JPH0227900A - Electrically driven electroacoustic exchange - Google Patents

Abstract

PURPOSE:To obtain a small and high performance speaker by fixing a coil for generating an oscillation force, constructing to move a field magnet and specifying the shaft direction length of a magnetic pole piece to house the coil. CONSTITUTION:A magnetic body having plural magnetic pole pieces 17 and 18 is provided at the fixed side opposite to a field magnet 22 of the cylindrical single pole to magnetize the inner and outer surfaces to a different pole and a coil 24 for generating an oscillation force formed in a ring shape is housed and fixed. Length L in the whole shaft direction of plural magnetic pole pieces 17 and 18 is L>=m+x+alpha, alpha=alphaa+alphab, L>m>x. Here, (m) is the length of the shaft direction of a field magnet, (x) is the length of the oscillation stroke of the field magnet and alphaa and alphab are the lengths to lengthen the magnetic pole piece of the upper and lower edge parts in order to minimize the fluctuation of a magnetic distribution to depend on any of the magnetic flux distribution at the upper and lower edge parts of the shaft direction of the field magnet. Thus, a speaker, which is long line, high in reliability, small and high in performance, can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field of the Invention] The present invention relates to an electrodynamic electroacoustic exchanger (electrodynamic electroacoustic device) such as a speaker, microphone, earphone, etc.
The feature is that the vibration force generating coil is fixed and the field magnet moves, which reduces the weight of the movable body, improving the response speed and suppressing the vibration. Increase the efficiency of converting sound or electric current.

Low-pitched sound can be easily generated, and the υ'-do wire does not need to be dragged, so it can be expected to have a long life.

The structure has been simplified to allow mass production at low cost.

The reason is that it is an efficient electroacoustic exchanger.

[Technical background and problems] Electrodynamic electroacoustic exchanger 1 For example, in a speaker, the voice coil is movably placed in a magnetic field and when a sound current is applied, the voice coil vibrates as the current changes. It is something. In this case, a speaker that reproduces sound waves by moving a vibrating body with a coil is called a dynamic speaker, and a speaker that emits sound waves by directly connecting a coil to a cone-shaped paper or the like is called a dynamic cone speaker. A dynamic horn speaker is one in which a small vibrating body is moved by a voice coil, and a horn (or trumpet) is attached to the front of the vibrating body to efficiently emit sound waves.

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. A similarly cylindrical upper yoke plate 5 is disposed and fixed with an adhesive or the like to form a field section 6, thereby forming a 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.
The peripheral edge of a cone-shaped vibrating body 9 is bonded to the peripheral edge of the frame 7 together with a gasket (satellite) 8 using an adhesive or the like. At the center of the vibrating body 9 is a coil bobbin 1 made of paper, thin plastic, etc., in which a cylindrical voice coil 10 is wound around the lower part of the vibrating body 9.
1 are combined.

The middle part of the coil bobbin 11 holds the voice coil 10 at the center between the magnetic poles and performs appropriate damping (braking) on vibrations.
The voice coil 10 is supported by a damper 12 for applying pressure, so that the voice coil 10 is correctly positioned within the magnetic gap 13 of the field section 6. 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, the voice coil 1
0 drags the lead wire and vibrates, so if used for a long time, the lead wire may break or the solder may come off, leading to damage and shortening the service life. there were.

Further, both terminals of a lead wire (not shown) of the voice coil 10 are pulled out from the top through the magnetic gap 13, and
Since it is guided to the vibrating body 9 (or it may be the frame 7) and soldered at that position, ■ Magnetic gap 1
By using the voice coil 10 with a limited thickness in order to pass both terminals of the lead wire of the voice coil 10 inside the magnetic gap 13, the magnetic flux density within the magnetic gap 13 cannot be increased by the thickness of the lead wire. It was becoming inefficient.

■ 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, the vibrating body 9 is
When the vibrating body 9 is made of the thin film plastic of today, if the terminal of the lead wire is soldered to it, the heat generated at the time will cause holes to form, resulting in a high defect rate. could not be mass-produced. ■
In addition, since both terminals of the lead wire of the voice coil 10 are passed through the magnetic gap 13, there is a risk that the lead wire may come into contact with the fixed side when the voice coil 10 vibrates, so it must be manufactured with great precision. The defect rate was also very high.

