JP2019063693A - Linear vibration motor - Google Patents

Abstract

To enable the thinning of a linear vibration motor, and to suppress the generation of noise by suppressing rotational vibration about a shaft of a movable element even when the movable element is vibrated along the shaft.SOLUTION: A linear vibration motor is equipped with a frame body; a movable element elastically supported by the frame body so as to vibrate in one axial direction; and a magnet fixed to one of the frame body and the movable element and a coil fixed to the other. The linear vibration motor is also equipped with a driving source which reciprocates and vibrates the movable element in the one axial direction by the energization of a drive signal to the coil; a shaft which guides vibrations of the movable element along the one axial direction; and a bearing which slidably journals the shaft. The shaft and the baring have non-circular shaped cross sections vertical to the one axial direction at least in a slide contact part of them.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a linear vibration motor.

  A vibration motor (or vibration actuator) is built in a portable electronic device and widely used as a device for transmitting a signal generation such as an incoming call or an alarm to a portable person by vibration, and in a wearable electronic device which a portable person wears and carries. , Has become an indispensable device. In addition, a vibration motor has recently attracted attention as a device for realizing haptics (skin sensory feedback) in a human interface such as a touch panel.

  Among various types of vibration motors, linear vibration motors that can generate relatively large vibrations due to linear reciprocating vibration of a mover are attracting attention. In the conventional linear vibration motor, a weight and a magnet are provided on the mover side, and Lorentz force acting on the magnet becomes a driving force by energizing the coil provided on the stator side, and the movable is elastically supported along the vibration direction The element is oscillated back and forth in one axial direction. Among such conventional linear vibration motors, there is known one in which a shaft is disposed along the vibration direction, coil springs are disposed on both sides in the vibration direction of the mover, and the mover is vibrated while being guided by the shaft ( See Patent Document 1 below).

JP, 2016-13554, A

  The conventional linear vibration motor described above vibrates the mover while being guided by the shaft to obtain stable straightness of reciprocating vibration, and the shaft holds the mover at the time of drop impact, so it is hard to be damaged. There is an advantage. However, since the mover is formed in a cylindrical shape and the shaft is penetrated along its central axis, there is a structural limit to reducing the thickness of the linear vibration motor.

  On the other hand, with the miniaturization and thinning of portable electronic devices, demands for further miniaturization and thinning have been made to vibration motors equipped therein. In particular, in an electronic device provided with a flat panel display unit such as a smartphone, since the space in the device in the thickness direction orthogonal to the display surface is limited, high demand for thinning of the vibration motor disposed there is required There is.

  As a structure of a linear vibration motor capable of coping with such a demand for thinning, it has been studied to make the shape of the mover thin (for example, a flat rectangular cross-sectional shape). However, in the case of vibrating such a thin movable element along the shaft, when the movable element is rotationally oscillated around the shaft, the side far from the shaft of the movable element is repeatedly used as a frame surrounding the movable element. There is a problem that the collision makes it easy to generate abnormal noise.

  It is an object of the present invention to cope with such a situation. That is, the present invention makes it possible to reduce the thickness of the linear vibration motor, suppress the rotational vibration of the mover around the shaft even when vibrating the mover along the shaft, and suppress the generation of abnormal noise, etc. It is an issue of

  In order to solve such problems, the linear vibration motor according to the present invention has the following configuration.

  A frame, a mover resiliently supported by the frame in a uniaxial direction in a vibrating manner, a magnet fixed to one of the frame and the mover, and a coil fixed to the other. A drive source that causes the mover to oscillate in a single axial direction by energization of a drive signal to a coil, a shaft that guides vibration of the mover along the single axial direction, and a shaft that slidably supports the shaft A linear vibration motor comprising: a bearing, wherein at least a sliding contact portion between the shaft and the bearing has a non-circular cross section perpendicular to the uniaxial direction.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which showed the whole structure of the linear vibration motor which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing (sectional view) which showed the whole structure of the linear vibration motor which concerns on embodiment of this invention. It is an explanatory view showing a shaft and a bearing of a linear vibration motor concerning an embodiment of the present invention. It is explanatory drawing which showed the portable electronic device (portable information terminal) carrying the linear vibration motor which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the following different drawings indicate parts having the same functions, and redundant description in each drawing will be appropriately omitted. 1 and 2 show the overall configuration of a linear vibration motor according to an embodiment of the present invention. The X direction in each figure indicates the vibration direction (uniaxial direction), the Y direction indicates the width direction, and the Z direction indicates the thickness (height) direction.

  The linear vibration motor 1 includes a frame 2, a magnet 4 and a weight 7, and is fixed to the frame 2 on a movable element 10 elastically supported in a vibrating manner along the uniaxial direction, and a drive signal The coil 3 for oscillating the mover 10 back and forth in one axial direction by energization, the shaft 8 for guiding the vibration of the mover 10 in one axial direction, and the bearing 9 for slidably supporting the shaft 8 There is.

