JPS58215900A - Electrostatic type electroacoustic transducer - Google Patents

Abstract

PURPOSE:To improve product precision easily by sticking a couple of frame bodies to both plate surfaces of a diaphragm and using those frame bodies as spacers for specifying the gap size between a solid electrode and the diaphragm. CONSTITUTION:A couple of fixed electrodes 22a and 22b are arranged in a housing 21 at its upper part. Consequently, the diaphragm 24 having the surfaces made conductive is inserted and held between those electrodes 22a and 22b. This diaphragm 24 is formed by sticking frame bodies 25a and 25a' formed in the same shape to both plate surfaces oppositely and uniting the diaphragm 24 to the frame bodies 24a and 25a'. At this time, the thicknesses of the frame bodies 25a and 25a' are set so that the electrodes 22a and 22b, and diaphragm 24 have gaps A and B of desired size, and the frame bodies 25a and 25a' are used as the spacers. Consequently, the frame bodies 25a and 25a' are formed thinly enough for application to a microphone, so an electrostatic type push-pull microphone with high performance is realized.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an electrostatic electroacoustic transducer that allows the gap between a fixed electrode and an imaging plate to be set easily and with high accuracy. be.

[Technical background of the invention and its problems]

Conventionally, static 1 type air acoustic conversion skins have been made into push-pull structures to reduce distortion.

It is particularly commonly used in headphones. However, in microphones, the gap between the fixed electrode and the diaphragm is usually extremely small, making the structure complex, and the parts and assembly accuracy must be extremely high, so it has not reached the stage of practical use. do not have.

The push-pull structure of conventional electrostatic electroacoustic transducers can be roughly divided into two types, as shown in FIGS. 1 and 3.

FIG. 1 shows a push-pull type headphone with a diaphragm 2 interposed between two fixed electrodes 1a and lb. In the figure, la and lb are fixed electrodes, 2 is a diaphragm, 3 is a frame on which the diaphragm 2 is stretched and supports it, and 4 is the diaphragm 2.
a spacer for regulating the gap size between the fixed electrode 1a and the fixed electrode 1a;
Reference numerals a and 5b designate a nickel resin layer attached to one side of the fixed electrodes 1a and 1b, and 6 a housing formed in a cylindrical shape.

In this device, the gap size between the fixed electrode 1a or 1b and the diaphragm 2 is regulated by the thickness of the frame 3 and the spacer 4. However, in order to apply this to a microphone, the thickness of the frame 3 and spacer 4 is set to Q, 1 m.
m or less, the mechanical strength of the frame 3 becomes smaller than the tension of the diaphragm 2, so as shown in FIG.
Due to the tension, a force is applied to the frame 3, causing the frame 3 to warp. This warpage causes the imaging plate 2 to easily separate from the frame 3, and also causes distortion in the diaphragm 2, resulting in problems such as a lack of product reliability and a significant drop in performance.

Next, FIG. 3 shows a conventional microphone configured in a push-pull type with diaphragms 12a and 12b arranged on the outside of a pair of fixed electrodes 11a and Ilb, respectively. In the figure, lla and flb are fixed dL 4fj, 12a,
12b is a diaphragm.

13a and 13b are annular frames that span the diaphragms 12a and 12b; 14a and 14b are spacers that regulate the gap between the fixed electrode 11a and Ilb and the diaphragms 12a and 12b; and 15a and 15b are vibration plates for one side. Frame 1 on plate 12b
3b, an acoustic phase-shifted acoustic transmission hole provided through the insulators 15a and 15b; 17, an acoustic resistance provided between the insulators 15a and 15b; and 18a and 18b, an elm plate attached to one side of the fixed electrode 11311b. 19 is a conductive housing formed in a cylindrical shape; 20 is a housing 1;
This is an insulating layer provided on the inner surface of 9.

In this device, diaphragms 12a and 12 are connected to the outside of a pair of fixed electrodes 11a and llb via spacers 14a and 14b.
By providing the spacers 14a and 14b, the frames 13a and 13b can be formed sufficiently large to stably hold the diaphragms 12a and 12b. The dimensions can be set small and with high precision.

However, in this structure, the diaphragm 12as12b is
By providing two diaphragms, the vibration system becomes heavier and the diaphragms 12a and 12b act separately in the high frequency range.

There are problems such as a marked deterioration in high-frequency characteristics and an increase in stiffness, resulting in a decrease in low-frequency response.

[Purpose of the invention]

This invention was developed to solve the above problems, and the screen surface of the imaging board can be stably held by a pair of frames, and the frame can connect the diaphragm and the fixed electrode. An object of the present invention is to provide an electrostatic electroacoustic transducer whose gap can be set small enough to be applied to a microphone.

[Summary of the invention]

The electrostatic electroacoustic transducer of the present invention is provided with a pair of frames attached to the screen surface of a diaphragm disposed between a pair of fixed electrodes, and the frames are set to a desired thickness and fixed. It is also used as a spacer to regulate the gap size between the electrode and the diaphragm.

