JP2016116177A - Bone conduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bone conduction device securing a degree of freedom of a design of a diaphragm, further having high efficiency, and capable of securing a high output even if configured to be miniaturized and reduced in weight.SOLUTION: A bone conduction device includes: a tubular body 2 with a bottom comprising a magnetic material; a diaphragm 3 provided over upper end parts of the tubular body 2; a magnet 5 fixed to a lower surface 3c side of the diaphragm 3, at least a part of the magnet being located inside the tubular body 2; a yoke 4 stood on an inner side bottom surface 2b of the tubular body 2, the upper end surface 4a thereof facing a lower end surface 5b of the magnet 5 via a gap; and a voice coil 6 disposed around the yoke 4 inside the tubular body 2. A proximity part 8 is provided in the tubular body 2, the proximity part extending to the inside toward a magnet side surface 5a and comprising a magnetic material facing the side surface 5a with a gap formed therebetween.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a bone conduction device suitably used as a vibration driver for a bone conduction speaker or microphone, and more particularly to an efficient bone conduction device capable of high output even if it is small and light.

  Conventionally, as this type of bone conduction device, for example, as disclosed in FIG. 1 of Patent Document 1, an extension (30) (30 ′) for supporting a diaphragm (70) is provided, and a voice coil (40 ) And a central magnetic pole (yoke) (50), and a diaphragm (70) on which the iron piece (60) is fixed is placed between the extensions (30) and (30 ′), and the iron piece (60) A structure with a magnet (90) attached to the top is provided. This structure simplifies the assembly process and reduces costs, and the size of the voice coil can be changed relatively freely because the magnet is located not on the outer periphery of the voice coil but on the top of the diaphragm. The range of adjustment is widened, and the entire device can be reduced in size and weight.

  However, according to the structure of the bone conduction device of the above-mentioned Patent Document 1, there is no magnet on the outer peripheral side of the voice coil, and the whole can be slimmed down. However, there was a certain limit to the increase in output.

  Therefore, the present applicant has already proposed a bone conduction device that can achieve further slimming and high efficiency (Japanese Patent Application No. 2014-61947). Specifically, a bottomed cylindrical body made of a magnetic material having a peripheral wall having an upper end opened and surrounding the opening over the entire circumference, a diaphragm provided across the opening of the cylindrical body, The magnet is fixed to the lower surface side of the diaphragm, and at least a part thereof is positioned in the cylindrical main body below the position of the upper end opening of the cylindrical main body, and is erected on the inner bottom surface of the cylindrical main body. A bone conduction device comprising a yoke facing the lower end surface of the magnet via a gap and a voice coil disposed around the yoke in the cylindrical main body has been proposed.

  According to the bone conduction device according to the previous proposal, the magnetic flux from the upper surface of the magnet fixed to the lower surface side of the diaphragm is captured by the upper end of the peripheral wall of the cylindrical main body, and the flow of the magnetic flux is uniform, compact and efficient. A circuit is formed, magnetic leakage to the outside is reduced, and it is possible to obtain a high output with a small size and light weight. However, the bone conduction device according to this proposal supplements the magnetic flux from the upper surface of the magnet at the upper end portion of the peripheral wall, and magnetic leakage that radiates outside through the diaphragm is inevitable. If the diaphragm is made of a magnetic material, magnetic leakage can be suppressed, but the material of the diaphragm is limited and the degree of freedom in design is reduced.

JP 2007-74693 A

  The problem to be solved by the present invention is that the material of the diaphragm having a large influence on the operation (vibration characteristics) is not limited, thereby ensuring a high degree of freedom while ensuring the degree of freedom in designing the diaphragm. The object is to provide a bone conduction device that can ensure high output even if it is compact and lightweight.

  In order to solve the above-mentioned problems, the present invention provides a bottomed cylindrical body made of a magnetic material, a diaphragm provided on an upper end portion or an inner wall of the cylindrical body, and upper and lower surfaces of the diaphragm. A magnet fixed to the lower surface facing the inner bottom surface of the cylindrical main body, a yoke standing on the inner bottom surface of the cylindrical main body and having an upper end facing the lower end surface of the magnet via a gap, Proximity comprising a voice coil disposed around the yoke in the cylindrical main body, and extending to the cylindrical main body toward the side surface of the magnet and facing the side surface through a gap. There is provided a bone conduction device comprising a portion.

  Here, it is preferable that the inner end portion of the proximity portion is opposed to the region above the lower end of the magnet side surface via the gap.

  Furthermore, it is preferable that a plate material made of an electromagnetic steel plate is interposed between the magnet and the lower surface of the diaphragm.

  The present invention also provides a bottomed cylindrical body made of a magnetic material, a diaphragm provided on an upper end portion or an inner wall of the cylindrical body, and an inner bottom surface of the cylindrical body among the upper and lower surfaces of the diaphragm. The lower end surface of the cylindrical body is fixed to the inner bottom surface of the cylindrical main body through a gap, and a voice coil disposed around the magnet in the cylindrical main body. There is also provided a bone conduction device, wherein the cylindrical main body is provided with a proximity portion made of a magnetic material that extends inward toward the side surface of the magnet and faces the side surface through a gap.

  Here, it is preferable that a yoke is interposed between the magnet and the lower surface of the diaphragm.

  According to the bone conduction device according to the present invention as described above, most of the magnetic flux from the upper surface side of the magnet fixed to the lower surface side of the diaphragm is efficiently guided to the cylindrical body through the proximity portion, It is guided to the lower surface side of the magnet through the cylindrical main body. The direction of the magnetic flux is not limited, and the reverse case is the same. As a result, an efficient magnetic circuit is formed even if the diaphragm is made of a non-magnetic material, and while maintaining the degree of freedom in designing the diaphragm, magnetic leakage to the outside is extremely reduced and the output is increased with a compact structure. Can be achieved.