In addition, in the case of the conventional speaker 1, since the voice coil 10 vibrates, ■ The conducting wire that makes up the voice coil 10 has a heavy specific gravity (the specific gravity of copper is approximately 7), so the load is large, and the response speed is low. This method has the disadvantage that it is slow and cannot extract audio signals with high precision over a wide range. In particular, it wasn't good enough to extract dynamic bass. ■ Also, in order to eliminate the disadvantage of (■) above due to the very heavy conductor wire for forming the voice coil 10,
In order to prevent the weight of the wire from becoming heavy and to widen the magnetic gap 13 so as not to reduce the magnetic flux density in the magnetic gap 13, the conducting wires are placed closely together so as not to overlap.
The winding must be formed in a densely wound row (or called single row winding).Manufacturing the winding of the voice coil 10, which is tightly wound in one row, requires extremely high precision and is a very difficult process. Therefore, 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, manufacturing the voice coil 10 according to the resistance value is extremely troublesome and has the disadvantage of not being suitable for mass production.

In addition, as described above, the voice coil 10 must be formed by tightly winding it in one row, which makes it impossible to wind the conductive wire in multiple turns, which results in the generation of a large driving force 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 driving force T for vibrating the voice coil 10 is as follows.

T = t - I t: Number of turns in the conductor ■ = given by current, but in the past, due to the above reasons, the number of turns t in the conductor cannot be made to a large value, so a large driving force is required as described above. Not only can you not get
The value of the current (■) also becomes large, which has the drawback of making the speaker 1 inefficient.

[Problem of the Invention] An object of the present invention is to completely change the concept of conventional electrodynamic electroacoustic exchangers and move the field magnet without moving the coil, so that the coil does not drag the lead wire. The objective of this project was to provide an electrodynamic electroacoustic exchanger that would have a long life and high reliability by eliminating damage caused by disconnection of the single lead wire or solder coming off due to vibration.

In particular, in an electrodynamic electroacoustic exchanger that is configured to achieve the above-mentioned problems, a vibrator is used to achieve the problems described later, while also having a compact structure and obtaining a high-performance bass acoustic signal. By ensuring that the field magnets that make up the magnetic field face the magnetic flux generated from the pole piece, a nearly uniform magnetic flux faces the magnetic flux generated from the pole piece, no matter where in the movable stroke the field magnet is located. The objective was to obtain an acoustic signal with good performance by making it possible to obtain a vibration force of .

The object of the present invention is to satisfy the above-mentioned problems, solve the following problems, and increase the magnetic flux density of a field magnet.

And in order to accomplish these tasks.

In order to concentrate the magnetic flux density of the field magnet, the present invention provides magnetic pole pieces that can alternately form N and S poles as shown below. However, the objective was to make effective use of these magnetic pole pieces to effectively house the vibration force generating coil.

That is, a vibration force generating coil storage part is formed of a magnetic material so that the coils can be held, and the coils are separated from each other in the axial direction and have different polarities in the coil storage holding part. By forming a plurality of magnetic pole pieces that can generate a magnetic field, increasing the efficiency of magnetic flux density between the plurality of magnetic pole pieces and the field magnet, and switching the energization to the vibration force generating coil provided in the coil storage holding part, the plurality of magnetic pole pieces can be generated. N on the pole piece of
An actuator that forms magnetic poles such as poles or south poles, generates large attractive and repulsive forces, and generates a large vibration force of the field magnet, and can generate acoustic signals with good vibration response, that is, with high precision. The objective was to make it possible to mass-produce electroacoustic exchangers in a small size and at low cost.

Also, there is no need to pass the lead wire through the magnetic gap between the field magnet and the vibration force generating coil.

Moreover, the problem was to eliminate the troublesome process of soldering both terminals of the lead wire to a vibrating body, etc., to make it excellent in mass production, and to make it possible to manufacture an electrodynamic electroacoustic exchanger at a low cost. It is something that

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.
Moreover, by constructing the field magnet using a magnetic material with a specific gravity smaller than that of the conducting wire forming the coil (for example, one with a specific gravity of 4 to 6), and making it move,
By reducing the weight of the transducer and increasing its response speed, we have made it possible to extract audio signals over a wide range with greater accuracy, and in particular, to be able to construct a device that can extract dynamic bass sounds at a low cost. This was done with the goal of making it possible.

