CN1678135B

CN1678135B - Remote control of phantom power supplied microphones

Info

Publication number: CN1678135B
Application number: CN2005100588508A
Authority: CN
Inventors: I·O·塞科尼克
Original assignee: AKG Acoustics GmbH
Current assignee: AKG Acoustics GmbH
Priority date: 2004-03-30
Filing date: 2005-03-30
Publication date: 2012-06-20
Anticipated expiration: 2025-03-30
Also published as: EP1585359B1; EP1585359A1; JP4833572B2; CN1678135A; TWI358954B; JP2005287050A; TW200605699A

Abstract

The invention relates to a method for the remote control of a microphone, which comprises at least one microphone capsule (9), and at least one additional power receiver, selected from the group of audio amplifiers (10), power supply circuits (11), processors, control electronics (39), A/D and D/A converters (44, 46), LED displays (25), etc., and whose energy supply occurs by a phantom power unit (31) through the cable conductors (1, 2) of the audio cable, the so-called phantom power supply. The invention is characterized in that a frequency-modulated voltage is applied as a control signal to at least one of the two cable conductors (1, 2) through which the phantom power supply also occurs, and in that the frequency-modulated voltage, on the microphone side, is applied to a control electronics (39), for example a microcontroller or a CPLD, which sends commands to individual power receivers according to the frequency-modulated control signals.

Description

The long-range control method of phantom power supplied microphones

Technical field

The present invention relates to a kind of method of Long-distance Control microphone, this microphone comprises from audio frequency amplifier, power-supplying circuit; Processor, control electronic device, A/D and D/A converter; A microphone capsule at least of selecting in the group of light-emitting diode display etc.; With at least one other power receiver, their power supply is a phantom power unit from the cable conductor that passes through audio frequency cable, i.e. so-called " phantom power supplied ".

Background technology

The power supply power supply of microphone is to be provided by individual power supply traditionally, for example, utilizes frequency mixer.In phantom power supplied process, the positive pole of feed voltage is that two the equal feed resistance (feeder residence) through two cable conductors of audio frequency cable apply.The electric current that returns flows through from the 3rd lead of the electric connection 1 that is connected to the XLR plug.For can effectively utilize for Electret Condencer Microphone by the phantom power supplied voltage that provides, the current drain of microphone should be as much as possible little, to prevent the excessive pressure drop on feed resistance.The maximum current consumption of 48-V Electret Condencer Microphone is 10mA.According to DIN EN61938 (IEC268 originally), phantom power here is standardized.

For in the polarizing voltage in 20-100V direct voltage scope normally of generation value on the microphone membrane, can mainly utilize combinational circuit parts or electric pressure converter.Remaining microphone electronics generally is by linear regulation power supply to be provided, and this can maintain a predetermined value with power feed voltage or source current.For the microphone with little power consumption, the power supply of the type is suitable.By using processor, when A/D converter, light-emitting diode display or the like caused the power consumption in the microphone to increase, this linear regulation can become problem when for example.In this case, the major part by the obtainable energy of phantom power is depleted in linear trim.Yet, according to standard because phantom power is by feed resistance restriction electric current, so the maximum supply power voltage that is used for audio amplifier because reduce immediately in the linear regulation of microphone, this causes the reduction of the maximal audio output voltage of microphone.

Other problem comprises the generation of polarizing voltage.Normally microphone membrane is applied this voltage through a high-ohmic resistance.Here, required power is very low.Being used to produce this efficient adjuster that is actually the inactivity polarizing voltage also is difficult to construct.

Another problem is the Long-distance Control about microphone.Utilize microphone, exist a kind of needs of growth, can regulate or change important microphone parameters through Long-distance Control.These parameters are included in type, sequence number, the weakening degree and can be connected filter with that is used for sound signal from the calibration data of manufacturer and signal of directive property, the phantom power (12V, 24V or 48V) of associated sensitivity, the microphone of polarizing voltage and Electret Condencer Microphone on the film.

DE 3 933 870 A1 files disclose a kind of method of Long-distance Control microphone parameters, these parameters such as directive property, step sound filter or initial damping.In the method, the supply power voltage that is sent to cable conductor is to regulate through a remote control unit, and for example, in a mixture table, mode is the control information that the value of voltage is represented microphone.At microphone here, supply power voltage is not coupled, and is applied to an evaluation circuits, and evaluation circuits produces the function of a control signal as the amount of supply power voltage.Through this method of transfer of data, have only a spot of control information can be transferred to microphone, therefore, also having only some parameters is can be by Long-distance Control in microphone.

