JP2007143210A - Motor and lens drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor in which a movable body can be converged to a target speed or a target drive force quickly through a simple arrangement by utilizing an eddy current or a back-emf induced in a metal moving through a magnetic field, and to provide a lens drive. <P>SOLUTION: The lens drive 1 comprises a holder 5, a lens support 7 provided movably for the holder 5, a coil body 15 applied with a coil, a magnet 13, and a yoke 3 wherein the magnet 13 and the yoke 3 are secured to the holder 5 along the moving direction of the lens support 7, the coil body 15 is secured to the lens support 7 and arranged in the magnetic field of the magnet 13, and the lens support 7 is driven by an electromagnetic force generated by conducting the coil body 15. A ring-like nonmagnetic metal 12 generating an eddy current when the magnet 13 moves through the magnetic field of the magnet 13 is provided in the coil body 15 or the lens support 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor device that drives a moving body and a lens driving device that moves a lens in the optical axis direction.

  In general, eddy currents are generated in metal moving bodies that move in the magnetic field of magnets, and counter electromotive force is generated in coils, and it is known that forces that suppress the movement of metal moving bodies and coils act on them. Yes.

  On the other hand, in Patent Document 1, two metal moving bodies made of two magnetic bodies are provided opposite to each other, and the two metal moving bodies are relatively stopped when they are driven. Thus, it is disclosed that eddy current is prevented from being generated in a metal moving body.

JP 2002-51500 A

  On the other hand, when the moving body starts driving by supplying power to the motor coil, a driving force (electric power) larger than the target value is applied so as to exceed the inertial force when the moving body is stopped. There is a problem that a predetermined time is required until the body is stabilized at the target speed and the target driving force (convergence).

  Further, when the moving body is stopped after moving a predetermined amount, conventionally, the moving body is stopped by applying a frictional force or the like. However, there is a problem that it takes a predetermined time to stop (converge).

  On the other hand, it is known that a technique for preventing the generation of eddy currents as in the above-mentioned Patent Document 1 and measuring torque and the like using eddy currents are used for driving control of a moving body. There has never been a direct use of counter electromotive force.

  Therefore, the present invention uses a eddy current or a counter electromotive force generated in a metal moving in a magnetic field, thereby enabling a motor device to accelerate the convergence of a moving body to a target speed or a target driving force with a simple configuration. And it aims at provision of a lens drive device.

  The invention described in claim 1 includes a holder, a movable body provided so as to be movable with respect to the holder, a coil body around which a coil is wound, a magnet, and a yoke, and the magnet and the yoke move the movable body. In the motor device that is fixed to the holder along the direction, the coil body is fixed to the moving body and arranged in the magnetic field of the magnet, and the moving body is driven by electromagnetic force generated by energizing the coil body. The body or the moving body is provided with a non-magnetic metal that generates an eddy current when moving in a magnetic field of a magnet in a ring shape.

  The invention according to claim 2 includes a holder, a movable body provided movably with respect to the holder, a coil body around which a coil is wound, a magnet, and a yoke, and the magnet and the yoke move the movable body. In the motor device that is fixed to the holder along the direction, the coil body is fixed to the moving body and arranged in the magnetic field of the magnet, and the moving body is driven by electromagnetic force generated by energizing the coil body. The body or the moving body is characterized in that a short-circuit coil that generates a counter electromotive force when moving in a magnetic field of a magnet is provided in a ring shape.

  A third aspect of the present invention includes a holder, a lens support provided so as to be movable with respect to the holder, a coil body wound with a coil, a magnet, and a yoke, and the magnet and the yoke are the lens support. The lens body is fixed to the holder along the moving direction of the lens, the coil body is fixed to the lens support body and disposed in the magnetic field of the magnet, and the lens body is driven by electromagnetic force generated by energizing the coil body. In the driving apparatus, the coil body or the lens support is provided with a non-magnetic metal that generates an eddy current when moving in a magnetic field of a magnet in a ring shape.