In this way, as a field magnet, a magnetic material with a specific gravity smaller than that of the conducting wire forming the coil (for example, a specific gravity of 4 to 6
The objects of the present invention can be achieved by using an appropriate radially anisotropic rare earth-based or neodymium-iron-boron-based magnet material that can obtain a strong magnetic flux even when constructed using ing.

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 the vibration force generating coil cheaper. The objective of this invention is to make it possible to mass-produce electrodynamic electroacoustic exchangers of a certain quality at a low cost by making it easy to mass-produce them.

In addition, if the purpose is to obtain an extremely large vibration force according to certain specifications, the structure should be such that there is enough space to accommodate a coil wound with many turns. so that it does not have to form,
To extract accurate low-pitched audio signals even in the case of low-pitched sounds by using a coil formed by winding many turns of a conducting wire to generate a large driving force for vibrating the field magnet. This was done with the goal of making it possible to do so.

By doing this, the driving force for vibrating the field magnet T T = t - I t: Number of turns of the conductor ■ = current The number of winding turns t of the conductor is formed to a large value. By this, it is possible to obtain a large driving force T, and by making it possible to reduce the value of the current I, it is possible to obtain an efficient electrodynamic electroacoustic exchanger such as a speaker. It is something that has been done to solve the problem.

[Means for achieving the object of the present invention] The object of the present invention is to provide a cylindrical unipolar field whose inner and outer surfaces are magnetized with different polarities so as to be movable in the axial direction within the cylindrical magnetic gap of a magnetic circuit. A magnetic magnet is provided, and a plurality of magnetic pole pieces that are separated from each other in the axial direction and can form different poles are formed on the fixed side facing the side surface of the field magnet via a radial magnetic gap. A magnetic body having a ring-shaped vibration force generation coil storage recess is provided, and a ring-shaped vibration force generation coil is housed and fixed in the vibration force generation coil storage recess of the magnetic body, and the axis of the field magnet is fixed. In an electrodynamic electroacoustic exchanger in which a vibrating body that interlocks or comes into contact with the field magnet by vibration movement in the direction is attached directly to the field magnet or is provided at intervals, the length m in the axial direction of the entire plurality of magnetic pole pieces. m≧L+X+α α=αa+αb m>L>x, α>αa, αb However, L: Length in the axial direction of the field magnet In order to suppress fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the ends of the

Length to make the magnetic pole piece extra long αa: α: Length to make the magnetic pole piece at the top end longer in order to minimize fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the top end in the direction of the field magnet αb: An electrodynamic electroacoustic exchanger in which the length of the magnetic pole piece at the lower end is set to be longer in order to suppress fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the lower end of the field magnet in the axial direction. This is achieved by providing

[Embodiments of the present invention] [First embodiment of the invention] Fig. 1 shows a dynamic cone speaker 15 of the present invention.
FIG. 2 is a sectional view of the same edge, and FIG. 3 is an explanatory diagram showing the conditions of the field magnet and the magnetic pole pieces. A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

A dynamic cone speaker 15 showing a first embodiment of the present invention is constructed so that the magnetic circuit 16 can be formed very thin in the axial direction, and therefore can be constructed very flat and lightweight. ing.

The magnetic circuit 16 includes a stator 20 made of a magnetic material, in which two ring-shaped magnetic members 17 and 18 made of a magnetic material are stacked one above the other to form a U-shaped section 19 (see FIG. 2) in vertical section. It consists of This stator 20 has an annular magnetic gap 21 (
(see Figure 2) is opposed to the outer peripheral surface of a cylindrical single-pole field magnet 22 whose inner and outer surfaces are magnetized with different polarities so that it can move freely in the axial direction within the radial magnetic gap 21. They are separated from each other at both upper and lower ends in the axial direction so that different poles can be formed on the stator 20 side.
It means "on the surface facing", and also in similar examples below.

In this sense, the expression "separation J" is used.) The magnetic body 17a is made of a high magnetic permeability magnetic body.

18a. The end portions of the magnetic bodies 17a and 18a extending toward the magnetic gap 21 are extended and bent in a direction perpendicular to each other to form a magnetic pole piece 17b.

18b is formed on the stator 20 main body, the vibration force generated by the U-shaped vertical section 19 is generated on the stator 20 side facing the outer peripheral surface of the field magnet 22 via the radial magnetic gap 21. A coil storage recess 23 is formed.

