JP2001078297A - Condenser microphone device and its relay device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the noise output of a high-frequency signal over a wide carrier frequency range by connecting one end of a bypass capacitor to the signal output terminal of an amplifying means and the other end to the common output terminal of the amplifying means, and inserting series resistances between the signal output terminal of the amplifying means and a device output terminal, and the common output terminal of the amplifying means and a device common output terminal. SOLUTION: A capacitor microphone unit 10b has a series resistance 24 inserted between the drain of an FET 19 and a microphone signal output terminal 22. For example, the equivalent series resistance of the bypass capacitor 21 is <=1 Ω, so a resonance current between a microphone signal output power transmission line 31 and the bypass capacitor 21 is reducible to 1/10 to 1/100 by setting the series resistance to tens to hundreds of Ω and the high frequency voltage applied to the drain of the FET 19 is also reducible to 1/10 to 1/100. Consequently, noise generated with a high-frequency signal radiated or conducted from the transmission part of a radio device can be suppressed low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condenser microphone for converting acoustic vibration into an electric signal, and more particularly to a condenser microphone having a built-in impedance conversion element.

[0002]

2. Description of the Related Art Generally, a condenser microphone device includes a condenser microphone unit, a microphone signal output transmission line,
It is composed of a load resistance, a power supply and the like.

Conventionally, when a condenser microphone device is used in a portable telephone or the like, there is a problem that noise is output due to radiation of a high-frequency signal from a transmission unit. For this measure,
As a condenser microphone device, a method of providing a bypass capacitor between a source and a drain of an internal FET (electrostatic effect transistor) is known.

First, the configuration of a condenser microphone unit in a conventional condenser microphone device will be described with reference to the drawings.

FIG. 11A is a sectional structural view of a conventional condenser microphone unit in which a bypass capacitor is provided between a source and a drain of an FET. In FIG. 11A, a condenser microphone unit includes a face cloth 11 for preventing dust from entering the inside, a sound input hole 12, a metal case 13 also serving as a shield, and a movable electrode 1 vibrating by acoustic vibration.
4, movable electrode ring 15, spacer 16, fixed electrode 1
7, an insulator 18, an FET 19, a wiring board 20, a bypass capacitor 21, a microphone signal output terminal 22, and a microphone common output terminal (ground terminal) 23.

The movable electrode 14, the fixed electrode 17, and the spacer 1
Reference numeral 6 denotes a capacitor, and the movable electrode 14 and the fixed electrode 17 are made of an electret material itself or have an electret material adhered thereto, and charge is accumulated on the surface thereof. The spacer 16 insulates the movable electrode 14 from the fixed electrode 17. The movable electrode ring 15 supports the movable electrode 14, and the insulator 18 supports the fixed electrode 17 while insulating it. The FET 19 buffers and amplifies a voltage generated in a capacitor composed of the movable electrode 14 and the fixed electrode 17, and has an internal bias setting element (diode). The wiring board 20 also seals the back surface while performing circuit wiring. The bypass capacitor 21 is a capacitor that bypasses a high-frequency signal entering from the outside to a common output terminal.

FIG. 11B is a bottom view of the condenser microphone unit. Since the planar shape is a circle, the microphone signal output terminal 22 and the microphone signal common terminal 23 are arranged on a concentric circle so that contact is possible even if the orientation is not fixed. Others have a pin terminal.

Next, the operation of the conventional microphone condenser device will be described with reference to FIG. FIG.
FIG. 2 is a circuit diagram of a conventional condenser microphone device.

The microphone signal transmission line 31 is used for wiring on a mother board of a device such as a portable telephone. The decoupling capacitor 35 (including a parasitic capacitor between the microphone signal output transmission line 31 and the ground pattern) also reduces a high-frequency signal that is superimposed on the microphone signal output transmission line 31. Similarly, load resistance 32, power supply 3
Reference numeral 3 is installed on a mother board in a device such as a mobile phone. The microphone signal output transmission line 31 is considered to be grounded at a high frequency at the decoupling capacitor 35 due to the circuit configuration.

The high frequency signal is transmitted to the microphone signal output transmission line 31.
Is applied to the microphone signal output terminal 22 through the FET
Join 19 drains. This high-frequency signal is supplied to the FET1
9 is applied to the gate via the drain-gate capacitance, and the bias diode of FET 19 or FET 1
AM detection is performed by the pn junction of the channel 9 and the gate, and a direct current component is converted to audible noise. In the high carrier frequency band of the radio, the microphone signal output transmission line 31
Functions as an inductor, and the bypass capacitor 21 functions as a series body of a capacitance and a parasitic inductor, so that parallel resonance or series resonance occurs at a specific frequency.
For example, at the frequency of series resonance due to the capacitance of the bypass capacitor 21 and the parasitic inductor, the terminal voltage of the bypass capacitor 21 becomes small, so that the high-frequency voltage applied to the drain of the FET 19 is small, and noise at this frequency is not generated. Absent. On the other hand, a large resonance current flows at the series resonance frequency of the bypass capacitor 21 and the microphone signal output transmission line 31. This is the bypass capacitor 2
1 and the microphone signal output transmission line 31 have an extremely small equivalent series resistance. For this reason, the terminal voltage of the bypass capacitor 21 increases, and the high-frequency voltage applied to the drain of the FET 19 is large. Even a small high-frequency signal generates large noise in the condenser microphone device.
As described above, since the magnitude of the high-frequency voltage applied to the drain of the FET 19 changes greatly depending on the frequency of the high-frequency signal, it has been difficult to keep it low over a wide band.

