JP2018074471A - Electroacoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weight electroacoustic transducer that can be adapted to a small output.SOLUTION: An electroacoustic transducer has: a diaphragm 12; a frame 16 which holds the diaphragm 12 in a peripheral area of the diaphragm 12; a voice coil 18 fixed inside the frame 16; and a magnet 20 which has a pair of parallel surfaces, in which one of the pair of parallel surfaces is magnetized in N-pole and the other one is magnetized in S-pole, and inside the voice coil 18, an axis line of the voice coil crosses the pair of parallel surfaces, and which is arranged in a reciprocable manner along an axial direction of the voice coil 18. The magnet 20 is fixed on a surface on a side facing the voice coil 18 at the center of the diaphragm 12 on one of the pair of surfaces.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electroacoustic transducer, and more particularly to an electroacoustic transducer that can be suitably used for headphones.

  In recent years, a speaker has been developed that vibrates a diaphragm when a voice coil is fixed and a magnet moves. As such a speaker, for example, a stator coil formed in a cylindrical shape is fixed in a cylindrical magnetic gap of a magnetic circuit, and inner and outer surfaces are attached to different polarities so as to be movable in the axial direction in the magnetic gap. There is a speaker in which a magnetized cylindrical field magnet is provided, and a dust intrusion prevention portion is formed by extending the end of a vibrating body interlocked by the vibration movement of the field magnet in the axial direction (Patent Document 1).

  There is also a speaker in which a thin film magnet is formed on both surfaces of a vibration film made of a polymer film with a magnetic material such as cobalt chrome, and a diaphragm in which the thin film magnet is magnetized in the thickness direction is disposed in an air-core coil ( Patent Document 2).

Japanese Unexamined Patent Publication No. 01-258594 JP 2004-56771 A

  An object of this invention is to provide the electroacoustic transducer which is lightweight and can respond also to a small output.

According to a first aspect of the present invention, there is provided a diaphragm, a frame that elastically supports a peripheral portion of the diaphragm,
The voice coil fixed inside the frame, one end face is magnetized to N pole, the other end face is magnetized to S pole, and can reciprocate along the axial direction of the voice coil inside the voice coil And an electroacoustic transducer having a magnet mounted on the back surface of the central portion of the diaphragm.

  In the electroacoustic transducer of the first aspect, a magnet magnetized with one end face being an N pole and the other end face being an S pole is capable of reciprocating along the axial direction of the voice coil inside the voice coil. It is set as the structure provided in. Therefore, the configuration is simple.

  In addition, since the magnet is reduced in size and reduced in weight and is effectively driven even for a small output sound signal, the electroacoustic transducer of the first aspect can cope with a small output. Furthermore, since both the inner diameter and the outer diameter of the voice coil can be reduced, the entire electroacoustic transducer can be easily downsized.

  According to a second aspect of the present invention, there is provided the electroacoustic transducer according to the first aspect, wherein the electroacoustic transducer has a magnet fixing member for fixing the magnet to the back surface at the center of the diaphragm.

  In the electroacoustic transducer of the second aspect, the magnet is fixed to the back surface at the center of the diaphragm by the magnet fixing member. Therefore, the diaphragm and the magnet are securely fixed.

According to a third aspect of the present invention, in the electroacoustic transducer according to the second aspect, an opening is formed in the central portion of the diaphragm, and a hole penetrating the end surface is formed in the magnet. ,
One end of the magnet fixing member is a large-diameter portion, which is inserted and fixed in the opening, and the other end is a small-diameter portion inserted and fixed in the hole.

  In the electroacoustic transducer of the third aspect, the large-diameter portion formed at one end of the magnet fixing member is fixed to the opening at the center of the diaphragm, and the small-diameter portion formed at the other end is the magnet hole. Since it is inserted and fixed, the fixing of the magnet fixing pin to the diaphragm and the magnet is reliable.

  According to a fourth aspect of the present invention, in the electroacoustic transducer according to the second aspect, an opening is formed in a central portion of the diaphragm, and a hole penetrating the end surface is formed in the magnet. One end of the magnet fixing member is a small-diameter portion, the small-diameter portion is inserted into and fixed to the hole of the magnet through the opening, and the other end of the magnet fixing member is a large-diameter portion. A diameter part is related with what is fixed to a peripheral part of an opening of the diaphragm.

