JPS6343518Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electromagnetic sounding device that can be attached to small products such as watches, lighters, and accessories.

Conventionally, this type of electromagnetic sound device was published in U.S. Publication No. 54-34558.
As shown in Figure 1 of the publication, an iron core 5 is screwed into the center of a yoke 1, a coil 6 and an annular magnet 7 are arranged around it, and a spacer 9 with a diaphragm 10 attached to the magnet is attached with adhesive. Although it is fixed at
When using adhesive, the adhesive is liquid and depending on the type,
Liquid mixing is required, pot life management is required, curing time is generally long, and depending on the type of adhesive, heating is required, resulting in poor workability. Due to variations in the gap dimensions between the diaphragm, magnet, and iron core, variations in the output sound pressure and frequency band become large, and adjustment work for the threading of the iron core is required, and the space surrounded by the diaphragm, magnet, and iron core has a limited spatial capacity. The resonant frequency fluctuates greatly. Furthermore, one of the major fluctuation factors is the fluctuation in the amount of adhesive that protrudes from the joint, and controlling this amount is extremely troublesome in mass production.

In order to solve the above-mentioned drawbacks, as shown in FIG. 2 of the above-mentioned publication, the coil and magnet are clamped between the folding member 14 and the folding member 15 of the casing 11, and the diaphragm 10 is fitted into the recess 16 in the surface of the upper folding member 14. However, folding the top and bottom of the housing 11 is cumbersome and difficult to assemble, and it is difficult to achieve dimensional accuracy, and the above-mentioned drawbacks regarding output sound pressure and frequency band are not solved, and parts with complex shapes are difficult to achieve. It was necessary.

In view of the above-mentioned drawbacks, the purpose of this invention is to improve the output sound pressure and frequency band by making it easy to assemble by fixing the iron core to the yoke in one place without using adhesives. An object of the present invention is to provide an electromagnetic sounding device.

The features of this invention include a yoke with an annular magnet placed on its top surface, an iron core fixed to the yoke at the center of the magnet,
It has a coil fitted around the outer periphery of the iron core and a fixing plate that engages with the iron core, and by fixing the iron core to the yoke,
The yoke, magnet, iron core, and fixed plate are integrated.

The present invention will be explained below with reference to illustrated embodiments. 1st
2 shows a first embodiment of the electromagnetic sound device, in which an iron core 3 fitted with a coil 2 is fixed at the center of a disc-shaped yoke 1 with an insulating plate 4 interposed between them, and a ring-shaped plastic ring is attached to the yoke around the iron core 3. A magnet 5 is placed thereon and fixed integrally with an annular fixing plate 6 engaged with the iron core 3, and a diaphragm 7 made of a highly elastic material is placed on the diaphragm holding step 5a of the plastic magnet 5 to form a diaphragm. A movable piece 8 made of soft magnetic material fixed to the upper surface by spot welding or the like is attracted by a magnet 5 to hold the diaphragm.

A through hole is bored in the center of the disc-shaped yoke,
The boss portion 3a of the iron core 3 is press-fitted.

The iron core 3 has a boss portion 3a as shown in FIG.
Stepped portion 3 where the insulating plate 4 and fixing plate 6 are engaged
b, 3c are formed, and the outer periphery to which the coil 2 is fitted is insulated with a synthetic resin coating or the like.

The annular plastic magnet 5 is injection molded using magnetic powder such as ferrite and plastic material, and has the diaphragm holding step 5a on the top surface, another step 5c above the center hole 5b, and the diaphragm 7. A step portion 5d for forming a gap is formed respectively.

The insulating plate 4 and the fixed plate 6 are made of austenitic stainless steel or phosphorescent steel, which are non-magnetic and highly elastic materials, and are engaged with the iron core 3. The insulating plate 4 is made of a soft magnetic material such as iron, and if a surface-treated steel plate with an insulating film painted and baked on the surface is used, the cross-sectional area of the magnetic path is increased and the thickness of the yoke can be reduced, which is advantageous for thinning. It is. The fixing plate 6 may also be subjected to the same insulation treatment as described above so that the insulating plate and the fixing plate have a bobbin function.

