JPH05111099

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DESCRIPTION JPH05111099
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
digital microphone device used for audio equipment and the like.
[0002]
2. Description of the Related Art In the case of a microphone device conventionally used for
audio equipment of this type, the outer peripheral end of a dome-shaped elastic diaphragm is
fixed on the main body of the device, and the lower surface inside the elastic diaphragm is fixed.
While a coil bobbin around which a coil is wound is integrally formed vertically, a permanent
magnet is disposed on the side of the apparatus main body facing the coil bobbin, and the inside
of the permanent magnet is changed according to a magnetic field change generated when the
coil bobbin vibrates. An electromotive force is generated in the coil wound around the coil
bobbin.
[0003]
By the way, in the case of such a conventional microphone device, the coil bobbin is produced in
response to a magnetic field change which occurs when a coil bobbin having a coil wound
around the lower surface inside the elastic diaphragm vibrates in a permanent magnet. The
external sound picked up by the microphone device is, for example, digital audio codec (DAT),
because it is structured to generate an electromotive force, that is, an analog voltage signal, in a
coil wound around the In the case of digital recording, the external sound signal picked up by the
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microphone device has to be temporarily recorded on a magnetic tape after being converted by
an analog / digital converter.
As a result, the use of the analog / digital converter not only increases the size of the entire
digital recording system, but also increases the cost. The present invention has been made to
solve such conventional problems, and with a simple configuration, converts an input external
sound into a digital external sound signal without using an analog / digital converter. It is an
object of the present invention to provide a digital microphone device capable of outputting
[0004]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention
provides a circuit board having a through hole, and a dome fixed on the circuit board so as to
surround the through hole. Elastic bulging body, a vertical body integrally formed on the lower
surface inside the elastic bulging body so as to be reciprocally movable in the through hole, and a
multilayer magnetizing body provided on the outer peripheral surface of the vertical body And a
plurality of magnetoresistive elements fixed at positions on the circuit board opposite to the
magnetized member. The plurality of magnetoresistive elements output, for example, an absolute
position signal indicating an absolute position of the elastic bulging body.
[0005]
According to the first aspect of the present invention, when the domed elastic bulging body fixed
so as to surround the through hole on the circuit board vibrates due to the sound pressure, the
elastic bulging body, Since the vertical body formed on the lower surface inside and the
multilayer magnetized body provided on the outer peripheral surface of the vertical body vibrate
in the same manner, the above-mentioned perpendicular from each magnetic resistance element
provided at a position facing this magnetized body A digital position signal (eg, an absolute
digital position signal indicative of an absolute vibration position of the magnet) is generated
corresponding to the vibration position of the body. As a result, it is possible to generate a digital
position signal corresponding to the vibration position of the elastic bulging body vibrated by the
sound pressure with a simple configuration.
[0006]
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DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described
based on the illustrated embodiments. FIG. 1 is a partially cutaway side view showing an
embodiment of a digital microphone device according to the present invention, FIG. 2 is an
exploded perspective view of the digital microphone device shown in FIG. 1, and FIG. 4 is a front
view showing FIG. 4 is a diagram showing the stored contents of a ROM for converting multi-bit
digital signals outputted from each magnetoresistance element side into corresponding absolute
position information, and FIG. 5 is a digital microphone according to this embodiment. It is a
figure which shows the circuit structure of the musical tone generator which used the apparatus.
[0007]
As shown in FIGS. 1 and 2, the digital microphone device 12 according to this embodiment
includes a circuit board 14 having a through hole 13 and a circuit board 14 fixed on the circuit
board 14 so as to surround the through hole 13. A rubber-like elastic bulging body 15, a
cylindrical vertical body 16 integrally formed on the lower surface of the elastic bulging body 15
so as to be reciprocally movable in the through hole 13, and the vertical body 16 It is composed
of a multilayer magnetized body 17 provided on the outer peripheral surface, and a plurality of
magnetoresistance elements 18 fixed at positions around the through hole 13 opposed to the
magnetized body 17. In the lower part of the elastic bulging body 15, a sheet portion 20 fixed by
an adhesive on the circuit board 14 is integrally formed. Further, on the circuit board 14, a
conductive pattern 21 for guiding the output signal output from each of the magnetic resistance
elements 18 to the electronic circuit unit (see FIG. 2) is formed.
