JP4711713B2 - Phantom power microphone power - Google Patents

Description

  The present invention is a microphone comprising at least one microphone capsule, at least one audio amplifier, and at least one additional power receiver, the processor, control electronics, AC / DC converter, DC / AC converter And a microphone selected from a group such as an LED display.

  The energy supply of the microphone is generated from the cable conductor of the audio cable, i.e. the pseudo-power unit via a so-called phantom power supply, the microphone is equipped with a power circuit for the individual power receiver, the power circuit is the cable conductor of the audio cable A control unit for converting the direct current transmitted through the alternating current into alternating current, a transformer connected to the control unit, and a power supply loop for each power receiver. The power loops are inductively coupled to the alternating current generated by the control unit and to each other using separate windings on the transformer.

  The power source of the microphone is conventionally provided by a power source using a mixer, for example. During phantom power, the feed voltage anode is supplied via two identical feeder resistors through the two cable conductors of the audio cable. A current return path is generated through a third conductor connected to pin 1 of the XLR plug. In order to effectively use the voltage supplied by the phantom power supply for the condenser microphone power supply, the microphone current consumption should be as low as possible to prevent an excessively large voltage drop at the feeder resistance. The maximum current consumption with a 48V condenser microphone is 10 mA. The phantom power here is standardized according to DIN EN61938 (formerly IEC 268).

  In order to generate a polarization voltage on a microphone membrane whose microphone membrane value is typically in the range of 20-100 volts dc, one mainly uses combinational circuit components or voltage converters. The remaining microphone electronics are usually powered by linear adjustment. The linear adjustment holds either the power feed voltage or the power current at a predetermined value. For microphones that consume little current, this type of power supply is appropriate. Linear adjustment becomes a problem when the power consumption in the microphone increases due to the use of processors, AC / DC converters, LED displays, and the like, for example. In this case, most of the energy available by the phantom power source is destroyed in the linear adjustment element. However, according to the standard, the phantom power supply is limited in its current by the feeder resistance, so the maximum power supply voltage for the audio amplifier decreases instantaneously due to the linear adjustment in the microphone, which reduces the maximum audio output voltage of the microphone. Result.

  An additional problem consists of generating polarization voltage. This voltage is usually supplied to the microphone membrane via a high ohmic resistance. Here, the required power is low. A voltage regulator that is highly efficient for generating this practically powerless polarization voltage is also difficult to construct.

  An additional problem relates to remote control of the microphone. There is an increasing need to use microphones to adjust or change important microphone parameters via remote control. These parameters include the polarization voltage on the membrane, the associated sensitivity of the condenser microphone, the directional characteristics of the microphone, the type of phantom power (12V, 24V or 48V), the product number, calibration data from the manufacture, and the signal And a filter that can be connected to the audio signal.

  DE 3 933 870 A1 discloses a method for remote control of microphone parameters such as directional characteristics, step sound filter or pre-attenuation. In this process, the power supply voltage transmitted to the cable conductor is adjusted in a manner whose amount represents control information for the microphone, for example via a remote control unit in the mixing table. On the microphone side, the supply voltage is disconnected and supplied to the evaluation circuit. The evaluation circuit generates a control signal as a function of the amount of power supply voltage. With this method of data transmission, only a small amount of control information can be transmitted to the microphone, and therefore only a few parameters can be remotely controlled at the microphone.

  An additional problem that has not been optimally solved so far relates to the generation of polarization voltage on the membrane of a condenser microphone. The level of polarization voltage is directly incorporated into the sensitivity level of the microphone capsule. As a result, it is also possible to adjust the sensitivity of the capacitor capsule with the aid of the polarization voltage. This is particularly advantageous in connection with the use of double membrane capsules. Because, in the case of separate power supplies for individual membranes with polarization voltage, these capsules allow not only sensitivity adjustment but also directional characteristic adjustment.

  A method of adjusting the polarization voltage with the aid of a fixed resistor or trim resistor is known. In this process, one-time adjustment of the polarization voltage occurs during microphone assembly. The directional characteristic is here determined once in advance, with a fixed resistance ratio. Using this method, as with the aging process, it is only possible with difficulty to compensate for tolerances in sensitivity caused by the assembly of the microphone capsule. For this, one needs to compensate for polarization voltage during sensitivity acoustic measurements in the assembled state of the microphone. Also, in the case of different directional characteristics, it is not possible to compensate for the sensitivity tolerance.

