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JPH0658698

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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 JPH0658698
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method for dynamically controlling the amplitude, velocity or acceleration of an oscillating
system such as an MFB (motional feedback) type speaker, vibrator or the like. The present
invention relates to the structure of an MFB type electromechanical vibration converter with an
improved power generation portion that generates a feedback voltage having an excellent
linearity.
[0002]
2. Description of the Related Art A typical structure of a conventional MFB type
electromechanical vibration converter will be described, for example, for an MFB speaker
illustrated in FIG. 5. In the front of a magnetic circuit 101 having a ring-shaped magnetic gap
101a. A frame 102 is fixed, and a cone-shaped diaphragm 105, to which a voice coil 103 is
coupled at the top, is vibratably attached to the inside of the frame 102. The voice coil 103 is
inserted into the magnetic gap 101a, and when an audio current flows through the voice coil
103, it acts on the magnetic flux in the magnetic gap 101a to generate a driving force to vibrate
the diaphragm 105.
[0003]
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A second magnetic circuit 106 of the same type as the magnetic circuit 101 is attached to the
back of the magnetic circuit 101 by means of a fixed member 111 or the like, and through holes
107 pass through the central magnetic poles of both magnetic circuits. It is formed. A connecting
rod 109, one end of which is fixed to the voice coil 103, is inserted into the through hole 107
and protrudes outside the second magnetic circuit 106. A detection coil 110 is attached to the
other end of the connecting rod 109. The detection coil 110 is inserted into the magnetic gap
106 a of the second magnetic circuit 106 to interlink with the magnetic flux, vibrates inside the
magnetic gap 106 a according to the vibration of the diaphragm 105, and generates the
vibration velocity of the diaphragm 105. Generate a proportional MFB voltage.
[0004]
The MFB voltage is converted into a voltage proportional to the amplitude and acceleration as
necessary, and is fed back to the speaker driving amplifier to control the speaker so as to obtain
a desired sound pressure frequency characteristic. When the transducer is a vibrator, instead of
the sound pressure frequency characteristic, the characteristic of the velocity, acceleration or
amplitude of the driven body is controlled depending on the application.
[0005]
As means for obtaining the MFB voltage, in addition to the above, for example, when the
diaphragm is conductive, electrodes are disposed in the vicinity of the diaphragm to
electrostatically detect a signal component proportional to the amplitude. Structure (not shown).
[0006]
In the conventional MFB type electromechanical vibration transducer having such a structure,
the MFB voltage and the induction component from the voice coil are mixed and the amplitude or
velocity of the vibration system can be obtained. In order to prevent the deterioration of the
linearity when detecting, it is necessary to separate the driving voice coil and the detecting
electrode or detecting coil, so the magnetic circuit and the movable as shown in FIG. 5. There is a
problem to be solved that both the material cost of the transducer and the assembly operation
cost are increased since two sets of electromechanical transducers consisting of coils must be
provided separately.
[0007]
Therefore, the present invention overcomes the disadvantages of the prior art, provides a
compensating coil to a transducer having a simple structure similar to that of the conventional
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transducer, and induces components from the voice coil included in the MFB voltage. It is an
object of the present invention to provide an MFB type electromechanical vibration transducer
that improves the linearity of detection by canceling the like, has a small number of parts, has
good workability, is inexpensive, and has high performance.
[0008]
SUMMARY OF THE INVENTION An MFB type electromechanical vibration converter according to
the present invention for achieving the above object will be described below with reference to
FIGS. 1 to 4 showing an embodiment.
