JP5084764B2 - Electromagnetic transducer - Google Patents

Description

  The present invention relates to an electromagnetic transducer that reproduces sound from an audio signal by combining a permanent magnet and a diaphragm.

  A conventional electromagnetic transducer is disposed so that a permanent magnet plate and a diaphragm are opposed to each other and covered so as to be sandwiched between members such as a frame, and is attached to, for example, a speaker housing.

The permanent magnet plate has strip-shaped magnet portions (also referred to as a multipolar magnetized pattern) alternately having different polarities at regular intervals. The diaphragm is formed by forming a meandering coil pattern at a position opposite to an interval at a boundary of different polarity of the permanent magnet plate, that is, a so-called magnetized neutral zone. When the current of the audio signal flows through the serpentine coil pattern formed on the diaphragm, the serpentine coil pattern and the multipolar magnetization pattern of the permanent magnet are electromagnetically coupled, and the current is applied to the serpentine coil pattern by Fleming's law. The diaphragm vibrates by acting. Sound waves generated by this vibration are radiated to the outside through sound emission holes drilled in the permanent magnet plate and the frame, and audio reproduction is performed (see, for example, Patent Document 1).
Further, the diaphragm is reinforced with a rigidity imparting member for the purpose of preventing the conductor coil of the meandering coil pattern formed on the diaphragm due to this vibration from being disconnected due to metal fatigue (for example, see Patent Document 2). .

Conventionally, there is a thin speaker called “gummazon type” having a configuration similar to that of the above-described electromagnetic transducer and configured by a long bar-shaped magnet instead of the permanent magnet plate. The Gamson-type thin speaker has a configuration in which the front and back of the diaphragm are sandwiched between bar magnets with alternately arranged bar magnets, and the poles of the bar magnets facing each other across the diaphragm are the same. This member is composed of the same member as the electromagnetic transducer.
Such a thin speaker has a diaphragm formed by attaching copper or aluminum foil to a thin film made of polyester or polyimide and etching a voice coil pattern (see, for example, Non-Patent Document 1). The thin speaker having this configuration also has the same sound wave generation operation for audio reproduction as the electromagnetic transducer.

Japanese Patent No. 3192372 International Publication No. 2003/073787

Edited by Takeo Yamamoto, Speaker System, Radio Technology, July 1977

Since the conventional electromagnetic transducer is configured as described above, after magnetizing the permanent magnets constituting the electromagnetic transducer one by one, the magnets must be assembled alternately with different polarities. There is a problem that the cost is higher than that of a cone type speaker that can magnetize all the magnets by the magnetizing operation. Moreover, the assembly operation of the electromagnetic transducer has to be performed in a state where the permanent magnet is magnetized, and there is a problem that iron powder or the like is mixed during the assembly.
On the other hand, when a permanent magnet plate is disposed only on one surface of the diaphragm in order to obtain an inexpensive speaker, the sound pressure level also decreases because the magnetic flux density near the voice coil on the side without the permanent magnet plate decreases. There was a problem. Moreover, the fluctuation | variation of the magnetic flux distribution which arises in a diaphragm front and back direction becomes large, and the subject that distortion generate | occur | produces occurred.
Furthermore, since the diaphragm base material has a flat thin film structure of several tens of microns, the mechanical strength is small, and natural resonance occurs even at a low frequency. When resonance occurs, there is a problem that abnormal noise due to abnormal vibration of the diaphragm and noise per diaphragm magnet due to increase in amplitude of the diaphragm are generated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a low-cost electromagnetic transducer in which the vibration plate has high rigidity and excellent performance.

The electromagnetic transducer according to the present invention is fixed in a staggered arrangement alternately on a pair of inner wall surfaces of a hollow frame having sound radiation holes on the surface, and opposite to the fixed surface. Concavities and convexities composed of a plurality of permanent magnets having opposite polarities alternately opposed to each other, iron plates fixed to the opposite end surfaces of the staggered permanent magnets, and opposite end surfaces of the staggered permanent magnets Concave and convex shape corresponding to the structure, having a reference plane parallel to the concave and convex portions at the same height as the iron plate at the boundary between the concave and convex portions of the concave and convex shapes, and a meandering coil pattern on the reference plane The vibration plate is formed by forming a concave portion and a convex portion on the basis of the portion where the meandering coil pattern is formed from a planar vibration plate base on which the meandering coil pattern is preliminarily formed. And snake Portions coil pattern is not formed is characterized in that an uneven shape.