〔Effect of the invention〕

According to this invention, by attaching a pair of frames to the screen surface of the diaphragm, the bending of the frames caused by the tension of the diaphragm can be canceled out, thereby stabilizing the diaphragm. Moreover, it can be held reliably and the precision of the product can be easily increased.

Further, by setting the frame to a desired thickness, the gap between the fixed electrode and the diaphragm can be set to an extremely small size.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to one drawing.

FIG. 4 shows an application of the present invention to a unidirectional microphone. In the figure, reference numeral 21 denotes a cylindrical conductive housing, and a pair of fixed electrodes 22a and 22b are disposed in the upper part of the housing 21. One fixed electrode 22a is electrically connected to the housing 21, and the other fixed electrode 22b is electrically connected to the electrode terminal 23. Between these fixed electrodes 22a and 22b, a disc-shaped diaphragm 24 whose surface is made of metal foil or resin film and which has been subjected to conductive treatment is inserted and held. As shown in FIG. 5, this diaphragm 24 is an annular frame 2 formed in the same shape as the screen surface.
The diaphragm 24 and the frames 25a, 25b are integrally formed by facing each other and attaching them using adhesive or other means.

At this time, the thickness of the frames 25a, 25b is adjusted in advance to a degree that can be applied to a microphone (0.1 mm or more) so that the gaps A, B between the fixed electrodes 22a, 22b and the diaphragm 24 have the desired dimensions. F') and also serves as a spacer.

On the other hand, a sound transmission hole 26a is provided on the bottom surface of the fixed polarization 22b.

The insulators 26 and 27 formed with 27a are acoustically connected.

Sound transmission holes 26B and 2 are provided between the insulators 26 and 27.
An acoustic phase shift circuit is constructed by interposing an acoustic resistor 28 so as to block the acoustic phase shift circuit 7a. Here, 29 is an insulating layer provided on the inner wall of the housing 21.

This device equalizes the mechanical strength of the pair of frames 25a and 25b and forms them with the same shape.

Since the forces that tend to bend the frames 25a and 25b due to the tension of the diaphragm 24 cancel each other out, the diaphragm 24 can be prevented from warping.

Therefore, with this configuration, the pair of frames 25a and 25b that support the sliding plate 24 can be made extremely thin enough to be applied to a microphone.
A high-performance IIE type push-pull microphone can be realized.

Moreover, since the diaphragm 24 can be tensioned uniformly, it is possible to easily improve the precision of the product, and also to reduce stiffness and improve response in the bass range.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without changing the gist.

In this invention, the diaphragm can be formed into a regular shape such as a circle or a square, or it can also be formed into an irregular shape.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a conventional electrostatic electroacoustic transducer configured as a headphone;
1 is a sectional view showing a conventional electrostatic push-pull electroacoustic transducer configured as a microphone, FIG. 4 is a sectional view showing an embodiment of the present invention, and FIG. 5 is a diaphragm and frame of the same embodiment. FIG. la, lb... Fixed electrode 2... Vibration plate 3.
...Frame 4...Spacers 5a, 5b
... Niretsukret layer 6 ... Housing 11a,
llb - Fixed electrodes 12a, 12b... Vibration plate 13a, 43b - Frame 14a,
14b...Spacer 15a, 15b...Acoustic phase shift circuit 16...Snow crushing transmission hole 17...Sound I resistance 18a
, 18b... Niletsklet layer I9... Housing 20... Insulating layer 21... Housing 22a, 22b... Fixed electrode l1 23... Electrode N element 24... Vibration plate 25a,
25b...Frame body 26.27...Acoustic phase shift circuit 2
6a, 27a...Acoustic transmission hole 28...Acoustic resistance 29...Insulating layer Fig. 1 9J2 Fig. 3 100MIbI'71b Fig. 4 Fig. 5Wi 1920, 1930, Japanese Patent Office Nagi Kazuo Wakasugi 1. Display of 41 patent applications No. 1987-099814 2 Name of the invention Silent 'It type (difference tone i conversion device 3, patent related to corrector neutrality, @jin (3 () 7) Higashi Saki Shibaura (Ki Co., Ltd. 4 Agent 5) Date of sending the amendment order (method) September 28, 1980 6, Amendment number 1 Column 7 for a brief explanation of the drawings in the detailed description, Contents of the amendment In the 14th line of page 8 of the specification of the present application, the part ``j'' is corrected to ``J in Figure 3''.

Claims (3)

[Claims] (1) Two fixed electrodes, a photographic plate interposed between these fixed electrodes, and a fixed electrode provided opposite to and attached to the screen surface of the photographic plate, and said fixed a m , = photographic plate. What is claimed is: 1. An electrostatic type 1-temperature sound/door conversion device characterized by comprising a pair of frames that define a gap size between the two frames and hold a photographing plate. (2) The electrostatic electroacoustic transducer according to claim 1, wherein the frame bodies of the two fils are formed into one shape having the same thickness. (3) The static type 1 electroacoustic transducer according to claim 11, wherein the diaphragm is formed by subjecting the surface of a resin film to one-section treatment.