JP3919609B2 - Condenser microphone - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exchange capsule type condenser microphone, and more particularly to a condenser microphone provided with a pad for sensitivity adjustment (PAD).
[0002]
[Prior art]
In a condenser microphone, an attenuator (PAD) is used to prevent distortion of sound that occurs when excessive sound pressure is applied. The distortion of sound due to this excessive sound pressure is mainly generated by an electric circuit such as an impedance converter or an audio signal output circuit.
[0003]
This sound distortion can be prevented by reducing the input to the electric circuit of the microphone. Therefore, a capacitor is connected in parallel to the effective capacitance of the microphone unit in which the diaphragm and the back electrode are opposed to reduce the signal voltage applied to the input terminal of the electric circuit. This capacitor is a pad (PAD) capacitor.
[0004]
By the way, the microphone capsule is designed in advance to exhibit a specific directivity. Some models have one microphone capsule that can change the directivity. However, if you want to change the directivity of the microphone, the grip part (microphone body) is usually used as a common grip part. On the other hand, an exchange capsule type microphone in which a plurality of microphone capsules can be exchanged is used.
[0005]
Microphone directivity includes cardioid, omni, hyper cardioid, bi-directional and omni-directional, and different design directivities have different capacitance values. This is due to the difference in the control method for each directivity.
[0006]
For example, omni is elastic control and bilateral is resistance control. In addition, cardioid has both elastic control and resistance control properties, and hypercardioid has resistance control properties than cardioid.
[0007]
For this reason, if the directional frequency response is good and the sensitivity is the same even if the microphone capsule is replaced, the capacitances differ depending on the directivity. Since the appropriate attenuation rate by the pad capacitor is determined in relation to the capacitance of the microphone capsule, it is necessary to change the pad capacitor for each microphone capsule.
[0008]
Therefore, conventionally, when a microphone capsule is replaced, an attenuator called a pad ring having an attenuation rate suitable for the capsule is selected, and the microphone capsule is connected to the audio signal output circuit in the grip portion through the pad ring. Like to do.
[0009]
[Problems to be solved by the invention]
However, the pad ring is a microphone accessory part that must be purchased separately, and is a relatively small part that is easily lost. In addition, for example, when there is for -10 dB and for -20 dB, it is necessary to actually replace the pad ring in order to know which is optimal, and the operation is troublesome.
[0010]
Therefore, an object of the present invention is to make it possible to appropriately select the attenuation factor by the pad capacitor while the microphone capsule is attached to the grip portion without requiring a pad ring as a separate part. is there.
[0011]
[Means for Solving the Problems]
To solve the above problems, the present invention includes a microphone capsule which the signal detection electrode is drawn out of the microphone unit obtained by facing the diaphragm and backplate from unrealized said backplate into contact with the signal detection electrode And a grip part with a built-in electric circuit for audio signal output that has a connection terminal and processes and outputs a signal from the microphone unit, and the microphone capsule having a different directivity can be exchanged for the grip part. In the condenser microphone, a circuit board on which a ground side common line and a signal line included in the signal detection electrode are wired is provided in the microphone capsule, and the microphone capsule includes the microphone capsule. least one of the directivity have compatible capacitance, one end of which is connected to the ground side common line A capacitor pad, the operable knob from the outside of the microphone capsule and the other end of the capacitor the pad selectively connected to the signal line, a capacitor for the pad with respect to the effective capacitance of the microphone unit A changeover switch that is selectively connected in parallel is provided.
[0012]
According to this configuration, a predetermined attenuation factor can be selected simply by operating the changeover switch in a state where the microphone capsule is directly attached to the grip portion without using a pad ring or the like.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view of a condenser microphone according to the present invention in a state where a grip portion and a microphone capsule are separated, and FIG. 2 is a cross-sectional view of the microphone capsule taken along line AA in FIG.
[0014]
This condenser microphone is an exchange capsule type, and includes a grip portion 10 and a microphone capsule 20 that can be attached to and detached from the grip portion 10. Although not shown in the figure, the grip unit 10 is provided with an electric signal output power circuit, a power supply circuit, and the like for processing and outputting a signal from the microphone capsule 20.
[0015]
Note that the grip portion 10 is a so-called microphone body, and its outer shape and the like may be arbitrarily designed. The connecting means between the grip portion 10 and the microphone capsule 20 may be screw connection or bayonet connection, and is not particularly limited.
[0016]
The microphone capsule 20 houses a microphone unit 21 that is a combination of a diaphragm and a back electrode facing each other. In the present invention, the microphone unit 21 may have a known configuration.
[0017]
In the microphone capsule 20, the microphone unit 21 is supported by a support 22 made of a nonmagnetic material such as a synthetic resin, and a signal detection electrode 23 attached to the back electrode of the microphone unit 21 penetrates the support 22. It is pulled out downward.
[0018]