  According to the present invention, a plurality of permanent magnets are alternately fixed to the pair of inner wall surfaces of the frame in a staggered arrangement, and opposite end surfaces opposite to each other and having opposite polarities alternately. Thus, after permanent magnets that are not magnetized are attached to the frame and the electromagnetic transducer is assembled, all the permanent magnets can be magnetized together. Moreover, the rigidity of the diaphragm can be increased by providing the diaphragm with a three-dimensional structure having an uneven shape. As a result, it is possible to obtain a low-cost electromagnetic transducer having high vibration plate rigidity and excellent performance.

1 shows a configuration of an electromagnetic transducer according to Embodiment 1 of the present invention, in which FIG. 1 (a) is an external perspective view, and FIG. 1 (b) is an exploded perspective view. It is sectional drawing which cut | disconnected the electromagnetic transducer which concerns on Embodiment 1 of this invention along the AA line shown in FIG. It is the figure which expanded a part of sectional drawing which cut | disconnected the electromagnetic transducer which concerns on Embodiment 1 of this invention along the AA line shown in FIG. 1, and shows a magnetic circuit.

Embodiment 1 FIG.
1A and 1B show a configuration of an electromagnetic transducer 10 according to Embodiment 1 of the present invention. FIG. 1A is an external perspective view, and FIG. 1B is an exploded perspective view. 2 is a cross-sectional view of the electromagnetic transducer 10 cut along the line AA shown in FIG. 1, and FIG. 3 is a partially enlarged cross-sectional view. 1 to 3 are exaggerated and enlarged for simplicity of explanation, and are different from the actual scale.

  The electromagnetic transducer 10 includes an upper frame 16, a permanent magnet 12, an iron plate 18, a diaphragm 11, a permanent magnet 13, and a lower frame 17. The frame formed by superposing the upper frame 16 and the lower frame 17 has a casing structure having a hollow inside. Here, for convenience, they are referred to as an upper frame and a lower frame, but they may be turned upside down.

  On the inner wall surface of the upper frame 16, that is, the surface facing the diaphragm 11, permanent magnets 12 are fixed at a predetermined interval. A plurality of rows of permanent magnets 13 are fixed to a position corresponding to a gap between the permanent magnets 12 on the inner wall surface of the lower frame 17, that is, the surface facing the diaphragm 11. Therefore, as shown in FIG. 2, the permanent magnets 12 and 13 are staggered and fixed to the upper frame 16 and the lower frame 17 alternately.

  As shown in FIG. 2, the permanent magnet 12 fixed to the upper frame 16 has an N pole on the end face fixed to the upper frame 16 and an S pole on the end face facing the diaphragm 11. On the other hand, in the permanent magnet 13 fixed to the lower frame 17, the end face fixed to the lower frame 17 is the S pole, and the end face facing the diaphragm 11 is the N pole. Therefore, the permanent magnets 12 and 13 have a configuration in which end faces facing each other on the side opposite to the fixed face have different polarities.

  Sound radiation holes 15 opened to the outside are provided at regular intervals in portions of the upper frame 16 and the lower frame 17 where the permanent magnets 12 and 13 are not fixed. Further, an iron plate 18 is bonded to the end surfaces of the permanent magnets 12 and 13 facing the diaphragm 11.

  The diaphragm base 11a that is the base of the diaphragm 11 is made of a thermoplastic film such as polyetherimide (PEI), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN). Voice coils 11b made of copper, aluminum foil or the like are formed in a meandering shape on the front and back surfaces of the diaphragm base 11a. Moreover, the diaphragm base 11a is formed with a diaphragm protrusion 11c protruding toward the upper frame 16 and a diaphragm recess 11d protruding toward the lower frame 17 side. A diaphragm reference surface 11f for arranging the voice coil 11b is provided at a boundary portion between the diaphragm convex portion 11c and the diaphragm concave portion 11d. These diaphragm convex part 11c, diaphragm concave part 11d, and diaphragm reference surface 11f have mutually parallel surfaces.