US 6 028 946 A (with corresponding EP 0 794 686 A2) file discloses a digital microphone.Audio signal is digitized through analogue-to-digital converters, and two passage digital audio signals of generation are transmitted through the two line conductors of a symmetry or the amplifier of an association.The power supply of microphone is to provide through these two symmetrical line conductors.Mention indirectly in passing, in the amplifier of association, pulse can be modulated onto on the supply voltage of microphone, the Long-distance Control that this sets as loud speaker.It must be noted that in context the follow-up transmission of the notion of digital microphone and digital signal is different from a simulation microphone fully, wherein analog signal transmits through the phantom power line.The transmission that transmits the other modulation signal on the circuit of digital signal does not at the same time cause any problem because digital audio and video signals can be easily from an other modulation signal separately.

An other problem that does not solve best so far is the generation about polarizing voltage on the film of Electret Condencer Microphone.The level of polarizing voltage is directly to be included in the level of sensitivity of microphone capsule.As a result, under the help of polarizing voltage, also possibly come the sensitivity of control capacittance formula carbon capsule.Under the situation that the single film with polarizing voltage is supplied power separately, be used in combination two film carbon capsules, this is particularly advantageous, because these carbon capsules not only allow to regulate sensitivity, and allows to regulate directive property.

It is known how under the help of fixed resistance or semifixed resistor, regulating polarizing voltage.In this process, in the assembling of microphone, the disposable adjusting of polarizing voltage takes place.Here, directive property fixing resistance ratios once capable of using is by predetermined.Utilize this method, cause, and the tolerance limit compensation of the sensitivity that is caused by ageing process has difficulty by the assembling of microphone capsule.For this purpose, in the audio frequency measuring process of the sensitivity in the assembled state of microphone, with a compensation that needs polarizing voltage.The tolerance limit compensation of under different directive property situation, carrying out sensitivity is also unlikely.

The U.S. 4,541,112 A (with EP 0 096 778 B1 of correspondence) number file discloses an electroacoustic transducing device system with scalable pulse generator, and DC converts AC to electric current.Be connected to a power receiver that transformer permission inductance is decoupled single of pulse generator.Current supply circuit is to be inductively coupled to the alternating current that is produced by pulse generator through the separate winding on the transformer.This document is included in the description of this paper, as a reference.

Summary of the invention

About the power supply of microphone, need a kind of solution, the power supply that is wherein obtained by phantom power is used by optimum; And be converted into like audio amplifier microphone capsule, processor; Controller, A/D converter, the required operating voltage of output receiver that light-emitting diode display or the like is independent.Here, target will be to utilize the part of the power supply that obtains through phantom power to supply power to audio amplifier as wide as possible.

Utilize a microphone that comprises the power-supplying circuit that is used for independent power supply receiver can reach these targets; The characteristic of its microphone shows as; Power-supplying circuit comprises that a direct current that will transmit through the cable conductor of voice-frequency cable converts the control unit of alternating current into; A transformer that is connected to control unit; With the current supply circuit that is used for independent power supply receiver, wherein current supply circuit is inductively coupled to the alternating current that is produced by control unit through the separate winding on the transformer, and coupled to each other between these current supply circuits.

In this process, desired all voltages of above-mentioned power supply receiver are to be produced by a power-supplying circuit, are for example produced by a DC/DC transducer, and it has following characteristics.This power-supplying circuit is to be conditioned by this way or to operate, and a power adaptation to the phantom power unit is promptly arranged.Therefore, the power supply of the attainable maximum possible in phantom power unit can be always consumed by the power-supplying circuit of microphone.The source current drain of power-supplying circuit is constant.Therefore, with respect to the phantom power unit, power-supplying circuit similarly is a constant current sink.The independent current supply circuit of single power supply receiver passes through transformer by uncoupling in power-supplying circuit; To go to satisfy the demands of different of single power receiver with as far as possible little power loss: the high voltage and the little electric current that are used for polarizing voltage; Medium voltate be used for the medium current consumption of audio amplifier, and low-voltage that is used for digital electron device and big electric current.

According to the present invention, the advantageous effects of Electret Condencer Microphone is tangible: utilize the power supply power supply notion that proposes, the electric energy of being realized by the phantom power unit optimally is employed.As a result, microphone can be provided new function (for example, Long-distance Control, new operating concept, the automatic possibility of compensation, or the like), and the maximal audio output voltage of microphone remains unchanged.Basically the generation that is the polarizing voltage of no power consumption is actually as being taken place by the byproduct of the simple other coil generation on transformer.

An other advantage is; Use result as a high as far as possible ohm level; Input place at power-supplying circuit utilizes a constant power supply, and the switching fluctuation of power-supplying circuit or the switching fluctuation of DC/DC transducer can be filtered easily.