  In addition, since the inner end of the proximity portion faces the region above the lower end of the magnet side surface via the gap, a part of the magnetic force lines from the lower surface of the magnet enter the proximity portion and the magnetic field is shortcut. Moreover, the possibility that the output is reduced can also be prevented.

  In addition, since a plate material made of an electromagnetic steel plate is interposed between the magnet and the lower surface of the diaphragm, more magnetic flux from the upper surface side of the magnet can be more efficiently guided to the cylindrical main body through the proximity portion.

  In addition, since a yoke is interposed between the magnet and the lower surface of the diaphragm, more magnetic flux from the upper surface side of the magnet can be more efficiently guided to the cylindrical body through the proximity portion, and the yokeless consisting of only the magnet Compared with the case, the output is also improved.

The perspective view which shows the bone conduction device which concerns on 1st Embodiment of this invention. The longitudinal cross-sectional view of a bone conduction device similarly. Similarly disassembled perspective view. The perspective view which shows the bone conduction device which concerns on 2nd Embodiment of this invention. The longitudinal cross-sectional view of a bone conduction device similarly. Similarly disassembled perspective view. Similarly, the longitudinal cross-sectional view which shows the modification of the bone conduction device of 2nd Embodiment. The longitudinal cross-sectional view which shows another modification similarly. The perspective view which shows the bone conduction device which concerns on 3rd Embodiment of this invention. The longitudinal cross-sectional view of a bone conduction device similarly. Similarly disassembled perspective view. The longitudinal cross-sectional view which shows the bone conduction device which concerns on 4th Embodiment of this invention. Similarly, the longitudinal cross-sectional view which shows the modification of the bone conduction device of 4th Embodiment. Explanatory drawing which shows the structure of the model of Example 3. FIG. Explanatory drawing which shows the structure of the model of the comparative example 1. FIG. Explanatory drawing which shows the structure of the model of the comparative example 2. FIG. Explanatory drawing which shows the structure of the model of the comparative examples 3 and 4. FIG. Explanatory drawing which shows the structure of the model of the comparative examples 5 and 6. FIG. Explanatory drawing which shows the structure of the model of the comparative example 7. FIG. The simulation result of magnetic flux density distribution of Example 3. The simulation result of the magnetic flux density distribution of the comparative example 1. The simulation result of magnetic flux density distribution of Example 4. The simulation result of magnetic flux density distribution of Example 5. The simulation result of the magnetic flux density distribution of Example 6. The simulation result of magnetic flux density distribution of Example 7. FIG. The simulation result of the magnetic flux density distribution of Example 8. The simulation result of magnetic flux density distribution of Example 9. FIG. The simulation result of the magnetic flux density distribution of Example 10. FIG. The simulation result of the magnetic flux density distribution of Example 11.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  First, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 to 3, the bone conduction device 1 according to the present embodiment has a bottomed cylindrical main body 2 made of a magnetic material provided with a peripheral wall 2 c that extends over the entire circumference, and an upper end portion of the cylindrical main body 2. A diaphragm 3 to be provided, a magnet 5 that is fixed to the lower surface 3c side of the diaphragm 3, and at least a part thereof is positioned inside the cylindrical body 2, and an inner bottom surface 2b of the cylindrical body 2 The end surface 4a is composed of a yoke 4 facing the lower end surface 5b of the magnet 5 with a gap, and a voice coil 6 disposed around the yoke 4 in the cylindrical main body 2.

  In particular, the cylindrical body 2 is provided with a proximity portion 8 made of a magnetic material that extends inward toward the magnet side surface 5a and faces the side surface 5a with a gap. Most of the magnetic flux from the upper surface side of the magnet 5 is efficiently guided to the cylindrical main body 2 through the proximity portion 8, and there is very little magnetic leakage to the outside, so that an efficient magnetic circuit is formed. As a result, the entire device can be made compact and the output can be improved.

  The cylindrical main body 2 is a bottomed case in which a yoke 4, a magnet 5 and a voice coil 6 are arranged on the inner side. In this example, it is comprised from the inner side cylindrical part 20 formed with a magnetic material, and the outer side coating | coated part 21 formed with a nonmagnetic material, and the proximity | contact part 8 is provided inside the upper end of the inner cylindrical part 20. FIG. The non-magnetic outer covering portion 21 is formed with a fixing portion 23 for fixing the diaphragm 3 at the upper end. On the other hand, the inner cylindrical portion 20 made of a magnetic material has a uniform shape in the circumferential direction without such a complicated structure, and the magnetic flux from the magnet 5 is uniformly and efficiently guided through the inner cylindrical portion 20 without being disturbed. It is configured to be.

  Specifically, the inner cylindrical portion 20 is an annular member as the proximity portion 8 provided so as to close the opening toward the inside at the upper end of the peripheral wall 24 that forms a part of the peripheral wall 2c of the cylindrical main body 2 and the entire periphery thereof. 27 is a bottomed cylindrical body provided with 27 and a bottom wall 25. The peripheral wall 24 and the bottom wall 25 are configured by pressing a magnetic metal, for example, a stainless material of SUS430. The annular member 27 is a plate-like member that is similarly made of a stainless material such as SUS430, and is assembled to the upper end inner wall side of the peripheral wall 24.

