KR20180082384A - Voice coil motor and driving method thereof - Google Patents

Abstract

The present invention relates to a voice coil motor which is driven bi-directionally with respect to a reference position and driven at low current and low power consumption, and relates to a driving method thereof. According to the present invention, the voice coil motor comprises: a stator which includes a coil block and a housing for fixing the coil block; a rotor which is disposed in the coil block and includes a bobbin having a lens fixed to the inside thereof and a magnet disposed in the bobbin to face the coil block; a base which has the housing fixated thereto and includes an opening formed in a position corresponding to the lens, and a bobbin accommodation groove formed on an upper surface that faces the bobbin, wherein the bobbin accommodation groove accommodates a lower surface of the bobbin; and a lower elastic member which is fixated to the bobbin and the base so that a gap is formed between the lower surface of the bobbin and the bottom surface formed by the bobbin accommodation groove regardless of posture of the rotor when a driving signal is not applied to the coil block.

Description

[0001] Description [0002] VOICE COIL MOTOR AND DRIVING METHOD THEREOF [0002]

The present invention relates to a voice coil motor driven in both directions from a reference position and operated with low current and low power consumption, and a driving method thereof.

In recent years, mobile phones including a compact digital camera have been developed.

Conventionally, in the case of a miniature digital camera applied to a mobile phone or the like, the interval between the image sensor and the lens for changing the external light into a digital image or a digital image can not be adjusted. Recently, a voice coil motor The same lens driving device has been developed, so that it is possible to obtain an improved digital image or a digital image in a very small digital camera.

In general, a voice coil motor is equipped with a lens therein, and a bobbin disposed on the base moves upward from the base to adjust the distance between the lens and the image sensor disposed on the rear surface of the base.

When the voice coil motor is not operated, the bobbin is always brought into contact with the base by the elastic force of the leaf spring. That is, the bobbin of the conventional voice coil motor is driven in one direction toward the upper portion with respect to the base.

 In order to drive the voice coil motor by driving the voice coil motor only in one direction, a driving force greater than the self-weight of the bobbin and the elastic force of the leaf spring is required, which increases the power consumption of the voice coil motor.

Further, in order to drive the voice coil motor, a driving force greater than the self-weight of the bobbin and the elastic force of the leaf spring is required, which increases the size of the coil wound around the magnet or the bobbin, thereby increasing the overall size of the voice coil motor.

Further, when the shape of the leaf spring is deformed, there is a problem that the focus between the lens and the image sensor is not precisely performed and the image quality is greatly lowered.

The present invention provides a voice coil motor suitable for driving a mover with a smaller current and a method of driving the same.

The technical object of the present invention is not limited to the above-mentioned technical objects and other technical objects which are not mentioned can be clearly understood by those skilled in the art from the following description will be.

In one embodiment, the voice coil motor includes a stator including a coil block and a housing for securing the coil block; A bobbin disposed inside the coil block and having a lens fixed therein, and a magnet disposed on the bobbin so as to face the coil block; A base fixed to the housing and having an opening at a position corresponding to the lens and having a bobbin receiving groove for receiving a lower surface of the bobbin on an upper surface facing the bobbin; And a lower elastic member fixed to the bobbin and the base so that a gap is formed between a lower surface of the bobbin and a bottom surface formed by the bobbin receiving groove when the drive signal is not applied to the coil block, Member.

In one embodiment, the voice coil motor includes a stator including a coil block and a housing for securing the coil block; A bobbin disposed inside the coil block and having a lens fixed therein, and a magnet disposed on the bobbin so as to face the coil block; A base fixed to the housing and having an opening at a position corresponding to the lens and having a bobbin receiving groove for receiving a lower surface of the bobbin on an upper surface facing the bobbin; And a lower elastic member fixed to the bobbin and the base such that a gap is formed between a lower surface of the bobbin and a bottom surface formed by the bobbin receiving groove, the bobbin supported by the lower elastic member is inserted into the coil block And a second direction that is moved away from the base by a first force generated by the magnet and a second direction that is closer to the base by the bobbin receiving groove.

