JPS59876Y2 - sound generator - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sound generating device that generates an alarm sound in, for example, an alarm clock.

Conventional sound generators of this type have a fixed iron core, but unless the gap between the iron core and the diaphragm is kept constant, it is difficult to drive the diaphragm efficiently. Additional machining was required to increase the machining accuracy or to maintain the above-mentioned gap constant.

Furthermore, in the past, when assembling various parts, the force of adhesives, etc., or caulking was used, which made the assembly and component configuration complicated.

The present invention is intended to eliminate the above-mentioned conventional drawbacks, and embodiments thereof will be described below with reference to the drawings.

Reference numeral 1 denotes a yoke made of a magnetic material such as iron, 2 a ring-shaped magnet disposed on the upper surface of this yoke, and 3 a ring-shaped coil arranged concentrically inside this magnet.

A thin film-like diaphragm 5 is disposed above the magnet 2 via a ring-shaped spacer 4 made of a magnetic material.

An additional mass 6, which is thicker than the diaphragm 5 and has a size approximately equal to the inner diameter of the magnet 2, is fixed to the upper surface of the diaphragm 5 by spot welding or the like.

The diaphragm 5 has a predetermined spring constant and is made of magnetic stainless steel in this embodiment.

The additional mass 6 is a magnetic material (5 pcc is used in this embodiment).

), and by setting this diaphragm to appropriate dimensions, the mass of the oscillation system can be set to a predetermined value.

Note that when the diaphragm 5 is made of a magnetic material as in this embodiment, the diaphragm 5 alone is sufficient as long as the diaphragm is made thick to reduce the magnetic resistance.

By the way, yoke 1, magnet 2, spacer 4 and diaphragm 5
are simply magnetically attracted to each other by the magnetic attraction force of the magnet 2.

Reference numeral 7 denotes an iron core inserted through the center of the coil 3. By screwing this iron core into the yoke 1, the gap between the tip of the iron core and the lower surface of the diaphragm 5 can be adjusted to an optimum value. It's Nishide.

Reference numeral 8 denotes a casing fixed to the upper surface of the yoke 1. A hole 8a is formed in the center of the upper surface of the casing 8, and a resonance chamber 8b is formed above the diaphragm 5 to resonate and amplify the vibration sound.

8C... are a plurality of ribs formed protrudingly on the inner wall of the casing 8, the lower end surfaces of which are located slightly above the outer peripheral edge of the diaphragm 5.

Further, the leg portion 8d of the casing 8 is snap-connected to the hole 1C of the yoke 1.

Reference numeral 9 denotes a circuit board on which the sound generating device having the above structure is mounted, and the vertical bent portions lb, lb at both ends of the yoke 1 are fixed to this circuit board.

In addition, the yoke 1 and the circuit board 9 each have a small hole 1a,
A lead wire 3a of the coil 3 is drawn out from this small hole and connected to the circuit board 9 by soldering or the like.

After connecting the lead wire 3a, the small holes 1a and ga are sealed by pouring adhesive to prevent leakage of internal air.

10 is a synthetic resin bobbin around which the coil 3 is wound;
It is held using the magnetic attraction force of the magnet 2.

That is, the outer diameter of the lower flange 10a is larger than the upper flange 10b, which is approximately equal to the outer diameter of the coil, and smaller than the outer diameter of the magnet 2.

A locking portion 2a is formed on the inner peripheral portion of the lower surface of the magnet 2, with which the outer peripheral portion of the flange 10a engages.

This locking portion 2a is formed as an annular groove whose depth is approximately equal to the thickness of the flange 10a and whose outer diameter is approximately equal to the outer diameter of the flange 10a.

Therefore, the bobbin 10 is placed on the yoke 1 and the magnet 2
By fitting into this, the locking part 2a of the magnet engages with the outer periphery of the flange 10a on the lower side of the bobbin, so that the bobbin 10 is held by the magnetic attraction force between the magnet 2 and the yoke 1. This restricts the upward movement of the bobbin.

Therefore, there is no need to use adhesive or the like when attaching the bobbin 10.

By the way, when an inverted drive pulse signal of a predetermined period is supplied to the coil 3, the iron core 7, the diaphragm 5, the additional mass 6, and the spacer 4
, a loop-shaped magnetic path passing through the magnet 2 and the yoke 1 is formed, but the magnetic flux density changes due to the reversal of the magnetism of the yoke 1.
Due to this change in magnet density, the diaphragm 5 and the additional mass 6
vibrates.

Then, this vibration sound is resonated and expanded by the resonance chamber 8b,
It generates a large output sound.

Note that, instead of the spacer 4, a corresponding raised portion may be formed integrally with the magnet 2.

As described above, the present invention attracts and holds the yoke, magnet, and diaphragm to each other by the magnetic attraction force of the magnets, and also increases the diameter of the flange on the lower side of the bobbin to engage with the locking part of the magnet. Since the bobbin is held by a magnet in such a way that the bobbin is held together by a magnet, during assembly, all you have to do is place the bobbin with the coil wound on the yoke, the magnet, the spacer, and the diaphragm 5 in this order. The coils can be held in place without the need for adhesives or other force to fix the coils, making assembly extremely easy and manufacturing at low cost.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of an embodiment of the present invention. 1... Yoke, 2... Magnet, 2a...
...Locking part, 3...Coil, 5...
・Diaphragm, 7...Iron core, 8...Casing, 8b...Resonance chamber, 10...Coil bobbin, 10a, 10b... ...Flange.

Claims (1)

[Claims for Utility Model Registration] A bobbin in which the outer diameter of the lower flange is larger than the outer diameter of the upper flange, and a coil wound around the bobbin to an outer diameter approximately equal to the outer diameter of the upper flange. and an annular magnet having a center hole into which the coil fits and an outer diameter larger than the outer diameter of the lower flange, and an annular magnet formed on the lower surface of the magnet so that the outer periphery of the lower flange engages. a locking part that fits together, a diaphragm disposed on the top of the magnet, an iron core inserted through the center of the coil with its tip facing the diaphragm, and a vibration plate that suppresses the vibration noise of the diaphragm. The casing has a resonance chamber that expands the resonance, and a yoke made of a magnetic material disposed on the lower surface of the magnet, and the yoke, the magnet, and the diaphragm are attracted and held to each other by the magnetic attraction force of the magnet, and A sound generating device characterized in that the bobbin is held by the magnet by engaging a lower side and an outer peripheral portion of the flange with a locking portion of the magnet.