JPH09298794

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DESCRIPTION JPH09298794
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone, and more particularly, it is possible to control resonance without separately using a
component for acoustic resistance, and to improve the sensitivity of high-pitched range and to
reduce the noise level. The present invention relates to a microphone that can be set to a value
and has few design restrictions.
[0002]
2. Description of the Related Art A conventional microphone 40 is shown in FIG. As shown in FIG.
4A, in the microphone 40, the microphone unit 42 is accommodated in a substantially cylindrical
case 41, and between the end of the case 41 (left end in the figure) and the front surface of the
microphone unit 42. The resonator unit 43 is provided on the In the microphone 40, the
resonator 44 is attached to the end of the case 41 in order to set the resonance frequency to a
desired value, and the acoustic resistance 45 in the resonance unit 43 in order to set the
resonance sharpness to a desired value. Is arranged.
[0003]
The resonator 44 is formed in a substantially deep dish shape for closing the end of the case 41,
and is provided with an opening 46 through which a sound wave can be introduced into the
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resonance portion 43. The resonator 44 is formed such that the resonance frequency of the
microphone 40 has a desired value, in other words, the resonance unit 43 has a desired acoustic
capacity. On the other hand, the acoustic resistance 45 is made of, for example, a sponge, and is
embedded in the acoustic capacitance portion of the resonance portion 43 set by the resonator
44 described above, and pressed and fixed to the front surface of the microphone unit 42 by the
resonator 44. The acoustic resistance 45 sets the resonance sharpness of the microphone to a
desired value, and serves as an acoustic series resistance in the resonance unit 43 to control the
resonance (see FIG. 4B).
[0004]
However, in the above-described microphone 40, the high band sensitivity is lowered as shown in
FIG. 5 because the resonator 43 and the acoustic resistor 45 constitute a low pass filter for high
frequencies. There is a problem of In addition, the above-described microphone 40 needs to have
an acoustic resistor 45 separately disposed in the acoustic capacitance in order to control
resonance, which causes a problem that the number of parts increases and the assembly
operation becomes complicated. Furthermore, in the case where the microphone unit 42 of the
microphone 40 is unidirectional, the directivity of the microphone 40 may be largely changed if
the large acoustic resistance 45 is used. Therefore, the microphone 40 needs to consider these
cases in design, and has a problem that it is difficult to obtain a desired appearance. The present
invention has been made to solve these conventional problems, and its object is to control
resonance without separately using a component for acoustic resistance, and to improve the
sensitivity of high frequency range. SUMMARY OF THE INVENTION An object of the present
invention is to provide a microphone which can be set to a desired value without deterioration
and with less design restrictions.
[0005]
SUMMARY OF THE INVENTION In order to achieve the above object, the invention described in
claim 1 of the present invention is a microphone unit housed in a cylindrical case and provided
on the front surface of the microphone unit In a microphone including a resonance unit, a first
acoustic capacity mainly determining a resonance frequency and a second acoustic capacity
mainly determining resonance sharpness are provided in the resonance section, and the first
acoustic capacity and the second acoustic capacity are provided. The capacitances are arranged
in parallel along a direction intersecting the traveling direction of the sound waves, and the
second acoustic capacitance can be communicated only with the first acoustic capacitance.
[0006]
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In this case, as the second acoustic capacity and the first acoustic capacity, for example, a
cylindrical wall extending along the traveling direction of the sound wave is inserted in the
resonance portion, and the inner circumferential space and the outer circumferential space of
this wall are One of them may be a first acoustic capacity, and the other may be a second
acoustic capacity.
Then, the second acoustic capacitance may close the opening side of the resonance portion and
be able to communicate only with the first acoustic capacitance through the communication hole
provided in the wall portion. At this time, the cylindrical wall portion may be arranged coaxially
with the case, or may be eccentrically arranged with respect to the axis of the case. In addition,
the communication holes provided in the wall may be appropriately formed at any places on the
circumferential surface of the wall, or a gap formed between the end of the wall and the front
surface of the microphone unit is adopted. May be And as a wall part, it may be provided in flat
form extended along the direction of movement of a sound wave, X shape, etc., and a resonant
part may be divided into two or more plurality.