A vibration force generation coil 24 formed in a ring shape is housed and fixed in a vibration force generation coil storage recess 23 formed by the U-shaped portion 19 made of the magnetic material. The lead wire 25 of the vibration force generating coil 24 is led to an external circuit through a through hole 26 formed in the magnetic member 18 forming the U-shaped portion 19. A cylindrical field magnet 2 is connected to the magnetic pole pieces 17b and 18b formed on the stator 20 through a radial magnetic gap 21.
2 is supported within the annular magnetic gap 21 so as to be able to reciprocate in its axial direction.

In order for the field magnet 22 to be able to perform strong and rapid reciprocating vibrations, the field magnet 22 must be formed using an optimal magnet material and an appropriate forming method. Here, the optimum magnet nod material for forming the field magnet 22 is such that the formed field magnet 22 is lighter than the specific gravity of the vibration force generating coil 24 and has a magnetic flux density that is 1 stronger than that of the vibration force generating coil 24. A material that is extremely easy to process or form is desirable. For this reason, the field magnet 22 selected and prototyped by the present inventor has a specific gravity of 1, for example 4, so that a strong magnetic force can be obtained as a magnet throat material, and an extremely thin one can be easily obtained. ~6 rare earths or neodymium, boron, iron (
Using a resin magnet (which may be made of a material other than the above three types of components) (of course, a sintered magnet may be used), the magnet is formed into a cylindrical shape by appropriate means such as injection molding. I am using the one that I made. Field magnet 2
2 is magnetized into a single pole so that the inner and outer peripheries have different polarities, and in this embodiment, the inner periphery is the S pole,
The outer periphery is a single pole magnetized to the north pole.

A cone-shaped frame 27 is fixed to the upper part of the stator 20. The peripheral edge of a cone-shaped vibrating body 28 is coupled to the upper peripheral edge of the frame 27 with a gasket (not shown) using an adhesive or the like. This vibrating body 28
The field magnet 22 is coupled to the lower end cylindrical portion 28a, and is capable of reciprocating vibration in the axial direction within the magnetic gap 21.

A damper 29 is provided between the frame 27 and the cylindrical portion 28a to hold the field magnet 22 at the center of the magnetic pole and apply appropriate damping (braking) to one vibration. Magnetic air 11 of magnetic circuit 16)
321. Further, a dust cap 30 such as a dustproof cloth is attached to the upper surface of the central portion of the vibrating body 28 to prevent dust in the air from entering the magnetic gap 21.

In the supercar 15 having such a structure, an important problem of the present invention is that the field magnet 22 constituting the vibrator has a substantially uniform magnetic flux at any position within its movable stroke. By making it face the magnetic flux generated from the

The purpose is to obtain a high-performance acoustic signal by always obtaining a uniform magnitude of vibration force based on a constant ratio.

Below, a magnetic circuit 16 having a structure capable of achieving the above object will be described with reference to FIG. 3.

In the dynamic cone speaker 15 having the magnetic circuit 16 described above, the length in the axial direction between the magnetic pole pieces 17a and 18a (note that the magnetic pole piece 17b is the length between the magnetic pole pieces 17a and 18a).

18b and the length between the two magnetic pole pieces 17b and 18b), the field magnet Depending on the position of the field magnet 22 in the magnetic gap 21, the field magnet 22 may be vibrated based on a predetermined acoustic signal due to the slope of the magnetic flux distribution at the ends of the field magnet 22 in the vertical axis direction. This greatly affects the vibration force and vibration response of the magnet 22.

As a result, the field magnet 22 can be vibrated with a uniform magnitude based on a fixed ratio regardless of the position within the axial movable stroke within the magnetic gap 21 of the field magnet 22, thereby improving performance. It is desirable to be able to obtain a good acoustic signal.

For this reason, in this speaker 15, as shown in FIG. 3, in the magnetic circuit 16, the axial length of the field magnet 22 and the axial length between the magnetic pole pieces 17a and 18a are
It is formed under the conditions specified below.

Note that the rules of the example shown here can be commonly adopted for other examples, so the rules described in this example are as follows:
This will of course be taken into consideration in other embodiments as needed, so this will not be explained in particular detail in the other embodiments below.

