JP2007104633A - Electrokinetic electro-acoustic converter and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrokinetic electro-acoustic converter that is made small in size and low in profile without thinning the thickness of a magnet, and also to provide an electronic device with the electrokinetic electro-acoustic converter mounted thereon. <P>SOLUTION: The electrokinetic electro-acoustic converter includes: a first magnetic pole part including a magnet; a second magnetic pole part formed with at least one solid including a magnet, forming a magnetic gap between the second and the first magnetic pole and arranged in a space excluding the space above the upper surface and below the lower surface of the first magnetic pole in such a way that the lower surface of the solid is arranged above the upper surface of the first magnetic pole part; a yoke magnetically connecting the first magnetic pole part to the second magnetic pole part and supporting them; a diaphragm arranged in a space above the upper surface of the first magnetic pole part and in a space below the lower surface of the second magnetic pole part; and a voice coil arranged in the magnetic gap. The magnet of the first magnetic pole part is magnetized in a vibration direction of the diaphragm. The magnet of the second magnetic pole part is magnetized in a direction perpendicular to the vibration direction of the diaphragm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrodynamic electroacoustic transducer and an electronic device, and more specifically, is mounted on an electronic device such as a mobile phone, a PDA (Personal Digital Assistants), a television, a personal computer, a car navigation, and a portable player. The present invention relates to an electrodynamic electroacoustic transducer that reproduces an acoustic signal and an electronic device on which it is mounted.

  Conventionally, electronic devices such as mobile phones and PDAs have been reduced in thickness and power consumption. Along with that, electroacoustic transducers mounted on these devices are also desired to be smaller and more efficient. The most common method for increasing the efficiency of the electroacoustic transducer is to increase the volume of the magnet. However, when the volume of the magnet increases, the volume of the electroacoustic transducer itself increases. Therefore, in order to realize miniaturization and high efficiency, an electrodynamic electroacoustic transducer 200 as shown in FIG. 38 has been proposed (see, for example, Patent Document 1). FIG. 39 is a structural cross-sectional view of a conventional electrodynamic electroacoustic transducer 200.

  In FIG. 39, the electrodynamic electroacoustic transducer 200 includes a first magnet 211, a first yoke 212, a second magnet 213, a second yoke 214, a diaphragm 215, a voice coil 216, and a housing 217. Is provided.

  The first magnet 211 and the second magnet 213 are arranged to face both surfaces of the diaphragm 215 so as to sandwich the diaphragm 215, respectively. A magnetic gap is formed between the first magnet 211 and the second magnet 213 facing each other. Further, the surfaces of the first magnet 211 and the second magnet 213 opposite to the surfaces facing the diaphragm 215 are fixed to the first yoke 212 and the second yoke 214, respectively. Further, the first magnet 211 and the second magnet 213 are magnetized so that the polarities are opposite to each other in the vibration direction of the diaphragm 215.

  The first yoke 212 has a shape surrounding a surface of the first magnet 211 excluding the surface facing the diaphragm 215. Similarly, the second yoke 214 has a shape surrounding the surface of the second magnet 213 except for the surface facing the diaphragm 215. Further, the first yoke 212 and the second yoke 214 are fixed inside the housing 217, respectively.

  The diaphragm 215 is fixed inside the housing 217 having a sound hole, and is configured to be positioned in a gap formed between the first magnet 211, the second magnet 213, and the housing 217. The voice coil 216 is fixed to the diaphragm 215 and held in the magnetic gap. Hereinafter, the operation of the electrodynamic electroacoustic transducer 200 will be described.

  The first magnet 211 and the second magnet 213 are magnetized in directions opposite to each other and arranged to face each other. Therefore, the magnetic flux radiated from each magnet to the diaphragm side repels. Thereby, the magnetic flux vector bends substantially perpendicularly between the magnetic gaps, and draws a curve toward the yoke to which each magnet is fixed. For this reason, a magnetic field composed of magnetic flux perpendicular to the vibration direction of the diaphragm 215 is formed at the position of the voice coil 216 (hereinafter referred to as the voice coil position). When a current signal is passed through the voice coil 216 arranged on such a magnetic flux, a driving force proportional to the product of the magnitude of the current and the magnetic flux density at the voice coil position is generated. And the diaphragm 215 vibrates with the driving force, and a sound is radiated | emitted.

  In general electrodynamic electroacoustic transducers, the thickness of the voice coil is increased in the vibration direction of the diaphragm, whereas in this conventional example, the thickness of the voice coil 216 is decreased in the plane direction of the diaphragm 215. Constitute. Therefore, the thickness of the electrodynamic electroacoustic transducer 200 can be made thinner overall than the conventional electroacoustic transducer.

  Here, in general, an electrodynamic electroacoustic transducer generates abnormal noise when the vibrating portion of the diaphragm comes into contact with a portion other than the diaphragm of the transducer, so the maximum sound pressure required for the transducer is increased. It is designed so that the vibrating part of the diaphragm does not come into contact with any part other than the diaphragm of the converter even when it is reproduced. In the structure of the electrodynamic electroacoustic transducer 200 described above, the vibrating portion of the diaphragm 215 is the first magnet 211, the second magnet 213, the first yoke 212, and the second magnet when the diaphragm 215 has the maximum amplitude. In order not to come into contact with the yoke 214, it is necessary to ensure a sufficient distance between each of the diaphragms 215, that is, an amplitude margin. For this reason, in the structure of the electrodynamic electroacoustic transducer 200 described above, two magnetic circuits (a magnetic circuit composed of the first magnet 211 and the first yoke 212, the second magnet 213 and the second yoke) are provided. The thickness of the electrodynamic electroacoustic transducer 200 is the sum of the thickness of the magnetic circuit 214 and the amplitude margin on both sides of the diaphragm 215.

  Further, as an example of a conventional electromagnetic induction type electroacoustic transducer, an electromagnetic induction type electroacoustic transducer 300 as shown in FIG. 40 has been proposed in order to achieve miniaturization and high efficiency (for example, a patent) Reference 2). 40 is a structural cross-sectional view of a conventional electromagnetic induction electroacoustic transducer 300. FIG.

  In FIG. 40, the electromagnetic induction electroacoustic transducer 300 includes a magnet 311, a plate 312, a yoke 313, a driving primary coil 314, a diaphragm 315, and a secondary coil 316.

  The magnet 311 is fixed on the central axis of the yoke 313 having a sound hole. The plate 312 is fixed to the upper surface of the magnet 311. The driving primary coil 314 is located on the front side of the electromagnetic induction electroacoustic transducer 300 with respect to the magnet 311 and the plate 312. Further, the driving primary coil 314, the magnet 311 and the plate 312 are arranged so that their central axes coincide.

  A magnet 311 and a driving primary coil 314 are fixed to the yoke 313. The secondary coil 316 is fixed to the diaphragm 315 so as to be positioned in a magnetic gap formed between the magnet 311 and the plate 312 and a part of the yoke 313 on which the driving primary coil 314 is fixed. Is done. The magnetic gap is uniformly formed. The inner periphery of the secondary coil 316 is smaller than the outer periphery of the magnet 311. The outer periphery of the secondary coil 316 is larger than the inner periphery of the driving primary coil 314. The driving primary coil 314 is also fixed to the yoke 313 so as to be positioned in the magnetic gap. The diaphragm 315 is fixed to the yoke 313 via an edge. Hereinafter, the operation of the electromagnetic induction type electroacoustic transducer 300 will be described.

  In the electromagnetic induction electroacoustic transducer 300, when a current is passed through the driving primary coil 314, an induced magnetic field having a magnitude proportional to the time derivative of the change in the current is generated. A current is generated in the secondary coil 316 by the induced magnetic field. The secondary coil 316 generates a driving force proportional to the product of the current flowing through the secondary coil 316 and the magnetic flux density at the position of the secondary coil 316. Sound is radiated by the vibration of the diaphragm 315 by the driving force.

In this electromagnetic induction type electroacoustic transducer, it is generally necessary to dispose a driving primary coil 314 in the magnetic gap. For this reason, the magnetic gap length is increased by the amount corresponding to the primary coil for driving 314, and the magnetic flux density in the magnetic gap is reduced. As a result, there is a problem that efficiency is deteriorated. Therefore, in the electromagnetic induction type electroacoustic transducer 300, magnetic flux is generated in an oblique direction from the central axis of the diaphragm 315 to the front side, the thickness of the driving primary coil 314 is reduced, and the magnetic gap length is reduced. . As a result, the magnetic flux density at the position of the secondary coil 316 can be increased.
JP 2004-32659 A JP-A-10-276490

  However, in the above two conventional examples, when the thickness of the electroacoustic transducer is reduced for further thinning and miniaturization, it is necessary to further reduce the thickness of the magnet due to its structure.

  In the electrodynamic electroacoustic transducer 200 shown in FIG. 39, the first magnet 211, the first yoke 212, the second magnet 213, the second yoke 214, the diaphragm 215, and the voice coil 216 are all moved. The electric electroacoustic transducers 200 are arranged in the thickness direction. Therefore, in order to reduce the thickness of the electrodynamic electroacoustic transducer 200 as a whole, the thickness of any of the first magnet 211, the first yoke 212, the second magnet 213, and the second yoke 214 is used. Need to be reduced. However, when the magnet is thinned, the magnetic flux density at the position of the voice coil 216 is reduced, and the efficiency is lowered. In addition, magnets made from neodymium, which are generally used for small / thin speakers, tend to demagnetize at high temperatures as the temperature of the environment increases, so electrodynamic electroacoustics The reliability as a converter will fall remarkably. That is, there is a limit to making the magnet thinner while maintaining reliability. For these reasons, it has been difficult to reduce the thickness of the electrodynamic electroacoustic transducer 200 itself.

  In addition, the first magnet 211 and the second magnet 213 arranged on both sides of the diaphragm 215 are magnetized in the opposite directions. For this reason, there is a problem that the number of manufacturing steps is increased as compared with the case of magnetizing a single magnet and the case of magnetizing a plurality of magnets to the same pole.

  On the other hand, in the electromagnetic induction type electroacoustic transducer 300 shown in FIG. 40, a magnet 311, a plate 312, a diaphragm 315, a secondary coil 316, a driving primary coil 314, and a driving primary coil 314 are fixedly provided. A part of each yoke 313 overlaps in the thickness direction of the electromagnetic induction type electroacoustic transducer 300. Therefore, in order to make the entire electromagnetic induction electroacoustic transducer 300 thin while ensuring an amplitude margin, the thickness of the magnet 311 must be reduced. When the thickness of the magnet 311 is reduced, there is a problem that the reliability as the electroacoustic transducer is reduced as in the case of the electrodynamic electroacoustic transducer 200.

  Further, as described above, in the electromagnetic induction type electroacoustic transducer 300, the primary coil 314 for driving exists between the plate 312 constituting the magnetic gap having a uniform size and a part of the yoke 313. As a result, the distance of the magnetic gap becomes wider, and the magnetic flux density in the magnetic gap is lower than that of a general electrodynamic electroacoustic transducer. Therefore, if the thickness of the magnet 311 is reduced, the magnetic flux density in the magnetic gap is reduced as compared with the electrodynamic type, so that it is difficult to reduce the thickness of the electromagnetic induction electroacoustic transducer 300 itself.

  Further, in the electromagnetic induction type, the driving primary coil 314 and the secondary coil 316 are not electromagnetically coupled to each other by a core material that is a high-permeability magnetic body like a normal transformer (transformer). Coupled through air. Therefore, there is a problem that if the coupling coefficient is small and the thickness of the magnet 311 is reduced, the efficiency as the converter is further reduced. Further, in the electromagnetic induction type, since the induced magnetic field is generated in proportion to the time differentiation of the current, there is a problem that it is difficult to generate the electromagnetic induction current at a low frequency and it is difficult to reproduce the low frequency range.

  Therefore, an object of the present invention is to provide an electrodynamic electroacoustic transducer that can be reduced in size and thickness without reducing the thickness of the magnet, and an electronic device in which the electrodynamic electroacoustic transducer is mounted. Is to provide.

  In order to achieve the above object, the present invention has the following features.