In one embodiment, a method of driving a voice coil motor includes a base having a bobbin receiving groove formed therein, a mover disposed on the bobbin receiving groove and disposed above the bobbin receiving groove, a mover including a magnet, A voice coil motor comprising: a stator including a coil block; and an elastic member for floating the mover on the bobbin receiving groove, wherein the bobbin is moved to a reference position by applying an initial driving signal to the coil block, Aligning; Moving the bobbin from the reference position to a focus position by applying a driving current to the coil block, the level of which is increased or decreased; And stopping the bobbin at a position corresponding to the optimum focus by keeping the level of the driving current constant when an optimum focus is formed between the lens and the image sensor module.

In one embodiment, a method of driving a voice coil motor includes a base having a bobbin receiving groove formed therein, a mover disposed on the bobbin receiving groove and disposed above the bobbin receiving groove, a mover including a magnet, A stator including a coil block and an elastic member for floating the mover on the bobbin receiving groove, and aligning the bobbin by moving the bobbin to a reference position by applying a reference current to the coil block; Moving the bobbin from the reference position to a focus position by applying a driving current to the coil block, the level of which is increased or decreased; And stopping the bobbin at a position corresponding to the optimum focus by keeping the level of the driving current constant when an optimum focus is formed between the lens and the image sensor module.

According to the voice coil motor and the driving method therefor of the present invention, the bobbin on which the lens is mounted is floated from the bobbin receiving groove formed on the upper surface of the base on which the image sensor is mounted, and a positive current or a reverse current is applied to the coil block, Driving the voice coil motor to a low current and power consumption can be reduced and the focus between the lens and the image sensor can be adjusted in a shorter period of time by driving the mover including the bobbin in a direction away from the base or in a direction approaching the base, It is possible to reduce contact noise due to driving.

1 is an exploded perspective view of a voice coil motor according to an embodiment of the present invention.
Fig. 2 is an assembled sectional view of Fig. 1. Fig.
3 is a cross-sectional view conceptually showing the voice coil motor shown in Fig.
4 is a graph showing the relationship between the amount of drive current and the amount of movement for driving the voice coil motor shown in Fig.
5 is a block diagram showing a driving circuit for raising or lowering the mover of the voice coil motor of Fig.
6 and 7 are block diagrams showing that a forward current or a reverse current is applied to the coil block by the driving circuit of FIG.
FIGS. 8 and 9 are graphs for explaining the driving method of the voice coil motor shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The sizes and shapes of the components shown in the drawings may be exaggerated for clarity and convenience. In addition, terms defined in consideration of the configuration and operation of the present invention may be changed according to the intention or custom of the user, the operator. The definitions of these terms should be interpreted based on the contents of the present specification and meanings and concepts in accordance with the technical idea of the present invention.

1 is an exploded perspective view of a voice coil motor according to an embodiment of the present invention. Fig. 2 is an assembled sectional view of Fig. 1. Fig.

1 and 2, the voice coil motor 600 includes a stator 100, a mover 200, a base 300, and a lower elastic member 400. In addition, the voice coil motor 600 may include a cover can 500.

The stator 100 includes a coil block 120 and a housing 150. The stator 100 generates a magnetic field for driving the mover 200, which will be described later.

The coil block 120 is formed, for example, by winding a long electric wire insulated by an insulating resin into a cylindrical shape. When a voltage having a voltage difference is applied to the coil block 120 formed by winding the long wires insulated by the insulating resin, a magnetic field is generated from the coil block 120, and the direction of the magnetic field flows in the coil block 120 It is changed according to the direction of the current.

The housing 150 fixes the coil block 120. The housing 150 includes, for example, a housing body 152 and pillars 154.

The housing body 152 is formed, for example, in the shape of a rectangular plate, and an opening 153 is formed at the center of the housing body 152 to expose a lens mounted on a bobbin to be described later.

On the upper surface of the housing body 152, a plurality of engaging bosses 156 for fixing the upper elastic member to be described later are formed.

The pillars 154 project from the four corners of the lower surface of the housing body 152 facing the base 300, respectively. The inner surface of the coil block 120 is fixed to the outer circumferential surface of the pillars 154. The pillars 154 may be coupled to the upper surface of the base 300 to be described later.

The coil block 120 may be attached to the pillars 154 of the housing 150 by an adhesive or the like or may be wound directly on the pillars 154 of the housing 150, .

The mover 200 includes a bobbin 210 and a magnet 250.

A cylindrical lens 205 is fixed inside the bobbin 210. The mover 200 moves with respect to the stator 100 to adjust the distance between the image sensor and the lens 205 disposed on the lower surface of the base 300 to be described later.

