JPH0715279Y2 - Condenser microphone structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to the structure of a condenser microphone.

(Prior Art and Problems Thereof) The structure of a conventional condenser microphone is as shown in FIG. 1, where 1 is an electretized vibrating membrane, 2 is a metal ring attached to one surface of the vibrating membrane 1, and 3 is a thin film. Shaped space ring, 4 is a metal back plate with several holes 4a,
Reference numeral 5 is an inner case made of a cylindrical insulator, 6 is an impedance converter, 7 is a circuit board, 7a is a conductive pattern, and 8 is a metal case for fixing the above components. Thus, the capacitor 3-1 is formed by interposing the space ring 3 between the vibrating membrane 1 and the back electrode plate 4, and the inner case 5 is arranged on the surface of the back electrode plate 4 opposite to the capacitor 3-1. Then, the back air chamber 5-1 is formed by joining the circuit board 7 to the surface of the inner case 5 (the lower end surface in the drawing) that is not in contact with the back electrode plate 4.
The impedance converter 6 is built in the back air chamber 5-1.
The terminal 6-1 is connected to the back electrode plate 4, and the terminals 6-2, 6-3
Are connected to the circuit board 7. The electretized vibrating membrane 1 serving as one electrode of the capacitor 3-1 is
The back electrode plate 4 which is connected to the terminal 6-2 through the route of [metal ring 2 → metal case 8 → conductive pattern 7a] and serves as another electrode.
Is connected to the terminal 6-1. The capacitance change of the capacitor 3-1 caused by the vibration of the vibrating membrane 1 due to the sound pressure applied to the microphone, that is, the change of the electric charge is input to the terminal 6-1 of the impedance converter 6, and the output voltage is output to the terminals 6-2, 6 -3 is output. However, such a conventional condenser microphone has the following secondary points.

Since the space ring 3 is as thin as several tens of μm, it is difficult to handle, and there are cases where two sheets are inserted in an overlapping manner during production and assembly. In this case, the sensitivity becomes about half.

If the space ring is transparent, insertion failure may occur. In this case, the vibration of the vibrating film is obstructed, and the sensitivity having a desired frequency characteristic cannot be obtained.

Further, such a structure has a drawback that it has a large number of parts and is difficult to automate.

(Object of the Invention) In order to eliminate these drawbacks, the present invention reduces the number of parts by integrating a space ring, a back electrode plate, and an inner case with a structure of a condenser microphone. Is provided.

(Structure and operation of device) In order to achieve this object, the structure of the condenser microphone according to the present invention is such that a cylindrical body and an impedance converter are mounted, and the impedance converter is provided on one side of the cylindrical body. A circuit board located so that the output side terminal from the impedance converter penetrates from the inside to the outside, and a space ring portion located at the end of the body of the cylinder on the other end side of the cylinder. A back air chamber is formed by using a diaphragm disposed through the back air chamber, and a back electrode plate portion is formed in the back air chamber in the vicinity of the diaphragm to form a gap serving as a capacitor between the diaphragm and the back electrode plate. In the structure of the arranged condenser microphone, a diaphragm in which a conductor film is coated on an insulator thin plate to form an electret is used as the diaphragm, and the cylindrical body, the back electrode plate portion and the space are used. The ring part is a metal material And the circuit board, the integrated cylinder, and the vibration plate are sequentially stacked, and an assembly is formed through a metal ring in contact with the peripheral edge of the vibration plate. Is housed in a metal case whose one end is open, the open side end of the metal case is crimped to the peripheral edge of the circuit board, and the conductor film outside the diaphragm is the metal ring and the metal. It is connected to one of the output side terminals from the impedance converter via a case and a conductive pattern arranged on the surface of the circuit board, and the integrated cylinder body is connected via a conductive pattern arranged on the surface of the circuit board. And is connected to the input side terminal to the impedance converter.

The present invention will be described in detail below.

FIG. 2 (a) is a cross-sectional view of an electret condenser microphone according to the present invention, and 9 shows a conductor film 9a deposited on an insulator film 9b as shown in the enlarged view of FIG. 2 (b). Electretized vibrating membrane, 10 is a metal ring attached to the vibrating membrane, 11 is a back electrode that integrally forms a metal plate and a back electrode plate portion with several holes 11a and a spacer portion. Body (integrated cylinder), 12 impedance converter,
12-1, 12-2, 12-3 are its terminals, 13 is a circuit board, 13a, 13
Reference numeral b is a conductive pattern, and reference numeral 14 is a metal case for housing and fixing the above-mentioned components 13, 11, 9 and 10.

FIG. 3 is a sectional view of the back electrode body (integrated cylinder body) 11 used in the present invention. FIG. 4 is a plan view of the circuit board 13 used in the present invention, showing a conductive film pattern 13b arranged on the upper surface of the circuit board 13 and connected to the impedance converter 12.

As shown in FIG. 2, the circuit board 3 and the integral cylindrical body
The assembly in which 11 and the vibration plate 9 are sequentially stacked is housed in a metal case 14 having one end opened through a metal ring 10 in contact with the peripheral edge of the vibration plate 9, and the metal case 14 Has an open side end crimped to the peripheral edge of the circuit board 13, and the conductor film 9a outside the diaphragm 9 is disposed on the surface of the metal ring 10, the metal case 14, and the circuit board 13. Is connected to one of the output side terminals 12-2 from the impedance converter 12 via a conductive pattern 13a, and the integrated cylinder 11 is connected via a conductive pattern 13b arranged on the surface of the circuit board 13 It is connected to the input side terminal 12-1 to the impedance converter 12.