[0011]

When the condenser microphone device having such a configuration is used in a portable telephone or the like, the antenna and the condenser microphone device are likely to be arranged at portions separated from each other due to the equipment configuration. This is because the receiver is near your ear,
In addition, it is necessary to arrange the condenser microphone device near the mouth, and to arrange the antenna at a position as high as possible because the radiation efficiency is high, so that the antenna is arranged near the receiver. Furthermore, due to the miniaturization of the equipment and the increase in the carrier frequency, the length of the antenna is shortened, and due to the radiation characteristics of the antenna, a high high-frequency voltage is induced on the opposite side of the antenna, and the high-frequency voltage applied to the condenser microphone device located there is increased. The voltage is getting higher. In addition, the wiring length is long, and the arrangement is such that a high-frequency voltage is easily superimposed. Therefore, it is becoming impossible to cope with only the bypass capacitor which is a conventional measure. Further, some mobile phones use two frequency bands, and it is necessary to take noise countermeasures at different frequencies.

An object of the present invention is to provide a condenser microphone device and a relay device for reducing a noise output generated by a high-frequency signal radiated or transmitted from a transmission unit of such a wireless device.

[0013]

A condenser microphone device according to the present invention comprises a movable electrode vibrating by acoustic vibration, a fixed electrode arranged opposite to the movable electrode, and a terminal voltage of the movable electrode and the fixed electrode. Amplifying means for buffering and amplifying, a bypass capacitor having one end connected to a signal output terminal of the amplifying means and the other end connected to a common output terminal of the amplifying means, a signal output terminal of the amplifying means and a device output terminal. And a series resistor inserted in at least one of the common output terminal of the amplifying means and the device common output terminal. With this configuration, it is possible to reduce a noise output due to a high-frequency signal radiated or transmitted from the transmission unit of the wireless device in a wide carrier frequency range, and to increase a breakdown resistance of DC static electricity applied to the microphone signal output terminal. It has the action of:

Further, the condenser microphone device of the present invention comprises:
A movable electrode vibrating by acoustic vibration, a fixed electrode disposed opposite to the movable electrode, amplifying means for buffer-amplifying terminal voltages of the movable electrode and the fixed electrode, and one end connected to a signal output terminal of the amplifying means. And a bypass capacitor whose other end is connected to a common output terminal of the amplifying means, and a blocking capacitor whose one end is connected to a signal output terminal of the amplifying means and the other end is connected to a common output terminal of the amplifying means. And a series body of a dump resistor. This configuration has an effect that a noise output due to a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced in a wide carrier frequency range.

Further, the relay device of the present invention, a movable electrode vibrating by acoustic vibration, a fixed electrode arranged opposite to the movable electrode, and buffer-amplifies a terminal voltage of the movable electrode and the fixed electrode. A relay device connected to a capacitor microphone unit including an amplifying unit and a bypass capacitor having one end connected to a signal output terminal of the amplifying unit and the other end connected to a common output terminal of the amplifying unit; A series resistor is provided between at least one of the signal output terminal and the device output terminal and between at least one of the common output terminal of the amplifying means and the device common output terminal. With this configuration, the noise output due to the high-frequency signal radiated or transmitted from the transmission unit of the wireless device,
Can be reduced over a wide carrier frequency range,
Further, it has the effect of increasing the breakdown strength of DC static electricity applied to the microphone signal output terminal.

Further, the relay device of the present invention comprises a movable electrode vibrating by acoustic vibration, a fixed electrode arranged opposite to the movable electrode, and an amplifier for buffer-amplifying terminal voltages of the movable electrode and the fixed electrode. A signal output terminal of the amplifying means, the signal output terminal of the amplifying means being connected to a condenser microphone unit having one end connected to a signal output terminal of the amplifying means and the other end connected to a common output terminal of the amplifying means. One end is connected to a terminal, and the other end is provided with a blocking capacitor and a series body of a dump resistor connected to a common output terminal of the amplifying means. This configuration has an effect that a noise output due to a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced in a wide carrier frequency range.

Further, the relay device of the present invention comprises a movable electrode vibrating by acoustic vibration, a fixed electrode arranged opposite to the movable electrode, and an amplifier for buffer-amplifying terminal voltages of the movable electrode and the fixed electrode. A bypass capacitor having one end connected to a signal output terminal of the amplifying means and the other end connected to a common output terminal of the amplifying means, and a signal output of the amplifying means. A series resistor inserted between at least one of the terminal and the device output terminal and at least one between the common output terminal of the amplifying means and the device common output terminal. With this configuration, noise output due to a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced in a wide carrier frequency range, and the breakdown resistance of DC static electricity applied to the microphone signal output terminal can be increased. It has the action of:

Further, the relay device of the present invention comprises a movable electrode vibrating by acoustic vibration, a fixed electrode arranged opposite to the movable electrode, and an amplifier for buffer-amplifying terminal voltages of the movable electrode and the fixed electrode. A bypass capacitor having one end connected to a signal output terminal of the amplifying means and the other end connected to a common output terminal of the amplifying means, and a signal output of the amplifying means. One end is connected to a terminal, and the other end is provided with a blocking capacitor and a series body of a dump resistor connected to a common output terminal of the amplifying means. This configuration has an effect that a noise output due to a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced in a wide carrier frequency range.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a circuit diagram of a condenser microphone device according to a first embodiment of the present invention. The circuit diagram of the conventional condenser microphone device shown in FIG. 24 is added.
In the condenser microphone unit 10b of FIG. 1, the series resistor 24 is inserted between the drain of the FET 19 and the microphone signal output terminal 22.

