CN201422161Y - capacitor microphone - Google Patents

Abstract

The utility model discloses a capacitor microphone, which changes the conventional pickup mode, namely utilizes multiple cartridges to replace the existing single cartridge to complete pickup. The capacitor microphone comprises a plurality of capacitor poles for pickup, a plurality of pole casings and a special circuit portion (including impedance converters, a summer, a filter circuit and an output circuit), each capacitor pole is connected to an input end of the summer via a respective impedance converter, and the flexibility of the microphone is basically equal to sum of flexibility of thecapacitor poles, thereby increasing integral flexibility of the microphone, and further being capable of greatly increasing signal-to-noise ratio of the capacitor microphone. In addition, because eachcapacitor pole is provided with the independent pole casing, comb filtering effect can not be generated and frequency response and distortion factor can not be affected.

Description

A kind of condenser microphone

Technical field

The utility model relates to the microphone field, particularly a kind of condenser microphone.

Background technology

At present, the application of sound reinforcement system more and more widely, referring to Fig. 1, be a kind of basic meeting sound reinforcement system structural representation, the voice signal that microphone sends sound source is converted to the signal of telecommunication, after the sound console tuning, through power amplifier signal power is amplified again, send into the loud speaker public address.Wherein microphone (also claiming microphone) is as the source of sound reinforcement system, and can its every specific targets reach optimum and seem particularly important.

Sound is clear, and noise-free conference system and meeting-place environment are the ideal situations that meeting and audio engineering personnel pursue always, and this just requires further to improve the signal to noise ratio of condenser microphone.The approach that improves the condenser microphone signal to noise ratio roughly has two kinds, the one, the noise of reduction condenser microphone, the 2nd, the sensitivity that improves condenser microphone, because improve the effect of signal to noise ratio by the reduction noise very limited, thereby all be the signal to noise ratio that improves condenser microphone by the sensitivity that improves condenser microphone usually.Wherein the sensitivity of microphone is meant the ability of microphone acoustic-electric conversion, is specially under the acoustic pressure effect of unit, and microphone can produce great voltage.

In the prior art, at electret capacitor microphone, generally the sensitivity that a plurality of electric capacity cartridges improve condenser microphone is put in parallel connection in a sound head storehouse, referring to Fig. 2, it is the condenser microphone structural representation of two electric capacity cartridges parallel connection, in a sound head storehouse shell 5, be parallel with two electric capacity cartridges, specifically be the positive pole of the positive pole of electric capacity cartridge 1 and electric capacity cartridge 2 link together (position shown among Fig. 2 3), the negative pole of the negative pole of electric capacity cartridge 1 and electric capacity cartridge 2 link together (position shown among Fig. 2 4), the positive pole that electric capacity cartridge 1 and electric capacity cartridge 2 are common, reach electric capacity cartridge 1 and electric capacity cartridge 2 common negative poles and be connected respectively to emitter follower, emitter follower links to each other with the filtering output circuit again, a plurality of electric capacity cartridges are connected in parallel on a principle in the sound head storehouse and two electric capacity cartridges, and to be connected in parallel on the principle in the sound head storehouse identical, being connected in parallel between a plurality of electric capacity cartridges, make load each other between a plurality of electric capacity cartridges, though thereby the sensitivity of a plurality of electric capacity cartridge after being connected in parallel increases, the ability that its sensitivity improves is quite limited.And this mode only is applicable to the electret capacitor cartridge, and be not suitable for pure diaphragm electric capacity cartridge, because the field effect transistor of electret capacitor cartridge is directly to be welded on capacitance pole face in front, and the field effect transistor of pure diaphragm electric capacity cartridge is outside the electric capacity cartridge, and need polarizing voltage, so can not directly simple in parallel the use.

In view of this, can effectively not improve the technical scheme of condenser microphone sensitivity at present.

The utility model content

The utility model provides a kind of condenser microphone, to solve the problem of further raising condenser microphone sensitivity.

A kind of condenser microphone comprises a plurality of electric capacity cartridge of pickup, impedance transducer, adder, filter circuit and outlet lines of each described electric capacity cartridge correspondence of being used for:

The positive pole of each described electric capacity cartridge and negative pole are connected respectively to the input of adder through impedance transducer separately, and the output of described adder links to each other with described outlet line through filter circuit.

Each described electric capacity cartridge is separately positioned in separately the sound head storehouse shell.

Connecting line between each described electric capacity cartridge and adder has microphone tube connector separately respectively.