The bobbin 210 is formed, for example, in a hollow cylindrical shape, and a thread for fixing the lens 205 is formed on the inner circumferential surface of the bobbin 210.

On the outer circumferential surface of the bobbin 210, flat magnet fixing portions 215 for fixing a plurality of magnets 250 are formed. For example, four magnet fixing portions 215 are formed at equal intervals on the outer peripheral surface of the bobbin 210, for example.

The magnets 250 are formed in a plate shape and the magnets 250 are fixed to the respective magnet fixing portions 215 formed on the outer peripheral surface of the bobbin 210. Each of the magnets 250 may be attached to the magnet fixing portion 215 by an adhesive or the like.

Each of the magnets 250 is arranged to face the coil block 120 of the stator 100.

The base 300 is formed, for example, in the shape of a rectangular parallelepiped plate, and serves to fix the stator 100.

The base 300 is formed, for example, in the shape of a rectangular parallelepiped plate, and serves to fix the stator 100.

An opening 310 through which the light passing through the lens 205 incorporated in the bobbin 210 of the mover 200 passes is formed at the center of the base 300.

Coupling pillars 325 are formed at the four corners of the upper surface 320 of the base 300 formed in a plate shape and the coupling pillars 325 are formed by coupling the cover can 500 and the base 300, .

An IR filter 301 and an image sensor (not shown) are fixed to the rear surface of the base 300 to generate an image corresponding to light passing through the lens 205 of the bobbin 210.

The upper surface 320 of the base 300 has a bobbin receiving groove 330 recessed from the upper surface 320. The bobbin receiving groove 330 serves to receive the lower end of the bobbin 210.

The bobbin receiving grooves 330 are formed to be larger than the plane of the bobbin 210 and the bobbin receiving grooves 330 can partially overlap the bobbin 210 and the base 300.

In one embodiment of the present invention, the depth of the bobbin receiving groove 330 is formed in consideration of the stroke length of the mover 200.

On the bottom surface 335 of the bobbin 210 formed by the bobbin receiving groove 330 is disposed a shock absorbing member 350 formed along the opening 310 of the base 300. The shock absorbing member 350 absorbs impacts due to collision, for example, of the bobbin 210 and the bottom surface 335 of the base 300.

In one embodiment of the present invention, the shock-absorbing member 350 may include any one of a sponge, a synthetic resin having elasticity, and rubber, and the shock-absorbing member 350 may be formed in an annular plate shape having a thin thickness .

The lower elastic member 400 elastically supports the bobbin 210 of the mover 200 and the lower elastic member 400 is fixed to the bottom of the bobbin 210 of the mover 200, To float on top of the groove 330.

That is, the lower elastic member 400 is fixed to the lower surface of the bobbin 210 and the upper surface 320 of the base 300, regardless of the posture of the bobbin 210, when no current is applied to the coil block 120. [ A gap is formed between the bottom surface 335 formed by the receiving groove 330.

Here, the posture of the bobbin 210 means that the lens of the bobbin 210 is directed downward, the lens of the bobbin 210 is directed upward, or the lens of the bobbin 210 is disposed in parallel with the ground.

The lower elastic member 400 includes an inner lower elastic portion 410, an outer lower elastic portion 420, and a connection lower elastic portion 430.

The inner lower elastic portion 410 is formed, for example, in the shape of an annular ring, and the inner lower elastic portion 410 is coupled to the lower surface of the bobbin 210. The inner lower elastic portion 410 is joined to the lower surface of the bobbin 210 by, for example, adhesive or heat fusion.

The inner lower elastic portion 410 is also inserted into the bobbin receiving groove 330 of the base 300 because the inner lower elastic portion 410 is coupled to the lower surface of the bobbin 210.

The outer lower elastic portion 420 is disposed on the outer side of the inner lower elastic portion 410 and the outer lower elastic portion 420 is formed in a rectangular frame shape.

The outer lower elastic portion 420 is formed to be larger than the bobbin receiving groove 330 of the base 300 so that the outer lower elastic portion 420 is disposed on the upper surface 320 of the base 300. The outer lower elastic portion 420 may be fixed on the upper surface 320 of the base 300 by the pillars 154 of the housing 150 of the stator 100, for example.

The connection lower elastic portion 430 elastically connects the inner lower elastic portion 410 and the outer lower elastic portion 420 to each other and the inner lower elastic portion 410 is elastically supported by the connection lower elastic portion 430 do.

