JP2005210550A - Actuator and acoustic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator capable of reducing sound leakage. <P>SOLUTION: The actuator is provided with a columnar magnetic distortion element 51 in which a partition plate 22 is disposed on one end side, and the one end is regulated by a fixed end and the other end side is regulated by a free end, the element extending along an axial direction; a driving coil 54 for generating a magnetic field for expanding/shrinking the element 51 by a driving current based on an acoustic signal; a vibration transmitting body 55 disposed on the other end side of the element 51, and transmitting vibration by the expansion/shrinkage of the element 51 to a plate 7; and a pair of magnets 52b, 53 repulsive each other along the axial direction. The pair of magnets 52b, 53 are disposed along the axial direction from the partition plate 22 to the vibration transmitting body 55. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an actuator and an acoustic device using a magnetostrictive element.

  As this type of acoustic device (actuator), an acoustic device disclosed in JP-A-9-261797 is known. This acoustic device includes a columnar magnetostrictive element and a drive coil wound around a bobbin with the columnar magnetostrictive element as the center. In this case, the columnar magnetostrictive element is disposed such that one end thereof is in contact with the disk-shaped magnetic body and the other end is in contact with the end of the magnetic member. In this case, a flange is formed on the magnetic member, and an elastic member is inserted between the flange and the case. Therefore, the magnetic member is biased toward the columnar magnetostrictive element by the inserted elastic member, so that the magnetic member is maintained in a state of being able to advance and retract in a direction along the vibration direction of the columnar magnetostrictive element. As a result, the disk-shaped magnetic body, the columnar magnetostrictive element, and the magnetic member are integrally connected in a state that allows vibration of the columnar magnetostrictive element.

In this acoustic device, when a drive current based on an acoustic signal is supplied, the drive coil generates a magnetic field oriented along the axial direction of the columnar magnetostrictive element. At this time, the columnar magnetostrictive element expands and contracts in the axial direction by applying the generated magnetic field. For this reason, a magnetic member vibrates in the axial direction according to expansion and contraction of the columnar magnetostrictive element. Therefore, by pressing this magnetic member against a vibrating body such as a diaphragm, the vibration is transmitted to the vibrating body, and sound is output from the vibrating body.
JP-A-9-261797 (page 3, FIG. 1)

  However, this acoustic device (actuator) has the following problems. That is, in this acoustic device, the magnetic member is biased toward the columnar magnetostrictive element by the elastic member so as to allow the columnar magnetostrictive element to vibrate, so that the disk-shaped magnetic body, the columnar magnetostrictive element, and the magnetic member are They are connected together. However, when the magnetic member is not pressed against the vibrating body, that is, when the output of sound is stopped, the elastic member is caused by the columnar magnetostrictive element due to, for example, the vibration frequency or the magnitude of vibration of the columnar magnetostrictive element. In some cases, the displacement due to expansion and contraction cannot be absorbed. In this case, the integrated connection of the disk-shaped magnetic body, the columnar magnetostrictive element, and the magnetic member is released. Therefore, there is a possibility that sound leakage based on the acoustic signal may occur due to the contact between the disk-shaped magnetic body and the magnetic member and the columnar magnetostrictive element in accordance with the expansion and contraction of the columnar magnetostrictive element. Is preferred.

  The present invention has been made in view of such a problem to be solved, and a main object of the present invention is to provide an actuator capable of reducing sound leakage. Another object of the present invention is to provide an audio device that can reduce sound leakage when sound output is stopped.

  In order to achieve the above object, the actuator according to the present invention has a columnar magnetostriction in which a stopper is disposed on one end side, the one end is defined as a fixed end, and the other end is defined as a free end and expands and contracts along the axial direction. An element, a magnetic field generating unit that generates a magnetic field for expanding and contracting the columnar magnetostrictive element by a driving current based on an acoustic signal, and a vibration generated by the expansion and contraction of the columnar magnetostrictive element. A vibration transmission body that transmits to the vibration body, and a pair of magnetic force generation means that repel each other in a direction away from each other along the axial direction, the pair of magnetic force generation means from the stopper to the vibration transmission body It is arrange | positioned along the said axial direction in between. In the present invention, “between the stopper and the vibration transmitting body” means a portion including the vibration transmitting body itself as a portion where the pair of magnetic force generating means are disposed. That is, the structure which forms a vibration transmission body in one side of a pair of magnetic force generation means is also included.

  In this case, it is preferable that at least one of the pair of magnetic force generating means is constituted by a permanent magnet.

