JPS5986999

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DESCRIPTION JPS5986999
[0001]
The present invention relates to a condenser micro-bon, and more particularly to an installation
of an acoustic equalizer to improve directivity. FIG. 1 shows a conventional condenser
microphone. In the figure, a sound receiving port 4 for receiving sound is formed on the front
surface of a metal case 2 formed in a cylindrical shape, and the receiving port 4 is covered with a
dustproof cloth 6 attached to the front surface. A ring 10 with an electret diaphragm 8
(hereinafter simply referred to as a diaphragm) affixed to the inner surface of the metal case 2 is
disposed, and a spacer 12 is interposed in the back of the ring 10 to form the back electrode 14
and the acoustic resistance. The bodies 16 are arranged sequentially. That is, a gap 18 is formed
between the diaphragm 8 and the back electrode 14 by the interposition of the spacer 12.
Further, a plurality of through holes 20 are formed in the back electrode 14 at a position
separated by a predetermined distance from the center of the back electrode 14, and the acoustic
resistor 16 is made of a sound absorbing material such as cloth or paper. A support 24 is
provided between the back electrode 14 and the acoustic resistor 16 and the printed circuit
board 22 provided on the back of the metal case 2 in order to support the back electrode 14 and
the acoustic resistor 16. There is. The support 24 is formed by molding a synthetic resin or the
like, and has a cylindrical holding wall 26 for holding the back electrode 14 and the acoustic
resistor 16, and a plate for supporting the back portion of the acoustic resistor 16. The
supporting portion 28 and the leg portion 30 erected between the supporting portion 28 and the
printed circuit board 22. ! It is made. The supporting portion 28 has an IJ height 4 :! A similar
through hole 32 is formed at a position coincident with the through hole 20 of ji 14. A through
hole 34 is formed in the central portion of each support 1.1 portion 28 and the acoustic resistor
16, and the head of the 4J-shaped output terminal 36 is inserted into the through hole 34. The
output pole, one child 3G, and the back electrode 14 are electrically connected by welding. The
output terminal 36 is connected to a gate array 1 '42 of a field effect 1-transistor 40 as an
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impedance conversion element stored in a storage space 38 of the support 24. The drain lead 44
or source lead 4G of the electric field transistor 40 is drawn to the back of the purine 1 substrate
22 and is identical to the wiring 7.17 body 48 on the upper surface of the printed board 22 with
the solder 50 to Connected. Opening the metal case 2 on the back surface of the pudding 1group 4 22. . The parts h ′ ′ r ij are curled and fixed, and the respective components disposed
on the − side of the purine 1 substrate 22 are fixed to the inside 111 t of the metal case 2.
A lateral hole 52 is formed in the peripheral surface of the metal case 2 facing the space of the
leg 30 of the support 24 so that sound pressure acts on the back surface of the diaphragm 8
from the side wall of the metal case 2. It has become. In the condenser microphone configured in
this way, as shown in FIG. 2, when the sound pressure PI acts on the front surface, a part of the
sound pressure Pf is separated from the sound receiving port 4! Place i 51 [x−Yl] to act on the
diaphragm 8. Further, a part of the sound pressure P ′ ′ is transmitted from the lateral holes
52 of the side surface of the metal case 2 to the space portion of the leg portion 30 of the
support 24, the through hole 32 of the support portion 28, the acoustic resistor 16 and the back
electrode 14 It acts on the back of diaphragm 8 from gap 18 through hole 20. That is, in this
case, the path distance glt (X = Y 2) for the sound pressure Pf to act on is obtained. Here,
assuming that the sound pressure acting on the front surface of the diaphragm 8 is Pl and the
sound pressure acting on the rear surface thereof is P2, the sound pressure P is P1 # Pf. On the
other hand, the sound pressure P2 becomes P2 <Pf due to the difference ((X′′Y2) (X ′ ′ / s))
with the distances (X to Y2) and (X = Yt) and the attenuation by the acoustic resistor 16. For this
reason, sound pressure given by +3 I P 2 is applied to the diaphragm 8, and the diaphragm 8 is
driven by this sound pressure, which becomes the front sensitivity Fs of the condenser
microphone 1 cobon. Further, as shown in FIG. 3, when the sound pressure pb acts on the back
surface, the sound pressure pb reaches the diaphragm 8 at the same sound pressure pr as the
front sound pressure (n 1111). In this case, assuming that the sound pressure acting on the front
surface of the diaphragm is P1 and the sound pressure acting on the back surface is I) 2, the
sound pressures of p1 and P2 act on the front and back surfaces of the diaphragm 8 The
diaphragm 8 is driven by this sound pressure. However, in this case, since the starting point of
the pressure part is in the vicinity of the horizontal hole 52, the distance (X to Y2) becomes
shorter than the distance -11 (x to Y +), and the diaphragm is not provided. The sound pressure P
acting on the front surface of 8 is smaller than the sound pressure P2 on the rear surface, and
the back surface sensitivity Bs is given by this sound pressure difference ()) 2-l)). Immediately, if
there is no sound resistance resistor 16, it will be bi-directional "Ficlopong, so install the sound
resistance member 16 and make the sound pressure P1, P2 p1 = p2 so that the sound jj J +
resistance Adjust at 16 and have unidirectionality. In this type of condenser microphone, the
acoustic resistor 16 greatly affects the formation of unidirectionality, and its composition is
extremely important. Conventionally, since the acoustic resistor 16 is made of cloth or paper,
variations in thickness and air permeability affect the value of the resistance 1 resistance,
resulting in the disadvantage that the directivity becomes uneven.