In one embodiment of the present invention, the bobbin 210 is floated on top of the bobbin receiving groove 330 of the base 300 by the lower elastic member 400.

The inner lower elastic portion 410 is spaced apart from the bottom surface 335 formed by the bobbin receiving groove 330 and the inner lower elastic portion 410 and the outer lower elastic portion 410 are spaced apart from each other when the drive signal is not applied to the coil block 120. [ The lower elastic portion 420 and the connection lower elastic portion 430 may be disposed on the same plane. Alternatively, when no driving signal is applied to the coil block 120, the inner lower elastic portion 410 may be disposed at a somewhat lower position than the outer lower elastic portion 420.

When the concave bobbin receiving groove 330 is formed on the upper surface 320 of the base 300, the bobbin receiving groove 330 is used while reducing the overall volume of the voice coil motor 600 So that the mover 200 can be driven in the direction away from the base 300 or in the direction in which the mover 200 approaches the base 300. [

That is, when the mover 200 is separated from the upper surface 320 of the lower base 300, the mover 200 moves toward the base 300 by changing the direction of the current applied to the coil block 120 Downward or away from the base 300, respectively.

The upper elastic member 450 is coupled to the coupling boss 156 formed on the upper surface of the housing body 152 of the housing 150 of the stator 100.

The upper elastic member 450 includes an inner upper elastic portion 451, an outer upper elastic portion 452, and a connecting upper elastic portion 453.

The inner upper elastic portion 451 is coupled to the upper surface of the bobbin 210 and the outer upper elastic portion 452 is disposed on the upper surface of the housing body 152. The connection upper elastic portion 453 connects the outer and inner upper elastic portions 451 and 452.

A coupling hole 455 is formed in the outer upper elastic part 452 disposed on the upper surface of the housing body 152 so as to engage with the coupling boss 156 formed on the upper surface of the housing body 152.

Referring again to FIG. 1, the voice coil motor 600 may further include a cover can 500.

The cover can 500 includes an upper plate 510 having an opening exposing the lens 205 of the mover 200 and a side plate 520 extending in the direction toward the base 300 from the edge of the upper plate 510 And the side plate 520 is engaged with the side surface of the base 300.

2, the bobbin 210 of the mover 200 according to an embodiment of the present invention is fixed to the upper surface 320 of the base 300 by a force generated from the coil block 120 and the magnet 250 In a first direction FD away from the first direction FD and in a second direction SD toward the bottom surface of the bobbin receiving groove 330 of the base 300 in the direction opposite to the first direction FD.

The bobbin 210 of the mover 200 is driven in the first direction FD when a forward current is applied to the coil block 120 and the bobbin 210 is driven in the first direction FD when the coil block 120 ) Is driven in a second direction (SD) when a reverse current that is opposite to the forward current is applied.

At this time, the forward current or the reverse current applied to the coil block 120 can be implemented by adjusting a voltage difference applied to both ends of the coil block 120, and the voltage difference can be implemented by, for example, a PWM circuit.

3 is a cross-sectional view conceptually showing the voice coil motor shown in Fig. 4 is a graph showing the relationship between the amount of drive current and the amount of movement for driving the voice coil motor shown in Fig.

1, 3 and 4, the mover 200 including the bobbin 210 and the magnet 250 is fixed by the lower elastic member 400 and the upper elastic member 450, When the current is not applied to the coil block 120 due to the elastic force of the upper elastic members 400 and 450, the mover 200 is positioned at a position spaced apart from the bottom surface 335 of the bobbin receiving groove 330 of the base 300 .

That is, in an embodiment of the present invention, the bobbin 210, which is elastically fixed to the lower and upper elastic members 400 and 450, is floated by the bobbin receiving groove 330, Direction in the second direction SD toward the top surface 320 of the base 300 or in the first direction FD away from the top surface 320 of the base 300 according to the direction of the current applied to the base 300 .