The series resistor 24 is provided for the purpose of limiting the resonance current, and is disposed in series with a series resonator composed of the microphone signal output transmission line 31 and the bypass capacitor 21 on a high frequency equivalent circuit. . Since the equivalent series resistance of the bypass capacitor 21 is 1 Ω or less, the resonance current between the microphone signal output transmission line 31 and the bypass capacitor 21 is reduced to 1 by setting the series resistance 24 to several tens Ω to several hundred Ω.
Therefore, the high-frequency voltage applied to the drain of the FET 19 can be reduced to 1/10 to 1/100. Therefore, noise generated by a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced. The series resistor 24 hardly affects the acoustic signal converted from the acoustic vibration into the electric signal. This means that an acoustic signal appearing from the drain of the FET 19 may be regarded as a current source due to the operational characteristics of the FET. The acoustic signal is a product of the signal current value and the load resistance value at the load resistor 32 (1-2 kΩ). It is converted to a signal voltage.
Even if there is a series resistor 24 set to several tens Ω to several hundred Ω, F
Since the signal current value output from the drain of the ET 19 hardly changes, the acoustic signal voltage appearing across the load resistor 32 hardly changes. The series resistor 24 also works as a high-frequency attenuation filter that attenuates the high-frequency voltage superimposed on the microphone signal output transmission line 31 in cooperation with the bypass capacitor 21. For example, when the bypass capacitor 21 is set to 33 pF and the series resistor 24 is set to 100Ω, the cutoff frequency is about 48 MHz,
Frequencies above this frequency are attenuated. On the other hand, since the carrier frequency of the mobile phone is 800 MHz or higher, the terminal voltage of the bypass capacitor 21 can be reduced to 1/10 or less. Since the band of this filter is much wider than the band due to the series resonance of the capacitance of the bypass capacitor 21 and the parasitic inductor, it is possible to reduce noise for high-frequency signals over a wider band.

In the condenser microphone device of FIG. 1 of the first embodiment, the series resistor 24 is disposed in the case of the condenser microphone unit 10b. The same effect can be obtained even if it is arranged in another place. One end of the series resistor 24 may be connected to the drain of the FET 19, which is the signal output terminal of the amplifying means, and the other end may be connected to the device signal output and arranged in series with the microphone signal output transmission line 31. , The series resistor 24 is connected to the condenser microphone unit 10b.
The same effect can be obtained even if the device is arranged very close to the substrate of the mobile phone to which the device is connected. Such modifications and effects are the same for the bypass capacitor 21.

(Second Embodiment) FIG. 2 is a circuit diagram of a condenser microphone device according to a second embodiment of the present invention. FIG. 2 is a circuit diagram of the conventional condenser microphone device shown in FIG. 25 and a blocking capacitor 26 are added. In the condenser microphone unit 10c of FIG. 2, the dump resistor 25 and the blocking capacitor 26 for blocking direct current are connected in series, and the series body is connected in parallel to the drain of the FET 19 and the source of the FET 19. Dump resistor 25 and blocking capacitor 2
Numeral 6 is provided for the purpose of dumping parallel resonance, and is arranged in parallel with a parallel resonator composed of a microphone signal output transmission line 31 and a bypass capacitor 21 on a high frequency equivalent circuit. The equivalent series resistance of the bypass capacitor 21 is 1
Ω or less, the impedance at the time of parallel resonance of the microphone signal output transmission line 31 and the bypass capacitor 21 becomes very large. For example, if the bypass capacitor 21 is 33
Assuming that the inductance of the pF and the microphone signal output transmission line 31 is 1.2 nH, the resonance frequency is about 800 MHz, and the impedance of the bypass capacitor 21 alone at that time is about 6Ω. However, since the parallel resonance impedance including the inductance of the microphone signal output transmission line 31 is about 40Ω to 80Ω, the bypass capacitor 21
The amount of attenuating the high frequency signal is smaller than that of the simple substance. However, by connecting a series body composed of the dump resistor 25 and the blocking capacitor 26 in parallel to the drain of the FET 19 and the source of the FET 19, the parallel resonance impedance can be reduced to the same value as the value of the dump resistor 25. Thus, the high-frequency voltage applied to the drain of the FET 19 can be reduced. The blocking capacitor 26
Is to prevent the DC bias voltage and the acoustic signal applied to the drain of the FET 19 from leaking to the microphone common output terminal 23 which is the source potential of the FET 19, and to prevent the high frequency signal current from flowing quickly to the dump resistor 25. Set to the capacitance value. The value of the dump resistor 25 is
It is set to several Ω to several tens Ω from the relation of the resonance impedance. With the configuration described above, noise generated by a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced. Above the cutoff frequency of the dump resistor 25 and the blocking capacitor 26, the parallel impedance of the bypass capacitor 21 and the inductance of the microphone signal output transmission line 31 is suppressed to a low value by the value of the dump resistor 25. This value is wider than the band due to the series resonance of the capacitance of the bypass capacitor 21 and the parasitic inductor, and it is possible to reduce noise for a high-frequency signal over a wider band.

