JPH0227897A - Electrically driven electroacoustic exchange - Google Patents

Abstract

PURPOSE:To obtain a speaker having long life and simple construction by fixing a flat coil for generating an oscillation force to the fixed side of a magnetic circuit and freely reciprocatively oscillatably providing a permanent magnet to magnetize the upper surface and the lower surface to a different pole through the cavity of the shaft direction in the shaft direction. CONSTITUTION:A flat coil 27 for generating an oscillation force such as an air-core type coil is fixed to the fixed side of a magnetic circuit and a permanent magnet 25 formed by the sintering magnet of the shaft direction anisotropy to magnetize the upper surface and the Iower surface to a different pole through a cavity 26 in the shaft direction is provided freely reciprocatively oscillatably in the shaft direction and an oscillator 24 is fitted to the permanent magnet. When the alternating current of the size flows based on the acoustic signal at the coil 27 for generating an oscillation force, the permanent magnet 25 is reciprocated and oscillated along the shaft direction in the magnetic cavity 26, the oscillator 24 is oscillated and an acoustic signal sound is generated. Thus, a speaker is obtained which is high in reliability, long life, small and light-weight.

Description

[Detailed Description of the Invention] [Industrial Application Field of the Invention] The present invention relates to an electrodynamic electroacoustic exchanger for speakers, microphones, earphones, telephones, buzzers, etc. In addition to being thin, compact, and lightweight, the coil is fixed and the permanent magnet moves, which reduces the weight of the movable body, improving response speed and reducing vibration. By increasing the efficiency of converting sound or current, it can easily generate low-pitched sounds, eliminates the need to drag lead wires, promises a long life, and has a simple structure that can be mass-produced at low cost. The reason is that it is an efficient electrodynamic electroacoustic exchanger.

[Technical background and problems] An electrodynamic electroacoustic exchanger 9, for example, a speaker.

When the voice coil is movably placed in a magnetic field and a sound current is passed through it, the voice coil vibrates as the current changes. In this case, a speaker that reproduces sound waves by moving a vibrating body with a coil is called a dynamic speaker. A dynamic cone speaker is a speaker that emits sound waves by directly connecting a coil to a paper cone, etc., and uses a voice coil to move a small vibrating body.

A dynamic horn speaker, for example, is a microphone that has a horn (or trumpet) attached to the front of the speaker to efficiently radiate sound waves.

It has a similar structure to a dynamic speaker, but when a vibrating body moves in response to sound waves, the voice coil attached to it vibrates within a magnetic field and generates an electric current. Since these electrodynamic electroacoustic exchangers all have similar structures, the speaker will be explained below.

Many conventional dynamic cone speakers 1 are constructed as shown in FIG.

That is, a permanent magnet 4 made of a cylindrical ferrite magnet is attached to a yoke plate 3 having a center pole (center magnetic pole) 2. Similarly, a cylindrical upper plate 5 is arranged,
These are fixed with an adhesive or the like to constitute the field section 6, which constitutes the fixed side. The field section 6 shown here is called an external magnet type, but it may also be an internal magnet type that uses a yoke and incorporates a columnar permanent magnet and a center ball in the center of the inside of the yoke. good.

A cone-shaped frame 7 is coupled to this field section 6.
A peripheral edge of a vibrating body 9 formed of cone-shaped paper along with a gas get (satellite) 8 is bonded to the peripheral edge of the frame 7 with an adhesive or the like. At the center of the vibrating body 9 is a coil bobbin 1 made of paper, thin plastic, etc., with a cylindrical voice coil 10 wound around the bottom.
1 are combined. The middle part of this coil bobbin 11 is supported by a damper 12 for holding the voice coil 10 at the center between the magnetic poles and applying appropriate damping (braking) to vibration, and the voice coil 10 is held in the magnetic gap 13 of the field part 6.
I'm trying to position it correctly inside. Further, a dust cap 14 such as a dustproof cloth is attached to the upper surface of the central portion of the vibrating body 9 to prevent dust in the air from entering the annular magnetic gap 13.

According to such a conventional speaker 1, since the magnetic circuit (field part 6) itself must be formed long in the axial direction, it has the disadvantage of being extremely thick, heavy, and large.

Furthermore, according to the speaker 1 having such a configuration, the field part 6 is complicated, a very large permanent magnet 4 is required, which increases the weight, and since the large permanent magnet 4 is exposed, there is a large amount of external leakage. However, it has not been sufficiently developed to be used in various types of audio equipment, etc., which generate magnetic flux and dislike the generation of external leakage magnetic flux.