[0007]
In the invention described in claim 1 of the present invention, the communication hole provided
in the wall portion becomes an acoustic impedance between the first acoustic capacity and the
second acoustic capacity, and the resonance of the sound wave traveling in the first acoustic
capacity Is controlled by this acoustic impedance and the acoustic impedance of the second
acoustic consideration y. Therefore, in the invention described in claim 1, the need for the
acoustic resistance material as in the prior art is eliminated in order to control the resonance, and
the reduction of the component parts and the simplification of the assembly process can be
obtained. Become. In the first aspect of the invention, since the first acoustic capacity and the
second acoustic capacity are arranged in parallel along the direction intersecting the traveling
direction of the sound wave, the resonance of the sound wave is achieved by the parallel acoustic
circuit. It is controlled. That is, in the invention described in claim 1, compared with the
conventional case where resonance is controlled by the series resistance formed by arranging the
acoustic resistance material in the resonance portion, the high band sensitivity higher than the
resonance frequency is obtained. It will not decline. Furthermore, in the invention described in
claim 1, since the resonance of the sound wave is controlled by the parallel acoustic circuit, the
acoustic resistance value is increased as in the conventional series resistance even when the
microphone unit is unidirectional. There will be little change in directivity. That is, in the
invention described in claim 1, design restrictions are alleviated as compared with the prior art,
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and the object is achieved by these.
[0008]
Further, in the invention described in claim 2, the main air chamber for setting the first acoustic
capacity and the auxiliary air chamber for setting the second acoustic capacity are sectioned by
the wall portion provided in the resonance portion. It is characterized by In the invention
described in the second aspect, the main air chamber and the sub air chamber are formed inside
the resonance portion, so that the size can be reduced as compared with the case where the sub
air chamber is disposed outside the case. The desired shape will be obtained. Furthermore, in the
invention described in claim 3, since the resonator is characterized in that it comprises a
resonator attached to the end of the case, and the resonator has a cylindrical portion which can
be inserted into the resonance portion. By attaching a resonator at the end of the main chamber,
the main air chamber and the sub air chamber are automatically formed, and the assembly
process can be further simplified.
[0009]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the
present invention will be described below with reference to the drawings. In the embodiment
described below, the members already described in FIG. 4 will be denoted by the same reference
numerals in the drawings to simplify or omit the description. FIG. 1 shows an embodiment
according to the present invention. In the microphone 10 in the present embodiment, as shown
in FIG. 1A, the resonator 11 is attached to an end (left end in the figure) of the case 41. The
resonator 11 is formed in a substantially deep dish shape for closing the end of the case 41 and
has an opening 12 through which sound waves can be introduced to the resonance unit 43 and a
wall 13 connected to the opening 12. doing.
[0010]
The opening 12 is circular and is provided at the center of the resonator 11. Therefore, the
opening 12 is arranged coaxially with the case 41 when the resonator 11 is attached to the end
of the case 41. On the other hand, the wall portion 13 is formed in a substantially cylindrical
shape, and is provided so that the inner circumferential surface is continuous with the opening
12. The wall 13 forms a gap 15 between the wall 13 and the microphone unit 42 when the four
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legs 14 provided on the end face abut on the front surface of the microphone unit 42. Such a
wall portion 13 partitions and forms a main air chamber 20 which is a first acoustic capacity on
the inner peripheral side, and partitions and forms an auxiliary air chamber 21 which is a second
acoustic capacity on an outer peripheral side. The sub air chamber 21 can be communicated only
with the main air chamber 20 through the gap 15 and is acoustically coupled to the main air
chamber 20.
[0011]
In such a microphone 10, the resonance frequency is mainly determined by the acoustic capacity
of the main air chamber 20, and the resonance sharpness is mainly determined by the acoustic
capacity of the sub air chamber 21. That is, in the microphone 10, the sub air chamber 21 and
the gap 15 for receiving the sound wave operate as an acoustic impedance, thereby controlling
the resonance of the main air chamber 20 by the parallel acoustic circuit (FIG. 1 (B )reference).
Therefore, the wall portion 13 is formed in the resonator 11 so that the resonance sharpness of
the high-frequency resonance characteristic of the microphone 10 becomes a desired value in
advance, in other words, the gap 15 has an appropriate shape and size.