The shared microphone tube connector of all or part of connecting line between at least two described electric capacity cartridges and adder.

Described condenser microphone also comprises amplifier or emitter follower, is connected between the output and described filter circuit of described adder.

Described electric capacity cartridge is electret capacitor cartridge, backplane electric capacity cartridge or pure diaphragm electric capacity cartridge.

A kind of condenser microphone that the utility model provides, beneficial effect is: by changing pickup mode, promptly change multitone head pickup into by original single-tone head pickup, independently a plurality of electric capacity cartridges link to each other with adder respectively mutually, adder makes the overall sensitivity of condenser microphone be equivalent to a plurality of independent capacitance cartridge sensitivity sums, improve the sensitivity of condenser microphone greatly, and then can improve the signal to noise ratio of condenser microphone greatly.

Description of drawings

In order to be illustrated more clearly in the utility model embodiment or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is embodiment more of the present utility model, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is a kind of basic meeting sound reinforcement system structural representation in the prior art;

Fig. 2 is two sound head condenser microphone structural representations that constitute in parallel in the prior art;

The structural representation of a kind of condenser microphone that Fig. 3 provides for the utility model embodiment;

The pictorial diagram of a kind of condenser microphone that Fig. 4 provides for the utility model embodiment;

The another kind of condenser microphone pictorial diagram that Fig. 5 provides for the utility model embodiment;

The structural representation of the another kind of condenser microphone that Fig. 6 provides for the utility model embodiment;

Fig. 7 is the sensitivity and the frequency response curve of single-tone head condenser microphone in the prior art;

Condenser microphone sensitivity and frequency response curve that Fig. 8 provides for the utility model embodiment.

Embodiment

Below in conjunction with the accompanying drawing among the utility model embodiment, the technical scheme among the utility model embodiment is clearly and completely described, obviously, described embodiment only is the utility model part embodiment, rather than whole embodiment.Based on the embodiment in the utility model, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the utility model protection.

For making the purpose of this utility model, technical scheme and advantage clearer, the utility model execution mode is described in further detail below in conjunction with accompanying drawing.

At present, the application of sound reinforcement system more and more widely, wherein microphone is used to realize acoustic-electric conversion mainly comprise three parts: sound system (pick-up head), mechanical system (shell) and electricity system (circuit).

Microphone commonly used at present mainly contains polytypes such as moving coil microphone, condenser microphone, aluminium strip microphone by transduction principle, and wherein condenser microphone is widely used in important events such as meeting, recording, broadcast, news conference with its good performance, mainly comprises electret capacitor microphone, backplane condenser microphone and pure diaphragm condenser microphone etc.

The sound system of condenser microphone is mainly used in the function of finishing the acoustic-electric conversion, the electric capacity cartridge (comprise electret capacitor cartridge, backplane electric capacity cartridge and pure diaphragm capacitance pole first-class) of its main element for constituting by plate condenser, wherein comprise can be with the electrode of acoustic vibration and fixing electrode for plate condenser, on physics, plate condenser is being ignored under the situation of rim effect, and the computing formula of its capacitance is:

$C=\frac{\mathrm{\ϵ}\×S}{d}$ Formula 1

In the formula 1: C: the capacitance of plate condenser;

ε: the dielectric dielectric constant of its two interpolar of capacity plate antenna;

S: plate condenser two is interelectrode over against area;

D: plate condenser two interelectrode spacings.

When any one changes in ε, S, three parameters of d, the capacitance C of plate condenser just will change thereupon, because sound wave is a kind of vibration that is certain energy, when sound wave is beaten on plate condenser, spacing between the two-plate of plate condenser will change, suppose that the spacing change amount between two-plate is Δ d, capacitance change into Δ C, then

$\mathrm{\ΔC}=\frac{\mathrm{\ϵ}\×S}{d}-\frac{\mathrm{\ϵ}\×S}{d+\mathrm{\Δd}}=\frac{\mathrm{Co}\×\mathrm{\Δd}}{d+\mathrm{\Δd}}$ Formula 2

Wherein, Co is the initial capacitance of spacing when being d, and this moment, the change of condenser microphone capacitance will change with the variation of sound wave, according to Coulomb's law C=Q/U, can derive U=Q/C, wherein C is the capacitance between two-plate, U is the magnitude of voltage between two-plate, and Q is an electric weight; Voltage U between two-plate is that change with capacitance C between two-plate changes as can be seen, has so just realized the conversion of sound wave to the signal of telecommunication.