Be utilized in the adaptation possibility that increases in the microphone; As change the change of microprocessor control signal of lasting variation and storage calibration data of the directive property of polarizing voltage and sensitivity thereof, two film carbon capsules, and the modification of frequency range, the modification of maximal audio output voltage; Or the modification of the THD of audio amplifier; Therefore exist a kind of needs, promptly through a Long-distance Control, it is said that basically with higher rate will be passed to microphone.

According to the present invention; These targets can reach through the method for Long-distance Control microphone; It is characterized in that a fm voltage is to be applied at least one in two cable conductors as control signal, through cable conductor; Also Phantom Power can take place; And be applied to a control electronic device at the fm voltage of microphone side, and for example a microcontroller or a CPLD (complex programmable logic equipment), microcontroller or a CPLD can send order according to fm control signal and give single power receiver.

In the method, a fm voltage is superimposed upon on the supply power voltage of phantom power.Transfer of data be from a transmitter through audio line to microphone, for example, transmitter is to be configured in a mixture table or the equipment before the mixture table.The carrier frequency of FSK modulation here is the audio range that is higher than by the microphone transmission.

Through utilizing frequency-modulated signal transmission, compare with utilizing galvanic transmission, can obtain a higher basically message transmission rate.As a result, utilize a certain protocol, a large amount of parameters can be transmitted.The preferably about 100kHz of the carrier frequency that is used to modulate, they can utilize filter from sound signal, to separate.

This requirement for the low tolerance in the polarizing voltage that satisfies Electret Condencer Microphone; For example, consider sensitivity, arrive ± tolerance limit of 0.5dB; This needs a kind of solution, even allow under the assembled state of microphone, also can carry out the flexible of polarizing voltage.

According to the present invention, this can obtain through Electret Condencer Microphone, it is characterized in that; Electret Condencer Microphone comprises at least one circuit that is used to regulate polarizing voltage, and the circuit of wherein regulating polarizing voltage comprises the analog regulation loop that provides a non-regulation voltage, and a digital regulation loop; Wherein, digital regulation loop comprises control electronic device, for example a microprocessor or a CPLD; Offer a desired value that is used for polarizing voltage of analog regulation loop; It utilizes correction factor to calculate, and the purpose in order to feed back, and the output of analog regulation loop is to be connected with the control electronic device.

In this process, polarizing voltage is to regulate through a voltage regulation loop that is integrated in the microphone.The desired value of polarizing voltage is to be based upon in advance in this circuit through D/A converter by the control electronic device.As a result, can carry out the classification fine setting of polarizing voltage.The desired value of polarizing voltage also can be transferred to the control electronic device through Long-distance Control.The tolerance limit of the polarizing voltage that obtains depends on the tolerance limit and the thermal response of reference voltage source now.

The adjusting of the polarizing voltage through digital control regulating loop in microphone allows the adjusting of remote-controllable of the polarizing voltage of point-device, jamproof and Electret Condencer Microphone.As a result, in the process of the manufacturing of Electret Condencer Microphone and measuring technique checking, possibly obtain that narrow tolerance limit requirement does about the ten minutes of sensitivity and directive property.The advantage that the remote-controllable adjustment of polarizing voltage has is, no longer is necessary through regulating again of fixed resistance or semifixed resistor; This fact has a good effect aspect cost.Compare with the existing solution of utilizing changeless polarizing voltage, the relevant following other possibility of Electret Condencer Microphone according to the present invention can occur.

As the function of the independent characteristic of two film carbon capsules, under the situation of regulating directive property, different microphone sensitivity can be compensated differently, and can store the needed correction factor that requires of compensation polarizing voltage.

For example, with aforesaid Long-distance Control, polarizing voltage can be calibrated in the measurement of audio frequency process of the microphone of closing, and correction factor can be stored once more.

In operating process, can change the polarizing voltage of Long-distance Control microphone and what point to effect is that special advantage is arranged.For example, microphone can followed on the audio frequency like the mobile performer in the performance at arenas.

Allow the aging recalibration that causes of microphone sensitivity according to Electret Condencer Microphone of the present invention, and there is no need to dismantle microphone, this means the saving of consumer's expense again.In the process of changing microphone capsule, therefore the original sensitivity of microphone also can regulate afterwards again, that is to say, after merging, adjusts through Long-distance Control.