[0012]
According to the microphone 10 of the present embodiment as described above, the main air
chamber 20 (first acoustic capacity) and the sub air chamber 21 (second acoustic room)
arranged in parallel along the direction intersecting the traveling direction of the sound wave.
Since the resonance is controlled by the parallel acoustic circuit based on the capacity, as shown
in FIG. 2, substantially uniform sensitivity is obtained over the entire area, and the high-pass
sensitivity does not decrease as in the conventional microphone. In addition, since the
microphone 10 does not use an acoustic resistance material for controlling resonance as in the
conventional microphone, the number of components can be reduced, and the assembly process
can be simplified. Furthermore, since the microphone 10 controls the resonance of the sound
wave by the parallel acoustic circuit, even when the microphone unit is unidirectional, the
directivity changes even if the acoustic impedance is increased as in the conventional series
resistance. Few. Therefore, this microphone 10 has less design restrictions as compared to a
conventional microphone, and a desired shape can be easily obtained.
[0013]
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Further, in the microphone 10 of the present embodiment, the main air chamber 20, which is the
first acoustic capacity, and the sub air chamber 21, which is the second acoustic capacity, are
formed inside the resonating portion 43. There are few. And since the main air chamber 20 and
the sub air chamber 21 are automatically formed by performing an extremely simple operation
of attaching the resonator 11 to the end of the case 41, the assembling process is further
simplified. Can be
[0014]
The microphones of the present invention are not limited to the microphones exemplified in the
above-described embodiment, and include, for example, the microphones 10A to 10D shown in
FIG. That is, the microphone 10A shown in FIG. 3A has a main air chamber 20A as a first acoustic
capacity and a second acoustic capacity as a first acoustic capacity by a resonator 44A obtained
by partially removing a resonator used in a conventional microphone. The air chamber 21A is
formed, and thereby, the same effect as the above-described embodiment can be obtained.
[0015]
Further, in the microphone 10B shown in FIG. 3B, the sub air chamber 21B is integrally formed
in advance at the end of the case 41B, and the resonance of the sound wave traveling through
the main air chamber 20B is obtained by the gap 15 and the sub air chamber 21. It is controlled
by. Further, in the microphone 10C shown in FIG. 3C, the auxiliary air chamber 21C protrudes in
the radial direction of the case 41C, and the resonance of the sound wave traveling through the
main air chamber 20C is controlled by the gap 15. Then, in the microphone 10D shown in FIG.
3D, the auxiliary air chamber 21D is formed along the axial direction of the outer peripheral
surface of the case 41C, and the resonance of the sound wave traveling in the main air chamber
20D is the gap 15 and the auxiliary air chamber It controls by 21 and. Also by these
microphones 10B to 10D, the same effect as that of the above-described embodiment can be
obtained.
[0016]
In addition, the material, shape, size, and form of the resonator, case, microphone unit, resonance
unit, main air chamber which is the first acoustic capacity, sub air chamber which is the second
acoustic capacity, wall portion, etc. The number, location, and the like are arbitrary and not
limited as long as the present invention can be achieved.
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[0017]
According to the invention described in claim 1 of the present invention, desired and good highpass sensitivity can be obtained, and since no acoustic resistance material is separately used, the
number of component parts can be reduced and the number of assembling steps can be reduced.
Simplification can be realized, and design restrictions can be reduced compared to the prior art.
Moreover, according to the invention described in claim 2, while the overall shape can be
miniaturized, a desired shape can be obtained. Furthermore, according to the invention described
in claim 3, the assembling process can be further simplified.
[0018]
Brief description of the drawings
[0019]
1 is a cross-sectional view and an acoustic equivalent circuit diagram showing an embodiment of
the present invention.
[0020]
2 is a graph showing the characteristics of the microphone.
[0021]
3 is a cross-sectional view and a schematic view showing a modification of the present invention.
[0022]
4 is a cross-sectional view and an acoustic equivalent circuit diagram showing a conventional
microphone.
[0023]
5 is a graph showing the characteristics of the conventional microphone.
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[0024]
Explanation of sign
[0025]
DESCRIPTION OF SYMBOLS 10 Microphone 11 Resonator 13 Wall part 41 Case 42 Microphone
unit 43 Resonant part 20 Main air room 21 which is 1st acoustic capacity Sub air room which is
2nd acoustic capacity
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