close

Вход

Забыли?

вход по аккаунту

?

JP2005287051

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2005287051
PROBLEM TO BE SOLVED: To provide power that can be used by phantom power. SOLUTION:
The present invention comprises at least one microphone capsule, at least one audio amplifier
and at least one power receiver selected from the group of processors, control electronics, AC /
DC converters, DC / AC converters etc. With regard to the microphones provided, the energy
supply originates from the cable conductor of the audio cable, ie from the simulated power unit
via the so-called phantom power, the microphone comprises the power supply circuit for the
individual power receivers, the power supply circuit being It comprises a control unit for
converting direct current transmitted via the cable conductor into alternating current, a
transformer and a power supply loop for the individual power receivers. The power supply loops
are inductively coupled to each other and to each other generated by the control unit using
separate windings on the transformer. [Selected figure] Figure 2
Phantom Power Microphone Power Supply
[0001]
The invention relates to a microphone comprising at least one microphone capsule, at least one
audio amplifier and at least one additional power receiver, wherein the processor, the control
electronics, the AC / DC converter, the DC / AC converter , And a microphone selected from a
group such as an LED display.
[0002]
The energy supply of the microphone originates from the cable conductor of the audio cable, ie
01-05-2019
1
from the simulated power unit via the so-called phantom power, the microphone comprises the
power supply circuit for the individual power receivers, the power supply circuit the cable
conductor of the audio cable It comprises a control unit which converts the direct current
transmitted via it into an alternating current, a transformer connected to the control unit and a
power supply loop for the individual power receivers.
The power supply loops are inductively coupled to each other and to each other generated by the
control unit using separate windings on the transformer.
[0003]
Microphone power is conventionally provided, for example, by a power source using a mixer.
During phantom power, the anode of the feed voltage is supplied via two identical feeder
resistors via the two cable conductors of the audio cable. A current return occurs via 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 in the
feeder resistance. The maximum current consumption with a 48 V condenser microphone is 10
mA. The phantom power here is standardized according to DIN EN 61938 (formerly IEC 268).
[0004]
One typically uses combinational circuit components or voltage converters to generate the
polarization voltage on the microphone membrane, where the value of the microphone
membrane is typically in the range of 20 to 100 volts dc. The remaining microphone electronics
are usually powered by linear regulation. The linear adjustment holds either the supply voltage
or the supply current at a predetermined value. This type of power supply is appropriate for
microphones that consume little current. Linear regulation becomes a problem when power
consumption in the microphone is increased, for example by the use of a processor, AC / DC
converter, LED display, etc. In this case, most of the energy made available by the phantom
power is destroyed in the linear regulator. 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 is reduced instantaneously due to the linear adjustment at the
microphone, which reduces the maximum audio output voltage of the microphone Results.
01-05-2019
2
[0005]
An additional problem consists of the generation of the 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 the generation of this practically
powerless polarization voltage is also difficult to construct.
[0006]
An additional issue relates to the remote control of the microphone. There is an increasing need
to be able to adjust or change important microphone parameters via remote control using a
microphone. 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, and the calibration data from
the production signal. And a filter that may be connected to the audio signal.
[0007]
DE 3 933 870 A1 discloses a method of remote control of microphone parameters such as
directional characteristics, step sound filters or pre-attenuation. In this process, the power supply
voltage transmitted to the cable conductor is adjusted, for example via a remote control unit in
the mixing table, in such a way that its quantity represents control information for the
microphone. At 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
supply voltage. With this method of data transmission, only a small amount of control
information can be transmitted to the microphone, so also only two or three parameters can be
remotely controlled at the microphone.
[0008]
An additional, hitherto not optimally solved problem relates to polarization voltage generation on
the membrane of a condenser microphone. The level of polarization voltage is incorporated
directly into the level of sensitivity 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
01-05-2019
3
particularly advantageous in connection with the use of dual membrane capsules. Because, in the
case of separate power supplies of the individual membranes with polarization voltage, these
capsules allow not only adjustment of sensitivity but also adjustment of directional
characteristics.