Further, in the case of the conventional speaker 1, the voice coil 10 drags the lead wire and vibrates, so the lead wire may break depending on the use for a long time.

There is a risk that the solder of the lead wire may come off, leading to damage, and the service life of the lead wire may be shortened.

Further, both terminals of the lead wire of the voice coil 10 are pulled out from the upper part through the magnetic gap 13, and the vibrating body 9 (
or the frame 7) and soldered at that position. ■In order to pass both terminals of the lead wire of the voice coil 10 through the magnetic gap 13, the thickness is limited in the radial direction. By using the blank voice coil 10, the magnetic flux density within the magnetic gap 13 cannot be increased by the thickness of the lead wire, resulting in poor efficiency. Note that the inability to extract dynamic bass sounds is the same with speakers of other structures using piezoelectric elements. ■Since both terminals of the lead wire of the voice coil 10 must be passed through the magnetic gap 13, and both terminals of this lead wire must be soldered to the vibrating body 9, etc., it is not suitable for mass production and is expensive. It had become. ■Also vibrating body 9
If it is made of the thin film plastics of today, if the terminals of the lead wires are soldered to it, the heat generated at that time will cause holes to form, increasing the defective rate, and making it impossible to form the vibrating body 9 with the desired thin film plastics. , could not be mass-produced cheaply.

(2) Also, since both terminals of the lead wire of the voice coil 10 are passed through the magnetic gap 13, the lead wire tends to come into sliding contact with the fixed side when the voice coil 10 vibrates.

For products that must be manufactured with high precision, the defective rate is extremely high.

In addition, in the case of the conventional speaker 1, since the voice coil 10 is vibrated, the specific gravity of the conducting wire that makes up the voice coil 10 (the specific gravity of copper is

7.86) is heavy, resulting in a large load, slow response speed, and disadvantages in that it is not possible to extract audio signals with higher accuracy over a wide range.

In particular, it wasn't good enough to extract dynamic bass. (2) In addition, in order to eliminate the drawback (2) above due to the extremely heavy conductor wire for forming the voice coil 10, in other words, the weight of the voice coil 10 is not increased and the magnetic gap 13 is widened to In order to prevent the magnetic flux density in the air gap 13 from decreasing, the conductive wires must be closely wound in a single row (also called aligned winding) so as not to overlap. Manufacturing the voice coil 10 tightly wound in one row in this way requires great precision and is difficult.
It had the disadvantage of having a high defect rate and being extremely expensive.
(1) One of the causes of the above-mentioned drawbacks (2) and (2) is that in the conventional speaker 1, etc., the resistance value of the voice coil 10 is set as 1, for example, 8Ω by the standard. However, depending on the resistance value, the voice coil 10
It was extremely troublesome to manufacture, and had the disadvantage of not being suitable for mass production.

Furthermore, as mentioned above, the voice coil 10 must be formed by tightly winding it in one row, so it is not possible to form a winding with multiple turns of the conducting wire, and a large vibration force is generated to vibrate the voice coil 10. Therefore, in the case of low-pitched sounds, it was not possible to output audio signals with high accuracy. Also,
In particular, when trying to produce bass sounds with high precision, the precision becomes extremely high.

It has not been possible to produce a speaker or the like that can produce accurate bass sounds at low cost.

Note that the vibration force T for vibrating the voice coil IO is as follows.

T=t-I t: Number of turns in the conductor I: Vibrating force T given by the current is proportional to the number of turns in the conductor and the electric current, but conventionally, for the above reasons, the number of turns t in the conductor is set to a large value. Therefore, not only is it impossible to obtain a large vibration force, but also the value of 4i becomes large, resulting in an inefficient speaker 1.

In addition, in the case of the conventional speaker 1, due to its structure, a dust cap 14 such as a dustproof cloth is attached to the upper surface of the central part of the vibrating body 9 to prevent dust in the air from entering the annular magnetic gap 13. However, it has the drawback of requiring much time and effort, and resulting in an increase in costs.

Furthermore, according to the speaker 1, the field section (magnetic circuit) 6
As is clear from Fig. 6, this method requires the use of a large and heavy permanent magnet 4, which results in a heavy object. had the disadvantage of being expensive.