  US 4,541,112 discloses an electroacoustic transducer system for converting direct current to alternating current with an adjustable pulse generator. A transformer connected to the pulse generator allows the individual power receivers to be inductively disconnected. The power loop is inductively coupled to the alternating current generated by the pulse generator using a separate winding on the transformer. This document is incorporated by reference into this description.

  There is a need for a solution related to the power source of the microphone. The power made available by the phantom power is optimally used and converted to the operating voltage required for individual output receivers such as audio amplifiers, microphone capsules, processors, controllers, AC / DC converters, LED displays, and the like. Here, the objective is to be able to use as large a proportion of the power available by the phantom power supply that feeds the audio amplifier. In connection with these requirements, a serious disadvantage in the state-of-the-art technology is related to irregularities and variations in primary current capture, which forward these irregularities and make the overall microphone appropriate and efficient. May interfere with normal operation.

  In accordance with the present invention, these objects are achieved using a microphone as described above, characterized in that a power circuit is provided on the input side having a high ohm constant current source, whereby the circuit for the phantom power unit is , Forming a constant current sink.

  The use of a constant current source at the input of the DC / DC converter ensures that the primary constant current is captured. For the phantom power unit, the constant current source behaves like a constant current sink, which corresponds to a constant current source for the power circuit. Among other effects, a constant current source with as high an ohm level as possible simplifies the filtering of switching ripples generated during DC / AC conversion, thus it simultaneously prevents interference overlay on the audio signal.

  In an embodiment of the present invention, the microphone is characterized in that the constant current source is a transistor-LED current source. Using this constant current source, the LED is operated in the flow direction. As a result, a constant voltage is supplied to the LED, and such a voltage is also supplied to the series connection of the base-emitter diode of the transistor having the emitter resistance. This embodiment represents a sophisticated way to overcome the disadvantages of the state of the art in an inexpensive manner.

  In an embodiment of the invention, the microphone is characterized in that the constant current source comprises a degenerate transistor combined with two counters having an additional integrated constant current source.

  This circuit is preferred because it has better characteristics in terms of constant current and higher starting resistance.

  In this process, all voltages required for the power receiver described above are generated by a power supply circuit, for example, a DC / DC converter having the following characteristics. The power supply circuit is regulated or operated in such a way that there is current regulation to the pseudo current unit. Thus, the maximum possible power that the pseudo power unit can make available is always consumed by the microphone power circuit. The primary power consumption of the power supply circuit is constant. Therefore, the power supply circuit behaves like a constant current sink for the pseudo current unit. Individual power ropes for individual power receivers are disconnected in the power circuit using transformers to meet the different requirements of individual current receivers with as little power loss as possible: for example, low voltage and high current for digital electronics Similarly high voltage and low current for polarization voltage, modelet voltage and modelet current consumption for audio amplifier.

  The advantageous effect of the condenser microphone according to the invention is clear. Using the proposed power supply concept, the power made available by the pseudo power unit is optimally used. As a result, the microphone can be installed with new functions (eg, remote control, new operating concept, possibility of automatic compensation, etc.), while the maximum audio output voltage of the microphone remains the same. Generation of an essentially power-free polarization voltage occurs in practice as a secondary product with a simple additional winding on the transformer.

  An additional advantage is that, as a result of the use of as high an ohm level as possible, the switching ripple of the power circuit or DC / DC converter can be filtered very easily with a constant current source at the input of the power circuit. .

  Similar to frequency range modification, maximum audio output voltage modification, amplification modification or audio amplifier THD modification, polarization voltage change, thus sensitivity change, continuous change of directional characteristics of double membrane capsule As the possibility of adjustments in the microphone, such as changing control signals to the microprocessor storing the calibration data, increases, there is a need for a substantially higher data transfer rate to the microphone via remote control.

  In accordance with the present invention, these objects are achieved by a method for remote control of a microphone, where a frequency modulated voltage is provided as a control signal to at least one of two cable conductors, thereby also providing a phantom power supply. And a frequency-adjusted voltage on the microphone side transmits a command to an individual power receiver according to control electronics, eg a microcontroller or frequency-adjusted control signal (coupled programmable) Logic circuit).