The conventional condenser microphone is for audio,
The frequency band is extended to near 20kHz, and the vibration diameter is designed to be small in order to increase the resonance frequency of the vibrating membrane. The gap 11-1 is also designed to have a considerably small value for the purpose of increasing the sensitivity as much as possible, and the dimension d between the vibrating membrane 9 and the back electrode plate portion of the back electrode body 11 is generally 38 μm.
It is a degree. The gap d has a great influence on the sensitivity of the microphone. When V is the charging voltage of the vibrating membrane 9 and d is the dimension between the vibrating membrane 9 and the back electrode plate portion of the back electrode body 11, it depends on the vibration of the vibrating film 9. If the change amount of d is Δd and the change amount of the voltage V at that time is ΔV, then ΔV = (V / d) · Δd,
ΔV is the output voltage of the microphone.

From the above, the dimension of d has a great influence on the output voltage value of the microphone, and it is required to have high accuracy including variations. Therefore, as shown in FIG. 1, the conventional dimensions of the gap are the vibrating membrane 1 and the back electrode plate 4.
The space ring 3 which is a thin ring is interposed between the two.

However, the condenser microphone of the present invention was developed for telephones, and in order to create frequency characteristics within the telephone frequency band of 0.3 to 3.4 kHz, the diameter of the vibrating membrane is made larger than the conventional product to lower the resonance frequency. , So that the gap is twice as large as that of the conventional microphone in terms of slack due to the temperature of the diaphragm and the realization of the target frequency characteristic.
By setting the thickness to 75 μm, the precision requirement of the dimension d, which has been required so far, is relaxed, and it becomes possible to form the shape of the space ring 3 on the outer peripheral portion of the back electrode plate 4. Thereby, the back electrode plate 4 and the space ring 3 could be integrated. Furthermore, by changing the conventional inner case 5 from an insulator to a metal body, as shown in FIG. 3, the space ring 3, the back electrode plate 4, and the inner case (cylindrical body) 5 are formed as an integral cylindrical body. We were able to.

FIG. 5 shows another embodiment of the present invention in which an insulating layer 15 is arranged between the back electrode body 11 and the metal case 14.

(Effect of the Invention) As described above, the condenser microphone according to the present invention reduces the number of parts by forming the conventional space ring, back electrode plate and inner case as an integrated cylinder.
Therefore, the structure is simplified, and the circuit board with the impedance converter, the integrated back electrode body (integrated cylinder), the diaphragm, and the metal ring are stacked in this order and housed in the metal case. Since the open end side of the metal case may be caulked to the peripheral portion of the circuit board, screwing is unnecessary, manufacturing is facilitated, and the assembly is suitable for automation. Furthermore, no adjustment is required after assembly, and good characteristics can be stably maintained.

[Brief description of drawings]

FIG. 1 is a sectional view of a conventional condenser microphone, and FIG.
Figures (a) and (b) are a sectional view and a partially enlarged view of a condenser microphone of the present invention in which a space ring, a back electrode plate and an inner case are integrated, and FIG. 3 is used in the embodiment of FIG. FIG. 4 is a sectional view of the back electrode body, FIG. 4 is a plan view of the circuit board used in the embodiment of FIG. 2, and FIG. 5 is another embodiment of the present invention in which an insulating layer 14 is provided between the back electrode body and the metal case. FIG. 1,9 …… Electretized diaphragm, 2,10 …… Metal ring, 3 …… Space ring, 3-1 …… Capacitor, 4 …… Back plate, 4a …… Hole, 5 …… Inner case (Cylindrical body), 5-1 ... back air chamber, 6,12 ... impedance converter, 6-1, 6-2, 6-3, 12-1, 12-2, 12-3 ... terminal, 7,
13 …… Circuit board, 8,14 …… Metal case, 9a …… Conductor film, 9b …… Insulator film, 11 …… Back electrode body (integrated cylinder), 11
a ... hole, 11-1 ... gap, 7a, 13a, 13b ... conductive pattern, 15 ... insulating layer.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-53-48519 (JP, A) JP-B 47-45536 (JP, B1) JP-B 50-8603 (JP, Y1)

Claims (1)

[Scope of utility model registration request] 1. A cylinder and an impedance converter are mounted, the impedance converter is located on one side of the cylinder, and the output side terminal from the impedance converter penetrates from the inside to the outside. A back air chamber is formed by using a circuit board arranged on the other side of the cylinder and a diaphragm arranged on the other end side of the cylinder via a space ring portion located at an end of the body of the cylinder. The back air chamber has a structure of a condenser microphone in which a back electrode plate portion that forms a gap between the diaphragm and the diaphragm is formed close to the diaphragm, and the diaphragm has an insulating thin plate. A diaphragm in which a conductor film is deposited on the diaphragm is used, and the tubular body, the back electrode plate portion, and the space ring portion are formed of a metal material as an integral tubular body, and the circuit is formed. Substrate, the integrated cylinder, the vibration The assembly in the state of being stacked in sequence is housed in a metal case having one end opened through a metal ring in contact with the peripheral edge of the diaphragm, and the open side end of the metal case is the peripheral edge of the circuit board. The conductor film on the outside of the diaphragm is connected to the output side terminal from the impedance converter via the metal ring, the metal case, and a conductive pattern arranged on the surface of the circuit board. A structure of a condenser microphone, which is connected to one side, and the integrated cylinder is connected to an input side terminal to the impedance converter via a conductive pattern arranged on the surface of the circuit board.