JP6032984B2 - Electromagnetic acoustic transducer for earphone - Google Patents

Description

  The present invention relates to an electromagnetic acoustic transducer for earphones, and more particularly to an electromagnetic acoustic transducer for earphones having good total harmonic distortion characteristics.

  In recent years, due to technological advances, music players of the size that fits in the pocket are generally sold at prices that anyone can purchase, and mobile phones and smartphones also function as such music players. As a result, the music of each person's favorite etc. is recorded on these music players and mobile phones, etc., and it is possible to touch the sight enjoyed while commuting to work, going to school or during breaks using earphones. Has become very large.

In recent years, sound leakage has occurred with earphones in earphones, so when used in public places (in trains, buses, etc.), this sound leakage can cause trouble for others. , on the other hand, large-type of head horn, excellent sound quality, and include, but are not sound leakage, in order to become completely cover the ear with large, been shunned from the evil of the selfish use in public places, which both have crowded As a result, sealed ear canal insertion type earphones have become mainstream.

As an example of the structure of an acoustic conversion device for an ear canal insertion type earphone, an electromagnetic type acoustic conversion device can be cited. This acoustic conversion device balances the movement of a mechanical system (a diaphragm with a movable iron piece) in a magnetic circuit. Therefore, good conversion efficiency (conversion efficiency from electricity to mechanical motion) can be obtained, which has the effect of reducing current consumption and extending the battery life of the music player, Other acoustic transducers also have the effect of making it possible to adopt a completely sealed structure that makes it impossible for the basic structure to adjust the sound quality.

  Patent Document 1 discloses an example of an electromagnetic acoustic transducer as shown in FIG. 1, which includes a movable iron piece 1 fixed to a diaphragm 2 having a restoring force and a magnet 3. In a magnetic circuit composed of a magnet 3, a coil 4 and a pole piece 5 facing each other, the diaphragm 2 to which the movable iron piece 1 is attached is made to have an opposite force between the attraction force by the magnetic flux penetrating the diaphragm 2 and the restoring force of the diaphragm. Thus, even a slight change in magnetic flux (change in electrical signal) in the magnetic circuit can be converted into a mechanical motion of the movable iron piece 1.

JP 2002-55683 A

  In general, ear canal insertion type earphones need to be fitted to everyone regardless of gender or age group, and large ear owners can cope by preparing a large earplug. In order to fit the owner of a small ear, the outer diameter of the diaphragm inevitably has to be reduced to, for example, φ13 or less.

  However, the conventional electromagnetic type acoustic transducer as shown in FIG. 1 has an advantage that it can be made with a simple component structure, but because of its simple structure, when it is miniaturized while maintaining high efficiency, it is large. The diaphragm is greatly curved as compared with the above, and there is a drawback that the total harmonic distortion increases.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and can maintain high efficiency even when downsized, and is an electromagnetic type for an earphone having good total harmonic distortion characteristics. An acoustic conversion device is provided.

That is, the present invention includes a cylindrical yoke, a diaphragm fixed to the opening surface of one end of the yoke, a movable iron piece fixed on the diaphragm, and a base provided on the other end of the yoke. An electromagnetic acoustic transducer comprising a pole piece projecting in a columnar shape toward a diaphragm, a coil wound around the columnar portion of the pole piece, and a magnet disposed so as to surround the coil There,
An electromagnetic acoustic transducer for an earphone characterized in that a diaphragm is fixed to an opening surface of one end of a yoke via a disc-shaped resin sheet whose shape corresponds to the entire shape of an edge at one end of the yoke. .

  In the electromagnetic acoustic transducer for an earphone according to the present invention, it is preferable that the outer diameter of the diaphragm is φ13 or less.

Further, resin sheet, it is if the response to the size and shape of the opening surface of the yoke end, there is no permissible.

  Furthermore, the resin sheet is preferably thermoformed.

  According to the present invention, high efficiency can be maintained even if the size is reduced, and it has a good total harmonic distortion characteristic despite the fact that the diaphragm is greatly curved as compared with a large size. An electromagnetic acoustic transducer for an earphone can be provided.

It is sectional drawing which shows an example of the conventional electromagnetic type acoustic transducer. It is a partially expanded sectional view which shows the attachment state of the diaphragm in an example of the conventional electromagnetic type acoustic transducer. It is a partially expanded sectional view which shows the attachment state of the diaphragm in the electromagnetic type acoustic transducer which concerns on the reference example of this invention. It is a perspective view which shows the structure of the electromagnetic type acoustic transducer which concerns on Embodiment 1 of this invention. It is a graph which shows the frequency characteristic of the electromagnetic acoustic converter which concerns on Embodiment 1 of this invention. It is a graph which shows the total harmonic distortion characteristic of the electromagnetic acoustic converter which concerns on Embodiment 1 of this invention.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

  The basic structure of the electromagnetic acoustic transducer for earphone of the present invention is the same as that of the prior art.