That is, in the speaker 15 described in this embodiment, if the axial length between the magnetic pole pieces 17a and 18a is m, then the axial length m between the magnetic pole pieces 17a and 18a is.

m≧L+X+α α=α ≧+α b m>L>x, a>aa, ab However, L: Length in the axial direction of the field magnet To suppress fluctuations in magnetic distribution due to drooping of magnetic flux distribution at the ends in the axial direction.

Length to make the magnetic pole piece extra long αa: α: Length to make the magnetic pole piece at the top end longer in order to minimize fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the top end in the direction of the field magnet αb = In order to suppress fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the lower end of the field magnet in the axial direction, by setting the length of the magnetic pole piece at the lower end to be longer, the field magnet 22 magnetic air gap 21
The magnetic flux distribution received from the magnetic pole pieces 17a and 18a can be made almost uniform.

As a result, the vibration force obtained by energizing the vibration force generation coil 24 has a substantially uniform magnetic flux distribution in the magnetic gap within the movable stroke of the field magnet 22, and the magnetic flux density is increased. Therefore, since the size is uniform based on a fixed ratio, it is possible to form the speaker 15 that can obtain an acoustic signal with good performance.

[Second embodiment of the invention] FIG. 4 shows a dynamic cone speaker 31 of the invention.
FIG. A second embodiment of the present invention will be described below with reference to FIG. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

A dynamic cone speaker 31 showing a second embodiment of the present invention is different from the speaker 15 of the first embodiment in that it has a fine annular magnetic gap 3 between the inner surface of the field magnet 22 and the radial direction.
A center ball 33 having a cylindrical shape in longitudinal section is provided through the magnetic circuit 2 to almost completely close the magnetic path in the magnetic circuit 34, thereby obtaining a larger vibration force.

The center pole 33 made of a magnetic material is constructed by integrally forming a cylindrical magnetic material perpendicular to the inner circumference of a flat ring-shaped magnetic material 35 fixed to the lower part of the magnetic material 18.

In the speaker 31 of the second embodiment, the center pole 33 is provided on the inner periphery of the field magnet 22 to completely close the magnetic path, so vibration is larger than that of the speaker 15 of the first embodiment. Although force is generated, depending on certain specifications, the sound generated by the speaker 9 may be somewhat distorted, so it is necessary to optimally design the components of the speaker 31 in consideration of specifications, cost, etc. For this purpose, it is convenient to provide a metal body with good conductivity, such as a copper ring, to prevent the generation of eddy currents, for the purpose of reducing inductance, etc., at the location of the center ball 33 facing the field magnet 22. .

Note that the length of the field magnet 22 in the axial direction and the magnetic pole piece 17 are
Regarding the relationship between a and 18a in the axial direction, see the third
Since it is the same as shown in the figure, it will be omitted.

[Third Embodiment of the Invention] Both the speakers 15 and 31 of the first and second embodiments have an outer periphery drive type structure, but in this third embodiment, with reference to FIG. The dynamic cone speaker 36 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.

A dynamic cone speaker 36 showing a third embodiment of the present invention has a magnetic circuit 37 that is very thin in the axial direction and has a small outer diameter and can be formed compactly, and is therefore very flat, small and lightweight. drawing things.

The magnetic circuit 37 includes a field magnet 22 and a magnetic material fixed to a cup-shaped stator 40 made of a non-magnetic material via the inner periphery of the field magnet 22 and a fine radial annular magnetic gap 39. It is mainly formed by the formed ring-shaped magnetic member 38. The ring-shaped magnetic member 38 is formed to have a U-shaped portion 41 in a longitudinal section, and a field is supported on the outer periphery of the U-shaped portion 41 so as to be movable in the axial direction within the annular magnetic gap 39. Magnetic pole pieces 38a, 38 which are separated from each other and can form different poles are provided at both upper and lower ends in the axial direction facing the inner circumferential surface of the magnet 22 via a radial magnetic gap 39.
It forms b. By forming the magnetic pole pieces 38a and 38b, a coil for generating vibration force having a U-shaped longitudinal section is housed in the ring-shaped magnetic body 38 via the inner peripheral surface of the field magnet 22 and the radial magnetic gap 39. A recessed portion 42 is formed. A ring-shaped vibration force generation coil 24 is housed and fixed in the vibration force generation coil storage recess 42 . A lead wire (not shown) of the vibration force generating coil 24 is led to an external circuit through a through hole (not shown) formed in the stator 40 or the like.

