JP2005210609A - Actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator capable of reducing leaked magnetic flux. <P>SOLUTION: The actuator is provided with a non-magnetic casing unit 2; a columnar magnetic distortion element 51 extending along an axial direction 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 is regulated by a free end, the element extending; a driving coil 53 for generating a magnetic field for expanding/shrinking the element 51 by a driving current based on an acoustic signal; a vibration transmitting body 54 disposed on the other end side of the element 51 so that a tip abutting portion 57 to be coupled to an integrally formed flange 55 and shaft 56 may abut against a plate 8, and vibration by expansion/shrinkage of the element 51 may be transmitted to the plate 8; and a yoke disposed between the element 51 in an axial line direction and the portion 57 in the transmitting body 54. The element 51, the driving coil 53 and the yoke are disposed in the casing unit 2, and at least the portion 57 of the transmitting body 54 is formed of a non-magnetic material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  As this type of actuator, an actuator (bone-conducting sound transmission device) disclosed in Japanese Patent Laid-Open No. 9-261797 is known. This actuator includes a columnar magnetostrictive element, a drive coil wound around a bobbin around the columnar magnetostrictive element, and a disk-shaped magnetic body and a magnetic member that constitute a magnetic circuit when driving the columnar magnetostrictive element. ing. 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. The magnetic member has a flange, 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 actuator, 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, and the disk-shaped magnetic body and the magnetic member generate a magnetic flux in the columnar magnetostrictive element. Functions as a magnetic circuit that collects 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 the 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 actuator has the following problems. That is, in this actuator, when the drive coil is energized, a magnetic circuit is constituted by the magnetic member. In this case, the tip portion of the magnetic member is exposed from the case so that it can be pressed against the vibrating body. For this reason, as a result of the structure in which the tip portion of the magnetic member is easily in contact with the article, the magnetic flux easily leaks to the outside of the actuator through the magnetic member when the drive coil is energized. Therefore, when there is a magnetically weak article such as a magnetic card or magnetic tape near the tip of the magnetic member, magnetic information may be destroyed by the leaked magnetic flux. 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 leakage magnetic flux.

  In order to achieve the above object, an actuator according to the present invention includes a non-magnetic case, a stopper disposed on one end side, the one end defined as a fixed end, and the other end defined as a free end. A columnar magnetostrictive element that expands and contracts along a magnetic field, a magnetic field generation unit that generates a magnetic field that expands and contracts the columnar magnetostrictive element by a drive current based on an acoustic signal, and a tip contact part that is connected to the main body part abuts against the vibration object. A vibration transmitting body disposed on the other end side of the columnar magnetostrictive element so that vibration due to expansion and contraction of the columnar magnetostrictive element can be transmitted to the vibration target body, and the columnar magnetostrictive element and the vibration transmitting body in the axial direction. A yoke portion disposed between the tip abutting portions, and the columnar magnetostrictive element, the magnetic field generating portion, and the yoke portion are disposed in the case and at least in front of the vibration transmitting body. Actuator tip end abutting portion is formed of a non-magnetic material.

  In this case, it is preferable that the main body portion and the yoke portion of the vibration transmitting body are integrated.

  Further, it is preferable that the yoke portion is formed of a ferromagnetic material embedded in the main body portion of the vibration transmitting body.

  Preferably, the yoke portion is formed of a ferromagnetic material plated on the main body portion of the vibration transmitting body.

  According to the actuator of the present invention, since the columnar magnetostrictive element, the magnetic field generating unit, and the yoke unit are arranged in the nonmagnetic case, each part constituting the magnetic circuit is covered with the nonmagnetic material. The leakage magnetic flux from can be sufficiently reduced. Further, since at least the tip contact portion of the vibration transmitting body is made of a non-magnetic material, the tip contact portion moves away from the magnetic circuit, so that the leakage magnetic flux from the tip contact portion can be sufficiently reduced. Therefore, even if the tip contact portion of the actuator is brought close to an article that is weak against magnetism, destruction of magnetic information can be effectively prevented.

  Further, according to the actuator according to the present invention, since the body portion and the yoke portion of the vibration transmitting body are integrated, the number of parts can be reduced, so that the assembly time can be sufficiently reduced. As a result, the manufacturing cost of the actuator can be sufficiently reduced.

  Also, by forming a yoke part by embedding a ferromagnetic body in the main body part of the vibration transmission body, a vibration transmission body in which the yoke part is configured separately or a vibration transmission body integrated without embedding the yoke part in the main body part Compared to the above, the length of the vibration transmitting body can be sufficiently shortened, so that the actuator can be sufficiently downsized. In this case, in order to further move the tip contact portion of the vibration transmitting body away from the yoke portion, it is preferable to form the yoke portion on the end surface of the main body portion on the columnar magnetostrictive element side.

  In addition, since the yoke part is formed of a ferromagnetic material plated on the main body part of the vibration transmitting body, the yoke part can be formed thin, so that the size and size can be reduced compared to the structure in which the yoke part is embedded in the main body part. Weight reduction can be realized. In this case, in order to further move the tip contact portion of the vibration transmitting body away from the yoke portion, it is preferable to form the yoke portion on the end surface of the main body portion on the columnar magnetostrictive element side.

  Hereinafter, the best mode of an actuator according to the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the pencil type speaker 1 to which the actuator according to the present invention is applied will be described with reference to the drawings.

  As shown in FIG. 1, the pencil-type speaker 1 includes a cylindrical casing (case in the present invention) 2, an acoustic signal amplifying unit 3, a power supply unit 4, and a vibration converting unit 5, the tip of which is a vibrating body. For example, an acoustic signal can be output when pressed against the plate 8. As shown in the figure, the housing portion 2 includes an upper housing 2a and a lower housing 2b each formed of a synthetic resin as a nonmagnetic material in the present invention. By being fitted and integrally connected by a fitting portion formed at each end portion of 2b, 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 7 and generates a driving current generated in a driving coil 53 (described later) via a connection cable (not shown). Output. 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 into which the jack 71 of the acoustic signal cable 7 for inputting an acoustic signal from the outside can be inserted, 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 as shown in FIGS. 1 and 2, a columnar magnetostrictive element 51, bias magnets 52a and 52b, a drive coil 53, a vibration transmitting body 54, and 4 for example. Two springs 58, 58,... 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 54 side corresponds to a free end in the present invention. The bias magnet 52 a is fixed (arranged) so that one end surface thereof is in contact with the end surface of the columnar magnetostrictive element 51 on the upper housing 2 a side and the other end surface is in contact with the partition plate 22. Further, one end surface of the bias magnet 52b comes into contact with the end surface of the columnar magnetostrictive element 51 on the vibration transmitting body 54 side, and the other end surface can come into contact with the flange 55 (see FIG. 1) of the vibration transmitting body 54. It is fixed (arranged) in a state. 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 drive coil 53 corresponds to a magnetic field generation unit in the present invention, and is disposed 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 53 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 54 includes a disk-shaped flange 55, a columnar shaft 56, and a tip contact portion 57. The flange 55 and the shaft 56 together constitute the main body of the vibration transmitting body in the present invention. As shown in the figure, as an example, the flange 55 and the shaft 56 are integrated with a nonmagnetic brass. Is formed. In this case, as an example, as shown in FIG. 3, the flange 55 has a recess 60 having a diameter approximately the same as the diameter of the columnar magnetostrictive element 51 and a depth of about 2 mm at the central portion on the upper end surface on the bias magnet 52b side. In addition, a yoke portion 59 of a ferromagnetic material (iron as an example) formed in the same shape (complementary shape) as the recess 60 is embedded in the recess 60. Since the yoke portion 59 has a high magnetic permeability, it forms a magnetic circuit together with the columnar magnetostrictive element 51, the bias magnets 52a and 52b, and the drive coil 53, and collects the magnetic flux generated by the drive coil 53 to the columnar magnetostrictive element 51. On the other hand, it is applied more uniformly and more. The flange 55, the shaft 56, and the tip contact portion 57 are formed of a nonmagnetic material. Therefore, the distance between the tip contact portion 57 and the magnetic circuit is longer than the configuration in which the tip contact portion 57 or the like is formed of a ferromagnetic material as a yoke portion. The leakage magnetic flux to the outside is reduced.

  1, the flange 55 is in contact with the bias magnet 52b at the upper end surface in which the yoke portion 59 is embedded, and is in contact with the springs 58, 58,. As shown in the figure, each spring 58 has one end abutted against the flange 55 and the other end abutted against the inner wall of the lower housing 2b, and urges the flange 55 toward the columnar magnetostrictive element 51. In a contracted state, it is disposed in the internal space of the lower housing 2b. The shaft 56 has a tip contact portion 57 fixed to the tip surface thereof, and transmits the vibration of the flange 55 to the tip contact portion 57. As shown in the figure, the tip contact portion 57 is formed in a hemispherical shape with a non-magnetic synthetic resin and is pressed against the plate 8 as an example. Is transmitted to the plate 8. Therefore, as shown in the figure, when the flange 55 is urged by the spring 58, the flange 55, the bias magnet 52b, the columnar magnetostrictive element 51, and the bias magnet 52a are integrally connected, and the vibration transmitting body. 54 is maintained in a state in which it can advance and retreat (vibrates) along the axial direction. For this reason, the vibration transmitting body 54 moves in a direction away from the partition plate 22 when the columnar magnetostrictive element 51 extends, and moves in a direction closer to the partition plate 22 when the columnar magnetostrictive element 51 contracts. . As a result, the vibration transmitting body 54 (flange 55) vibrates in a direction along the expansion / contraction direction according to the expansion / contraction of the columnar magnetostrictive element 51.

  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 amplifies an acoustic signal input from the outside via the acoustic signal cable 7 and supplies a driving current to the driving coil 53. In this case, the drive coil 53 applies a magnetic field generated based on the supplied drive current to the columnar magnetostrictive element 51. At this time, since the magnetic permeability of the yoke portion 59 is high, the magnetic flux generated by the drive coil 53 is collected in the yoke portion 59, so that more magnetic flux is applied to the columnar magnetostrictive element 51 in a more uniform state. For this reason, the columnar magnetostrictive element 51 expands and contracts in the axial direction in accordance with the applied magnetic field (magnetic flux). At this time, a leakage magnetic flux is generated from the yoke portion 59 mainly toward the tip contact portion 57 side. On the other hand, in the pencil type speaker 1, the distance from the yoke portion 59 to the tip contact portion 57 is long, and the flange 55, the shaft 56, and the tip contact portion 57 are formed of a nonmagnetic material. Therefore, the magnetic flux leakage from the tip contact portion 57 to the outside of the pencil type speaker 1 is sufficiently reduced. As a result, even if a magnetically weak article such as a magnetic card or a magnetic tape is brought close to the tip contact portion 57, destruction of magnetic information or the like is effectively prevented.

  On the other hand, when the tip contact portion 57 is pressed against the plate body 8, the partition plate 22 functions as a stopper (that is, inertia mass together with the weight of the human hand and the pencil type speaker 1). For this reason, vibration due to expansion and contraction of the columnar magnetostrictive element 51 is transmitted to the plate body 8 via the bias magnet 52 b, the flange 55, the shaft 56 and the tip contact portion 57. In this case, when the plate body 8 vibrates, an acoustic signal input from the outside is output from the plate body 8 as a sufficiently audible sound.

  As described above, according to the pencil type speaker 1, the columnar magnetostrictive element 51, the drive coil 53, and the yoke portion 59 are arranged in the nonmagnetic body portion 2, so that each part constituting the magnetic circuit is provided. Since it is covered with a non-magnetic material, the leakage magnetic flux from the housing part 2 can be sufficiently reduced. In addition, since the tip contact portion 57 of the vibration transmitting body 54 is formed of a non-magnetic material, the tip contact portion 57 moves away from the magnetic circuit, so that the leakage magnetic flux from the tip contact portion 57 can be sufficiently reduced. it can. Therefore, even if the tip contact portion 57 of the pencil type speaker 1 is brought close to an article that is weak against magnetism, destruction of magnetic information can be effectively prevented.

  Moreover, according to this pencil type speaker 1, since the flange 55 and the yoke part 59 of the vibration transmission body 54 are integrated, the number of parts of the pencil type speaker 1 can be reduced, so that the assembly time can be reduced. As a result of being able to reduce sufficiently, the manufacturing cost of the pencil type speaker 1 can be reduced sufficiently. In addition, since the yoke portion 59 is formed by embedding a ferromagnetic material in the flange 55 of the vibration transmission body 54, the vibration transmission body having a yoke portion formed separately and the yoke portion are integrated without being embedded in the main body portion. Since the length of the vibration transmission body 54 can be sufficiently shortened compared with the vibration transmission body, the pencil type speaker 1 can be sufficiently downsized.