  Specifically, a notch step 24c is formed on the inner surface of the upper end of the peripheral wall 24, and an annular member 27 is press-fitted into the notch step 24c. Of course, an assembly structure other than such press fitting may be used. Further, the proximity portion 8 may be configured by bending the upper region of the peripheral wall 24 inward rather than assembling the annular member 27 separately from the peripheral wall 24 as in this example. Moreover, the thing which provided the proximity | contact part 8 inside the middle part of the surrounding wall 24 like 3rd Embodiment mentioned later may be used.

  The peripheral wall 24 has a substantially uniform height (height in the vertical direction) and thickness (a thickness in the radial direction) over the entire circumference, and is a continuous curved surface having no corners when viewed from above, particularly a substantially circular shape (particularly, In this example, it is a perfect circular cylinder. That is, the entire surface of the peripheral wall 24 has no notches and holes, and has a uniform thickness and a uniform height over the entire circumference. Further, the proximity portion 8 (annular member 27) is also set to a substantially uniform thickness (vertical thickness) and a substantially uniform protruding length (radial length) over the entire circumference, and has a true circular shape in plan view. The gap between the side surface 5a of the magnet 5 and the inner end portion 8a (protruding tip portion) of the proximity portion 8 is configured to be uniform over the entire circumference.

  The protruding length of the proximity portion 8 is set so as to be a uniform gap as described above according to the shape and dimensions of the magnet 5. By forming the uniform gap in this way, a uniform and efficient magnetic circuit is formed in the circumferential direction by the proximity portion 8 and the peripheral wall 24. In the case where a plurality of proximity portions 8 are provided instead of a structure in which the proximity portions 8 are continuous over the entire circumference as in this example, a gap between the inner end portion 8a (protruding tip) of each proximity portion 8 and the magnet side surface 5a facing each other. Should be set so that they are all equal.

  The inner end portion 8a of the proximity portion 8 is opposed to a region above the lower end of the side surface 5a of the magnet 5 via a gap. Thereby, the shortcut of the magnetic force line between the lower surfaces of the magnet 5 is prevented. In FIG. 2, both lower end positions are drawn at the same height position, but at least the lower end position of the proximal inner end 8 a is at least lower than the lower end of the magnet side surface 5 a within the range of the stroke that moves relative to each other in the axial direction by vibration. Is also preferably maintained in the upper position.

  Note that the peripheral wall 24 and the adjacent portion 8 are not limited to a circular shape in plan view as in this example, but may be of an approximately elliptic shape or a rectangular shape or other polygonal shape or irregular shape although the uniformity is reduced. , Some may have notches and holes. In addition, it is not necessary for all of them to be present on the entire circumference, and those provided with a plurality of peripheral walls that rise intermittently from the bottom wall 25 in the circumferential direction, or those provided with a plurality of proximity portions protruding inward from the peripheral wall. Good. As described above, when a plurality of peripheral walls and adjacent portions are provided intermittently rather than continuously, it is preferable to provide them at equal intervals.

  A through hole 20c is formed in the center of the bottom wall 25 of the inner cylindrical portion 20 so as to fix the yoke 4 made of a magnetic material. A substantially cylindrical yoke 4 is fixed to the mounting hole 20c by caulking the bottom. Of course, the yoke 4 may be erected on the bottom wall 25 by other fixing methods such as welding. Further, instead of fixing the separately formed yoke 4 as in this example, the cylindrical body 2 (inner cylindrical portion 20) is integrally formed by machining or casting as in the second embodiment described later. But you can.

  The outer covering portion 21 includes a fixing portion 23 that is provided on the outer surface side of the inner cylindrical portion 20 and fixes the diaphragm 3. Specifically, it is a similarly bottomed tubular part formed by synthetic resin material on the outer surface side of the inner tubular part 20 by insert molding, and a plurality of flanges are provided as the fixing parts 23 on the outer peripheral part of the upper end. The diaphragm 3 is installed between the upper surfaces of the flanges (fixing portions 23).

  The outer covering portion 21 is formed in a state where the yoke 4 is fixed to the bottom surface of the inner cylindrical portion 20 in advance. Accordingly, the fixed portion (crimped portion) of the yoke 4 protruding downward from the mounting hole 20c of the inner cylindrical portion 20 is also buried in the synthetic resin constituting the outer covering portion 21, and the assembly strength of the yoke 4 is improved.

  In this example, similarly to the inner cylindrical portion 20, it is a bottomed cylindrical shape having a peripheral wall 26 that forms a part of the peripheral wall 2 c and extends around the entire circumference. However, other than such a structure, for example, one having a wall only at the flange (fixed portion 23) or one covered only in the upper end side where the flange (fixed portion 23) is formed may be used. This is because the outer covering portion 21 does not constitute a magnetic circuit, and therefore, even if the outer peripheral portion 21 does not have a uniform peripheral wall in the circumferential direction like the peripheral wall 24 of the inner cylindrical portion 20, it hardly affects the reduction or efficiency of magnetic leakage.

  Moreover, it is not restricted to what is shape | molded by insert molding, For example, the member separately shape | molded by the synthetic resin as the outer coating | coated part 21 at the cylindrical shape can also be assembled | attached and comprised to the outer side of the inner cylindrical part 20. Furthermore, the mounting structure of the diaphragm 3 can be changed as in a third embodiment described later, and the outer covering portion can be omitted.

  The diaphragm 3 includes an annular frame portion 30 fixed to the upper end portion of the cylindrical main body 2, specifically, the upper surface of the flange (fixing portion 23) of the outer covering portion 21, and the frame portion 30. And a connecting portion 32 for connecting the vibrating portion 31 to the frame portion 30 so as to be movable relative to the frame portion 30 in the axial direction (the axial direction of the cylindrical main body 2). And is made up of. The height of the upper surface of the fixing portion 23 to which the frame portion 30 is fixed is set to be the same as or higher than the upper end surface 22 of the inner cylindrical portion 20, and therefore the diaphragm 3 is substantially flat. Good.