Stator 40 is fixed to frame 27 by appropriate means. The stator 40 may be formed integrally with the frame 27. If the stator 40 is made of a magnetic material, the stator 40 may be formed integrally with the frame 27. Side surface 4 of cup-shaped stator 40
0a can also function as a back yoke for closing the magnetic path of the field magnet 22.

Note that the length of the field magnet 22 in the axial direction and the magnetic pole piece 38 are
Regarding the relationship between a and 38b in the axial direction, see the third
Since it is the same as shown in the figure, it will be omitted.

[Action of the invention] In the embodiments of the present invention, the working principle is as follows.

Since they are all the same, I will explain them all together: Speaker 15.
31 and 36, when an alternating current of a magnitude based on the acoustic signal is passed through the vibration force generating coil 24, the two magnetic pole pieces 17a and 18a, 38a and 38b, which are separated from each other in the axial direction, Since the magnetic poles of N pole and SfI are formed so that they are different from each other, the magnetic poles generated in these magnetic pole pieces and the field magnet 22 repeat the attraction/repulsion phenomenon, so that Since a force is generated that causes the field magnet 22 to reciprocate along the axis, the field magnet 22 reciprocates within the magnetic gap 21.42 along its axial direction. - Therefore, the vibrating body 28 fixed to the field magnet 22 vibrates back and forth,
Acoustic signal sounds of appropriate wavelengths and loudness can be generated.

[Effects of the Invention] As is clear from the above configuration, the vibration force generating coil of the present invention has magnetic pole pieces formed on the surface facing the field magnet via a radial cylindrical magnetic gap. It is possible to efficiently collect magnetic flux and increase the magnetic flux density within the magnetic gap.
Moreover, since the two magnetic pole pieces separated from each other in the axial direction form different poles, they can generate a large vibration force and cause the field magnet to reciprocate with good response, allowing for highly sensitive acoustic signals. This has the effect of making it possible to obtain an electrodynamic electroacoustic exchanger that can generate or receive .

Further, in the present invention, by effectively utilizing the above magnetic pole piece, namely,
A vibration force generating coil storage part is formed using a magnetic material,
Since it is possible to hold the vibration force generating coil, there is an effect that the coil can be rationally stored and protected in the vibration force generating coil storage section.

Further, in the present invention, the axial length m of the magnetic pole piece is defined as m≧L+X+α α=α a+α b m>L>x, a>a a, ab, where L: axial length of the field magnet - x: Length of the vibration stroke of the field magnet α: To suppress fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the ends of the field magnet in the axial direction.

Length αa to make the magnetic pole piece extra long: Length αb to make the magnetic pole piece at the top end longer in order to suppress fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the top end in the direction of the mini field magnet. = In order to minimize fluctuations in the magnetic distribution due to drooping of the magnetic flux distribution at the lower end of the field magnet in the axial direction, the length of the magnetic pole piece at the lower end is set to be long, so the field magnet is magnetic. The magnetic flux distribution received from the magnetic pole piece within the air gap can be made almost uniform.

As a result, the vibration force obtained by energizing the vibration force generation coil has a - constant ratio because the magnetic flux distribution generated from the magnetic pole piece of the field magnet is almost uniform and receives a large magnetic flux within the movable stroke. This has the effect of making it possible to obtain an acoustic signal with good performance.

In addition, there is no need to use a voice coil, which is difficult to manufacture and effective as in the past, and because the field magnet moves without moving the coil, there is no need to drag the lead wire and cause it to vibrate. There is no damage caused by cutting or soldering, and a highly reliable and long-life electrodynamic electroacoustic exchanger can be obtained.

Furthermore, since the troublesome process of soldering both terminals of the lead wire of the vibration force generating coil to the vibrating body or the like can be omitted, mass productivity is excellent and manufacturing is possible at low cost.

Furthermore, since the lead wire terminals do not need to be soldered to the vibrating body, the vibrating body can be easily mass-produced at low cost using a desirable thin film plastic. Also, the field magnet (for example, specific gravity 4 to 6) is lighter in specific gravity than the conductor wire (specific gravity 7), and is made of a magnetic material that can strengthen the magnetic force.

This has been difficult in the past because the weight of the vibrator is lighter, the response speed is faster, and audio signals can be extracted over a wider range with higher accuracy. In particular, it has the effect of being able to construct a highly efficient device that can extract dynamic bass acoustic signals at low cost.