In the condenser microphone device of FIG. 2 of the second embodiment, the dump resistor 25 and the blocking capacitor 26 are arranged in the case of the condenser microphone unit 10b, but they are electrically connected. If the condition is satisfied, the same effect can be obtained even if the device is arranged in another place. One end of the series body of the dump resistor 25 and the blocking capacitor 26 may be connected to the drain of the FET 19, which is the signal output terminal of the amplifier, and the other end may be connected to the source of the FET 19, which is the common output terminal of the amplifier. Therefore, for example, the same effect can be obtained even if the dump resistor 25 and the blocking capacitor 26 are arranged very close to the substrate of the portable telephone to which the condenser microphone unit 10b is connected. Such modifications and effects are the same for the bypass capacitor 21.

(Third Embodiment) FIG. 3 is a circuit diagram of a conventional condenser microphone unit and a relay device (connector) according to a third embodiment of the present invention. 3, the series resistor 27 is included in the relay device 40. Both ends of the series resistor 27 are connected to a connector signal input terminal 41 and a connector signal output terminal 43. The connector signal input terminal 41 and the connector common input terminal 42 are connected to the microphone signal output terminal 2 of the condenser microphone unit 10a.
2 and a microphone common output terminal 23 are connected to each other. The connector signal output terminal 43 and the connector common output terminal 44 are connected to the microphone signal output transmission line 31 and the common end (ground) on the motherboard of a device such as a mobile phone, respectively. Amplifier 3
4 together with a condenser microphone device for converting an acoustic signal from a cellular phone into an electric signal.

Since the series resistor 27 is arranged in series with the series resonator composed of the microphone signal output transmission line 31 and the bypass capacitor 21, the series resistor 27 is connected to the transmission unit of the wireless device in the same manner as in FIG. 1 of the first embodiment. Noise generated by radiated or transmitted high-frequency signals can be reduced. In the above embodiment, the series resistor 27 that contributes to the attenuation of the high-frequency signal is provided in the relay device.
The same effect as in the first embodiment can be obtained.

(Fourth Embodiment) FIG. 4 is a circuit diagram of a conventional condenser microphone unit and a relay device (connector) according to a fourth embodiment of the present invention. In FIG. 4, a dump resistor 28 and a blocking capacitor 29 are included in the relay device 40b. The dump resistor 28 and the blocking capacitor 29 are connected in series, and both ends are connected to a connector signal input terminal 41 and a connector common input terminal 42. The condenser microphone unit 10a is connected to the connector signal input terminal 41 and the connector common input terminal 42.
Microphone signal output terminal 22 and microphone common output terminal 2
3 are respectively connected. Since the dump resistor 28 and the blocking capacitor 29 are arranged in parallel with the parallel resonator composed of the microphone signal output transmission line 31 and the bypass capacitor 21, as in FIG. 2 of the second embodiment,
Noise generated by a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced. In the above embodiment, the dump resistor 28 and the blocking capacitor 29 that contribute to the attenuation of the high-frequency signal are connected to the relay device 4.
0b, the condenser microphone unit 10
By combining with a, the same effect as in the second embodiment can be obtained.

(Fifth Embodiment) FIG. 5 is a circuit diagram of a condenser microphone unit and a relay device (connector) according to a fifth embodiment of the present invention. In FIG. 5, a bypass capacitor 30 and a series resistor 27 are included in the relay device 40c. Both ends of the series resistor 27 are connected to a connector signal input terminal 41 and a connector signal output terminal 43. Also, both ends of the bypass capacitor 30
Connector signal input terminal 41 and connector common input terminal 42
It is connected to the. The microphone signal output terminal 22 and the microphone common output terminal 23 of the condenser microphone unit 10d obtained by removing the bypass capacitor 21 from the conventional condenser microphone unit of FIG. 12 are connected to the connector signal input terminal 41 and the connector common input terminal 42, respectively. I have.

Since the series resistor 27 is arranged in series with the series resonator composed of the microphone signal output transmission line 31 and the bypass capacitor 30, the series resistor 27 is connected to the transmitter of the wireless device in the same manner as in FIG. 1 of the first embodiment. Noise generated by radiated or transmitted high-frequency signals can be reduced. In the above embodiment, the bypass capacitor 30 and the series resistor 27 that contribute to the attenuation of the high-frequency signal are connected to the relay device 4.
0c, the same effect as in the first embodiment can be obtained by combining with the condenser microphone unit 10d having no countermeasures against high frequency noise.

(Sixth Embodiment) FIG. 6 is a circuit diagram of a condenser microphone unit and a relay device (connector) according to a sixth embodiment of the present invention. In FIG. 6, the bypass capacitor 30, the dump resistor 28, and the blocking capacitor 29 are included in the relay device 40d. Both ends of the bypass capacitor 30 are connected to a connector signal input terminal 41 and a connector common input terminal 42. Further, the dump resistor 28 and the blocking capacitor 29 are connected in series, and are connected in parallel with the bypass capacitor 30. The microphone signal output terminal 22 and the microphone common output terminal 23 of the condenser microphone unit 10d obtained by removing the bypass capacitor 21 from the conventional condenser microphone unit of FIG. 12 are connected to the connector signal input terminal 41 and the connector common input terminal 42, respectively. I have.

