JPH0255397A - Electromagnetic type sounding body - Google Patents

Abstract

PURPOSE:To prevent a sounding body from generating defective performance even when cracks are generated on a magnet at the time of molding the sounding body by completely surrounding the magnet at the time of forming a magnetic field part on a frame. CONSTITUTION:A coil is arranged around a center pole 15 on a plate 14 and a ring-like magnet 17 is arranged around the coil 16 to constitute the magnetic field part. The frame 22 having a cylindrical part 21 forming a step part 20 on its upper end is formed so as to cover the outer peripheral edge of the plate 14. At the time of forming the frame 22, the magnet 17 and the coil 16 on the plate 14 are simultaneously molded and only the center pole 15 is exposed to the upper surface of a molding part 23. Since the coil 16 and the magnet 17 in the magnetic field part are covered with the molding part 23, cracks or notches are not generated on the magnet 17, and even if the magnet 17 is cracked by a shock or the like, the sounding body can be prevented from generating an abnormal sound or defective performance due to the enter of the chips of the magnet 17 into a magnetic gap between a metallic diaphragm consisting of a diaphragm 24 and a suspension 25 supported by the cylindrical part 21 and the magnetic field part.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electromagnetic sounding body used for sound emitting (calls, notifications, alarms, etc.) in various industrial fields such as home appliances, automatic clocks, and automobile clocks. It is.

BACKGROUND OF THE INVENTION In recent years, small and thin electromagnetic sounding bodies that generate sound through acoustic vibrations have been attracting attention, and their structures are becoming more complex as they become more multifunctional.

Therefore, an example of a wash-resistant type sounding body mounted on a circuit board that we have proposed earlier will be explained with reference to the drawings.

FIG. 3A is a plan view of a conventional electromagnetic sounding body, and FIG. 3B is a sectional view taken along line A-0-B.

A magnet (permanent magnet) 3 and a plate (yoke) 6,
A coil 4 is fixed to a magnetic circuit consisting of a frame 6 that fixes the plate 5 to constitute a field section, and a metal diaphragm consisting of a diaphragm 8 and a suspension 9 with high magnetic permeability is inserted through a narrow gap 12. It is provided so as to be held at the upper end of the frame 6. The metal diaphragm is attracted and supported by the plate 6 in advance due to the DC magnetic field generated by the magnet 3. However, when an AC signal is applied to the coil 4 through the terminal 10, the resulting AC magnetic flux is superimposed, and the attraction force increases from the AC signal. The metal diaphragm vibrates and generates sound. The generated sound is amplified by the cavity 2 between the resonance cases 1 and is emitted to the outside through the sound emitting hole 11.

Here, since it is a wash-resistant type, a waterproof membrane 7 is provided on the upper surface of the frame 6 to which the metal diaphragm is attached, and two sound emitting holes 11 are provided at the lower side of the resonance case 1. Further, in order to directly mount the resonant case 1 on the board, the electrical coupling portion 13 between the lead wire and the terminal 1o is provided inside the resonant case 1 instead of outside.

Problems to be Solved by the Invention However, with such a structure, the magnet 3 cracks due to the resin pressure when the field part is inserted, and the magnet 3 is chipped or shattered during a drop test. This causes problems such as fragments of the magnet 3 entering the magnetic gap 12 or cracking of the magnet 3, resulting in poor performance.

The present invention aims to provide an electromagnetic sounding body that can solve these problems.

Means for Solving the Problem In order to solve this problem, the present invention has a structure in which the magnet is completely wrapped up when the field part is molded.

action The effect of this technical means is as follows.

That is, since the structure is such that the magnet is completely wrapped during molding of the field part, even if cracks occur during molding, the magnet can be prevented from chipping or shattering due to impact or the like.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, FIGS. 1 and 2.

14 is a plate having a center pole 16, a coil 16 wound in a ring shape around the center pole 16 on this plate 14, and a ring-shaped magnet 17 arranged around the outer periphery of this coil 16 to form a field section. It consists of Further, a conductive portion 19 is arranged on the plate 14 and is electrically connected to the end of the coil 16 and led to the terminal 18 .

A frame 22 is formed in these field parts and has a cylindrical part 21 which is formed to cover the outer peripheral edge of the plate 14 and has a stepped part 20 at the upper end. When the magnet 1 on the plate 14 is
A mold part 23 is formed in which the coil 16 is molded at the same time, and only the center pole 16 is exposed on the upper surface of this mold part 23.

The stepped portion 20 of the cylindrical portion 21 of the frame 22 holds the peripheral edge portion of a metal diaphragm 25 consisting of a diaphragm 24 made of a high magnetic permeability material coupled to the center thereof.

Furthermore, a waterproof membrane 26 is coupled to the upper surface of the metal diaphragm of the cylindrical portion 21 of the frame 22.

Further, the frame 22 is covered with a resonance case 27, which forms a cavity 28, and sound emission holes 29 are provided at two locations at the bottom of the resonance case 727.

When an AC signal is applied to the coil 16 through the terminal 18 in this configuration, the resulting AC magnetic flux is superimposed, and the attractive force changes according to the frequency of the AC signal, causing the metal diaphragm to vibrate and generate sound. do.

The generated sound is amplified by the cavity 28 of the resonance case 27 and is emitted to the outside through the sound emitting hole 29.

In addition, since the coil 16 and magnet 17 of the field part are completely covered by the mold part 23, the magnet 17 will not crack or chip, even if it is chipped due to impact etc. Effects of the Invention The present invention can prevent fragments of the magnet 17 from entering the magnetic gap between the metal diaphragm and the field part, causing abnormal noise or poor performance. By adopting a structure that completely envelops the magnet when forming the frame, even if the magnet cracks during molding, the magnet will not be chipped or shattered due to falling, vibration, heat, etc. Therefore, performance defects of the sounding body due to the field part will not occur at all.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an electromagnetic sounding body according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line C-0-D in FIG. 1, and FIG. 3 is a plan view of a conventional electromagnetic sounding body. FIG. 4 is a sectional view taken along line C-0-D in FIG. 3. . 14...Plate, 16...Center pole, 16...Coil, 17...Magnet, 18...Terminal, 2o... ... Stepped part, 21 ... Cylindrical part, 22 ... Frame, 23 ... Mold part, 24 ... Diaphragm, 26 ...・・Sanupension, 26・
...Waterproof membrane, 27...Resonance cake, 28
...Cavity, 29...Sound emission hole. Name of agent: Patent attorney Shigetaka Awano and 1 other person 1st
11 I4-Flate I5-Young-Hall 16-Coil 17゛°-Magnet tS-Ichiko 2θ-・Crotch 2I-・-Xi 1 Ozagi 22-7 Rem 23...Mold section? 4...-Diacus A D-1stition 26-Li water gland 27--~ Lost pigeon case 28- Morning event 29--In the past

Claims (1)

[Claims] A frame is formed by resin molding on a field part configured by arranging a magnet and a coil on a plate, at least the magnet is wrapped in a resin mold part, and a metal diaphragm is arranged on the cylindrical part of the frame. An electromagnetic sounding body covered with a resonant case.