243045.00007 8
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`Clean Copy Specification
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`CROSS REFERENCE TO RELATED APPLICAITONS
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`LINEAR VIBRATION MOTOR
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`This Application is
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`the National Stage of International Application No.
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`PCT/JP2017/0194l6 filed May 24, 2017, which in turn claims priority to Japanese
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`Application Serial No. 2016-133224 filed July 5, 2016. Both applications are
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`incorporated herein in their entirety.
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`FIELD OF TECHNOLOGY
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`The present invention relates to a linear vibration motor.
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`BACKGROUND
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`Vibration motors (or "vibration actuators") are built into mobile electronic devices,
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`and are broadly used as devices to communicate to the user, through a vibration, that
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`there is an incoming call, or that a signal, such as an alarm, has been generated, and have
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`become indispensable devices in wearable devices, which are carried on the body of the
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`user. Moreover,
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`in recent years vibration motors have been of interest as devices by
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`which to achieve haptics (skin-sensed feedback) in the human interfaces such as touch
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`panels.
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`Among the various forms of vibration motors that are under development, there is
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`interest in linear vibration motors that are able to generate relatively large vibrations
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`through linear reciprocating vibrations of a movable element. A conventional
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`linear
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`motor is provided with a weight and a magnet on a movable element side, where an
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`electric current is applied to a coil that is provided on the stator side to cause the Lorentz
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`forces that act on the magnet to form a driving force, to cause the movable element,
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`which is elastically supported along the direction of vibration, to undergo reciprocating
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`vibrations in the aXial direction (referencing Japanese Unexamined Patent Application
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`Publication 2016-13554).
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`SUMMARY OF THE INVENTION
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`Clean Copy Specification
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`Because the linear vibration motors are built into spaces within thin mobile electronic
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`devices or wearable electronic devices, there is the need for a shape that is thin in the
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`thickness direction, relative to the width direction that is perpendicular to the vibration
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`direction. At this time, if the movable element were to rotate or pivot around the aXis that
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`is the direction of vibration, both side portions of the movable element in the width
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`direction would strike the frame (case) that covers the movable element, resulting in a
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`drawback in that this would produce a noise during vibration. In linear vibration motors
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`that are to provide silent notification, to the operator, that a signal has occurred there is
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`the need to suppress the production of operating noise insofar as is possible.
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`The linear vibration motor according to the present invention is to handle such a
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`situation, and the object thereof is to provide a thin linear vibration motor that suppresses
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`the production operating noise.
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`Means for Solving the Problem
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`In order to solve such a problem, the linear vibration motor according to the present
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`invention is provided with the following structures:
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`A linear vibration motor includes a stationary element, a movable element that is
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`supported elastically, so as to enable vibration along an aXial direction, on the stationary
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`element, and a driving portion for causing the movable element to undergo reciprocating
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`vibration along the aXial direction, through the provision of a coil on the stationary
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`element, the provision of a driving magnet on the movable element, and the application
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`of an electric current to the coil while the driving magnet is attracted by magnetic
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`material that is provided on the stationary element side of the coil, wherein: the stationary
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`element is provided with a stationary magnet that is magnetized in a direction that is
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`perpendicular to the aXial direction, and the movable element is provided with a movable
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`magnet that opposes, while repelling, the stationary magnet.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`FIG.
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`1
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`is an exploded perspective diagram illustrating one example of a linear
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`vibration motor according to an embodiment according to the present invention.
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`FIG. 2 is an assembly oblique view (without the case) of the example depicted in
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`FIG. 1.
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`FIG. 3 is a front view of FIG. 2.
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`FIG. 4 is an explanatory diagram depicting the magnetization directions of the
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`magnets (the driving magnet, the stationary magnet, and the movable magnet) equipped
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`in the linear vibration motor according to the present invention.
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`FIG. 5 is an explanatory diagram illustrating a mobile electronic device in which is
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`provided a linear vibration motor according to an embodiment according to the present
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`invention.
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`Detailed Description
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`Embodiments according to the present invention will be explained below in reference
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`to the drawings. In the descriptions below, identical reference symbols in the different
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`drawings below indicate positions with identical functions, and redundant explanations in
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`the various drawings are omitted as appropriate. In each figure, the arrow in the X
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`direction indicates the direction of vibration of the movable element, the arrow in the Y
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`direction indicates the width direction of the movable element, and the arrow in the Z
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`direction indicates the thickness direction of the movable element.
