JP3340577B2 - Prevention of short circuit between coil and yoke in electromagnetic sound generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic sounding body for generating a sound by vibrating a diaphragm by a magnetic circuit having a coil and a magnet arranged on a yoke. It relates to a short prevention structure.

[0002]

2. Description of the Related Art As shown in FIGS. 6 and 7, an electromagnetic sounding body is composed of a disk-shaped yoke 2 having a center pole portion 2a projecting in the center, and a coil 4 and a ring arranged concentrically thereon. The vibrating plate 8 is caused to vibrate by a magnetic circuit composed of the magnets 6 in a shape of a circle, thereby generating sound. The coil 4 of the electromagnetic sounding body has been electrically connected to the coil terminal 4a by soldering to a substrate 10 provided below the yoke 2 in order to establish an electrical connection with the outside.
As shown in FIG. 8, the coil wire constituting the coil 4 is composed of a conductor 12 of copper or the like, an insulating layer 14 and an adhesive layer 16 formed on the outer periphery thereof. For this reason, if the coil terminal 4a shown in FIG. 7 is pulled and loosened or rubbed to guide it toward the substrate 10, as shown in FIG.
Then, the insulating layer 14 is broken and the conductor 12 is exposed. When the exposed conductor 12 comes into contact with the yoke 2, the coil 4 and the yoke 2 are short-circuited, which hinders sound generation.

Conventionally, the following countermeasures have been taken to prevent the above short-circuit failure. That is, by using a bobbin 18 made of plastic as shown in FIGS. 10 and 11, or by providing an insulating spacer 20 between the coil 4 and the yoke 2 as shown in FIGS. The yoke 2 was not touched.
As shown in FIGS. 14 and 15, the coil terminal 4a
In some cases, an adhesive 22 is applied to the substrate to insulate and fix it, thereby preventing a short circuit.

[0004]

When the bobbin 18 is used as shown in FIGS. 10 and 11, a mold is required for plastically molding the bobbin 18, and maintenance of the mold is also required continuously. turn into. Also,
When assembling, in order to prevent the bobbin 18 from rising, the bobbin 18 is attached after applying an adhesive to the yoke 2 and, at this time, a projecting guide portion projecting from the lower surface of the bobbin 18 as shown in FIG. 18a is inserted into the guide hole 2b of the yoke 2 and the guide hole 10a of the substrate 10, and after the adhesive is dried, the guide portion 18a is formed on the lower surface side of the substrate 10.
Was fixed by heat caulking. As described above, when the bobbin 18 is used, there are many problems such as an increase in the cost and maintenance of the mold, an increase in the number of assembling steps, and an increase in the cost due to them.

[0005] When the insulating spacer 20 is used as shown in FIGS. 12 and 13, a pressing die for forming the insulating spacer 20 is required. The application of the adhesive and the drying operation in a drying furnace are also required. Further, since the disc-shaped insulating spacer 20 has no portion interposed between the center pole portion 2a of the yoke 2 and the inner diameter portion of the coil 4, the inner diameter portion of the coil 4 cannot be protected. In addition, due to the generation of static electricity, the insulating spacers 20 sometimes overlap with each other during assembly, making it impossible to remove the spacers or attaching dust. As described above, even when the insulating spacer 20 is used, the workability is poor due to the mold, the adhesive, the cleaning, the static electricity, and the like, and there are problems in man-hour, yield, and cost.

Further, when the adhesive 22 is used as shown in FIGS. 14 and 15, variations in the amount of application by the dispenser and scattering of the adhesive, floating of the magnet 6 caused by these causes, and the It requires a lot of work such as coil short due to uneven thickness of the adhesive due to variation, necessity of drying work, etc., and there are problems in man-hour, yield, and cost.

[0007] In all of these measures, an adhesive is used, but if the drying is not sufficient, poor curing may occur.

[0008] The present invention has been made in view of the above problems,
The purpose is workability, without using special materials,
An object of the present invention is to provide a structure for preventing short-circuit between a coil and a yoke in an electromagnetic sounding body, which improves reliability and yield and reduces man-hours and cost.

[0009]

Means for Solving the Problems] short prevention structure of the coil and the yoke in the electromagnetic sound generator of the present invention, the cover
A diaphragm supported inside the cover, a yoke,
A coil and a magnet arranged on a yoke, and the cover
And an end of the coil of the coil
And a substrate to which is connected ,
Forming an insulating coating on the entire surface of the yoke,
It insulates between the coil and the yoke and the base.
It is characterized in that it is insulated from the board .

[0010]

The outer periphery of the yoke according to the present invention is covered with an insulating film. For this reason, even if a coil contacts a yoke, it does not electrically conduct and it can prevent short-circuiting reliably. In particular, since the insulating film is formed by vapor-phase coating, the edges and the like are evenly coated as well as the flat portions, and the magnets and the like installed on the yoke do not float, and the magnets and the like do not float. Adhesion at the time of bonding can be also improved.