Dump resistor 28 and blocking capacitor 29
Are arranged in parallel with the parallel resonator composed of the microphone signal output transmission line 31 and the bypass capacitor 30,
As in the second embodiment, noise generated by a high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced. In the above embodiment, the bypass capacitor 30, the dump resistor 28, and the blocking capacitor 29 that contribute to the attenuation of the high-frequency signal are connected to the relay device 40.
d, the same effects as in the second embodiment can be obtained by combining with the condenser microphone unit 10d having no countermeasures against high frequency noise.

(Seventh Embodiment) FIG. 7 shows a relay device 4 according to a third embodiment and a fifth embodiment of the present invention.
0 and 46 are specifically shown. In FIG. 7, a rubber connector (relay device) 50 is composed of an insulating rubber 51, a resistive fiber 52 having medium conductivity, and a conductive fiber 53 having high conductivity. The signal terminal pattern 55 on the motherboard and the common terminal (ground end) pattern 56 on the motherboard are used to output the acoustic output from the condenser microphone units 10a and 10b to the motherboard 54 in a device such as a cellular phone.
It is configured to tell. In order to secure the connection between the conventional condenser microphone units 10a and 10b and the motherboard 54, a force is applied in a direction to compress the rubber connector 50 from above and below in the figure.

The resistive fiber 52 of the rubber connector (relay device) 50 is inserted between the microphone signal output terminal 22 and the signal terminal pattern 55 on the mother board, and has the same connection state as the series resistor 24 of FIG. Therefore, even when a high-frequency signal arrives from a microphone signal output transmission line (not shown) connected to the signal terminal pattern 55, noise derived from a high frequency can be suppressed.

In FIG. 7, the series resistor 27 is a resistive fiber 52, but this may be replaced with, for example, a conductive rubber whose volume resistance is adjusted.

The resistive fiber 52 may be replaced by, for example, a multilayer film having the dump resistor 28 and the blocking capacitor 29 formed on the upper or lower surface of the rubber connector 50. This multilayer film is composed of, for example, a conductive layer, a resistive layer, a dielectric layer, and a conductive layer, and has a series resistor 27 and a bypass capacitor 3 depending on the formation pattern and via holes.
0, a blocking capacitor 29 and a dump resistor 28 are formed.

Note that this film may be attached to the wiring board 20 of the first or second embodiment, and the same effect can be obtained in this case. By using a film in which such resistors and capacitors are integrated, the third, fourth, fifth, and sixth embodiments other than the above-described embodiment can be configured.

(Eighth Embodiment) FIG. 8 shows a relay device 4 according to a third embodiment and a fifth embodiment of the present invention.
0 and 46 are specifically shown. 8, a spring terminal connector (relay device) 60 includes an insulating case 61, a resistive spring contact 62 having a high resistivity, and a conductive spring contact 63 having a low resistivity. The signal terminal pattern 55 on the motherboard and the common terminal (ground end) 56 on the motherboard
The sound output from the condenser microphone units 10a and 10b is transmitted to a mother board 54 in a device such as a mobile phone.

The resistive spring contact 62 of the spring terminal connector (relay device) 60 is inserted between the microphone signal output terminal 22 and the signal terminal pattern 55 on the motherboard, and has the same connection state as the series resistor 24 of FIG. Become. Therefore, even when a high-frequency signal arrives from a microphone signal output transmission line (not shown) connected to the signal terminal pattern 55, noise derived from a high frequency can be suppressed.

In FIG. 8, the series resistor 27 is a resistive spring contact 62. For example, a thin material having a high resistivity is attached to the conductive spring contact to make contact with the microphone signal output terminal 22. The effect of the series resistor 27 may be provided on the surface.

(Ninth Embodiment) FIG. 9 shows an example in which a series resistor 24 according to a first embodiment of the present invention is formed by applying a resistor to the surface of the microphone signal output terminal 22 of the wiring board 20. It is a cross-sectional structural diagram of the condenser microphone unit showing
11A is different from the sectional structure diagram of the conventional condenser microphone unit shown in FIG. 11A in that a thick film series resistor 71 is added. The thick film series resistor 71 is formed on the microphone signal output terminal 22 by a method such as printing.

Since the thick-film series resistor 71 is arranged in series with the series resonator composed of the microphone signal output transmission line 31 and the bypass capacitor 21, the thick-film series resistor 71 is connected to the transmission unit of the wireless device in the same manner as in the first embodiment. Noise generated by radiated or transmitted high-frequency signals can be reduced. In the above embodiment, since the thick-film series resistor 71 contributing to the attenuation of the high-frequency signal can be formed on the microphone signal output terminal 22, it is only necessary to process the printed resistor on the wiring board 20 of the conventional condenser microphone unit. Thus, the same effect as in the first embodiment can be obtained.

In the condenser microphone device of FIG. 9 according to the ninth embodiment, the thick-film series resistor 71 is formed on the microphone signal output terminal 22 by printing or the like. The same effect can be obtained as long as the film has electric resistance deposited by any method.
For example, it may be formed by a thin film process such as vapor deposition.

The thick film series resistor 71 is formed on the microphone signal output terminal 22. This is the inner surface of the multilayer substrate even if the FET 19 is mounted on the front surface. The same effect can be obtained. In the former case,
In particular, if it is formed under the FET 19, the area of the substrate can be effectively used as in the latter case.
This has the advantage that other necessary components can be mounted.