  The invention according to claim 4 includes a holder, a lens support provided movably with respect to the holder, a coil body wound with a coil, a magnet, and a yoke, and the magnet and the yoke are the lens support. The lens body is fixed to the holder along the moving direction of the lens, the coil body is fixed to the lens support body and disposed in the magnetic field of the magnet, and the lens body is driven by electromagnetic force generated by energizing the coil body. In the driving apparatus, the coil body or the lens support body is provided with a short-circuit coil that generates a back electromotive force when moving in a magnetic field of a magnet in a ring shape.

  According to the first aspect of the present invention, when power is supplied to the coil of the coil body, the coil body moves within the magnetic field of the magnet. However, a ring-shaped nonmagnetic metal is present on the coil body or the moving body within the magnetic field. Therefore, an eddy current flowing along the ring is generated in the ring-shaped nonmagnetic metal. Since the force (braking force) in the direction opposite to the moving direction of the moving body acts on the moving body due to the eddy current, the braking force in the direction to suppress the driving force of the moving body acts and converges to the target speed or target driving force. The responsiveness of moving body control is excellent.

  Since only the nonmagnetic metal is provided in a ring shape, the configuration is simple and the manufacture is easy.

  A non-magnetic metal is sufficient in the form of a foil. If a foil is used, it is difficult to affect the weight of the motor device and it is easy to mount.

  As the nonmagnetic metal, aluminum, copper, or the like can be used.

  According to the second aspect of the present invention, since the back electromotive force is generated in the short-circuiting coil due to the movement of the moving body as in the first aspect of the invention, the braking force in the direction to suppress the driving force of the moving body is applied. Thus, the convergence to the target speed and the target driving force can be accelerated, and the response of the moving body control is excellent.

  Further, since the coil is used, the configuration is simple, the weight of the motor device is hardly affected, and the mounting is easy.

  According to the third aspect of the present invention, since the eddy current is generated in the ring-shaped non-magnetic metal by the movement of the lens support as in the case of the first aspect, the driving force of the lens support is reduced. The braking force in the restraining direction can act to accelerate the convergence to the target speed or the target driving force, and the response of the driving control of the lens support is excellent.

  Further, if a foil-like nonmagnetic metal is used, it is difficult to affect the weight of the motor device and mounting is easy.

  In particular, in a small camera, the responsiveness of drive control can be enhanced without affecting the dimensions and parts of the lens drive device.

  According to the invention described in claim 4, as in the invention described in claim 3, back electromotive force is generated in the ring-shaped short-circuit coil by the movement of the lens support, and the braking force acts on the lens support. Therefore, the convergence to the target speed and the target driving force during driving of the lens support can be accelerated, the response of the drive control of the lens support is excellent, the configuration is simple, and the manufacture is easy.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. First, the first embodiment of the present invention will be described with reference to FIGS. 1 is a longitudinal sectional view of the lens driving device according to the first embodiment, FIG. 2 is a longitudinal sectional view when the lens driving device according to the first embodiment is driven, and FIG. 3 is a first embodiment. FIG. 4 is a graph showing the relationship between the force acting on the lens support and time.

  A lens driving device (motor device) 1 according to the first embodiment is a lens driving device for an autofocus small camera incorporated in a mobile phone.

  The lens driving device 1 includes a holder 5, a yoke 3, a lens support body (moving body) 7 provided so as to be movable with respect to the holder 5, a coil body 15 around which a coil is wound, a magnet 13, The holder 5 is fitted and fixed to the base 6.

  The yoke 3 has a substantially U-shaped longitudinal section, and a magnet 13 is disposed inside the U-shape, and a coil body 15 is disposed on the inner peripheral side of the magnet 13 inside the U-shape. The magnet 13 is fixed to the holder 5 via a rear spacer 17 (see FIG. 3). The coil body 15 is fixed to the outer periphery of the lens support 7, and the outer periphery of the lens support 7 enters the yoke 3, and the outer periphery of the lens support 7 moves through the U-shaped gap of the yoke 3. It is supposed to do.

