JP5313058B2 - Unidirectional cylindrical condenser microphone - Google Patents

Description

The present invention relates to a unidirectional cylindrical condenser microphone having a structure capable of preventing occurrence of cavity resonance.

Normally, as shown in Patent Document 1 below, the condenser microphone unit is closed with one surface having a front acoustic terminal as a sound introduction hole and partitioning the other opened surface. A unit case in which an internal thread is engraved on the inner peripheral surface of the part, and in order from the front acoustic terminal side in the unit case toward the open end, a diaphragm ring having a diaphragm, a spacer ring, A fixed pole and an insulating seat for the diaphragm are accommodated, and the fixed pole is connected to the diaphragm ring side via the insulating seat by a lock ring that is screwed to the back surface of the insulating seat via a male screw that is screwed to the female screw. It is formed so that it can be pressed and fixed with a predetermined pressure.

JP 2004-343368 A

FIG. 2 is a diagram illustrating a general example of a unidirectional cylindrical condenser microphone formed by accommodating a conventional condenser microphone unit including the condenser microphone unit disclosed in Patent Document 1 in a cylinder. Of these, (a) shows a right side view and (b) shows a front view.

According to the figure, a unidirectional cylindrical condenser microphone 51 has a cylindrical body 52 having a rear acoustic terminal 54 on a peripheral surface 52a of a front end 53 thereof, and a front acoustic terminal 58 on a front end surface 57a. The condenser microphone unit 57 is screwed to the front end side of the cylindrical body 52.

Further, as is apparent from FIGS. 3 and 4, a circuit board 63 electrically connected to the output connector portion 62 accommodated in the rear end portion 56 is provided in the cylindrical body 52. The tip end side is disposed under the state of being held by the holding member 64.

That is, a space for accommodating and arranging the electronic circuit member including the circuit board 63 is required in the cylindrical body 52. As a result, the rear acoustic terminal 54 is located at a position where the rear acoustic terminal 54 is located after the arrangement. A cavity 55 communicating with the outside air via the rear acoustic terminal 54 is left.

And while the cavity 55 operates as an acoustic capacity, there is an acoustic mass at the rear acoustic terminal 54, so there is a problem that resonance occurs and the directional frequency response is degraded.

For this reason, the filling member 72 supported by the holding member 64 is disposed in the cavity 55 of the cylindrical body 52 so that the volume is reduced so that the resonance frequency can be raised to a high frequency. Has been.

Moreover, in the cavity 55, when flat surfaces face each other, a reflected wave is generated, and the directional frequency response is also deteriorated by the reflected wave, so that the filling member 72 faces the rear end side of the condenser microphone unit 107. The surface is not formed as a flat surface 73 as shown in FIG. 5A, but is formed into a hemispherical shape as shown in FIG. 5B or a frustoconical shape as shown in FIG. The protruding surface 78 is accommodated in the cavity 55.

By the way, it is necessary to arrange the interposing conductor part 75 for electrically connecting the extraction electrode rod 59 provided in the condenser microphone unit 57 and the circuit board 63 side in the filling member 72.

For this reason, since the filling member 72 itself needs to be electrically insulated from the intervening conductor portion 75, it has been formed using a synthetic resin such as polycarbonate having a high insulation property.

However, the filling member 72 satisfies the conditions such as that the sound wave entered from the rear acoustic terminal 54 can be guided to the condenser microphone unit 57 side, the volume of the cavity 55 can be reduced, and the sound wave is not reflected. Therefore, in order to satisfy these various conditions, the filling member 72 must be designed while repeating trial and error.

The present invention can effectively prevent the occurrence of cavity resonance by using a filling member that can function as an acoustic resistance, in view of the above-described problem of the prior art derived from a filling member that does not transmit sound waves . and, and to provide a unidirectional condenser microphone unit to be able to be easily satisfies the above conditions.

The present invention has been made in order to achieve the above object, and is a cylindrical body having a built-in electronic circuit member side held by a holding member at a rear position of a rear acoustic terminal provided on a peripheral surface of a front end portion. And a condenser microphone unit having a front acoustic terminal on the front end surface and detachably attached to the front end side of the cylindrical body, and a cavity secured in the front end portion of the cylindrical body via the holding member is In the unidirectional cylindrical condenser microphone unit in which the internal capacity is reduced by a filling member arranged to be supported by the holding member, the filling member includes an acoustic capacity of the cavity and an acoustic mass of the rear acoustic terminal. in order to prevent the occurrence of acoustic resistance is that equivalent connected cavities in parallel to the acoustic capacitance of the resonant circuit by a, a large number of continuous pores that acts as acoustic resistance hole to allow the transmission of acoustic waves It is the most important feature rapping formed by plastic sintered porous body.