[0009]
There is known a method of adjusting the polarization voltage with the aid of fixed resistance or
trim resistance. In this process, one-time adjustment of the polarization voltage occurs during
assembly of the microphone. The directional characteristics are now determined once, with a
fixed resistance ratio. With this method, as with the aging process, compensation for tolerance in
sensitivity caused by the assembly of the microphone capsule is only possible with difficulty. To
this end, one needs compensation of the polarization voltage during acoustic measurement of
sensitivity in the assembled state of the microphone. Also, for different directional characteristics,
it is not possible to compensate for sensitivity tolerances.
[0010]
U.S. Pat. No. 4,541,112 discloses an electro-acoustic transducer system for converting direct
current to alternating current having adjustable pulse generator. A transformer connected to the
pulse generator makes it possible to disconnect the individual power receivers inductively. The
power supply 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.
[0011]
There is a need for a solution in connection with the power supply of the microphone. The power
made available by the phantom power is optimally used and converted to the operating voltage
required for the individual output receivers such as audio amplifiers, microphone capsules,
processors, controllers, AC / DC converters, LED displays etc. Here, the aim is to be able to use as
large a proportion of the power available by the phantom power supply to the audio amplifier. In
connection with these requirements, a serious disadvantage in the state of the art relates to
irregularities and fluctuations in the acquisition of the primary current, which forward these
irregularities and make the overall microphone appropriate and efficient. Operation can be
01-05-2019
4
disturbed.
[0012]
According to the invention, these objects are achieved using a microphone as described above,
characterized in that the power supply circuit is provided at the input side with a high ohmic
constant current source, whereby the circuit for the phantom power supply unit is , Form a
constant current sink.
[0013]
The use of a constant current source at the input of the DC / DC converter ensures the capture of
the primary constant current.
For phantom power units, the constant current source behaves like a constant current sink,
which corresponds to a constant current source for the power supply circuit. Among other
effects, a constant current source with the highest possible ohmic level simplifies the filtering of
the switching ripples generated during DC / AC conversion, so that it simultaneously prevents
the overlaying of interference on the audio signal.
[0014]
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 of overcoming the
disadvantages of the state of the art in an inexpensive way.
[0015]
In an embodiment of the present invention, the microphone is characterized in that the constant
current source comprises a degenerate transistor coupled with two counters having an additional
integrated constant current source.
01-05-2019
5
[0016]
This circuit is preferred because of its better characteristics in terms of constant current and
higher starting resistance.
[0017]
In this process, all the voltages required for the above-mentioned power receiver are generated
by the power supply circuit, for example a DC / DC converter having the following
characteristics:
The power supply circuit is regulated or operated in a manner that there is current regulation to
the pseudo current unit.
Thus, the maximum power available to the simulated power unit is always consumed by the
microphone power circuit. The consumption of the primary power of the power supply circuit is
constant. Thus, the power supply circuit behaves like a constant current sink for the simulated
current unit. The individual power supply ropes for the individual power receivers are separated
in the power supply circuit by means of transformers and meet the different requirements of the
individual current receivers with as little power loss as possible: for example, low voltage and
high current for digital electronic devices Similarly, high voltage and low current to polarization
voltage, modelet voltage and modette current consumption to audio amplifier etc.
[0018]
The advantageous effect of the condenser microphone according to the invention is clear. With
the power supply concept presented, the power made available by the simulated power unit is
optimally used. As a result, the microphone can be mounted with new features (e.g. remote
control, new motion concept, possibility of auto-compensation etc), while the maximum audio
output voltage of the microphone remains the same. The generation of the essentially power-free
polarization voltage occurs in practice as a secondary product by simple additional windings on
the transformer.
[0019]
An additional advantage is that the switching ripple of the power supply circuit or the DC / DC
01-05-2019
6
converter can be filtered very easily with a constant current source at the input of the power
supply circuit as a result of using the highest possible ohmic level .
[0020]
As with the correction of the frequency range, the correction of the maximum audio output
voltage, the correction of the amplification or the THD of the audio amplifier, the change of the
polarization voltage and thus the change of the sensitivity, the continuous change of the
directional characteristics of the double membrane capsule There is a need for substantially
higher data transfer rates to the microphone via remote control, as the possibility of adjustment
at the microphone, such as changing the control signal to the microprocessor storing the
calibration data, increases.