A circuit board 24 is disposed on the bottom side of the microphone capsule 20, and the lower end of the signal detection electrode 23 is exposed on the bottom side of the circuit board 24 so that it can be connected to a connection terminal (not shown) on the grip 10 side. ing. A plan view of the circuit board 24 on the component mounting surface side is schematically shown in FIG.
[0019]
Explaining only what is necessary for the present invention, for example, two capacitor pads C1 and C2 and one of the capacitor capacitors C1 and C2 are connected in parallel to the microphone unit 21 on the circuit board 24. Or a changeover switch 25 having a three-contact changeover mode that is not connected to the microphone unit 21.
[0020]
In this example, the changeover switch 25 is a slide type, and the knob 251 of the changeover switch 25 is disposed so as to be exposed at a part of the peripheral surface of the microphone capsule 20 in order to facilitate the changeover operation.
[0021]
As shown in the connection diagram of FIG. 4, it is assumed that the signal line 23a included in the signal detection electrode 23 and the ground-side common line 23b are led out from the microphone unit 21, and in this example, pad capacitors C1, C2 are used. One end of each is connected to the common line 23b side.
[0022]
The changeover switch 25 includes a common terminal 25a and three changeover terminals 25b to 25d that are alternatively connected to the common terminal 25a by a knob 251. The common terminal 25a is connected to the signal line 23a.
[0023]
The other end of one pad capacitor C1 is connected to the switching terminal 25b, and the other end of the other pad capacitor C2 is connected to the switching terminal 25d. The middle switching terminal 25c is a neutral terminal that is electrically floating.
[0024]
As an example, it is assumed that the effective capacitance Cb of the microphone unit 21 is 20 pF, the capacitance of one pad capacitor C1 is 200 pF, and the capacitance of the other pad capacitor C2 is 60 pF.
[0025]
When the knob 251 of the changeover switch 25 is slid from the neutral position in FIG. 1 to the right side, for example, and the changeover switch 25 is switched to the changeover terminal 25b side, one pad capacitor with respect to the effective capacitance Cb of the microphone unit 21. C1 is connected in parallel, and an attenuation factor of −20 dB is obtained.
[0026]
In contrast, when the knob 251 of the changeover switch 25 is slid from the neutral position in FIG. 1 to the left side, for example, and the changeover switch 25 is switched to the changeover terminal 25d side, the effective capacitance Cb of the microphone unit 21 is The other pad capacitor C2 is connected in parallel, and an attenuation factor of -10 dB is obtained.
[0027]
When the knob 251 of the changeover switch 25 is in the neutral position in FIG. 1, the changeover terminal 25c is selected, and neither the pad capacitors C1 nor C2 is connected to the effective capacitance Cb of the microphone unit 21. The attenuation rate is 0 dB.
[0028]
Thus, in the present invention, the replaceable microphone capsule 20 itself has a pad capacitor, and the attenuation factor can be selected by the changeover switch, so that a pad ring as a separate part can be provided. Sensitivity can be adjusted without using it.
[0029]
In the above embodiment, two pad capacitors C1 and C2 are mounted on the microphone capsule 20. However, the number of pad capacitors can be appropriately selected. Moreover, although the changeover switch 25 is a mechanical switch, it can be replaced with an electronic switch.
[0030]
【The invention's effect】
As described above, according to the present invention, the microphone capsule including the microphone unit in which the diaphragm and the back electrode are opposed to each other can be exchanged for the grip portion in which the electric circuit for outputting the audio signal is incorporated. In the microphone, the microphone capsule is provided with at least one pad capacitor and a changeover switch for selectively connecting the pad capacitor in parallel to the effective capacitance of the microphone unit. Without requiring a pad ring or the like, the attenuation rate by the pad capacitor can be appropriately selected while the microphone capsule is still attached to the grip portion, and the sensitivity can be easily adjusted when the microphone capsule is replaced.
[Brief description of the drawings]
FIG. 1 is a front view showing a state in which a grip portion and a microphone capsule of a condenser microphone according to the present invention are separated.
FIG. 2 is a cross-sectional view of the microphone capsule taken along line AA in FIG.
FIG. 3 is a schematic plan view of a circuit board provided in the microphone capsule.
FIG. 4 is a connection diagram for explaining a connection state of a pad capacitor with respect to a microphone unit of the microphone capsule.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Grip part 20 Microphone capsule 21 Microphone unit 22 Support body 23 Detection electrode 24 Circuit board 25 Changeover switch 251 Knob C1, C2 Pad capacitor

Claims (1)

A microphone capsule which the signal detection electrode is drawn out of the microphone unit obtained by facing the diaphragm and backplate from unrealized the back electrode, the signal from the microphone unit has a connection terminal for contacting the signal detection electrode A condenser microphone having a built-in electric circuit for outputting an audio signal for processing and outputting, and the microphone capsule having a different directivity with respect to the grip part can be replaced.
In the microphone capsule, a circuit board on which a ground side common line and a signal line included in the signal detection electrode are wired is provided, and the circuit board conforms to the directivity of the microphone capsule. At least one pad capacitor having capacitance and one end connected to the ground side common line, and the other end of the pad capacitor selected as the signal line by a knob operable from the outside of the microphone capsule And a switch for selectively connecting the pad capacitor in parallel to the effective capacitance of the microphone unit.

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