  That is, as shown in FIG. 1, the basic structure of the device of the present invention is a cylindrical resin or metal yoke 6, a diaphragm 2 fixed to an edge 7 on the opening surface of one end of the yoke 6, A movable iron piece 1 fixed on the diaphragm 2, a pole piece 5 having a part projecting from the base 8 provided at the other end of the yoke 6 toward the diaphragm 2, and the pole piece 5 The coil 4 is wound around the columnar portion, and the magnet 3 is disposed so as to surround the coil 4.

  In the electromagnetic acoustic transducer according to the prior art, as shown in FIG. 2, the diaphragm 2 is directly fixed to the edge 7 on the opening surface of one end of the yoke 6.

On the other hand , the inventors of the present invention repeated various experiments. First , as shown in FIG. 3, the diaphragm 2 having an outer diameter of approximately φ13 or less is formed on the edge 7 of the opening surface of one end of the yoke 6 with resin. It was fixed through a sheet 9.

  Examples of the material for forming the resin sheet 9 include polyethylene terephthalate (PET) resin, but are not limited thereto as long as the thickness can be finely adjusted. In general, since the diaphragm 2 is made of a material having high hardness, if a resin sheet 9 having a high hardness is used, a resonance phenomenon may occur. Therefore, the resin sheet 9 is formed. As the resin for this, a resin having a very high hardness is not preferable.

  Further, the thickness of the resin sheet 9 depends on the outer diameter of the diaphragm. For example, when the outer diameter of the diaphragm is φ13 or less, a range of 9 μm to 16 μm can be given, and the thickness is out of this range. In this case, the desired effect cannot be obtained.

Meanwhile, as the shape of the resin sheet 9, as is apparent in FIG. 3, it has a washers shape corresponding to the planar shape of the edge 7 at one end of the yoke 6.

  The diaphragm 2 to which the movable iron piece 1 is fixed is pulled toward the magnet 3 and the pole piece 5 by the attractive force from the magnet 3 and is supported by the edge 7. In particular, an adhesive or the like is not necessary.

Embodiment 1 (reference example)
Then the inventors of the present invention, the shape of the resin sheet 9, instead of the washers shape corresponding to the shape of the edge 7, as shown in FIG. 4, the overall shape of the edge 7 at one end of the yoke 6 was that of the corresponding disk-shaped.

As described above, the electromagnetic acoustic transducer for earphone of the present invention has been found to solve the problems of the prior art and exhibit excellent characteristics.

That is, the acoustic conversion device according to the first embodiment (hereinafter,. Simply as "Embodiment 1" in the examples and figures) and just miniaturized by making the outer diameter of the diaphragm approximately φ13 or less For a conventional acoustic transducer (hereinafter simply referred to as “conventional product” in the examples and drawings), an artificial ear according to the international standard (IEC) is used, and the earphone is attached to the earphone. The characteristics were measured by inputting a signal of 20 Hz to 20 KHz and 1 mW and converting the emitted signal into an electrical signal with a microphone provided in the artificial ear. The obtained frequency characteristics are shown in FIG. 5, and the total harmonic distortion characteristics are shown in FIG.

As is clear from FIG. 5, the frequency characteristics of the first embodiment are not particularly inferior to those of the conventional product, and both are flat.

Also, as is apparent in FIG. 6, the total harmonic distortion characteristic of the conventional products, it often distorted until midrange from low band is seen, in the first embodiment, good over substantially the entire area total It was found to have harmonic distortion characteristics.

  1: movable iron piece, 2: diaphragm, 3: magnet, 4: coil, 5: pole piece, 6: yoke, 7: edge, 9: resin sheet

Claims (3)

A cylindrical yoke, a diaphragm fixed to the opening surface of one end of the yoke, a movable iron piece fixed on the diaphragm, and a part of the base member provided at the other end of the yoke facing the diaphragm A pole piece projecting in a columnar shape, a coil wound around the columnar portion of the pole piece, and a magnet disposed so as to surround the coil,
An electromagnetic acoustic transducer for an earphone, wherein a diaphragm is fixed to an opening surface of one end of a yoke via a disc-shaped resin sheet whose shape corresponds to the entire shape of an edge at one end of the yoke .   The electromagnetic acoustic transducer for an earphone according to claim 1, wherein an outer diameter of the diaphragm is φ13 or less. The electromagnetic acoustic transducer for an earphone according to claim 1, wherein the resin sheet is thermoformed.

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