[0021]
According to the invention, these objects are achieved by a method for remote control of a
microphone, wherein a frequency-modulated voltage is provided as a control signal to at least
one of the two cable conductors, whereby also a phantom power supply. , And the microphoneside frequency-regulated voltage transmits commands to the individual power receivers
according to the control electronics, eg microcontroller or frequency-controlled control signal
(combined programmable Logic circuit).
[0022]
In this way, the frequency adjusted voltage is overlaid on the supply voltage of the phantom
power supply.
Data transfer takes place, for example, from the transmitter placed in the mixing table or device
in front of the mixing table to the microphone via an audio line.
Here, the carrier frequency for FSK modulation has a substantially higher data rate, as opposed
to direct current transmission, by using a frequency modulated signal transmission that is higher
than the audio frequency range to be transmitted by the microphone. It can be achieved.
As a result, using a certain protocol, a large number of parameters may be sent. The carrier
frequency for modulation is preferably around 100 kHz, which can be separated from the audio
01-05-2019
7
signal using a filter.
[0023]
To meet the need for low tolerance (for example, ± 0.5 dB tolerance in terms of sensitivity) in
the polarization voltage of condenser microphones, flexible adjustment of polarization voltage
even in the assembled state of the microphone A solution that makes it possible is needed.
[0024]
According to the invention, this is achieved by means of a condenser microphone, characterized
in that the condenser microphone comprises at least one circuit for adjusting the polarization
voltage, wherein the circuit for adjusting the polarization voltage comprises an unregulated
voltage. The supplied analog adjustment loop and the digital adjustment loop, and the digital
adjustment loop controls the control electronics, eg the analog adjustment loop with the desired
value for the polarization voltage calculated with the correction factor. It is characterized in that
it comprises a microcontroller or CPLD to be provided, and characterized in that the output of
the analog regulation loop is connected to the control electronics for feedback.
[0025]
In this process, the polarization voltage is regulated by a voltage regulation loop integrated into
the microphone.
The desired value of the polarization voltage is preset in this circuit via the DC / AC converter by
the control electronics.
As a result, fine and gradual 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 polarization voltage obtained depends on the tolerance of
the reference voltage source and the temperature characteristics.
[0026]
Adjustment of the polarization voltage via the digitally controlled adjustment loop at the
01-05-2019
8
microphone enables 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 manufacturing
of the condenser microphone and in measurement technology testing. Remotely controllable
adjustment of the polarization voltage has the advantage that readjustment with fixed or trim
resistors is no longer necessary. This fact has a positive effect on cost. The following additional
possibilities arise in connection with the condenser microphone according to the invention, as
compared to the existing solution of fixed set polarization voltage.
[0027]
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 needed to compensate for the polarization
voltage are stored It can be done.
[0028]
In combination with the remote control, for example, the polarization voltage can be calibrated
during acoustic measurement with a closed loop microphone, as described above, and the
correction factor can be stored once more.
[0029]
It is particularly advantageous to have the possibility to change the polarization voltage of the
microphone, which can be remotely controlled, and thus to change the direction effect during
operation.
For example, a microphone acoustically follows a moving actor, for example, in an opera
performance.
[0030]
The condenser microphone according to the invention enables re-calibration caused by the aging
of the microphone sensitivity without having to disassemble the microphone, which means a cost
reduction for the consumer.
01-05-2019
9
During microphone capsule replacement, the original sensitivity of the microphone can thus be
readjusted later, that is to say after installation, by remote control.
[0031]
In the following, the invention is further described with reference to the figures.
[0032]
FIG. 1 is a block diagram showing the main components of a microphone according to the
invention.
The phantom power supply of the microphone shown in FIG. 5 is implemented by the simulated
supply unit via feeder resistors (32, 33) of the same size. Feeder resistors (32, 33) are placed
behind the three pole plug 4 (e.g. XLR plug) in the mixing table or in front of the mixing table.