  In the illustrated example, the drive source (electromagnetic actuator) composed of the magnet 4 and the coil 3 is a moving source in which the magnet 4 is fixed to the mover 10 and the coil 3 is fixed to the frame (stator) 2 Although the example of the magnet system is shown, it may be a moving coil system in which the coil 3 is fixed to the mover 10 and the magnet 4 is fixed to the frame 2 conversely.

  In the illustrated example, the shaft 8 is fixed to the mover 10 and the bearing 9 is supported by the frame 2. Conversely, the bearing 9 is fixed to the mover 10 The shaft 9 may be fixed to the frame 2.

Hereinafter, the illustrated example will be described in detail.
The frame 2 only needs to have a frame configuration that can accommodate each part, but in the illustrated example, the frame 2 is provided with side walls 2B, 2C, 2D, and 2E erected around the rectangular bottom surface 2A. ing. Moreover, the frame 2 is equipped with the cover plate 2Q which covers the storage thing in the frame 2 as needed. The cover plate 2Q is formed in a rectangular plate shape attached to the upper end surfaces of the side walls 2B to 2E. The frame 2 can be formed by processing (such as pressing) a metal plate. In the illustrated example, the frame 2 has a thin shape in which the dimension in the thickness direction (Z direction in the figure) is smaller than the dimension in the width direction (Y direction in the figure) and the dimension in the vibration direction (X direction in the figure) is larger. It has a substantially rectangular parallelepiped shape (box shape).

  The coil 3 fixed to the frame 2 is obtained by winding a wire along the Y and Z directions around the magnet 4 with the magnetic pole oriented in the X direction, and one or both of the upper surface and the lower surface, Furthermore, the side surface is fixed to the inner surface of the frame 2 as needed. The coil 3 may be fixed to the frame 2 directly, or may be fixed to the frame 2 by winding the coil 3 around a coil bobbin.

  A plurality of flat rectangular magnet pieces 4A, 4B, 4C having a polarity along one axial direction (X direction in the drawing) are arranged such that the same poles face each other, and the spacers 4D, 4E are arranged. It is something which was joined and put in between. A reinforcing member 5 is fixed to the side surface of the magnet 4 to increase the rigidity of the magnet 4.

  In the movable element 10, in the illustrated example, the weight 7 is connected to both ends of the magnet 4 in the axial direction (X direction in the drawing). The weight portion 7 can be made of a metal material having a high specific gravity (for example, tungsten) or the like, and in the illustrated example, has a height in the Z direction larger than the thickness of the magnet 4 and a Y direction larger than the width of the magnet 4 It has a rectangular cross-sectional shape with a width of The weight 7 is connected to the magnet 4 via the connection member 11.

  The shaft 8 is fixed to the mover 10 in the example shown in FIGS. 1 and 2 and is slidably supported by a bearing 9 fixed to the frame 2. In this example, the shaft 8 is divided along one axial direction (X direction in the figure), one end of which is fixed to the weight portion 7 and the other end of which protrudes oppositely to form a free end. ing. The shaft 8 is disposed coaxially with the center of gravity axis of the mover 10, and guides the vibration of the mover 10 along one axial direction. The shaft 8 may be provided along one axial direction, and the central axes thereof may be arranged in parallel.

  The weight 7 includes a shaft support 7 B for supporting the shaft 8. The shaft support portion 7B is a portion recessed along the uniaxial direction from the end portion 7A of the weight portion 7, and the shaft 8 whose one end side is supported by the shaft support portion 7B is a support portion 2S on the bottom surface 2A of the frame 2. Is slidably supported along a uniaxial direction (X direction in the figure). At this time, the shaft support portion 7B of the weight portion 7 has a width sufficient to accommodate the bearing 9, and the bearing 9 enters the shaft support portion 7B to secure a large amplitude of the mover 10. There is.

  The elastic member 6, which elastically supports the mover 10 on the frame 2, is disposed non-coaxially with the shaft 8 along the uniaxial direction, and the mover is resilient to repel the driving force generated by the coil 3 and the magnet 4. Granted to 10. In the illustrated example, a coil spring extending and contracting in one axial direction (X direction) is used as the elastic member 6, and the two elastic members 6 on one side are placed between the weight 7 and the side walls 2B and 2C of the frame 2. It intervenes. In the illustrated example, the elastic member 6 is disposed parallel to the shaft 8. One end of the elastic member 6 is engaged with the support projection 2P provided on the side walls 2B and 2C of the frame 2, and the other end of the elastic member 6 is engaged with the support projection provided at the end 7A of the weight 7 It has been stopped.

  The linear vibration motor 1 comprises a coil 3 fixed to the frame 2 and a magnet 4 which is a part of the mover 10, and the coil 3 fixed to the frame 2 constitutes a driving source. By energizing the drive signal from the provided signal input unit 2A1, Lorentz force (driving force) along the uniaxial direction (X direction in the drawing) acts on the magnet 4. The drive signal supplied to the coil 3 is, for example, an alternating current of a resonant frequency (natural frequency) determined by the elastic coefficient of the elastic member 6 and the mass of the mover 10, and the driving force and the elastic member generated by this drive signal Due to the elastic repulsive force of 6, the mover 10 reciprocates in one axial direction.