[0009]
In the first embodiment shown in FIGS. 1 and 2, the magnetic circuit 1 having a ring-shaped
magnetic gap, the voice coil 2 and the voice coil 2 are closely wound on the voice coil 2, and the
vibration velocity information of the voice coil 2 is obtained. And a drive member 4 having a
detection coil 3 for obtaining an MFB voltage including the above and vibratably held in the
magnetic gap, and fixed to the magnetic circuit 1 and a mutual induction condition for the voice
coil 2 It consists of the induction compensation coil 5 disposed inside the magnetic gap so as to
approximate the detection coil 3 and cancels the induction voltage component mixed with the
vibration velocity information in the MFB voltage by the compensation output voltage of the
induction compensation coil 5 Thus, the detection coil 3 and the induction compensation coil 5
are coupled to each other, which is an MFB type electromechanical vibration converter.
[0010]
In the second invention shown in FIGS. 3 to 4, the magnetic circuit 1 having a ring-shaped
magnetic air gap, the voice coil 2 and the voice coil 2 are closely wound and then the vibration
velocity information of the voice coil 2 is obtained. And a detection coil 3 for obtaining an MFB
voltage, and an electromechanical vibration conversion unit 6 comprising a drive member 4
vibratably held inside the magnetic gap, and a magnetic field having a gap for coil attachment.
The circuit 7, the primary coil 8 inserted into and fixed to the gap, and the primary coil 8 are
closely wound to obtain an induced voltage from the primary coil 8 and mutual induction of the
induction compensation coil 5 with respect to the primary coil 8. A compensation output voltage
generation unit 10 comprising an induction compensation coil 5 whose condition is set to be
substantially equal to the mutual induction condition of the detection coil 3 with respect to the
voice coil 2; A detection coil 3 and an induction compensation coil 5 are coupled such that an
induced voltage component mixed with an oscillation velocity information to an FB voltage is
canceled by a compensation output voltage of the induction compensation coil 5. It is a
converter.
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[0011]
In the MFB type electromechanical vibration transducer having such a configuration, when a
voice current flows through the voice coil 2 and the drive member 4 vibrates, the detection coil
wound tightly on the voice coil 2 is produced. 3 also vibrates together, and a voltage in which a
voltage proportional to the vibration velocity of the driving member 4 and an induced voltage
component based on mutual induction are mixed is generated in the detection coil 3.
[0012]
On the other hand, in the first invention, since the inductive compensation coil 5 is fixed in the
magnetic gap (the pole wall in FIG. 1) in which the voice coil 2 and the detection coil 3 are
inserted, temporally It responds only to the AC magnetic flux due to the fluctuating voice current,
and as a result, generates only an induced voltage due to mutual induction with the voice coil 2.
Since detection coil 3 and induction compensation coil 5 are coupled to cancel the induction
voltage component mixed in the MFB voltage by the compensation output voltage of induction
compensation coil 5, the induction voltage component in detection coil 3 is induced It cancels out
of the voltage which is canceled by the compensation output voltage of the compensation coil 5
and disappears from the voltage fed back to the amplifier, the linearity of the vibration detection
is good, and an extremely stable MFB can be applied.
[0013]
Also, the transflector of such structure requires less parts as compared with the conventional
MFB type transducer, and the voice coil 2, detection coil 3 and induction compensation coil 5 are
all concentric. As it is placed in the same magnetic gap, it can be well known in the production
process as well as conventional conductive speakers and it does not require any special
operations, so quality control is easy and materials are also available. Both cost and cost can be
saved, and an inexpensive and stable converter of quality can be provided.
[0014]
In FIG. 6, the detection output voltage (dotted line) of the detection coil 3 of the converter of this
embodiment, the compensation output voltage of the induction compensation coil 5 (dashed
dotted line), and the detection coil 3 and the induction compensation coil 5 are reversed in phase.
The frequency characteristics and phase frequency characteristics of the feedback voltage (solid
line) obtained by
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[0015]
In the second aspect of the invention, the compensation output voltage generation unit 10 for
generating the compensation output voltage is wound closely on the primary coil 8 and the
primary coil 8 and induced voltage from the primary coil 8 Has a transformer structure in which
the induction compensation coil 5 for obtaining the above is fixed inside the magnetic gap of the
magnetic circuit 7, and the mutual induction condition of the induction compensation coil 5 with
respect to the primary coil 8 detects the voice coil 2 Since it is set equal to the mutual induction
condition of the coil 3, the cancellation of the induction voltage component in the detection coil 3
by the compensation output voltage is complete and stable MFB can be applied.