Such phantom power is shown in FIG. Three phantom power supplies are possible according to
this standard. The associated values of feeder resistance for a 12-V, 24-V or 48-V power supply
are 680Ω, 1.2 kΩ or 6.8 kΩ respectively. Lines 1 and 2 here represent the cable conductors
supplied by the dummy supply unit, and line 3 represents the ground line which is usually
connected to the ground cable shield. The dummy power unit 31 is connected to the input of the
power supply circuit 11 according to the invention via the audio cable (i.e. via the lines 1, 2 and
the resistors 5, 6). 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 decouple the
microphone power supply from the output of the audio amplifier 10. The feeder resistances of
the microphones (5, 6) are assigned as additional internal resistances of the phantom power
supply 31. Power adaptation exists when the internal resistance of the pseudo power unit is
identical to the internal resistance of the power supply circuit 11 in the microphone. Thus, in the
case of power regulation, half of the phantom power is the power supply voltage for the power
supply circuit 11. This power, which is the largest that can be generated by the simulated power
unit 31, is distributed to all the energy consuming components in the microphone via the power
supply circuit 11, which is in the form of a DC / DC converter. Here, excess power is available to
the audio amplifier to achieve the largest possible audio output voltage of the microphone. For
different supply voltages (standard 12V, 24V, 48V), the circuit can be designed in such a way
that the power regulation for different phantom powers occurs automatically. Then this task is
replaced by the control unit 12 described below.
01-05-2019
10
[0033]
The power supply circuit 11 includes a power supply 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 direct voltage is converted into an alternating voltage. In this case,
the transformer is part of the oscillator generation circuit. Of course, alternating current may also
be generated by the control unit 12 which is independent of the transformer. The control unit 12
consists of an oscillating circuit that is independent of a transformer, which generates an
alternating current. Transformers only serve the function of converting alternating current into
individual output voltages.
[0034]
In a preferred embodiment, the alternating signal has a frequency in the range of 100 kHz to
130 kHz. AC signals 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
alternating current signal must be outside the audio frequency range in order not to generate
any interference to the audio signal, and the interference can not be removed by simple filtering.
On the other hand, the frequency should not be too high. This is because otherwise the degree of
efficiency of the circuit is reduced and transmission interference is expected.
[0035]
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 technology are minimized. The reason is that no
additional mixed product is generated between the digital cycle time and the frequency of the DC
/ DC converter.
[0036]
The generated alternating current signal is supplied to the transformer 14. As a result of the
separate windings on the transformer, separate current loops (15, 16, 17) are created to supply
01-05-2019
11
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
the capacitors (21, 22, 23) in the individual power supply loops (15, 16, 17) represent a rectifier
circuit which converts an alternating voltage into a direct voltage. Of course, from the state of the
art, more complex and more efficient rectification circuits can be provided for the 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.
[0037]
The invention is of course not limited to condenser microphones. Because any microphone, in
particular a dynamic microphone, can be connected to phantom power. Individual power
receivers are similarly supplied by the phantom power unit as shown in FIGS. 1 and 2. However,
in the case of a dynamic microphone, no polarization voltage is required, and thus no power
supply loop is required.
[0038]
The use of a constant current source 13 at the input of the DC / DC converter ensures the
capture of the primary constant current. For phantom power unit 31, constant current source 13
behaves like a constant current sink, which represents a constant current source for power
supply circuit 11. Among other effects, the constant current source 13 with the highest possible
ohmic level simplifies the filtering of the switching ripple generated during DC / AC conversion,
which at the same time prevents the overlaying of interference on the audio signal. Electrical
components of this type are well known to those skilled in the art. An example of a state-of-theart constant current source circuit is shown in FIGS. 3 and 4. 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 the base emitter diode of a series connection of transistors having an
emitter resistance. Thus, the current supplied by this current source is I = (ULED-Ubc) / Re,
where ULED is the voltage drop at the LED, Ubc is the base emitter voltage and Re is the emitter
resistance .
[0039]
01-05-2019
12
The circuit shown in FIG. 4 includes a constant current source having degenerate transistors (28,
29) coupled to two counters with an additional integrated constant current source 30. This
circuit is preferred to have better characteristics in terms of constant current and higher starting
resistance. With a primary resistance Rc, the current source 30 produces a voltage drop equal to
the voltage drop URc at the emitter resistance Re of the transistor 28. Here, the current of
constant current generation is I = URc / Re. Here, the transistor 29 together with the transistor
28 form a degeneration system which ensures the same voltage drop at the 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 by a factor of 100 than the constant current finally flowing into the
DC / DC converter 11.