  The diaphragm 3 is made of a non-magnetic material such as SUS304 stainless steel or carbon material. Therefore, although the diaphragm 3 does not constitute a magnetic circuit, the magnet 5 fixed to the lower surface of the diaphragm 3 is surrounded by the proximity portion 8 of the inner cylindrical portion 20 of the magnetic material, and the magnetic flux from the magnet 5 is in proximity. The part 8 is captured efficiently.

  Of course, the diaphragm 3 may be made of a magnetic material such as SUS430 in the same manner as the inner cylindrical portion 20. In this case, since the diaphragm 3 constitutes a magnetic circuit, the outer peripheral edge of the vibrating portion 31 is shaped along the upper outer edge of the peripheral wall 24 of the inner cylindrical portion 20 as in this example, By setting the inner side of the edge, the magnetic flux smoothly flows from the outer peripheral edge 31a to the peripheral wall 24 of the inner cylindrical part 20, and the magnetism leaks to the outer side of the inner cylindrical part 20. This can be suppressed. However, mechanical characteristics (spring characteristics) as a vibration material are deteriorated as compared with nonmagnetic stainless steel materials such as SUS304 and carbon materials.

  The vibration part 31 is provided with a mounting hole 31b for attaching a vibration transmission member (not shown). When used as a bone conduction speaker, the vibration of the vibration part 31 is transmitted to the scalp of the human body through the vibration transmission member. As a result, even a hearing-impaired person who has an abnormality in the tympanic membrane or ear ossicles in the skull of the human body can reliably hear the sound if the cochlea and the auditory nerve are normal.

  The magnet 5 has a substantially circular (perfect circle) cylindrical shape in plan view that is substantially similar to the inner peripheral surface of the inner cylindrical portion 20, and is substantially coaxial with the inner cylindrical portion 20 in the lower surface 3 c of the diaphragm 3. It is fixed at a position (substantially the center position of the vibration part 31), and the lower surface side is disposed so as to face the upper end surface 4a of the yoke 4 via a gap. Thereby, the magnet 5, the yoke 4, and the inner cylindrical portion 20 constituting the magnetic circuit are all arranged coaxially, and an efficient magnetic circuit in which the flow of magnetic flux is uniform is formed.

  As the shape of the magnet 5, a triangular prism shape, a pentagonal prism shape, and other various shapes can be adopted in addition to such a cylindrical shape. If the dimension (thickness) in the axial direction of the magnet 5 is thin, the magnetic flux loops through the proximity part 8 and the efficiency is lowered. Therefore, the dimension is preferably at least larger than the dimension (thickness) in the same direction of the proximity part 8. Is done.

  The voice coil 6 is fixed on the outer peripheral surface of the yoke 4 or on the bottom surface of the inner cylindrical portion 20 of the cylindrical main body 2. Both end portions of the coil wire of the voice coil 6 are drawn to the outside through the through hole 2 d on the bottom surface of the cylindrical body 2, and a sound signal or the like is input to the voice coil 6 from the outside.

  Next, a second embodiment of the present invention will be described based on FIGS.

  As shown in FIGS. 4 to 6, in the bone conduction device 1 of the present embodiment, the outer covering portion 21 is covered only on the outer side of the peripheral wall 24, and the covering of the bottom wall 25 is omitted. The outer surface (lower surface) of is exposed. The point which inserts the inner cylindrical part 20 and is shape | molded by a synthetic resin material is the same as the said 1st Embodiment.

  In the first embodiment, the yoke 4 is fixed by caulking, and the outer covering portion 21 covering the bottom wall 25 has the meaning of improving the assembling strength of the yoke. However, in this example, the yoke 4 is not assembled, but the inner cylindrical portion. It is integrally formed by cutting or casting at the center of the bottom wall 25 of 20. Therefore, even if the bottom wall 25 is not covered with the outer covering portion 21, there is no problem in terms of strength, and the structure can be reduced in material and weight. Of course, it is not limited to the one formed by insert molding, and for example, a member that is separately molded into a cylindrical shape by a synthetic resin may be assembled to the outside of the peripheral wall 24.

  Further, in the first embodiment, the diaphragm 3 has the vibrating portion 31 in a perfect circle, but in this example, the diaphragm 3 is long in the direction connecting the connecting portions 32 and 32 and has a deformed shape having a width equal to or larger than the outer diameter of the magnet 5. It is said that. The frame 30 also has a shape substantially along this except for the portion fixed by the mounting screw 7, and the peripheral wall 26 of the outer covering portion 21 also has a shape substantially along the outline of the frame 30 in plan view. Has been. In this way, the vibrating part 31 is configured to be elongated in plan view, and the frame part 30 and the outer covering part 21 have the minimum necessary structure corresponding thereto, whereby the entire driver can be reduced in size, and the vibrating part 31 is connected to the connecting part 32. , 32 is maintained in the direction of linking, so that a good vibration characteristic can be maintained.

  In addition, in this example, the attachment structure of the magnet 5 to the lower surface of the vibration portion 31 is formed by holding the magnet 5 from the side surface by a synthetic resin material and attaching the holder portion 9 to the lower surface of the vibration portion 31. More specifically, a communication hole 31c that penetrates up and down is formed around the region of the vibration portion 31 where the magnet 5 is attached, and the vibration plate 3 and the magnet 5 are inserted into a mold and molded with synthetic resin. . The holder portion 9 is integrally formed over and below the vibration portion 31 through the communication hole 31 c, and firmly holds the magnet 5 on the lower surface side of the vibration portion 31.

