KR20210087418A - Voice coil motor and driving method thereof - Google Patents

Abstract

A voice coil motor comprises: a stator including a coil block and a housing for fixing the coil block; a mover disposed inside the coil block and including a bobbin having a lens fixed thereto and a magnet disposed on the bobbin to face the coil block; a base onto which the housing is fixed, wherein an opening is formed at a position of the base corresponding to the lens and a bobbin accommodating groove for accommodating a lower surface of the bobbin is formed on an upper surface of the base 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 accommodating groove regardless of a posture of the mover when a driving signal is not applied to the coil block.

Description

Voice coil motor and driving method thereof

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.

Recently, a mobile phone having a built-in ultra-small digital camera has been developed.

In the case of a miniature digital camera applied to a conventional mobile phone, etc., the distance between the image sensor and the lens that changes external light into a digital image or digital image could not be adjusted, but recently, a voice coil motor that adjusts the distance between the image sensor and the lens and With the development of the same lens driving device, it is possible to obtain an improved digital image or digital image from a miniature digital camera.

In general, the voice coil motor has a lens mounted 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 side of the base.

In addition, a leaf spring is coupled to the bobbin of the voice coil motor so that the bobbin is always in contact with the base by the elastic force of the leaf spring when the voice coil motor is not operated. That is, the bobbin of the conventional voice coil motor is driven in one direction toward the top with respect to the base.

Since the conventional voice coil motor is driven in only one direction, a driving force greater than the weight of the bobbin and the elastic force of the leaf spring is required to drive the voice coil motor, and thus power consumption of the voice coil motor is greatly increased.

In addition, since a driving force greater than the bobbin's own weight and the elastic force of the leaf spring is required to drive the voice coil motor, the size of the coil wound on the magnet or bobbin is increased, thereby increasing the overall size of the voice coil motor.

In addition, when the shape of the leaf spring is deformed, the focus between the lens and the image sensor is not accurately achieved, so that image quality is greatly reduced.

(Patent Document 1) KR10-2007-0062440 A

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

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be.

In one embodiment, the voice coil motor includes a stator including a coil block and a housing for fixing the coil block; a mover disposed inside the coil block and including a bobbin having a lens fixed therein and a magnet disposed on the bobbin to face the coil block; a base on which the housing is fixed, an opening is formed at a position corresponding to the lens, and a bobbin receiving groove for accommodating a lower surface of the bobbin is formed on an upper surface facing the bobbin; and a lower elastic fixed 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 receiving groove when no driving signal is applied to the coil block, regardless of the posture of the mover include absence.

In one embodiment, the voice coil motor includes a stator including a coil block and a housing for fixing the coil block; a mover disposed inside the coil block and including a bobbin having a lens fixed therein and a magnet disposed on the bobbin to face the coil block; a base on which the housing is fixed, an opening is formed at a position corresponding to the lens, and a bobbin receiving groove for accommodating a lower surface of the bobbin is formed on an upper surface facing the bobbin; and a lower elastic member fixed to the bobbin and the base to form a gap between a lower surface of the bobbin and a bottom surface formed by the bobbin receiving groove, wherein the bobbin supported by the lower elastic member is the coil block and a first direction away from the base by the first force generated by the magnet and a second direction 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 thereon, a mover disposed on the base and disposed above the bobbin receiving groove and including a magnet, fixed to the base and facing the magnet In the voice coil motor comprising a stator including a coil block and an elastic member for floating the mover on an upper portion of the bobbin receiving groove, an initial driving signal is applied to the coil block to move the bobbin to a reference position to move the bobbin sorting; moving the bobbin from the reference position to a focus position by applying a driving current of increasing or decreasing level to the coil block; and maintaining the level of the driving current constant when an optimal focus is formed between the lens and the image sensor module to stop the bobbin at a position corresponding to the optimal focus.