  In such a linear vibration motor 1, as shown in FIG. 3, the shaft 8 and the bearing 9 have a non-circular cross section perpendicular to one axial direction (X direction in the drawing) at least at the sliding contact portion of the two. . In the illustrated example, the shaft 8 is formed with a flat portion 8a along one axial direction (X direction in the drawing), and the bearing 9 is also formed with a flat portion 9a slidingly contacting the flat portion 8a of the shaft 8 .

  According to the linear vibration motor 1 including the shaft 8 and the bearing 9 as described above, the non-circular shape of the shaft 8 and the bearing 9 suppresses the rotation of the mover 10 about one axis. For this reason, even if the cross section perpendicular to the uniaxial direction of the mover 10 has a thin cross-sectional shape as shown, the side portion of the mover 10 repeatedly hits the frame 2 while the mover 10 vibrates. It can be avoided. Thereby, the linear vibration motor 1 can obtain noiseless operation performance by suppressing generation of noise during vibration of the mover 10 while making the mover 10 thin and thin in cross-sectional shape.

  In addition, the cross-sectional shape of the shaft 8 and the bearing 9 is not limited to the example shown in FIG. The movable element 10 may have any shape as long as the movable element 10 does not rotate around the shaft 8.

  A lubricant is applied to the sliding contact portion between the shaft 8 and the bearing 9. By providing the flat portions 8a and 9a below the shaft 8 and the bearing 9 as shown in FIG. 3, a relatively large area of the flat portions 8a and 9a can receive a lubricant reservoir. By this, compared with the case of a circular cross section, the friction reduction effect of the lubricant can be enhanced, and the mover 10 can be vibrated more smoothly.

  As described above, the linear vibration motor 1 according to the embodiment of the present invention can obtain stable vibration by axially supporting the mover 10 with the shaft 8 to vibrate and, at the same time, resists damage at the time of drop impact Can be enhanced. Then, by making the cross section perpendicular to the uniaxial direction of the shaft 8 and the bearing 9 into a non-circular shape at least in the sliding contact portion between them, it is possible to suppress rotation or swinging around the uniaxial axis of the mover 10. As a result, it is possible to provide a linear vibration motor that is highly resistant to damage, can provide quietness during operation, and can be made thinner.

  FIG. 4 shows a portable information terminal 100 as an example of an electronic device equipped with the linear vibration motor 1 according to the embodiment of the present invention. The portable information terminal 100 including the linear vibration motor 1 capable of obtaining stable vibration and thinning and downsizing in the width direction is unlikely to generate abnormal noise at the start and end of operations such as an incoming call and an alarm function in the communication function. A stable vibration can be transmitted to the user.

  In addition, since the linear vibration motor 1 described in the embodiment has a compact shape in which each portion is accommodated in the rectangular parallelepiped frame 2 whose thickness is reduced, space efficiency can be achieved inside the thinned portable information terminal 100. It can be equipped. Further, since the linear vibration motor 1 has high impact resistance strength and high durability, it is possible to obtain the portable information terminal 100 having a long life and being hard to break down.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and changes in design etc. within the scope of the present invention are not limited. Are included in the present invention. In addition, the respective embodiments described above can be combined with each other by utilizing the techniques of each other unless there is a contradiction or a problem in particular in the purpose, the configuration, and the like.

1: Linear vibration motor,
2: Frame, 2A: bottom, 2A1: signal input section,
2B, 2C, 2D, 2E: side wall, 2S: support portion,
2P: support projection, 2Q: cover plate, 3: coil, 4: magnet,
4A, 4B, 4C: Magnet pieces, 4D, 4E: Spacers,
5: Reinforcement member, 6: Elastic member,
7: weight portion, 7A: end portion, 7A1: support projection, 7B: shaft support portion, 7C: hole,
8: shaft, 9: bearing, 8a, 9a: flat portion, 10: mover,
11: Connection member, 100: portable information terminal

Claims (4)

Frame body,
A mover resiliently and vibratably supported by the frame along a uniaxial direction;
A drive source including: a magnet fixed to one of the frame and the mover; and a coil fixed to the other, wherein the mover is reciprocated in the uniaxial direction by energization of a drive signal to the coil;
A shaft for guiding the vibration of the mover along the uniaxial direction;
And a bearing slidably supporting the shaft.
2. The linear vibration motor according to claim 1, wherein the shaft and the bearing have a non-circular cross section perpendicular to the uniaxial direction at least in a sliding contact portion of the both.   The linear vibration motor according to claim 1, wherein the shaft is fixed to the mover, and the bearing is supported by the frame.   The linear vibratory motor according to claim 1 or 2, wherein the movable element has a thin-walled cross-sectional shape in a cross section perpendicular to the uniaxial direction.   The electronic device provided with the linear vibration motor as described in any one of Claims 1-3.

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