  Further, it is preferable that the pair of magnetic force generating means is disposed adjacent to each other.

  An acoustic device according to the present invention includes the actuator according to any one of claims 1 to 3, and transmits vibration generated by expansion and contraction of the columnar magnetostrictive element to the vibrating body to output sound from the vibrating body. .

  In the actuator and the acoustic device according to the present invention, a stopper is disposed on one end side of the columnar magnetostrictive element, and a vibration transmitting body is disposed on the other end side of the columnar magnetostrictive element. Are provided with a pair of magnetic force generating means that repel each other in a direction away from each other. Therefore, when the vibration transmitting body is not pressed against the vibrating body, the space formed between the two due to the repulsive force of the pair of magnetic force generating means functions as an elastic body, so that the displacement due to the expansion and contraction of the columnar magnetostrictive element is absorbed. be able to. As a result, according to the actuator and the acoustic device, it is possible to reduce sound leakage caused by contact between a member in the actuator including the stopper and the vibration transmitting body and the columnar magnetostrictive element. On the other hand, when using the actuator and the acoustic device, the vibration transmitting body is pressed against the vibrating body so that the space functioning as the elastic body becomes narrower than the limit capable of maintaining elasticity. At this time, since the space functioning as an elastic body functions as an inelastic body, vibration due to expansion and contraction of the columnar magnetostrictive element is transmitted to the vibration transmitting body, and the vibration is transmitted to the vibrating body via the vibration transmitting body. Therefore, according to the actuator and the acoustic device, when transmitting vibration or outputting sound, the vibration is reliably transmitted to the vibrating body, and sound leakage is sufficiently reduced when transmitting vibration or stopping outputting sound. can do.

  In addition, according to the actuator and the acoustic device according to the present invention, since at least one of the pair of magnetic force generating means is configured by a permanent magnet, the structure is simpler than the configuration in which the magnetic force generating means is formed by an electromagnet. However, since the number of components to be configured can be reduced, component costs and assembly costs can be reduced. In addition, since the magnetic force generating means can be configured without using electric power as compared with the configuration in which the magnetic force generating means is formed by an electromagnet, the power consumption can be reduced.

  In addition, according to the actuator and the acoustic device according to the present invention, a pair of magnetic force generating means are disposed so as to be adjacent to each other, thereby forming a space that functions as an elastic body by using each magnetic force more effectively. Therefore, the displacement due to expansion and contraction of the columnar magnetostrictive element can be sufficiently absorbed. As a result, it is possible to further reduce sound leakage caused by contact between the members in the actuator including the stopper and the vibration transmitting body and the columnar magnetostrictive element.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an actuator and an acoustic device according to the invention will be described with reference to the accompanying drawings.

  First, a configuration of a pencil type speaker 1 to which an actuator and an acoustic device according to the present invention are applied will be described with reference to the drawings.

  As shown in FIG. 1, the pencil-type speaker 1 includes a cylindrical housing portion 2, an acoustic signal amplifying portion 3, a power source portion 4, and a vibration converting portion 5. It is configured to be able to output an acoustic signal when pressed against. As shown in the figure, the casing 2 includes an upper casing 2a and a lower casing 2b made of synthetic resin, and is formed at the end of each of the casings 2a and 2b. By being fitted and integrally connected by the fitted part, it is configured as an elongated pencil type as a whole. Further, the upper casing 2a is provided with a partition plate 21. The acoustic signal amplifying unit 3 is housed in an internal space on the rear end side partitioned by the partition plate 21, and the power source unit 4 is connected to the partition plate 21. 21 is housed in the internal space on the tip side divided by 21. On the other hand, a partition plate (stopper in the present invention) 22 that partitions the power supply unit 4 and the vibration conversion unit 5 is fixed to the lower housing 2b.

  As shown in FIG. 2, the acoustic signal amplifying unit 3 amplifies an acoustic signal input from the outside via the acoustic signal cable 6 and outputs a driving current generated to the driving coil 54 via a connection cable (not shown). . Further, as shown in FIG. 1, the acoustic signal amplifying unit 3 includes an amplifier board 31 disposed on the rear end side of the upper housing 2a. In the amplifier board 31, as shown in FIG. A power switch 32 and an acoustic signal input connector 33 are mounted. In this case, as shown in the figure, the power switch 32 includes a knob 34 that can be turned on / off by switching operation. The acoustic signal input connector 33 is configured as a plug that can be inserted into the jack 61 of the acoustic signal cable 6 for inputting an acoustic signal from the outside, as shown in FIG.