In addition, since the large permanent magnet 4 is used as described above, the permanent magnet 4 must be exposed and attached, so that a considerable amount of the magnetic flux of the permanent magnet 4 leaks, that is, such a large leakage magnetic flux However, there was a risk that it would have a negative impact on peripheral devices such as various audio equipment, which are becoming increasingly densely packaged.

In addition, since the large permanent magnet 4 must be exposed and mounted as described above, a considerable amount of the magnetic flux of the permanent magnet 4 leaks, resulting in an inefficient speaker 1, which requires the use of a large and heavy permanent magnet. Otherwise, a large amount of expensive permanent magnet material capable of generating a strong magnetic force must be used, which increases the disadvantage that the speaker 1 becomes large, heavy, and expensive.

In addition, in the case of the conventional speaker 1, since the voice coil 10 is of a movable type, the vibrating body 9 made of paper or fiber and the coil bobbin 11 must be integrated. This method has the disadvantage that it is difficult to connect different materials that have not yet been used, and that it is not suitable for mass production.

[Problems of the present invention] The problems of the present invention are to completely change the concept of conventional electrodynamic electroacoustic exchangers, and first, the magnetic circuit (field part) should be a flat coil with an extremely simple and inexpensive structure. The objective was to form an extremely thin magnetic circuit by creating an axial gap type structure using magnets.

To solve these problems, permanent magnets are used as vibrators, but such permanent magnets are expensive and generate strong magnetic force in order to obtain an efficient electrodynamic electroacoustic exchanger with a fast response speed. Even if the exchanger is made of a magnetic material that can be used, its weight can be reduced, and the amount of expensive magnetic material used can be reduced. It is cheaper compared to the price of permanent magnets.

Moreover, the object of this invention was to make it possible to form a speaker with good responsiveness and efficiency at a low cost.

Furthermore, by simplifying the magnetic circuit configuration, it is easy to minimize the leakage magnetic flux of the permanent magnet.

With this configuration, it is possible to prevent external devices from being adversely affected by the leakage magnetic flux of the permanent magnet, and it is also possible to configure the magnetic circuit to be small, making it lighter in weight and suitable for electrodynamic electric devices such as small speakers. The object of this invention was to make it possible to construct an acoustic exchanger inexpensively and easily.

Similarly, by completely changing the concept of conventional electrodynamic electroacoustic exchangers and moving the permanent magnet instead of moving the coil, the coil drags the lead wire and vibrates, causing breakage of the lead wire. The objective of this project was to provide an electrodynamic electroacoustic exchanger that has a long life and is highly reliable, eliminating damage caused by soldering and soldering.

In addition, by placing the coil on the fixed side, the lead wire does not need to pass through the magnetic gap between the coil and the permanent magnet, and the troublesome process of soldering both terminals of the lead wire to the vibrating body etc. is omitted. The goal was to make it mass-producible and to manufacture it at a low cost.

Another problem of the present invention is that by configuring the coil so that it does not move, the lead wire does not come into sliding contact with the fixed side.
By constructing a permanent magnet that is lighter in weight than the voice coil and moving it, the weight of the transducer can be reduced, the response speed can be increased, and audio signals can be transmitted over a wide range with greater precision. The objective of this project was to provide a low-cost device that could extract particularly dynamic bass sounds.

In other words, we used a method that moves permanent magnets.

It is possible to prevent such permanent magnets from being subjected to a large load, and also to generate strong magnetic force, and even if a magnetic material capable of generating such strong magnetic force is used,
The object of the present invention is to provide a permanent magnet that is small in size and light in weight, and therefore can be constructed at low cost.

In addition, by creating a configuration that does not require moving the coil,
The conductor wires, which are very difficult to manufacture, should be placed closely together so that they do not overlap.
By making it possible to use flat winding, which eliminates the need for the close winding method of winding wires in rows (also called aligned winding), it is extremely easy to manufacture a single winding, reducing the defective rate and making it possible to mass-produce the coil at low cost and easily. The goal was to make it possible.

In addition, the coil is formed into a flat, air-core coil shape, which is made by winding many turns of a conductor wire that is extremely inexpensive and easy to wind, and has enough space to accommodate the coil made by winding the conductor wire with many turns. In addition to creating a magnetic circuit structure that allows the permanent magnet to vibrate, the coil does not need to be tightly wound in a single row, but instead uses a flat coil with many turns of conducting wire. The object of this invention is to generate a vibrating force so that accurate audio signals can be extracted even in the case of low-pitched sounds. In doing this, the vibration force T to vibrate the permanent magnet is given by T = t・■ t: Number of turns of the conductor ■: Vibration force T is proportional to the number of turns of the conductor and the current I Therefore, by forming the number of winding turns t of the conductor to a large value, it is possible to obtain a large vibration force T, and by making it possible to reduce the value of the current I, efficiency can be improved. The objective was to provide an electrodynamic electroacoustic exchanger such as a good speaker.