[0016]
In addition, since the magnetic gap of the portion of the electromechanical vibration conversion
unit can be narrower than in the case of the first invention, the conversion efficiency of the
converter can be increased.
[0017]
Furthermore, although the magnetic circuit 7 and the primary coil 8 constituting the
compensation output voltage generation unit 10 are additionally required structurally in
comparison with the first aspect of the invention, the compensation output voltage generation
unit 10 has a vibration. Since it has a simple and easy-to-assemble construction without parts and
the parts of the electromechanical vibration conversion unit 6 have the same structure as the
conventional converter, quality control is easy compared to the MFB converter of the
conventional example and the material is Both the cost and the construction cost can be saved,
and as in the first invention, an inexpensive and stable converter of quality can be provided.
[0018]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, the
embodiment of the present invention will be described in detail. FIG. 1 shows the cross section of
the first embodiment, and 1 is a magnetic circuit with a center pole 1a and a ring-shaped upper
portion. The plate 1b and the magnet 1c form a ring-shaped magnetic gap 1d having a radial
magnetic flux.
[0019]
Reference numeral 4 denotes a driving member for driving a driven body such as a diaphragm,
and the detection coil 3 is wound around the voice coil 2 and the voice coil 2 in close contact
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with the winding frame 4a. The respective coil portions are located inside the magnetic gap and
held so as to be able to vibrate by means of a center holder 12.
[0020]
In this embodiment, a cone-shaped diaphragm 11 for emitting acoustic radiation is attached to
the upper end of the driving member 4.
[0021]
An inductive compensation coil 5 for obtaining a compensation output voltage is fixed to the
inner peripheral portion of the upper plate 1b of the magnetic circuit 1 facing the magnetic air
gap 1d.
The induction compensation coil 5 is set such that mutual induction conditions for the voice coil
2 approximate the detection coil 3 in order to cancel the induction component from the voice coil
2 included in the MFB voltage generated in the detection coil 3. Ru.
In practice, if there is a coil wire length identical to that of the detection coil 3, there is no
practical difference.
[0022]
FIG. 2 is a connection diagram of the first embodiment, in which the voice coil 2 is connected to
the amplifier 13, the detection coil 3 and the induction compensation coil 5 are connected to be
opposite to each other, and the feedback circuit 14 is connected. It is fed back to the amplifier
13.
If necessary, the output levels of both coils can be finely adjusted to complete cancellation of the
induced voltage component (not shown).
A program source 15 is connected to the front stage of the amplifier 13.
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[0023]
FIG. 3 shows a cross-sectional view of the second embodiment, in which an electromechanical
vibration conversion unit 6 for driving a driven body and a compensation output voltage
generation unit 10 function as one set.
[0024]
The electromechanical vibration conversion unit 6 has a magnetic circuit in which a ring-shaped
magnetic gap 1d having a radial magnetic flux is formed by the center pole 1a, the ring-shaped
upper plate 1b and the magnet 1c as in the first invention. The detection coil 3 is wound closely
on the voice coil 2 and the voice coil 2 on the winding frame 4a, so that each of the coil parts is
inside the magnetic gap and can be vibrated by the center holder 12 And the driving member 4
held by the
[0025]
The compensation output voltage generation unit 10 is wound in close contact with the primary
coil 8 connected to the signal current source in parallel with the voice coil 2 and the primary coil
8 to obtain an induced voltage from the primary coil 8. The inductive compensation coil 5 and
the magnetic circuit 7 have a transformer structure fixed inside the magnetic gap.
