JP2006352573A - Electromagnetic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic transducer which suppresses abnormal noise by preventing air leak from the inside and improves deterioration of sound pressure of an audio signal even in a low band. <P>SOLUTION: The electromagnetic transducer 10 has the following (1)-(6), (1) a bottom permanent magnetic board 11 on which a multipolar magnetization pattern is formed, (2) an oscillation film 15 arranged opposite to the bottom permanent magnetic board 11 via a buffering material 13, (3) a top permanent magnetic board 17 arranged opposite to the oscillation film 15 via the buffering member 13, (4) a frame 30 which covers structure 20 by overlapping (1)-(3), (5) an input terminal 35 attached to the bottom of a rear frame 31 and electrically connected with the structure 20 and (6) a first sealing material 40a which covers outer surroundings of a boundary line A between the rear frame 31 and the input terminal 35 and a second sealing material 40b which covers one end which does not project in a caulking part 35b of the input terminal 35. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electromagnetic transducer for reproducing an audio signal, for example.

  Various technologies have been proposed for electromagnetic transducers combining a permanent magnet and a vibrating membrane. This type of electromagnetic transducer normally includes a permanent magnet plate, a vibration film disposed so as to face the permanent magnet plate, and a buffer member disposed between the permanent magnet plate and the vibration film. Yes. The permanent magnet plate is formed by alternately forming different strip-shaped magnetic poles at regular intervals (hereinafter, this parallel striped magnetized pattern is also referred to as a multipolar magnetized pattern). Further, the vibration film is arranged to face the formation surface of the multipolar magnetization pattern, and is composed of a meandering conductor pattern at a position facing a so-called neutral zone of magnetization between the different magnetic poles. A coil is formed on the entire surface. A plurality of sound radiation holes for emitting the generated sound wave to the outside are formed at a constant pitch in the gap portion between the magnetic strips having different belt-like shapes on the permanent magnet plate described above (Patent Document 1).

  The structure in which the above-described permanent magnet plate, vibration film, and buffer member are stacked includes, for example, a plate-like back frame that is laid on the lower side of the above-described structure, and a front frame that covers the upper side and the periphery of the above-described structure. It is covered with a frame constructed by bonding. In addition, an input terminal electrically connected to the above-described structure is provided on the lower side of the above-described plate-like back frame that is the back surface of the electromagnetic transducer. The electromagnetic transducer configured as described above is attached to a housing for an audio device such as a speaker, and is used as an audio device for reproducing an audio signal.

JP-A-9-331596

Since the conventional electromagnetic transducer is configured as described above, there is a slight gap between the frame and the input terminal installed on the lower side. Therefore, the sound wave (air) generated from the inside of the electromagnetic transducer leaks to the outside from the gap portion described above, causing abnormal noise in the electromagnetic transducer or reducing the sound pressure. Such a decrease in the sound pressure is more noticeable because the straightness of the sound wave is lower as the frequency is lower (in this case, the band is 200 Hz or lower).
In addition, when an acoustic device is configured and operated by attaching an electromagnetic transducer to a speaker housing or the like, it is affected by sound waves due to vibration amplitude in the speaker portion of the acoustic device. The decrease is more noticeable. This is because the air (sound wave) leaked to the outside due to the air leak described above interferes with and cancels out the sound wave emitted from the original sound radiation hole, thereby reducing the sound pressure.
Therefore, there has been a problem that it is unavoidable that abnormal noise occurs in the electromagnetic transducer or that the sound pressure decreases.

  The present invention has been made to solve the above-described problems, and prevents air leakage from the inside of the electromagnetic transducer to suppress abnormal noise, thereby improving the decrease in sound pressure of an audio signal even in a low band. It is an object to obtain an electromagnetic transducer capable of operating. Another object of the present invention is to obtain an electromagnetic transducer capable of maintaining the original sound pressure level by suppressing the generation of abnormal noise and the decrease in sound pressure even when an acoustic device is configured using the electromagnetic transducer. .

The electromagnetic transducer according to the present invention includes the following 1) to 6).
1) A permanent magnet plate in which different belt-shaped magnetic poles are alternately formed at regular intervals.
2) A vibration film in which a coil made of a meandering conductor pattern is formed on the entire surface at a position facing a permanent magnet plate and facing a gap between different magnetic poles of the permanent magnet plate.
3) A buffer member disposed between the permanent magnet plate and the diaphragm.
4) A frame that covers the structure in which the above 1) to 3) are stacked.
5) An input terminal attached to the frame and electrically connected to the above structure.
6) A first sealing material that covers the outer periphery of the boundary between the frame and the input terminal.