[Means for achieving the object of the present invention] The object of the present invention is to fix a flat vibrating force generating coil such as an air-core coil in which a conductive wire is wound in many turns on the fixed side of a magnetic circuit having an axial gap. , the permanent magnet formed of an axially anisotropic neodymium/iron/boron based sintered magnet whose upper and lower surfaces are magnetized with different polarities through the vibration force generating coil and an axial gap This is achieved by providing a magnetic circuit that can freely reciprocate in the axial direction within the gap thereof, and providing a vibrating body directly or at a distance from the permanent magnet, which is interlocked with or in contact with the axial reciprocating vibration of the permanent magnet. Other issues will be clarified in the explanation below.

[Embodiments of the invention] [First embodiment of the invention] Fig. 1 shows a dynamic cone speaker 16 of the invention.
2 is a longitudinal cross-sectional view of the same, and FIG. 3 is an enlarged perspective view of a stator yoke portion having a peripheral wall. A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

A dynamic cone speaker 16 showing a first embodiment of the present invention has a frame 18 made of a magnetic material 1, for example, a magnetic material having a disc-shaped stator yoke 17 integrally formed in the center by pressing an iron plate. This forms the stator 19. The upper surface of the frame 18 is curved downward in the drawing (see FIG. 2) toward the center. The frame 18 also has four through holes 20 formed on its top surface in order to emit generated sound to the outside. That is, the frame 18 has its outer peripheral portion 18a and the stator yoke 17 connected to each other via a stay 18b.

Further, the stator yoke 17 is formed so as to extend toward the permanent magnet 25 so that the outer circumferential portion of the stator yoke 17, excluding the portion connected to the stay 18b, is located on the outer circumference of the permanent magnet 25, which will be described later. A shaped peripheral wall 17a is formed to close the magnetic path generated from the radial direction of the permanent magnet 25.
It serves as a dust cap to prevent the generation of magnetic flux leakage in the radial direction of the magnetic gap 5, and also to prevent dust in the air from entering into the axial magnetic gap 26, which will be described later. In addition, the frame 18 has its four corners extended downward to integrally form fixing legs 21, and its ends are bent at right angles in the radial outward direction to form through holes 22 for passing fixing screws. A fixing flange 23 is formed. The upper peripheral edge of a cone-shaped vibrating body 24 made of paper, fiber, thin film plastic, or the like is bonded to the upper peripheral edge of the frame 18 with an adhesive or the like together with a gasket (not shown).

The center portion of the lower end of this vibrating body 24 has a thickness of approximately 1 mm or less (
This varies depending on the specifications and size of the speaker 16, but for a small speaker 16, it is recommended to form it to about 0.5 mm).
5 are coupled and disposed so as to be able to reciprocate in the axial direction within the axial magnetic gap 26. The flat permanent magnet 25 is a sintered magnet formed by compression forming of axially anisotropic neodymium/iron/boron system (it goes without saying that components other than the above three types may be included). By using a flat plate made of magnets, it is possible to easily construct a device that fully satisfies the purpose of the present invention. An anisotropic magnet is a magnet with forced spin orientation.

Generally, it can be manufactured by applying a strong magnetic field to the magnetic material before it hardens. Here, the optimum permanent magnet 25 has a size such that the weight of the permanent magnet 25 is lighter than the weight of the flat vibration force generating coil 27 (this coil 27 does not necessarily have to be an air-core type). And 1
It is desirable that a strong magnetic flux density can be obtained. For this reason, in the present invention, the permanent magnet 25 is an axially anisotropic neodymium/iron/boron based sintered magnet that can provide a strong magnetic force as a magnet material and can easily be made extremely thin. This is formed into a flat plate shape by appropriate means such as compression molding. Since the permanent magnet 25 is axially anisotropic, it is magnetized into a single pole so that the upper and lower surfaces have different polarities, and in this embodiment, the upper surface is an S pole. , it is a single-pole type with the lower surface magnetized to the north pole. The permanent magnet 25 has
The permanent magnet 25 is held at a predetermined position in the magnetic gap 26 and supported by a damper to apply appropriate damping (braking) to vibration.
On the inner surface of the stator yoke 17, which faces the upper surface of the permanent magnet 25 with an axial magnetic gap 26 in between, a conducting wire is wound with an appropriate number of turns. A flat air-core type vibration force generation coil 27 is fixed using adhesive, and a lead wire 28 drawn out to the upper end of the vibration force generation coil 27 is guided to its external circuit via a stay 18b. There is. Note that the reference numeral 29 indicates a winding frame made of plastic.