In this way, the frequency adjusted voltage is overlaid on the phantom power supply voltage. Data transfer takes place, for example, from a transmitter arranged in a mixing table or a device in front of the mixing table via an audio line to a microphone. Here, the carrier frequency for FSK modulation is higher than the audio frequency range to be transmitted by the microphone, and by using a frequency modulated signal transmission, a substantially higher data transfer rate is achieved, as opposed to transmission at DC. Can be achieved. As a result, a large number of parameters can be transmitted using a certain protocol. The carrier frequency for the modulation is preferably around 100 kHz, which can be separated from the audio signal using a filter.

  To meet the need for low tolerances in the condenser microphone's polarization voltage (eg, ± 0.5 dB tolerance is required for sensitivity), flexible adjustment of the polarization voltage even in the assembled state of the microphone A solution to enable is needed.

  According to the invention, this is achieved by a condenser microphone, characterized in that the condenser microphone comprises at least one circuit for adjusting the polarization voltage, and the circuit for adjusting the polarization voltage has an unregulated voltage. An analog adjustment loop that is provided and a digital adjustment loop, wherein the digital adjustment loop provides the analog adjustment loop with a desired value for the polarization voltage calculated using control electronics, e.g., a correction factor. It is characterized in that it comprises a microcontroller or CPLD to be provided and for the feedback the output of the analog regulation loop is connected to the control electronics.

  In this process, the polarization voltage is adjusted by a voltage regulation loop integrated into the microphone. The desired value of the polarization voltage is preset in this circuit by the control electronics via a DC / AC converter. As a result, a fine stepwise adjustment of the polarization voltage can be performed. The desired value of the polarization voltage can also be transmitted to the control electronics by remote control. The tolerance of the resulting polarization voltage depends on the tolerance of the reference voltage source and the temperature characteristics.

  The adjustment of the polarization voltage via a digitally controlled adjustment loop in the microphone allows a very accurate, interference-resistant and remotely controllable adjustment of the polarization voltage of the condenser microphone. As a result, it is possible to achieve very small tolerance requirements for sensitivity and directional characteristics during the production of condenser microphones and in measurement technology inspection. Remotely controllable adjustment of the polarization voltage has the advantage that readjustment with a fixed or trim resistor is no longer necessary. This fact has a positive effect on cost. Compared to existing solutions of fixed set polarization voltage, the following additional possibilities arise in connection with the condenser microphone according to the invention.

  In the case of differently adjusted directional characteristics as a function of the individual characteristics of the double membrane capsule, different microphone sensitivities can be compensated and the required correction factors required to compensate the polarization voltage are stored. Can be done.

  In combination with remote control, as described above, for example, the polarization voltage can be calibrated during acoustic measurements with a closed microphone and the correction factor can be stored once more.

  It is of particular advantage to have the possibility of changing the polarization voltage of the microphone that can be remotely controlled, and thus changing the direction effect during operation. For example, a microphone acoustically follows an actor who is moving, for example, in an opera performance.

  The condenser microphone according to the present invention allows recalibration caused by aging of the microphone sensitivity without having to disassemble the microphone, which means cost savings for the consumer. During the microphone capsule exchange, the original sensitivity of the microphone can thus be readjusted later, ie after installation, by remote control.

  In the following, the invention is further described with reference to the figures.

FIG. 1 is a block diagram showing the main components of a microphone according to the present invention. The phantom power supply of the microphone shown in FIG. 5 is executed by the pseudo supply unit via feeder resistors (32, 33) of the same size. The feeder resistors (32, 33) are located behind the three-pole plug 4 (eg, XLR plug) in or in front of the mixing table. Such a phantom power supply is shown in FIG. Three phantom power sources are possible according to this standard. The relevant values of feeder resistance for 12-V, 24-V or 48-V power supplies are 680Ω, 1.2 kΩ or 6.8 kΩ, respectively. Line 1 and line 2 here represent the cable conductors supplied by the simulated supply unit, and line 3 represents the ground wire that is typically connected to the ground cable shield. Via an audio cable (ie via lines 1 and 2 and resistors 5 and 6) the pseudo power unit 31 is connected to the input of the power supply circuit 11 according to the invention. The capacitance 7 flattens the power supply voltage with respect to the ground. The resistors (5, 6) are feeder resistors in the microphone. They are used to disconnect the microphone power from the output of the audio amplifier 10. The feeder resistance of the microphone (5, 6) is assigned as an additional internal resistance of the pseudo power unit 31. Power adaptation exists when the internal resistance of the pseudo power unit is the same as the internal resistance of the power supply circuit 11 in the microphone. Therefore, in the case of power adjustment, half of the phantom power supply is the power supply voltage for the power supply circuit 11. This maximum power that can be generated by the pseudo power unit 31 is distributed via the power supply circuit 11 in the form of a DC / DC converter to all the energy consuming components in the microphone. Here excess power is available to the audio amplifier to achieve the maximum possible audio output voltage of the microphone. For different power supply voltages (standard 12V, 24V, 48V), the circuit can be designed in such a way that power regulation for different phantom power supplies occurs automatically. This task is then replaced by the control unit 12 described below.