According to the present invention, the frame includes a frame that covers the structure in which the permanent magnet plate, the vibration film, and the buffer member are overlapped, and the first sealing material that covers the periphery of the boundary between the input terminal attached to the frame. Thus, the electromagnetic transducer is configured to prevent sound waves (air) generated from the inside of the electromagnetic transducer from leaking to the outside through the gap between the aforementioned boundaries. For this reason, there is an effect that an electromagnetic transducer capable of suppressing abnormal noise and suppressing a decrease in sound pressure even in a low band can be obtained.
Further, even when an acoustic device is configured using an electromagnetic transducer, an electromagnetic transducer capable of improving the sound pressure drop of the audio signal of the electromagnetic transducer and maintaining the original sound pressure level is obtained. There is an effect that it is.

Hereinafter, various embodiments of the present invention will be described.
Embodiment 1 FIG.
FIG. 1 is an exploded perspective view for illustrating the configuration of an electromagnetic transducer according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view of the electromagnetic transducer according to Embodiment 1 of the present invention, which is cut away at a portion including a sound radiation hole. Note that hatching indicating a cross section is partially omitted.
Here, one diaphragm is sandwiched from above and below by two permanent magnet plates via a buffer member. Further, here, a permanent magnet plate in which a sound radiation hole for radiating sound waves to the outside is referred to as an upper permanent magnet plate, and a permanent magnet plate facing the upper permanent magnet plate through a vibration film is For convenience, this will be referred to as a side permanent magnet plate.

  In the figure, the lower permanent magnet plate 11 has alternating strip-shaped magnetic poles (N poles, S poles) made of sintered ferrite magnets at regular intervals on almost the entire surface facing a vibration film 13 described later. (Hereinafter, this parallel striped magnetized pattern is also referred to as a multipolar magnetized pattern). A so-called neutral zone nz exists in the gap between different magnetic poles (N pole, S pole).

A vibration film 15 is disposed via a buffer member 13 at a position on the upper side of the lower permanent magnet plate 11 that faces the surface on which the multipolar magnetization pattern is formed. The vibration film 15 is formed by forming a coil (hereinafter also referred to as a meandering coil pattern) 15b made of a meandering conductor pattern on the entire surface of a thin and flexible resin film 15a. Each of the linear portions in the longitudinal direction of the meandering coil pattern 15b is provided at a position corresponding to the neutral zone nz in the gap portion between different magnetic poles (N pole, S pole) of the lower permanent magnet plate 11. Yes. Here, the straight portion refers to a long straight portion of the coil 15b that is arranged in parallel to each other with a certain interval.
On the upper side of the vibration film 15, an upper permanent magnet plate 17 in which a band-like multipolar magnetization pattern made of sintered ferrite magnets is formed on almost the entire surface facing the vibration film 15 with the buffer member 13 interposed therebetween. Has been. The upper permanent magnet plate 17 is provided with sound radiation holes 17a at a constant pitch along a neutral zone nz of a gap between magnetic poles (N poles and S poles) having different multipole magnetization patterns.

A plate-like back frame 31 on which the structure 20 is placed below the structure 20 in which the lower permanent magnet plate 11, the buffer member 13, the vibration plate 15, and the upper permanent magnet plate 17 are stacked; The frame 30 is configured by bonding together the front frame 33 that covers the upper side and the periphery of the structure 20. A sound radiating hole 33a is provided corresponding to the position where the sound radiating hole 17a is formed in the portion of the frame 30 that covers the upper side of the structure 20 in the front frame 33.
An input terminal 35 is electrically connected to the structure 20 and provided below the back frame 31. Specifically, the input terminal 35 is fixed by caulking and fixing a caulking portion 35b provided at the center thereof and auxiliary tools 35c on both sides of the caulking portion 35b to the back frame 31. The caulking portion 35 b has a hollow column shape (here, a quadrangular column shape), and one end 35 d that protrudes is connected to the back frame 31. The other non-projecting end 35 e is open on the side opposite to the frame 30.
A slight gap exists at the boundary A between the back frame 31 and the input terminal 35 of the frame 30. The first sealing material 40a is provided so as to cover the outer periphery of the boundary A between the back frame 31 and the input terminal 35 so as to close the gap of the boundary A. Further, one end 35e of the caulking portion 35b that does not protrude is also covered with the second sealing material 40b.

  Here, as the first and second sealing materials 40a and 40b, tape-shaped foamed resin materials were used. The foamed resin material is a material that can obtain excellent airtightness by being compressed. Since it can be bent freely, it can be attached in conformity with the frame shape and is suitable as a sealing material. Further, the tape-like foamed resin material used here is one in which a double-sided adhesive tape is attached to one side, and the workability is good.