[0040]
Of course, other types of constant current sources may also be provided, such as current sources
with reverse operating amplifiers, Howland current sources, etc.
[0041]
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, a regulation circuit (47, 48) is
provided between the diode 18 and the resistor 8. The resistor 8 comprises a digital adjustment
circuit 47 and an analog adjustment circuit 48, the polarization voltage being supplied to the
microphone capsule 9. FIG. 6 as well as FIG. 7 preferably show a conditioning circuit (47, 48)
capable of such remote control. The control signals required to adjust 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 conditioning circuit (47, 48) are further described below. In the
remaining power supply loop, one may also supply the regulation circuit when current and
voltage limits are not yet provided to the components of the digital 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, other circuit components (e.g., processor, control electronics
39, polarization voltage at the microphone capsule 9, A / D converter 44, D / A converter 46,
LED display 25) overall power not used Are available to the audio amplifier 10. As a result, a high
maximum audio output voltage can be achieved in the power saving design of the audio amplifier
10 to achieve the high maximum audio output voltage. In principle, the supply voltage for the
01-05-2019
13
audio amplifier 10 may also result in exceeding the voltage available by the phantom power
supply. Thanks to the manner of operation of the power supply circuit 11, it is also possible to
generate positive and negative power supply voltages for the audio amplifier 10. As a result,
audio amplifier 10 may also use ground as a natural potential. Thus, the power supply voltage of
the audio amplifier 10 is in contrast to ground.
[0042]
In a more advantageous embodiment, a DC / DC converter 11 of the type described above
operates with an efficiency of approximately 82%. Even in the most advantageous embodiments,
power is dissipated in the DC / DC converter, so it is advantageous to series couple what it
consumes to the DC / DC converter, if possible. As a result of the use of the constant current
source 13, for example, the logic power supplies 24 which consume constant current
consumption are connected to one another and connected in series to the DC / DC converter 11,
eg control electronics 39, It is easily possible to make fixed DC current available to the LED
display 25, the A / D converter 44 and the D / A converter 46.
[0043]
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 things, such as a logic power
supply 24 to make the predetermined fixed direct current available to the control electronics 39
or the LED display 25 are serially connected to the AC / AC converter. The AC / AC converter 11
connected in series to the digital power supply operates as an active load resistor. With an active
load resistor, the energy used in this resistor is not converted to heat, but at a large rate to an
available power source for the polarization voltage on the audio amplifier 10 and the microphone
capsule 9.
[0044]
As shown in FIG. 2, a zener diode is provided in connection with the logic power supply 24 which
makes available a reference voltage or additional digital electronic devices, which are particularly
suitable for stabilizing the voltage. ing. Through this diode 27, the current which is not consumed
but is supplied by the constant current source 13 is released to the ground. In principle, one may
01-05-2019
14
use any other constant current source or shunt regulator instead of a zener diode.
[0045]
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 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 an active pseudo-resistor for 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, depending on the state of operation of the digital
electronic device, the excess current present is via the zener diode 27. Should be released. For
the power supply of the audio amplifier 10, power P = I × (voltage available to DC / DC
converter) × (effective ratio of DC / DC converter) is available.
[0046]
An example is given for illustration. 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 about 4.7
mA. Thus, in this particular 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 the DC / DC
converter. Furthermore, in an additional development, it is more convenient to derive all the
required voltages via a DC / DC converter, like the solution shown in block diagram 1 in terms of
energy I understand.
[0047]
The conversion of the supply voltage to the audio amplifier 10 in this case leads to the maximum
value of the 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 voltage of 24 V supplied by phantom 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
01-05-2019
15
slightly lower than this value, but still without using the DC / DC converter Very high than 24V
available.
[0048]
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 the lines 1 and 2. The control unit 55 is preferably located on or in front of the
mixer. A microcontroller 35 with 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 may then be suppressed as a common mode
signal at the input-differential amplifier 42. At the same time, the supply voltage of the pseudocurrent unit 31 is supplied to the two cable conductors 1, 2 via the feeder resistors 32, 33. In a
preferred embodiment, the frequency modulated signal is supplied to only one of the conductors
of the audio cable, ie the conductor 2 for which the audio signal is not intended.