The condenser microphone the key technical indexes comprises: directive property, sensitivity, frequency response, maximum sound pressure level, signal to noise ratio etc., some is that different demands is arranged according to the different of use occasion and range of application in these indexs, as: directive property, sensitivity, frequency response etc., but some index demand for different use occasions and range of application all is the same, as: signal to noise ratio require high more good more, maximum sound pressure level requires to be the bigger the better etc.

The signal to noise ratio of condenser microphone is the ratio of signal and noise, is unit with dB (decibel) generally, and formula is seen formula 3:

$\frac{S}{N}=20\lg \frac{E}{\mathrm{En}}$ Formula 3

In the formula 3, E is the sensitivity of condenser microphone, and unit is mv/pa; En is the noise voltage of condenser microphone, and unit is mv, and S is a semaphore, and N is a noisiness, and the unit of signal to noise ratio S/N is dB.

Through type 3 as seen, the approach that improves the condenser microphone signal to noise ratio roughly has two kinds of methods, the one, reduce the noise of condenser microphone, the 2nd, the sensitivity that improves condenser microphone.

The effect that improves signal to noise ratio by the reduction noise is very limited, because the cartridge of condenser microphone work itself is more stable, the thermal noise that self produces under muting environment is extremely low in theory, the noise of whole capacitor microphone is mainly derived from Circuits System, except selecting low device of noise and rational deployment circuit board for use, there are not other more efficient methods to reduce the background noise of circuit, therefore it is limited reducing noise, because all can there be background noise in each active device at work.

Therefore, referring to Fig. 3 to Fig. 6, the utility model embodiment provides a kind of condenser microphone, improves the signal to noise ratio of condenser microphone by the sensitivity that improves microphone.

The sensitivity of condenser microphone depends primarily on sensitivity E of electric capacity cartridge own and circuit multiplication factor Av, output voltage Eout=E * the Av of condenser microphone, the output noise En=Av of condenser microphone * circuit background noise, wherein Av is the multiplication factor of condenser microphone.

Improving circuit multiplication factor Av can make output voltage increase, but output noise En also can increase on year-on-year basis simultaneously, therefore improve circuit multiplication factor Av and inadvisable, but also can make circuit when high sound pressure, enter clipping state in advance, so general condenser microphone circuit all adopts 1: 1 the way of output, i.e. multiplication factor Av=1.

And raising electric capacity cartridge sensitivity meeting simply declines to a great extent electric capacity cartridge sound pressure level, under the situation of high sound pressure, produce slicing easily, can produce the extraction electrode situation in addition, produce explosion sound, serious meeting can't work on the electric capacity cartridge, causes the damage of condenser microphone.

In the prior art, at electret capacitor microphone, generally the sensitivity that a plurality of electric capacity cartridges improve condenser microphone is put in parallel connection in a sound head storehouse, the shared sound head storehouse cavity of a plurality of electric capacity cartridges, meeting load each other between then a plurality of electric capacity cartridges, the sensitivity of each electric capacity cartridge will no longer be before self sensitivity of single electric capacity cartridge, and can significantly reduce, thereby it is quite limited to adopt this mode to improve the ability of condenser microphone sensitivity; In addition, on operatic tunes structure, also can influence each other between a plurality of electric capacity cartridges, it is the ante-chamber that the back cavity of previous electric capacity cartridge can become a back electric capacity cartridge, therefore can produce a very large impact indexs such as frequency response, directive property, the distortion factors, thereby produce more serious comb-filter effect, frequency response and the harmonic distortion meeting very cakes with moulded designs that becomes can not well reduce original source of sound, even can't reduce original source of sound.

And a kind of condenser microphone that the utility model embodiment provides referring to Fig. 3, comprises two electric capacity cartridges: electric capacity cartridge 311 and electric capacity cartridge 312; Adder 34; Filter circuit 36: and outlet line 37;

Two electric capacity cartridges (electric capacity cartridge 311 and electric capacity cartridge 312) are connected to the input of adder 34 respectively through impedance transducer (impedance transducer 331 and impedance transducer 332) separately, concrete, the positive pole 301 of electric capacity cartridge 311 and negative pole 302 are connected to the input of adder 34 through impedance transducer 331 separately, the positive pole of electric capacity cartridge 312 and negative pole are connected to the input of adder 34 through impedance transducer 332, that is to say, each electric capacity cartridge is furnished with an impedance transducer, impedance transducer is converted to Low ESR with the high impedance of previous stage circuit, so as better and the next stage circuit be complementary;

The output of this adder 34 links to each other with outlet line 37 through filter circuit 36.