[0008]
The magnetized member 17 may be formed by forming the perpendicular member 16 of a
magnetic material and directly forming a multilayered magnetized member 17 on the outer
peripheral surface by a known magnetization method. In this embodiment, however, it is thin The
cylindrical magnetized body 17 is fixed to the outer periphery of the vertical body 16. As shown
in FIG. 3 showing a part of the magnetized member 17, the magnetized member 17 corresponds
to the S pole and the N pole of the permanent magnet in correspondence with the arrangement
pattern representing the multi-bit digital signal shown in FIG. It is magnetized by For example, in
the case where the S pole and the N pole of the permanent magnet are magnetized to correspond
to an arrangement pattern representing a 16-bit digital signal of 4 bits, the S pole and the N pole
of the permanent magnet are described. As shown in FIG. 3, in the first row on the left, 16
alternately magnetized S and N poles are used in the first row on the left and in the second row
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in the first row on the left. , 8 alternately polarized S and N poles in half; in the third row, 4
alternately polarized S and N poles in half; 4th row on the far right In the above, two half of the
alternately magnetized S pole and N pole are arranged in half. Further, the south pole and the
north pole of the permanent magnet are arranged in 16 steps in the longitudinal direction. The
magnetizing areas of the S pole and the N pole can be made in micron order, as required.
[0009]
On the other hand, as described above, a large number of magnetoresistance elements 18 are
fixed to the positions on the circuit board 14 opposed to the magnetized positions of the large
number of S and N poles. Therefore, when the magnetized member 17 vibrates in the vertical
direction inside the through hole 13 according to the vibration of the elastic bulging body 15 due
to the sound pressure, the magnetized positions of the S pole and the N pole in multiple rows
follow the vibration of the magnetized member 17 Similarly, since it vibrates in the vertical
direction, the resistance value of the large number of magnetoresistance elements 18
sequentially changes in accordance with the change of the magnetic field according to the
vibration of the magnetized position of the S pole and N pole of these multiple rows. The output
signals of are simultaneously and sequentially output, and a large number of these output signals
are output as an absolute position signal to the CPU 22 through a waveform shaping circuit 23
described later.
[0010]
Next, the circuit configuration of a tone generation apparatus using the digital microphone
device according to this embodiment will be described based on FIG. That is, as shown in FIG. 5,
to the CPU (central processing unit) 22 which performs all the electronic control of the tone
generator 13, the waveform output signal outputted from the many magnetoresistance elements
18 as described above A plurality of waveform shaping circuits 23 for shaping the signals into
rectangular wave signals, and each rectangular wave signal (each of the rectangular wave signals
corresponds to a digital signal of many bits) simultaneously output from the waveform shaping
circuit 23 is sequentially A ROM 24 (see FIG. 4) for converting to corresponding absolute
position information and outputting it, a RAM 25 for sequentially storing absolute position
information sequentially outputted from the ROM 24, and an absolute position temporarily
stored in the RAM 25 A tone generator 26 controlled according to tone characteristic
specification information corresponding to information, and each rectangular wave signal (multibit digital signal) simultaneously output from the waveform shaping circuit 23 A digital / analog
converter 19 for converting the corresponding analog voltage signal is connected. Further, the
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ROM 24 receives a large number of rectangular wave signals (in FIG. 4, a, b, c, d indicate the
presence or absence of the rectangular wave signal from the four magnetoresistance elements
18), A large number of input rectangular wave signals (multi-bit digital signals) are converted
into corresponding absolute position information and output. The sound source 26 is connected
to an amplifier 27 for amplifying a musical tone signal output from the sound source 26, and the
amplifier 27 is connected to a speaker 28 for emitting the amplified musical tone signal to the
outside. There is.