Next, the operation will be described.
When a signal is input from the input terminal 35 and a current as an audio signal flows through the meandering coil pattern 15b formed on the surface of the vibration film 15, the meandering coil pattern 15b and the lower side disposed opposite to the meandering coil pattern 15b The multi-pole magnetized patterns on the upper permanent magnet plates 11 and 17 are electromagnetically coupled, and the vibration film 15 vibrates in the thickness direction according to Fleming's left-hand rule. And 33a are emitted into the air.
At this time, the first sealing material 40 a prevents sound waves (air) due to vibration generated from the inside of the electromagnetic transducer 10 from leaking outside through the gap between the back frame 31 and the input terminal 35 in the frame 30. Similarly, the second sealing material 40b prevents sound waves (air) similarly generated from the inside of the electromagnetic transducer 10 from leaking to the outside through one end 35e of the caulking portion 35b that does not protrude.

  As described above, according to the electromagnetic transducer 10 of Embodiment 1 of the present invention, the first sealing material 40a covering the outer periphery of the boundary portion between the back frame 31 and the input terminal 35 in the frame 30 is provided. Therefore, the sound wave (air) generated from the inside of the electromagnetic transducer 10 is prevented from leaking outside through the gap at the boundary A. For this reason, generation | occurrence | production of abnormal noise can be suppressed in the electromagnetic transducer 10, and it can prevent that the sound pressure of an audio signal falls also in a low zone | band. Moreover, even when an acoustic device is configured by attaching an electromagnetic transducer to a speaker housing or the like, it is possible to prevent a decrease in sound pressure and to maintain the original sound pressure level of the electromagnetic transducer.

  Further, since the second sealing material 40b is provided so as to cover the non-projecting one end 35e of the caulking portion 35b in the input terminal 35, the air from the inside of the electromagnetic transducer 10 is received in the same manner as the first sealing material 40a. The caulking portion 35b is prevented from leaking to the outside through one end 35e that does not protrude. For this reason, generation | occurrence | production of unusual sound can be suppressed in the electromagnetic transducer 10, and it can prevent more effectively that the sound pressure of an audio signal falls also in a low band. In addition, even when the acoustic device is configured by attaching the electromagnetic transducer 10 to a speaker housing or the like, the sound pressure can be more effectively prevented from decreasing and the original sound pressure level of the electromagnetic transducer can be maintained. it can.

  In the first embodiment, as the first sealing material 40a and the second sealing material 40b, an example in which a tape-like foamed resin material is used has been shown. However, even if a foamed resin material without a double-sided tape is used, both sides are used. By applying an industrial adhesive instead of the tape, a sealing material having the same function can be obtained. Further, the material is not limited to the foamed resin material, and may be, for example, silicone rubber. Silicone rubber is liquid and has an advantage that it can be easily hermetically sealed even in fine gaps. In addition, the material is not limited to these materials as long as the functions as the first and second sealing materials are satisfied and the same effect is obtained.

1 is an exploded perspective view showing a configuration of an electromagnetic transducer according to Embodiment 1. FIG. 2 is a cross-sectional view showing a configuration of an electromagnetic transducer according to Embodiment 1. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Electromagnetic transducer, 11 Lower permanent magnet plate, 13 Buffer member, 15 Diaphragm, 15a Resin film, 15b Coil which consists of a meandering conductor pattern, 17 Upper permanent magnet plate, 17a Sound radiation hole, 20 Structure, 30 Frame, 31 Back frame, 33 Front frame, 33a Sound radiation hole, 35 input terminal, 35a Input terminal plate, 35b Caulking part, 35c Auxiliary tool, 35d Projected end, 35e Projected end, 40a First sealing material, 40b Second sealing material, nz neutral zone, A Boundary between the rear frame and the input terminal.

Claims (6)

1) a permanent magnet plate in which different belt-shaped magnetic poles are alternately formed at regular intervals;
2) A vibrating membrane in which a coil made of a meandering conductor pattern is formed on the entire surface at a position facing the permanent magnet plate and facing a gap between the different magnetic poles of the permanent magnet plate;
3) a buffer member disposed between the permanent magnet plate and the vibrating membrane;
4) a frame that covers the structure in which the above 1) to 3) are stacked;
5) an input terminal attached to the frame and electrically connected to the structure;
6) An electromagnetic transducer comprising a first sealing material that covers the periphery of the boundary between the frame and the input terminal.   2. The electromagnetic transducer according to claim 1, wherein the first sealing material is a foamed resin material.   2. The electromagnetic transducer according to claim 1, wherein the first sealing material is silicone rubber.   The input terminal includes an input terminal plate and a caulking portion that is a hollow column provided through the input terminal plate, and the caulking portion has one protruding end connected to the frame, and the other end. The electromagnetic transducer according to claim 1, wherein one end of the protrusion is provided with a second sealing material covering the one end.   The electromagnetic transducer according to claim 4, wherein the second sealing material is a foamed resin material. The electromagnetic transducer according to claim 4, wherein the second sealing material is silicone rubber.

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