Further, each electric capacity cartridge is separately positioned in the sound head storehouse shell, and promptly electric capacity cartridge 311 and electric capacity cartridge 312 are separately positioned in two sound head storehouse shells (sound head storehouse shell 321 and sound head storehouse shell 322).

As seen, the condenser microphone that the utility model embodiment provides, by changing pickup mode, promptly change multitone head pickup into by original single-tone head pickup, independently a plurality of electric capacity cartridges link to each other with adder respectively mutually, adder makes the overall sensitivity of condenser microphone be equivalent to a plurality of independent capacitance cartridge sensitivity sums, the sensitivity that improves condenser microphone greatly, and then can improve the signal to noise ratio of condenser microphone greatly.

Condenser microphone shown in the present embodiment comprise two independently the sound head (referring to sound head 411 among Fig. 4 and sound head 412, or sound head 511 among Fig. 5 and sound head 512), wherein each sound head is made of sound head storehouse shell and the electric capacity cartridge that is arranged in the shell of sound head storehouse, in the practical application, be not limited to two independently sound heads, can comprise that three or more independently sound heads form,, and then further improve the signal to noise ratio of condenser microphone with the sensitivity of further raising condenser microphone.

In conjunction with referring to Fig. 4, connecting line between each electric capacity cartridge and adder can have microphone tube connector separately respectively, be that connecting line between electric capacity cartridge 311 and electric capacity cartridge 312 and the adder 34 can have microphone tube connector 421 and microphone tube connector 422 separately respectively, wherein the microphone tube connector can adopt the microphone flexible pipe, also can adopt the microphone hard tube, like this, can so that a plurality of sound head respectively towards different directions, be that a plurality of sound heads can carry out pickup from a plurality of directions, if what adopt is the microphone flexible pipe, all right manual adjustment pickup direction is to satisfy multiple demand.

In actual applications, all or part of connecting line between at least two described electric capacity cartridges and adder also can a shared microphone tube connector, in conjunction with referring to Fig. 5, connecting line between electric capacity cartridge 311 and electric capacity cartridge 312 and the adder 34 can a shared microphone tube connector 52, at this moment, a plurality of sound heads can carry out pickup at some positions, and are more targeted.

The type of electric capacity cartridge can be electret capacitor cartridge, backplane electric capacity cartridge or pure diaphragm electric capacity cartridge, a plurality of electric capacity cartridges among the utility model embodiment can all adopt same type electric capacity cartridge, also can adopt the electric capacity cartridge collocation of different types to use respectively, satisfy multiple actual needs.

Can be according to the type difference of the electric capacity cartridge that adopts, the position that impedance transducer is placed is also different, such as what adopt is the electret capacitor cartridge, then impedance transducer is in electret capacitor cartridge the inside, when selecting back-polar type electric capacity cartridge or pure diaphragm electric capacity cartridge for use, impedance transducer is in electric capacity cartridge outside, in the inside, sound head storehouse.

Further, referring to Fig. 6, the condenser microphone that the utility model embodiment provides, can also comprise emitter follower 35, emitter follower 35 is connected between the output and filter circuit 36 of adder 34, because emitter follower 35 output impedance are less, therefore, can further improve the carrying load ability of condenser microphone, prolong the distance of signal transmission, and antijamming capability, in the practical application, can adopt amplifier to substitute emitter follower, generally adopting multiplication factor Av is 1 amplifier.

In the practical application, in order further to increase antinoise, the antijamming capability of condenser microphone, can also comprise electronic balancer or transformation balancer,, then electronic balancer is connected in series between the input of the input of adder 34 and emitter follower 35 if adopt electronic balancer; If adopt the transformation balancer, then the transformation balancer be connected to the filter circuit back.Electronic balancer and transformation balancer belong to this area electronic device commonly used, and the concrete occupation mode to it does not limit herein, and existing occupation mode all can be used.

The condenser microphone that the utility model embodiment provides, by changing pickup mode, promptly change multitone head pickup into by original single-tone head pickup, independently a plurality of electric capacity cartridges link to each other with adder respectively mutually, adder makes the overall sensitivity of condenser microphone be equivalent to a plurality of independent capacitance cartridge sensitivity sums, improve the sensitivity of condenser microphone greatly, and then can improve the signal to noise ratio of condenser microphone greatly.