  Further, each of the diaphragm convex portion 11c and the diaphragm concave portion 11d is provided with a diaphragm rib portion 11e having an uneven structure or a rib structure for improving the rigidity of the diaphragm 11. However, since the rigidity of the diaphragm 11 is improved by the uneven shape including the diaphragm convex part 11c and the diaphragm concave part 11d, the diaphragm rib part 11e may not be provided. Further, the diaphragm rib portion 11e may be provided only on a part of the diaphragm convex part 11c and the diaphragm concave part 11d.

  A diaphragm supporting portion 14 is fixed to the outer periphery of the diaphragm 11, and the diaphragm 11 is supported so as to be vertically displaced by fixing the diaphragm supporting member 14 to the inner periphery of the upper frame 16 or the lower frame 17. Is done. As shown in FIG. 2, the diaphragm support member 14 fixes the diaphragm 11 to the frame. At this time, the diaphragm reference surface 11 f on which the voice coil 11 b is arranged is positioned at the same height as the iron plate 18. Aligned.

  Here, a method for forming the diaphragm 11 will be described. First, the voice coil 11b is formed by pasting or etching copper, aluminum foil or the like in a meandering shape on the front and back surfaces of the planar diaphragm base 11a. Then, the diaphragm convex portion 11c and the diaphragm concave portion 11d are formed on the diaphragm base material 11a by hot pressing, vacuum forming, or the like with reference to the attachment location of the voice coil 11b. That is, the reference portion is directly the diaphragm reference surface 11f, and the portions where the voice coil 11b is not attached are the diaphragm convex portion 11c and the diaphragm concave portion 11d. Therefore, although the voice coil 11b and the diaphragm base material 11a having different elongation rates are bonded together, the voice coil 11b and the diaphragm base material 11a can be molded integrally, and the diaphragm base material 11a is not broken. The protruding height of the diaphragm convex portion 11c and the diaphragm concave portion 11d from the diaphragm reference surface 11f is such that the diaphragm 11 supported by the diaphragm support member 14 vibrates and is displaced vertically. 13 is not touching.

  Next, a method for magnetizing the permanent magnets 12 and 13 will be described. First, the permanent magnets 12 are fixed to the upper frame 16 and the permanent magnets 13 are fixed to the lower frame 17 in a staggered arrangement, and the electromagnetic transducer 10 is assembled with the diaphragm 11 interposed therebetween. Thereafter, the assembled electromagnetic transducer 10 is uniformly magnetized in a direction perpendicular to the upper frame 16 and the lower frame 17, whereby the permanent magnets 12 and 13 are magnetized in the same magnetic pole direction. Therefore, the end surfaces of the permanent magnets 12 and 13 facing each other have alternating strip-like polarities.

  Next, the operation principle of the electromagnetic transducer 10 will be described. As shown in FIG. 3, in the vicinity of the voice coil 11 b of the diaphragm 11, the magnetic flux emitted from the N pole of the permanent magnet 13 to which the iron plate 18 is bonded crosses the voice coil 11 b and reaches the S pole of a different permanent magnet 12. When a current (audio signal) is supplied from the outside to the voice coil 11b of the diaphragm 11, the current flowing through the voice coil 11b and the magnetization pattern (magnetic flux density) of the permanent magnets 12 and 13 are electromagnetically coupled to each other. A driving force is generated according to the law. Due to the generated driving force, the vibration plate 11 supported by the vibration plate support portion 14 so as to be displaceable vibrates. This vibration is radiated from the sound radiation hole 15 as audio reproduction sound. Since the iron plate 18 is bonded to one end of the permanent magnets 12 and 13 of the electromagnetic transducer 10, the iron plate 18 forms a magnetic pole and linearly travels from the N pole to the S pole (indicated by an arrow B in FIG. 3). The magnetic flux density is concentrated on. In the present embodiment, since the voice coil 11b is arranged at the height of the arrow B where the magnetic flux density is maximized in the magnetic gap between the permanent magnets, the magnetic flux crossing the voice coil 11b is increased and the sound pressure level is improved. be able to.

As described above, according to the first embodiment, since the diaphragm 11 is formed in the concavo-convex shape by forming the diaphragm convex portion 11c and the diaphragm concave portion 11d, the rigidity is improved and the occurrence of resonance is suppressed. it can. Further, since the diaphragm rib portion 11e is formed in the diaphragm convex portion 11c and / or the diaphragm concave portion 11d, the rigidity can be further improved.
Further, since the voice coil 11b is formed on the diaphragm reference surface 11f, when the diaphragm 11 is three-dimensionally formed into a concavo-convex shape, vibration is generated even though the elongation rates of the diaphragm base 11a and the voice coil 11b are different. The plate base material 11a is not broken and high-precision molding can be realized.