Description of drawings

Below, further explain the present invention with reference to accompanying drawing.In the drawings:

Fig. 1 representes the block diagram that has an Electret Condencer Microphone of power-supplying circuit according to of the present invention;

Fig. 2 representes the block diagram according to the embodiment of an Electret Condencer Microphone with power-supplying circuit of the present invention;

Fig. 3 represent according to a transistor-LED of the present art constant-circuit diagram of power supply;

Fig. 4 representes the circuit diagram with the transistorized stabilized power source of counter coupled according to the present art;

Fig. 5 representes to be connected to a block diagram of the Electret Condencer Microphone of remote control unit;

Fig. 6 representes to have the block diagram of an Electret Condencer Microphone of the integrated circuit that is used to regulate polarizing voltage; With

Fig. 7 representes to regulate the circuit of polarizing voltage, comprises a simulation and a digital regulation loop.

Embodiment

Fig. 1 is the block diagram of expression according to the critical piece of a microphone of the present invention.Phantom power at the microphone shown in Fig. 5 is to be carried out through the identical feed resistance 32,33 of value by phantom power unit 31, this feed resistance the 32, the 33rd, be configured in can be in mixture table or mixture table before the back of three pole sockets 4 of a for example XLR socket.Such phantom power is to be illustrated among Fig. 5.According to standard, three phantom power are possible: the correlation that is used for the feed resistance of 12V, 24V or 48V power supply is respectively 680 Ω, 1.2K Ω, or 6.8K Ω.The cable conductor that circuit 1 here and 2 representatives are provided by phantom power unit; Circuit 3 representatives are typically connected to the ground wire of the cable shield of ground connection.Through audio frequency cable, promptly through circuit 1,2 and resistance 5,6, phantom power unit 31 is connected to the input according to power-supplying circuit 11 of the present invention.Electric capacity 7 is with respect to the level and smooth supply power voltage in ground.Resistance 5 and 6 is the feed resistance in the microphone.Use them so that the power supply of microphone is decoupled from the output of audio amplifier 10.The feed resistance 5 and 6 of microphone is assigned with the other interior resistance as phantom power 31.When the interior resistance of phantom power unit equals the interior resistance of power-supplying circuit 11 in the microphone, there is electric energy adaptive (poweradaption).Like this, under the situation of power adjustments, the voltage of half the phantom power is the supply power voltage that is used for power-supplying circuit 11.This electric energy of the maximum that can be produced by phantom power unit 31 is the parts of distributing to all energy consumptions in the microphone through power-supplying circuit 11 with the form of DC/DC transducer now.Dump energy here is to be used by audio amplifier 10, to obtain the high as far as possible maximal audio output voltage of microphone.About different supply voltages (according to the 12V of standard, 24V or 48V), can come design circuit by this way, promptly automatically produce adaptive to the electric energy of different phantom power.This task is to be born by the control unit 12 that hereinafter is described then.

Power-supplying circuit 11 comprises 13, one control units 12 of a power supply and a transformer 14 that is connected to control unit 12.Control unit 12 with transformer 14 forms a circuit unit, and wherein dc voltage converts AC voltage to.In this case, transformer is the part of oscillation generating circuit.In general, alternating current also can be produced by the control unit that is independent of transformer 12.12 of control units comprise a cycle of oscillation that is independent of transformer, produce alternating current.Transformer only plays the function that alternating current is converted into independent output voltage.

In a preferred embodiment, the AC signal has the frequency that scope is 100-130kHz.But also free oscillation of AC signal; This expression is used for the most simply possibility of embodiment of such circuit.The frequency range that unique important factor is the AC signal must be outside audio range, and not produce any interference to sound signal, this interference can not be eliminated by simple filtering.On the other hand, frequency should be too not high yet, because otherwise, the efficient of circuit reduces, and possibly have the transmission interference.

Utilize another advantage of the frequency of 100-130kHz to be, this frequency also can be used as the recurrent pulse of the control electronic device 39 that provides in the microphone.As a result, the interference signal that digital technology produces is minimized, and is between the frequency of oscillation of time digit period and DC/DC transducer, to produce because there is not the product of additional mixing.

The AC signal that produces is applied to transformer 14.As the result of separate winding independent on transformer, formed the current circuit 15,16,17 that separates, to supply with independent energy consumption parts.This decouples feasible, with as far as possible little power loss, gives the consumable part that needs high voltage and low current simultaneously, and the consumable part power supply that needs high current drain and low-voltage.Diode 18,19,20 in independent current supply circuit 15,16,17 is represented a rectifier circuit that the AC voltage transitions is become dc voltage with capacitor 21,22,23.Certainly, can in independent current supply circuit, provide with more high efficiency rectifier from the more complicated of the present art.Current supply circuit 16 is used to offer microphone capsule 9 with polarizing voltage, and this is to be applied to microphone capsule 9 through resistance 8.