  The gap between the side surface 5a of the magnet 5 that is truly circular in plan view and the inner end 8a (protruding tip) of the proximity portion 8 is configured to be uniform over the entire circumference. The holder 9 made of synthetic resin, which will be described later, is held.

  The protruding length of the proximity portion 8 is set to be a uniform distance from the position of the side surface 5a of the magnet 5 to the last. By setting the uniform distance in this way, a uniform and efficient magnetic circuit is formed in the circumferential direction by the proximity portion 8 and the peripheral wall 24 regardless of the shape of the holder portion 9. In the case where a plurality of proximity portions 8 are provided, the distance between the inner end portion 8a (protruding tip) of each proximity portion 8 and the magnet side surface 5a facing each other may be set equal.

  The magnet 5 has a truncated cone shape whose diameter is reduced on the lower surface side. Therefore, the distance to the proximity portion 8 on the lower surface side is widened, and a structure in which a shortcut of the magnetic field does not easily occur. Similarly, as a structure for preventing a shortcut, as shown in FIG. 7, a notch portion 8 b is provided at a lower portion of the inner end portion facing the magnet side surface 5 a of the proximity portion 8. It is also preferable to increase the distance. If such a notch 8b is provided and the lower surface side of the magnet 5 is reduced in diameter, a shortcut can be prevented more reliably.

  Moreover, as shown in FIG. 8, it is a preferable embodiment to provide an electromagnetic steel plate 41 on the upper surface of the magnet 5. That is, the electromagnetic steel plate 41 is interposed between the magnet 5 and the vibrating portion 31 of the diaphragm. As a result, the magnetic flux on the upper surface side of the magnet 5 is efficiently guided to the proximity portion 8 through the electromagnetic steel plate 41, the magnetic leakage to the outside is further reduced, and an efficient magnetic circuit is formed.

  The other structures are basically the same as those in the first embodiment, and the same structures are denoted by the same reference numerals and description thereof is omitted.

  Next, a third embodiment of the present invention will be described with reference to FIGS.

  In the bone conduction driver 1 of the present embodiment, the outer covering portion 21 is omitted, and the diaphragm 3 is supported on the inner peripheral wall of the inner cylindrical portion 20. Specifically, a concave groove 24d is provided on the inner surface of the upper end of the peripheral wall 24 of the inner cylindrical portion 20, and the diaphragm 3 is supported by fitting the frame portion 30 of the diaphragm 3 into the concave groove 24d. Further, at a position below the concave groove 24d on the inner surface of the peripheral wall 24, a notch step portion 24c to which the annular member 27 as the proximity portion 8 is attached by press fitting is provided.

  As described above, in this embodiment, the outer covering portion 21 is omitted, and the mounting screw 7 for attaching the diaphragm 3 to the cylindrical main body 2 can also be omitted. Therefore, the material cost can be reduced, and the weight and size can be reduced. At the same time, assembly is easy, and the manufacturing cost can be reduced. In the inner cylindrical portion 20, a bottom wall 25 and a cylindrical peripheral wall 24 that are formed integrally with the yoke 4 are formed separately from each other and assembled to each other.

  A synthetic resin annular plate 28 on which the voice coil 6 is placed is interposed on the upper surface of the bottom wall 25 around the yoke 4. Specifically, the bottom wall 25 having the yoke 4 and the peripheral wall 24 are formed separately, and when the bottom wall 25 is press-fitted into the end of the peripheral wall 24 and fitted, the annular plate 28 is attached therebetween. The annular plate 28 is a circuit board, and the voice coil 6 is mounted on the annular circuit board so that productivity can be improved. That is, the end of the voice coil 6 is directly connected to the circuit pattern of the annular plate 28.

  In the diaphragm 3, the connecting portion 32 extends in a spiral manner from the center-side vibrating portion toward the outer frame portion 30 in an oblique manner in the circumferential direction. Thereby, the length of the connecting portion 32 is ensured, the vibration stroke can be secured, and the vibration capacity can be maintained even if the size is reduced.

  The other structures are basically the same as those in the first embodiment, and the same structures are denoted by the same reference numerals and description thereof is omitted.

  Next, based on FIG.12 and FIG.13, 4th Embodiment of this invention is described.

  The bone conduction driver 1 according to the present embodiment is configured by omitting the yoke 4 in the bone conduction driver 1 according to the second embodiment, and instead configuring the magnet 5 to be long downward, and the magnet lower end surface 5b is formed on the cylindrical body 2. The shape of the magnet 5 is such that it faces the bottom surface 2b (the bottom wall 25 of the inner cylindrical portion 20) via a gap, and there is no worry of a magnetic flux shortcut between the magnet lower end surface 5b and the inner end portion 8a of the proximity portion 8. It is not a conical shape but a cylindrical shape.

  The voice coil 6 is disposed around the magnet 5. In this example, the output is lower than that with a yoke, but the structure can be further downsized (thinned). Further, as shown in FIG. 13, it is also preferable that the yoke 4A is interposed between the magnet 5 and the vibration part 31 of the diaphragm 3 while omitting the yoke 4 from the bottom wall 25 of the inner cylindrical part 20. It is an embodiment. According to this, compared with the thing of FIG. 12, the magnetic flux of the magnet 5 upper surface side can be guide | induced to the proximity | contact part 8 more efficiently, magnetic leakage to the outside can be decreased, and an efficient magnetic circuit can be formed. . Others are basically the same as in the second embodiment, and the same reference numerals are given to the same structures, and the description thereof is omitted.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can of course be implemented in various forms without departing from the gist of the present invention.