  The power circuit 11 includes a power source 13, a control unit 12, and a transformer 14 connected to the control unit 12. The control unit 12 with the transformer 14 forms a circuit unit, where the DC voltage is converted into an AC voltage. In this case, the transformer is part of the oscillator generation circuit. Of course, the alternating current can also be generated by the control unit 12 which is independent of the transformer. The control unit 12 consists of an oscillation circuit that is independent of the transformer, which generates an alternating current. The transformer serves only the function of converting alternating current into individual output voltages.

  In a preferred embodiment, the alternating signal has a frequency in the range of 100 kHz to 130 kHz. The alternating signal can also oscillate freely. This represents the possibility of the simplest embodiment for such a circuit. The only important factor is that the frequency range of the AC signal must be outside the audio frequency range in order not to generate any interference to the audio signal, and the interference cannot be removed by simple filtering. In contrast, the frequency should not be too high. This is because in other cases, the degree of circuit efficiency decreases and transmission interference is expected.

  A further advantage of using a frequency of 100 kHz to 130 kHz is that this frequency can also be used as a cycle pulse for the control electronics 39 provided in the microphone. As a result, interference signals generated by digital techniques are minimized. This is because no additional mixed product is generated between the digital cycle time and the frequency of the DC / DC converter.

  The generated AC signal is supplied to the transformer 14. As a result of the individual windings on the transformer, separate current loops (15, 16, 17) are created to supply the individual components that consume energy. This decoupling allows simultaneous supply to consumers requiring high current consumption and low voltage, as well as consumers requiring high voltage and low current, with as little power loss as possible. The diodes (18, 19, 20) and capacitors (21, 22, 23) in the individual power supply loops (15, 16, 17) represent rectifier circuits that convert AC voltage to DC voltage. Of course, from the state of the art, more complex and more efficient rectifier circuits can be provided for individual power supply loops. The power supply loop 16 serves to supply a polarization voltage to the microphone capsule 9, and the polarization voltage is supplied to the microphone capsule 9 via the resistor 8.

  Of course, the present invention is not limited to condenser microphones. This is because any microphone, in particular a dynamic microphone, can be connected to the phantom power source. Individual power receivers are similarly supplied by the phantom power unit as shown in FIGS. However, in the case of dynamic microphones, no polarization voltage is required, and therefore no power supply loop is required.

Use of the constant current source 13 at the input of the DC / DC converter ensures the uptake of the primary constant current. For the pseudo power unit 31, the constant current source 13 behaves like a constant current sink, which represents a constant current source for the power supply circuit 11. Among other effects, the constant current source 13 having the highest possible ohmic level simplifies the filtering of switching ripples generated during DC / AC conversion, which at the same time prevents interference overlay on the audio signal. This type of electrical component is well known to those skilled in the art. An example of a state-of-the-art constant current source circuit is shown in FIGS. FIG. 3 shows a “transistor LED” constant current source with bipolar transistors. Using this constant current source, the LED operates in the flow direction. As a result, a constant voltage is supplied to the LED, and such a voltage is also supplied to a series connected base emitter diode of a transistor having an emitter resistance. Thus, the current supplied by this current source is I = (U _LED −U _bc ) / Re, where U _LED is the voltage drop across the LED, U _bc is the base emitter voltage and Re is Emitter resistance.

The circuit shown in FIG. 4 includes a constant current source having degenerate transistors (28, 29) combined with two counters with an additional integrated constant current source 30. This circuit is preferred because it has better characteristics in terms of constant current and higher starting resistance. At the primary resistance Rc, the current source 30 generates a voltage drop equal to the voltage drop _URc at the emitter resistance Re of the transistor 28. Here, the current of the constant current power generation is I = U _Rc / Re. Here, transistor 29 together with transistor 28 forms a degenerate system that ensures the same voltage drop across resistors Rc, Re. As a result, the current I of the current source is also kept constant. Therefore, the current of the current source 30 is smaller than the constant current finally flowing into the DC / DC converter 11 by 100 coefficients.