In addition,, promptly have independently acoustic construction,, can be good at reducing original source of sound so can not interact its frequency response and total harmonic distortion can not produce comb-filter effect because each electric capacity cartridge all has independently sound head storehouse shell.

Once more, because the prime of a plurality of electric capacity cartridges is independently, therefore the reliability and the applicability of condenser microphone have been improved greatly, promptly in a single day working as one of them electric capacity cartridge breaks down for a certain reason and can't work, can not influence the work of other electric capacity cartridge so, thereby make condenser microphone to work on.

The sensitivity of single pure diaphragm electric capacity cartridge at present can be accomplished-44.7dB (being 5.82mv/pa) preferably, that can not do is too high, because when the too high words of sensitivity will reduce spacing between pole plate, or increasing polarizing voltage, like this, in big acoustic pressure, can produce the phenomenon of extraction electrode under the moist or dusty situation, referring to Fig. 7, sensitivity and frequency response curve for single-tone head condenser microphone in the prior art, this curve chart is to adopt the less relatively impedance transducer of noise, it is the 2SK118R technotron of Toshiba, its index is roughly Idss=0.4mA, En=0.5dB (F=1KHz, Rg=1M Ω), as seen Cis=8.2P selects for use the 2SK118R technotron to have lower noise than general junction type pipe.Circuit output noise test result is 1.5 μ V under the situation of no signal input, if the signal to noise ratio that the words of single-tone head pickup obtain is: S/N (dB)=20lgE/En=20lg5.82mv/1.25 μ V=20lg4656=73.4dB, that is to say that the signal to noise ratio of 73.4dB is that present single-tone head condenser microphone is than higher index basically.Current, technology and circuit design by very complicated can obtain the signal to noise ratio about 85dB.

And the condenser microphone that adopts the utility model embodiment to provide, need not complicated technology and circuit design, only need by changing pickup mode, promptly change multitone head pickup into by original single-tone head pickup, independently a plurality of electric capacity cartridges link to each other with adder respectively mutually, its sensitivity can be increased to-30.5dB (being 29.85mv/pa), under high sensitivity, can not influence sound pressure level and frequency response.Referring to Fig. 8, the sensitivity and the frequency response curve of the condenser microphone that provides for the utility model embodiment, signal to noise ratio is: S/N (dB)=20lgE/En=20lg29.85mv/1.25 μ v=20lg23883=87.56dB.

Comparison by Fig. 7 and Fig. 8 can find out obviously that the sensitivity of the condenser microphone that employing the utility model embodiment provides and the curve of frequency response are more level and smooth, and the whole gradient is littler.

Need to prove, in this article, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thereby make and comprise that the article of a series of key elements or equipment not only comprise those key elements, but also comprise other key elements of clearly not listing, or also be included as this article or equipment intrinsic key element.Do not having under the situation of more restrictions, the key element that limits by statement " comprising ... ", and be not precluded within the article that comprise described key element or the equipment and also have other identical element.

The above is preferred embodiment of the present utility model only, is not to be used to limit protection range of the present utility model.All any modifications of within spirit of the present utility model and principle, being done, be equal to replacement, improvement etc., all be included in the protection range of the present utility model.

Claims (6)

1, a kind of condenser microphone is characterized in that, comprises a plurality of electric capacity cartridge of pickup, impedance transducer, adder, filter circuit and outlet lines of each described electric capacity cartridge correspondence of being used for:

The positive pole of each described electric capacity cartridge and negative pole are connected respectively to the input of adder through impedance transducer separately, and the output of described adder links to each other with described outlet line through filter circuit.

2, condenser microphone according to claim 1 is characterized in that, each described electric capacity cartridge is separately positioned in separately the sound head storehouse shell.

3, condenser microphone according to claim 1 is characterized in that, the connecting line between each described electric capacity cartridge and adder has microphone tube connector separately respectively.

4, condenser microphone according to claim 1 is characterized in that, the shared microphone tube connector of all or part of connecting line between at least two described electric capacity cartridges and adder.

5, condenser microphone according to claim 1 is characterized in that, described condenser microphone also comprises amplifier or emitter follower, is connected between the output and described filter circuit of described adder.

6, condenser microphone according to claim 1 is characterized in that, described electric capacity cartridge is electret capacitor cartridge, backplane electric capacity cartridge or pure diaphragm electric capacity cartridge.

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