Furthermore, there is plenty of storage space for the coil that generates sufficient vibration force, and because the coil does not need to be moved, the troublesome conductor wires that are manufactured in order to form the voice coil can be placed closely together to avoid overlapping. Because it is possible to use flat winding, which eliminates the need to use a dense winding method in which the wire is wound in a single row, it is extremely easy to manufacture the winding of the vibration force generating coil, reducing the defect rate and reducing the number of coils used to generate the vibration force. This has the effect of allowing coils to be mass-produced inexpensively and easily.

Yet again. A field magnet is formed from a magnetic material that can generate strong magnetic force even if it is thin (especially recent technology has made this possible), and a vibration force generating coil such as a ring-shaped coil wound with many turns is used. Therefore, the vibration force generating coil is made by winding a conductive wire with many turns.

By making it possible to generate a large driving force for vibrating the field magnet, there is an effect that an accurate audio signal can be extracted even in the case of a low-pitched audio signal.

Also, if you want to obtain a particularly large vibration force, set the number of turns t of the conductor to a large value, where the driving force to vibrate the field magnet is TT = t - I t: Number of turns of the conductor ■ = current Because it can be done,
Since a large driving force T can be obtained and the value of the current I can also be made small, there is an effect that 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 other electrodynamic electroacoustic exchangers such as microphones having a common structural principle.

4.1! ! ! Brief description of the first aspect FIG. 1 shows a dynamic cone according to the first embodiment of the present invention.
2 is a vertical sectional view of the speaker, FIG. 3 is an explanatory diagram of the relationship between the field magnet and the magnetic pole piece, and FIGS. 4 and 5 are each according to the present invention. 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, 1
2... Damper, 13... Magnetic gap.

14...Dust cap.

15...Dynamic cone speaker.

16... Magnetic circuit, 17... Ring-shaped magnetic member, 1
7a...Magnetic material, 17b...Magnetic pole piece.

18... Ring-shaped magnetic member, 18a... Magnetic body, 1
8b...Magnetic pole piece, 19...U-shaped part.

20... Stator, 21... Annular magnetic gap.

22... Field magnet, 23... Vibration force generation coil housing section, 24... Vibration force generation coil, 25...
・Lead wire, 26...Through hole.

27... Frame, 28... Vibrating body.

28a... Cylindrical part, 29... Damper 30... Dust cap, 31... Dynamic cone speaker, 32... Annular magnetic gap, 33... Center ball, 34... Magnetic circuit , 35...Flat ring-shaped magnetic material.

36...Dynamic cone speaker.

37... Magnetic circuit, 38... Ring-shaped magnetic member, 3
8a, 38b ---Magnetic pole piece.

39... Annular magnetic gap, 40... Stator.

40a...Side surface, 41...U-shaped part.

Claims (1)

[Claims] A cylindrical unipolar field magnet whose inner and outer surfaces are magnetized with different polarities so as to be movable in the axial direction within a cylindrical magnetic gap of a magnetic circuit is provided, and the field magnet A ring-shaped vibration force generating coil storage recess formed with a plurality of magnetic pole pieces that are separated from each other in the axial direction and can form different poles on the fixed side facing the side surface and the radial magnetic gap. A ring-shaped vibration force generation coil is housed and fixed in a vibration force generation coil storage recess of the magnetic body, and the vibration force generation coil is interlocked or applied by the axial vibration movement of the field magnet. In an electrodynamic electroacoustic exchanger in which a vibrating body in contact with the field magnet is provided directly or at intervals, the length m in the axial direction of the entire plurality of magnetic pole pieces
m≧L+X+α α=αa+αb m>L>x, α>αa, αb However, L: Length in the axial direction of the field magnet x: Length of the vibration stroke of the field magnet α: Axial direction of the field magnet Length αa for making the magnetic pole pieces extra long in order to suppress fluctuations in magnetic distribution caused by drooping of magnetic flux distribution at the ends of the field magnet Length αb to lengthen the magnetic pole piece at the upper end in order to minimize fluctuations: In order to minimize fluctuations in magnetic distribution due to drooping of the magnetic flux distribution at the lower end in the axial direction of the field magnet, An electrodynamic electroacoustic exchanger whose length is set to lengthen the pieces.