  In the electroacoustic transducer of the fourth aspect, not only the small diameter portion of the magnet fixing pin is inserted and fixed in the center hole of the magnet, but also the large diameter portion of the magnet fixing pin is fixed to the peripheral portion of the opening of the diaphragm. Therefore, not only the fixing between the magnet fixing pin and the magnet but also the fixing between the magnet fixing pin and the diaphragm is reliable.

  According to a fifth aspect of the present invention, in the electroacoustic transducers according to the first to fourth aspects, the winding direction of the winding with respect to the central portion in the axial direction of the voice coil is defined as one end side and the other end side of the voice coil. It is related to what is the opposite direction.

  In the electroacoustic transducer of the fifth aspect, the winding direction of the winding of the voice coil is reversed between the one end side and the other end side with respect to the central portion in the axial direction of the voice coil. Therefore, the magnetization direction is also opposite on the one end side and the other end side with respect to the axial center portion, so the magnetic field generated on one end side and the magnetic field generated on the other end side are the axial center portion of the voice coil. Strengthen each other. Therefore, since the magnet receives a larger electromagnetic force in the voice coil, the diaphragm can be vibrated with a larger amplitude by the audio signal having the same output.

  As described above, according to the present invention, there is provided an electroacoustic transducer that is lightweight and can cope with a small output.

FIG. 1 is a cross-sectional view of the electroacoustic transducer according to Embodiment 1 cut along an axis. FIG. 2 is a partially broken perspective view illustrating an internal configuration of the electroacoustic transducer according to the first embodiment. FIG. 3 is a cross-sectional view of the electroacoustic transducer according to Embodiment 2 cut along an axis. FIG. 4A is a cross-sectional view of the voice coil included in the electroacoustic transducers according to the first to third embodiments, cut along the axis of the voice coil. FIG. It is a top view which shows the structure of the separator provided. FIG. 5 is a schematic diagram showing the operation of the voice coil shown in FIG. FIG. 6 is a schematic diagram showing the operation of the voice coil shown in FIG. FIG. 7 is a plan view of an example of a diaphragm included in the headphones according to the first to third embodiments. 8 is a cross-sectional view showing a cross section of the diaphragm shown in FIG. 7 cut along the axis. FIG. 9 is a plan view of another example of the diaphragm included in the electroacoustic transducers according to the first and second embodiments. FIG. 10 is a cross section of the diaphragm shown in FIG. 9 cut along the axis. FIG. 11 is a plan view illustrating a configuration of a frame included in the electroacoustic transducers according to the first and second embodiments. FIG. 12 is a cross-sectional view showing a cross section of the frame shown in FIG. 11 cut along the axis. FIG. 13 is a cross-sectional view showing a cross section of the magnet fixing member cut along the axis. FIG.

1. Embodiment 1
An example of the electroacoustic transducer of the present invention will be described below.
<Configuration>
As shown in FIGS. 1 and 2, the electroacoustic transducer 1 according to the first embodiment is fixed to a diaphragm 12, a frame 16 that elastically holds the diaphragm 12, and a center portion of a bottom surface 16 </ b> A of the frame 16. A voice coil 18 that is an air-core coil, a washer-like magnet 20 housed inside the voice coil 18, and a magnet fixing pin 24 as an example of a magnet fixing member that fixes the magnet 20 to the diaphragm 12. Have.

  As shown in FIGS. 7 and 8, the diaphragm 12 has a conical surface shape that curves in a convex shape toward the front, that is, in the direction in which sound is radiated, and is recessed toward the center as a whole. An opening 13 is formed at the top of the diaphragm 12, in other words, at the center. The diaphragm 12 is made of a fiber material such as paper or non-woven fabric, a plastic material such as PET resin, polyimide resin, polyether / ether / ketone resin, polypropylene resin, or a film such as a mixture thereof.

  An edge 14 formed of an elastic material such as rubber is provided on the outer periphery of the diaphragm 12 over the entire circumference of the diaphragm 12. The edge 14 has a semicircular concave or wavy cross section, but may have a semicircular protruding cross section or a circular or elliptical closed cross section. The diaphragm 12 and the edge 14 may be formed integrally.