A positive current is applied to the coil block 120 to widen the gap between the image sensor disposed at the lower portion of the base 300 and the lens included in the mover 200, Lt; / RTI >

The first magnetic field generated from the coil block 120 acts on the second magnetic field generated from the magnet 250 mounted on the bobbin 210 of the mover 200 to move the mover 200 to the upper In a first direction (FD) toward the second direction (FD). The upward force is increased in proportion to the intensity of the forward current applied to the coil block 120. [

The upper and lower elastic members 400 and 450 of the voice coil motor 600 according to an embodiment of the present invention are configured to move the mover 200 in a direction toward the base 300 when no current is applied to the coil block 120 The mover 200 begins to rise in the first direction FD away from the upper surface of the base 300 as soon as a forward current is applied to the coil block 120. [

Hereinafter, in the graph of Fig. 4, the current in the region where the X-axis is positive is defined as the "forward current ", and the current in the region where the X-axis is negative in the graph of Fig. 4 is defined as the" reverse current ".

The mover 200 of the voice coil motor 600 according to an embodiment of the present invention may be configured such that the bobbin receiving groove 330 of the base 300, A current of about 25 [mA] is required for the mover 200 of the voice coil motor 600 according to the embodiment of the present invention to reach point A. [ On the other hand, in a general voice coil motor, a current amount of about 80 [mA] is required for the mover to reach the point A, and the power consumption of the voice coil motor according to an embodiment of the present invention is about 1 / 3.

That is, in an embodiment of the present invention, before the current is applied to the coil block 120 using the upper and lower elastic members 400 and 450, the mover 200 is already separated from the upper surface of the base 300 Therefore, the mover 200 can be raised to a required position with a smaller amount of current.

In order to drive the mover 200 of the voice coil motor 600 according to an embodiment of the present invention in a second direction SD close to the base 300, Current is applied.

A magnetic field generated by the reverse current applied to the coil block 120 and a magnetic field generated from the magnet 250 generate a downward force toward the base 300 in the mover 200, The mover 200 moves in the second direction SD toward the bottom surface 335 of the bobbin receiving groove 330 formed on the upper surface 320 of the base 300. [

In the embodiment of the present invention, even when moving the mover 200 in the second direction SD, the mover 200 can be moved with a current amount that is only about 1/3 of the amount of current required in the conventional voice coil motor .

5 is a block diagram showing a driving circuit for raising or lowering a mover of a voice coil motor according to an embodiment of the present invention.

1 and 5, when no current is applied to the coil block 120, the mover 200 is formed on the upper surface 320 of the base 300 by the upper and lower elastic members 400 and 450 And remains in a floating state from the bobbin receiving groove 330.

As the current is applied to the coil block 120 to drive the floating mover 200, the mover 200 moves in the first direction FD toward the top surface 320 of the base 300, And in a second direction SD opposite to the direction FD.

The voice coil motor 600 changes the flow of the current applied to the coil block 120 in order to drive the mover 200 in either the first direction FD or the second direction SD Includes a drive module (700).

The drive module 700 includes a control unit 710 and a current providing unit 790.

The control unit 710 is electrically connected to the external circuit board, and the control unit 710 generates the up control signal S1 and the down control signal S2.

The rising control signal S1 is a control signal for increasing the gap between the bobbin 210 of the voice coil motor 600 and the upper surface 320 of the base 300 and the falling control signal S2 is a control signal for increasing the gap between the voice coil motor 600 to reduce the gap between the bobbin 210 of the base 300 and the upper surface 320 of the base 300.

The current providing unit 790 increases the interval between the mover 200 and the upper surface 320 of the base 300 in the coil block 120 included in the stator 100 in response to the up control signal S1 Quot; forward current "for < / RTI >

On the other hand, the current providing unit 790 is responsive to the falling control signal S2 to supply the coil block 120 with the "reverse current" to reduce the distance between the mover 200 and the top surface 320 of the base 300, Lt; / RTI >

The current providing unit 790 includes a power source 715, a first unit circuit portion 720, and a second unit circuit portion 730.

The first unit circuit portion 720 includes, for example, first and second switch elements Q1 and Q2. In an embodiment of the present invention, the first and second switching elements Q1 and Q2 may each include a transistor including an input terminal, an output terminal and a gate.

The output terminal of the first switch element Q1 is electrically connected to the output terminal of the second switch element Q2.

The second unit circuit portion 730 includes third and fourth switch elements Q3 and Q4. In an embodiment of the present invention, the third and fourth switch elements Q1 and Q2 may each include a transistor including an input end, an output end and a gate. The output terminal of the third switch element Q3 is electrically connected to the output terminal of the fourth switch element Q4.

