JPS609398B2 - electroacoustic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrodynamic electroacoustic transducers for use in loudspeakers, earphones or microphones.

More particularly, the present invention relates to an electroacoustic transducer having a vibrating membrane having an electrical conductor and placed in a permanent magnetic field. This type of converter is disclosed in U.S. Patent No. 3,013,905.
No. 3,164,686. The advantage of this type of transducer is that the membrane can be easily fabricated to vibrate with uniform phase over its complete movable surface. However, known transducers of this type have a construction that makes them relatively expensive to manufacture and also have the disadvantage that they cannot easily provide the high impedances that are particularly desirable in the case of microphones and earphones. The main object of the present invention is to provide an electroacoustic transducer in which the entire vibratable portion of the flexible membrane vibrates uniformly and in phase, thereby causing no distortion in the generated sound or electrical signals.

Another object of the present invention is to provide an electroacoustic transducer which has a simple magnet, is simple in construction, easy to assemble and handle, and also facilitates the manufacture of a portable membrane.

Still another object of the present invention is to provide an electroacoustic transducer in which the length of the conductor can be made arbitrary. According to the invention, a permanent magnet having one magnetization surface;
An electrodynamic electroacoustic transducer is provided comprising a vibrating membrane parallel to and facing this plane and a continuous flexible conductor carried by the membrane.

The magnetized surface of the permanent magnet has a north pole and a south pole, one of which forms a closed loop around the other. A transient wall of the magnetized plane separates the poles and the magnetic field formed between the poles traverses this wall. The membrane is disposed in the magnetic field and the electrical conductors on the membrane are arranged such that the field lines of the magnetic field cross the membrane at approximately right angles in the portion of the membrane opposite the transition surface. Furthermore, in the portion of the membrane the electrical conductor has a plurality of helices so that each field line of the magnetic field bridging the transient surface traverses the electrical conductor multiple times. In a preferred embodiment, the magnet is a plate of magnetically anisotropic material;
It is magnetically oriented with a direction of magnetization generally parallel to the plane facing the membrane, so that the magnetic field resides primarily in that plane and only slightly in the opposite plane.

In this way, a strong magnetic field can be obtained. More powerfully surrounding the electrical conductor if two similar permanent magnets are used and the magnets are placed on opposite sides of a membrane having poles of the same polarity collinear with each other across said membrane. Moreover, a uniform magnetic field can be obtained.

Next, the present invention will be explained in more detail with reference to the accompanying drawings.

1 to 4 show an electroacoustic transducer 10 used in earphones. The sound generating element is generally a flat circular membrane 11.
The membrane is held along the periphery between two IJ rings 12 held in place in annular housing 13 by retaining clips 14. Membrane 11 is made of polyester film approximately 0.01 mm thick and has annular waves 15 concentric with the periphery and is very flexible. An aluminum foil with a thickness of about 0.01 rib is pasted on one side of this film. A continuous electrical conductor 16 is formed from this foil, which electrical conductor forms a number of helices forming a current path between a peripheral portion 17 and a central portion 18 of the foil. A pair of flat annular permanent magnet plates are attached to a housing 13 provided on opposite sides of the membrane 11 and equally spaced apart.

The opposing surfaces 21 of the plates 20 are mutually concentric and parallel to each other and parallel to the membrane 11, with the membrane 1 disposed between them.
1 forms a gap 22 in which the particles 1 can vibrate. The central part of the membrane 11 and the central part of the plate 20 are fastened together by a bolt 23 and a nut 24. Bolts on ring 12 and flange spacers 25, 26 maintain membrane 11 and plate 20 in position. Each plate 20 is provided with a number of holes 27.

The walls of each hole form an exponential 1 horn with an axis directed away from plane 21 and parallel to the rat of plate 20. The plates 2 are magnetized so that each of the opposing surfaces 21 has three poles: a circular north pole at the center, a circular south pole between the center and the periphery, and a circular north pole along the periphery.