[0011]

1 is a cross-sectional view of an electromagnetic sounding body showing a short prevention structure according to an embodiment of the present invention. This electromagnetic sounding body includes a cylindrical cover 24, a diaphragm 26 supported inside the cover 24, and a center pole portion 2 protruding from the center.
A disk-shaped yoke 28 is arranged so that 8a faces the diaphragm 26, a coil 30 and a magnet 32 are arranged concentrically on the yoke 28, and an opening below the cover 24 is closed. And a substrate 34 that supports the yoke 28 and the like and to which the coil terminals of the coil 30 are connected.

In the present embodiment, the surface of the yoke 28
As shown in FIGS. 2 and 3, the insulating film 36 is formed by a vapor phase coating which is one of chemical vapor deposition.
As shown in FIG. 4 and FIG.
When 0 is attached, an insulating coating 36 is interposed between the coil 30 and the yoke 28, and these are insulated. Since the entire surface of the yoke 28 is covered with the insulating coating 36, the body of the disk-shaped yoke 28 and the coil 3
In addition to providing insulation between the center pole portion 28a and the center pole portion 28a of the yoke 28 and the inner diameter portion of the coil 30, the insulation between the center pole portion 28a and the center pole portion 28a This prevents the inner diameter of the coil 30 from being damaged. Also, since the yoke 28 and the substrate 34 are also insulated by the insulating coating 36 formed on the lower surface of the yoke 28, the connection between the coil terminal and the substrate 34 is
Can be reliably insulated even if it is provided on the upper surface of the.

In the vapor phase coating for forming the insulating film 36, the coating on the sharp corners or edges of the adherend, which has been difficult with the conventional liquid coating or powder coating, is performed uniformly like a flat surface. It is a technique that can be. In addition, the coating thickness can be easily controlled and has many excellent features such as moisture proof, rust proof, and corrosion proof. For this reason, this vapor phase coating is most suitable for coating a three-dimensional structure such as the yoke 28 made of a soft and easily corrodable special metal.

In this embodiment, the coil 30 formed by being wound in advance is attached to the yoke 28, but the coil 30 and the yoke 28 are reliably insulated by the insulating coating 36. Therefore, the coil 30 can be formed by directly winding a coil wire around the center pole portion 28a of the yoke 28.

[0015]

According to the present invention, the insulation between the coil and the coil is prevented by forming an insulating coating on the surface of the yoke. This eliminates the need for an extra space or member as in the case of preventing short-circuiting due to a spacer or an adhesive, thereby improving workability and reliability.

Further, since the bobbin, the insulating spacer, and the like can be eliminated, the space in the cover can be effectively used, and the electromagnetic sounding body can be reduced in size and thickness.

Further, the coil can be wound directly around the yoke, so that the assembling work for bonding the coil and the yoke formed in advance can be omitted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electromagnetic sounding body showing a short prevention structure according to an embodiment of the present invention.

FIG. 2 is a perspective view of the yoke shown in FIG.

FIG. 3 is a front view of the yoke shown in FIG.

FIG. 4 is a perspective view showing a state where a coil and a magnet are attached to the yoke shown in FIG. 2;

FIG. 5 is a sectional view of a yoke and the like shown in FIG. 4;

FIG. 6 is a perspective view showing a conventional yoke and coil.

7 is a sectional view of a conventional electromagnetic sounding body in which the yoke shown in FIG. 6 is incorporated.

FIG. 8 is a sectional view of the coil wire shown in FIG. 6;

FIG. 9 is a cross-sectional view of the coil wire showing a state where the coating of the coil terminal portion shown in FIG. 6 has been peeled off.

FIG. 10 is a perspective view showing a conventional short prevention structure using a bobbin.

11 is a cross-sectional view of an electromagnetic sounding body using the structure shown in FIG.

FIG. 12 is a perspective view showing a conventional short prevention structure using an insulating spacer.

13 is a sectional view of an electromagnetic sounding body using the structure shown in FIG.

FIG. 14 is a perspective view showing a conventional short prevention structure using an adhesive.

15 is a sectional view of an electromagnetic sounding body using the structure shown in FIG.

[Explanation of symbols]

 28 Yoke 30 Coil 36 Insulation coating

Claims (1)

(57) [Claims] A cover, and a vibration supported inside the cover.
A moving plate, a yoke, a coil and a coil disposed on the yoke,
Cover the lower opening of the cover with the magnet
A substrate to which a coil terminal of the coil is connected , comprising: an insulating film formed on the entire surface of the yoke;
It insulates between the coil and the yoke and the base.
A structure for preventing short-circuit between a coil and a yoke in an electromagnetic sounding body, characterized in that insulation is provided between the coil and the yoke.