  Of course, other types of constant current sources may be provided, for example, current sources having reverse-operation amplifiers, Howland current sources, and the like.

  The power supply voltage generated by the power supply circuit 11 for the audio amplifier 10 is not controlled in the preferred embodiment. In the power supply loop 16 for the microphone capsule 9, regulation circuits (47, 48) are provided between the diode 18 and the resistor 8. The resistor 8 includes a digital adjustment circuit 47 and an analog adjustment circuit 48, and a polarization voltage is supplied to the microphone capsule 9. FIG. 6 together with FIG. 7 preferably shows an adjustment circuit (47, 48) capable of such remote control. The control signal required for adjusting the polarization voltage can be transmitted via at least one of the two cable conductors (1, 2). The detailed structure and method of operation of such a regulation circuit (47, 48) is further described below. In the remaining power loop, when current and voltage limits have not yet been provided to the components of the digital circuit, one can also supply a regulation circuit. In the preferred embodiment of FIGS. 1 and 2, no conditioning circuit is provided in the power supply loop 15 for the audio amplifier 10. As a result, the total power not used for other circuit components (eg, processor, control electronics 39, polarization voltage at microphone capsule 9, A / D converter 44, D / A converter 46, LED display 25). Is available for the audio amplifier 10. As a result, a high maximum audio output voltage can be achieved in the power saving design of audio amplifier 10 to achieve the high maximum audio output voltage. In principle, the power supply voltage for the audio amplifier 10 can also exceed the voltage available by the phantom power supply as a result. Thanks to the way in which the power supply circuit 11 operates, it is also possible to generate positive and negative power supply voltages for the audio amplifier 10. As a result, the audio amplifier 10 can also use ground as a natural potential. Therefore, the power supply voltage of audio amplifier 10 is in contrast to ground.

  In a more advantageous embodiment, a DC / DC converter 11 of the type described above operates with an effective rate of approximately 82%. Even in the most advantageous embodiment, power is lost in the DC / DC converter, so it is advantageous to couple what is consumed in series with the DC / DC converter, if possible. As a result of the use of the constant current source 13, for example, the logic power supply 24 is connected in series to the DC / DC converter 11 with consuming ones having constant current consumption, for example, control electronics 39, It is easy to make a fixed direct current available to the LED display 25, the A / D converter 44, and the D / A converter 46.

  A corresponding embodiment of the power supply circuit 11 is shown in FIG. Compared to FIG. 1, the difference is that only the polarization voltage and the voltage for the audio amplifier 10 are generated via the AC / AC converter. For example, other consuming devices such as a logic power supply 24 that makes available a predetermined fixed direct current to the control electronics 39 or LED display 25 are connected in series with the AC / AC converter. The AC / AC converter 11 connected in series with the digital power supply operates as an active load resistor. With an active load resistance, the energy used in this resistance is not converted to heat, but is converted to a usable power source for the polarization voltage on the audio amplifier 10 and the microphone capsule 9 in a large proportion.

  As shown in FIG. 2, a Zener diode is provided in connection with a logic power supply 24 that makes available a reference voltage or additional digital electronics, which is particularly suitable for stabilizing the voltage. ing. Through this diode 27, although not consumed, the current supplied by the constant current source 13 is released to ground. In principle, one can use any other constant current source or shunt regulator instead of a zener diode.

  The released power is a product of the current of the constant current source 13 and the voltage supplied to the power supply circuit 11. In the block diagram of FIG. 1, the entire voltage is supplied to the DC / DC converter 11, and all the voltages are generated via the DC / DC converter. In the block diagram 2, the voltage is divided into a first part supplied to the DC / DC converter 11 and a second part supplied to the LED 25 and the digital power supply. The DC / DC converter represents a pseudo resistance that is active with respect to the LED 25 or digital power supply. Although the current consumption of the digital power supply is not constant, the current I is kept constant by the current source 13, so that the surplus current that exists is dependent on the state of operation of the digital electronic device via the Zener diode 27. Should be released. For the power supply of the audio amplifier 10, power P = I × (voltage usable in the DC / DC converter) × (effective rate of the DC / DC converter) can be used.