  A first invention is an electrodynamic electroacoustic transducer, which is formed of at least one solid including at least one solid including a magnet, and at least one solid including a magnet. A second magnetic pole in which a three-dimensional lower surface is disposed above the upper surface of the first magnetic pole portion in a space excluding a space in the direction of the upper surface and the lower surface of the first magnetic pole portion by forming a magnetic gap with the first magnetic pole portion , A yoke that magnetically couples and supports a lower surface of the first magnetic pole portion and a side surface opposite to the magnetic gap of the second magnetic pole portion, and a space in the upper surface direction of the first magnetic pole portion And a diaphragm that is disposed in a space in the lower surface direction of the second magnetic pole portion and that is vibrated in the vertical direction with an outer periphery supported by a yoke, and a voice coil that is fixed to the diaphragm and disposed in the magnetic gap. The voice coil has its inner peripheral shape The second magnetic pole portion is larger than the outer peripheral shape of the first magnetic pole portion, and the second magnetic pole portion is disposed in a space excluding the space in the upper and lower direction of the first magnetic pole portion and the voice coil, and is included in the first magnetic pole portion. Is magnetized in the vibration direction of the diaphragm, the magnet included in the second magnetic pole portion is in a direction perpendicular to the vibration direction of the diaphragm, and the magnetic gap side is opposite to the pole on the top surface of the first magnetic pole portion. The diaphragm includes an edge portion that enables the diaphragm to vibrate, and at least a part of the edge portion faces the lower surface of the second magnetic pole portion.

  According to a second invention, in the first invention, at least one of the first magnetic pole part and the second magnetic pole part is composed of a plate made of a magnetic material not including a magnet and a magnet formed with two magnetic pole surfaces. The yoke is coupled to one magnetic pole surface of the magnet, and the plate is fixed to the other magnetic pole surface of the magnet.

  A third invention is characterized in that, in the first invention described above, the diaphragm is formed such that the shape of the portion facing the upper surface of the first magnetic pole portion is relatively convex with respect to other portions. To do.

  According to a fourth invention, in the first invention, the voice coil is fixed to either the upper surface side or the lower surface side of the diaphragm, and the diaphragm has a portion facing the upper surface of the first magnetic pole portion at the voice coil. The part which is above the lower end of this and which opposes the lower surface of a 2nd magnetic pole part is formed in the shape which exists below the upper end of a voice coil, It is characterized by the above-mentioned.

  In a fifth aspect based on the first aspect, the diaphragm is formed from a group consisting of a circle, a rectangle, an ellipse, a polygon, and a shape in which only two opposite sides of the rectangle or the polygon are formed as a semicircle. It is formed in any one shape selected.

  In a sixth aspect based on the first aspect, the first magnetic pole part and the second magnetic pole part are annular bodies having a gap formed in the center thereof, and the first magnetic pole part is the second magnetic pole part. It arrange | positions in the up-down direction space of the annular body space | gap which comprises a part, It is characterized by the above-mentioned.

  In a seventh aspect based on the first aspect, the first magnetic pole part is a columnar body, the second magnetic pole part is an annular body having a gap formed in the center thereof, and the first magnetic pole part Is arranged in the vertical space of the annular gap forming the second magnetic pole part.

  In an eighth aspect based on the first aspect, the voice coil has two straight portions facing part of the winding portion, and the first magnetic pole portion is provided on each of the two straight portions. The second magnetic pole portion includes two parallelepipeds each having a parallel side and including a magnet. The second magnetic pole portion includes two rectangular parallelepiped portions each including a magnet. The voice coil has one linear portion having a second magnetic pole portion. Is disposed in a magnetic gap formed between one of the first magnetic pole part and the other linear part in the magnetic gap formed between the other of the second magnetic pole part and the first magnetic pole part. It is characterized by being arranged in.

  In a ninth aspect based on the eighth aspect, the second magnetic pole part includes at least two or more rectangular parallelepipeds each including a magnet.

  According to a tenth aspect, in the eighth aspect, the first magnetic pole portion is two rectangular parallelepipeds each having a side parallel to each of the two linear portions and each including a magnet.

  An eleventh invention is characterized in that, in the eighth invention, an opening is formed in a part of the yoke including at least a portion facing the second magnetic pole portion.

  In a twelfth aspect based on the eleventh aspect, the diaphragm outside the winding portion of the voice coil is formed so as to protrude toward the opening portion at a portion facing the opening portion, and reverse at other portions. It is characterized by projecting to the side.

  A thirteenth aspect of the present invention is an electronic device on which an electrodynamic electroacoustic transducer is mounted, and the electrodynamic electroacoustic transducer includes a first magnetic pole portion formed of at least one solid including a magnet, A three-dimensional lower surface is formed in at least one three-dimensional body including a magnet, and a magnetic gap is formed between the first magnetic pole portion and a space excluding the upper surface and the lower surface direction of the first magnetic pole portion. Magnetically coupling the second magnetic pole portion disposed above the upper surface of the magnetic pole portion, the lower surface of the first magnetic pole portion and the side surface opposite to the magnetic gap of the second magnetic pole portion. A supporting yoke, a vibration plate disposed in a space in the upper surface direction of the first magnetic pole portion and a space in the lower surface direction of the second magnetic pole portion, the outer periphery of which is supported by the yoke and capable of vibrating in the vertical direction; Boys fixed to the plate and placed in the magnetic gap The voice coil has an inner peripheral shape larger than that of the first magnetic pole portion, and the second magnetic pole portion excludes the first magnetic pole portion and the space in the upper and lower surface directions of the voice coil. The magnets disposed in the space and magnetized in the first magnetic pole part are magnetized in the vibration direction of the diaphragm, and the magnets contained in the second magnetic pole part are magnetic gaps in a direction perpendicular to the vibration direction of the diaphragm. And the diaphragm includes an edge portion that allows the diaphragm to vibrate, and at least a part of the edge portion is the second magnetic pole portion. An electronic device characterized by facing the lower surface of the electronic device.

  According to the first aspect of the invention, since the first magnetic pole part and the second magnetic pole part have a structure that does not overlap with the vibration direction of the diaphragm, an electrodynamic electroacoustic transducer having the same thickness is realized. The magnets included in the first magnetic pole part and the second magnetic pole part can be made thicker in the vibration direction than in the prior art. As a result, the magnetic flux density at the voice coil position is improved, and a highly efficient electrodynamic electroacoustic transducer can be realized with the same thickness as the conventional one. Furthermore, magnets made from neodymium, which are generally used for small thin speakers, tend to demagnetize at higher temperatures as magnets with higher energy products. However, this configuration increases the permeance coefficient by increasing the magnet thickness. And strong against high temperature demagnetization. Therefore, it is possible to use a magnet having a higher energy product while improving the temperature reliability or maintaining the same temperature reliability. As a result, the magnetic flux density at the voice coil position can be further improved, so that a more efficient, small and thin electrodynamic electroacoustic transducer can be realized. In addition, a thin electrodynamic electroacoustic transducer that is impossible with the conventional magnetic circuit structure can be realized while maintaining the conventional temperature reliability. In addition, the present invention employs an electrodynamic electroacoustic transducer and does not use a primary coil for driving that causes a decrease in magnetic flux density in the magnetic gap in the conventional electromagnetic induction electroacoustic transducer. It is possible to provide an electroacoustic transducer with high efficiency even with the same thickness. Further, according to the present invention, the three-dimensional lower surface of the second magnetic pole part is disposed above the upper surface of the first magnetic pole part. In order to realize a thin electrodynamic electroacoustic transducer, the second magnetic pole part may be arranged obliquely with respect to the first magnetic pole part. Since a component perpendicular to both the winding direction and the amplitude direction of the voice coil exists, it is possible to drive the diaphragm. Therefore, it is possible to realize an electrodynamic electroacoustic transducer that is thinner than conventional ones. Furthermore, according to the present invention, when the voice coil vibrates, the first and second magnetic pole portions are not contacted. Thereby, a smaller and thinner electrodynamic electroacoustic transducer can be realized while securing a larger amplitude margin. Further, according to the present invention, the magnets included in the first magnetic pole part and the magnets included in the second magnetic pole part are different in magnetization direction, so that the magnetic flux can be generated more efficiently at the position of the voice coil. Can do. Further, since the magnet included in the second magnetic pole portion is magnetized in a direction perpendicular to the vibration direction of the diaphragm, it is necessary to fix the yoke on the upper portion of the magnet included in the second magnetic pole portion. Accordingly, the thickness can be further reduced by the thickness of the yoke.

  According to the second aspect of the present invention, the magnetic flux density at the voice coil position can be further improved by fixing the magnetic plate other than the magnet to the magnetic pole surface of the magnet. An electric electroacoustic transducer can be realized.

  According to the third and fourth aspects of the invention, the diaphragm, the first magnetic pole part, and the second magnetic pole part have a shape that is most difficult to come into contact by vibration. Therefore, the vibration plate is displaced in the direction of the first magnetic pole portion and the first amplitude is brought into contact with the upper surface of the first magnetic pole portion, and the vibration plate is displaced in the direction of the second magnetic pole portion and the second magnetic pole portion. It is possible to ensure a large second amplitude in contact with the lower surface of the magnetic pole portion. That is, for example, when the yoke supports the lower surface of the first magnetic pole part and the upper surface of the second magnetic pole part, respectively, the thickness of the yoke that supports each surface and the vibration of the first magnetic pole part and the second magnetic pole part. A thin electrodynamic electroacoustic transducer having a higher efficiency than the total thickness of the electrodynamic electroacoustic transducer, the value obtained by adding the length of the direction and the first and second amplitudes above. Can be realized.

  According to the fifth aspect of the present invention, by selecting an electrodynamic electroacoustic transducer having a diaphragm having an appropriate shape according to the space shape inside the housing of the electronic device or the like to be mounted, Space can be used without waste.

  According to the sixth aspect of the invention, since the first magnetic pole portion is an annular body in which a gap is formed, there is an effect that sound on the lower surface of the diaphragm is likely to escape downward due to the gap. Further, examples of the annular body of the second magnetic pole portion include a circle, an ellipse, or a polygonal annular body.

  According to the seventh aspect, by using, for example, a circular, elliptical, or polygonal columnar magnet in the first magnetic pole portion, it is advantageous in terms of cost compared to a ring-shaped magnet in which a gap is formed. can do.

  According to the eighth aspect of the invention, the voice coil and the diaphragm are arranged in the magnetic gap so that the voice coil and the diaphragm have, for example, a rectangular long shape or a land track shape. In addition, a driving force can be obtained at the linear portion of the voice coil.

  According to the ninth aspect of the invention, the second magnetic pole portion includes two or more rectangular parallelepipeds each including a magnet, so that even in the magnetizing direction of the magnet that is difficult to realize with one rectangular parallelepiped, This can be realized by combining a plurality of rectangular parallelepipeds.

  According to the tenth aspect, the space formed between the two rectangular parallelepipeds makes it easier for the sound on the lower surface of the diaphragm to escape downward.

  According to the eleventh aspect of the invention, the opening formed in the yoke makes it easier for sound on the lower surface of the diaphragm to escape downward. Further, when the thickness is reduced, the diaphragm is less likely to come into contact with the yoke.

  According to the twelfth aspect of the invention, the diaphragm and the yoke are less likely to come into contact with each other, and the thickness can be further reduced.

  In addition, an electronic device equipped with the electrodynamic electroacoustic transducer of the present invention can obtain the same effects as those of the electrodynamic electroacoustic transducer described above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
With reference to FIGS. 1-4, the electrodynamic electroacoustic transducer 1 which concerns on the 1st Embodiment of this invention is demonstrated. FIG. 1 is a structural cross-sectional view of the electrodynamic electroacoustic transducer 1 according to the first embodiment. FIG. 2 is a perspective view of a part of the electrodynamic electroacoustic transducer 1 cut out. 3 and 4 will be described later. In FIG. 1, the electrodynamic electroacoustic transducer 1 includes a first magnetic pole 11, a second magnetic pole 12, a yoke 13, a voice coil 14, and a diaphragm 15. In addition, as shown in FIG. 2, the shape of the electrodynamic electroacoustic transducer 1 seen from the vibration direction is a circular shape. The first magnetic pole 11 corresponds to the first magnetic pole part of the present invention, and the second magnetic pole 12 corresponds to the second magnetic pole part of the present invention.

  The first magnetic pole 11 includes a magnet 11a and a plate 11b fixed to the upper surface (magnetic pole surface) of the magnet 11a. The second magnetic pole 12 includes a magnet 12a and a plate 12b fixed to the lower surface (magnetic pole surface) of the magnet 12a. The plates 11b and 12b are magnetic bodies (for example, iron etc.) other than a magnet. As shown in FIG. 2, the first magnetic pole 11 has a cylindrical shape (columnar body), and the second magnetic pole 12 has a donut-shaped annular body.

  Here, the second magnetic pole 12 is located on the front side of the electrodynamic electroacoustic transducer 1 with respect to the first magnetic pole 11. Further, the first magnetic pole 11 and the second magnetic pole 12 are arranged so that their central axes coincide. Further, the inner peripheral shape (inner diameter) of the second magnetic pole 12 is larger than the outer peripheral shape (outer diameter) of the first magnetic pole 11. The lower surface of the second magnetic pole 12 is disposed at the same position as the upper surface of the first magnetic pole 11 or at least on the front surface side of the electrodynamic electroacoustic transducer 1 from the upper surface. In other words, the second magnetic pole 12 is positioned in an oblique front direction extending from the first magnetic pole 11, and is arranged such that a magnetic gap is formed between the first magnetic pole 11 and the second magnetic pole 12. . In addition, the magnetic gap between the 1st magnetic pole 11 and the 2nd magnetic pole 12 may be formed so that it may become a uniform dimension over the space which each opposes, for example.

  The yoke 13 fixes the lower surface of the first magnetic pole 11 and the upper surface of the second magnetic pole 12, respectively, and supports the first magnetic pole 11 and the second magnetic pole 12 by magnetic coupling. Here, the lower surface of the first magnetic pole 11 and the upper surface of the second magnetic pole 12 respectively correspond to one magnetic pole surface of the present invention. The voice coil 14 has an annular shape, is fixed to the diaphragm 15, and is held in the magnetic gap by the diaphragm 15. Further, the inner peripheral shape (inner diameter) of the voice coil 14 is configured to be larger than the outer peripheral shape (outer diameter) of the first magnetic pole 11. The outer peripheral shape (outer diameter) of the voice coil 14 is configured to be smaller than the inner peripheral shape (inner diameter) of the second magnetic pole 12. That is, the difference between the inner peripheral shape (inner diameter) of the second magnetic pole 12 and the outer peripheral shape (outer diameter) of the first magnetic pole 11 is the width of the voice coil 14 (that is, the outer diameter and inner diameter of the voice coil 14). Difference) is configured to be larger. The diaphragm 15 is disposed so that the outer periphery thereof is fixed to the yoke 13 and is located in a gap formed between the first magnetic pole 11, the second magnetic pole 12, and the yoke 13. Moreover, the shape of the diaphragm 15 viewed from the vibration direction is a circular shape. Due to the shape and positional relationship between the voice coil 14 and the first magnetic pole 11 and the second magnetic pole 12, the voice coil 14 and the first magnetic pole 11 or the second magnetic pole 12 even if the diaphragm 15 vibrates greatly. To prevent contact.

  Here, as shown in FIG. 1, the voice coil 14 is fixed to the diaphragm 15 so that the central portion of the diaphragm 15 has a convex shape with respect to the outer peripheral portion. Specifically, the central portion of the diaphragm 15 that is inside the inner peripheral shape of the voice coil 14 forms a convex shape. Further, the outer peripheral portion of the diaphragm 15 that is outside the outer peripheral shape of the voice coil 14 forms a concave shape. That is, the diaphragm 15 has a convex shape at a portion facing the first magnetic pole 11 and a concave shape at a portion opposed to the second magnetic pole 12. Due to the shape of the diaphragm 15, the diaphragm 15 and the first magnetic pole 11 and the second magnetic pole 12 are in a shape that is most unlikely to come into contact by vibration. Even if it comprises, magnet 11a and 12a can be thickened, ensuring the same amplitude margin. If such an effect is not expected, the diaphragm 15 does not have to be formed in the middle convex shape as described above. As described above, since the voice coil 14 and the first magnetic pole 11 or the second magnetic pole 12 are not in contact with each other, the magnets 11a and 12a are made thicker while ensuring the same amplitude margin with this structure alone. Can do. Further, as shown in FIG. 1, the central portion itself of the diaphragm 15 has a shape protruding toward its central axis. As a result, the rigidity of the central portion of the diaphragm 15 is increased, which is advantageous for high-frequency reproduction.

  Further, as shown in FIG. 1, an edge portion 15 a is formed on the outer peripheral portion of the diaphragm 15 that is outside the outer peripheral shape of the voice coil 14. The edge portion 15a allows the diaphragm 15 to vibrate in the vertical direction. The shape of the edge portion 15a itself may be a flat plate shape, but may be a shape whose cross section is a roll shape as shown in FIG. By making the shape of the edge portion 15a itself into a roll-shaped cross section, the restoring force with respect to the amplitude of the diaphragm 15 becomes more linear, and for example, the effect of further reducing distortion of reproduced sound and improving sound quality can be obtained. . As shown in FIG. 1, the edge portion 15 a is formed so that a part thereof faces at least the second magnetic pole portion 12. Therefore, the edge portion 15 a may be formed on the entire diaphragm 15 facing the second magnetic pole portion 12. The edge portion 15a may be configured integrally with the diaphragm 15 other than the edge portion 15a, or may be configured separately from the diaphragm 15 other than the edge portion 15a.

  The magnet 11a and the magnet 12a are magnetized to have the same polarity in the vibration direction of the diaphragm 15 (so that the polarities are in the same direction). The yoke 13 is formed with a sound hole for radiating sound to the front side of the electrodynamic electroacoustic transducer 1 and a sound hole for exhausting pressure on the back side. Hereinafter, the operation of the electrodynamic electroacoustic transducer 1 will be described.

  As described above, a magnetic gap is formed between the first magnetic pole 11 and the second magnetic pole 12. When a signal current flows through the voice coil 14 located in the magnetic gap, a driving force proportional to the product of the magnitude of the current and the magnetic flux density at the voice coil position is generated. Then, the diaphragm 15 vibrates by the driving force, so that sound is emitted. Thus, the electroacoustic transducer according to this embodiment is an electrodynamic type. That is, the electroacoustic transducer according to the present embodiment is a transducer that directly applies an electroacoustic signal to the voice coil 14, and is a transducer different from the electromagnetic induction type described above.

  Here, the conventional electrodynamic electroacoustic transducer has a structure in which a magnet and a yoke sandwich a diaphragm and a voice coil from above and below. Therefore, it is necessary to prevent the voice coil from coming into contact with the magnet and the yoke during vibration of the diaphragm, and the thickness of the magnet is limited. However, in the electrodynamic electroacoustic transducer 1 according to this embodiment, the inner circumference of the voice coil 14 is larger than the outer circumference of the first magnetic pole 11, and the outer circumference of the voice coil 14 is larger than the inner circumference of the second magnetic pole 12. Since it is configured to be small, the voice coil 14 does not contact the first magnetic pole 11 or the second magnetic pole 12 even if the diaphragm 15 vibrates greatly. In addition, by arranging the diaphragm 15 and the magnetic poles (the first magnetic pole 11 and the second magnetic pole 12) in a shape and a position where they are difficult to come into contact with each other by vibration, the electrodynamic electroacoustic transducer can be formed with the same thickness as the conventional one. Even if it comprises, magnet 11a and 12a can be thickened, ensuring the same amplitude margin. As a result, the magnetic flux density at the position of the voice coil 14 can be increased. Further, by increasing the thickness of the magnets 11a and 12a, the permeance coefficient is increased even when a high energy product magnet using neodymium or the like is used, and it is more resistant to high temperature demagnetization than in the past. That is, the temperature reliability of the electrodynamic electroacoustic transducer 1 is improved.

  Here, with reference to FIG. 3, the flow of the magnetic flux which the 1st magnetic pole 11 and the 2nd magnetic pole 12 in this embodiment comprise is demonstrated. FIG. 3 is a diagram showing an example of a magnetic circuit according to the present embodiment, in which a magnetic field analysis is performed by a finite element method, and a magnetic flux flow is represented by a vector. In FIG. 3, it can be seen that the magnetic flux passes through the voice coil 14 and a driving magnetic flux having a direction component perpendicular to the vibration direction is formed. Thus, since the first magnetic pole 11 and the second magnetic pole 12 are in an oblique positional relationship with respect to the vibration direction of the diaphragm 15, the magnet 11a and the magnet 12a are attached to the same polarity in the vibration direction. By magnetizing, a driving magnetic flux having a direction component perpendicular to the vibration direction is formed.

  FIG. 4 shows two examples of the conventional magnetic circuit shown in FIG. 39 and the magnetic circuit of the present embodiment shown in FIG. 1 under the condition that the thickness of the entire magnetic circuit and the material of the magnet are the same. It is the figure which compared the magnetic flux density in a voice coil position about a magnetic circuit. In FIG. 4, the horizontal axis represents the amplitude of the diaphragm 15, and the vertical axis represents the magnetic flux density at the voice coil position. By adopting the magnetic circuit structure described in the present embodiment, it can be seen that the magnetic flux density at the voice coil position is improved as compared with the conventional case.

  As described above, even if the electrodynamic electroacoustic transducer in the present embodiment is an electroacoustic transducer having the same thickness, an electroacoustic transducer with higher efficiency can be provided. In addition, even with the same efficiency, a smaller and thinner electroacoustic transducer can be provided. Furthermore, since the magnetization directions of the first magnetic pole 11 and the second magnetic pole 12 are the same, it is possible to magnetize after the electroacoustic transducer is assembled. As a result, it is advantageous in terms of manufacturing man-hours compared to the case where the two magnets are magnetized in opposite directions.

  In the above description, the electrodynamic electroacoustic transducer 1, the first magnetic pole 11, the second magnetic pole 12, and the diaphragm 15 as viewed from the vibration direction are circular, but are elliptical. May be.

  In the electrodynamic electroacoustic transducer 1 described above, the first magnetic pole 11 is formed in a columnar shape, but may be formed in a cylindrical columnar body. In other words, the first magnetic pole 11 may be constituted by a columnar body in which a through hole (hollow hole) coaxial with the columnar shape of the first magnetic pole 11 shown in FIG. 1 is formed. In other words, the first magnetic pole 11 may be formed of an annular body having a gap formed at the center thereof. Further, the lower surface of the second magnetic pole 12 may be arranged on the back side of the electrodynamic electroacoustic transducer 1 from the upper surface of the first magnetic pole 11. In FIG. 5, the shape of the first magnetic pole 11 is configured as a columnar shape having a coaxial through hole, and the second magnetic pole is formed on the back side of the electrodynamic electroacoustic transducer 1 from the upper surface of the first magnetic pole 11. 12 is a structural sectional view in which the lower surface of 12 is arranged. The second magnetic pole 12 is disposed such that a magnetic gap is formed between the first magnetic pole 11 and the second magnetic pole 12. At this time, as shown in FIG. 5, a sound hole having the same diameter as the through hole formed in the first magnetic pole portion 11 is formed in the yoke 13.

  The structure shown in FIG. 5 is a structure in which air between the upper surface of the first magnetic pole 11 and the lower surface of the diaphragm 15 is particularly easy to escape due to the through hole formed coaxially with the first magnetic pole 11. That is, there is an effect that the sound on the lower surface of the diaphragm 15 can be easily removed downward. In addition, the lower surface of the second magnetic pole 12 is disposed on the back side of the electrodynamic electroacoustic transducer 1 from the upper surface of the first magnetic pole 11. That is, the structure shown in FIG. 5 is a structure in which the magnet 11a and the magnet 12a can be made thicker than the structure shown in FIG. 1 when the thickness of the electrodynamic electroacoustic transducer itself is the same. This structure is advantageous in terms of high efficiency.

  In the electrodynamic electroacoustic transducer 1, the plate 11b of the first magnetic pole 11 may be omitted. FIG. 6 is a structural cross-sectional view in which the plate 11b is omitted in the electrodynamic electroacoustic transducer 1 described above. FIG. 7 is a perspective view of a part of the electrodynamic electroacoustic transducer 1 with the plate 11b omitted. In the electrodynamic electroacoustic transducer 1 shown in FIGS. 6 and 7, the operating point of the magnet 11a is lowered due to the omission of the plate 11b, but it is advantageous in terms of materials and man-hours in manufacturing. 6 and 7, the first magnetic pole 11 is composed of the magnet 11a, but may be composed of a magnetic material other than a magnet such as iron.

  In the electrodynamic electroacoustic transducer 1, the plate 12b of the second magnetic pole 12 may be omitted. FIG. 8 is a structural cross-sectional view in which the plate 12b is omitted from the electrodynamic electroacoustic transducer 1 described above. FIG. 9 is a perspective view of a part of the electrodynamic electroacoustic transducer 1 with the plate 12b omitted. In the electrodynamic electroacoustic transducer 1 shown in FIGS. 8 and 9, the operating point of the magnet 12a is lowered because the plate 12b is omitted, but it is advantageous in terms of materials and man-hours in manufacturing. 8 and 9, the second magnetic pole 12 is composed of the magnet 12a, but it may be composed of a magnetic material other than a magnet such as iron.

  Further, in the electrodynamic electroacoustic transducer 1, both the plate 11b of the first magnetic pole 11 and the plate 12b of the second magnetic pole 12 may be omitted. FIG. 10 is a structural cross-sectional view in which the plate 11b and the plate 12b are omitted from the electrodynamic electroacoustic transducer 1 described above. FIG. 11 is a perspective view of a part of the electrodynamic electroacoustic transducer 1 in which the plate 11b and the plate 12b are omitted. In the electrodynamic electroacoustic transducer 1 shown in FIG. 10 and FIG. 11, the operating points of the magnet 11a and the magnet 12a are lowered by omitting the plate 11b and the plate 12b. Is advantageous. 10 and 11, the first magnetic pole 11 is composed of a magnet 11a, and the second magnetic pole 12 is composed of a magnet 12a. However, one of the magnetic poles is made of a magnet other than a magnet such as iron. It may be composed of a body.

  As described above, according to the electrodynamic electroacoustic transducer according to the first embodiment, the inner peripheral shape of the second magnetic pole 12 is larger than the outer peripheral shape of the first magnetic pole 11, and the second magnetic pole 12 is The first magnetic pole 11 is located in an oblique front direction extending from the magnetic pole 11, and the first and second magnetic poles do not overlap with the vibration direction of the diaphragm. Then, by forming the diaphragm so as to be separated from the first and second magnetic poles by an amplitude margin, in the case of realizing an electrodynamic electroacoustic transducer having the same thickness as the conventional one, the magnet is compared with the conventional one. The thickness in the vibration direction can be increased. As a result, the magnetic flux density at the voice coil position is improved, and a highly efficient electrodynamic electroacoustic transducer can be realized with the same thickness as the conventional one.

  Further, according to the electrodynamic electroacoustic transducer according to the first embodiment, the inner peripheral shape of the voice coil is larger than the outer peripheral shape of the first magnetic pole, and the outer peripheral shape of the voice coil is the inner periphery of the second magnetic pole. The structure is smaller than the circumferential shape. Thus, since the first and second magnetic poles do not exist in the vibration direction of the voice coil, the thickness of the vibration direction of the magnet can be obtained by making the diaphragm away from the first and second magnetic poles by an amplitude margin. Can be made even thicker. That is, in the past, the magnet, yoke, and voice coil were configured to overlap in the diaphragm vibration direction, so the magnet thickness was limited, whereas the voice coil and magnet did not overlap in the thickness direction. By making the shape of the diaphragm difficult to contact the first and second magnetic poles during vibration of the diaphragm, the magnet can be made thicker. As a result, the magnetic flux density at the voice coil position is further improved, and an electroacoustic transducer with high efficiency can be realized even if it is thin. When the effect due to the shape of the voice coil is not expected, the inner peripheral shape of the voice coil is smaller than the outer peripheral shape of the first magnetic pole and / or the outer peripheral shape of the voice coil is the second magnetic pole. The structure may be larger than the inner peripheral shape.

  Furthermore, as magnets become thicker, magnets made from neodymium, which are generally used for small thin speakers, have increased permeance coefficients and are resistant to high temperature demagnetization. Therefore, it is possible to use a magnet having a higher energy product while improving the temperature reliability or maintaining the same temperature reliability. As a result, the magnetic flux density at the voice coil position can be further improved, and a more efficient small and thin electroacoustic transducer can be realized.

  Further, since the first magnetic pole and the second magnetic pole have the same polarity, even when both the first magnetic pole and the second magnetic pole are made of a magnetic material including a magnet, the electroacoustic transducer is used. Can be magnetized after assembling the two magnets, which is advantageous in manufacturing compared to the case where the two magnets are magnetized in opposite directions.

  In addition, the electrodynamic electroacoustic transducer according to the first embodiment is not an electromagnetic induction type using the driving primary coil 314 that causes a decrease in the magnetic flux density in the magnetic gap. When the thickness is the same, the magnetic flux density of the magnetic gap can be improved as compared with the electromagnetic induction type.

(Second Embodiment)
The electrodynamic electroacoustic transducer 2 according to the second embodiment of the present invention will be described with reference to FIGS. 12 and 13. FIG. 12 is a structural cross-sectional view of the electrodynamic electroacoustic transducer 2 according to the second embodiment. FIG. 13 is a perspective view of a part of the electrodynamic electroacoustic transducer 2 cut out. In FIG. 12, the electrodynamic electroacoustic transducer 2 includes a first magnetic pole 21, a second magnetic pole 22, a yoke 23, a voice coil 24, and a diaphragm 25. In addition, as shown in FIG. 13, the shape of the electrodynamic electroacoustic transducer 2 viewed from the vibration direction is a rectangle. The first magnetic pole 21 corresponds to the first magnetic pole part of the present invention, and the second magnetic pole 22 corresponds to the second magnetic pole part of the present invention.

  The first magnetic pole 21 includes a magnet 21a and a plate 21b fixed to the upper surface of the magnet 21a. The second magnetic pole 22 includes a magnet 22a and a plate 22b fixed to the lower surface of the magnet 22a. The plates 21b and 22b are magnetic bodies (for example, iron etc.) other than magnets. As shown in FIG. 13, the shape of the first magnetic pole 21 is a rectangular parallelepiped (columnar body), and the shape of the second magnetic pole 22 is an annular body in which a rectangular opening is formed at the center of the rectangular parallelepiped. Composed.

  Here, the second magnetic pole 22 is located on the front side of the electrodynamic electroacoustic transducer 2 with respect to the first magnetic pole 21. In addition, the first magnetic pole 21 and the second magnetic pole 22 are arranged so that their central axes coincide. Furthermore, the inner peripheral shape of the second magnetic pole 22 (the inner side length of the opening) is larger than the outer peripheral shape of the first magnetic pole 21 (the outer side length excluding the side parallel to the central axis). The lower surface of the second magnetic pole 22 is disposed at the same position as the upper surface of the first magnetic pole 21 or at least on the front side of the electrodynamic electroacoustic transducer 2 from the upper surface. In other words, the second magnetic pole 22 is positioned in the oblique front direction extending from the first magnetic pole 21 and is disposed so that a magnetic gap is formed between the first magnetic pole 21 and the second magnetic pole 22. . In addition, the magnetic gap between the 1st magnetic pole 21 and the 2nd magnetic pole 22 is formed so that it may become a uniform dimension over the perimeter, for example.

  The yoke 23 fixes the lower surface of the first magnetic pole 21 and the upper surface of the second magnetic pole 22 respectively, and supports the first magnetic pole 21 and the second magnetic pole 22 by magnetic coupling. Here, the lower surface of the first magnetic pole 21 and the upper surface of the second magnetic pole 22 correspond to one of the magnetic pole surfaces of the present invention. The voice coil 24 has a rectangular frame shape, is fixed to the diaphragm 25 and is held in the magnetic gap by the diaphragm 25. The inner peripheral shape (inner side) of the voice coil 24 is configured to be larger than the outer peripheral shape of the first magnetic pole 21 (outer side opposite to the inner side of the voice coil 24). The outer peripheral shape (outer side) of the voice coil 24 is configured to be smaller than the inner peripheral shape of the second magnetic pole 22 (inner side facing the outer side of the voice coil 24). That is, the difference between the inner peripheral shape (inner side) of the second magnetic pole 22 and the outer peripheral shape of the first magnetic pole 21 (outer side opposite to the inner side of the second magnetic pole 12) is larger than the frame width of the voice coil 24. Largely composed. The diaphragm 25 is disposed so that the outer periphery thereof is fixed to the yoke 23 and is located in a gap formed between the first magnetic pole 21, the second magnetic pole 22, and the yoke 23. Moreover, the shape of the diaphragm 25 viewed from the vibration direction is a rectangle. Further, the diaphragm 25 is formed with an edge portion 25a similar to the edge portion 15a of the diaphragm 15 described above.

  The magnet 21a and the magnet 22a are magnetized in the same polarity in the vibration direction of the diaphragm 25. Further, the yoke 23 is formed with a sound hole for radiating sound to the front side of the electrodynamic electroacoustic transducer 2 and a sound hole for pressure relief on the back side.

  The electrodynamic electroacoustic transducer 2 according to the second embodiment is different from the electrodynamic electroacoustic transducer 1 described in the first embodiment only in the shape, and the electrodynamic electroacoustic transducer Since the operation of the transducer 2 is the same as that of the electrodynamic electroacoustic transducer 1, detailed description thereof is omitted. Further, the electrodynamic electroacoustic transducer 2 according to the second embodiment can obtain the same effects as those of the first embodiment.

  Here, the outer shape of the electrodynamic electroacoustic transducer 2 viewed from the vibration direction, the first magnetic pole 21, the second magnetic pole 22, and the diaphragm 25 are rectangular. Generally, there are many rectangular spaces inside the housing of an electronic device. Therefore, since the shape of the electrodynamic electroacoustic transducer 2 viewed from the vibration direction is rectangular, the electrodynamic electroacoustic transducer 2 can be mounted without waste in the space inside the electronic device. That is, the electrodynamic electroacoustic transducer 2 has a higher space utilization rate in the same space than the circular electrodynamic electroacoustic transducer 1. Further, since the shape of the diaphragm 25 is rectangular, a large area of the diaphragm in the same space can be secured. That is, the efficiency can be improved as much as the area of the diaphragm 25 of the electrodynamic electroacoustic transducer 2 is secured.

  Note that, as in the first embodiment, at least one of the plates 21b and 22b of the electrodynamic electroacoustic transducer 2 may be omitted. Further, although the first magnetic pole 21 includes the magnet 21a and the second magnetic pole 22 includes the magnet 22a, the magnet of any one of the magnetic poles may be made of a magnetic material other than a magnet such as iron.

  The outer shape of the electrodynamic electroacoustic transducer 2 viewed from the vibration direction, the first magnetic pole 21, the second magnetic pole 22, and the diaphragm 25 are rectangular, but other polygonal shapes are used. May be. Moreover, the shape according to the shape inside an electronic component housing | casing and a use may be sufficient. For example, it may be an elongated rectangular shape in which two sides facing in parallel are extremely shorter than the other two sides. Further, for example, the shape may be a shape having rounded corners or sides of a polygonal shape or a part thereof.

  In the electrodynamic electroacoustic transducer 2 described above, the first magnetic pole 21 is formed of a rectangular parallelepiped, but may be a rectangular frame as shown in FIGS. In other words, the first magnetic pole 21 may be a columnar body in which a rectangular through hole (hollow hole) coaxial with the rectangular parallelepiped of the first magnetic pole 21 shown in FIGS. 12 and 13 is formed. Good. In other words, the first magnetic pole 21 may be formed of an annular body in which a rectangular gap is formed. FIG. 14 is a structural cross-sectional view of the electrodynamic electroacoustic transducer 2 showing a configuration in which the shape of the first magnetic pole 21 is a frame shape. FIG. 15 is a perspective view of a part of the electrodynamic electroacoustic transducer 2 showing a configuration in which the shape of the first magnetic pole 21 is a frame shape. The second magnetic pole 22 is disposed such that a magnetic gap is formed between the first magnetic pole 21 and the second magnetic pole 22. At this time, as shown in FIG. 14, the yoke 23 is formed with a sound hole having the same diameter as the through hole formed in the first magnetic pole portion 21. The structure shown in FIGS. 14 and 15 is a structure in which air between the upper surface of the first magnetic pole 21 and the lower surface of the diaphragm 25 is particularly easy to escape by a through hole formed coaxially with the first magnetic pole 21. It becomes. That is, the structure shown in FIG. 14 and FIG. 15 exhibits an effect that the sound on the lower surface of the diaphragm 15 can easily escape downward.

(Third embodiment)
An electrodynamic electroacoustic transducer 3 according to a third embodiment of the present invention will be described with reference to FIGS. 16 and 17. FIG. 16 is a structural sectional view of the electrodynamic electroacoustic transducer 3 according to the third embodiment. FIG. 17 is a perspective view of a part of the electrodynamic electroacoustic transducer 3 cut out. In FIG. 16, the electrodynamic electroacoustic transducer 3 includes a first magnetic pole 31, a second magnetic pole 32, a yoke 33, a voice coil 34, and a diaphragm 35. As shown in FIG. 17, the shape of the electrodynamic electroacoustic transducer 3 as viewed from the vibration direction is a shape like a race track in which only two opposite sides of a rectangle are formed in a semicircle (hereinafter referred to as a track). It is described as a shape). The first magnetic pole 31 corresponds to the first magnetic pole part of the present invention, and the second magnetic pole 32 corresponds to the second magnetic pole part of the present invention.

  The first magnetic pole 31 includes a magnet 31a and a plate 31b fixed to the upper surface of the magnet 31a. The second magnetic pole 32 includes a magnet 32a and a plate 32b fixed to the lower surface of the magnet 32a, and a plate 32d fixed to the lower surface of the magnet 32c and the magnet 32c. The plates 31b, 32b, and 32d are magnetic bodies (for example, iron) other than magnets. In addition, as shown in FIG. 17, the shape of the 1st magnetic pole 31 is a rectangular parallelepiped (columnar body). The shape of the second magnetic pole 32 is two rectangular parallelepipeds (a magnet 32a, a plate 32b, a magnet 32c, and a magnet obtained by removing a curved frame portion from an annular body in which a rectangular opening is formed at the center of a track-shaped columnar body. Plate 32d).

  Here, the second magnetic pole 32 is located on the front side of the electrodynamic electroacoustic transducer 3 with respect to the first magnetic pole 31. Further, the two rectangular parallelepipeds constituting the second magnetic pole 32 are respectively arranged at positions facing the long sides of the first magnetic pole 31. In other words, the track-shaped annular body constituting the second magnetic pole 32 and the first magnetic pole 31 are arranged so that the central axes thereof coincide with each other. Further, the inner peripheral shape (short inner side of the opening) of the annular body of the second magnetic pole 32 is larger than the outer peripheral shape of the first magnetic pole 31 (short outer side facing the short inner side of the second magnetic pole 32). large. The lower surface of the second magnetic pole 32 is disposed at the same position as the upper surface of the first magnetic pole 31 or at least on the front surface side of the electrodynamic electroacoustic transducer 3 from the upper surface. In other words, the two rectangular parallelepipeds constituting the second magnetic pole 32 are respectively positioned in the oblique front direction extending from the first magnetic pole 31, and the two rectangular parallelepipeds constituting the first magnetic pole 31 and the second magnetic pole 32 are It arrange | positions so that a magnetic gap may be formed among them. In addition, the magnetic gap between the 1st magnetic pole 31 and the 2nd magnetic pole 32 may be formed so that it may become a uniform dimension over the space which each opposes, for example.

  The yoke 33 fixes the lower surface of the first magnetic pole 31 and the upper surface of the second magnetic pole 32, and supports the first magnetic pole 31 and the second magnetic pole 32 by magnetically coupling them. Here, the lower surface of the first magnetic pole 31 and the upper surface of the second magnetic pole 32 respectively correspond to one magnetic pole surface of the present invention. The voice coil 34 has a rectangular frame shape, is fixed to the diaphragm 35, and two sides thereof are held in the magnetic gap. The inner peripheral shape (inner side) of the voice coil 34 is configured to be larger than the outer peripheral shape of the first magnetic pole 31 (outer side opposite to the inner side of the voice coil 34). The outer peripheral shape (two short outer sides of the outer sides) of the voice coil 34 is smaller than the inner peripheral shape of the annular body of the second magnetic pole 32 (short inner side facing the short outer side of the voice coil 34). Composed. That is, the difference between the inner peripheral shape (short inner side) of the second magnetic pole 32 and the outer peripheral shape of the first magnetic pole 31 (short outer side facing the short inner side of the second magnetic pole 32) is the voice coil 34. It is configured to be larger than the frame width. That is, the structure of this embodiment is a structure in which the voice coil 34 does not contact the first magnetic pole 31 and the second magnetic pole 32 in the vibration direction, as shown in FIG. The diaphragm 35 is disposed so that the outer periphery thereof is fixed to the yoke 33 and is located in a gap formed between the first magnetic pole 31, the second magnetic pole 32, and the yoke 33. Moreover, the shape of the diaphragm 35 viewed from the vibration direction is a track shape. Further, the diaphragm 35 is formed with an edge portion 35a similar to the edge portion 15a of the diaphragm 15 described above.

  The magnet 31a, the magnet 32a, and the magnet 32c are magnetized to the same polarity in the vibration direction of the diaphragm 35. In addition, the yoke 33 is formed with a sound hole for emitting sound to the front side of the electrodynamic electroacoustic transducer 3 and a sound hole for exhausting pressure on the back side.

  The electrodynamic electroacoustic transducer 3 according to the third embodiment is different from the electrodynamic electroacoustic transducer 1 described in the first embodiment only in shape, and the electrodynamic electroacoustic transducer 1 Since the operation of the transducer 3 is the same as that of the electrodynamic electroacoustic transducer 1, detailed description thereof is omitted. Further, the electrodynamic electroacoustic transducer 3 according to the third embodiment can obtain the same effects as those of the first embodiment.

  Here, the outer shape and the shape of the diaphragm 35 viewed from the vibration direction of the electrodynamic electroacoustic transducer 3 according to the present embodiment are track shapes. That is, since the electrodynamic electroacoustic transducer 3 and the diaphragm 35 are not circular, the space utilization efficiency is increased as in the second embodiment. Further, in the rectangle described in the second embodiment, the stiffness of the edge becomes high at the corner portion, whereas in the third embodiment, the overall stiffness can be improved by configuring with a curve. . Therefore, in the third embodiment, the electroacoustic transducer with less distortion in the low sound range is realized by facilitating the vibration of the corner portion as compared with the rectangular diaphragm.

  As in the first embodiment, at least one of the plate 31b, the plate 32b, and the plate 32d of the electrodynamic electroacoustic transducer 3 may be omitted. In addition, the first magnetic pole 31 includes the magnet 31a and the second magnetic pole 32 includes the magnets 32a and 32c, but the magnet of either one of the magnetic poles may be formed of a magnetic material other than a magnet such as iron. Good.

  Further, although the first magnetic pole 31 described above is configured by one rectangular parallelepiped, as shown in FIGS. 18 and 19, the first magnetic pole 31 has two rectangular parallelepipeds so as to provide a space in the center thereof ( A magnet 31a, a plate 31b, a magnet 31c, and a plate 31d) may be used. In other words, the first magnetic pole 31 formed of the columnar body shown in FIGS. 16 and 17 is a straight line in the same direction as the long side in the direction perpendicular to the vibration direction and the central axis of the vibration direction is You may form the through-hole which makes the straight line made into the intersection a centerline. FIG. 18 is a structural cross-sectional view of the electrodynamic electroacoustic transducer 3 when the first magnetic pole 31 is composed of two rectangular parallelepipeds (two columnar bodies). FIG. 19 is a perspective view in which a part of the electrodynamic electroacoustic transducer 3 is cut off when the first magnetic pole 31 is composed of two rectangular parallelepipeds (two columnar bodies). At this time, as shown in FIG. 18, a sound hole having the same outer diameter as the through hole formed between the two rectangular parallelepipeds in the first magnetic pole portion 31 is formed in the yoke 33. By constituting the first magnetic pole 31 with two rectangular parallelepipeds, the air between the upper surface of the first magnetic pole 31 and the lower surface of the diaphragm 35 is particularly easy to escape. That is, there is an effect that the sound on the lower surface of the diaphragm 35 can easily escape downward.

(Fourth embodiment)
An electrodynamic electroacoustic transducer 4 according to a fourth embodiment of the present invention will be described with reference to FIGS. 20 is a plan view of the electrodynamic electroacoustic transducer 4 according to the fourth embodiment, and FIG. 21 is a cross-sectional view of the structure of the electrodynamic electroacoustic transducer 4 according to the fourth embodiment. In FIG. 20, the shape of the electrodynamic electroacoustic transducer 4 is circular. In FIG. 21, the electrodynamic electroacoustic transducer 4 includes a first magnet 41, a second magnet 42, a yoke 43, a voice coil 44, and a diaphragm 45. Further, a magnetic gap 47 is formed by the first magnet 41 and the second magnet 42. The first magnet 41 has a cylindrical shape. The second magnet 42 is a donut-shaped annular body. The first magnet 41 corresponds to the first magnetic pole part of the present invention, and the second magnet 42 corresponds to the second magnetic pole part of the present invention.

  Here, the second magnet 42 is located on the front side of the electrodynamic electroacoustic transducer 4 with respect to the first magnet 41. Further, the first magnet 41 and the second magnet 42 are arranged so that their central axes coincide. Further, the inner diameter of the second magnet 42 is larger than the outer diameter of the first magnet 41. The yoke 43 fixes the lower surface of the first magnet 41 and the magnetic pole surface on the outer peripheral side of the second magnet 42, and supports the first magnet 41 and the second magnet 42 by magnetically coupling them. . The voice coil 44 has an annular shape as shown in FIG. 19, is fixed to the diaphragm 45, and is held in the magnetic gap 47 by the diaphragm 45. Further, the inner diameter of the voice coil 44 is configured to be larger than the outer diameter of the first magnet 41. The outer diameter of the voice coil 44 is configured to be smaller than the inner diameter of the second magnet 42. The diaphragm 45 is disposed so that the outer periphery thereof is fixed to the yoke 43 and located in a gap formed between the first magnet 41, the second magnet 42, and the yoke 43. Moreover, the shape of the diaphragm 45 viewed from the vibration direction is circular. Further, the diaphragm 45 is formed with an edge portion 45a similar to the edge portion 15a of the diaphragm 15 described above. Due to the shape and positional relationship between the voice coil 44 and the first magnet 41 and the second magnet 42, the voice coil 44 and the first magnet 41 or the second magnet 42 even if the diaphragm 45 vibrates greatly. To prevent contact.

  Here, as shown in FIG. 21, the voice coil 44 is fixed so that the central portion of the diaphragm 45 has a convex shape with respect to the outer peripheral portion. Specifically, the central portion of the diaphragm 45 located inside the inner peripheral shape of the voice coil 44 forms a convex shape. Further, the outer peripheral portion of the diaphragm 45 that is outside the outer peripheral shape of the voice coil 44 forms a concave shape. Due to the shape of the vibration plate 45, the vibration plate 45 and the first magnet 41 and the second magnet 42 are in a shape that is most difficult to come into contact with each other by vibration. Even if it comprises, the 1st magnet 41 and the 2nd magnet 42 can be made thick, ensuring the same amplitude margin.

  The first magnet 41 is magnetized in the vibration direction of the diaphragm 45, and the second magnet 42 is magnetized in the circumferential direction (perpendicular to the vibration direction). In addition, the yoke 43 is formed with a sound hole for emitting sound to the front side of the electrodynamic electroacoustic transducer 4 and a sound hole for exhausting pressure on the back side. Hereinafter, the operation of the electrodynamic electroacoustic transducer 4 will be described.

  As described above, the magnetic gap 47 is formed between the first magnet 41 and the second magnet 42. When a signal current flows through the voice coil 44 located in the magnetic gap 47, a driving force proportional to the product of the magnitude of the current and the magnetic flux density at the voice coil position is generated. Then, the diaphragm 45 vibrates by the driving force, so that sound is emitted.

  As in the first embodiment, the electrodynamic electroacoustic transducer 4 in the fourth embodiment is configured such that the inner diameter of the second magnet 42 is larger than the outer diameter of the first magnet 41, and the voice coil 44. Is larger than the outer periphery of the first magnet 41, and the outer periphery of the voice coil 44 is smaller than the inner periphery of the second magnet 42. The first magnet 41 or the second magnet 42 does not contact. The diaphragm 45 is disposed in a shape and a position where it is difficult to contact the first magnet 41 and the second magnet 42 by vibration. Furthermore, in the fourth embodiment, since the magnetization direction of the second magnet 42 is the circumferential direction, in the first embodiment, the yoke 13 fixed on the upper surface of the second magnetic pole 12 is connected to the second magnet 42. Is fixed to the magnetic pole surface on the outer peripheral side. As a result, it is possible to further reduce the thickness by the thickness of the yoke. When the electrodynamic electroacoustic transducer is configured with the same thickness as that of the first embodiment, the thickness of the second magnet 42 can be increased. Further, by increasing the thickness of the second magnet 42, the magnetic flux density is increased, and even when a high energy product magnet using neodymium or the like is used, the permeance coefficient is increased and it is strong against high temperature demagnetization.

  Here, with reference to FIG. 22, the flow of the magnetic flux which the 1st magnet 41 and the 2nd magnet 42 in 4th Embodiment comprise is demonstrated. FIG. 22 is a diagram illustrating a magnetic flux vector obtained by analyzing a magnetic field by an example of a finite element method in the magnetic circuit according to the fourth embodiment. In FIG. 22, it can be seen that a magnetic flux having a direction component perpendicular to the vibration direction is formed on the voice coil 44. In this manner, the first magnet 41 is magnetized in the vibration direction and the second magnet 42 is magnetized in the circumferential direction, thereby forming a driving magnetic flux having a direction component perpendicular to the vibration direction.

  In the fourth embodiment, the shapes of the first magnet 41, the second magnet 42, and the diaphragm 45 are circular, but may be elliptical. As a result, an electroacoustic transducer having a shape suitable for the equipment to be mounted can be realized.

  Further, although the lower surface of the second magnet 42 is located in the front direction rather than the upper surface of the first magnet 41, even if the first magnet 41 is located in the front direction on the same plane. Good.

  Further, as shown in FIG. 23, a first plate 48 may be provided on the upper surface of the first magnet 41, and a second plate 49 may be provided on the magnetic pole surface on the inner peripheral side of the second magnet 42. FIG. 23 is a structural cross-sectional view in the case where the plates 48 and 49 are added and the first magnet 41 has a through hole in the electrodynamic electroacoustic transducer 4 shown in FIG. The plates 48 and 49 are magnetic bodies (for example, iron) other than magnets. In the electrodynamic electroacoustic transducer 4 shown in FIG. 23, the magnetic flux can be concentrated by providing the plate, and the voice coil can be provided at a more optimal position. In FIG. 23, both the first magnet 41 and the second magnet 42 are provided with plates, but the plate may be provided only on one of the magnets depending on the target thickness and efficiency of the electroacoustic transducer.

  In the fourth embodiment, a columnar magnet is used for the first magnet 41. However, as shown in FIG. 23, a cylindrical shape having a through hole at the center may be used. That is, it may be an annular magnet having a gap formed in the center. By similarly providing a through hole at the same position of the yoke below the first magnet 41, it becomes easier to remove the air below the diaphragm.

(Fifth embodiment)
With reference to FIGS. 24 and 25, an electrodynamic electroacoustic transducer 5 according to a fifth embodiment of the present invention will be described. 24 is a plan view of the electrodynamic electroacoustic transducer 5 according to the fifth embodiment, and FIG. 25 is a structural sectional view of the electrodynamic electroacoustic transducer 5 according to the fifth embodiment. In FIG. 25, the electrodynamic electroacoustic transducer 5 includes a first magnet 51, a second magnet 52, a yoke 53, a voice coil 54, and a diaphragm 55. In addition, as shown in FIG. 24, the shape of the electrodynamic electroacoustic transducer 5 seen from the vibration direction is a rectangle. In addition, the first magnet 51 is configured by a rectangular parallelepiped (columnar) magnet, and the second magnet 52 is configured by two rectangular parallelepiped magnets. The first magnet 51 corresponds to the first magnetic pole part of the present invention, and the second magnet 52 corresponds to the second magnetic pole part of the present invention.

  Here, as shown in FIG. 25, the second magnet 52 is located on the front side of the electrodynamic electroacoustic transducer 5 with respect to the first magnet 51. Further, the second magnet 52 is disposed opposite to the long side of the first magnet 51 at a symmetrical position with respect to the central axis of the first magnet 51. The lower surface of the second magnet 52 is disposed at the same position as the upper surface of the first magnet 51 or on the front surface side of the electrodynamic electroacoustic transducer 5 from the upper surface. The magnetic gap 57 between the first magnet 51 and the second magnet 52 is formed to have a uniform dimension along the long side portion of the first magnet 51.

  The yoke 53 has a lower surface of the first magnet 51 and a magnetic pole surface on the outer diameter side of the second magnet 52, and supports the first magnet 51 and the second magnet 52 by magnetically coupling them. To do. The voice coil 54 has a rectangular frame shape as shown in FIG. 24, is fixed to the diaphragm 55, and is held in the magnetic gap 57 by the diaphragm 55. The inner peripheral shape (inner side) of the voice coil 54 is configured to be larger than the outer peripheral shape of the first magnet 51 (outer side facing the inner side of the voice coil 54). The outer peripheral shape (outer side) of the voice coil 54 is configured to be smaller than the inner peripheral shape of the second magnet 52 (inner side facing the outer side of the voice coil 54). That is, the structure of the present embodiment is a structure in which the voice coil 54 does not contact the first magnet 51 and the second magnet 52 in the vibration direction, as shown in FIG. The diaphragm 55 is disposed so that the outer periphery thereof is fixed to the yoke 53 and located in a gap formed between the first magnet 51, the second magnet 52, and the yoke 53. Moreover, the shape of the diaphragm 55 viewed from the vibration direction is a rectangle. Further, the diaphragm 55 is formed with an edge portion 55a similar to the edge portion 15a of the diaphragm 15 described above.

  The first magnet 51 is magnetized in the vibration direction, and the second magnet 52 is magnetized in the direction perpendicular to the vibration direction (outer peripheral direction). The yoke 53 is formed with a sound hole for radiating sound to the front side of the electrodynamic electroacoustic transducer 5 and a sound hole for exhausting pressure on the back side.

  Note that the electrodynamic electroacoustic transducer 5 according to the fifth embodiment is different from the electrodynamic electroacoustic transducer 4 described in the fourth embodiment only in shape, and the electrodynamic electroacoustic transducer Since the operation of the transducer 5 is the same as that of the electrodynamic electroacoustic transducer 4, detailed description thereof is omitted. The electrodynamic electroacoustic transducer 5 according to the fifth embodiment can obtain the same effects as those of the fourth embodiment.

  Here, the outer shape of the electrodynamic electroacoustic transducer 5 viewed from the vibration direction, and the shapes of the first magnet 51, the second magnet 52, and the diaphragm 55 are rectangular. Generally, there are many rectangular spaces inside the housing of an electronic device. Therefore, since the shape of the electrodynamic electroacoustic transducer 5 viewed from the vibration direction is a rectangle, it can be mounted without waste in the space inside the electronic device. That is, the electrodynamic electroacoustic transducer 5 has a higher space utilization rate in the same space than the circular electrodynamic electroacoustic transducer 4. Moreover, since the shape of the diaphragm 55 is also rectangular, a large effective area can be secured. That is, the electrodynamic electroacoustic transducer 5 can improve the efficiency by the amount that the effective area of the diaphragm 55 is large.

  Further, as in the fourth embodiment, the lower surface of the second magnet 52 is positioned in the front direction rather than the upper surface of the first magnet 51. May be located in the front direction.

  Further, similarly to the fourth embodiment, a first plate may be provided on the upper surface of the first magnet 51, and a second plate may be provided on the magnetic pole surface on the inner peripheral side of the second magnet 52. By providing the plate, the magnetic flux can be concentrated and the voice coil can be provided at a more optimal position. In that case, a plate may be provided only on one of the magnets depending on the thickness and efficiency of the target electroacoustic transducer.

  In addition, although one cuboid-shaped magnet is used for the first magnet 51, it may be configured by two cuboid-shaped magnets so as to provide a space in the center. By providing the through hole at the same position of the yoke below the first magnet 51, it becomes easy to remove the air below the diaphragm.

  Moreover, although the 2nd magnet 52 was comprised with the magnet of two rectangular parallelepiped shape, you may comprise with one annular body magnet. For example, it has an annular shape like a magnet 22a shown in FIG. In this case, since the driving force is generated on the voice coil in the minor axis direction as in the major axis direction, the efficiency can be improved.

  Further, in the second magnet 52, two magnets may be further provided at a position facing the voice coil in the minor axis direction, and a substantially annular magnet may be configured by four magnets. In this case as well, the driving force is generated on the voice coil in the minor axis direction as in the major axis side, so that the efficiency is improved. Thus, by comprising the 2nd magnet 52 by multiple pieces, it becomes possible to implement | achieve the magnet shape which is hard to magnetize.

  Further, although the outer shape of the electrodynamic electroacoustic transducer 5 viewed from the vibration direction, the first magnet 51, the second magnet 52, and the diaphragm 55 are rectangular, other polygonal shapes are used. May be. Moreover, the shape according to the shape inside an electronic component housing | casing and a use may be sufficient. For example, it may be an elongated rectangular shape in which two sides facing in parallel are extremely shorter than the other two sides. Further, for example, the shape may be a shape having rounded corners or sides of a polygonal shape or a part thereof.

(Sixth embodiment)
With reference to FIGS. 26 to 29, an electrodynamic electroacoustic transducer 6 according to a sixth embodiment of the present invention will be described. 26 is a plan view of the electrodynamic electroacoustic transducer 6 according to the sixth embodiment, FIG. 27 is a structural sectional view, and FIG. 28 is a quarter of the first magnet, the second magnet, and the yoke. FIG. 29 is a perspective view of a vibration plate. In FIG. 27, the electrodynamic electroacoustic transducer 6 includes a first magnet 61, a second magnet 62, a yoke 63, a voice coil 64, and a diaphragm 65. As shown in FIG. 26, the shape of the electrodynamic electroacoustic transducer 6 viewed from the vibration direction is a track shape. The first magnet 61 corresponds to the first magnetic pole part of the present invention, and the second magnet 62 corresponds to the second magnetic pole part of the present invention.

  The magnetic circuit structure of the sixth embodiment is the same as that of the fifth embodiment with respect to the first magnet 61, the second magnet 62, and the voice coil 64, and the first magnet 61 has a rectangular parallelepiped shape, The magnet 62 is composed of two rectangular magnets having a shape obtained by removing a curved frame portion from an annular body in which a rectangular opening is formed at the center of a track-shaped columnar body. Further, the voice coil 64 has a rectangular shape and is fixed to the diaphragm 65 and held in the magnetic gap 67. Further, the inner peripheral shape of the voice coil 64 is configured to be larger than the outer peripheral shape of the first magnet 61, and the outer peripheral shape of the voice coil 64 may be configured to be smaller than the inner peripheral shape of the second magnet 62. It is the same. Similarly, the magnetization directions of the first magnet 61 and the second magnet 62 are the vibration direction and the direction perpendicular to the vibration direction, respectively.

  The yoke 63 and the diaphragm 65 are different from the fifth embodiment described above. The outer shape of the yoke 63 and the diaphragm 65 is a track shape. Further, as shown in FIGS. 27 and 28, the yoke 63 is cut out at the outer peripheral side of the long side portion of the first magnet 61 and the portion facing the second magnet 62. That is, the yoke 63 has an opening 63 h at a portion facing the second magnet 62. The opening 63 h is formed in a size including at least a portion facing the second magnet 62. The yoke 63 magnetically couples and supports the lower surface of the first magnet 61 and the magnetic pole surface on the outer peripheral side of the second magnet 62 as in the fifth embodiment described above. However, as shown in FIG. 28, the magnetic flux flowing through the opening 63h in the fifth embodiment flows through the yoke 63 at the portion indicated by the arrow in the sixth embodiment. Thus, the magnetic path is different between the sixth embodiment and the fifth embodiment. Further, as shown in FIG. 29, the diaphragm 65 has an edge portion, which is an outer peripheral side portion from the voice coil 64, formed in accordance with the shape of the yoke 63. That is, the edge portion 65a in which the yoke 63 does not exist on the lower surface of the edge portion forms a concave shape (a convex shape on the opening 63h side) when viewed from the upper surface. The edge portion 65b in which the yoke 63 is present on the lower surface of the edge forms a convex shape when viewed from the upper surface (concave shape on the yoke 63 side on the lower surface of the edge). The edge portions 65a and 65b may be configured integrally with the diaphragm 65 other than the edge portions 65a and 65b, or may be configured separately.

  The electrodynamic electroacoustic transducer 6 according to the sixth embodiment is different from the electrodynamic electroacoustic transducer 4 described in the fourth embodiment only in the shape of each component. Since the operation of the electric type electroacoustic transducer 6 is the same as that of the electrodynamic type electroacoustic transducer 4, a detailed description thereof will be omitted. Moreover, the electrodynamic electroacoustic transducer 6 according to the sixth embodiment can obtain the same effects as those of the fourth embodiment.

  Here, the outer shape and the shape of the diaphragm 65 viewed from the vibration direction of the electrodynamic electroacoustic transducer 6 according to the present embodiment are track shapes. That is, since the electrodynamic electroacoustic transducer 6 and the diaphragm 65 are not circular, the space utilization efficiency increases as in the fifth embodiment. Further, in the rectangle described in the fifth embodiment, the stiffness of the edge becomes high at the corner portion, whereas in the sixth embodiment, the overall stiffness can be improved by forming the curve. . Therefore, in the sixth embodiment, the electroacoustic transducer with less distortion in the low sound range is realized by facilitating the vibration of the corner portion as compared with the rectangular diaphragm.

  Furthermore, in the sixth embodiment, a portion of the yoke 63 that faces the second magnet 62 is cut out, and a portion of the yoke 63 that does not have the facing second magnet 62 is not cut out and becomes a part of the magnetic path. Yes. Correspondingly, the edge on the short diameter side of the diaphragm 65 has a concave shape in the vibration direction, and the edge on the long diameter side has a convex shape so as not to contact the second magnet 62 and the yoke 63, respectively. As a result, since the second magnet 62 can be provided downward by the thickness of the yoke 63, the distance between the first magnet 61 and the second magnet 62 is reduced, and the magnetic flux density generated in the magnetic gap 67 is reduced. growing. Therefore, a highly efficient electroacoustic transducer can be achieved even if it is thin.

  In the sixth embodiment, the upper surface of the first magnet 61 and the lower surface of the second magnet 62 are located on the same plane, but one may be provided so as to be located in the front direction. .

  Further, similarly to the fourth embodiment, a first plate may be provided on the upper surface of the first magnet 61 and a second plate may be provided on the magnetic pole surface on the inner peripheral side of the second magnet 62. By providing the plate, the magnetic flux can be concentrated and the voice coil can be provided at a more optimal position. In that case, a plate may be provided only on one of the magnets depending on the thickness and efficiency of the target electroacoustic transducer.

  In addition, although one cuboid-shaped magnet is used for the first magnet 61, it may be composed of two cuboid-shaped magnets so as to provide a space in the center. Providing a through hole at the same position of the yoke 63 below the first magnet 61 makes it easier to vent air below the diaphragm.

  Moreover, although the shape of the voice coil is a rectangular shape, it may be a track shape like the diaphragm shape.

(Seventh embodiment)
With reference to FIGS. 30 to 32, an electrodynamic electroacoustic transducer 7 according to a seventh embodiment of the present invention will be described. FIG. 30 is a structural cross-sectional view of the electrodynamic electroacoustic transducer 7 according to the seventh embodiment. 31 and 32 will be described later. 30, the electrodynamic electroacoustic transducer 7 includes a first magnetic pole 11, a second magnetic pole 12, a yoke 73, a voice coil 14, and a diaphragm 15. Here, the first magnetic pole 11, the second magnetic pole 12, the voice coil 14, and the diaphragm 15 are the same as the respective components of the first embodiment described above, and the same reference numerals are given and description thereof is omitted. To do.

  As shown in FIG. 30, the electrodynamic electroacoustic transducer 7 is a transducer having a yoke structure different from that of the electrodynamic electroacoustic transducer 1 described above. Specifically, the yoke 73 has a structure projecting inward from the inner diameter of the second magnetic pole 12 in the portion where the second magnetic pole 12 is fixed. That is, the sound hole formed on the front surface side of the electrodynamic electroacoustic transducer 7 becomes a sound hole having an inner diameter smaller than that of the first embodiment by the yoke 73. However, such a structure can be taken when the thickness of the second magnetic pole 12 is sufficiently thick and the diaphragm 15 contacts the second magnetic pole 12 before contacting the protruding portion of the yoke 73. It is.

  The flow of magnetic flux between the first magnetic pole 11 and the second magnetic pole 12 is as shown by the arrows in FIG. FIG. 31 is a diagram in which an example of a magnetic circuit according to the present embodiment is subjected to magnetic field analysis by a finite element method, and the flow of magnetic flux is represented by a vector. Further, when the magnetic flux density at the voice coil position is compared between the electrodynamic electroacoustic transducer 1 and the electrodynamic electroacoustic transducer 7, it is as shown in FIG. FIG. 32 is a diagram showing the magnetic flux densities at the respective voice coil positions of the electrodynamic electroacoustic transducer 1 and the electrodynamic electroacoustic transducer 7 by curves. That is, FIG. 32 shows the case where the yoke is overhanging (electrokinetic electroacoustic transducer 7 using the yoke 73) and the case where there is no yoke overhanging (electrokinetic electroacoustic transducer 1 using the yoke 13). It is the figure which compared the magnetic flux density in a voice coil position.

  As shown in FIG. 32, when there is an overhang, the magnetic flux density at the voice coil position increases, and a greater driving force can be obtained than when there is no overhang. That is, the structure of the electrodynamic electroacoustic transducer 7 can obtain a larger driving force than the structure of the electrodynamic electroacoustic transducer 1.

  In addition, by providing a protruding portion of the yoke 73, a magnetic circuit including the first magnetic pole 11 and the yoke 73 of the portion to which the first magnetic pole 11 is fixed, the second magnetic pole 12, and the second magnetic pole 11 are provided. The magnetic circuit constituted by the yoke 73 of the portion to which the magnetic pole 12 is fixed has a configuration close to vertical symmetry with the voice coil 14 as a reference. As a result, as shown in FIG. 32, the magnetic flux density curve when there is an overhang is a curve that is closer to line symmetry with respect to the axis of amplitude 0 than the curve when there is no overhang. As a result, the electrodynamic electroacoustic transducer 7 can reduce the distortion of the reproduced sound more than the electrodynamic electroacoustic transducer 1.

  The diaphragms (15, 25, 35, 45, 55, and 65) in the first to seventh embodiments described above have the diaphragm and voice coils (14, 24, 34, 44, 54, and 64). ), For example, a shape as shown in FIGS. Specifically, the shape of the diaphragm is such that the portion facing the upper surface of the first magnetic pole is above the lower end of the voice coil, and the portion facing the lower surface of the second magnetic pole is below the upper end of the voice coil. It becomes a shape. FIG. 33 is a diagram illustrating an example of the shape of the diaphragm in the fixed portion between the diaphragm and the voice coil. FIG. 34 is a diagram illustrating another example of the shape of the diaphragm in the fixed portion between the diaphragm and the voice coil. In FIG. 33, the voice coil 14 is fixed to the diaphragm 15 so that the lower surface of the voice coil 14 is disposed on the upper surface of the diaphragm 15. In FIG. 34, the voice coil 14 is fixed to the diaphragm 15 so that the upper surface of the voice coil 14 is disposed on the lower surface of the diaphragm 15.

  In addition, although the diaphragm (15, 25, 35, 45, 55, and 65) in the first to seventh embodiments described above is fixed to the yoke, it is not limited to this. For example, as shown in FIG. 35, a structure in which a support 131 is fixed to the yoke 13 and the outer periphery of the diaphragm 15 is fixed to the support 131 may be employed. FIG. 35 is a diagram illustrating an example in which the outer periphery of the diaphragm 15 is fixed to the support 131. The support may be made of a magnetic material or a non-magnetic material.

  The electrodynamic electroacoustic transducers according to the first to seventh embodiments described above can be realized by being mounted on an electronic device such as a mobile device, an AV device, or a video device. Examples of the mobile device include a mobile phone, a PDA (Personal Digital Assistant), a personal computer, and a portable music player. Examples of the AV device include devices such as a television, an audio, and a car audio. Examples of the video equipment include a television such as a plasma display panel (PDP), a liquid crystal, or a cathode ray tube. Hereinafter, a specific example in which the electrodynamic electroacoustic transducer according to the present invention is mounted on a thin TV such as a mobile phone or a PDP will be described. Further, a specific example in which the electrodynamic electroacoustic transducer according to the present invention is mounted on a car door as a car audio will be described.

  First, an example in which the electrodynamic electroacoustic transducer according to the present invention is fixed inside the housing of the mobile phone 80 will be described with reference to FIG. FIG. 36 is a front view and a side view showing an example of the electrodynamic electroacoustic transducer 1 mounted on the mobile phone 80. In FIG. 36, for example, it is assumed that the above-described electrodynamic electroacoustic transducer 1 is fixed inside the casing of the mobile phone 80. The electrodynamic electroacoustic transducer 1 is fixed to the left and right inside the housing at the lower part of the liquid crystal screen of the mobile phone 80.

  Here, in recent years, mobile devices such as mobile phones are required to be thinner and smaller. At the same time, the electrodynamic electroacoustic transducer mounted inside the housing is also required to be thin and small. On the other hand, as described above, the electrodynamic electroacoustic transducer 1 according to the present invention is thicker than the conventional electrodynamic electroacoustic transducer when the same amplitude margin as that of the conventional electromechanical transducer is secured. Can be made thin. As a result, according to the electrodynamic electroacoustic transducer of the present invention, it is possible to provide an electrodynamic electroacoustic transducer that is optimal for mounting on a mobile device such as a mobile phone.

  Next, with reference to FIG. 37, an example will be described in which the electrodynamic electroacoustic transducer according to the present invention is fixed inside the housing of a thin television 81 such as a PDP that is becoming thinner. FIG. 37 is a front view showing an example of the electrodynamic electroacoustic transducer 3 mounted on the flat-screen television 81 and a side view showing a part of the internal structure of the flat-screen television 81 in the OA section. In FIG. 37, for example, it is assumed that the above-described electrodynamic electroacoustic transducer 3 is fixed inside the casing of the thin television 81. The electrodynamic electroacoustic transducer 3 is fixed to the left and right inside the housing of the flat-screen television 81.

  Here, in recent years, video devices such as the thin television 81 are required to be thin. At the same time, the electrodynamic electroacoustic transducer mounted in the housing is also required to be thin. On the other hand, as described above, the electrodynamic electroacoustic transducer 3 according to the present invention is thicker than the conventional electrodynamic electroacoustic transducer when the same amplitude margin as that of the conventional electrodynamic transducer is secured. Can be made thin. As a result, according to the electrodynamic electroacoustic transducer according to the present invention, it is possible to provide an electrodynamic electroacoustic transducer that is optimal for mounting on video equipment such as the flat-screen television 81.

  Next, with reference to FIG. 38, an example in which the electrodynamic electroacoustic transducer according to the present invention is fixed to the main body 84 of the door 82 of the automobile will be described. FIG. 38 is a diagram illustrating an example of the electrodynamic electroacoustic transducer 1 mounted on the door 82 of the automobile. In FIG. 38, the door 82 of the automobile includes a window portion 83 and a main body portion 84. For example, it is assumed that the electrodynamic electroacoustic transducer 1 described above is fixed to the main body 84. The main body 84 is a housing having an internal space.

  Here, in the internal space of the main body 84 of the door 82, the space for installing the electrodynamic electroacoustic transducer is a very narrow space. However, as described above, the electrodynamic electroacoustic transducer 1 according to the present invention is thinner in thickness than the conventional electrodynamic electroacoustic transducer when the same amplitude margin as that of the conventional electromechanical electroacoustic transducer is secured. Can be configured. As a result, the electrodynamic electroacoustic transducer according to the present invention can provide an electrodynamic electroacoustic transducer that is optimal for mounting on the door 82 of the automobile.