In an embodiment of the present invention, the first unit circuit portion 720 and the second unit circuit portion 730 are connected to the power source 715 in a parallel manner. That is, the input terminals of the first and second switch elements Q1 and Q2 of the first unit circuit portion 720 and the input terminals of the third and fourth switch elements Q3 and Q4 of the second unit circuit portion 730 The current supplied from the power source 715 is input.

The output terminals of the first and second switch elements Q1 and Q2 of the first unit circuit portion 720 and the output terminals of the third and fourth switch elements Q3 and Q4 of the second unit circuit portion 730 One end of the wire constituting the coil block 120 and the other end opposite to the one end are electrically connected to each other.

In operation, the rising control signal S1 output from the control unit 710 is applied to the gate of the first switch element Q1 and the gate of the fourth switch element Q4. The falling control signal S2 output from the control unit 710 is electrically connected to the gate of the second switch element Q2 and the gate of the third switch element Q3, respectively.

6, when the rising control signal S1 is outputted from the control unit 710, the rising control signal S1 is applied to the gates of the first switch element Q1 and the fourth switch element Q4, (S1) are applied together. Therefore, the first switch element Q1, the coil block 120, the fourth switch element Q4, and the power source 715 form a closed circuit, whereby a "forward current" is applied to the coil block 120.

The gap between the mover 200 of the voice coil motor 600 and the upper surface 320 of the base 300 is increased as a positive current is applied to the coil block 120. [ That is, the mover 200 is lifted from the upper surface 320 of the base 300.

On the other hand, when the falling control signal S2 is outputted from the control unit 710, as shown in Fig. 7, the respective gates of the second switch element Q2 and the third switch element Q3 are supplied with the falling control signal (S2) are applied together. Therefore, the third switch element Q3, the coil block 120, the second switch element Q2, and the power source 715 form a closed circuit, thereby causing the coil block 120 to generate a " Quot; reverse current "

The mover 200 of the voice coil motor 600 is moved to the inside of the bobbin receiving groove 330 formed on the upper surface 320 of the base 300 as the reverse current is applied to the coil block 120. That is, the mover 200 descends toward the bottom surface 335 of the bobbin receiving groove 330 formed on the upper surface 320 of the base 300.

In the embodiment of the present invention, although the configuration for controlling the direction of the current flowing through the coil block 120 using four switch elements Q1, Q2, Q3, and Q4 is shown and described, The direction of the current flowing through the coil block 120 can be changed using a wide variety of electric elements.

Although a configuration in which the directions of currents flowing through the coil block 120 are controlled differently by using the four switch elements Q1, Q2, Q3, and Q4 is shown and described in the embodiment of the present invention, A voltage may be applied to both ends of the coil block 120 and a voltage difference between both ends of the coil block 120 may be adjusted to raise or lower the bobbin 210. [

Hereinafter, a method of driving a voice coil motor according to an embodiment of the present invention will be described.

1 and 8, a reverse current FC (or an initial driving current), for example, is applied to the coil block 120 to drive the voice coil motor 600, Position.

The reference position may be the bottom surface 335 of the bobbin receiving groove 330 formed on the upper surface 320 of the base 300. In this case,

At this time, in order to bring the bobbin 210 into contact with the bottom surface 335 of the bobbin receiving groove 330 formed on the upper surface 320 of the base 300, the reverse current FC of the specific current amount D The bobbin 210 is dumped to the bottom surface 335 of the base 300 so that the base 300 and the bobbin 210 collide with each other and the waiting time until the bobbin 120 is stabilized Is required.

The moving speed of the bobbin 210 due to the reverse current FC (or the initial driving current) of the specific amount of current D applied to the coil block 120 decreases as it approaches the reference position, The coil block 120 is first supplied with the reverse current FC having a specific amount of current D as shown in the chain double-dashed line in FIG. 8 in order to reduce the waiting time required for the bobbin 210, The specific current amount D of the reverse current FC is gradually decreased for a predetermined time until the bobbin 210 contacts the bottom surface 335 to decrease the falling speed of the bobbin 120, Thereby reducing the waiting time of the mobile terminal 210.

The amount of current of the reverse current FC applied to the coil block 120 is reduced to separate the bobbin 210 from the reference position again and when the bobbin 210 reaches the initial position S, (SC) is applied to the gate of the transistor. The forward current SC can be increased continuously or stepwise.

