JPS6011880B2 - Ribbon type electroacoustic transducer - Google Patents

Description

[Detailed description of the invention] The present invention relates to a ribbon-type string-air acoustic transducer.

In this electroacoustic transducer, for example, a ribbon type speaker is constructed by directing two magnets 1 and 2 with their one pole directed in different directions, and separating them at a predetermined distance, as shown in FIGS. 1a and 1b. A plate 3 is fixed to one end of these magnets 1 and 2, and yoke plates 4 and 5 are placed at the edge of the pond, and a ribbon-shaped diaphragm is placed in the magnetic field generated between these yoke plates 4 and 5. 6 is arranged so that its plane is parallel to the magnetic flux direction,
Its both ends are fixed to fixed terminals. Conventionally, this diaphragm 6 has been made of aluminum processed into a foil shape.

In order to cause the diaphragm to make a piston movement, there is a diaphragm made of aluminum foil in which ribs such as hexagonal pyramids are assembled to make the diaphragm rigid. With such a diaphragm, although a certain amount of piston motion could be expected, a more complete piston motion could not be expected.

Furthermore, processing such an aluminum foil diaphragm into a complicated shape is not only difficult in terms of processability but also expensive. Therefore, the present invention aims to solve this momme point, and provides a ribbon-type fin-air acoustic transducer that is easy to process and assemble, reduces costs, and allows the diaphragm to perform better piston motion. This is what we intend to provide.

In order to achieve this purpose, the ribbon-type electroacoustic transducer of the present invention has a vibrating part made of a beryllium thin film to increase rigidity, and an edge part made of a metal having high compliance. It is.

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

FIG. 2 is a perspective view of the main parts of an embodiment of the ribbon-type electroacoustic transducer according to the present invention, in which yoke plates are fixed to different poles of two magnets arranged at a constant interval. Yoke plates 7 and 8 are arranged with a predetermined distance between them, and a magnetic field is created between these yoke plates 7 and 8.

A ribbon-shaped diaphragm 9 is disposed between these yoke plates 7 and 8 along the longitudinal direction of the yoke plates so that its flat surface is parallel to the magnetic field. This diaphragm 9 includes a vibrating section 10 made of a beryllium thin film, and curved sections 11 having a U-shaped cross section in a direction perpendicular to the longitudinal direction of the diaphragm 9 at both ends of the vibrating section 10. The edge portion 12 is made of aluminum foil and is fixedly held by fixed terminals 13, 13. In such a configuration, the current flows through the diaphragm 9
When the magnetic flux flows in the direction A, the diaphragm 9 receives a force proportional to the current in the direction C, and the diaphragm 9 vibrates in a direction perpendicular to its plane in response to the electric signal, producing sound. It will be done. Next, an example of a method for manufacturing the diaphragm 9 will be explained using FIGS. 3a to 3d.

That is, as shown in FIG. 3a, an aluminum plate 14 with a thickness of about 10 mm is prepared, and beryllium is applied to the aluminum plate 14 by means of vacuum bonding, for example, with both ends covered with masks 15. A beryllium film 16 having a thickness of about 9 to 10 rms is formed on the surface of the aluminum plate 14 exposed from the mask 15.

As shown in FIG. 3b, by removing the mask 15, an aluminum plate 14 is obtained with a beryllium film 16 formed on the portions excluding both end regions.

As shown in FIG. 3c, a photoresist is coated on the back surface of the aluminum plate 14 where the beryllium film 16 is not formed, and the photoresist is overlapped with the beryllium film 16 on the back surface of the region where the beryllium film 16 is not formed. Selective exposure and development are performed in order to leave the photoresist in a region that extends slightly toward the center to the extent that a portion of the photoresist is formed.

Then, using the remaining photoresist as a mask, the exposed aluminum plate 14 is removed with an etching solution such as a sodium chloride (50%) solution, and then the photoresist is removed with xylene or the like. As shown in FIG. 3d, the aluminum plate 14 formed at both ends of the beryllium film 16 is pressed to form a bent portion 17 having a U-shaped cross section in a direction perpendicular to the longitudinal direction.

FIG. 4 is a perspective structural view showing an embodiment of the diaphragm used in the ribbon-type electroacoustic transducer according to the present invention. A beryllium (Be) film 2 is placed on the surface except for both ends.
0 is formed on the diaphragm. Next, an example of a method for manufacturing the diaphragm shown in FIG. 4 is shown in FIGS. 5a to 5c.