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`FIG. 1 through FIG. 3 illustrate one example of a linear vibration motor according to
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`an embodiment according to the present
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`invention. The linear vibration motor
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`1
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`comprises a stationary element 10, a movable element 20, and a driving portion 30. The
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`stationary element 10, in the example in the figure, is equipped with a supporting plate 11
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`and a case 12. The movable element 20 is borne slidably in relation to the stationary
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`element 10, and is supported elastically so as to enable vibration along the axial direction
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`(the X direction in the figure). The movable element 20, in the example in the figure, is
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`equipped with a weight portion 21, a pair of coil springs 22 that extend and retract along
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`the X direction in the figure, where a spring supporting portion 2lT, for supporting one
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`end side of the coil spring 22, is provided on the weight portion 21, and a yoke 33 and
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`driving magnets 32 of the driving portion 30, described below, are attached.
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`The driving portion 30 comprises a coil 31 that is attached to the stationary element
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`10 (a supporting plate 11), and driving magnets 32 that are provided on the movable
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`element 20 (the weight portion 21). In this driving portion 30, a coil 31 is arranged in a
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`magnetic circuit that is formed from a pair of magnets 32, a yoke 33 on the movable
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`element 20 side for coupling with this pair of driving magnets 32, and a supporting plate
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`11, made from a magnetic material, that serves as a yoke on the stationary element 10
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`side, where the application of a driving signal to the coil 31 through a flexible circuit
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`board 34 causes the movable element 20 to vibrate, reciprocating along the axial direction
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`(the X direction in the figure) while the driving magnets 32 are attracted by the
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`supporting plate 11 of the magnetic material. The driving signal that is applied to the coil
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`31 is a pulse signal or an alternating current signal, or the like, of the resonant frequency
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`(the natural frequency) that is determined by the spring constant of the coil springs 22
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`and the mass of the movable element 20 (the weight portion 21). While,
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`in the
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`explanation above, the supporting plate 11 was of a magnetic material to serve as a yoke
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`on the stationary element 10 side, instead the supporting plate 11 may be a non-magnetic
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`body, and a separate yoke may be provided between the supporting plate 11 and the coil
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`3 1, so that the driving magnets 32 will be attracted by this yoke.
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`The linear vibration motor 1 can have a guide shaft 13. The guide shaft 13 is provided
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`extending in the axial direction (the X direction in the figure), and the movable element
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`20 is borne so as to enable sliding along the guide shaft 13. In the example in the figure,
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`the guide shaft 13 is secured on both ends to the stationary element 10 (the case 12), and
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`a bearing 23 is provided so as to bear the guide shaft 13 slidably on the movable element
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`20 side, however, the guide shaft 13 may be provided instead on the movable element 20
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`side, and the bearing may be provided so as to support the guide shaft 13 slidably on the
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`stationary element 10 side.
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`Moreover, in this linear motor 1, the stationary element 10 side is equipped with a
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`stationary magnet 14, and the movable element 20 side is equipped with a movable
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`magnet 24. Here the stationary magnet 14 is magnetized in a direction (the Z direction in
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`the figure) that is perpendicular to the axial direction (the X direction in the figure), and
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`is secured over the supporting plate 11, which is of a magnetic material. Moreover, the
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`stationary magnet 14 extends along the axial direction (the X direction in the figure. In
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`contrast, the movable magnet 24 is magnetized in the opposite direction of that of the
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`stationary magnet 14. Through this, the driving magnets 32 are attracted to the supporting
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`plate 11 side, which is a magnetic material, but the movable magnet 24 is in opposition,
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`repelling the stationary magnet 14. Because of this,
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`the movable magnet 24 that is
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`secured to the movable element 20 is subject to the repelling magnetic force from the
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`stationary magnet 14, so as to vibrate in a non-contacting state.
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`FIG. 4 depicts the magnetization directions of the driving magnets 32 of the driving
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`portion 30, the stationary magnet 14, and the movable magnet 24. The pair of driving
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`magnets 32 are magnetized, in mutually opposing directions, along the Z direction in the
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`figure, where the linear part, extending in the Y direction in the figure, of the coil 31 that
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`is disposed within the magnetic circuit that is structured from the pair of driving magnets
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`32, the yoke 33, and the supporting plate 11 of the magnetic material has magnetic flux
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`pass therethrough in the Z direction in the figure, and thus a driving force in the X
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`direction in the figure is applied to the driving magnets 32.