Therefore, each plate consists of two annular plates with a normal S pole.
Forms a permanent magnetic field. The magnetization is shown diagrammatically in FIGS. 3 and 4, where the holes 27 have been omitted for the sake of clarity. From these figures, it can be seen that the direction of magnetization is radial and the magnetic field mainly exists on the surface 21 and only a small amount exists on the opposing surface. In FIG. 4, the magnetic poles are indicated by concentric annular castles labeled N and S and separated by annular regions labeled 28 (hereinafter referred to as transitional castles).

This representation is for illustration only and in reality the poles and transient planes are not clearly separated as shown in FIG. 4, but are gradually integrated. Therefore, the annular castles N and S indicate only the centers of the poles, and the annular castle 28 indicates the region where the magnetic field is strong. Since both plates are magnetized in exactly the same way, the troughs and transient surfaces of both plates are identical. Plate 20 may be formed from any suitable magnetic material, but is preferably a high coercivity magnetically anisotropic material, such as a plastic bonded barium ferrite or cobalt rare earth magnetic material (sold by General Electric Company under the trade name GECOR). ) is formed from.

In the illustrated embodiment, the plate is formed from the plastic-bonded barium ferrite described above, known as Fenoxdure, and prior to magnetization of the plate, the barium ferrite is oriented radially and generally parallel to the preferred direction of magnetization, i.e., opposite surface 21. Arranged in In conclusion, the magnetic field exists mainly on the opposing surface 21 and a small amount on the opposite surface. As shown in FIG. 2, electrical conductor 16 forms a continuous current path between peripheral portion 17 and central portion 18. As shown in FIG.

In particular, the electrical conductor has a number of spirals 3 around the central portion 18.
form 0. In the drawing, only a few helices are shown, but in reality there are many helices, for example, several hundred. Therefore, the width of the conductor is on the order of 0.1 rib and the spacing between the helices is on the order of 0.01 skin. The direction of the helix is reversed approximately at the center between the periphery and the center, so that the current flowing through the conductor is relative to the point opposite the south pole of the magnetic plate 20, i.e., the point where the magnetic field in the air gap 22 changes direction. The direction of the flow is reversed at the point where the flow occurs.

Therefore, it occupies two identical ring-shaped castles in Rasen 3 River Membrane 11. That is, one is an outer castle facing the outer transition surface region 28 of the magnetic plate 20, and one is an inner castle facing the inner transition surface region. Electrical conductor 16 is electrically coupled to the two terminal sections.

One is formed by the ears 31 attached to the peripheral foil section 17 and the other is formed by the bolts 23 and collar 25 electrically connecting the central foil section 18.

Via these terminals the transducer is coupled, for example, to an output circuit of an audio amplifier. The general mode of operation of the transducer shown in FIGS. 1-4 is similar to that of known transducers of the same type.

However, by arranging the conductor in many helices, the conductor can maintain the currently required high impedance for a long time. Furthermore, as a result of the three-pole magnetization of the magnetic plates and the reversal of the direction of the helix, the effects of external magnetic fields are eliminated and the conductor operates as a double turn. 5-7, converter 10A is shown.

Membrane 11A has electrical conductors 16A on both sides thereof and peripheral portion 1
It is fixed only in 7A. Although the membrane is not shown with corrugations, the membrane may be provided with annular corrugations. Furthermore, as shown in FIG. 7, the two permanent magnetic plates 20A have four annular poles of alternating polarity. Although holes are not shown, the magnetic plate is preferably configured to allow sound to pass through. In FIG. 6, the arrangement of conductors on one side of the membrane is the same as on both sides of membrane 11A.

In this figure, the electrical conductor is shown as a single helical line between the peripheral and central foil portions 17 and 18 for simplicity. Since there are three transition surfaces 28A on the opposing surfaces of the magnetic plate, the helical body 30A reverses its direction twice. The two portions of conductor on either side of the membrane are electrically coupled to each other at the center of the membrane, designated 32 in FIG. The peripheral foil portion 17A is electrically coupled to a pair of terminal ears 31A. In the illustrated embodiment, the film and permanent magnetic plate are circular, but these members may be square, rectangular,
Needless to say, it may be oval or any other suitable shape.

In this case, the shape of the helical body is naturally formed to match the shape of the poles and the transitional wall. Also, although most of the best results are obtained when the permanent magnetic plate has a relatively large number of poles, even two poles may provide sufficient performance. In this case, only one transition surface and all helical bodies oriented in one direction are constructed. As described above, the present invention provides a "pair of perforated permanent magnet plates with N and S poles magnetized in a concentric ring shape, which are provided so that the same poles face each other with a movable membrane interposed therebetween, A plurality of conductors are arranged in a helical shape at the portion facing the transition surface of the permanent magnet plate, and a flexible film is fixed to the permanent magnet plate at the central and peripheral parts. The flexible membrane is electrically connected to the fixing member that fixes it to the permanent magnet plate, and the terminal ears on the surrounding city side are electrically connected, and the fixing member and the terminal ears are used as terminal parts. The entire vibrating part vibrates uniformly and in phase, so that there is no distortion in the generated sound or electrical signal.

In addition, the N and S poles are formed concentrically on the facing surfaces of each permanent magnet so that the two poles face each other, and the magnetic flux connecting the N and S poles exists on the air gap side to create a permanent flexible antinode. Since it is placed between the magnets, the magnetic flux applied to the conductor is strong, and since the permanent magnet is polarized, the N and S poles need only be magnetized to the same zero, making the magnet simple and inexpensive. The conductor has a helical shape at the point where it faces the permanent magnet's transient surface, so the length of the conductor can be arbitrarily selected. The conductor is fixed to a magnetic plate, and the central part of the conductor is electrically coupled to a fixing part that fixes the flexible film to the permanent magnet plate, and the peripheral part is electrically coupled to a terminal lug. Since the fixing member and the terminal ears are used as terminal members, the structure is simple, and not only is assembly and handling easy for the customer, but also the flexible membrane can be manufactured easily. Embodiments of the present invention are listed below.

1. The electroacoustic transducer according to the claims, wherein one side of the magnet extends along a J-closed loop around one pole and has an additional magnetic pole having the same polarity as the other pole; an additional transitional surface area separating one pole and an additional pole, and the electrical conductor has a plurality of helical shapes in a vibratable membrane portion facing the additional transitional surface area, and
Electroacoustic transducer, characterized in that the direction of the additional helix is reversed with respect to the direction of the helix.

2. The electroacoustic transducer according to the claims, wherein one side of the magnet has a plurality of additional magnetic poles extending into two closed loops around one pole, and the additional magnetic poles are connected to each other and to each other. a plurality of transitional surface areas separated from one pole, the poles adjacent to said one surface having opposite gutter characteristics, and said electrical conductor having a plurality of vibrating membrane portions in each 2 of the vibrating membrane portions facing the transitional surface area; 1. An electroacoustic transducer having a helical body in which the direction of the helical body in any of the membrane parts is reversed with respect to the direction of the helical body on an adjacent part.

3. The electroacoustic transducer according to claim 1 or 2, wherein one surface of the magnet is circular, and the pole and transition surface area are annular and have the same D as the one surface. electroacoustic transducer. 4. 3 above, characterized in that the vibrating membrane portion has a circular wave of the same D as the one surface.
The electroacoustic transducer described in Section 1.

5. The electroacoustic transducer according to claim 1 or 2 to 5, wherein the center portion of the membrane is fixed to a magnet.

6. The above-mentioned device, characterized in that one end of the converter is electrically coupled to a terminal member at the center of the one surface, and the other end of the conductor is electrically mated to the terminal member at the periphery of the one surface. The electroacoustic transducer according to item 5.