Certainly the invention is not restricted to Electret Condencer Microphone, because the microphone of any kind of, especially dynamic microphones can be connected to phantom power.Independent power receiver is to be supplied power with the same manner shown in Fig. 1 and 2 by phantom power unit.But under the situation of dynamic microphones, polarizing voltage is optional, does not therefore need current supply circuit 16.

Guaranteed the absorption of constant source electric current in the use of the constant0current generator 13 of the input of DC/DC transducer.Compare with phantom power unit 31, constant0current generator 13 similarly is a constant current sink, a constant0current generator of its expression power-supplying circuit 11.Constant0current generator 13 with high as far as possible ohm level in other effect, simplified the filtering of the switching fluctuation that produces in the DC/AC transfer process, thereby it has prevented the stack of the interference on sound signal simultaneously.The electronic building brick of the type is known for those skilled in the art of the state of the art of being familiar with this area.Examples of circuits from the constant0current generator of the present art is shown in Fig. 3 and 4.Fig. 3 representes to have " transistor LED " constant0current generator of bipolar transistor.About this current feedback circuit, LED is operated on the sense of current.As a result, a constant voltage imposes on LED, and such voltage also is applied on transistorized base emitter diode with emitter resistance connected in series.Therefore, the electric current that is brought by this current feedback circuit is I=(U _LED-U _Bc)/Re, wherein U _LEDBe pressure drop at LED, U _BcBe base-emitter voltage, Re is an emitter resistance.

Circuit among Fig. 4 comprises a constant0current generator, and it has the

degenerated transistors

28,29 of two counter coupled, and the integrated constant0current generator 30 of another one.This circuit is preferred, because consider that from constant current and higher initial resistance aspect this circuit has better characteristic, thereby is preferred.Current feedback circuit 30 is at initial resistance R _CVoltage drop of last generation, this pressure drop equals the voltage drop U on the emitter resistance Re of transistor 28 _RCHere the electric current of constant0current generator is I=U _Rc/ Re.Transistor 29 forms a counter coupled degeneration system with transistor 28, to guarantee the identical voltage drop at resistance R c and Re.As a result, the electric current I of current feedback circuit also keeps constant.Therefore the electric current of current feedback circuit 30 is the constant current 1/100 that finally flow into DC/DC transducer 11.

Certainly, the constant0current generator of other type can be provided also, for example, have a current feedback circuit of rp-op amp, Howland current feedback circuit or the like.

The supply power voltage that is used for audio amplifier 10 that is produced by power-supplying circuit 11 is not conditioned in a preferred embodiment.In the current supply circuit 16 of microphone capsule 9, a regulating

circuit

47,48 is provided between diode 18 and resistance 8, comprise a digital regulation loop 47 and an analog regulation loop 48, be provided for the polarizing voltage that is applied to microphone capsule 9.Fig. 6 representes the regulating

circuit

47,48 of a so preferred remote-controllable with Fig. 7.The required control signal of the adjusting of polarizing voltage can be transmitted through in two cable conductors 1 and 2 at least one.The detailed structure and the method for operation of such regulating

circuit

47,48 are described hereinafter.If electric current that provides and voltage limit are not in the already provided restriction of digital circuit part, in remaining current supply circuit, also regulating circuit can be provided.In the preferred embodiment of Fig. 1 and 2, in the current supply circuit 15 of audio amplifier 10, regulating circuit is not provided.As a result, whole electric power (be not to use at other circuit part, like processor, control electronic device 39, the polarizing voltage of microphone capsule 9, A/D or D/

A converter

44,46, light-emitting diode display 25) can be used for audio amplifier 10.As a result, high maximal audio output voltage can obtain in the current savings design of audio amplifier 10, to obtain a high maximal audio output voltage.In principle, the supply power voltage of consequent audio amplifier 10 also can surpass the voltage that phantom power realizes.Because the How It Works of power-supplying circuit 11 also possibly produce the very simply supply power voltage of positive and negative for audio amplifier 10.As a result, audio amplifier 10 also can utilize ground connection as rest potential.The feed voltage of audio amplifier (10) therefore can be about the ground connection symmetry.

In a further advantageous embodiment, the DC/DC transducer 11 of the above-mentioned type is with about 82% efficient work.Because, even at the best of times, power loss is also arranged at the DC/DC transducer, so if possible, consumers connected in series is favourable to the DC/DC transducer.As the result who utilizes constant0current generator 13; Possibly easily connect consumers with constant-current consumption; For example logic power 24; Be connected to with thinking serial DC/DC transducer 11 like control electronic device 39, or light-emitting diode display 25, A/D or D/

A converter

44,46 etc. are realized a fixedly direct current.