In one embodiment, a method of driving a voice coil motor includes a base having a bobbin receiving groove formed thereon, a mover disposed on the base and disposed above the bobbin receiving groove and including a magnet, fixed to the base and facing the magnet aligning the bobbin by moving the bobbin to a reference position by applying a reference current to the coil block, including a stator including a coil block and an elastic member for floating the mover on the bobbin receiving groove; moving the bobbin from the reference position to a focus position by applying a driving current of increasing or decreasing level to the coil block; and maintaining the level of the driving current constant when an optimal focus is formed between the lens and the image sensor module to stop the bobbin at a position corresponding to the optimal focus.

According to the voice coil motor and its driving method according to the present invention, a bobbin with a lens is floated from a bobbin receiving groove formed on an upper surface of a base on which an image sensor is mounted, and a forward current or a reverse current is applied to the coil block to generate the bobbin By bidirectionally driving the movable element including the mover in the direction away from the base or in the direction approaching the base, the voice coil motor can be driven with a low current and power consumption can be reduced, and the focus between the lens and the image sensor can be adjusted within a shorter time. It has the effect of reducing the contact noise according to the driving.

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

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings. In this process, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, terms specifically defined in consideration of the configuration and operation of the present invention may vary depending on the intention or custom of the user or operator. Definitions of these terms should be interpreted as meanings and concepts consistent with the technical idea of the present invention based on the contents throughout this specification.

1 is an exploded perspective view of a voice coil motor according to an embodiment of the present invention. FIG. 2 is an assembly cross-sectional view of FIG. 1 .

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 to be described later.

The coil block 120 is formed, for example, by winding a long wire insulated by an insulating resin into a tubular shape. When a voltage having a voltage difference is applied to the coil block 120 formed by winding a long wire insulated by an insulating resin, a magnetic field is generated from the coil block 120, and the direction of the magnetic field flows through the coil block 120. It changes 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 posts 154 .

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

A plurality of coupling bosses 156 are formed on the upper surface of the housing body 152 for fixing an upper elastic member to be described later.

The pillars 154 protrude 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 peripheral surface of the pillars (154). The pillars 154 may be coupled to the upper surface of the base 300 to be described later.

In one embodiment of the present invention, the coil block 120 is attached to the pillars 154 of the housing 150 by an adhesive or the like in a state in which the coil block 120 is wound in a cylindrical shape or directly wound on the pillars 154 of the housing 150 . can be

As shown in FIG. 1 , the housing 150 includes a groove 155 that overlaps with the connection upper elastic part 453 of the upper elastic member 450 in the direction of the optical axis and is recessed from the upper surface of the housing 150 . can At an initial position where no current is applied to the coil block 120 , a first gap is formed between the connecting elastic portion 453 of the upper elastic member 450 and the bottom surface of the groove 155 of the housing 150 , When the reverse driving current is supplied to the coil block 120 at the position, the connection elastic part 153 of the upper elastic member 150 may move to reduce the first gap.

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

Flat magnet fixing parts 215 for fixing the plurality of magnets 250 are formed on the outer peripheral surface of the bobbin 210 . For example, four magnet fixing parts 215 are formed at equal intervals on the outer peripheral surface of the bobbin 210 , for example.

The magnets 250 are, for example, formed in a plate shape, and the magnets 250 are fixed to each of the magnet fixing parts 215 formed on the outer peripheral surface of the bobbin 210 . Each of the magnets 250 may be attached to the magnet fixing part 215 by an adhesive or the like.

Each magnet 250 is disposed to face the coil block 120 of the stator 100 .

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

The base 300 is, for example, formed 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 built in the bobbin 210 of the mover 200 passes is formed in the central portion of the base 300 .

The four corners of the upper surface 320 of the base 300 formed in the shape of a plate are each formed with coupling posts 325 , and the coupling posts 325 are mutually coupled to the cover can 500 and the base 300 to be described later. plays a role

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

Meanwhile, a bobbin receiving groove 330 concavely formed from the upper surface 320 is formed on the upper surface 320 of the base 300 . The bobbin receiving groove 330 serves to receive the lower end of the bobbin 210 .