  Hereinafter, analysis results obtained by calculating the sound pressure level and the magnetic flux density distribution by computer simulation for each of the models of Examples 1 to 9 and Comparative Examples 1 to 7 of the present invention will be described.

(Examples 1 to 3, Comparative Examples 1 and 2)
First, analysis results of each model of Examples 1 to 3 and Comparative Examples 1 and 2 according to the configuration of the first embodiment will be described.

  The models of Examples 1 and 2 have the structure shown in FIGS. 1 to 3, and the diaphragm has an outer diameter of 20 mm for the outer frame, an outer diameter of the vibrating portion of 14 mm, and a thickness of 0.5 mm. ) Made of SUS430 having an outer diameter of 14.5 mm, a height of 6.1 mm, and a thickness of 1 mm, an annular member in the proximity portion having an inner diameter of 8 mm, and a cylindrical main body (outer covering portion) of the peripheral wall and the bottom wall It is made of ABS resin with a thickness of 1.25 mm, the yoke is made of SS400 with an outer diameter of 4.5 mm, the height excluding caulking part is 3.35 mm, and the magnet is N-35 with an outer diameter of 7 mm and a thickness of 2 mm. The material was copper and the coil was copper wire. In Example 1, the material of the diaphragm was made of SUS304 (spring steel), and Example 2 was made of SUS430.

  The model of Example 3 has the structure shown in FIG. 14. The gap between the coil and magnet of the model of Example 2 is reduced by 1 mm, the thickness of the bottom of the outer cover is reduced by 0.5 mm, and the overall height is increased. This is a model reduced by 1.5 mm. Other dimensions and materials are the same as those of the model of Example 2, and the material of the diaphragm is made of SUS430.

  The model of Comparative Example 1 has the structure shown in FIG. 15, in which the annular member as the proximity portion and the notch step portion of the inner cylindrical portion to which this is attached are omitted from the structure of the model of Example 1. Other structures, dimensions, and materials are the same as the model of the first embodiment. Moreover, the model of the comparative example 2 is a structure shown in FIG. 16, and an annular member and a notch step part are abbreviate | omitted from the structure of the model of Example 3. FIG. Other structures, dimensions, and materials are the same as the model of the third embodiment. Table 1 summarizes the diagrams showing the models of Examples 1 to 3 and Comparative Examples 1 and 2 and the material of the diaphragm.

  Tables 2 and 3 show analysis results of displacement amounts and sound pressure levels of the models of Examples 1 to 3 and Comparative Examples 1 and 2, respectively. For these calculations, simulation software “JMAG” manufactured by JSOL Corporation was used. Specifically, the thrust of each model is calculated by the magnetic field analysis simulation program, and the displacement amount when the calculated thrust is applied to the diaphragm of each model is obtained by the structural analysis simulation. The sound pressure level (SPL) is determined by converting the calculated displacement amount into an amplitude value of the following equation 1 and converting it into sound pressure.

  The sound pressure (P, Pref) in Equation 1 is described as an amplitude value. In order to calculate the sound pressure level, it is converted into an effective value in parentheses. The sound pressure P at each node is calculated using the displacement speed of the surface set in the sound pressure condition. In this analysis, all surfaces of the model are surfaces set to sound pressure conditions.

  As can be seen from Tables 2 and 3, the model of Example 1, which differs from Comparative Example 1 which is a bone conduction driver without a proximity part, only in that the proximity part is provided, increases the sound pressure level at all frequencies. ing. Similarly, in comparison with Comparative Example 2 which is a model having no proximity portion, the model of Example 3 which is different only in that the proximity portion is provided has increased sound pressure levels at all frequencies. In the first and third embodiments according to the present invention, the proximity portion efficiently captures the magnetic flux of the magnet provided on the lower surface of the diaphragm, and an efficient magnetic circuit is formed. Seems to have increased at all frequencies.

  Further, in the comparison between Example 1 and Example 2 in which only the material of the diaphragm is different, there is no difference as compared with Comparative Example 1, but Example 2 has sound pressure levels at all frequencies compared to Example 1. This is considered to be the effect of using the diaphragm as a magnetic material. However, the sound pressure level in Example 1 in which the diaphragm is a non-magnetic material is higher than that in Comparative Example 2 in which the diaphragm is a magnetic material, and is closer than the effect of using the diaphragm as a magnetic material. The effect by the part is remarkable.

  20 and 21 show the analysis results of the magnetic flux density distribution of each model of Example 3 and Comparative Example 1. FIG. For the calculation of the magnetic flux density distribution, simulation software “JMAG” manufactured by JSOL Corporation was used.

  Compared with the magnetic flux density distribution of Example 3 in FIG. 20 and the magnetic flux density distribution of Comparative Example 1 in FIG. 21, in Example 3, the magnetic flux from the magnet is efficiently captured by the inner cylindrical portion, and the magnetic flux is efficiently in the yoke. It can be seen that the result is that the sound pressure level increases as described above.

(Examples 4-8, Comparative Examples 3-6)
Next, analysis results of the models of Examples 4 to 8 and Comparative Examples 3 to 6 according to the configuration of the second embodiment will be described.

  The models of Examples 4 and 5 have the structures shown in FIGS. 4 to 6, and the diaphragm has a maximum outer frame diameter of 21.5 mm, a minimum vibration portion diameter of 9.2 mm, and a thickness of 0.5 mm. The cylindrical main body (inner cylindrical part) is made of SUS430 having an outer diameter of 13.6 mm, a height of 5.3 mm, a peripheral wall thickness of 0.65 mm, and a bottom wall thickness of 1.0 mm, and an annular member in the proximity part Is made of SUS430 having an inner diameter of 8.4 mm and a thickness of 1.5 mm, and the cylindrical main body (outer covering portion) is made of ABS resin having a peripheral wall thickness of 0.3 to 1.6 mm, and is attached to the bottom of the inner cylindrical portion. The integrally formed yoke has an outer diameter of 4.5 mm and a height of 2.85 mm, and the magnet is a flat inverted cone made of N-35 material having an outer diameter of the upper surface of 7 mm, an outer diameter of the lower surface of 6 mm, and a thickness of 2 mm. It was trapezoidal and the coil was copper wire. In Example 4, the material of the diaphragm was made of SUS304 (spring steel), and Example 5 was made of SUS430.

  The models of Examples 6 and 7 have the structure shown in FIG. 7, and the outer diameter of the lower surface of the magnets of the models of Examples 4 and 5 is 7 mm, which is the same as the outer diameter of the upper surface. This is a model in which the shape is changed to a flat cylindrical shape and a notch is provided in the lower part of the inner peripheral surface of the annular member in the proximity portion. The material of the diaphragm is SUS304 in Example 6, and SUS430 in Example 7. Other dimensions and materials are the same as those of the model of Example 6 or Example 7.

  The model of Example 8 has the structure shown in FIG. 8, and a disk-shaped electromagnetic steel sheet having a thickness of 0.5 mm is interposed between the magnet upper surface and the diaphragm of the model of Example 4 above. Is a model in which the upper surface of the magnet is made thinner by the thickness of the electromagnetic steel sheet. The material of the diaphragm is SUS304 as in the fourth embodiment. Other dimensions and materials are the same as the model of the fourth embodiment.

  The models of Comparative Examples 3 and 4 have the structure shown in FIG. 17, and the annular member as a proximity portion and the notch step portion of the inner cylindrical portion to which the same is attached are omitted from the structures of the models of Examples 4 and 5, respectively. Is. Other structures, dimensions, and materials are the same as the models of Examples 4 and 5, respectively.

  The models of Comparative Examples 5 and 6 have the structure shown in FIG. 18, and the annular member and the notch step portion are omitted from the structures of the models of Examples 6 and 7, respectively. Other structures, dimensions, and materials are the same as the models of Examples 6 and 7, respectively.

  Table 4 summarizes the diagrams showing the models of Examples 4 to 8 and Comparative Examples 3 to 6, and the materials of the diaphragm. Table 5 shows the analysis results of the sound pressure levels of the models of Examples 4 to 8 and Comparative Examples 3 to 6. The calculation of the sound pressure level is the same as in the first embodiment.

  As can be seen from Table 5, the models of Examples 4-7 have increased sound pressure levels at all frequencies compared to the models of Comparative Examples 3-6, which differ only in that there is no proximity portion. In the first and third embodiments according to the present invention, the proximity portion efficiently captures the magnetic flux of the magnet provided on the lower surface of the diaphragm, and an efficient magnetic circuit is formed. Seems to have increased at all frequencies. Moreover, the model of Example 8 has an improved sound pressure level compared to the model of Example 4, and it can be seen that a more efficient magnetic circuit is formed by interposing an electromagnetic steel sheet.

  22 to 26 show the analysis results of the magnetic flux density distribution of each model of Examples 4 to 8. FIG. The calculation of the magnetic flux density distribution is the same as in the first embodiment. In either case, it can be seen that the magnetic flux from the magnet is efficiently captured by the inner cylindrical portion, the magnetic flux is efficiently concentrated on the yoke, and the sound pressure level is increased as described above.

Example 9
Next, the analysis result of the model of Example 9 according to the configuration of the third embodiment will be described.

  The model of Example 9 has the structure shown in FIGS. 9 to 11, and the diaphragm has a thickness of 0.2 mm, an outer diameter of the outer frame of 8.1 mm, an inner diameter of 7.3 mm, and an outer diameter of the vibration part. It is made of SUS304 (spring steel) with a length of 4 mm, a connecting part length of about 4.3 mm, and a width of 0.35 to 0.5 mm. The cylindrical main body (inner cylindrical part) has an outer diameter of 9 mm and a height of 4.2 mm. SUS430 with a peripheral wall thickness of 0.6mm and a bottom wall thickness of 0.5mm, and an annular member at the proximal portion made of SUS430 with an inner diameter of 4.2mm and a thickness of 0.5mm, integrated with the bottom of the inner cylindrical part The yoke has an outer diameter of 4 mm and a height of 2.1 mm, the magnet is an N-35 material having an outer diameter of 4 mm and a thickness of 1 mm, the thickness of the synthetic resin annular plate is 0.5 mm, and the coil is Copper wire was used.

  Table 6 shows a model of Example 9 and the material of the diaphragm. The analysis result of the sound pressure level of the model of Example 9 is as shown in Table 7. The calculation of the sound pressure level is the same as in the first embodiment.

  As can be seen from Table 7, the model of Example 9 has a sufficient sound pressure level despite its small size. This is presumably because the proximity portion efficiently captures the magnetic flux of the magnet provided on the lower surface of the diaphragm, and an efficient magnetic circuit is formed. In FIG. 27, the analysis result of the magnetic flux density distribution of the model of Example 9 is shown. The calculation of the magnetic flux density distribution is the same as in the first embodiment. It can be seen that the magnetic flux from the magnet is efficiently captured by the inner cylindrical portion, the magnetic flux is efficiently concentrated on the yoke, and the sound pressure level is increased as described above.