[Second Embodiment of the Invention] FIG. 4 shows a dynamic cone speaker 16 of the present invention.
-1 is an exploded perspective view of the main parts, and FIG. 5 is a longitudinal cross-sectional view of the same. With reference to FIGS. 4 and 5, the second aspect of the present invention will be described below.
An example will be explained. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

The dynamic speaker 16-1 representing the second embodiment of the present invention is the same as the dynamic speaker 16-1 shown in the first embodiment.
This was done to prevent the cone speaker 16 from being damaged due to some kind of external pressure applied from below due to an accident during transportation. be. Yet again. The speaker 16 of the first embodiment has a structure in which a moving yoke is not attached to the lower surface of the permanent magnet 25. This is because if the moving yoke is fixed to the lower surface of the permanent magnet 25, the load on the vibrating body will be heavier due to the weight of the moving yoke, resulting in poor response, making it difficult to meet the specified specifications. This is to avoid being unable to do so.

However, if this continues, the magnetic flux of the permanent magnet 25 will leak to the lower side, creating a problem with poor efficiency. There is a risk that the leakage magnetic flux may have an adverse effect on external devices. Yet again. There is a tendency for the vibrating body 24 to be damaged due to some kind of external pressure applied from the outside during transportation from below.

For this reason, a protective cover plate 31 made of a magnetic material is fixed to the lower part of the speaker 16, and has through holes 30 formed at the four corners that substantially coincide with the through holes 22 described above. in this case,
The protective cover plate 31 may be fixed to the lower part of the flange 23 in advance, or may be fixed using screws (not shown) when fixed to the fixed side of the speaker 16.
The protective cover plate 31 may be temporarily fixed to the lower part of the flange 23 using screws (not shown).

By providing this protective cover plate 31, it is possible to prevent damage to the vibrating body 24 due to the action of the external world from below.
By closing the magnetic path toward the bottom of the permanent magnet 25 and generating a large vibration force, it is possible to obtain a speaker 16-1 with higher efficiency and performance. This has the effect of preventing dust from entering the air.

[Operation of the Invention] In the present invention, the principle of operation is the same, so to explain with reference to the first embodiment, in the speaker 16, an alternating current of a magnitude based on the acoustic signal is applied to the vibration force generating coil 27. When flowing, a force is generated that reciprocates along the axial direction of the magnetic gap 26 according to Fleming's left-hand rule.

The permanent magnet 25 reciprocates within the magnetic gap 26 along its axial direction. Therefore, the vibrating body 24 fixed to the permanent magnet 25 can vibrate to generate an acoustic signal sound having an appropriate wavelength and size.

[Effects of the Invention] Since the present invention has the above configuration, that is, the vibration force generating coil is fixed and the permanent magnet is movable, it is not possible to drag the lead wire as in conventional speakers. Breakage due to sliding contact of the lead wire due to vibration of the voice coil and damage due to solder coming off are eliminated, and a highly reliable and long-life electrodynamic electroacoustic exchanger can be obtained.

Also, unlike the conventional movable voice coil type, it is possible to omit the troublesome process of soldering both terminals of the lead wire to the vibrating body, etc., so it has the advantage of being excellent in mass production and can be manufactured at low cost. Furthermore, because of such a configuration, it is not necessary to solder the terminals of the lead wires to the vibrating body, so that if a desirable thin film plastic is used, the vibrating body can be mass-produced at low cost and easily.

One of the greatest effects sought by the present invention is that in order to reduce the weight of the permanent magnet that serves as the vibrator and obtain a highly responsive one, the present invention employs compression molding to strengthen the magnetic force. directional.

Since it is composed of neodymium, iron, and boron-based sintered magnet materials, the permanent magnet can generate strong magnetic force, and the amount of magnet material used is small, reducing the weight of the vibrator and improving response speed. This has been difficult in the past because it is faster and allows audio signals to be extracted over a wider range with higher precision. In particular, there is an effect that an efficient electrodynamic electroacoustic exchanger that can extract dynamic bass sounds can be constructed at a low cost.