The bobbin receiving groove 330 is formed to be larger than the planar area of the bobbin 210 , and the bobbin 210 and the base 300 may partially overlap each other by the bobbin receiving groove 330 .

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 other hand, the shock absorbing member 350 formed along the opening 310 of the base 300 is disposed on the bottom surface 335 of the base 300 formed by the bobbin receiving groove 330 . The shock absorbing member 350 absorbs, for example, a shock caused by a collision between the bobbin 210 and the bottom surface 335 of the base 300 .

In an 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. can

The lower elastic member 400 elastically supports the bobbin 210 of the mover 200 , and the lower elastic member 400 has the lower surface of the bobbin 210 of the mover 200 receiving the bobbin of the base 300 . It is made to float on the upper part of the groove (330).

That is, the lower elastic member 400 is formed on 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 surfaces 335 formed by the receiving grooves 330 .

Here, the posture of the bobbin 210 means that the lens of the bobbin 210 faces downward, the lens of the bobbin 210 faces upward, or the lens of the bobbin 210 is disposed parallel to the ground.

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

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

Since the inner lower elastic part 410 is coupled to the lower surface of the bobbin 210 , the inner lower elastic part 410 is also formed in a size to be inserted into the bobbin receiving groove 330 of the base 300 .

The outer lower elastic part 420 is disposed outside the inner lower elastic part 410 , and the outer lower elastic part 420 is formed in a rectangular frame shape.

The outer lower elastic part 420 is formed in a size larger than the bobbin receiving groove 330 of the base 300 , and thus the outer lower elastic part 420 is disposed on the upper surface 320 of the base 300 . The outer lower elastic part 420 may be fixed on the upper surface 320 of the base 300 by, for example, pillars 154 of the housing 150 of the stator 100 .

The connection lower elastic part 430 elastically connects the inner lower elastic part 410 and the outer lower elastic part 420 to each other, and the inner lower elastic part 410 has elasticity by the connection lower elastic part 430 . do.

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

The inner lower elastic part 410 is spaced apart from the bottom surface 335 formed by the bobbin receiving groove 330, and when a driving signal is not applied to the coil block 120, the inner lower elastic part 410, the outer The lower elastic part 420 and the connecting lower elastic part 430 may be disposed on the same plane. Alternatively, when a driving signal is not applied to the coil block 120 , the inner lower elastic part 410 may be disposed at a slightly lower position than the outer lower elastic part 420 .

In one embodiment of the present invention, 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 Accordingly, the mover 200 may be driven in a direction away from the base 300 or the mover 200 may be driven in a direction closer to the base 300 .

That is, when the mover 200 is spaced apart from the upper surface 320 of the lower base 300 , the mover 200 faces the base 300 by changing the direction of the current applied to the coil block 120 . It may be driven in a downward direction or an upward direction away from the base 300 , respectively.

Meanwhile, 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 part 451 , an outer upper elastic part 452 , and a connection upper elastic part 453 .

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

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

Referring back 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 from the edge of the upper plate 510 toward the base 300 . Including, the side plate 520 is coupled to the side of the base (300).

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

In one embodiment of the present invention, 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 the coil block 120 . ) is driven in the second direction SD when a reverse current opposite to the forward current is applied.

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

FIG. 3 is a cross-sectional view conceptually illustrating the voice coil motor shown in FIG. 1 . FIG. 4 is a graph illustrating a relationship between a driving current amount and a movement amount for driving the voice coil motor shown in FIG. 1 .

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, the lower and When no current is applied to the coil block 120 by the elastic force of the upper elastic members 400 and 450 , the mover 200 is spaced apart from the bottom surface 335 of the bobbin receiving groove 330 of the base 300 . is floated on

That is, in one embodiment of the present invention, since the bobbin 210 elastically fixed to the lower and upper elastic members 400 and 450 is floated by the bobbin receiving groove 330 , the bobbin 210 is the coil block 120 . ) can be driven in either direction in the second direction SD toward the upper surface 320 of the base 300 or in the first direction FD away from the upper surface 320 of the base 300 according to the direction of the current applied to the can be

A forward current is applied to the coil block 120 in order to widen the distance between the image sensor disposed under the base 300 and the lens included in the mover 200 , and thereby the first magnetic field from the coil block 120 . This happens.

