JP2010124094A - Electromagnetic converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic converter for suppressing the generation of noise by the divided vibrations of a vibrating film. <P>SOLUTION: The electromagnetic converter includes: the vibrating film 20 which is disposed facing a plurality of permanent magnets 10 arranged in parallel, has a conductor coil 20b composed of a conductor coil pattern in a meandering shape and formed at a position facing the gap part of the different magnetic poles of the permanent magnets, and is provided with a plurality of cuts 22; a thin film sheet 21 braided in the vibrating film through the cuts provided on the vibrating film; and a frame 30 for holding the permanent magnet, the vibrating film and the thin film sheet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electromagnetic transducer that is provided with a conductor pattern on the surfaces of a permanent magnet and a diaphragm and reproduces sound from an audio signal.

Some rectangular electromagnetic transducers using a permanent magnet plate and a vibrating membrane include a permanent magnet plate and a vibrating membrane arranged opposite to each other, and a cushioning material arranged between the permanent magnet plate and the vibrating membrane. These permanent magnet plate, vibration film, and buffer member are covered with a member such as a frame and attached to, for example, a speaker housing.
The permanent magnet plate has a belt-like magnetized portion where the polarities are alternately changed at regular intervals. The vibrating membrane is a meander-shaped conductor that acts as an electromagnetic coil facing a portion of the gap between the magnetized portions of the permanent magnet plate, which is alternately magnetized, so-called magnetized neutral zone. A pattern is provided.
When an audio signal current flows through a conductor pattern formed on the diaphragm, the conductor pattern acting as an electromagnetic coil and the permanent magnet plate are electromagnetically coupled, and the diaphragm having the conductor pattern vibrates according to Fleming's law. The sound wave generated by this vibration is radiated through a permanent magnet plate and a sound emitting hole confined in the frame, and audio reproduction is performed (see, for example, Patent Document 1).
In addition, an electromagnetic transducer having a configuration similar to that of the above-described electromagnetic transducer has already existed, and there is an ultra-thin speaker called a “gummazone type”. The permanent magnet plate is a rod-shaped permanent magnet, and the other members can be the same. The rod-shaped permanent magnet has a configuration in which the same poles face each other (N pole and N pole or S pole and S pole), and the poles are alternately arranged in the arrangement direction perpendicular to the bars (for example, see Non-Patent Document 1). . According to this configuration, the sound generation operation for audio reproduction is the same as described above.

Japanese Patent No. 3192372 Supervised by Tamon Saeki, Encyclopedia of Speakers and Enclosures, Seibundo Shinkosha, May 1999

In any of the above-described electromagnetic transducers, the vibrating membrane is a so-called full-surface electroacoustic transducer in which a driving force due to the conductor pattern is uniformly generated on the vibration surface. In other words, the vibrating membrane becomes a piston sound source, and an electromagnetic transducer exhibiting flat sound pressure frequency characteristics can be realized. However, in reality, it is difficult for the diaphragm to vibrate with the piston by generating a uniform driving force over the entire band, and in particular, as the aspect ratio of the diaphragm is increased, the diaphragm tends to generate divided vibrations. .
FIG. 3 is a cross-sectional view showing the divided vibration in the conventional electromagnetic transducer 100. FIG. 3A is a cross-sectional view showing a vibration state when the divided vibration of the vibrating membrane 120 has a ½ wavelength, and FIG. 3B shows the case where the divided vibration of the vibrating membrane 120 has one wavelength. It is sectional drawing which shows the vibration state of.
As shown in FIG. 3, in the conventional electromagnetic transducer 100, as the aspect ratio of the vibrating membrane 120 increases, the vibrating membrane 120 easily splits, and the vibrating membrane 120 becomes a permanent magnet plate due to a partial large amplitude. There was a problem that an abnormal noise was generated upon hitting 110. In addition, there is a problem that sound pressure frequency characteristics are disturbed by the divided vibration of the vibration film 120 and the sound pressure is deteriorated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electromagnetic transducer that suppresses divided vibrations of a diaphragm and has a flat sound pressure frequency characteristic.

  In the electromagnetic transducer according to the present invention, a conductor coil composed of a meandering conductor coil pattern is disposed at a position opposed to a plurality of permanent magnets arranged in parallel and facing a gap portion between different magnetic poles of the permanent magnet. A vibration film formed and provided with a plurality of cuts, a thin film sheet knitted into the vibration film through the cuts provided in the vibration film, and a frame for holding the permanent magnet, the vibration film and the thin film sheet Is.

