JPS6113678B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called ribbon-type electroacoustic transducer, and is particularly designed to suppress abnormal low-order and high-order vibrations of its diaphragm.

The present applicant had previously proposed technical content related to this type of electroacoustic transducer (Patent application No. 53-60842).
issue). First, the device of the prior application will be briefly described. FIG. 1 is a schematic vertical cross-sectional view of the main parts for explaining the device. In the figure, 1 and 2 are first and second magnets arranged symmetrically with polarity in the same direction; 3
and 4 are first and second magnetic pole plates provided on the N-pole surface of both magnets, 5 is a yoke joined across the S-pole surface, and 6 is integral with this yoke and made at a predetermined height. The center pole is shown, and as shown in the figure, the first and second magnets 1 and 2 are connected to the center pole 6.
Keep a certain distance on both sides of the
The second magnetic pole plates 3 and 4 extend inward from each magnet and are spaced apart from each other by a constant distance. Therefore, the first and second magnetic pole plates 3
A magnetic field is formed between the center pole 4 and the center pole 6, respectively.

In the case of this example, the inner surfaces of the overhanging portions of the first magnetic pole plate 3 and the second magnetic pole plate 4, that is, the portions corresponding to the corner positions of the left and right magnets, are formed into symmetrical L-shaped notches 7. A vibrating body 8 (this is a general term including a diaphragm, a conductor, a fixed plate, etc. described below) is arranged in these notches. As shown in FIG. 2, this vibrating body 8 has a rectangular fixing plate 9 made of a resin material, for example, with a rectangular punching hole 10 formed therein, and a diaphragm made of a thin resin film such as Mylar film or polyamide film on one side. 11 (vibration membrane), a metal layer such as a thin aluminum layer is deposited on the surface of the diaphragm 11, for example, by vapor deposition, and then photo-etched to form a conductor in a substantially elliptical spiral pattern. 12 (12a, 12b are forward and reverse paths, that is, operation lines for multiple threads). 13a and 13b are terminals for connecting lead wires to both ends of the conductor.

As shown in FIG. 1 and described above, such a vibrating body 8 is disposed between the first and second magnetic pole plates 3, 4 and the center pole 6, and the diaphragm 11 is provided with an oval shape in each of the above-mentioned magnetic fields. The operating lines 12a and 12b on both sides of the spiral conductor 12 are positioned respectively, and when an audio electrical signal is applied to the conductor 12, the diaphragm 11 is vibrated according to a well-known principle, and the electrical signal is converted into an acoustic signal. Also diaphragm 1
The acoustic signal applied to the conductor 1 can be extracted as an electrical signal from the terminal of the conductor 12. Incidentally, it is better to understand that this example is a case of a speaker, and such mounting itself is explained in detail in the description of the above-mentioned prior application.

By the way, in order to improve the conversion efficiency of the electroacoustic transducer as described above, the number of actuation lines 12a and 12b on both sides formed on the surface of the diaphragm 11 should be as small as possible in the portion facing the end surface of the center pole 6. It is desirable that the first and second magnetic pole plates 3, 4
It is natural from the directionality of each magnetic field between
(Figure 2) needs to be widened. However, the problem in this case is that low-order and high-order abnormal vibrations occur in the wide area when an electric signal is applied. In other words, since the space 11' in that range only follows the vibrations of the two-side operating lines 12a and 12b during driving, abnormal vibrations other than the original converted sound are likely to occur.

An object of the present invention is to construct a new means that can effectively avoid such problems, and thereby improve the characteristics of this type of electroacoustic transducer.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 5.

FIG. 3 is a perspective view showing an example of a drive unit structure of an apparatus according to the present invention, and corresponding parts to those in FIGS. 1 and 2 are given the same reference numerals and redundant explanation will be omitted. In the present invention, a column 14 made of a non-magnetic material is provided on one side of the diaphragm 11, that is, on the top side in the illustrated case, parallel to the above-mentioned space 11', separated by a predetermined gap, and facing the center pole 6 on the bottom side. It is being This support 14 has a cross-sectional shape similar to, for example, a heart shape, and is arranged between the first and second magnetic pole plates 3 and 4, and its fixing means are not shown, but it is attached to the drive unit structure or a cover that houses it. It should be understood that it is attached to a part of the

FIG. 4 is an enlarged vertical cross-sectional view of the main part orthogonal to the support column 14. In this example, a shallow downward U-shaped recess 15 is formed in advance in the longitudinal direction of the lower surface of the support support 14, and the recess 15 is On the other hand, the braking member 16 is inserted and fixed with adhesive or the like, and the braking member 1
6 and the above space 1 of the diaphragm 11
1' is brought into uniform contact with the surface.

The shape of the braking member 16 is, for example, a sixth shape.
It is made into a flat rectangular shape as shown in the figure, and the material is suitably flexible, such as nonwoven fabric, cloth cloth, or synthetic leather, and in particular, the surface in contact with the diaphragm has a fine brushed finish. If this is done, the contact will be soft and uniform in the contact state, and a satisfactory braking action will be achieved. However, it is up to you whether or not to join the braking member 16 into the recess 15 of the strut 14, and even if the lower surface of the strut 14 is flat, the braking member may be interposed between that surface and the space 11' of the diaphragm. It's easy to do. Note that, if necessary, an appropriate damping material may be provided between the end surface of the center pole 6 and the diaphragm 11.

Thus, according to the present invention, it is possible to overcome the disadvantages that occur when attempting to increase the electroacoustic conversion efficiency of this type of device as just described, namely, the abnormal low-order and high-order vibrations of the diaphragm that tend to occur when an electric signal is applied. can be almost suppressed, and therefore is extremely useful in improving the characteristics of the device. Note that it is possible to add a function as an equalizer depending on the design of the support, and the support can be used to select the frequency characteristics, high pressure level, etc. In any case, although the present invention has a relatively simple configuration, it can bring about excellent practical effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view of the main parts of an example of an electroacoustic transducer to which the present invention can be applied, FIG. 2 is a perspective view of its vibrating body, and FIG. FIG. 4 is an enlarged longitudinal cross-sectional view showing the main parts thereof, and FIG. 5 is a perspective view showing an example of a braking member. In the figure, 1 and 2 are the first and second magnets, 3 and 4
are first and second magnetic pole plates, 5 is a yoke, and 6 is a yoke.
is the center pole, 8 is the vibrating body, 9 is its fixing plate, 11 is the diaphragm, 11' is the space, 1
2 is a conductor, 12a and 12b are operating lines, 14
15 is a concave portion, and 16 is a braking member.

Claims (1)

[Claims] 1. A third magnetic pole is provided at a substantially central position between the first and second magnetic poles facing each other, and a diaphragm having a conductor is placed in the magnetic field created by the third magnetic pole and the first and second magnetic poles. At the same time, a support made of a non-magnetic material is provided on one side of the diaphragm, facing the third magnetic pole on the other side, and separating a predetermined gap substantially parallel to the surface of the diaphragm, and a support between the support and the diaphragm is provided. An electroacoustic transducer characterized by having a braking member made of a flexible material interposed therebetween.