In this case, it is preferable that the filling member is formed as a projecting surface that faces the condenser microphone unit in order to increase the cross-sectional area from the condenser microphone unit side toward the holding member side .

According to the first aspect of the present invention, since the plastic sintered porous body having a large number of continuous pores is used as the filling member, the continuous pores are operated as acoustic resistance holes, and the acoustic capacity of the cavity and the rear acoustic terminal Equivalent to the fact that the acoustic resistance is connected in parallel to the acoustic capacitance of the resonance circuit due to the acoustic mass, it is possible to effectively prevent the occurrence of cavity resonance.

According to the invention of claim 2, by a collision surface facing surfaces of the condenser microphone unit in the filling member, it is possible to increase the cross-sectional area toward the condenser microphone unit side to the electronic circuit member side Runode Therefore, it is possible to suppress the generation of the reflected wave and prevent the directional frequency response from deteriorating.

It is an expanded end view which shows the principal part structure in the longitudinal cross-section direction of this invention, (a) of them shows a 1st example, (b) shows a 2nd example, respectively. It is explanatory drawing which shows the general example of the unidirectional cylindrical capacitor | condenser microphone containing this invention, (a) of them shows a right side view, (b) shows a front view, respectively. FIG. 3 is an end view showing an example of a vertical cross-sectional structure of the unidirectional cylindrical condenser microphone shown in FIG. 2. FIG. 4 is an end view showing the unidirectional cylindrical condenser microphone shown in FIG. 3 in a state where a cylindrical body and a condenser microphone unit are separated. It is an expanded end view which shows the principal part structure in the longitudinal cross-section direction of the conventional unidirectional cylindrical condenser microphone, Of which (a) is a 1st prior art example, (b) is a 2nd prior art example, (C) shows a third conventional example.

Since the unidirectional cylindrical condenser microphone according to the present invention is formed to have substantially the same structure as that of the example shown in FIG. 2, the same portions are denoted by the same reference numerals and will be described below.

That is, as shown in FIG. 2, the unidirectional cylindrical condenser microphone 11 includes a cylindrical body 52 having a rear acoustic terminal 54 on the peripheral surface 52a of the front end portion 53 and a front acoustic wave on the front end surface 57a. The condenser microphone unit 57 has a terminal 58 and is detachably screwed to the distal end side of the cylindrical body 52.

Further, as is apparent from FIGS. 3 and 4, a circuit board 63 electrically connected to the output connector portion 62 accommodated in the rear end portion 56 is provided in the front end of the cylindrical body 52. The part side is arranged under the state of being held by the holding member 64.

For this reason, the space for accommodating and arranging the circuit board 63 and the like in the cylindrical body 52 includes a portion on the rear end portion 56 side where an electronic circuit member such as the circuit board 63 is accommodated and arranged via the holding member 64, and a capacitor The microphone unit 57 is partitioned into a portion facing the front end 53.

As a result, a cavity 55 communicating with the outside air via the rear acoustic terminal 54 is left in the portion of the cylindrical body 52 where the rear acoustic terminal 54 is located, and the cavity 55 operates as an acoustic capacity. .

Further, the cavity 5 5 to be secured in the front end portion 53 of the cylindrical body 52, so that it can be pulled frequency higher the resonance frequency, the filling member 12 is supported by the holding member 64 is arranged, the Due to the presence of the filling member 12, the capacity of the cavity 52 is reduced.

In this case, the filling member 12 is protruded toward the front end portion 53 of the cylindrical body 52 with an outer diameter smaller than the outer diameter of the circular flange portion 14 and the outer diameter of the circular flange portion 14 as shown in the illustrated example, for example. A cylindrical portion that is concentric with the main body portion 15 and can be fitted to a step portion 65 provided on the inner diameter side of the holding member 64 by projecting toward the back surface of the circular flange portion 14 with a smaller diameter. 16.

The filling member 12, the small-diameter through holes 17 than the inner diameter of the cylindrical portion 16 to the axis Direction is formed, interposed conductor portion 18 via the through hole 17 are inserted and arranged, the By using the intervening conductor portion 18 as a relay material, the extraction electrode rod 59 provided in the condenser microphone unit 57 and the circuit board 63 side as shown in FIG. 3 are electrically connected to each other.

In addition, since the filling member 12 is formed by using the plastic sintered porous body 13 having a large number of continuous pores (not shown), the continuous pores are operated as acoustic resistance holes and the acoustic capacity of the cavity 55 is increased. And an acoustic resistance connected in parallel with the acoustic capacitance of the resonance circuit due to the acoustic mass of the rear acoustic terminal 54.

The filling member 12 has a hemispherical shape as shown in FIG. 1A or a frustoconical shape as shown in FIG. 1B on the surface of the main body 15 facing the rear end side of the condenser microphone unit 57. By forming the projecting surface 15a as described above, the cross-sectional area is increased from the condenser microphone unit 57 side toward the holding member 64 side, and the projecting surface 15a is accommodated in the cavity 55.

Next, the operation and effect of the present invention having the above-described configuration will be described. The tube body 52 is accommodated in the rear end portion 56 as is apparent from FIGS. 3 and 4. The circuit board 63 electrically connected to the output connector portion 62 can be disposed in a state where the tip end side is held by the holding member 64.

In addition, the portion where the rear acoustic terminal 54 in the cylindrical body 52 after the electronic circuit member including the circuit board 63 is accommodated is located, is partitioned by the holding member 64 and communicates with the outside air via the rear acoustic terminal 54. The cavity 55 is left behind.

Moreover, since the filling member 12 supported by the holding member 64 is accommodated in the cavity 55 to reduce its volume, the resonance frequency can be raised to a high frequency, and the cavity 55 operates as an acoustic capacity. As a result, even if there is an acoustic mass in the rear acoustic terminal 54, an excellent directional frequency response can be exhibited without causing resonance.

Further, since the filling member 12 itself is formed by the plastic sintered porous body 13 having a large number of continuous pores, the continuous pores are operated as acoustic resistance holes, and the acoustic capacity of the cavity 55 and the rear acoustic terminal 54 are Equivalent to the fact that the acoustic resistance is connected in parallel to the acoustic capacitance of the resonance circuit due to the acoustic mass, it is possible to effectively prevent the occurrence of cavity resonance.

Further, the surface of the main body portion 15 of the filling member 12 facing the condenser microphone unit 57 is formed as a projecting surface 15a so that the cross-sectional area increases from the condenser microphone unit 57 side toward the holding member 64 side. In the case where it is, the generation of the reflected wave can be suppressed and the directivity frequency response can be prevented from deteriorating.

The above is the description of the present invention based on the illustrated example, and the specific configuration is not limited thereto. For example, the filling member 12 may be formed as a concave surface or a flat surface as shown in FIG. 5A, if desired, without forming the projecting surface 15a on the surface facing the condenser microphone unit 57. Further, the projecting surface 15a of the filling member 12 can be formed by providing an appropriate projecting shape other than the illustrated example.

DESCRIPTION OF SYMBOLS 11 Unidirectional cylindrical capacitor | condenser microphone unit 12 Filling member 13 Plastic sintered porous body 14 Circular collar part 15 Main body part 15a Projecting surface 16 Cylindrical part 17 Through-hole 18 Intervening conductor part 52 Cylindrical body 52a Circumferential surface 53 Front end part 54 Rear acoustic terminal 55 Cavity 56 Rear end portion 57 Capacitor microphone unit 57a Front end surface 58 Front acoustic terminal 59 Extraction electrode rod 62 Output connector portion 63 Circuit board 64 Holding member 65 Step portion

Claims (2)

A cylinder having a built-in electronic circuit member held by a holding member at a rear position of a rear acoustic terminal provided on the peripheral surface of the front end, and the cylinder having a front acoustic terminal on the front end A condenser microphone unit that is detachably attached to the front end side of the tube, and a cavity secured in the front end portion of the cylindrical body via the holding member is contained inside by a filling member arranged to be supported by the holding member In the unidirectional cylindrical condenser microphone unit with reduced capacity,
The filling member is equivalent to an acoustic resistor connected in parallel with the acoustic capacitance of the resonant circuit formed by the acoustic capacitance of the cavity and the acoustic mass of the rear acoustic terminal, so as to prevent the occurrence of cavity resonance. numerous unidirectional cylindrical condenser microphone unit, characterized in that formed by plastic sintered porous body having continuous pores that acts as acoustic resistance hole to allow transmission. 2. The unidirectionality according to claim 1, wherein the filling member is formed with a surface facing the condenser microphone unit as a projecting surface so as to increase a cross-sectional area from the condenser microphone unit side toward the holding member side . Cylindrical condenser microphone unit.

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