When the electromagnetic sound generating device is constructed and assembled as described above, the annular plastic magnet 5 is placed on the yoke 1, and the fixing plate 6 is placed on the other stepped portion 5c of the plastic magnet 5. The insulating plate 4 and the fixing plate 6 are engaged, and the boss portion 3a of the iron core 3, into which the coil 2 is fitted, is press-fitted or caulked into the through hole of the yoke 1, and the upper surface of the plastic magnet 5 has a stepped portion 5a for holding the diaphragm. The assembly is completed by placing the diaphragm 7 on top.

Therefore, there is no need for adhesives that are difficult to work with, and parts such as magnets are positioned and fixed with a simple assembly process in which the iron core 3 is press-fitted or crimped into the yoke 1, resulting in a quick assembly process. is completed and assembly is extremely easy.

Further, the annular plastic magnet 5 can be easily manufactured into a complex shape by injection molding, and can be manufactured in large quantities at low cost, and the shrinkage rate during molding is 0.2 to 0.4% and 15 to 30% when forming a sintered ferrite magnet. It is extremely small compared to sintered products, has highly accurate dimensional characteristics, has less bending and deformation, can ensure dimensional accuracy on the micron order, has fewer cracks and chips found in sintered products, and can be easily thinned. It is.

Furthermore, the plastic magnet 5 is precisely positioned on the yoke 1 by the engagement of the other step part 5c and the fixing plate 6, and since no adhesive is used, the plastic magnet 5 does not stick out, and the magnet 5, the yoke 1, the iron core 3, and the diaphragm The capacity of the space A formed by 7 becomes constant, and the resonant frequency also becomes constant. Also, variations in the gap between the iron core 3 and the diaphragm 7 are small because the dimensional accuracy of the plastic magnet 5 is high.
A product with stable quality and less variation in output sound pressure and frequency band can be obtained.

4 and 5 show a second embodiment, in which a yoke case 9 in which a yoke and a case are integrated is provided, and a groove 5 is formed in the upper surface of the plastic magnet 5 in the diametrical direction.
Arms 6a, 6a extending from the fixing plate 6 are fitted into the fixing plate 6.

When the groove 5e and the arm portion 6a are formed and fitted together as described above, the center hole 5b of the plastic magnet 5 can be formed with a smaller diameter than in the first embodiment, and the magnetic force can be increased. can.

FIGS. 6 and 7 show a third embodiment, in which a fixing plate 6 is formed into a flange shape with a step 6b, and the center part is fitted into the center hole 5b of the magnet 5. The magnet may be an annular sintered ferrite magnet that cannot be formed into a complicated shape.

8 and 9 show a fourth embodiment, in which the fixed plate 6 is formed of a disk having approximately the same shape as the magnet 5, and the insulating plate 4
The outer diameter of the magnet 5 is formed to fit into the inner diameter of the center hole 5b of the magnet 5, and the magnet is positioned with an insulating plate.
The magnet has a built-in ferrite magnet.

Since the present invention is constructed as described above, the construction is simple, and by fixing the fixed plate, coil, and insulating plate to one place of the iron core where they are engaged and fitted, to the yoke, the magnet is positioned and fixed to the yoke and integrated. It is an electromagnetic device that has excellent practical effects, such as easy assembly, significantly improved assembly and workability, less variation in frequency band and output sound pressure, easy miniaturization and thinning, and cost reduction. A sounding device can be provided.

[Brief explanation of the drawing]

Figures 1 and 2 are the first embodiment of the electromagnetic sound device of the present invention, Figure 1 is a cross-sectional side view, Figure 2 is a plan view of the fixed plate, and Figure 3 is the iron core, fixed plate, coil, and insulating plate. The exploded side views of FIGS. 4 and 5 show the second embodiment of the present invention, and FIGS. 6 and 7 show the third embodiment of the invention, and FIGS.
Figure 9 shows the fourth embodiment of the same, and Figures 4, 6, and 8
The figures are cross-sectional side views of the electromagnetic sound device, Figures 5 and 7.
9 are plan views of the fixing plate. 1...Yoke, 2...Coil, 3...Iron core, 5
...Annular magnet, 6...fixing plate, 7...diaphragm plate.

Claims (1)

[Scope of utility model registration request] It has a yoke on which an annular magnet is placed, an iron core fixed to the yoke at the center of the magnet, a coil fitted around the outer periphery of the iron core, and a fixed plate engaged with the iron core,
An electromagnetic sounding device that integrates the yoke, magnet, iron core, and fixed plate by fixing the iron core to the yoke.