(Examples 10 and 11, Comparative Example 7)
Next, analysis results of the models of Examples 10 and 11 and the comparative example 7 according to the configuration of the fourth embodiment will be described.

  The model of Example 10 has the structure shown in FIG. 12, and the diaphragm is made of SUS304 (spring steel with a maximum outer frame diameter of 21.5 mm, a minimum vibration section diameter of 9.2 mm, and a thickness of 0.5 mm. ) Made of SUS430 having an outer diameter of 13.6 mm, a height of 5.3 mm, a peripheral wall thickness of 0.65 mm, and a bottom wall thickness of 1 mm, and an annular member in the proximity portion Is made of SUS430 having an inner diameter of 5 mm and a thickness of 1 mm, the cylindrical main body (outer covering portion) is made of ABS resin having a peripheral wall thickness of 0.3 to 1.6 mm, and the magnet has an outer diameter of 4 mm and a thickness ( The height was a cylindrical shape made of N-35 material with a 4.25 mm height, and the coil was a copper wire.

  The model of Example 11 has the structure shown in FIG. 13, and the difference from the model of Example 10 is that a cylindrical yoke made of SUS430 is interposed between the upper surface of the magnet and the diaphragm. The ratio of the magnet thickness (height) to the yoke height (thickness) is 1: 2, and the total height is the same as the magnet height of the tenth embodiment. The outer diameter of the yoke was 4 mm, similar to the magnet. Other dimensions and materials are the same as those in the tenth embodiment.

  The model of Comparative Example 7 has the structure shown in FIG. 19, in which the annular member as the proximity portion and the notch step portion of the inner cylindrical portion to which this is attached are omitted from the structure of the model of Example 10. Other structures, dimensions, and materials are the same as the model of the tenth embodiment.

  Table 8 summarizes the diagrams showing the models of Examples 10 and 11 and Comparative Example 7 and the material of the diaphragm. Table 9 shows the analysis results of the sound pressure levels of the models of Examples 10 and 11 and Comparative Example 7. The calculation of the sound pressure level is the same as in the first embodiment.

As can be seen from Table 9, the sound pressure level of the model of Example 10 is increased at all frequencies as compared to the model of Comparative Example 7 that differs only in that there is no proximity portion. In the tenth embodiment according to the present invention, since the proximity portion efficiently captures the magnetic flux of the magnet provided on the lower surface of the diaphragm and an efficient magnetic circuit is formed, the sound pressure level is at all frequencies. It is thought that it increased by.
The model of Example 11 has an improved sound pressure level compared to the model of Example 10, and a more efficient magnetic circuit is formed by interposing a yoke on the upper side of the magnet than using only the magnet. I understand that.

  28 and 29 show the results of analyzing the magnetic flux density distributions of the models of Example 10 and Example 11, respectively. The calculation of the magnetic flux density distribution is the same as in the first embodiment. It can be seen that the magnetic flux from the magnet is efficiently captured by the inner cylindrical portion, and the sound pressure level is increased as described above.

DESCRIPTION OF SYMBOLS 1 Bone conduction device 2 Cylindrical main body 2b Bottom face 2c Perimeter wall 2d Through-hole 3 Diaphragm 3c Lower face 4, 4A Yoke 4a Upper end surface 5 Magnet 5a Side surface 5b Lower end surface 6 Voice coil 7 Mounting screw 8 Proximity part 8a Inner end part 8b Notch Part 9 Holder part 20 Inner cylindrical part 20c Mounting hole 21 Outer covering part 22 Upper end surface 23 Fixed part 24 Peripheral wall 24c Step part 24d Groove 25 Bottom wall 26 Peripheral wall 27 Annular member 28 Annular plate 30 Frame part 31 Vibration part 31a Outer peripheral edge 31b Mounting hole 31c Communication hole 32 Connecting part 41 Electrical steel sheet s1 Clearance

Claims (5)

A bottomed cylindrical body made of a magnetic material;
A diaphragm provided on an upper end portion or an inner wall portion of the cylindrical body;
A magnet fixed to the lower surface side facing the inner bottom surface of the cylindrical body among the upper and lower surfaces of the diaphragm;
A yoke which is erected on the inner bottom surface of the cylindrical main body and whose upper end faces the lower end surface of the magnet via a gap;
A voice coil arranged around the yoke in the cylindrical body,
A bone conduction device, wherein the cylindrical main body is provided with a proximity portion made of a magnetic material that extends inward toward the side surface of the magnet and faces the side surface through a gap.   The bone conduction device according to claim 1, wherein an inner end portion of the proximity portion is opposed to a region above a lower end of a side surface of the magnet via the gap.   The bone conduction device according to claim 1 or 2, wherein a plate made of an electromagnetic steel plate is interposed between the magnet and the lower surface of the diaphragm. A bottomed cylindrical body made of a magnetic material;
A diaphragm provided on an upper end portion or an inner wall portion of the cylindrical body;
A magnet that is fixed to the lower surface side facing the inner bottom surface of the cylindrical main body of the upper and lower surfaces of the diaphragm, and whose lower end surface is opposed to the inner bottom surface of the cylindrical main body via a gap,
It consists of a voice coil arranged around the magnet in the cylindrical body,
A bone conduction device, wherein the cylindrical main body is provided with a proximity portion made of a magnetic material that extends inward toward the side surface of the magnet and faces the side surface through a gap.   The bone conduction device according to claim 4, wherein a yoke is interposed between the magnet and the lower surface of the diaphragm.