The corresponding embodiment of power-supplying circuit 11 is illustrated among Fig. 2.Compared to Figure 1, difference is that to have only polarizing voltage and the voltage that is used for audio amplifier 10 be to produce through the DC/DC transducer.Other consumers is used to control the logic power 24 of the fixing predetermined direct current of electronic device 39 or light-emitting diode display 25 as towering acquisition, is connected in series to the DC/DC transducer.The DC/DC transducer 11 connected in series of digital power serves as active load resistance; The electric weight that wherein in this resistance, uses does not convert heat energy to, but converts the employable power supply of polarizing voltage on audio amplifier 10 and the microphone capsule 9 to sizable ratio.

As shown in Figure 2, with the logic power 24 of realizing reference voltage or other digital electron device, a Zener diode 27 is provided, it is particularly well suited to stablize this voltage.Through this diode 27, do not consumed but any electric current of being transmitted by constant0current generator 13 is released to the earth.In principle, can use any other constant0current generator or shunt regulator, substitute Zener diode 27.

Delivered power is the electric current and the product that is applied to the voltage of power-supplying circuit 11 of constant0current generator 13.In the block diagram of Fig. 1, whole voltage imposes on DC/DC transducer 11, and all voltages are to produce through the DC/DC transducer.In the block diagram of Fig. 2, voltage is divided into a part that is applied to DC/DC transducer 11 and second part that is applied to LED25 and digital power.The DC/DC transducer is represented an effective initial resistance of LED25 or digital power.Because the current drain of digital power is not constant, but electric current I keeps constant through current feedback circuit 13, depends on the operating state of digital electron device and the excess current that exists must be emitted through Zener diode 27.For the power supply of audio amplifier 10, the efficient of the voltage of power P=I * DC/DC transducer * DC/DC transducer is available.For LED and digital electron device, the voltage that obtainable power P=I * digital electron device and LED have.

In order to describe, provide an example: under the state of not controlling, the current drain of audio amplifier 10 approximately is 0.8mA, and the current drain of digital electron device approximately is 4.2mA.It approximately is the constant current of 4.7mA that current feedback circuit 13 transmits.Like this under these specified conditions, the voltage that makes digital electron device is through the DC/DC transducer, will be more favourable but use of DC/DC transducer connected in series.Even, in other research, can find, about energy more advantageously,, guide all required voltages through the DC/DC transducer as shown in the block diagram of Fig. 1.

The conversion of the supply voltage of audio amplifier 10 in this case can cause the maximum available power of amplifier: P=4.7mA * 18V * 0.82=69mW.Voltage at audio amplifier 10 is U=P/I=69mW/0.8mA=55V like this.This voltage is to be much higher than the 24V voltage that phantom power unit 31 is transmitted in the power adaptation procedure.But owing on the film of carbon capsule 9, also produce polarizing voltage, the supply power voltage value of the actual audio amplifier 10 that obtains is a little less than this value, but still is much higher than the 24V voltage that can use when not having the DC/DC transducer.

Fig. 5 representes to be connected to the microphone 54 of a transmitter or a remote control unit 55.The Long-distance Control of important microphone parameters here is directly to pass through audio frequency cable, promptly takes place through circuit 1,2.Control unit 55 or is configured in its front preferably on frequency mixer.Microcontroller 35 control frequency modulators 36 with parameter control input end 34, its input have two cable conductors 1,2 of the FM signal of same level to audio frequency cable.FM signal is suppressed in input difference amplifier 42 as common-mode signal then.Simultaneously, the supply power voltage of phantom power unit 31 is provided to two cable conductors 1,2 through feed resistance 32,33.In a preferred embodiment, FM signal is provided for unique lead of audio frequency cable, promptly is not used in the lead 2 of sound signal.

In a preferred embodiment, FM signal is to be produced by FSK (frequency shift keying) or CPFSK (continuous phase FSK).Two kinds of modulation are methods known in the digital data transfer technology.In principle, also possibly utilize ASK (amplitude shift keying) or PSK (phase shift keying) modulation.But ASK more possibly be interfered, and the PSK modulation sees it is to be difficult to carry out from the viewpoint of circuit engineering.Compare with the application of known said method, under the situation about in microphone, using, key factor is that modulation signal must separate from an analog signal, sound signal.Even a FM signal feed-in is not intended for use the lead 2 of sound signal, the interference that two leads 1 of audio frequency cable, the capacitive coupling between 2 cause sound signal.Capacitive coupling depends on the structure and the length of audio frequency cable.Therefore, although control signal is known, it is difficult filtering interference.