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Further, in this condenser microphone, the sound I given by the acoustic resistor 16 is different
between the case where the through hole 32 of the support portion 28 and the through hole 20
of the back pole 14 coincide with each other and the case where they deviate from each other. ! !
４！ Since the resistance value changes and the directional characteristics vary, there is a
drawback that the structural yield is deteriorated because the uniform directional characteristics
are iη. An object of the present invention is to provide a condenser microphone in which an
acoustic equalizer is installed with a fixed gap in the front part of a diaphragm, the sound
pressure from the front and the sound pressure from the back are adjusted, and the directivity
characteristic is improved. . Embodiments of the present invention will be described in detail with
reference to the drawings. FIG. 4 shows an embodiment of the condenser microphone of the
present invention. In this example, the same part of the 21st indica microbon shown in vts 1
figure is the same sign. In the figure, the ring 54 and the equalizer plate 56 constituting the
inside of the metal case 2) 1) (sound on the front surface) II + equalizer are sequentially installed,
and the equalizer plate 5G has a constant pressure 811 or 1'1) If from its center A through hole
58 of one month or two months is formed at the fffl position. In the equalizer plate 56 of each
embodiment, a plurality of through holes 58 are formed with F / A for a certain period. A ring 10
to which a diaphragm 8 is attached is disposed on the back of the E1.sub.l1 j5G, and a back
electrode 14 is disposed on the back of the diaphragm 8 with a spacer 12 interposed. In the case
of this real hffi example, the transmission r L of the equalizer plate 56 and the transmission hole
2 o of the first eye 4 are set to be approximately f1: 6. In addition, the back surface portion of the
back electrode 14 is provided with a Lawa electrically conductive bellows (a back plate 62 is
provided with an io interposed therebetween; vl: conductive spacer 60 is provided between the
back electrode 14 and the JIJ ′ face plate 62. To form a gap 64. Further, a through hole 66 is
formed at the central portion of the back plate 62. A support 24 for supporting the back
electrode 14, the conductive spacer 60 and the back plate 62 is installed on the back surface of
the diaphragm 8, and the back electrode 14, the conductive spacer 60 and the back plate 62 are
held on the support 24. A holding wall 26, a support portion 68 for supporting the back plate 62
from the back surface, and a leg portion 30 are formed, and a beam 70 is provided at a position
displaced from the central portion. Between the beam 70 and the back plate 62, the gated gate
42 formed of the field effect 1-land disc 40 is inserted, and the gate lead 42 is firmly held
between the beam 70 and the back plate 62. The mechanical connection: the lead 1 lead 42 is
electrically connected to the back plate 62.
5 to 8 show components of the condenser microphone of this embodiment, FIG. 5 shows a ring
54 interposed on the front surface of the metal case 2, FIG. 6 shows an equalizer plate 56, and
FIG. The pole 14, FIG. 8 shows the conductive spacer 60 and the back plate 62. The conductive
spacer 60 in this embodiment is integrally fixed to the upper surface of the back plate 62 by six
methods such as printing, vapor deposition, or span-cling. j;) -in the configuration of FIGS. 9
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and 1015? This will be described with reference to I. FIG. 9 shows the result of removing the ring
54 constituting the acoustic equalizer and the equalizer plate 5G from the microphone of FIG. i is
shown. If there is a corresponding distance 81 F between the through hole 20 of the back
electrode 14 and the through hole 66 of the 1 v surface slope 62 as in this embodiment, if the
sound pressure pb acts on the back surface, f; 1; is the gold given by the distance (, X′′Y,) 2.)