(Tenth Embodiment) FIG. 10 shows a via hole (through hole) for electrically connecting the series resistor 24 of the first embodiment of the present invention to the component mounting surface of the wiring board 80 and the microphone signal output terminal 22. FIG. 12 is a cross-sectional structural view of a capacitor microphone device showing an example in which a resistor is filled in (hole) 82, and wiring board 20 in the cross-sectional structural diagram of the conventional capacitor microphone unit in FIG. The difference is that a series resistor 81 is added. The wiring board 80 also serves to seal the back surface while performing circuit wiring, and has a through hole extending from the drain of the FET 19 to the microphone signal output terminal 22 and a through hole extending from the source of the FET 19 to the microphone common output terminal 23. ing. The former is a series resistor 81 in a via filled or adhered to the side wall with a resistor whose conductivity is adjusted, and the latter is a via hole 8 filled with a highly conductive material or plated on the side wall.
It has two functions.

Since the series resistor 81 in the via is arranged in series with the series resonator composed of the microphone signal output transmission line 31 and the bypass capacitor 21, it radiates from the transmitter of the wireless device in the same manner as in the first embodiment. Alternatively, noise generated by the transmitted high-frequency signal can be reduced. In the tenth embodiment, since the in-via series resistance 81 contributing to the attenuation of the high-frequency signal can be formed in the wiring board 80, the wiring board 20 of the conventional condenser microphone unit can be formed.
The same effect as in the first embodiment can be obtained only by changing the construction method.

In the first, third, fifth, seventh, eighth, ninth and tenth embodiments, the series resistor is inserted between the microphone signal output terminal 22 or the microphone signal output transmission line 31 and the drain of the FET 19. Also, even when the electric charge accumulated in the human body or the like is discharged and jumps into a device such as a mobile phone, the current flowing into the microphone signal output terminal 22 can be suppressed to a low level. As a result, it is possible to obtain an effect of increasing the electrostatic breakdown resistance of the condenser microphone device.

The first embodiment can be used in combination with the second embodiment, the fourth embodiment or the sixth embodiment, and the second embodiment has Third
Embodiment 5 or Embodiment 5 can be used together, and Embodiment 3 can be used together with Embodiment 4 or Embodiment 6, and The fourth embodiment can be used together with the fifth embodiment, and the fifth embodiment can be used together with the sixth embodiment. In this case, since the series resistor 27, the dump resistor 28, and the blocking capacitor 29 are used at the same time, the effects obtained from each can be obtained. In the first to sixth embodiments, the series resistor, the dump resistor, and the blocking capacitor are arranged in the condenser microphone unit or the relay device. The same effect can be obtained even if it is arranged in another place. For example, the same effect can be obtained by disposing the condenser microphone unit or the relay device in a location very close to the substrate of the mobile phone to which the relay device is connected. Such modifications and effects are the same for the bypass capacitor.

In the first, third, fifth, and seventh to tenth embodiments, the series resistance is concentrated at one place, but this is further improved by distributing a plurality of resistances. The effect is obtained. For example, as in the first embodiment, the series resistor 24 and the third
As in the embodiment, the series resistor 27 is provided in the relay device 40a.
Further, by dispersing and arranging the series resistance in the middle of the microphone signal output transmission line 31, the transmission line is divided and shortened, so that the resonance frequency increases, and the FET 19
Is reduced. In this case, the transmission line 31 itself may be formed of a resistor, and the same effect can be obtained. These provide a further effect when the carrier frequency increases.

In the first to tenth embodiments, all or a part of the bypass capacitor, the series resistor, the blocking capacitor, and the dump resistor is a condenser microphone such as a portable telephone. It may be mounted very close to the motherboard of the equipment using the device, and in this case, the same effect can be obtained.

Further, these may be mounted on a child board (small piece board) provided between the condenser microphone device and the mother board, and the connection with the mother board of the device is made of a lead wire or a flexible wiring board. It is suitable for such a case, and also has the advantage that other anti-static components (such as varistors) and components against radio interference (such as high-capacity ceramic capacitors) can be mounted here. In this case, the shape of the microphone signal output terminal of the condenser microphone device is not limited to the contact type as in the first to tenth embodiments, but may be any type such as a pin terminal type that can be mounted on the daughter board.

When the series resistance in the first, third, fifth, seventh, and tenth embodiments is dispersed in order to obtain the above effect, not only the path of the microphone signal output terminal 22 but also the microphone common output terminal 23 It may be in the path to the ground of the motherboard. The condenser microphone unit is directly or
The first to first mounted on the mother board via the relay device
0, the impedance of the ground potential is considerably low.
It was good to pay attention to the drain of this, and consider bypassing this to the ground side. However, when the condenser microphone unit is placed away from the motherboard and mounted under the condition that the area of the ground pattern is small, the wiring impedance between the condenser microphone common output terminal 23 and the ground potential of the motherboard becomes the microphone signal output. The impedance is as large as the impedance of the transmission line, and the ground (case) potential of the condenser microphone unit also fluctuates at a high frequency. As a result, FET
A high frequency is applied to the drain-source voltage of No. 19 to generate noise. In such a case, by inserting the series resistor 24 separately in both paths of the microphone signal output terminal 22 and the microphone common output terminal 23, the high frequency voltage entering from these two paths can be reduced between the drain and source of the FET. can do. This is because the signal output from the condenser microphone unit is a current whose direction is opposite between the microphone signal output terminal 22 and the microphone common output terminal 23,
By making the high-frequency potentials of the two terminals equal, it can be said that a balanced operation state in which the high-frequency voltage applied to the microphone signal output terminal 22 and the microphone common output terminal 23 is reduced. As described above, the series resistor divided into both the microphone signal output terminal 22 and the microphone common output terminal 23 may be further divided, or the path itself may be formed by a resistor. If the value of the series resistance is selected so that the magnitude of the high-frequency voltage generated at the microphone common output terminal 23 becomes equal,
Greater effects can be obtained.