  The present invention is not limited to the configuration described above. For example, the configuration in which the yoke portion 59 is embedded in the flange 55 has been described above, but instead of the flange 55 and the yoke portion 59 as in the vibration transmitting body 54A (flange 55A) in the pencil type speaker 1A shown in FIGS. A configuration in which the yoke portion 61 is formed by plating a ferromagnetic material (for example, nickel) on the end surface on the bias magnet 52b side of the flange 55A formed of a non-magnetic brass may be employed. In this case, the pencil type speaker 1A is configured in the same manner as the pencil type speaker 1 except that the yoke portion 61 is formed by nickel plating on the upper end surface of the flange 55A. Accordingly, since the basic configuration and operation itself are the same as those of the pencil type speaker 1, the same components are denoted by the same reference numerals, and redundant description is omitted. As an example, the flange 55A and the shaft 56 are a disc-shaped flange 55A and a columnar shaft 56 that are integrally formed of non-magnetic brass.

  According to this pencil-type speaker 1A, since the yoke portion 61 is formed by plating the flange 55A, the yoke portion 61 can be formed thin, so that the size and size can be reduced compared with the configuration in which the yoke portion 59 is embedded. Weight reduction can be realized.

  In addition, as the pencil type speakers 1 and 1A, the yoke portions 59 and 61 are integrally formed on the end surfaces of the flanges 55 and 55A on the columnar magnetostrictive element 51 side. A configuration in which the shaft 56 is formed integrally with the end surface on the contact portion 57 side may be employed. In addition, the configuration in which the yoke portion 59 (or 61) is disposed only on the vibration transmitting body 54 side of the columnar magnetostrictive element 51 has been described above. However, a configuration in which yoke portions are disposed at both ends of the columnar magnetostrictive element 51 may be employed. it can. In addition, a configuration in which the yoke portion 59 is disposed inside one or both of the flange 55 and the shaft 56 may be employed. Even with these configurations, the leakage magnetic flux from the tip contact portion 57 can be sufficiently reduced. Furthermore, although the configuration in which both the bias magnets 52a and 52b are disposed has been described above, a configuration in which only one of the bias magnets 52a and 52b is disposed may be employed.

  Further, as the pencil type speaker 1, the yoke portion 59 is formed integrally with the flange 55 and the bias magnet 52 b is formed separately from the flange 55. However, both the yoke portion 59 and the bias magnet 52 b are flanged. It is also possible to adopt a configuration of being embedded in 55 and integrated. According to this configuration, the pencil type speaker 1 can be further miniaturized.

  Furthermore, although the pencil type speaker 1 having a configuration in which one columnar magnetostrictive element 51 is disposed is described above, the number of columnar magnetostrictive elements 51 is not limited to one, and a plurality of columnar magnetostrictive elements 51 may be disposed. In this configuration, a bias magnet may be appropriately disposed between the columnar magnetostrictive elements 51 and 51.

  Moreover, 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 according to the present invention can be applied not only to an acoustic device but also to various devices that transmit vibration.

It is sectional drawing which shows the structure of the pencil-type speaker 1 (1A). It is a block diagram which shows the electric circuit of the pencil-type speaker 1 (1A). 6 is a top view of the flange 55 as viewed from the columnar magnetostrictive element 51 side. FIG. It is the top view seen from the columnar magnetostrictive element 51 side of flange 55A.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Pencil type | mold speaker 5 Vibration conversion part 51 Columnar magnetostrictive element 53 Drive coil 54,54A Vibration transmission body 55,55A Flange 56 Axis 57 Tip contact part 59,61 Yoke part

Claims (4)

  A non-magnetic case, a columnar magnetostrictive element which is provided with a stopper 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, and an acoustic signal A magnetic field generator for generating a magnetic field for expanding and contracting the columnar magnetostrictive element by a driving current based thereon, and a tip contact portion connected to the main body abut against the object to be vibrated, and subject the vibration due to the expansion and contraction of the columnar magnetostrictive element to the vibration target. A vibration transmitting body disposed on the other end side of the columnar magnetostrictive element so as to be able to transmit to the body, and the columnar magnetostrictive element in the axial direction and the tip contact portion of the vibration transmitting body. An actuator, wherein the columnar magnetostrictive element, the magnetic field generating unit, and the yoke unit are disposed in the case, and at least the tip contact portion of the vibration transmitting body is formed of a non-magnetic material. .   The actuator according to claim 1, wherein the yoke portion is configured integrally with the main body portion of the vibration transmitting body.   The actuator according to claim 2, wherein the yoke portion is formed of a ferromagnetic material embedded in the main body portion of the vibration transmitting body.   The actuator according to claim 2, wherein the yoke portion is formed of a ferromagnetic material plated on the main body portion of the vibration transmitting body.

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