[0011]
Next, the operation according to this embodiment will be described. Here, the case where the
waveform output signal is simultaneously output from the four magnetoresistance elements 18
according to the sound pressure from the outside will be described as an example. First, when
sound pressure is applied from the outside from the state shown in FIG. 1, the upper portion of
the elastic bulging body 15 gradually descends, and along with this, the vertical body 16 also
descends. Then, since the magnetized body 17 is provided on the outer peripheral surface of the
vertical body 16, the magnetized body 17 also descends in the same direction. Then, at each
descent position of the magnetized body 17, wave-shaped signals are simultaneously output in
different forms from the respective magnetoresistance elements 18 fixed on the circuit board 14
facing them. That is, before the sound pressure is applied, as in the arrangement of the
lowermost portion in FIG. 3, all the magnetic resistance elements 18 are opposed to the
magnetized body 17 at the position of the arrangement pattern of the S poles. When pressure
starts to be applied, the magnetic resistance elements 18 face each other at the position of the
arrangement pattern of the first row having N poles and the others all having S poles as in the
following arrangement from the lowermost part in FIG. In response to this, a wave-shaped signal
is output only from the magnetoresistance element 18 facing the N pole of the first column.
Furthermore, when sound pressure is applied, each magnetoresistive element 18 is located at the
position of the array pattern of the second row having N poles and all others having S poles, as in
the third array from the bottom in FIG. In response to this, a wave-shaped signal is output only
from the magnetoresistive element 18 facing the N pole of the second row. Subsequently, when
strong sound pressure is applied, the first and second rows have N poles and the third and fourth
rows have S, as in the arrangement from the bottom of FIG. When each magnetoresistive element
18 is shifted to the opposing state at the position of the arrangement pattern of the poles, in
response thereto, two magnetoresistive elements 18 facing the N pole of the first and second
columns. A wave-shaped signal is simultaneously output from.
[0012]
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As described above, when the elastic bulging body 15 vibrates in the vertical direction according
to the sound pressure from the outside and the magnetizing body 17 also vibrates in the same
direction according to this vibration, the output signal of the wave shape from the
magnetoresistive element 18 in different form It is simultaneously output sequentially. Then, the
output signal of each waveform is waveform-shaped into a rectangular wave signal by each
waveform shaping circuit 23 and then input to the CPU 22. Each waveform shaping signal
(corresponding to the 4-bit digital signal shown in FIG. 4) that has been input is converted into
corresponding absolute position information in the ROM 24 (step 6-1 in FIG. 6). The converted
absolute position information is written to the RAM 25 (step 6-2 in FIG. 6). The CPU 22
immediately reads the written absolute position information from the RAM 25 and sends tone
characteristic designation information corresponding to the read absolute position information to
the tone generator 26 (step 6-3 in FIG. 6). Therefore, based on the tone characteristic instruction
information corresponding to the above-mentioned absolute position information, a tone signal
having a corresponding volume, timbre, etc. is outputted from the sound source 26. The tone
signal is sequentially emitted as a tone from the speaker 28 through the amplifier 27. Therefore,
it is possible to sequentially emit a tone having a volume, tone, etc. according to the magnitude of
the sound pressure from the speaker 28 to the outside.
[0013]
Further, each waveform shaping signal (corresponding to the digital external sound signal of
multiple bits shown in FIG. 4) sequentially output from each waveform shaping circuit 23 is
sequentially converted by the digital / analog converter 19 into a corresponding analog external
sound signal. For example, the external sound input to the digital microphone device 12 is
directly converted into a multibit digital external sound signal without using an analog / digital
converter, and then this multibit digital external sound signal is analog The external sound signal
can be sequentially converted by the digital / analog converter 19, and the analog external sound
signal can be sequentially emitted from the speaker 28 in a form amplified by the amplifier 27.
[0014]
As apparent from the above description, according to the present invention, there is provided a
circuit board having a through hole, and a dome-like elasticity fixed on the circuit board so as to
surround the through hole. A bulging body, a vertical body integrally formed on the lower
surface inside the elastic bulging body so as to be reciprocally movable in the through hole, a
multilayer magnetizing body provided on the outer peripheral surface of the vertical body, and
the attachment Since the magnetic body and the plurality of magnetoresistive elements fixed to
the position on the circuit board opposed to each other are provided, the input external sound
can be directly transmitted without using the analog / digital converter with a simple
configuration. , Can be converted to a digital external sound signal and output.
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