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`In contrast, the stationary magnet 14 and the movable magnet 24 are magnetized, in
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`mutually opposing directions, along the direction of the Z direction in the figure. The
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`movable magnet 24 that is provided on the movable element 20 is disposed so as to face
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`the stationary magnet 14 that extends along the X direction in the figure, and, similarly,
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`the driving magnets 32 that are disposed on the movable element 20 are disposed in
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`positions that do not interfere with the stationary magnet 14. Note that, in the example in
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`the figure, while the stationary magnet 14 is provided extending in the X direction in the
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`figure, and the movable magnet 24 opposes the stationary magnet 14, instead, conversely,
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`the movable magnet 24 may extend in the X direction in the figure, and the stationary
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`magnet 14 may oppose the movable magnet 24.
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`Given such a linear vibration motor 1, when the movable element 20 vibrates
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`reciprocating along the axial direction, the movable magnet 24 that is provided on the
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`movable element 20 vibrates while maintaining a constant spacing, in what is always a
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`non-contacting state, over the stationary magnet 14 that is provided on the stationary
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`element 10. Through this, the movable element 20 is not only able to vibrate while
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`suppressing the operating noise extremely, but is also able to vibrate in the axial direction
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`in a steady state wherein a rotation or pivoting around the axis is suppressed. This enables
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`suppression of the operating noise, eliminating the drawback of the noise that would be
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`produced through the movable element 20 contacting the supporting plate 11 or the case
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`12.
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`In the example depicted in FIG. 1 through FIG. 3, the movable element 20 is of a thin
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`shape wherein the dimension in the thickness direction thereof (the Z direction in the
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`figure) is less than the dimension in that the width direction (the Y direction in the
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`figure). Additionally, a bearing 23 is provided for bearing the guide shaft 13, on one end,
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`in the Y direction in the figure, of the movable element 20, and a movable magnet 24 is
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`provided on the other end side, in the Y direction in the figure, of the movable element
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`20. Through this, the movable element 20 is able to vibrate along the axial direction
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`while being supported fiat by the movable magnet 24 that is held by the guide shaft 13
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`and over the stationary magnet 14, making it possible to achieve a stabilized vibration
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`with parallel movement along the X-Y plane.
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`The stationary magnet 14 that is secured to the stationary element 10 side has a length
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`that is at least equal to the amplitude of the movable element 20 along the axial direction.
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`A recessed portion 21A, recessed in the Z direction in the figure (the thickness direction
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`of the movable element 20) is provided in the weight portion 21 of the movable element
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`20, and the movable magnet 24 is provided in this recessed portion 21A. Moreover, a
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`recessed portion 21B, which is recessed in the Z direction in the figure, and which is
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`provided extending in the X direction in the figure, is provided in the weight portion 21,
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`so that the stationary magnet 14 will be located within the recessed portion 21B when the
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`movable element 20 vibrates. The provision of the recessed portions 21A and 21B in this
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`way in the weight portion 21 enables the stationary magnet 14 and the movable magnet
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`24 to be provided while still suppressing the thickness (the height in the Z direction in the
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`figure) of the linear vibration motor 1.
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`FIG. 5 illustrates a mobile information terminal 100 as one example of a mobile
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`electronic device equipped with a linear vibration motor 1 according to an embodiment
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`according to the present invention. The mobile information terminal 100, provided with
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`the linear vibration motor 1 is able to convey silently, to a user, an incoming call in a
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`communication function, an alarm function, or the like. Moreover, this makes it possible
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`to produce a mobile information terminal 100 that facilitates superior mobility and design
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`quality through making the linear vibration motor 1 thinner and smaller. Furthermore,
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`because the linear vibration motor
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`1
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`is of a compact shape wherein the various
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`components are contained within a case 12 of a rectangular shape wherein the thickness
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`is suppressed, it can be mounted, with excellent space efficiency, within a thinner mobile
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`information terminal 100.
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`While embodiments according to the present
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`invention were described in detail
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`above, referencing the drawings, the specific structures thereof are not limited to these
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`embodiments, but rather design variations within a range that does not deviate from the
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`spirit and intent of the present invention are also included in the present invention.
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`Moreover, insofar as there are no particular contradictions or problems in purposes or
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`structures, or the like, the technologies of the various embodiments described above may
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`be used together in combination.
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