  As shown in FIGS. 9 and 10, ribs 15 that spirally extend from the central portion toward the peripheral portion may be formed on the surface of the diaphragm 12. In the example shown in FIGS. 9 and 10, the rib 15 is formed so as to protrude forward from the surface of the diaphragm 12, but is rearward from the surface of the diaphragm 12, that is, the direction in which sound is radiated. On the contrary, it may be formed so as to protrude in the direction. By forming the rib 15 on the diaphragm 12, the rigidity of the diaphragm 12 is increased, so that the high sound reproduction characteristic of the electroacoustic transducer 1 is further improved.

  As shown in FIG. 4A, the voice coil 18 is an air-core coil, and includes a separator 19 located at the center in the axial direction, a one end side coil 18A located on one end side with respect to the separator 19, and a separator. 19 and the other end side coil 18B located on the other end side. Therefore, the voice coil 18 is divided into one end side coil 18A and the other end side coil 18B with the separator 19 as a boundary. The separator 19, the one end side coil 18A, and the other end side coil 18B are integrally formed.

  The one end side coil 18 </ b> A and the other end side coil 18 </ b> B have the same inner diameter B and outer diameter A, but the winding direction of the winding is as shown in FIGS. The directions are opposite to each other. The winding end portion of the one end side coil 18A and the winding start portion of the other end side coil 18B are connected by a crossover 18C.

  On the other hand, as shown in FIG. 4B, the separator 19 is a washer-like member made of an insulating material and has the same inner diameter as the inner diameter B of the voice coil 18, but the outer diameter C is one end side. It is larger than the outer diameter A of the coil 18A and the other end side coil 18B. The separator 19 is formed with a slit 19A through which the winding start portion of the one end side coil 18A is inserted, and a slit 19B through which the connecting wire 18C is inserted.

  The voice coil 18 is fixed to the bottom surface 16 </ b> A of the frame 16 at the separator 19.

  The above example is an example in which the voice coil 18 is a bobbin-less coil. However, the bobbin is integrally formed on both surfaces of the separator 19, and windings are wound around the respective bobbins in opposite directions to each other. A voice coil 18 formed with 18A and the other end side coil 18B can also be preferably used.

  The magnet 20 has one end face magnetized to the N pole and the other end face face magnetized to the S pole, and has a washer-like shape as a whole, with one end face and the other end face at the center. A through hole 21 is formed.

  As shown in FIG. 13A, the magnet fixing pin 24 is provided as a large-diameter portion and a small-diameter portion provided adjacent to the head 23 and having an outer diameter smaller than that of the head 23. Legs 25. The head 23 is formed in a hemispherical shape, in other words, a dome shape as a whole. A step 26 is formed between the head 23 and the leg 25. Moreover, the part adjacent to the leg part 25 of the head 23, in other words, the base part, is a flange-like part 28 protruding in a flange shape toward the radially outer side over the entire circumference. A step 27 is also formed between the outer peripheral surface of the head 23 and the flange-shaped portion 28. The magnet fixing pin 24 is further provided with a cavity 24A along the axis.

  As shown in FIG. 1, the head 23 of the magnet fixing pin 24 is inserted through the opening 13 of the diaphragm 12 and is bonded and fixed to the inner peripheral surface of the opening 13. On the other hand, the leg portion 25 is bonded and fixed to the wall surface of the center hole 21. Here, the diaphragm 12 is positioned with respect to the head 23 by the step 27 abutting against the opening 13 of the diaphragm 12. On the other hand, in the leg portion 25, the step is brought into contact with the surface of the magnet 20 that is magnetized to the N pole, whereby the magnet 20 is positioned with respect to the leg portion 25.

  The magnet fixing pin 24 may be formed from a plastic material such as ABS resin, or may be formed from an aluminum alloy or a magnesium alloy. If the magnet fixing pin 24 is formed of a plastic material, it can be manufactured at low cost by an injection molding method. In addition, if the magnet fixing pin 24 is formed of an aluminum alloy or a magnesium alloy, the heat generated in the voice coil 18 can be effectively dissipated through the magnet 20 and the magnet fixing pin 24. Therefore, the electroacoustic transducer 1 Heat is effectively prevented from being generated.