That is, an aluminum plate 18 with a thickness of about 10 mm is prepared, both ends of this aluminum plate 18 are covered with a mask 22, and beryllium is vapor-deposited by means such as summer vapor deposition. Approximately 2-3 on the surface
Forming a beryllium film 23 having a film thickness of 1.5 m {5th
Figure a}. Then, by removing the mask 22, an aluminum plate 18 having a beryllium film 23 formed only in the central portion is obtained. {Figure 5b}. The aluminum plate 18 at both ends exposed from the beryllium film 23 is pressed to form a bent portion 24 having a U-shaped cross section in a direction perpendicular to the longitudinal direction.
is formed to constitute an edge portion. The characteristics of the diaphragm manufactured as described above will be described below.

The Young's modulus (E) of beryllium is about 4 times larger than that of aluminum, and the density (p) is about 0. Since it is as small as the trumpet, E/p, which determines the resonance frequency, becomes about 2.5 times larger.

This means that the width of the movement area of the piston movement of the diaphragm is approximately 2.5 times that of aluminum. Furthermore, even when a beryllium film is formed on the aluminum plate surface, the composite Young's modulus is 1.8 times, which increases the width of the movement range of the piston motion of the diaphragm, making it ideal for general playback bands. Piston movement is possible. Furthermore, since the edge portions at both ends of the diaphragm are made of aluminum, which is a metal with high compliance, the above-mentioned piston movement can be performed even better. Furthermore, since the edge parts 12, 12 are electrically connected to the fixed terminals 13, 13 to which electric signals are supplied, they also have lead parts that supply electric signals to the vibrating part formed of the beryllium film. It is used for both purposes. Therefore, there is no need to provide a separate lead wire or to make a connection between the lead wire and the diaphragm, which is advantageous in terms of cost and ease of assembly. The problem of lead wire breakage is completely eliminated. Note that in the embodiment shown in FIG. 2, the vibrating section 1 made of beryllium
In the above description, the vibration part has a flat plate shape, that is, a hexagonal pyramid, and has no ribs, but ribs or corrugations that increase rigidity may be formed in the vibrating part.

In this case, productivity can be improved by first forming ribs on the surfaces of the aluminum plates 14 and 18 in advance, and then forming the beryllium film 20 on the surfaces of the aluminum plates 14 and 18 by means such as vapor deposition. Furthermore, in the above embodiments, the diaphragm is formed using an aluminum plate as a base material in order to improve the conformance of the edge portion, but the present invention is not necessarily limited to this aluminum plate. Superior metals with other conformance,
Of course, it may be made of metal such as copper.

A curved portion is formed in one area of this edge to improve the piston motion, but the number of curved portions formed is not limited and may not be formed at all. Good too. As described above, the ribbon type electroacoustic transducer according to the present invention has the advantage that it can exhibit good piston motion and is excellent in ease of processing and ease of assembly.

[Brief explanation of the drawing]

1A and 1B are schematic diagrams showing a ribbon-type speaker, FIG. 2 is a perspective view of essential parts of a ribbon-type speaker which is an embodiment of the ribbon-type electroacoustic transducer according to the present invention, and FIGS. d is a cross-sectional process diagram showing one embodiment of the manufacturing method of the diaphragm used in the IJ pump type speaker shown in Fig. 2, and Fig. 4 is another embodiment of the diaphragm used in the ribbon type speaker according to the present invention. FIGS. 5A to 5C are cross-sectional process diagrams showing an embodiment of the method for manufacturing the diaphragm shown in FIG. 4. 1, 2... Magnet, 3... Plate, 4, 5, 7, 8...
...Yoke plate, 6,9...Diaphragm,
1-0... Vibrating part, 11, 17, 19, 24.
...bent part, 12, ... edge part, 13 ... fixed terminal, 14, 18 ... aluminum plate, 15, 22 ...
Mask, 16, 20, 23... beryllium film. Figure 1 Figure 5 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A diaphragm comprising an edge portion formed of a metal having high compliance at both longitudinal ends of a vibrating portion formed of beryllium, and a diaphragm having an edge portion formed of a metal having high compliance, and connecting both ends of the diaphragm through the edge portion. a pair of fixed terminals that are electrically connected to the edge portion, which holds the diaphragm and also serves as a lead portion; and a pair of fixed terminals that generate a magnetic field in a direction perpendicular to the longitudinal direction of the diaphragm and parallel to the plate surface. A ribbon-type electroacoustic transducer comprising: a yoke plate; 2. A vibrating section in which the diaphragm is made of a beryllium film;
2. The ribbon-type electroacoustic transducer according to claim 1, further comprising an edge portion formed of a metal film having high compliance and connected to an end portion of the vibrating portion. 3. The diaphragm includes a diaphragm base portion in which an edge is formed at the end of a metal film having high compliance, and a vibrating portion made of a beryllium film integrally formed on an intermediate portion of the base portion. A ribbon-type electroacoustic transducer according to claim 1, characterized in that: