JP2004015574A - Electroacoustic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroacoustic transducer for obtaining a sufficient characteristic even when it is shared with a receiver and a speaker. <P>SOLUTION: In a yoke 2 fixed to a frame 1, a cylindrical part 2a is integrally formed on a disk shape bottom board, and the half cross section of the yoke has a substantially projected shape. A ring shape first magnet 3 is joined to the outer peripheral part of the yoke 2, and a disk shape second magnet 4 is joined to the center part. A first top plate 5 is joined onto the upper surface of the first magnet 3, and a second top plate 6 is joined onto the upper surface of the second magnet 4. The first magnet 3 forms a first magnetic circuit passing a route: first top plate 5→a first magnetic gap g1→the cylindrical part 2a→the first magnet 3. The second magnet 4 forms a second magnetic circuit passing a route: the second top plate 6→a second magnetic gap g2→the cylindrical part 2a→the second magnet 4. First and second coils 8, 9 are adhered and fixed to the lower surface of a diaphragm 7, and the winding wire terminals 8a, 9a are joined by soldering 12 with terminal patterns 11a on the lower surface after passing the side surface of the frame 1. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electroacoustic transducer used for a speaker or a receiver of a mobile phone or the like.
[0002]
[Prior art]
2. Description of the Related Art In recent years, electroacoustic transducers for mobile communication devices such as mobile phones include those for receivers that are used by pressing them against the ears and those for speakers that are used away from the ears. In the case of a mobile phone, there are cases where a single electro-acoustic transducer is used to fulfill these two functions, and cases where a dedicated electro-acoustic transducer is used separately. In each case, a thin and high-performance speaker or receiver is required. An example of such a conventional electroacoustic transducer will be described with reference to the drawings. FIG. 3B is a bottom view of the conventional electrodynamic loudspeaker, and FIG. 3A is a sectional view taken along line BB of FIG. 3B.
[0003]
First, the configuration of the speaker will be described. In FIG. 3, reference numeral 51 denotes an annular case of a resin molded product, which has an inner peripheral step 51a and an intermediate step 51b. Reference numeral 52 denotes a pot-shaped yoke made of a magnetic material embedded in the inner periphery of the case 51. Numeral 53 denotes a disk-shaped permanent magnet fixed to the center of the inner surface of the yoke 52 and magnetized in the vertical direction. Numeral 54 denotes a disk-shaped top plate fixed to the upper surface of the permanent magnet 53. The permanent magnet 53 forms a magnetic circuit through a magnetic gap that is a gap between the upper end of the yoke 52 and the outer periphery of the top plate 54.
[0004]
Reference numeral 55 denotes a substantially spherical diaphragm integrally formed of a plastic material having a flat portion 55a near the periphery and a curved portion following the flat portion 55a. Adhesively fixed. Reference numeral 56 denotes a voice coil which is a cylindrical air-core coil formed by winding a coil winding of an enamel-coated copper wire in a rectangular cross section and solidifying it with paint, and the upper surface thereof is bonded to the lower surface of a flat portion 55a of the diaphragm 55. Fixed. The voice coil 56 is fitted into the magnetic gap to a depth approximately half the coil length. Reference numeral 57 denotes a protector made of light metal or the like for protecting the diaphragm 55, and a peripheral portion is fixed on the diaphragm 55 of the intermediate step portion 51b of the frame 51. Each of the frame 1 and the protector 57 is provided with a plurality of sound emission holes.
[0005]
Reference numeral 58 denotes a substrate made of glass-containing epoxy resin or the like provided on the lower surface of the case 51, and is provided with a pair of V-shaped terminal patterns 58a. Reference numeral 59 denotes solder that joins the winding terminal 56a of the voice coil 56 guided through a groove provided on the side surface of the frame 51 along the lower surface of the diaphragm 55 to one branch of the terminal pattern 58a. . The other branch serves as a connection terminal when this speaker is incorporated in a device.
[0006]
When an audio signal is applied to the voice coil 56 of the speaker, the voice coil 56 is driven by interaction with a magnetic circuit according to Fleming's left-hand rule, and the diaphragm 55 vibrates up and down to emit sound.
[0007]
Conventionally, there was a special speaker for mania who fixed a plurality of voice coils to one diaphragm and used a plurality of magnets to reproduce a complex vibration mode. Nothing switched the signal. Also, Japanese Patent Application Laid-Open No. H11-252683 discloses a magnetic circuit provided with two diaphragms with voice coils for one magnetic circuit.
[0008]
[Problems to be solved by the invention]
However, since the conventional speaker having such a configuration uses one diaphragm and one voice coil, when shared with the receiver and the speaker, the required characteristics are different. Either one of the properties must be emphasized, or both properties must be compromised, and sufficient properties cannot be obtained in any case. That is, if the characteristics of the receiver (resonance frequency 300 to 500 Hz) are emphasized, a thin diaphragm (thickness of about 10 μm) is used. Then an abnormal sound is generated. In this case, in order to prevent an abnormal sound from occurring, it is necessary to cut a signal in a band below a certain frequency in a circuit manner. Further, when a speaker (resonant frequency of 600 to 800 Hz is the mainstream) is emphasized, since the resonant frequency is relatively high, it does not conform to the receiver standard, so that it is necessary to perform circuit correction. In addition, when a structure using two diaphragms is used, it is difficult to make the electroacoustic transducer thin.
[0009]
The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide an electroacoustic transducer which can obtain sufficient characteristics even when used as a receiver and a speaker.
[0010]
[Means for Solving the Problems]
Means of the present invention for achieving the above object is to form a magnetic circuit with a permanent magnet, a yoke fixed to one magnetic pole of the magnet, and a top plate fixed to the other magnetic pole, and In the electro-acoustic transducer configured to drive the diaphragm by interaction with a voice coil fixed to a plate, a first coil is disposed outside the one diaphragm as the voice coil, and a second coil is disposed inside the diaphragm. It is characterized in that the coil is fixed and a pair of terminal patterns is provided to which each winding terminal of the two coils is connected, so that a signal current can be selectively applied to the two coils.
[0011]
The half section of the yoke has a substantially convex shape, and the permanent magnet has a ring-shaped first magnet joined to the outside of the projection of the yoke, and a disk-shaped second magnet joined to the center of the yoke. A first top plate having an annular shape on the first magnet, and a second top plate having a disc shape on the second magnet, and on the outside of the convex portion of the yoke. The first coil faces the formed first magnetic gap, and the second coil faces the second magnetic gap formed inside the protrusion of the yoke.
[0012]
Further, a half cross section of the yoke has a substantially concave shape, and an outer first half formed between the yoke and an annular top plate joined on a ring-shaped magnet provided in a concave groove of the yoke. The first coil and the second coil face the one magnetic gap and the inner second magnetic gap, respectively.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a bottom view of the electro-acoustic transducer according to the first embodiment of the present invention, and FIG. 1A is a cross-sectional view showing an A-A cross section of FIG. FIG. 2 is a sectional view of an electroacoustic transducer according to a second embodiment of the present invention.
[0014]
First, a configuration of an electroacoustic transducer according to an embodiment of the present invention will be described. In FIG. 1, reference numeral 1 denotes a frame which is an annular resin molded product, and a yoke described later is embedded in a center hole. A step 1a is formed on the outer periphery of the frame 1, and a plurality of sound emission holes are formed inside the step 1a. Numeral 2 is a yoke of a magnetic material embedded in the frame 1, which is formed integrally with a cylindrical portion 2a serving as a convex portion on a circular bottom plate and has a substantially convex half-section (half of the cross-section passing through the center). Has formed. Reference numeral 3 denotes a first magnet, which is a ring-shaped permanent magnet magnetized in the vertical direction, and is joined to the yoke 2 outside the cylindrical portion 2a. Reference numeral 4 denotes a second magnet, which is a disk-shaped permanent magnet magnetized in the vertical direction, and is joined to the center of the yoke 2.
[0015]
Reference numeral 5 denotes a first top plate of an annular magnetic body adhered to the upper surface of the first magnet 3, and reference numeral 6 denotes a second top plate of a disk-shaped magnetic body joined to the upper surface of the second magnet 4. The first magnet 3 causes the first top plate 5 → the cylindrical portion 2a → the bottom surface of the yoke 2 → the first magnetic circuit passing to the first magnet 3; and the second magnet 4 causes the second top plate 6 → the cylindrical portion 2a → the yoke. A second magnetic circuit passing from the second bottom surface to the second magnet 4 is formed. A first magnetic gap g1 and a second magnetic gap g2 are formed between the cylindrical portion 2a and the first top plate 5, and between the cylindrical portion 2a and the second top plate 6.
[0016]
Reference numeral 7 denotes a diaphragm of a resin molded product whose outer peripheral edge is adhered and fixed to the step portion 1a of the frame 1, and annular planar portions 7a and 7b are formed at positions of the first magnetic gap g1 and the second magnetic gap g2. ing. Reference numerals 8 and 9 denote a first coil and a second coil of a voice coil, which is a cylindrical air-core coil in which coil windings, which are enamel-coated copper wires, are wound in a rectangular cross section and solidified with paint. The first coil 8 is fixed to the lower surface of the flat portion 7a, and the second coil 9 is bonded and fixed to the lower surface of the flat portion 7b.
[0017]
The winding ends 8a and 9a of the first coil 8 and the second coil 9 are respectively directed from the upper ends of the first coil 8 and the second coil 9 to the outer periphery of the frame 1 along the lower surface and the upper surface of the diaphragm 7. Have been withdrawn. Reference numeral 10 denotes a protector made of light metal or the like having a sound emission hole for preventing the diaphragm 7 adhered and fixed to the diaphragm 7 of the step portion 1a of the frame 1 to prevent damage. Reference numeral 11 denotes two pairs of fan-shaped substrates on which the terminal patterns 11a are formed. The winding terminals 8a and 9a of the first coil 8 and the second coil 9 are guided to the lower surface of the frame 1 through the grooves on the side surface of the frame 1, and are fixed on the pair of terminal patterns 11a by solder 12 respectively.
[0018]
Next, the operation and effect of the embodiment of the present invention will be described. This electro-acoustic transducer is provided with two voice coils and terminal patterns corresponding thereto. For a receiver or a sound such as hands-free, a signal current is applied to the terminal pattern 11a of the inner second coil 9. For a speaker such as a melody, a signal current is applied to the terminal pattern 11 of the outer first coil 8 or both voice coils of the first coil 8 and the second coil 9. By selectively driving the two coils in this way, in the case of a receiver, the area of the diaphragm 7 outside the second coil 9 can be increased, so that the rigidity of the diaphragm is reduced and the resonance frequency is reduced. Can be lowered. On the other hand, in the case of a speaker for a melody or the like, the outer first coil 8 having a large voice coil diameter can be used, and the sound pressure increases. This is because the driving force F applied to the diaphragm 7 is proportional to the effective wire length L of the coil (driving force F = magnetic force B / effective coil length L / current I). Therefore, even if one electroacoustic transducer is shared, it is possible to exhibit sufficiently satisfactory characteristics in each application by selectively driving two coils.
[0019]
Generally, receivers of φ10 mm (voice coil diameter: about φ5 mm) in Japan and φ13 mm (voice coil diameter: about φ6.5 mm) overseas are the mainstream, so that the performance of the currently used receiver and speaker alone is impaired. The characteristics can be ensured without the need. Further, in the present structure, the resonance frequency can be lowered without using a thin diaphragm, so that the thickness of the diaphragm emphasizing the loudspeaker can be selected, so that an abnormal sound in a low frequency range can be avoided.
[0020]
Next, a second embodiment of the present invention will be described. FIG. 2 is a cross-sectional view of an electroacoustic transducer according to a second embodiment of the present invention. The bottom view is the same as that of the first embodiment shown in FIG. In FIG. 2, the electroacoustic transducer of the first embodiment differs from the electroacoustic transducer only in the configuration of the magnetic circuit unit. Therefore, the same components are denoted by the same reference numerals and names, and the details are omitted. Only the following will be described.
[0021]
Reference numeral 12 denotes a yoke, which has a disk shape having a ring-shaped concave groove between the central portion 12a and the outer wall portion 12b. That is, the half cross section is substantially concave. Reference numeral 14 denotes a ring-shaped permanent magnet joined to the center of the groove. Reference numeral 16 denotes an annular top plate joined on the magnet 14. The upper surfaces of the top plate 16 and the yoke 12 are substantially at the same height, and a first magnetic gap g1 and a second magnetic gap g2 are formed between the top plate 16 and the outer wall portion 12b and the central portion 12a of the yoke 12, respectively. ing. The first magnetic circuit passing through the top plate 16 → the first magnetic gap g1 → the outer wall 12b → the magnet 14 by one magnet 14, and the top plate 16 → the second magnetic gap g2 → the center 12a → the first magnetic circuit passing through the magnet 14. Two magnetic circuits are formed. The first coil 8 and the second coil 9 are arranged in the two magnetic gaps g1 and g2, respectively.
[0022]
Next, the operation and effect of the second embodiment will be described. Two voice coils, a first coil 8 and a second coil 9, are fixed to one diaphragm 7, and each winding terminal is connected to an independent terminal pattern. The diaphragm 7 can be vibrated in different modes by selectively passing a signal current through the coil or both coils. Since only one magnet and one top plate are used, the number of parts is small and the cost can be reduced. In addition, the same effects as those obtained in the first embodiment can be obtained.
[0023]
【The invention's effect】
As described above, according to the present invention, a permanent magnet, a yoke fixed to one magnetic pole side of the permanent magnet, a top plate fixed to the other magnetic pole side, a frame in which the yoke is embedded, In an electroacoustic transducer comprising a diaphragm fixed to a frame and a voice coil fixed to the diaphragm, two voice coils are fixed to one diaphragm, and a winding terminal of the voice coil Are connected to terminal patterns provided independently of each other, so that the two voice coils can be selectively driven. Therefore, even if one electroacoustic transducer is shared for a receiver or a speaker, In such applications, sufficiently good characteristics can be exhibited.
[Brief description of the drawings]
FIG. 1A is a sectional view of an electroacoustic transducer according to a first embodiment of the present invention, and FIG.
FIG. 2 is a cross-sectional view of an electroacoustic transducer according to a second embodiment of the present invention.
3A is a cross-sectional view and FIG. 3B is a bottom view showing a conventional electroacoustic transducer.
[Explanation of symbols]
1 Frame 2 Yoke 2a Cylindrical part (convex part)
3 First magnet 4 Second magnet 5 First top plate 6 Second top plate 7 Vibration plate 8 First coil 9 Second coil 8a, 9a Winding terminal 11a Terminal pattern g1 First gap g2 Second magnetic gap 12a Central part 12b Outer wall part 14 Magnet 16 Top plate

Claims (3)

A permanent magnet, a yoke fixed to one magnetic pole of the magnet, and a top plate fixed to the other magnetic pole form a magnetic circuit, and the interaction between the magnetic circuit and a voice coil fixed to the diaphragm causes the vibration. In the electro-acoustic transducer configured to drive a plate, a first coil is fixed to the outside of one of the diaphragms as the voice coil and a second coil is fixed to the inside of the diaphragm, and each of the windings of the two coils is fixed. An electro-acoustic transducer comprising a pair of terminal patterns connected to wire terminals, wherein a signal current can be selectively applied to both coils. A half cross section of the yoke has a substantially convex shape, and the permanent magnet has a ring-shaped first magnet joined to the outside of the projection of the yoke, and a disk-shaped second magnet joined to the center of the yoke. An annular first top plate is joined on the first magnet, and a disc-shaped second top plate is joined on the second magnet, and is formed outside the convex portion of the yoke. 2. The electric device according to claim 1, wherein the first coil faces the first magnetic gap, and the second coil faces a second magnetic gap formed inside the convex portion of the yoke. Sound transducer. A half cross section of the yoke has a substantially concave shape, and an outer first magnetic member formed between the yoke and an annular top plate joined on a ring-shaped magnet provided in the groove of the yoke. The electroacoustic transducer according to claim 1, wherein the first coil and the second coil face the gap and the inner second magnetic gap, respectively.

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