Then, when the optimum focus required between the lens 205 fixed to the bobbin 210 and the image sensor module is formed, the amount of current of the forward current FC is kept constant so that the bobbin 210 is made to correspond to the optimum focus And stops at the position where it is.

The process of stopping the bobbin 210 at a position corresponding to the optimum focus may further include moving the bobbin 210 to a position slightly deviated from the optimal focus position and decreasing a current amount of the forward current to the coil block 120 The bobbin 210 is returned to the optimum focus position and the focus between the lens 205 and the image sensor module of the bobbin 210 can be finely adjusted by performing the microfocusing process.

Then, an optimum focus with the subject is formed between the image sensor module and the lens 205, and the image sensor module generates an image or a moving image of the subject with the best focus.

1 and 9, a forward current SC of a specific amount of current D is applied to the coil block 120 of the voice coil motor 600 to move the bobbin 210 to the reference position.

In one embodiment of the present invention, the reference position may be the inner surface of the top plate 510 of the cover can 500.

The amount of current of the forward current SC is reduced in the coil block 120 so that the bobbin 210 is separated from the top plate 510 of the cover can 500 as the reference position and the bobbin 210 is moved to the initial position S ), The reverse current (FC) is applied. The reverse current (FC) can be increased continuously or stepwise.

When the optimum focus required between the lens 205 fixed to the bobbin 210 and the image sensor module is formed, the current amount of the reverse current FC is kept constant, and the bobbin 210 is made to correspond to the optimum focus And stops at the position where it is.

The process of stopping the bobbin 210 at a position corresponding to the optimal focus includes moving the bobbin 210 to a position slightly deviated from the optimal focus position, The bobbin 210 is returned to the optimal focus position by slightly increasing the current amount and the focus between the lens 205 and the image sensor module of the bobbin 210 can be finely adjusted by performing the microfocusing process .

Then, between the image sensor module and the lens 205, an optimum focus is formed with the subject, and the image sensor module generates an image of the subject with the best focus.

The method of driving a voice coil motor according to an embodiment of the present invention is similar to that of the first embodiment except that the bobbin 210 shown in FIG. 1 is mounted on the upper surface 320 of the base 300 or the inner surface of the upper plate 510 of the cover can 500 And a current is applied to the coil block 120 until it reaches a position that makes an optimal focus with the image sensor module from the reference position to focus the focus of the mover 200 and the image sensor module The first current is applied to the coil block 120 to move the bobbin 210 to the reference position and the optimal position between the lens 205 and the image sensor module The bobbin 210 may be moved from the reference position based on the data by calculating data for maintaining the focus and applying a current amount of the current corresponding to the data to the coil block 120 .

The reference position may be an inner surface of the upper plate 510 of the cover can 500 or an upper surface 320 of the base 300. [ Lt; / RTI >

As described above in detail, the bobbin having the lens mounted thereon is floated from the bobbin receiving groove formed on the upper surface of the base on which the image sensor is mounted, and a mover including the bobbin is applied from the base by applying a forward current or a reverse current to the coil block. It is possible to drive the voice coil motor at a low current and to reduce the power consumption and to adjust the focus between the lens and the image sensor in a shorter time and to reduce the contact noise due to the driving of the bobbin It has an effect that can be reduced.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined by the following claims.

600 ... voice coil motor 100 ... stator
200 ... movable element 300 ... base
400 ... lower elastic member 450 ... upper elastic member
500 ... Cover cans

Claims (21)