Moreover, the mutual induction condition of the induction compensation coil 5 with respect to
the primary coil 8 needs to be set equal to the mutual induction condition of the detection coil 3
with respect to the voice coil 2, but in the embodiment of FIG. By setting the dimensions of the
circuit 1, the number of turns of the voice coil 2 and the primary coil 8, and the number of turns
of the detection coil 3 and the inductive compensation coil 5 respectively equal, the
electromechanical vibration conversion unit 6 and the compensation output voltage generation
unit 10 Makes it easy to manage the parts by making the respective part standards the same, and
makes the induced voltage component of the detection coil 3 and the compensation output
voltage of the induction compensation coil 5 equal to both the voltage level and the waveform,
and complete cancellation action It is considered to earn you.
In the figure, reference numeral 16 denotes a coupling member for coupling the magnetic
circuits of the two units.
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[0026]
FIG. 4 is a connection diagram of a second embodiment of the present invention, in which the
voice coil 2 and the primary coil 8 are connected in parallel to the amplifier 13 in the same
polarity and the detection coil 3 and the induction compensation coil 5 are In the same manner
as in the first aspect of the present invention, they are connected in reverse polarity to each
other and fed back to the amplifier 13 through the feedback circuit 14.
[0027]
As a modification of the second aspect of the invention, the compensation output voltage
generation unit 10 can be made into an approximately simple transformer structure.
In this case, it is desirable to equalize the magnetic properties of the magnetic circuit material so
as not to compromise the linearity of the vibration detection and to make the compensation
output voltage adjustable in the feedback circuit.
[0028]
Also in the second invention, as in the first invention embodiment shown in FIG. 1, a diaphragm
can be attached to the tip of the driving member 4 to make an MFB speaker, but the second
invention and the second invention Both of the first invention described above are a human body
mounting of health equipment instead of a diaphragm as a driven body.
[0029]
Furthermore, it is needless to say that the frequency characteristics such as the velocity,
amplitude or acceleration of the driven object can be controlled as required by processing the
MFB voltage with a differentiating circuit or an integrating circuit.
[0030]
Although the MFB type electromechanical vibration converter according to the present invention
has been described in detail based on the embodiment considered to be representative, the
embodiments of the MFB type electromechanical vibration converter according to the present
invention are the respective embodiments described above. The present invention is not limited
to the structure of the embodiment, but includes the constituent requirements described in the
above-mentioned utility model registration request, exhibits the effect according to the present
invention, and can be appropriately modified as long as it has the effects described below. It can
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be implemented.
[0031]
The MFB type electromechanical vibration converter according to the present invention has the
following effects.
[0032]
(1) The transformer of the present invention has a smaller number of parts as compared with the
conventional MFB type converter.
[0033]
(2) Since the voice coil and the detection coil are integrated, the shape is the same as a normal
voice coil, and both the coils and the induction compensation coil are disposed concentrically in
the same magnetic gap. Therefore, the manufacturing process may be the same work contents as
the conventional conductive type speaker, and since the special work is not required, the quality
control is easy, and the material cost and the construction cost can be saved.
[0034]
(3) The induced voltage in the MFB voltage generated in the detection coil is canceled by the
compensation output voltage generated in the inductive compensation coil fixed in the magnetic
gap, so the feedback MFB voltage is the vibration of the vibration system. It is information only.
Therefore, apply stable MFB
[0035]
(4) In the configuration of the second aspect, the configuration of the magnetic circuit and coils
of the compensation output voltage generation unit is completely the same as the magnetic
circuit and coils of the converter. The cancellation of the induced voltage component in the
detection coil by the compensation output voltage can be even more complete.
[0036]
Furthermore, in the second aspect of the invention, since the magnetic air gap of the portion of
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the electromechanical vibration conversion unit can be narrowed, the conversion efficiency of the
converter can be increased.
[0037]
With the above advantages, compared to the conventional MFB converter, quality control is easy,
material cost and construction cost can be saved, and an inexpensive, stable quality converter
can be provided. The
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