  The lens support 7 has a substantially cylindrical shape, in which a lens 20 is housed, and is attached to the inner peripheral side of the yoke 3 so as to be movable along the optical axis.

  The nonmagnetic metal 12 is an aluminum metal foil and is affixed over substantially the entire inner peripheral surface of the coil body 15 provided in an annular shape. The non-magnetic metal 12 has a ring shape and forms a short circuit.

  The lens support 7 is supported by the front spring 9 and the rear spring 11 so as to be movable with respect to the holder 5.

  As shown in FIG. 3, the front spring 9 is a substantially annular leaf spring, the inner peripheral end 9 a is sandwiched and fixed between the lens support 7 and the cap 24, and the outer peripheral end 9 b is the yoke 3. Between the outer peripheral side end portion 9b and the yoke 3, a front spacer 21 is interposed.

  The rear spring 11 has substantially the same shape as the front spring 9 and is a substantially annular leaf spring. The inner peripheral end 11 a of the rear spring 11 is fixed to the rear end of the lens support 7, and the outer peripheral end 11 b is fixed between the base portion of the holder 5 and the rear spacer 17.

  Next, the assembly, operation, and effect of the lens driving device 1 according to the present embodiment will be described. A non-magnetic metal 12 provided in a ring shape in advance along the inner peripheral surface is pasted on the coil body 15. Then, the inner peripheral end 11 a of the rear spring 11 is attached to the lens support 7, the magnet 13 and the coil body 15 fixed to the lens support 7 are disposed inside the yoke 3, and the base of the holder 5 is placed. It is assembled to the part via the rear spacer 17. Thereafter, the inner peripheral end 9 a of the front spring 9 is placed between the front spacer 21 and the yoke 3 and fixed with the cap 24, and the frame 23 is attached to the holder 5, and the outer peripheral end 9 b is fixed with the frame 23. Fix it. Then, the holder 5 assembled with each component is fitted and fixed to the base 6.

  When power is supplied to the coil body 15 during driving, an electromagnetic force is generated in the coil body 15 in the magnetic field of the magnet 13 and the lens support 7 moves in the optical axis direction. Then, when the driving force of the lens support 7 and the urging force of the front spring 9 and the rear spring 11 are balanced, the lens support 7 stops (see FIG. 2).

  When the coil body 15 is energized at the start of driving, it is necessary to apply a driving force that exceeds the inertial force of the lens support 7 to maintain the stopped state, so that it is necessary for balancing with the springs 9 and 11 at the target position. Energize with larger power than normal power. Therefore, immediately after the coil body 15 is energized, a larger driving force Fa is generated than when the lens support 7 is balanced, but at the same time, the ring-shaped non-magnetic metal 12 moves in the magnetic field of the magnet 13. In the nonmagnetic metal 12, an eddy current flowing along the ring is generated. A braking force Fb in the direction opposite to the driving direction acts on the lens support 7 by the eddy current generated in the nonmagnetic metal.

  For this reason, as shown in FIG. 4, the force acting on the lens support 7 is a target that balances the urging force of the front spring 9 and the rear spring 11 due to the interaction between the driving force Fa and the braking force Fb. It converges to the driving force Fm.

  As for the relationship between the driving force Fa and the braking force Fb, the braking force Fb increases as the driving force Fa increases and the moving speed of the lens support 7 increases, and the braking force increases as the moving speed of the lens support 7 decreases. Fb also decreases.

  In the present embodiment, since the ring-shaped nonmagnetic metal 12 is provided, a braking force in a direction to suppress the driving force due to the driving of the lens support 7 acts to accelerate the convergence to the target driving force Fm. The response in driving control of the lens support 7 is excellent.

  Since only the non-magnetic metal 12 is affixed to the inner peripheral surface of the coil body 15, the configuration is simple and the manufacture is easy.

  In particular, since the nonmagnetic metal 12 is foil-like, it is lightweight, hardly affects the weight of the lens driving device, and is easy to mount.