In microphone; Fm voltage is through filter 37; Separate from sound signal like a band pass filter, the control information that is included in wherein is through control electronic device 39, estimates like a microcontroller or a CPLD (complex programmable logic equipment).Cable conductor 2 is to eliminate with the coupling between greatly through electric capacity 43.It is the front as a comparator 38 of voltage comparator that control electronic device 39 is connected to function.For example, the order of output through control electronic device 39 has arrived the power-supplying circuit 11 as seeing in Fig. 1 and 2, audio amplifier 10, and processor is controlled electronic device 39, A/D or D/

A converter

44,46 or the like.

At the frequency modulation of two audio lines 1,2 is in remote control unit 55, to carry out, remote control unit 55 preferably be positioned at mixture table near.In remote control unit 55, on the one hand, the rate of carrying must be on the direction of microphone 54, to apply, and on the other hand, on the direction of mixture table, all frequency modulation must be suppressed.Only the sound signal from microphone 54 must be transmitted.Simpler for the inhibition that makes frequency modulation, modulation is to carry out on both at the audio line with same level 1,2.In remote control unit 55, the result, FM signal shows as a common-mode signal of input difference amplifier 42, thereby is suitably suppressed as mode signal commonly used.In second modification of Long-distance Control, frequency modulation only occurs in the circuit that does not transmit sound signal, and promptly circuit 2.On the direction of mixture table, in this modification, FM signal can be eliminated through the filtering of low pass filter 41.The phantom power unit 31 that comprises feed resistance 32,33 and differential amplifier 42 and low pass filter there is no need as shown in Figure 5 being integrated in the remote control unit.For example, they also can provide in mixture table.

54 the transmission course, arrived control electronic device 39 for guaranteeing control signal reality from remote control unit 55 to microphone in control signal, latter's responsive control signal sends a data acknowledge message for remote control unit 55.Data-acknowledge message also can be a FM signal.The data-acknowledge message that is used for remote control function is not indispensable; But this is the reliability that cost has increased system with other electronic device.

Above-mentioned long-range control method is not limited to Electret Condencer Microphone certainly, because the similar microphone of any kind of can be operated through phantom power especially at the single power receiver of dynamic microphones.

Can be connected to the phantom power of any standard according to microphone of the present invention, and not influence microphone function.If phantom power comprises an equipment that is used for Long-distance Control, then microphone is remote controlled.Under what its situation in office, microphone can be operated by the switch that is directly installed on the microphone.

Fig. 6 representes that according to Electret Condencer Microphone of the present invention wherein the adjusting of polarizing voltage is to carry out through two-stage regulating and controlling loop.Here, second digit regulating loop 47 is on internal simulation regulating loop 48.As a result, on microphone capsule 9, can produce a polarizing voltage that be suitable for regulating, that avoid disturbing.

One preferably have control information, through cable conductor transmission, be also connected to phantom power unit 31 FM signals, arrive control electronic devices 39 through wave filter 37 and comparator 38.Detailed presentations according to the Long-distance Control of relevant microphone of the present invention provides in the above.Particularly also referring to Fig. 5.The control of control electronic device 39 also can be carried out through conditioning equipment or the operated device at microphone self.Also possible is that the control electronic device is connected to a radio or an infrared interface that is used for wireless transmission, or is connected to a cable interface.The desired value that obtains in the control signal of polarizing voltage is to be sent to analog regulation 48 by control electronic device 39 through D/A converter 46.Substitute D/A converter, also can use a pulse width modulation circuit (PWM).Although pwm circuit has lower switching rate, therefore their cheapnesss very are suitable for regulating the constant level in these transducers.Fig. 7 is an embodiment example, and expression control electronic device 39 for example is a microcontroller or a CPLD, how to react on analog regulation loop 48 with D/A converter or PWM46 one.Many analog regulation loop are known in the present art, understand the element that those skilled in the art select such regulating loop easily.Anticipate as shown in Figure 6, analog regulation loop 48 comprises a regulating circuit 56 and a voltage divider 49,50.The details of regulating circuit 56 or whole analog regulation loop 48 is to be illustrated among Fig. 7.

Analog regulation loop 48 preferably provides by having a power-supplying circuit 11 that is about the non-regulation voltage of 100-120V.The DC/DC transducer can be a type same as described above, or identical with shown in Fig. 1 and 2.Resistance 5 and 6 is the feed resistance in the microphone.They are used to remove the coupling between the output of power supply and audio amplifier 10 of microphone.Resistance 5 and 6 is identical in size, to keep the symmetry of circuit 1 and 2.