  According to the present invention, since the thin film sheet knitted into the vibration film through the cut provided in the vibration film is provided, the divided vibration of the vibration film can be suppressed, and the sound pressure frequency characteristic is made flat and stable. Can be made. In addition, since no weight is added to the diaphragm itself, the influence on driving of the diaphragm can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of an electromagnetic transducer 1 according to Embodiment 1 of the present invention. FIG. 1A is a cross-sectional view showing the configuration of the electromagnetic transducer 1 at a braided position of the thin film sheet 21, and FIG. 1B is an upper magnetic circuit (the upper permanent magnet 11 and the upper frame 31) of the electromagnetic transducer 1. It is the top view which showed the vibrating membrane 20 surface when removing ()).
FIG. 2 is a cross-sectional view of the side surface in the longitudinal direction of the electromagnetic transducer 1 for illustrating the operating state of the electromagnetic transducer 1 according to Embodiment 1 of the present invention.

  As shown in FIG. 1A, the electromagnetic transducer 1 includes a permanent magnet 10, a vibration film 20, a thin film sheet 21, and a frame 30. The permanent magnet 10 includes a plurality of upper permanent magnets 11 and a plurality of lower permanent magnets 12, and the frame 30 includes an upper frame 31 and a lower frame 32.

  Each of the plurality of upper permanent magnets 11 and the plurality of lower permanent magnets 12 is a rod-shaped permanent magnet magnetized on both sides by two poles, and is parallel and vibrated at a certain interval as shown in FIG. The surfaces facing the membrane 20 are arranged so that the polarities thereof are alternately different, and are bonded and fixed to the upper frame 31 and the lower frame 32 with an adhesive or the like.

  The vibration film 20 includes a base material 20a made of a rectangular thin polymer resin sheet, and a conductor coil 20b formed in a meandering conductor coil pattern on both surfaces of the base material 20a. The conductor coil 20b made of a meandering conductor coil pattern is formed by pressing or etching a metal foil. The conductor coil 20 b formed on the vibration film 20 is formed at a position facing the gap between different magnetic poles of the permanent magnet 20.

  In addition, the vibration film 20 is provided with a cut line 22 for weaving a thin film sheet 21 arranged so as to divide the longitudinal direction of the vibration film 20. As shown in FIG. 1, the cuts 22 are formed along the longitudinal direction of the vibration film 20 at a predetermined interval in the short direction of the vibration film 20.

  The thin film sheet 21 is formed of, for example, a polymer resin having the same heat resistance as that of the base material 20a of the vibration film 20. Further, the thin film sheet 21 is formed longer than the width of the vibration film 20 in the short direction, and is configured to freely vibrate the vibration film 20 up to a certain amplitude and to suppress vibrations beyond that. The thin film sheet 21 is knitted through slits 22 formed in the diaphragm 20 at predetermined intervals, thereby dividing the longitudinal direction of the diaphragm 20. Both ends in the longitudinal direction of the thin film sheet 21 protruding from both sides in the short direction of the vibration film 20 are sandwiched and supported by the frame 30. In the first embodiment of the present invention, the vibration film 20 is divided by four thin film sheets 21 as shown in FIG.

  The frame 30 has a housing structure in which a cavity is formed inside by combining an upper frame 31 made of a metal such as iron and a lower frame 32. The permanent magnet 10 and the thin film sheet 21 are formed in the formed cavity. The knitted diaphragm 20 is stored. Although not shown, the frame 30 is provided with an input terminal for supplying a drive current for the audio signal.

  As shown in FIG. 1A, the upper frame 31 and the lower frame 32 are formed with sound emission holes 31a and 32a for emitting sound waves to the outside when the diaphragm 20 vibrates. The sound emitting holes 31a and 32a are formed at positions corresponding to substantially the middle portions between the different magnetic poles of the plurality of upper permanent magnets 11 and the plurality of lower permanent magnets 12, respectively. It is provided at predetermined intervals along the longitudinal direction of the magnet 12.