  For illustration, an example is given. The current consumption of the audio amplifier 10 in the unregulated state is approximately 0.8 mA, and the current consumption of the digital electronic device is approximately 4.2 mA. The current source 13 supplies a constant current of approximately 4.7 mA. Thus, in this special case, it is more convenient to direct the voltage to the digital electronic device using a series connection to the DC / DC converter rather than via a DC / DC converter. Furthermore, in additional developments, it may be more convenient for the energy to derive all required voltages via a DC / DC converter, as in the solution shown in block diagram 1. I understand.

The conversion of the power supply voltage for the audio amplifier 10 in this case leads to the maximum power available to the amplifier, where P = 4.7 mA × 18 V × 0.82 = 69 mW. The voltage at the audio amplifier 10 is therefore U = P / I = 69 mW / 0.8 mA = 55V. This voltage is much higher than the 24V voltage supplied by the pseudo power unit 31 during power adaptation. However, since the polarization voltage is also generated on the membrane of the capsule 9, the value of the power supply voltage of the audio amplifier 10 actually reached is slightly lower than this value, but still without using a DC / DC converter. Much higher than 24V available.

FIG. 5 shows a microphone 54 connected to a transmitter or remote control unit 55. Here, the important microphone parameters of the remote control unit are generated directly via the audio cable, ie via lines 1 and 2. The control unit 55 is preferably on or in front of the mixer. A microcontroller 35 having a parameter control input 34 controls a frequency modulator 36 which supplies the same level of frequency modulated signal to the two cable conductors 1, 2 of the audio cable. The frequency modulated signal can then be suppressed as a common mode signal in the input-differential amplifier 42. At the same time, the power supply voltage of the pseudo power unit 31 is supplied to the two cable conductors 1 and 2 via the feeder resistors 32 and 33. In a preferred embodiment, the frequency modulated signal is fed to only one of the conductors of the audio cable, i.e. the conductor 2 that is not intended for the audio signal.

  In a preferred embodiment, the frequency modulated signal is generated by FSK (frequency shift keying) or CPFSK (continuous phase FSK). Both modulations are procedures known from digital data transmission technology. In principle, it is also possible to use ASK (Amplitude Shift Keying) or PSK (Phase Shift Keying). However, ASK is more susceptible to interference and PSK is more difficult to perform from a circuit technology perspective. In contrast to the known application of the above method, for use in a microphone, a significant factor is that the modulated signal must be separated from the analog signal, ie the audio signal. The capacitive coupling depends on the structure and length of the audio cable, even when a frequency-modulated signal is supplied only to the unintended conductor 2 for the audio signal. Therefore, filtering interference is difficult despite the fact that the control signal is known.

  In the microphone, the frequency-modulated voltage is separated from the audio signal using a filter 37 (eg, a bandpass filter), and the control information contained therein is controlled by a control electronics 39 (eg, a microcontroller or CPLD (coupled). It is evaluated using a programmable logic circuit)). The cable conductor 2 is disconnected from the ground via a capacitance. The control electronics 39 is connected in front of a comparator 38 that functions as a voltage comparator. For example, the command via the output of the control electronics 39 can be the power supply circuit 11, audio amplifier 10, processor, control electronics 39, A / D converter 44 or D / A converter 46 as shown in FIGS. Etc.

Frequency modulation on the two audio lines 1, 2 is performed in the remote control unit 55. The remote control unit 55 is preferably located near the mixing table. On the one hand, in the remote control unit 55, the carrier frequency should be supplied in the direction of the microphone 54, and on the other hand, all modulation frequencies in the direction of the mixing table must be suppressed. Only the audio signal emanating from the microphone 54 must be transmitted. In order to make the modulation frequency suppression simpler, the modulation is performed on both audio lines 1, 2 at the same level. As a result, in the remote control unit 55, the frequency modulated signal appears as a common mode signal for the input-to-differential amplifier 42, so that as a common mode signal, the frequency modulated signal is appropriately suppressed. Can be done. In a second variant of remote control, frequency modulation occurs only at the line that passes the audio signal (ie, line 2). In this variant, the frequency-modulated signal in the direction of the mixing table can be removed by filtering through the low-pass filter 41. The pseudo power unit 31 including the feeder resistors 32 and 33 as well as the differential amplifier 42 and the low-pass filter need not be integrated into the remote control unit, as shown in FIG. For example, they are also provided on a mixing table.