  In addition, since the diaphragm 11 has an uneven shape and the permanent magnets 12 and 13 are arranged in a staggered arrangement so that the magnetic pole direction of the permanent magnet 12 and the magnetic pole direction of the permanent magnet 13 are the same, the electromagnetic transducer 10 After assembling, the permanent magnets 12 and 13 can be magnetized together. Therefore, foreign matters such as iron powder do not enter during assembly work. Therefore, it is possible to prevent an abnormal noise from occurring in the electromagnetic transducer 10 and prevent the initial performance from being lost, and to easily manufacture the electromagnetic transducer 10 having excellent performance.

  Moreover, since the permanent magnets 12 and 13 are arranged in an alternating staggered arrangement, the number of magnets can be halved, and the low-cost electromagnetic transducer 10 can be obtained. Conventionally, if a permanent magnet is arranged only on one side of the diaphragm for the purpose of halving the number of magnets, the magnetic flux distribution fluctuates in the front and back directions of the diaphragm. However, in this embodiment, even if the number of magnets is halved, the diaphragm 11 Since it is arranged in the front and back direction, the magnetic flux distribution in the front and back direction can be made uniform by the front and back magnetic circuits of the diaphragm 11. As a result, the occurrence of distortion can be prevented.

  DESCRIPTION OF SYMBOLS 10 Electromagnetic transducer, 11 Diaphragm, 11a Diaphragm base material, 11b Voice coil, 11c Diaphragm convex part, 11d Diaphragm concave part, 11e Diaphragm rib part, 11f Diaphragm reference plane, 12, 13 Permanent magnet, 14 Vibration Plate support part, 15 sound radiation hole, 16 upper frame, 17 lower frame, 18 iron plate.

Claims (3)

A hollow frame with sound radiation holes on the surface;
A plurality of permanent magnets alternately fixed to a pair of inner wall surfaces of the frame in a staggered arrangement, opposite to the fixed surfaces, and opposite end faces opposite to each other, with different polarities,
An iron plate fixed to the end faces of the permanent magnets facing each other in a staggered arrangement;
It is a concavo-convex shape corresponding to the concavo-convex structure constituted by the end surfaces facing each other of the permanent magnets arranged in a staggered manner, and is a boundary portion between the concave and convex portions of the concavo-convex shape and the same height position as the iron plate A vibration plate having a reference surface parallel to the concave portion and the convex portion, and a meandering coil pattern formed on the reference surface ,
The diaphragm is formed by forming the concave portion and the convex portion of a planar diaphragm base material on which the meandering coil pattern is preliminarily formed on the basis of a portion on which the meandering coil pattern is formed. The electromagnetic transducer, wherein a portion where the coil pattern is not formed has the uneven shape . The recesses and / or protrusions of the diaphragm, an electromagnetic transducer according to claim 1 Symbol mounting, characterized in that the formation of the rib structure or irregular structure for reinforcement. Fixed to a hollow frame provided with sound radiation holes on the surface, a plurality of permanent magnets alternately fixed to a pair of inner wall surfaces of the frame in a staggered manner, and end surfaces facing each other of the permanent magnets arranged in a staggered manner And a concavo-convex shape corresponding to the concavo-convex structure composed of the end faces of the permanent magnets opposed to each other in a staggered manner, and is a boundary portion between the concave and convex portions of the concavo-convex shape, and the iron plate A vibration plate having a reference surface parallel to the concave portion and the convex portion at the same height position, and a meandering coil pattern formed on the reference surface ,
The diaphragm is formed by forming the concave portion and the convex portion of a planar diaphragm base material on which the meandering coil pattern is preliminarily formed on the basis of a portion on which the meandering coil pattern is formed. After assembling the electromagnetic transducer characterized in that the portion where the coil pattern is not formed has the concave and convex shape, it is staggered by magnetizing in a direction perpendicular to the pair of inner wall surfaces of the frame The electromagnetic transducer which makes the said end surfaces which the said permanent magnets mutually faced have different polarities alternately.

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