VOICE COIL MOTOR AND DRIVING METHOD THEREOF

• US 20140192428A1
• Filed: 03/11/2014
• Published: 07/10/2014
• Est. Priority Date: 11/02/2010
• Status: Active Grant

• Current Assignee: LG Innotek Company Limited (LG Corporation)
• Original Assignee: LG Innotek Company Limited (LG Corporation)
• Inventors: PARK, Sangok
• Granted Patent: US 9,429,734 B2
• Time in Patent Office: Days
• US Class Current: 359/824
• CPC Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• CPC Class Codes: G02B 7/09 adapted for automatic focusing or varying magnification
• CPC Class Codes: H02K 33/18 with coil systems moving upon intermittent or reversed energisation thereof by interaction with a fixed field system, e.g. permanent magnets
• CPC Class Codes: H02K 41/0356 moving along a straight path
• CPC Class Codes: H02P 25/034 Voice coil motors voice coil motors driven by DC H02P7/025

Abstract

A voice coil motor (VCM) is disclosed, the VCM including: a stator including a magnet generating a first electromagnetic field; a mover including a bobbin formed with a hollow hole through which light passes and a coil formed on a periphery of the bobbin that generates a second electromagnetic field responsive to the first electromagnetic field; a base fixed at the stator and formed with an opening through which the light passes; and at least one elastic member elastically supporting the bobbin and forming a gap between the bobbin and the base when the coil is not applied with a current.

Claims

1. A voice coil motor comprising:

a stator including a magnet generating a first magnetic field;

a mover including a bobbin with an opening formed therein for transmitting light therethrough and a coil block disposed on an outer circumference surface of the bobbin and for generating a second magnetic field that interacts with the first magnetic field;

a base for fixing the stator and having an opening for transmitting the light; and

at least one elastic member that flexibly supports the bobbin and allows the bobbin and the base to be spaced apart from each other when current is not supplied to the coil block, wherein;

the elastic member comprises two electrically insulated portions,

one of the two portions is electrically connected to one end of a wire constituting a coil of the coil block,

the other one of the two portions is electrically connected to the other one opposite to the one end of the wire, and

the bobbin supported by the elastic member is driven in any one of a first direction away from the base due to ascending force generated by the first and second magnetic fields and a second direction toward the base due to descending force generated by the first and second magnetic fields.

2. The voice coil motor of claim 1, wherein:

driving of the bobbin in any one of the first direction and the second direction comprises moving the bobbin to a reference location to align the bobbin; and

forward current is supplied to the coil when the bobbin is driven in the first direction, and reverse current flowing in an opposite direction to the forward current is supplied to the coil when the bobbin is driven in the second direction.

3. The voice coil motor of claim 1, wherein the bobbin is driven in any one of the first direction and the second direction by adjusting a voltage difference between opposite ends of the coil.

4. A voice coil motor comprising:

a stator including a magnet generating a first magnetic field;

a mover including a bobbin with an opening formed therein for transmitting light therethrough and a coil block disposed on an outer circumference surface of the bobbin and for generating a second magnetic field that interacts with the first magnetic field;

a base for fixing the stator and having an opening for transmitting the light; and

at least one elastic member that flexibly supports the bobbin and allows the bobbin and the base to be spaced apart from each other when current is not supplied to the coil block, wherein the at least one elastic member comprises two electrically insulated portions, one of the two portions is electrically connected to one end of a wire constituting a coil of the coil block, and the other one of the two portions is electrically connected to the other one opposite to the one end of the wire; and

a driving module including a controller configured to generate each of an ascending control signal for ascending the bobbin and a descending control signal for descending the bobbin, and a current supplying unit configured to supply one of forward current and revere current to the coil block in response to the ascending and descending control signals of the controller.

5. The voice coil motor of claim 4, wherein:

the current supplying unit comprises a first circuit in which first and second switch devices are connected in series, and a second circuit in which to third and fourth switch devices are connected in series;

the first and second circuits are electrically connected in parallel to a power source;

a first end of the coil block is connected between the first and second switch devices; and

a second end of the coil block is connected between the third and fourth switch devices.

6. The voice coil motor of claim 5, wherein:

the ascending control signal is applied to the first and fourth switch devices to supply the forward current to the coil block; and

the descending control signal is applied to the second and third switch devices to supply the reverse current to the coil block.

7. A method of driving a voice coil motor, the method comprising:

aligning a bobbin having a lens therein and flexibly supported by an elastic member at a location spaced apart from a base to which a magnet is fixed by supplying first current to a coil wound on the bobbin to move the bobbin to a reference location;

spacing the bobbin apart from the reference location by reducing an amount of the first current supplied to the coil or supplying second current flowing in an opposite direction to the first current; and

stopping the bobbin to a location corresponding to an optimal focus by maintaining an amount of the first current or the second current when the optimal focus is formed between the lens and an image sensor module disposed below the bobbin.

8. The method of claim 7, wherein the reference location is any one of an upper surface of the base and an internal lateral surface of a cover can for covering the bobbin.

9. The method of claim 7, wherein the spacing the bobbin from the reference location comprises continuously increasing the first current or the second current.

10. The method of claim 7, wherein the stopping of the bobbin to the location corresponding to the optimal focus comprises:

moving the bobbin to be deviated from the location of the optimal focus; and

resupplying the first current to the coil or reducing the amount of the second current to restore the bobbin to the location of the optimal focus.

11. A method of driving a voice coil motor, the method comprising:

aligning a bobbin having a lens therein and flexibly supported by an elastic member at a location spaced apart from a base to which a magnet is fixed by supplying first current to a coil wound on the bobbin to move the bobbin to a reference location;

calculating data for forming an optimal focus between a lens and an image sensor module based on an object; and

moving the bobbin from the reference location based on the data by reducing an amount of the first current or supplying second current flowing in an opposite direction to the first current to the coil in response to the data.

12. The method of claim 11, wherein the first current or the second current has constant intensity.