[0049]
In a preferred embodiment, the frequency modulated signal is generated by FSK (frequency shift
keying) or by 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 implement from a circuit technology point of view. In contrast to the known
applications of the above-described method, a critical factor for use in microphones 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 the frequencymodulated signal is only supplied to the conductor 2 which is not intended for the audio signal.
Thus, filtering the interference is difficult despite the fact that the control signal is known.
[0050]
In the microphone, the frequency-modulated voltage is separated from the audio signal by means
of a filter 37 (for example a band pass filter) and the control information contained therein is a
control electronics 39 (for example a microcontroller or CPLD (combined Programmable logic
circuits)). The cable conductor 2 is disconnected from the ground via the capacitance. The
01-05-2019
16
control electronics 39 are connected in front of a comparator 38 which functions as a voltage
comparator. For example, a command via the output of the control electronics 39 may be as
shown in FIGS. 1 and 2 as a power supply circuit 11, an audio amplifier 10, a processor, a control
electronics 39, an A / D converter 44 or a D / A converter 46. To reach etc.
[0051]
The 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 towards the microphone 54, on
the other hand, all modulation frequencies in the direction of the mixing table have to be
suppressed. Only the audio signal coming out of the microphone 54 has to be transmitted. In
order to make modulation frequency suppression simpler, modulation is performed on both
audio lines 1 and 2 at the same level. As a result, in the remote control unit 55, the frequencymodulated signal appears as a common mode signal to the input-differential amplifier 42, so that
the frequency-modulated signal is properly suppressed as a common mode signal. It can be done.
In a second variant of remote control, frequency modulation occurs only on the line through
which the audio signal passes (i.e. line 2). In this variant, in the direction of the mixing table, the
frequency-modulated signal can be removed by filtering through a low pass filter 41. The
phantom power unit 31 including the feeder resistors 32, 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 to the mixing table.
[0052]
During the transmission of the control signal from the remote control unit 55 to the microphone
54, the microphone 54 receives the control signal in order to ensure that the control signal
actually reaches the control electronics 39, and remotes the data recognition message. It
transmits to the control unit 55. The data recognition message may also be a frequency
modulated signal. Data recognition messages for remote control functions are absolutely not
necessary. However, it adds to the reliability of the system at the cost of additional electronics.
[0053]
The above-described method of remote control is, of course, not limited to condenser
microphones, as the individual power receivers of any microphones (especially dynamic
microphones) can be operated using phantom power.
01-05-2019
17
[0054]
FIG. 6 shows a condenser microphone according to the invention.
In this condenser microphone, regulation of the polarization voltage takes place using a control
regulation loop of two-stage operation. Here, the second digital adjustment loop 47 is overlaid
over the internal analog adjustment loop 48. As a result, it becomes possible to generate a welltuned, interference-free polarization voltage on the microphone capsule 9.
[0055]
Via a cable conductor connected to the phantom power supply unit 31, the preferred frequencymodulated signal with the control information to be transmitted reaches the control electronics
39 via the filter 37 and the comparator 38. A detailed presentation on the remote control of the
microphone according to the invention has already been provided above. See also, in particular,
FIG. The control of the control electronics 39 can also take place via an adjustment device or an
operating element on the microphone itself. It is also possible that the control electronics are
connected to a radio, an 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 via the D / A converter 46 to the analog tuning rope 48. Instead of
a DC / AC converter, one may also use a pulse width modulation circuit (PWM). Although PWM
circuits have lower conversion rates, PWM circuits are less expensive and, thus, are well suited
for adjusting a constant level in these converters. FIG. 7 is an example embodiment and shows
how D / A converter or control electronics (e.g. microcontroller or CPLD) with PWM 46 act on
the analog conditioning loop 48. FIG. Many analog tuning loops are known in the state of the art
and it is easy to select such tuning loop sizes for those skilled in the art who understand the
present invention. As schematically represented in FIG. 6, the analog regulation loop 48
comprises a regulation circuit 56 and voltage dividers 49, 50. Details of the tuning circuit or the
entire analog tuning rope 48 are shown in FIG.