As shown in FIGS. 1, 11, and 12, the frame 16 has a bottom surface 16A to which the voice coil 18 is fixed, and a side wall 16B that rises from the peripheral edge of the bottom surface 16A over the entire circumference of the bottom surface 16A. It is a bottomed cylindrical member. An opening 16C through which the other end side coil 18B of the voice coil 18 is inserted is formed at the center of the bottom surface of the frame 16, and a recess 16D to which the separator 19 is fixed is formed around the opening 16C. ing.
As shown in FIGS. 1 and 7 to 10, the edge 12 of the side wall portion 16 </ b> B of the frame 16 is fixed by an annular fixing member 17, so that the diaphragm 12 is elastic to the frame 16. Is held.

<Action and effect>
In the electroacoustic transducer 1, when an audio signal is input to the voice coil 18, the magnet 20 reciprocates along the axial direction of the voice coil 18 by an axial magnetic field generated in the voice coil 18.

  The reciprocating motion of the magnet 20 is transmitted to the diaphragm 12 via the magnet fixing pin 24, and thereby the diaphragm 12 vibrates to generate sound.

  In the electroacoustic transducer 1, the magnet 20 having one of the pair of end faces magnetized to the N pole and the other magnetized to the S pole is inside the voice coil 18, and the axis of the voice coil 18 is parallel to the pair of magnets. And is fixed to the top of the diaphragm 12 by a magnet fixing pin 24 and is held so that the inside of the voice coil 18 can reciprocate along the axial direction of the voice coil 18. Has been. Therefore, the electroacoustic transducer 1 has a simple configuration.

  The magnet 20 has a washer-like shape as a whole, and a central hole 21 is formed at the center. Therefore, since the dimensions of the voice coil 18 in the axial direction and the radial direction can be reduced according to the magnet 20, the headphone using the electroacoustic transducer 1 can be configured to be lightweight and compact.

  The one end side coil 18A and the other end side coil 18B of the voice coil 18 are provided concentrically with respect to the separator 19, but the winding directions of the windings are opposite. Therefore, when a voice signal is input to the voice coil 18, a reverse magnetic field is generated in the voice coil 18, as shown in FIGS.

  For example, as shown in FIG. 5, when a counterclockwise current flows through the one end side coil 18A, a clockwise current flows through the other end side coil 18B. Accordingly, the upper side in FIG. 5 of the one end side coil 18A becomes the N pole and the lower side becomes the S pole, the upper side in FIG. 5 of the other end side coil 18B becomes the S pole, and the lower side becomes the N pole. Therefore, in the voice coil 18, since the south poles strengthen each other at the portion between the one end side coil 18A and the other end side coil 18B, the magnet 20 exerts a downward force as shown by an arrow F in FIG. receive.

  On the other hand, when a clockwise current flows through the one end side coil 18A as shown in FIG. 6, a counterclockwise current flows through the other end side coil 18B. Accordingly, the upper side in FIG. 6 of the one end side coil 18A becomes the S pole and the lower side becomes the N pole, the upper side in FIG. 6 of the other end side coil 18B becomes the N pole, and the lower side becomes the S pole. Therefore, in the voice coil 18, since the N poles strengthen each other between the one end side coil 18A and the other end side coil 18B, the magnet 20 receives an upward force as shown by an arrow F in FIG.

  Thus, in the voice coil 18, the winding directions of the windings of the one end side coil 18A and the other end side coil 18B are opposite to each other, and therefore between the one end side coil 18A and the other end side coil 18B. Magnetic flux strengthens each other. Thereby, unlike the case where the winding directions of the one end side coil 18 </ b> A and the other end side coil 18 </ b> B are the same, the magnet 20 generates a large electromagnetic force along the axis of the voice coil 18. Therefore, even when a small output sound signal is input, a large sound can be generated.

  Further, in the magnet fixing pin 24, the outer peripheral surface of the head 23 is bonded and fixed to the inner peripheral surface of the opening 13 located at the top of the diaphragm 12, and the leg portion 25 is inserted and fixed in the center hole 21 of the magnet 20. It is set as the structure. As a result, the fixing between the magnet fixing pin 24 and the diaphragm 12 and the magnet 20 becomes more reliable as compared with the configuration in which the magnet 20 is directly bonded to the rear surface in the central portion of the diaphragm 12.

  Furthermore, since the head 23 of the magnet fixing pin 24 protrudes forward from the central portion of the diaphragm 12 in a dome shape, it is forward compared to the case where the central portion of the diaphragm 12 is flat. The sound radiation characteristics are improved.