Next, the operation of the electromagnetic transducer 1 configured as described above will be described.
The plurality of upper permanent magnets 11 and the upper frame 31 form an upper magnetic circuit, and the plurality of lower permanent magnets 12 and the lower frame 32 form a lower magnetic circuit. When the drive current of the audio signal flows through the conductor coil pattern 20b formed on both surfaces of the vibration film 20 disposed in the formed magnetic circuit, the vibration film 20 vibrates in the vertical direction according to Fleming's left-hand rule. Sound waves generated by the vibration of the vibrating membrane 20 in the vertical direction are emitted from the sound emitting holes 31 a and 32 a formed in the upper frame 31 and the lower frame 32.

Here, since the vibration film 20 is divided so as to be knitted by the thin film sheet 21 and supported by the frame 30, audio vibrations can be generated with a plurality of amplitudes in which the large amplitude of the vibration film 20 is suppressed. In the electromagnetic transducer 1 according to the first embodiment of the present invention, four thin film sheets are assumed as shown in FIG. 2 assuming that the vibrating membrane 20 does not contact the permanent magnet 10 when the vibrating membrane 20 is a divided vibration of 3/2 wavelength or more. 21 is divided. As described above, the diaphragm 20 is divided into a plurality of amplitudes that do not contact the permanent magnet 10, so that no abnormal noise is generated, and the sound pressure frequency characteristic becomes flat and stable.
Furthermore, since the thin film sheet 21 is knitted by the cuts 22 provided in the vibration film 20, the weight of the thin film sheet 21 is not added to the vibration film 20 itself, and the influence on driving of the vibration film 20 can be reduced. it can.

  As described above, according to the electromagnetic transducer 1 according to Embodiment 1 of the present invention, the partial large amplitude of the divided vibration can be suppressed, so that abnormal noise and disturbance of the sound pressure frequency characteristics are prevented. be able to. Further, since no weight is added to the vibration film 20 itself, the influence on driving of the vibration film 20 can be reduced.

  In addition, although the electromagnetic transducer 1 which concerns on Embodiment 1 of this invention demonstrated it by braiding and supporting the four thin film sheets 21 in the vibration membrane 20, it is not restricted to this, The vibration membrane of the electromagnetic transducer 1 The number of thin film sheets 21 is changed according to the amplitude of 20 and the configuration of the electromagnetic transducer 1.

  Moreover, although the thin film sheet 21 of the electromagnetic transducer 1 according to Embodiment 1 of the present invention has been described using the same polymer resin as the base material 20a of the vibration film 20, the present invention is not limited to this, and the vibration film A lightweight acetate sheet, cloth sheet, paper sheet or the like that has little influence on the vibration of 20 may be used. Moreover, as for these sheets, it is desirable that the part which contacts the conductor coil 20b which becomes high temperature at the time of electricity supply is a material with high heat resistance.

  Moreover, in the electromagnetic transducer 1 which concerns on Embodiment 1 of this invention, although comprised using the rod-shaped permanent magnet as the permanent magnet 10, instead of a rod-shaped permanent magnet, polarity is alternated with a fixed space | interval. It is also possible to use plate-like permanent magnets that are magnetized differently. Even if the electromagnetic transducer 1 is configured using the plate-like permanent magnet, the same effects as those of the first embodiment of the present invention can be obtained, and further sufficient mechanical strength can be provided.

It is a figure which shows the structure of the electromagnetic transducer which concerns on Embodiment 1 of this invention. It is sectional drawing which shows operation | movement of the electromagnetic transducer which concerns on Embodiment 1 of this invention. It is sectional drawing which shows operation | movement of the conventional electromagnetic transducer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electromagnetic transducer, 10 Permanent magnet, 11 Upper permanent magnet, 12 Lower permanent magnet, 20 Vibration membrane, 20a Base material, 20b Conductor coil, 21 Thin film sheet, 22 Cut, 30 frame, 31 Upper frame, 31a Sound emission hole 32 Lower frame, 32a Sound release hole.

Claims (1)

A conductor coil made of a meandering conductor coil pattern is formed at a position opposite to a plurality of permanent magnets arranged in parallel and facing a gap portion between different magnetic poles of the permanent magnet, and a plurality of cuts are provided. A vibrating membrane,
A thin film sheet knitted into the vibrating membrane through the cut provided in the vibrating membrane;
A frame for holding the permanent magnet, the vibrating membrane and the thin film sheet;
Electromagnetic transducer with

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