[0056]
The analog regulation loop 48 is preferably supplied by a power supply circuit 11 having an
01-05-2019
18
unregulated voltage of approximately 100V to 120V. The DC / DC converter may be of the same
type as described above or may be as represented in FIGS. 1 and 2. Resistors 5, 6 are feeder
resistors in the microphone. Feeder resistors are used to decouple the microphone power supply
from the output of the audio amplifier 10. The resistors 5, 6 are identical in size to maintain the
symmetry of the lines 1 and 2.
[0057]
The invention is of course not limited to phantom powered condenser microphones. For example,
the energy supply to the individual power receivers can also be carried out by a battery located
in the microphone. The desired value, more precisely the correction value for the polarization
voltage, provided by the D / A converter or PWM 46 is compared via the operational amplifier
52 to the actual value. The desired values are calculated from calibration data measured during
manufacture of the microphone and programmed into the control electronics. As a reference
value for this calculation, one uses the accurate reference voltage 45 on the conductor or the
reference voltage programmed into the control electronics during the printing measurement. The
reference voltage 45 may be available, for example, by the logic power supply 24. Such a logic
power supply 24 preferably supplied by a DC / DC converter 11 not shown in FIG. 7 is shown in
FIGS. 1 and 2.
[0058]
In order to suppress the unwanted effects of high frequency interference on the analog tuning
loop 48, the preferred embodiment is a low pass between the D / A converter or PWM 46 and
the input of the analog tuning rope 48, as shown in FIG. A filter 51 is provided. The actual value
produced by the analog regulation loop 48 is picked up via the voltage divider and fed via the
impedance converter 53 to the inverting input of the operational amplifier 52. Feedback lines in
addition to the impedance converter are not included in the schematic 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, via the voltage divider, the voltage
divider from which the actual value is picked up is represented by the resistors 49, 50. As shown
in FIG. 7, like the D / A converter 46, the A / D converter 44, the control electronics 39 may also
be integrated into a single component.
[0059]
01-05-2019
19
As the output of the analog adjustment 48, one obtains a regulated polarization voltage which is
supplied to the microphone capsule 9 via a high ohmic resistor 8. The correction voltage or the
corresponding correction factor needed to calculate an adjusted and interference-free
polarization voltage may correspond to different settings, which reflect certain sensitivities, guide
characteristics, aging parameters Do. They can be stored in the memory provided to the control
electronics 39 and can be determined at any time.
[0060]
The correction factor may be changed later by remote control with a closed circuit microphone
(e.g., of the Service Department, distributor, or possibly the consumer). Thus, in addition to the
possible correction of the microphone characteristics resulting from the aging or replacement of
the microphone capsule, custom specific tuning in the field of the microphone is also possible.
[0061]
The invention is not limited to the examples of the individual embodiments. Of course, it is
conceivable to use a microphone in which all or at least some of the circuits mentioned above are
combined. For example, remote control to remotely controllable components may be provided at
the microphone. Also, the power supply circuit 11 may supply all possible power receivers in the
microphone.
[0062]
Fig. 1 shows a block diagram of a condenser microphone according to the invention with a power
supply circuit. Fig. 1 shows a block diagram of an embodiment of a condenser microphone
according to the invention having a power supply circuit. FIG. 1 shows a circuit diagram of a
constant current source of a transistor LED according to the state of the art. FIG. 1 shows a
schematic of a constant current source with counter-coupled transistors according to the state of
the art. FIG. 5 is a block diagram of a condenser microphone connected to a remote control unit.
FIG. 5 is a block diagram of an integrated circuit capacitor microphone for adjusting polarization
voltage. Fig. 2 shows a circuit with analog and digital adjustment loops, which adjust the
polarization voltage.
01-05-2019
20
Explanation of sign
[0063]
DESCRIPTION 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 Phantom power unit 39 Control electronic device 44 A / D converter 46 D / A
converter 47 Digital adjustment loop (adjustment circuit) 48 Analog adjustment loop (adjustment
circuit)
01-05-2019
21
Документ
Категория
Без категории
Просмотров
0
Размер файла
38 Кб
Теги
jp2005287051
1/--страниц
Пожаловаться на содержимое документа