In addition, permanent magnets are small and extremely light in weight, so magnetic circuits can be constructed very easily.

The magnetic path of the permanent magnet can be sufficiently closed.

This has the effect that leakage magnetic flux caused by the permanent magnet does not adversely affect devices external to the speaker.

In addition, permanent magnets can have a magnetic circuit configured to generate only a small amount of leakage magnetic flux, so the cost per duram is higher than that of ferrite magnets. Also, since permanent magnets are very thin, compact, and light in weight, the amount of magnet material that constitutes the permanent magnets used is small, which has the effect of making it possible to form permanent magnets at low cost.

Furthermore, since the magnetic circuit including the permanent magnet can be easily formed, compact and lightweight, there is an effect that the speaker can be formed small and lightweight as a result.

Furthermore, since sufficient space is available and the coil does not need to be moved, it is not necessary to use the close winding method of winding the conductors in a single row to avoid overlapping, which is extremely difficult to manufacture. Since winding can be employed, manufacturing of a single winding is extremely easy, reducing the defective rate and making it possible to mass-produce the coil at low cost and easily.

Yet again. A permanent magnet is formed from a sintered magnet material made of axially anisotropic neodymium, iron, and boron, which can generate strong magnetic force even if it is thin (especially recent technology has made this possible), and is wound with a large number of turns. Since it is possible to use a flat air-core vibrating force generating coil with wires, it is possible to generate a large vibrating force for vibrating the permanent magnet by using the coil formed by winding a conductive wire with many turns. And so on for bass as well.

This has the effect of allowing highly accurate audio signals to be extracted.

That is, the vibration force for vibrating the permanent magnet T T = t ・■ t: Number of turns of the conductor ■ = Lightning current Since the number of turns t of the conductor can be made to a large value,
Since a large vibration force T can be obtained and the value of the current (2) can also be made small, an efficient electrodynamic electroacoustic exchanger such as a speaker can be obtained.

Although the embodiments of the present invention have mainly been described with respect to speakers, the present invention is naturally applicable to electrodynamic electroacoustic exchangers such as microphones that share the same structural principle.

In addition, in the present invention, an example of a speaker in which a permanent magnet and a vibrating body are directly connected has been shown, but the permanent magnet and the vibrating body are arranged at a predetermined interval, and the permanent magnet vibrates. Even if the vibrating body is vibrated directly or indirectly through other members, the principles described above are the same, so it is naturally applicable to these as well.

[Brief explanation of the drawing]

FIG. 1 shows a dynamic cone according to a first embodiment of the present invention.
An exploded perspective view of the main parts of the speaker, Figure 2 is a vertical cross-sectional view of the same,
FIG. 3 is an enlarged perspective view of a stator yoke portion having a peripheral wall, and FIG. 4 is an exploded perspective view of main parts of a second embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of the same, and FIG. 6 is a longitudinal sectional view of a conventional dynamic cone speaker. (Explanation of symbols) 1...Dynamic cone speaker. 2...Center ball (center magnetic pole). 3...Center ball, 4...Permanent magnet. 5... Upper yoke plate, 6... Field section. 7...Frame. 8... Gasket (arrow paper), 9... Vibrating body. 10...Voice coil. 11... Coil bobbin, 12... Damper 13...
magnetic air gap. 14...Dust cap. 15... Lead wire. 16.16-1...Dynamic cone speaker, 17...Stator yoke. 17a...peripheral wall, 18...frame. 18a...outer circumferential portion, 18b...stay 19...stator, 20...through hole. 21...Fixing leg, 22...Through hole. 23...Fixing flange. - Vibrating body, 25...Permanent magnet. - Axial magnetic gap. - Coil for generating vibration force.・Lead wire, 29... winding frame.・Through hole 231・°・・Protective cover plate.

Claims (1)

[Claims] A flat vibration force generating coil such as an air-core coil formed by winding a number of turns of a conducting wire is fixed on the fixed side of a magnetic circuit having an axial gap, and the vibration force generating coil is connected to the vibration force generating coil through the axial gap. A permanent magnet formed of an axially anisotropic neodymium/iron/boron sintered magnet whose upper and lower surfaces are magnetized with different polarities is installed to freely reciprocate in the axial direction within the gap of the magnetic circuit. An electrodynamic electroacoustic exchanger, comprising: a vibrating body that interlocks with or comes into contact with the permanent magnet by reciprocating axial vibration of the permanent magnet, either directly or at a distance from the permanent magnet;