  Next, a second embodiment of the present invention will be described with reference to FIG. 5. In the embodiment described below, the same parts as those in the first embodiment described above are the same. The description of the portion is omitted by attaching the reference numeral, and the following description will mainly explain differences from the first embodiment.

  The second embodiment is different from the above-described nonmagnetic metal 12 in that a short-circuit coil 31 is provided in a ring shape.

  The short circuit coil 31 is wound around the inner peripheral surface of the coil body 15, and one end and the other end of the short circuit coil 31 are electrically connected to each other to form a short circuit. In the present embodiment, the short-circuit coil 31 has a two-layer structure, and the coil is wound about 50 turns in total.

  In the second embodiment, the back electromotive force is generated in the short-circuit coil 31 moving in the magnetic field, and the braking force Fb in the direction opposite to the driving force Fa is generated. Obtainable.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

  For example, the nonmagnetic metal 12 and the short-circuit coil 31 may be provided on the outer peripheral surface of the coil body 15, or may be provided on the outer peripheral portion of the lens support 7 located in the yoke 3.

  The thickness, size, number of turns, etc. of the nonmagnetic metal 12 and the short-circuit coil 31 can be changed according to the magnitude of the braking force to be applied to the lens support 7.

  The present invention is not limited to the lens driving device 1 and can also be used for a motor device that controls driving of a moving body such as a stepping motor.

It is a longitudinal cross-sectional view of the lens drive device concerning 1st Embodiment. It is a longitudinal cross-sectional view when the lens drive device concerning 1st Embodiment is driven. It is a disassembled perspective view of the lens drive device concerning a 1st embodiment. It is a graph which shows the relationship between the force which acts on a lens support body, and time. It is a longitudinal cross-sectional view of the lens drive device concerning 2nd Embodiment.

1 Lens drive device (motor device)
3 Yoke 5 Holder 7 Lens support (moving body)
12 Non-magnetic metal 13 Magnet 15 Coil body 31 Short-circuit coil

Claims (4)

  A holder, a movable body provided movably with respect to the holder, a coil body wound with a coil, a magnet, and a yoke are provided, and the magnet and the yoke are fixed to the holder along the moving direction of the movable body. The coil body is fixed to the moving body and arranged in the magnetic field of the magnet. In a motor device that drives the moving body by electromagnetic force generated by energizing the coil body, the coil body or the moving body has a magnetic field of the magnet. A motor device, characterized in that a non-magnetic metal that generates an eddy current when moving inside is provided in a ring shape.   A holder, a movable body provided movably with respect to the holder, a coil body wound with a coil, a magnet, and a yoke are provided, and the magnet and the yoke are fixed to the holder along the moving direction of the movable body. The coil body is fixed to the moving body and arranged in the magnetic field of the magnet. In a motor device that drives the moving body by electromagnetic force generated by energizing the coil body, the coil body or the moving body has a magnetic field of the magnet. A motor device characterized in that a short-circuiting coil that generates a counter electromotive force when moving inside is provided in a ring shape.   A holder, a lens support provided so as to be movable with respect to the holder, a coil body wound with a coil, a magnet, and a yoke are provided. The magnet and the yoke are fixed to the holder along the moving direction of the lens support. In the lens driving device for driving the lens support by electromagnetic force generated by energizing the coil body, the coil body is fixed to the lens support and disposed in the magnetic field of the magnet. A lens driving device characterized in that the body is provided with a ring of a non-magnetic metal that generates an eddy current when moving in a magnetic field of a magnet. A holder, a lens support provided movably with respect to the holder, a coil body wound with a coil, a magnet, and a yoke are provided, and the magnet and the yoke are fixed to the holder along the moving direction of the lens support. In the lens driving device for driving the lens support by the electromagnetic force generated by energizing the coil body, the coil body is fixed to the lens support and disposed in the magnetic field of the magnet. A lens driving device characterized in that the body is provided with a short-circuit coil in a ring shape that generates a back electromotive force when it moves in the magnetic field of a magnet.

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