Although the FET 19 is used as the buffer amplifying means in the first to tenth embodiments, the same applies to other elements such as an operational amplifier having an FET input. The same effect can be obtained.

The elements such as the bypass capacitor, the series resistor, the dump resistor, and the blocking capacitor in the first to tenth embodiments are of a board-mounted type, but they are attached to the board surface by any method. The same effect can be obtained even with the film having the electric resistance and the structure having the capacitance. For example, it may be formed by a thin film process such as vapor deposition. Further, these may be formed on the surface on which the FET 19 is mounted, on the surface having the microphone signal output terminal 22, or on the inner layer of the multilayer substrate. Further, those formed on a film may be attached to the surface such as the surface on which the FET 19 is mounted or the surface having the microphone signal output terminal 22, or may be arranged on the inner layer of the multilayer substrate.

In the first to tenth embodiments, the weakened high-frequency voltage is applied to the drain side of the FET 19, but a relatively large high-frequency voltage is applied to the microphone signal output terminal 22. The high frequency voltage is applied to the high impedance fixed electrode 17 and the gate of the FET 19 through the space inside the condenser microphone unit. Noise due to this cause is caused by the fixed electrode 17 and F
This can be reduced by providing an electrostatic shield between the gate of the ET 19 and the microphone signal output terminal 22 and the series resistor 24, the dump resistor 25, and the bypass capacitor 21 connected thereto. For example, in the first embodiment, the problem can be solved by covering the electrode and the resistor of the series resistor 24 on the microphone signal output terminal 22 side with a shield layer connected to the microphone common output terminal 23 via an insulating layer. For example, when the series resistor 24 is formed by a printed resistor on the FET 19 side of the substrate, the electrode and the resistor of the series resistor 24 from the microphone signal output terminal are covered with an insulating film (for example, a resist film).
Furthermore, a shield layer can be formed by covering with a conductive layer connected to the microphone common output terminal. The conductive layer for shielding used here may be a thick-film resistor mixed with low resistance.

In the first and second embodiments, a condenser microphone unit having a structure in which the fixed electrode 17 is distinguished from the case 13 is used.
Other structures, for example, a structure in which the fixed electrode 17 and the case 13 are also used, can be similarly implemented, and the same effect is obtained.

In the method of converting acoustic vibration into an electric signal in the first to tenth embodiments, a method in which electric charges are accumulated on the surface of the movable electrode 14 or the fixed electrode 17 is used. , This is another method,
For example, a configuration in which a bias voltage is supplied from the outside or a configuration in which an applied AC bias is detected with a high impedance can be similarly implemented, and the same effect is obtained.

[0057]

As described above, according to the present invention, the advantageous effect that the noise output generated by the high-frequency signal radiated or transmitted from the transmission unit of the wireless device can be reduced with a small number of additional components is obtained.

Further, even in the conventional condenser microphone unit having no countermeasure for suppressing the high frequency noise, the noise output can be easily reduced by using the relay device having the element for suppressing the high frequency noise.

Further, an advantageous effect of increasing the breakdown strength due to static electricity can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a condenser microphone device including a condenser microphone unit according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a condenser microphone device including a condenser microphone unit according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a condenser microphone unit and a relay device according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a condenser microphone unit and a relay device according to a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram of a condenser microphone unit and a relay device according to a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram of a condenser microphone unit and a relay device according to a sixth embodiment of the present invention.

FIG. 7 is a sectional structural view of a condenser microphone unit and a relay device according to a seventh embodiment of the present invention.

FIG. 8 is a sectional structural view of a condenser microphone unit and a relay device according to an eighth embodiment of the present invention.

FIG. 9 is a sectional structural view of a condenser microphone unit according to a ninth embodiment of the present invention.

FIG. 10 is a sectional structural view of a condenser microphone unit according to a tenth embodiment of the present invention.

11A is a cross-sectional structural view showing a conventional condenser microphone device, and FIG. 11B is a diagram showing terminals of the conventional condenser microphone device.

FIG. 12 is a circuit diagram showing a conventional condenser microphone device.

[Explanation of symbols]

 Reference Signs List 14 movable electrode 17 fixed electrode 18 insulator 19 FET (buffer amplification means) 20, 80 wiring board 21 bypass capacitor 22 microphone signal output terminal 23 microphone common output terminal 24 series resistor 25 dump resistor 26 blocking capacitor 31 microphone signal output transmission line 40a , 40b, 40c, 40d Repeater (connector) 41 Connector signal input terminal 42 Connector common input terminal 43 Connector signal output terminal 44 Connector common output terminal 50 Rubber connector 51 Insulating rubber 52 Resistive fiber 53 Conductive fiber 54 Mother in device Board 55 Signal terminal pattern on mother board 56 Common terminal pattern on mother board 60 Spring terminal connector 61 Insulating case 62 Resistive spring contact 63 Conductive spring contact 71 Thick film series resistance 81 Series resistance in via 82 Via hole