7 Electric conductors are placed on both sides of the membrane, and the part of the conductor placed on one side is electrically coupled to the part placed on the other side only at the center of the waist. An electroacoustic transducer according to the claims and claims 1 to 6 above.

8. The magnet is a plate made of magnetically anisotropic material and is magnetically arranged in the direction of magnetization parallel to the one surface, so that the magnetic field exists mainly on the one surface and only slightly on the other surface. An electroacoustic transducer according to the claims and items 1 to 7 above.

9. The above-mentioned claims and 1 above, characterized in that the magnet has a large number of holes, and the wall of the magnet is formed with an exponential social horn having an axis extending in the lateral direction of the one surface. The electroacoustic transducer according to item 8.

10 A second permanent magnet having an N pole, an S pole, and a transition area separating the poles on one surface, and the N pole, the S pole, and the transition area separating the poles are each aligned with the N pole. said two magnets are arranged on opposite sides of the membrane with the poles and transitional surface of one magnet facing and coinciding with the poles and transitional surface of the other magnet. The electroacoustic transducer according to the claims and items 1 to 9 above.

11. Electroacoustic transducer as shown in the accompanying drawings and described in the specification.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view in all directions of the electroacoustic transducer of the present invention used in an earphone, FIG. 2 is a cross-sectional view taken along the row n line in FIG. 1, and FIG. 4 is a sectional view taken along the line W-W in FIG. 3, FIG. 5 is a sectional view in the axial direction of another embodiment, and FIG.
FIG. 7 is a plan view corresponding to FIG. 2 of the film of the example shown in the figure, and FIG. 7 is a plan view corresponding to FIG. 4 of one magnetization plane of the magnet of the example shown in FIG. . In the figure, reference numeral 1 is an electroacoustic transducer, 11 is a membrane, 13 is a housing, 15 is an annular wave, 16 is a conductor, 2 is a magnetic plate,
22 is a void, and 27 is a hole. FIG. 1FIG. 2 FIG. 3 FIG-< FIG. 5 FIG. 6 FIG. 7

Claims (1)

[Claims] 1. A pair of flat perforated permanent magnet plates that are spaced apart from each other and have opposing surfaces facing each other with an air gap, and a pair of flat perforated permanent magnet plates that are made of a non-magnetic and non-conductive material and that are made of a non-magnetic and non-conductive material. a flexible membrane having an outer circumferential portion held between outer circumferential portions and a vibrating portion located in a gap between opposing surfaces of the permanent magnet plates, the opposing surfaces of the permanent magnet plates comprising: It has a plurality of annular poles separated by an annular transitional surface area concentrically in a state where adjacent poles have different polarities, and each pole of one permanent magnet plate and the transitional area are separated by each of the other permanent magnet plate. The poles and the transition surface area are individually faced to each other through the air gap, and the poles of the same polarity are faced to each other through the air gap, interconnecting each pole of the permanent magnet plate, and the transition surface area. the permanent magnet plates are magnetized such that lines of magnetic force bridging the regions are substantially present on the opposing surfaces; the vibrating portion of the flexible membrane is provided with a continuous electrical conductor; a plurality of helical-shaped transitional surface areas extending from the central part of the flexible membrane facing the pole located at and across the vibrating part facing the transitional surface area of the permanent magnet plate, the helical directions being adjacent to each other; The flexible membrane is fixed to the permanent magnet plate at the center and the periphery so that the entire portion between the center and the periphery can vibrate, and the flexible membrane is inverted between the center and the periphery. is electrically coupled to a fixing member that fixes the flexible membrane to the permanent magnet plate on the central side, and is electrically coupled to the terminal ear on the peripheral side, and the fixing member and the terminal ear are electrically coupled to each other on the peripheral side. An electroacoustic transducer characterized in that it uses as a terminal member.