  During transmission of the control signal from the remote control unit 55 to the microphone 54, in order to ensure that the control signal actually reaches the control electronics 39, the microphone 54 receives the control signal and transmits the data recognition message remotely. Transmit to the control unit 55. The data recognition message can also be a frequency modulated signal. Data recognition messages for remote control functions are absolutely not necessary. However, it increases system reliability at the cost of additional electronic devices.

  Since the individual power receivers (especially dynamic microphones) of any microphone can be operated using a phantom power source, the above-described method of remote control is, of course, not limited to condenser microphones.

  FIG. 6 shows a condenser microphone according to the present invention. In this condenser microphone, the adjustment of the polarization voltage takes place using a two-stage control adjustment loop. Here, the second digital adjustment loop 47 is overlaid above the internal analog adjustment loop 48. As a result, it is possible to generate a well-tuned interference-free polarization voltage on the microphone capsule 9.

A preferred frequency modulated signal with control information transmitted via the cable conductor connected to the pseudo power unit 31 reaches the control electronics 39 via the filter 37 and the comparator 38. A detailed presentation regarding remote control of a microphone according to the present invention has already been provided above. In particular, see FIG. Control of the control electronics 39 can also take place via adjustment devices or operating elements on the microphone itself. It is also possible for the control electronics to be connected to a wireless, infrared interface for wireless transmission purposes, or a cable interface. The desired value obtained in the control signal for the polarization voltage is supplied by the control electronics 39 to the analog adjustment rope 48 via the D / A converter 46. Instead of a DC / AC converter, one can also use a pulse width modulation circuit (PWM). Although PWM circuits have a lower conversion rate, PWM circuits are inexpensive and are therefore very suitable for adjusting a constant level in these converters. FIG. 7 is an example embodiment and shows how control electronics (eg, a microcontroller or CPLD) with a D / A converter or PWM 46 act on the analog regulation loop 48. Many analog tuning loops are known in the state of the art, and it is easy for those skilled in the art to understand the present invention to select the size of such tuning loops. As schematically represented in FIG. 6, the analog regulation loop 48 includes a regulation circuit 56 and voltage dividers 49, 50. Details of the adjustment circuit or the entire analog adjustment rope 48 are shown in FIG.

  The analog regulation loop 48 is preferably provided by the power supply circuit 11 having an unregulated voltage of approximately 100V-120V. The DC / DC converter may be of the same type as described above or may be that represented in FIGS. The resistors 5 and 6 are feeder resistors in the microphone. The feeder resistor is used to disconnect the microphone power from the output of the audio amplifier 10. Resistors 5 and 6 are identical in size to preserve the symmetry of lines 1 and 2.

  The present invention is of course not limited to phantom power condenser microphones. For example, energy supply to individual power receivers can also be performed by a battery located in the microphone. The desired value provided by the D / A converter or PWM 46, more precisely the correction value for the polarization voltage, is compared via the operational amplifier 52 with the actual value. The desired value is calculated from calibration data measured during microphone manufacture and programmed into the control electronics. As a reference value for this calculation, one uses an accurate reference voltage 45 on the conductor or a reference voltage programmed into the control electronics during print measurements. The reference voltage 45 can be made available by the logic power supply 24, for example. Such a logic power supply 24, preferably supplied by a DC / DC converter 11 not shown in FIG. 7, is shown in FIGS.

  In order to suppress the undesired effects of high frequency interference on the analog adjustment loop 48, the preferred embodiment provides a low pass between the D / A converter or PWM 46 and the input of the analog adjustment rope 48, as shown in FIG. A filter 51 is provided. The actual value generated by the analog regulation loop 48 is picked up via the voltage divider and supplied to the reverse input of the operational amplifier 52 via the impedance converter 53. In addition to the impedance converter, the feedback line is not included in the schematic diagram of FIG. At the same time, this voltage is also supplied to the input of the A / D converter 44 of the digital regulation loop 47. The resulting digital signal is available to the control electronics 39 as feedback. As a result, the outer digital adjustment loop 47 is closed. In FIG. 7, the voltage divider from which the actual value is picked up via the voltage divider is represented by resistors 49, 50. As shown in FIG. 7, similar to the D / A converter 46, the A / D converter 44 and the control electronics 39 can also be integrated into a single component.