  As shown in FIGS. 1 and 2, the power supply unit 4 includes, for example, three dry batteries 41, 41, 41, a dry battery terminal 42 fixed to the partition plate 21, and a dry battery terminal 43 fixed to the partition plate 22. The power is supplied to the acoustic signal amplifying unit 3 via a connection cable connected to the dry battery terminals 42 and 43. In this case, the dry battery 41 is taken in and out from the opening on the tip end side of the upper housing 2a in a state separated from the lower housing 2b with the fitting portion removed.

  The vibration converting unit 5 is disposed in the inner space of the lower housing 2b, and includes a columnar magnetostrictive element 51, bias magnets 52a and 52b, a magnet 53, a drive coil 54, and a vibration transmitting body 55 as shown in FIGS. It is prepared for. The columnar magnetostrictive element 51 functions as an element that expands and contracts in the axial direction when a magnetic field is applied in a direction along the axial direction, and converts magnetic field fluctuations into mechanical vibration. The columnar magnetostrictive element 51 is, for example, formed of a super magnetostrictive material having a central composition of Tb0.34-Dy0.66-Fe1.90 that causes a large displacement of about 1500 ppm to 2000 ppm with respect to the axial direction in a magnetic field. Has been. Note that one end of the columnar magnetostrictive element 51 on the partition plate 22 side corresponds to a fixed end in the present invention, and the other end on the vibration transmission body 55 side corresponds to a free end in the present invention. The bias magnets 52a and 52b are, for example, permanent magnets formed in a disk shape, each having one end face defined as an S pole and each other end face defined as an N pole. For example, the bias magnet 52a is fixed (arranged) to the columnar magnetostrictive element 51 so that one end surface thereof contacts the end surface of the columnar magnetostrictive element 51 on the upper housing 2a side and the other end surface can contact the partition plate 22. ing. On the other hand, the bias magnet 52b corresponds to one of a pair of magnetic force generating means in the present invention, and is fixed to the end face of the columnar magnetostrictive element 51 on the vibration transmitting body 55 side with one end face facing the magnet 53. (Arrangement). In other words, the bias magnet 52b is arranged so that the magnetic pole on the other end surface facing the bias magnet 52a is an N pole that is different from the S pole of the bias magnet 52a. In this case, the bias magnets 52a and 52b apply a bias magnetic field so that the columnar magnetostrictive element 51 can be operated at an operating point that expands and contracts (vibrates) substantially linearly with respect to a change in the magnetic field in the axial direction.

  The magnet 53 corresponds to the other of the pair of magnetic force generating means in the present invention. As shown in FIG. 1, as an example, the magnet 53 is a permanent magnet formed in a disk shape, and one end surface on the bias magnet 52b side is S. The other end surface is defined as the N pole. Further, as shown in the figure, the other end surface of the magnet 53 is fixed to the flange 55a so that the one end surface of the magnet 53 is adjacent to the bias magnet 52b and opposite to one end surface of the bias magnet 52b. That is, the magnet 53 is repelled in a direction away from the bias magnet 52b by defining the magnetic pole of the one end surface facing the one end surface of the bias magnet 52b as the S pole as the same pole. It is arranged to fit. In this case, the number of components can be reduced by adopting a configuration in which the magnetism generating means in the present invention is formed using a magnet (in this example, the bias magnet 52b) that applies a bias magnetic field to the columnar magnetostrictive element 51. As a result, parts cost and assembly cost are reduced. The drive coil 54 corresponds to a magnetic field generation unit in the present invention, and is arranged such that its central axis is coaxial with the central axis of the columnar magnetostrictive element 51 as shown in FIGS. Further, as shown in FIG. 2, the drive coil 54 receives a drive current from the acoustic signal amplifying unit 3 via a connection cable, and generates a magnetic field on its axis (on the axis of the columnar magnetostrictive element 51).

  As shown in FIG. 1, the vibration transmission body 55 includes a disk-shaped flange 55 a, a shaft 55 b, and a tip contact portion 55 c, and is integrally configured. As shown in the figure, the flange 55a has a magnet 53 fixed to its upper end surface and abuts against the inner wall of the lower housing 2b at its lower end surface. In this case, the flange 55a is pressed against the lower housing 2b in a state where a space S is formed between the two due to the repulsive force between the magnet 53 and the bias magnet 52b. The shaft 55b has a tip contact portion 55c fixed to the tip surface thereof, and transmits the vibration of the flange 55a to the tip contact portion 55c. As shown in the figure, the tip contact portion 55c is formed in a hemispherical shape on the tip side, and when pressed against the plate body 7, the vibration of the vibration transmitting body 55 is applied to the plate body 7, for example. introduce. Therefore, as shown in the figure, the vibration transmitting body 55, the magnet 53, the bias magnet 52b, the columnar magnetostrictive element 51, the bias magnet 52a, and the partition plate 22 are both formed by the repulsive force of the two magnets 52b and 53. They are integrally connected via a space S therebetween. Further, when the tip contact portion 55c (vibration transmission body 55) is pressed against the plate body 7, the space S between the magnets 52b and 53 is narrowed, and the tip contact portion 55c (vibration transmission body 55) is relatively oriented toward the columnar magnetostrictive element 51 side. Move on. For this reason, in this state, the space S between the magnets 52b and 53 functions as an inelastic body.

  Next, the overall operation of the pencil type speaker 1 will be described.

  In the pencil type speaker 1, the acoustic signal amplifying unit 3 is externally connected via the acoustic signal cable 6 when the tip contact portion 55 c of the vibration transmitting body 55 is not pressed against the plate body 7, that is, when sound output is stopped. The input acoustic signal is amplified and a drive current is supplied to the drive coil 54. At this time, the drive coil 54 applies a magnetic field generated based on the supplied drive current to the columnar magnetostrictive element 51. For this reason, the columnar magnetostrictive element 51 expands and contracts in the axial direction according to the applied magnetic field. In this state, the space S between the two magnets 52b and 53 absorbs the displacement of the distance between the two magnets 52b and 53 due to the expansion and contraction of the columnar magnetostrictive element 51, and the repulsive force by both the magnets 52b and 53 transmits the vibration. The body 55, the magnet 53, the bias magnet 52b, the columnar magnetostrictive element 51, the bias magnet 52a, and the partition plate 22 are integrally connected. Therefore, sound leakage due to contact between the members is effectively and sufficiently reduced.

  On the other hand, when the tip contact portion 55c is pressed against the plate 7 with a predetermined pressure so that the space S between the magnets 52b and 53 is narrowed, the partition plate 22 has a stopper (that is, the weight of the human hand and the pencil-type speaker 1). In addition, the space S between the two magnets 52b and 53 is narrowed (that is, the distance between the two magnets 52b and 53 is shortened). At this time, the repulsive force of both the magnets 52b and 53 is large, and the one end surface of the bias magnet 52b is pressed against the plate 7 through the narrowed space S, the magnet 53, and the vibration transmitting body 55. And the other end surface of the bias magnet 52b is fixed to the predetermined position by the partition plate 22 via the columnar magnetostrictive element 51 and the bias magnet 52a, so that the narrowed space S is an inelastic body. It functions, and the displacement due to the expansion and contraction of the columnar magnetostrictive element 51 cannot be absorbed. Accordingly, at this time, vibration due to expansion and contraction of the columnar magnetostrictive element 51 is transmitted to the plate body 7 via the bias magnet 52b, the narrowed space S, the magnet 53, the flange 55a, the shaft 55b, and the tip contact portion 55c. The In this state, when the plate body 7 vibrates, an acoustic signal input from the outside is output from the plate body 7 as a sufficiently audible sound.

  Thus, according to this pencil type speaker 1, the partition plate 22 is disposed on one end side of the columnar magnetostrictive element 51, and the vibration transmitting body 55 is disposed on the other end side of the columnar magnetostrictive element 51. By arranging a pair of magnets 52b and 53 that repel each other in a direction away from each other between the plate 22 and the vibration transmitting body 55, the two magnets 52b are not pressed against the plate body 7. , 53 functions as an elastic body, so that displacement due to expansion and contraction of the columnar magnetostrictive element 51 can be absorbed. Therefore, according to the pencil type speaker 1, when the sound is output, the plate body 7 is vibrated to surely output the sound, and when the sound output is stopped, the partition plate 22 and the bias magnet 52 a in the pencil type speaker 1 are output. , 52b, and the columnar magnetostrictive element 51 can sufficiently reduce sound leakage. Furthermore, according to this pencil type speaker 1, since the space S between the magnets 52b and 53 functions as an elastic body, the force applied to the end face of the columnar magnetostrictive element 51 due to adhesion or dropping of foreign matter is absorbed. As a result, the columnar magnetostrictive element 51 can be prevented from being damaged. Further, even when breakage occurs, the degree of breakage can be reduced.

  Moreover, according to this pencil type speaker 1, since both the magnets 52b and 53 are comprised with the permanent magnet, compared with the structure which forms both the magnets 52b and 53 with an electromagnet, it is a component comprised while being simple structure. Since the number can be reduced, parts cost and assembly cost can be reduced. In addition, compared to a configuration in which both magnets 52b and 53 are formed of electromagnets, magnetic force can be generated without using power, so that power consumption can be reduced.

  Moreover, according to this pencil type speaker 1, by arranging the magnets 52b and 53 so as to be adjacent to each other, the space S functioning as an elastic body can be formed by using each magnetic force more effectively. Therefore, the displacement due to expansion and contraction of the columnar magnetostrictive element 51 can be sufficiently absorbed. Therefore, sound leakage caused by the contact between the columnar magnetostrictive element 51 and the members such as the partition plate 22 and the bias magnets 52a and 52b in the pencil speaker 1 including the partition plate 22 and the vibration transmitting body 55 can be further reduced. it can.

  The present invention is not limited to the configuration described above. For example, the configuration in which the bias magnet 52b and the magnet 53 formed of permanent magnets are disposed has been described above. However, as in the pencil type speaker 1A shown in FIG. 3, one or both of the bias magnet 52b and the magnet 53 are electromagnets. Can also be configured. In the following description, components having the same functions as those of the pencil type speaker 1 are denoted by the same reference numerals, and redundant description is omitted.

  The pencil type speaker 1A is configured in the same manner as the pencil type speaker 1 except for the vibration conversion unit 5A. On the other hand, as shown in FIG. 3, the vibration converting unit 5A includes a columnar magnetostrictive element 51, a drive coil 54, a vibration transmitting body 55, a ferromagnetic body 56, a coil 57, a ferromagnetic body 58, and a coil 59. Yes. As an example, the ferromagnetic body 56 is formed in a disk shape, and is fixed (arranged) to the end face of the columnar magnetostrictive element 51 on the vibration transmitting body 55 side. The coil 57 is supplied with a direct current from the amplifier substrate 31 via a cable (not shown), and operates the columnar magnetostrictive element 51 at an operating point that expands and contracts (vibrates) substantially linearly with respect to the fluctuation of the magnetic field in the axial direction. Thus, a DC bias magnetic field can be applied, and a DC magnetic field can be applied to the ferromagnetic material 56. In this case, the ferromagnetic material 56 and the coil 57 together constitute an electromagnet as one of a pair of magnetic force generating means in the present invention. As shown in the drawing, the other end surface of the ferromagnetic body 58 is fixed to the flange 55a so that one end surface thereof faces the ferromagnetic body 56. The coil 59 is configured to be able to apply a DC magnetic field to the ferromagnetic body 58 by being supplied with a DC current from the amplifier substrate 31 via a cable (not shown). In this case, the ferromagnetic material 58 and the coil 59 constitute an electromagnet corresponding to the other of the pair of magnetic force generating means in the present invention. The coil 59 is wound so that the direction of the magnetic field applied on the axis of the ferromagnetic material 58 is opposite (in the opposite direction) to the direction of the magnetic field applied on the axis of the ferromagnetic material 56 by the coil 57. Has been. Therefore, the electromagnet formed by the ferromagnetic body 58 and the coil 59 is configured to repel the electromagnet formed by the ferromagnetic body 56 and the coil 57 in a direction away from each other.

  In the pencil type speaker 1A, an electromagnet formed by the ferromagnetic body 56 and the coil 57 and an electromagnet formed by the ferromagnetic body 58 and the coil 59 are respectively connected to the bias magnet 52b and the magnet 53 in the pencil type speaker 1. Correspondingly works similarly. Therefore, according to this pencil type speaker 1A, although the electric power which operates the coil 57 and the coil 59 is required, the effect similar to the pencil type speaker 1 can be show | played.

  Note that the configuration in which both the electromagnet formed by the ferromagnetic material 56 and the coil 57 and the electromagnet formed by the ferromagnetic material 58 and the coil 59 are used in place of the permanent magnet has been described above, but only one of them is an electromagnet. It can also be configured. Even with this configuration, sound leakage can be sufficiently reduced in the same manner as the configuration of the pencil type speakers 1 and 1A.

  Further, a configuration in which a pair of magnets (bias magnet 52b and magnet 53, or ferromagnetic body 56 and coil 57, ferromagnetic body 58 and coil 59) is disposed between the columnar magnetostrictive element 51 and the vibration transmitting body 55. As described above, instead of this pair of magnets or in addition to this pair of magnets, it is also possible to employ a configuration in which another pair of magnets is disposed between the partition plate 22 and the tip contact portion 55c. it can. Even with this configuration, sound leakage can be sufficiently reduced in the same manner as the configuration of the pencil type speakers 1 and 1A. Furthermore, instead of the magnet 53 (the other of the pair of magnets), the vibration transmitting body 55 itself can be formed of a magnet. According to this configuration, the number of parts can be reduced.

  In addition, the configuration in which the pair of magnets (the bias magnet 52b and the magnet 53, or the ferromagnetic body 56 and the coil 57, the ferromagnetic body 58, and the coil 59) are disposed adjacent to each other is described above, but is not limited thereto. It is also possible to employ a configuration in which another member such as a vibration transmitting member is disposed between the pair of magnets, and the two magnets are disposed apart from each other. Even with this configuration, although the distance between the pair of magnets is longer and the repulsive force of the magnetic force is slightly weaker than the configuration of the pencil type speakers 1 and 1A, sound leakage can be sufficiently reduced. .

  Further, the bias magnet 52b has a function of applying a bias magnetic field so that the columnar magnetostrictive element 51 can be operated at an operating point that expands and contracts (oscillates) substantially linearly with respect to the fluctuation of the magnetic field in the axial direction, and the magnetic force of the magnet 53. Although the above has been described with respect to the configuration that has the function of forming the space S as the elastic body by the repulsive force, it is not limited to this configuration, and only the function of forming the space S as the elastic body can be provided. In this case, a configuration in which another separate magnet applies a bias magnetic field to the columnar magnetostrictive element 51 may be employed. Further, the ferromagnetic body 56 and the coil 57 in the pencil type speaker 1A can have only the function of forming the space S as an elastic body. Even with this configuration, sound leakage can be sufficiently reduced in the same manner as the configuration of the pencil type speakers 1 and 1A.

  Further, the pencil type speakers 1 and 1A having one columnar magnetostrictive element 51 are described above. However, the number of the columnar magnetostrictive elements 51 is not limited to one, and a plurality of columnar magnetostrictive elements 51 may be provided. In this configuration, a pair of magnets can be disposed between the columnar magnetostrictive elements 51 and 51.

  Further, in the configuration of the pencil type speaker 1 described above, the configuration in which the bias magnet 52b and the magnet 53 are opposed to each other with the S poles is described, but the configuration is not limited to this configuration and the configuration in which the N poles are opposed to each other is adopted. Of course you can. Furthermore, although the pencil type speakers 1 and 1A in which the actuator according to the present invention is applied to an acoustic device have been described above, the actuator can be applied not only to an acoustic device but also to various devices that transmit vibration.

1 is a cross-sectional view showing a configuration of a pencil type speaker 1. FIG. 1 is a block diagram showing an electric circuit of a pencil type speaker 1. FIG. It is sectional drawing which shows the structure of the pencil-type speaker 1A.

Explanation of symbols

1,1A Pencil type speaker 22 Partition plate 51 Columnar magnetostrictive element 52b Bias magnet 53 Magnet 54 Drive coil 55 Vibration transmitting body 56, 58 Ferromagnetic material 57, 59 Coil

Claims (4)

A stopper is provided on one end side, the one end is defined as a fixed end, the other end side is defined as a free end, and the columnar magnetostrictive element expands and contracts along the axial direction, and the columnar magnetostriction is driven by a driving current based on an acoustic signal. A magnetic field generator for generating a magnetic field for expanding and contracting the element; a vibration transmitting body disposed on the other end side of the columnar magnetostrictive element; and transmitting vibrations due to expansion and contraction of the columnar magnetostrictive element to the vibrating body; and the axial direction And a pair of magnetic force generating means that repel each other in a direction away from each other,
The pair of magnetic force generation means is an actuator disposed along the axial direction between the stopper and the vibration transmitting body.   The actuator according to claim 1, wherein at least one of the pair of magnetic force generation means is formed of a permanent magnet.   The actuator according to claim 1, wherein the pair of magnetic force generation means are disposed adjacent to each other.   An acoustic device that includes the actuator according to any one of claims 1 to 3, and transmits vibrations generated by expansion and contraction of the columnar magnetostrictive element to the vibrating body to output sound from the vibrating body.

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