2. Embodiment 2
Another example of the electroacoustic transducer of the present invention will be described below.
<Configuration>
As shown in FIG. 3, the electroacoustic transducer 2 according to the second embodiment has the same configuration as the electroacoustic transducer 1 according to the first embodiment except for the configuration of the magnet fixing pin 24.

  As shown in FIG. 13B, the magnet fixing pin 24 provided in the electroacoustic transducer 2 includes a head 23 formed as a whole in a hemispherical shape or a dome shape, and a cylindrical portion having a smaller diameter than the head 23. As shown in FIG. 3, the leg portion 25 is inserted not only into the center hole 21 of the magnet 20 but also into the opening portion 13 of the diaphragm 12 and bonded to the wall surface of the center hole 21. Fixed. The head 23 is bonded and fixed to the peripheral edge of the opening 13 on the front surface of the diaphragm 12, in other words, on the front surface. Therefore, the head 23 is located on the opposite side of the magnet 20 with the diaphragm 12 interposed therebetween. Note that the back surface of the diaphragm 12 and the surface of the magnet 20 on the side magnetized to the N pole are both bonded and fixed to each other.

  The configurations of the diaphragm 12, the frame 16, the voice coil 18, and the magnet 20 are as described in the first embodiment.

<Action and effect>
The operation is as described in the first embodiment. In addition to the effects of the headphones of the first embodiment, the effects are further as follows.
First, since the leg portion 25 which is a small diameter portion is inserted into the opening portion 13 of the diaphragm 12, the head portion 23 of the magnet fixing pin 24 is compared with the electroacoustic transducer 1 according to the first embodiment. Thus, the diameter of the opening 13 can be reduced.

  In addition, in a state where the magnet 20 is fixed to the diaphragm 12 with the magnet fixing pin 24, the diaphragm 12 is sandwiched between the magnet 20 and the head 23 of the magnet fixing pin 24, and thus the head 23 The magnet 20 is more firmly fixed to the diaphragm 12 as compared with a configuration in which the magnet 20 is inserted into and fixed to the opening 13 of the diaphragm 12.

  The electroacoustic transducer of the present invention can be used not only for headphones but also for general speakers.

DESCRIPTION OF SYMBOLS 1 Electroacoustic transducer 2 Electroacoustic transducer 3 Electroacoustic transducer 10 Diaphragm 12 Diaphragm 13 Opening part 14 Edge 16 Frame 16A Bottom surface 16B Side wall 16B Side wall part 16C Opening part 16D Recessed part 17 Fixing member 18 Voice coil 18A One end side Coil 18B Other end side coil 18C Crossover wire 19 Separator 20 Magnet 21 Center hole 23 Head 24 Magnet fixing pin 25 Leg portion 26 Step 27 Step 28 Flange-shaped portion

Claims (5)

A diaphragm,
A frame that elastically supports a peripheral portion of the diaphragm;
A voice coil fixed inside the frame;
One end face is magnetized to the N pole, and the other end face is magnetized to the S pole, and is disposed inside the voice coil so as to be reciprocable along the axial direction of the voice coil. A magnet mounted on the
An electroacoustic transducer. The electroacoustic transducer according to claim 1, further comprising a magnet fixing member that fixes the magnet to a back surface in a central portion of the diaphragm. An opening is formed at the center of the diaphragm, and the magnet is formed with a hole penetrating the end face.
The electroacoustic transducer according to claim 2, wherein one end of the magnet fixing member is a large-diameter portion, and is inserted and fixed in the opening, and the other end is a small-diameter portion that is inserted and fixed in the hole. An opening is formed at the center of the diaphragm, and the magnet is formed with a hole penetrating the end face.
One end of the magnet fixing member is a small-diameter portion, the small-diameter portion is inserted into and fixed to the hole of the magnet through the opening, and the other end of the magnet fixing member is a large-diameter portion. The electroacoustic transducer according to claim 2, wherein the electroacoustic transducer is fixed to a peripheral edge of the opening of the diaphragm.   The winding direction of the winding of the voice coil is set to be opposite in one end side and the other end side with respect to an axial direction center portion of the voice coil as a boundary. Electroacoustic transducer.