A cover including a top plate and a side plate extending from the top plate;
A bobbin disposed in the cover;
A base disposed under the bobbin and coupled with the side plate of the cover;
A magnet disposed between the side plate of the cover and the bobbin;
A coil facing the magnet; And
And an elastic member coupled to the bobbin,
Wherein the elastic member includes an upper elastic member coupled to an upper portion of the bobbin and a lower elastic member coupled to a lower portion of the bobbin,
Wherein the upper elastic member and the lower elastic member each include an inner elastic portion coupled with the bobbin, an outer elastic portion disposed on the outer side of the inner elastic portion, and a connection elastic portion connecting the inner elastic portion and the outer elastic portion,
The inner elastic portion of the upper elastic member is disposed at a position lower than the outer elastic portion of the upper elastic member at an initial position where no current is applied to the coil, Is disposed at a position lower than the lower portion,
Wherein the bobbin is moved in a downward direction approaching the base when a reverse drive current is supplied to the coil at the initial position and is moved in an upward direction away from the base when a forward drive current is supplied to the coil, . The method according to claim 1,
In the initial position, the elastic member forms a first gap between the bobbin and the base, forms a second gap between the bobbin and the top plate of the cover,
Wherein the bobbin moves so as to decrease the first gap when the reverse driving current is supplied to the coil at the initial position and moves to decrease the second gap when the forward driving current is supplied to the coil, . The method according to claim 1,
Further comprising a housing disposed between the bobbin and the cover,
And the outer elastic portion of the upper elastic member is disposed on the upper surface of the housing and is coupled to the housing. The method of claim 3,
Wherein the housing includes a portion overlapping with the connection elastic portion of the upper elastic member in the optical axis direction and being recessed from the upper surface of the housing. The method of claim 3,
Wherein the housing includes an engaging boss formed on the upper surface of the housing,
And the outer elastic portion of the upper elastic member includes a hole coupled to the engagement boss. 6. The method of claim 5,
Wherein the engaging boss forms a gap between an upper surface of the housing and the upper plate of the cover. 5. The method of claim 4,
And at least a part of the connecting elastic portion of the upper elastic member is spaced apart from the upper plate and the housing of the cover. The method according to claim 1,
And the inner elastic portion of the lower elastic member is coupled to the lower surface of the bobbin by an adhesive or heat fusion. The method according to claim 1,
And the outer elastic portion of the lower elastic member is disposed on the upper surface of the base. The method according to claim 1,
When the forward driving current is applied to the coil at the initial position, as the bobbin moves upward, the inner elastic portion of the upper elastic member is positioned at a position lower than the outer elastic portion of the upper elastic member, And is moved to a position higher than the outer elastic portion. A voice coil motor according to claim 1;
A lens coupled to the bobbin of the voice coil motor; And
And an image sensor disposed under the lens. 12. The method of claim 11,
Wherein the bobbin is moved in one of the upward direction and the downward direction by adjusting a voltage difference between both ends of the coil. 13. The method of claim 12,
Wherein the voltage difference is generated and regulated by a PWM circuit. 15. A mobile phone comprising the camera of claim 13. Base; A bobbin disposed on the base and a coil wound on the bobbin; And an elastic member for supporting the bobbin, the method comprising:
Moving the bobbin to a reference position in a first direction by applying a first current to a coil wound on the bobbin in an initial position spaced from the base to the first gap and spaced from the cover to the second gap;
Reducing the first current applied to the coil at the reference position;
Applying a second current to the coil in a direction opposite to the first current to move the bobbin in a second direction opposite to the first direction;
Adjusting the second current applied to the coil or reapplying the first current to the coil to find the position of the best focus of the bobbin; and
And holding the bobbin at a position of the optimum focus. 16. The method of claim 15,
Wherein the voice coil motor further includes a cover coupled to the base and surrounding the bobbin,
Wherein the first current is a reverse current, the first direction is a direction in which the bobbin faces the base,
Wherein the second current is a forward current and the second direction is a direction in which the bobbin faces the cover. 17. The method according to claim 15 or 16,
Wherein adjusting the second current applied to the coil in the step of finding the position of the optimum focus of the bobbin decreases or increases the second current to find the position of the optimum focus. 17. The method according to claim 15 or 16,
Wherein the elastic member of the voice coil motor includes an upper elastic member coupled to an upper portion of the bobbin and a lower elastic member coupled to a lower portion of the bobbin,
Wherein the upper elastic member and the lower elastic member each include an inner elastic portion coupled with the bobbin, an outer elastic portion disposed on the outer side of the inner elastic portion, and a connection elastic portion connecting the inner elastic portion and the outer elastic portion,
The inner elastic portion of the upper elastic member is disposed at a position lower than the outer elastic portion of the upper elastic member at the initial position where no current is applied to the coil, Wherein the elastic member is disposed at a lower position than the elastic member. 17. The method according to claim 15 or 16,
And moving the bobbin to a reference position in a first direction moves the bobbin toward the base. 17. The method according to claim 15 or 16,
Wherein the step of reducing the first current applied to the coil at the reference position moves the bobbin in the second direction from the reference position. 17. The method of claim 16,
Wherein moving the bobbin further than a position of an optimum focus in a second direction opposite to the first direction moves the bobbin toward the cover.

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