high pass or low pass filter.
8. the active noise for earphone according to claim 7 is eliminated circuit, it is characterized in that: filter is firstorder filter, second order filter Ge multi-stage filter.
9. the active noise for earphone according to claim 8 is eliminated circuit, it is characterized in that: described earphone is headphone or In-Ear Headphones.
CN201420216523.5U 2014-04-30 2014-04-30 Active noise abatement circuit for mobile phone Expired - Fee Related CN203840514U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201420216523.5U CN203840514U (en) 2014-04-30 2014-04-30 Active noise abatement circuit for mobile phone

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Application Number Priority Date Filing Date Title
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI549525B (en) * 2015-02-11 2016-09-11 With three-dimensional effect and to enhance the noise reduction of the environment noise loudspeakers active noise reduction headphones
CN106612472A (en) * 2015-10-23 2017-05-03 钰太芯微电子科技(上海)有限公司 Microphone-based regulation circuit and microphone
CN107212877A (en) * 2017-05-24 2017-09-29 西安电子科技大学 Variable gain mixer amplifier, biological signal collecting and process chip and system
CN111134956A (en) * 2019-12-24 2020-05-12 杭州鐵三角科技有限公司 Noise reduction earplug
CN112468918A (en) * 2020-11-13 2021-03-09 北京安声浩朗科技有限公司 Active noise reduction method and device, electronic equipment and active noise reduction earphone
CN114040289A (en) * 2021-11-08 2022-02-11 广州由我科技股份有限公司 Earphone noise reduction method and earphone

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI549525B (en) * 2015-02-11 2016-09-11 With three-dimensional effect and to enhance the noise reduction of the environment noise loudspeakers active noise reduction headphones
CN106612472A (en) * 2015-10-23 2017-05-03 钰太芯微电子科技(上海)有限公司 Microphone-based regulation circuit and microphone
CN107212877A (en) * 2017-05-24 2017-09-29 西安电子科技大学 Variable gain mixer amplifier, biological signal collecting and process chip and system
CN111134956A (en) * 2019-12-24 2020-05-12 杭州鐵三角科技有限公司 Noise reduction earplug
CN111134956B (en) * 2019-12-24 2021-02-19 海宁鐵三角科技有限公司 Noise reduction earplug
CN112468918A (en) * 2020-11-13 2021-03-09 北京安声浩朗科技有限公司 Active noise reduction method and device, electronic equipment and active noise reduction earphone
CN114040289A (en) * 2021-11-08 2022-02-11 广州由我科技股份有限公司 Earphone noise reduction method and earphone

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CF01 Termination of patent right due to non-payment of annual fee
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Granted publication date: 20140917

Termination date: 20190430