  As an output of the analog adjustment 48, one obtains a regulated polarization voltage that is fed to the microphone capsule 9 via a high ohmic resistance 8. The correction voltage or the corresponding correction factor required to calculate the adjusted and interference-free polarization voltage can correspond to different settings, which reflect certain sensitivity, guide characteristics and aging parameters To do. They can be stored in the memory provided by the control electronics 39 and can be requested at any time.

  The correction factor can later be changed by remote control with a closed microphone (e.g., Service Department, distributor, or consumer if possible). Thus, in addition to possible correction of microphone characteristics resulting from aging or replacement of microphone capsules, custom specific tuning in the microphone field is also possible.

  The invention is not limited to the examples of individual embodiments. Of course, it is conceivable to use a microphone in which all or at least some of the circuits described above are combined. For example, remote control for remotely controllable components can be provided at the microphone. The power supply circuit 11 can also supply all conceivable power receivers in the microphone.

1 shows a block diagram of a condenser microphone according to the present invention having a power circuit. FIG. 1 shows a block diagram of an embodiment of a condenser microphone according to the present invention having a power circuit. FIG. Fig. 2 shows a circuit diagram of a constant current source of a transistor LED according to the state of the art. Fig. 2 shows a circuit diagram of a constant current source with counter-coupled transistors according to the state of the art. It is a block diagram of the condenser microphone connected to the remote control unit. 1 is a block diagram of an integrated circuit capacitor microphone that adjusts polarization voltage. FIG. Fig. 2 shows a circuit with analog and digital adjustment loops for adjusting the polarization voltage.

Explanation of symbols

1, 2 Cable conductor 9 Microphone capsule 10 Audio amplifier 11 Power supply circuit 12 Control unit 13 Transformer 15, 16, 17 Power loop 25 LED display 28, 29 Transistor 31 Pseudo power unit 39 Control electronics 44 A / D converter 46 D / A converter 47 Digital adjustment loop (adjustment circuit)
48 Analog adjustment loop (adjustment circuit)

Claims (8)

A microphone comprising at least one microphone capsule (9), at least one audio amplifier (10), and at least one additional power receiver, the power receiver comprising a processor, control electronics (39) Selected from the group of A / D converter (44), D / A converter (46), LED display (25), etc., the energy supply of the microphone is the cable conductor (1,2) of the audio cable, ie , generated from the pseudo power unit (31) via a so-called phantom power, the microphone, a power supply circuit (11) for the individual power receiver, the power supply circuit (11), the cable conductor of the audio cable ( 1, 2) a control unit (1) for converting the direct current transmitted via alternating current into alternating current And 2), a transformer which is connected to the control unit (12) and (14), and a power supply loop (15, 16, 17) for said individual power receiver, the power supply loop, the transformer ( 14) Using a separate winding on the inductively coupled to the alternating current generated by the control unit (12) and to each other, the microphone inputs a high ohm constant current source (13) characterized by power supply circuit having a side (11) is provided, whereby, with respect to the pseudo power unit (31), the circuit forms a constant current sink, microphone.   The microphone according to claim 1, characterized in that the constant current source (13) is a transistor-LED current source. It said constant current source (13) comprises two transistors the counter is coupled (28, 29), the transistor (28, 29) is to have a additional integrated constant current source (30) The microphone according to claim 1, wherein: The microphone according to any one of claims 1 to 3, characterized in that the internal resistance of the power supply circuit (11) is the same as the internal resistance of the pseudo power unit (31) . At least one power receiver with constant current consumption , such as a processor, control electronics (39), A / D converter (44), D / A converter (46), LED display, etc. is connected to the power supply circuit (11 The microphone according to claim 1, wherein the microphone is connected in series. Wherein the power supply loop (16) relative to said microphone capsule (9), preferably remotely controllable adjusting circuit (47, 48), characterized in that provided for setting the polarization voltage, claim 1 To 5. The condenser microphone according to any one of 5 to 5. Supply voltage of the audio amplifier (10), characterized in that said more than pseudo voltage that will be supplied by the power unit, a microphone according to any of claims 1 to 6. Supply voltage of the audio amplifier (10), characterized in that it comprises a positive power supply voltage and the negative supply voltage is symmetrical with respect to ground, the microphone according to any of claims 1 to 7.

Images