from the side of the case 2 through the receiver 4 to the diaphragm 8; In addition, part of sound
pressure 1) b is distance! The gap between the legs 30 of the first housing 24 from the side hole
52 of the metal case 2 and the through hole 66 of the back plate 62 of the rear plate 62, as
shown in FIG. 60 formed by 60, +1. 'The diaphragm 8 is reached through the through holes 20 of
the pole 14 and the gap 18'. Thus, assuming that 7) pressure acting on the front surface of the
diaphragm 8 is P1 and sound pressure acting on the back surface thereof is P2, these sound
pressures 1) t and P2 have a distance (X to Y1) of 1 '1ll (X-Y 2) Y' '5i <Naruto (!: 、; 1 蛸 1 蛸 1 t
(X-Y 2) adds acoustic resistance due to the gap 18, so P1> P2, and this sound The vibrations 4fj,
8 are driven by the pressure difference. As a result, the back surface sensitivity BS is generated,
and the back surface sensitivity Bs has a small difference from the front surface sensitivity Fs,
and the Fs / Bs ratio as a single directivity becomes worse. Therefore, as shown in FIG. 10, the
case where the ring 54 and the equalizer plate 5G that constitute the equalizer are installed on
the inner surface of the metal case 2 will be described. As described above, when the equalizer
plate 56 is installed on the front surface of the diaphragm 8, when the sound pressure pb acts on
the rear surface, a part thereof is received from the side surface of the metal case 2 like the
distance Mll (x to y +). The diaphragm 8 is reached through the aperture 4, the gap 72 formed by
the ring 54, the through hole 58 of the equalizer plate 56 and the spacer 12 while passing
through 113 q 1 8. Also, its -j'l (like the distance Fill (X-Y 2)!
It reaches the diaphragm 8 through the same path as in FIG. In this case, assuming that the
sound pressure acting on the front surface of the diaphragm 8 is Pl and the sound pressure
acting on the rear surface thereof is P2, the distance (X ′ ′ ′ ′ Y +) is longer than the
distance Fill (X = Y 2), P2> P1. However, in consideration of the acoustic resistance due to the
gap 64, the sound pressure P1, ■) 2 becomes P1 # P2, and the sound pressure is almost equal,
so the drive of the diaphragm 8 does not occur. As a result, the difference between the back
surface sensitivity B S and the front surface sensitivity Fs becomes large, and the F s / B s ratio as
jlj-1 old iiJ property becomes large. Also, with this condenser microphone, the conventional old
town 11 roar j1. Instead of the antibody, a conductive spacer 60 is interposed between the back
electrode 14 and the back plate 62 to form a gap 64, and the radial air flow present inside the
gap 64! The acoustic resistance is constituted by + ', i-type resistance, and it is violated in irG's
acoustic resistance which is extremely accurate as compared with the acoustic resistor made of
1's, conventional cloth, paper or the like. In addition, the value of the acoustic resistance forms a
transparent TLGG at the center of the back plate 62, and the distance between the through hole
66 and the back electrode 14 G, j (p is relatively constant) till Therefore, uniform acoustic
resistance can be formed without the need for adjustment. Therefore, according to such a Conde
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Soli-Mike 1 copon, the 473 degree quotient sound 1; r,:! ill: The configuration of the anti (R
composition and the acoustic equalizer provided in front of it, the phase adjustment force of the
front sound and the back sound) Unidirectional characteristics can be obtained. Although the
embodiment has been described by taking the electret-notconden 1 J-microphone as an example,
the present invention is also applicable to condenser microphones other than electret condenser
microphones or condenser / Y sensor microphones having other structures, and similar effects
are expected. It is possible. As described above, according to the present invention, since the
acoustic equalizer is installed on the front surface of the diaphragm, the adjustment of the sound
pressure from the front and back surfaces becomes fil, and (f hl -f fil-forms the directional
characteristics be able to.
[0002]
Brief description of the drawings
[0003]
FIG. 1 shows a conventional condenser micronton, and FIG. 2 is a cross-sectional view of FIG. 2
and FIG. 3 is an explanatory view for eliminating .delta. Its directivity characteristic, and FIG. 5 is
a perspective view showing a ring, FIG. 6 is a perspective view showing an equal IJ = plate, and
FIG. 7 is a perspective view showing a back electrode, eighth dot, 1λ- FIG. 91 is a perspective
view showing an electric spacer and a back plate, and 91 g + and FIG. 10 are explanatory views
for explaining one old iiJ characteristic of the capacitor micro-bon of the present invention.
(... Electrish 1-diaphragm, 54 ... ring, 5 G ... 1: 1 riser plate. 7t Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8
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