Certainly the invention is not restricted to the phantom power of Electret Condencer Microphone power supply.For example, the power supply of the single power receiver of Electret Condencer Microphone also can be provided by the battery that is arranged in microphone.

The desired value that provides by D/A converter or PWM46, or more precisely, the corrected value of polarizing voltage is to compare with actual value through operational amplifier 52.Desired value is to calculate according to the calibration data of in the manufacture process of microphone, measuring, and is programmed into the control electronic device.As a reference value of this calculating, can utilize an accurate reference voltage 45 on the lead or in printing test (print measurement) process, be programmed into a reference voltage controlling electronic device.For example, reference voltage 45 can be realized by logic power 24.Such logic power 24 is preferably presented by DC/DC transducer 11, and this is not illustrated among Fig. 7, but is illustrated in Fig. 1 and 2.

Be to suppress the interference effect of High-frequency Interference to analog regulation loop 48, a preferred embodiment provides a low pass filter 51 between the input of D/A converter or PWM46 and analog regulation loop 48, as shown in Fig. 7.The actual value that analog regulation loop 48 produces is absorbed through voltage divider 49,50, and is applied to the inverting input of operational amplifier 52 through an impedance transducer 53.Feedback circuit adds that impedance transducer is not included in the sketch map of Fig. 6.Simultaneously, this voltage also is added in the input of A/C transducer 44 of digital regulation loop 47.Consequent digital signal as feedback effect in control electronic device 39.As a result, outer digital regulation loop 47 is closed.In Fig. 7, voltage divider can absorb actual value by resistance 49,50 expressions through voltage divider.As shown in Fig. 7, A/D converter 44, control electronic device 39, and D/A converter 46 also can be integrated in the single parts.

As the output of analog regulation 48, polarizing voltage that can be adjusted, it is added to microphone capsule 9 through high-ohmic resistance 8.Calculate an adjusting and the needed correction voltage of polarizing voltage that avoid disturbing or corresponding correction factor can be corresponding to different set, this reflects specific sensitivity, steering characteristic, and ageing parameter; They also can be stored in the memory that provides of control electronic device 39, and can visit at any time.

These correction factors can be changed (in service department or through distributors, and also possibly be by the consumer for example) afterwards by the Long-distance Control with mute microphone (MIC).Except can be by possibly the proofreading and correct of microphone characteristic aging or that is formed by substituting of microphone capsule, the microphone that the consumer at scene is special be also tuning thereby be possible.

The invention is not restricted to these independent embodiment examples.Certainly, that also can expect is the microphone that has wherein merged whole or at least some foregoing circuits of foregoing circuit capable of using.For example, the Long-distance Control of the assembly of all remote-controllable can provide in microphone; Equally, power-supplying circuit 11 can provide the power supply of the power receiver of imagining in all microphones.

Claims

1. method that is used for the Long-distance Control of microphone; Wherein, microphone (54) is connected to remote control unit (55), and said microphone (54) comprises at least one microphone capsule (9); With from audio frequency amplifier (10), power-supplying circuit (11), processor, control electronic device (39), A/D and D/A converter (44; 46), at least one parts of selecting in the group of light-emitting diode display (25), and give microphone through two cable conductors (1,2) power supply of audio frequency cable by the phantom power unit (31) in the remote control unit (55); Be so-called phantom power supplied; It is characterized by, fm voltage as a control signal from said remote control unit (55) be applied in to carry out in said phantom power supplied said two cable conductors (1,2) at least one; And be applied to a control electronic device (39) of said microphone (54) subsequently, said control electronic device sends to independent said at least one parts according to said control signal with instruction.

2. the method for claim 1 is characterized in that, the carrier frequency that is used for said control signal is 100kHz.

3. like a described method in the claim 1 to 2, it is characterized in that audio signal is transmitted through one in said two cable conductors (1,2), said fm voltage is fed in said two cable conductors (1,2) another.

4. like a described method in the claim 1 to 2, it is characterized in that said fm voltage is applied in to two cable conductors (1,2) with same level, as a common-mode signal.

5. method as claimed in claim 3 is characterized in that, said fm voltage is separated with said audio signal by an input difference amplifier (42).

6. method as claimed in claim 3 is characterized in that, said fm voltage is separated with said audio signal by a low pass filter (41).

7. like a described method in the claim 1 to 2, it is characterized in that, the said control signal of response from said remote control unit (55) to said microphone (54), a data acknowledge message is sent to said remote control unit.

8. long-range control method as claimed in claim 7 is characterized in that, said data-acknowledge message also is a FM signal.

9. long-range control method as claimed in claim 1 is characterized in that, said control electronic device is microcontroller or CPLD.