Claims (22)

[Claims] A movable electrode oscillating by acoustic vibration; a fixed electrode disposed opposite to the movable electrode; an amplifying means for buffer-amplifying terminal voltages of the movable electrode and the fixed electrode; A bypass capacitor having one end connected to the signal output terminal and the other end connected to the common output terminal of the amplifying means, between the signal output terminal of the amplifying means and the device output terminal, and the common output terminal of the amplifying means; A capacitor microphone device comprising: a series resistor inserted into at least one of the device and a device common output terminal. 2. The condenser microphone device according to claim 1, wherein at least one of the series resistor and the bypass capacitor is formed of a multilayer film. 3. The condenser microphone device according to claim 1, wherein the series resistor is formed by attaching a resistor to a surface or an inner layer of a wiring board. 4. The condenser microphone device according to claim 1, wherein the series resistor is formed by filling a resistor in a via hole of a wiring board. 5. The condenser microphone device according to claim 1, wherein the series resistor is provided on a substrate provided outside the device. 6. The condenser microphone device according to claim 1, further comprising an electrostatic shield provided in at least one of the fixed electrode, the device signal output terminal, the bypass capacitor, and the series resistor. 7. A movable electrode vibrating by acoustic vibration, a fixed electrode arranged opposite to the movable electrode, an amplifying means for buffer-amplifying terminal voltages of the movable electrode and the fixed electrode, and an amplifying means for the amplifying means. A bypass capacitor having one end connected to the signal output terminal and the other end connected to the common output terminal of the amplifying means, and one end connected to the signal output terminal of the amplifying means and the other end connected to the common output terminal of the amplifying means. A capacitor microphone device comprising a connected blocking capacitor and a series body of a dump resistor. 8. The condenser microphone device according to claim 2, wherein at least one of the bypass capacitor, the dump resistor, and the blocking capacitor comprises a multilayer film. 9. The condenser microphone device according to claim 7, wherein the dump resistor is formed by attaching a resistor to a surface or an inner layer of a wiring board. 10. The condenser microphone device according to claim 7, wherein a series body of the blocking capacitor and the dump resistor is provided on a substrate provided outside the device. 11. The fixed electrode, a device signal output terminal,
The condenser microphone device according to claim 7, further comprising an electrostatic shield provided in at least one of the blocking capacitor and the dump resistor. 12. The condenser microphone device according to claim 1, wherein said amplifying means is constituted by a field effect transistor. 13. A movable movable electrode vibrating by acoustic vibration, a fixed electrode arranged opposite to the movable electrode,
A capacitor comprising buffer means for buffer-amplifying terminal voltages of the movable electrode and the fixed electrode; and a bypass capacitor having one end connected to a signal output terminal of the amplifier and the other end connected to a common output terminal of the amplifier. In a relay device connected to a microphone unit, a series resistor inserted between at least one of a signal output terminal and a device output terminal of the amplifying unit and at least one of a common output terminal and a device common output terminal of the amplifying unit. A condenser microphone device comprising: 14. A movable electrode vibrating by acoustic vibration;
A fixed electrode disposed opposite to the movable electrode; an amplifying means for buffer-amplifying a terminal voltage of the movable electrode and the fixed electrode; one end connected to a signal output terminal of the amplifying means and the other end being the amplifying means. In a relay device connected to a condenser microphone unit comprising a bypass capacitor connected to a common output terminal of the amplifying means, one end is connected to a signal output terminal of the amplifying means, and the other end is connected to a common output terminal of the amplifying means. A relay device including a blocking capacitor and a series body of a dump resistor. 15. A movable electrode vibrating by acoustic vibration;
In a relay device connected to a capacitor microphone unit including a fixed electrode arranged opposite to the movable electrode and an amplification unit for buffer-amplifying a terminal voltage of the movable electrode and the fixed electrode, a signal output terminal of the amplification unit And a bypass capacitor having one end connected to the other end and a common output terminal of the amplifying means, between a signal output terminal of the amplifying means and a device output terminal, and between a common output terminal of the amplifying means and a device common output. And a series resistor inserted between at least one of the terminals. 16. A movable electrode vibrating by acoustic vibration;
In a relay device connected to a capacitor microphone unit including a fixed electrode arranged opposite to the movable electrode and an amplification unit for buffer-amplifying a terminal voltage of the movable electrode and the fixed electrode, a signal output terminal of the amplification unit And a bypass capacitor having one end connected to the common output terminal of the amplifying means and one end connected to a signal output terminal of the amplifying means and the other end connected to a common output terminal of the amplifying means. A relay device including a blocking capacitor and a series body of a dump resistor. 17. The method according to claim 13, wherein the series resistor is made of a resistive fiber or a conductive rubber.
5. The relay device according to 5. 18. The method according to claim 1, wherein at least one of the series resistor and the bypass capacitor is formed of a multilayer film.
The relay device according to claim 3 or claim 15. 19. The relay device according to claim 14, wherein at least one of the bypass capacitor, the dump resistor, and the blocking capacitor is formed of a multilayer film. 20. The relay device according to claim 13, wherein the series resistor comprises a spring terminal connector formed of a resistive spring contact. 21. The relay device according to claim 13, wherein the series resistor is formed by attaching a resistor to a surface or an inner layer of a wiring board. 22. The relay device according to claim 14, wherein the dump resistor is formed by attaching a resistor to a surface or an inner layer of a wiring board.