  Furthermore, since automobiles are placed in various environments, extremely high temperature reliability is required for electronic devices mounted on the automobiles. On the other hand, when the electrodynamic electroacoustic transducer according to the present invention is configured with the same thickness as the conventional one as described above, the magnet can be made thicker than the conventional one. As a result, even when a high energy product magnet using neodymium or the like is used, the permeance coefficient is increased and it is more resistant to high temperature demagnetization than in the past. That is, the temperature reliability of the electrodynamic electroacoustic transducer according to the present invention is higher than before, and the electrodynamic electroacoustic transducer according to the present invention is an electrodynamic type that is more optimal as a transducer mounted on an automobile. Electroacoustic transducer.

  The electrodynamic electroacoustic transducer according to the present invention can be applied to all electronic devices having an electroacoustic transducer, and in particular, a cellular phone, a PDA, etc. in which the electroacoustic transducer needs to be reduced in size and thickness. This is useful for mobile devices. Further, the present invention can be applied to a display or the like that requires that the electroacoustic transducer has an elongated rectangular shape.

Cross-sectional view of the structure of the electrodynamic electroacoustic transducer 1 according to the first embodiment The perspective view which cut off some electrodynamic electroacoustic transducers 1 of FIG. FIG. 1 is a diagram in which an example of a magnetic circuit in the electrodynamic electroacoustic transducer 1 of FIG. The figure which shows the comparison of the magnetic flux density in a voice coil position about the magnetic circuit in the conventional example and the electrodynamic electroacoustic transducer 1 of FIG. The shape of the first magnetic pole 11 is a cylindrical shape with a coaxial through hole formed, and the lower surface of the second magnetic pole 12 is placed on the back side of the electrodynamic electroacoustic transducer 1 from the upper surface of the first magnetic pole 11. Arranged structure cross section 1 is a sectional view of the electrodynamic electroacoustic transducer 1 shown in FIG. 1 in which the plate 11b is omitted. The perspective view which cut off some electrodynamic electroacoustic transducers 1 of FIG. 1 is a sectional view of the electrodynamic electroacoustic transducer 1 shown in FIG. 1 in which the plate 12b is omitted. The perspective view which cut off some electrodynamic electroacoustic transducers 1 of FIG. 1 is a sectional view of the electrodynamic electroacoustic transducer 1 shown in FIG. 1 in which the plate 11b and the plate 12b are omitted. The perspective view which cut off a part of electrodynamic electroacoustic transducer 1 of FIG. Cross-sectional view of the structure of the electrodynamic electroacoustic transducer 2 according to the second embodiment The perspective view which cut off a part of electrodynamic type electroacoustic transducer 2 of FIG. Structural sectional view of the electrodynamic electroacoustic transducer 2 showing a configuration in which the first magnetic pole 21 has a frame shape. The perspective view which cut off a part of electrodynamic electroacoustic transducer 2 of FIG. Cross-sectional view of the structure of the electrodynamic electroacoustic transducer 3 according to the third embodiment The perspective view which cut off some electrodynamic electroacoustic transducers 3 of FIG. Cross-sectional view of the structure of the electrodynamic electroacoustic transducer 3 when the first magnetic pole 31 is composed of two rectangular parallelepipeds The perspective view which cut off some electrodynamic electroacoustic transducers 3 of FIG. The top view of the electrodynamic electroacoustic transducer 4 which concerns on 4th Embodiment Sectional drawing of structure of electrodynamic electroacoustic transducer 4 according to the fourth embodiment FIG. 21 is a diagram in which an example of a magnetic circuit in the electrodynamic electroacoustic transducer 4 of FIG. 21 is analyzed by a finite element method, and the flow of magnetic flux is expressed by a vector. In the electrodynamic electroacoustic transducer 4 of FIG. 21, a sectional view of the structure when plates 48 and 49 are added and the first magnet 41 has a through hole. The top view of the electrodynamic electroacoustic transducer 5 which concerns on 5th Embodiment Sectional drawing of structure of electrodynamic electroacoustic transducer 5 according to the fifth embodiment The top view of the electrodynamic electroacoustic transducer 6 which concerns on 6th Embodiment Sectional drawing of structure of electrodynamic electroacoustic transducer 6 according to a sixth embodiment The perspective view of the 1st magnet, the 2nd magnet, and the yoke in the electrodynamic electroacoustic transducer 6 The perspective view of the diaphragm in the electrodynamic electroacoustic transducer 6 Sectional drawing of structure of electrodynamic electroacoustic transducer 7 according to seventh embodiment FIG. 30 is a diagram in which an example of a magnetic circuit in the electrodynamic electroacoustic transducer 7 of FIG. 30 is analyzed by a finite element method and the flow of magnetic flux is represented by a vector. The figure which showed the magnetic flux density in each voice coil position of the electrodynamic electroacoustic transducer 1 and the electrodynamic electroacoustic transducer 7 with the curve, respectively. The figure which shows an example of the shape of the diaphragm in the adhering part of a diaphragm and a voice coil The figure which shows the other example of the shape of the diaphragm in the adhering part of a diaphragm and a voice coil The figure which shows the example by which the outer periphery of the diaphragm 15 was fixed to the support body 131 Front view and side view showing an example of the electrodynamic electroacoustic transducer 1 mounted on the mobile phone 80 The front view which shows an example of the electrodynamic electroacoustic transducer 3 mounted in the thin television 81, and the side view which showed the internal structure of a part of thin television 81 in illustration OA cross section The figure which shows an example of the electrodynamic electroacoustic transducer 1 mounted in the door 82 of a motor vehicle Cross-sectional view of structure of conventional electrodynamic electroacoustic transducer 200 Cross-sectional view of a conventional electromagnetic induction type electroacoustic transducer 300

Explanation of symbols

1, 2, 3, 4, 5, 6, 7 Electrodynamic electroacoustic transducers 11, 21, 31 First magnetic poles 11a, 12a, 21a, 22a, 31a, 31c, 32a, 32c Magnets 11b, 12b, 21b 22b, 31b, 31d, 32b, 32d Plates 12, 22, 32 Second magnetic poles 13, 23, 33, 43, 53, 63, 73 Yoke 14, 24, 34, 44, 54, 64 Voice coils 15, 25 , 35, 45, 55, 65 Diaphragm 41, 51, 61 First magnet 42, 52, 62 Second magnet 80 Mobile phone 81 Flat-screen TV 82 Door 83 Window 84 Main body

Claims (13)

A first magnetic pole portion formed of at least one solid including a magnet;
The bottom surface of the solid body is formed in at least one solid including a magnet, and a magnetic gap is formed between the first magnetic pole portion and a space excluding the top surface and the bottom surface space of the first magnetic pole portion. Is disposed above the upper surface of the first magnetic pole part, and
A yoke that magnetically couples and supports a lower surface of the first magnetic pole part and a side surface of the second magnetic pole part located on the opposite side of the magnetic gap;
A vibration plate that is disposed in a space in the upper surface direction of the first magnetic pole part and in a space in the lower surface direction of the second magnetic pole part, and whose outer periphery is supported by the yoke, and capable of vibrating in the vertical direction;
A voice coil fixed to the diaphragm and disposed in the magnetic gap;
The voice coil has an inner peripheral shape larger than an outer peripheral shape of the first magnetic pole portion,
The second magnetic pole part is disposed in a space excluding the first magnetic pole part and the space in the upper and lower surface directions of the voice coil,
The magnet included in the first magnetic pole portion is magnetized in the vibration direction of the diaphragm,
The magnet included in the second magnetic pole part is magnetized in a direction perpendicular to the vibration direction of the diaphragm so that the magnetic gap side is a pole opposite to the pole on the upper surface of the first magnetic pole part,
The diaphragm includes an edge portion that enables the diaphragm to vibrate, and at least a part of the edge portion faces a lower surface of the second magnetic pole portion, and the electrodynamic electroacoustic transducer . At least one of the first magnetic pole part and the second magnetic pole part is composed of a plate made of a magnetic material not including a magnet and the magnet on which two magnetic pole surfaces are formed,
The electrodynamic electroacoustic transducer according to claim 1, wherein the yoke is coupled to one magnetic pole surface of the magnet, and the plate is fixed to the other magnetic pole surface of the magnet.   2. The electrodynamic type according to claim 1, wherein the diaphragm is formed such that a portion facing the upper surface of the first magnetic pole portion has a convex shape relative to another portion. Electroacoustic transducer. The voice coil is fixed to either the upper surface side or the lower surface side of the diaphragm,
The diaphragm has a portion facing the upper surface of the first magnetic pole portion above the lower end of the voice coil, and a portion facing the lower surface of the second magnetic pole portion below the upper end of the voice coil. The electrodynamic electroacoustic transducer according to claim 1, wherein the electrodynamic electroacoustic transducer is formed in a shape.   The diaphragm is formed in any one shape selected from the group consisting of a circle, a rectangle, an ellipse, a polygon, and a shape in which only two opposite sides of the rectangle or polygon are formed in a semicircle. The electrodynamic electroacoustic transducer according to claim 1, wherein: The first magnetic pole part and the second magnetic pole part are annular bodies having a gap formed at the center thereof,
2. The electrodynamic electroacoustic transducer according to claim 1, wherein the first magnetic pole portion is disposed in a vertical space of an annular gap forming the second magnetic pole portion. The first magnetic pole portion is a columnar body,
The second magnetic pole part is an annular body having a gap formed in the center thereof,
2. The electrodynamic electroacoustic transducer according to claim 1, wherein the first magnetic pole portion is disposed in a vertical space of an annular gap forming the second magnetic pole portion. The voice coil has two straight portions opposed to a part of the wound portion,
The first magnetic pole portion includes at least one rectangular parallelepiped having a side parallel to each of the two linear portions and including a magnet,
The second magnetic pole portion includes two rectangular parallelepipeds each including a magnet,
In the voice coil, one of the linear portions is disposed in a magnetic gap formed between one of the second magnetic pole portions and the first magnetic pole portion, and the other linear portion is the second magnetic portion. 2. The electrodynamic electroacoustic transducer according to claim 1, wherein the electrodynamic electroacoustic transducer is disposed in a magnetic gap formed between the other magnetic pole part and the first magnetic pole part.   The electrodynamic electroacoustic transducer according to claim 8, wherein the second magnetic pole part includes at least two rectangular parallelepipeds each including a magnet.   The electrodynamic electroacoustic according to claim 8, wherein the first magnetic pole part is two rectangular parallelepipeds each having a side parallel to each of the two linear parts and each including a magnet. converter.   The electrodynamic electroacoustic transducer according to claim 8, wherein an opening is formed in a part of the yoke including at least a portion facing the second magnetic pole portion.   The diaphragm outside the winding portion of the voice coil is formed so as to protrude toward the opening at a portion facing the opening, and protrude toward the opposite side at the other portion. The electrodynamic electroacoustic transducer according to claim 11. An electronic device equipped with an electrodynamic electroacoustic transducer,
The electrodynamic electroacoustic transducer is
A first magnetic pole portion formed of at least one solid including a magnet;
The bottom surface of the solid body is formed in at least one solid including a magnet, and a magnetic gap is formed between the first magnetic pole portion and a space excluding the top surface and the bottom surface space of the first magnetic pole portion. Is disposed above the upper surface of the first magnetic pole part, and
A yoke that magnetically couples and supports a lower surface of the first magnetic pole part and a side surface of the second magnetic pole part located on the opposite side of the magnetic gap;
A vibration plate that is disposed in a space in the upper surface direction of the first magnetic pole part and in a space in the lower surface direction of the second magnetic pole part, and whose outer periphery is supported by the yoke, and capable of vibrating in the vertical direction;
A voice coil fixed to the diaphragm and disposed in the magnetic gap;
The voice coil has an inner peripheral shape larger than an outer peripheral shape of the first magnetic pole portion,
The second magnetic pole part is disposed in a space excluding the first magnetic pole part and the space in the upper and lower surface directions of the voice coil,
The magnet included in the first magnetic pole portion is magnetized in the vibration direction of the diaphragm,
The magnet included in the second magnetic pole portion is magnetized in a direction perpendicular to the vibration direction of the diaphragm so that the magnetic gap side is a pole opposite to the pole on the top surface of the first magnetic pole portion,
2. The electronic apparatus according to claim 1, wherein the diaphragm includes an edge portion that enables the diaphragm to vibrate, and at least a part of the edge portion faces a lower surface of the second magnetic pole portion.

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