The first magnetic field generated from the coil block 120 acts with 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 part of the base 300 . Generates a lifting force that rises in the first direction FD toward the. The lifting force is increased in proportion to the strength 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 move the mover 200 toward the base 300 when no current is applied to the coil block 120 . Since it is not pressurized, the moment when a forward current is applied to the coil block 120 , the mover 200 starts to rise in the first direction FD away from the upper surface of the base 300 .

Hereinafter, in the graph of FIG. 4 , the current in the region where the X-axis becomes positive is defined as a “forward current”, and the current in the region in which the X-axis becomes negative in the graph of FIG. 4 is defined as a “reverse current”.

In addition, the mover 200 of the voice coil motor 600 according to an embodiment of the present invention is the base by the bobbin receiving groove 330 of the base 300 before the forward current is applied to the coil block 120 . Since it is already separated from 300, an amount of current of about 25 [mA] is required for the mover 200 of the voice coil motor 600 according to an embodiment of the present invention to reach point A. On the other hand, in a typical voice coil motor, an amount of current 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 1/1/2 of that of the conventional voice coil motor. only about 3

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

On the other hand, in order to drive the mover 200 of the voice coil motor 600 according to an embodiment of the present invention in the second direction SD closer to the base 300, the coil block 120 receives a reverse current instead of a forward current. Apply current.

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

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

5 is a block diagram illustrating 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. It maintains a floating state from the bobbin receiving groove 330 .

Meanwhile, as current is applied to the coil block 120 to drive the floating mover 200 , the mover 200 moves in the first direction FD or the first direction toward the upper surface 320 of the base 300 . It is driven in the second direction SD that is opposite to the direction FD.

In order to drive the mover 200 in either the first direction FD or the second direction SD, the voice coil motor 600 changes the flow of current applied to the coil block 120 . The main includes a driving module 700 .

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

The control unit 710 is electrically connected to an external circuit board, and the control unit 710 generates a rising control signal S1 and a falling 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 the voice coil motor ( This is a control signal for reducing the gap between the bobbin 210 of the 600 and the upper surface 320 of the base 300 .

The current providing unit 790 increases the distance 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 rising control signal S1. It provides a "forward current" for

On the other hand, the current providing unit 790 is a “reverse current” for reducing the gap between the mover 200 and the upper surface 320 of the base 300 in the coil block 120 in response to the descending control signal S2. provides

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

The first unit circuit unit 720 includes, for example, first and second switch elements Q1 and Q2 . In an embodiment of the present invention, each of the first and second switch elements Q1 and Q2 may 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 unit 730 includes third and fourth switch elements Q3 and Q4. In an embodiment of the present invention, each of the third and fourth switch elements Q1 and Q2 may include a transistor including an input terminal, an output terminal 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 unit 720 and the second unit circuit unit 730 are connected in a parallel manner with respect to the power source 715 . That is, the input terminals of the first and second switch elements Q1 and Q2 of the first unit circuit unit 720 and the input terminals of the third and fourth switch elements Q3 and Q4 of the second unit circuit unit 730 . Each of the currents supplied from the power source 715 is input.

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

In terms of 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.

Accordingly, when the rising control signal S1 is output from the control unit 710 , as shown in FIG. 6 , the rising control signal is applied to the gates of the first switch element Q1 and the fourth switch element Q4 . (S1) is applied together. Accordingly, 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 .

As the forward current is applied to the coil block 120 , the distance between the mover 200 of the voice coil motor 600 and the upper surface 320 of the base 300 is increased. That is, the mover 200 is raised from the upper surface 320 of the base 300 .

Meanwhile, when the falling control signal S2 is output from the control unit 710 , as shown in FIG. 7 , the falling control signal is applied to the gates of the second switch element Q2 and the third switch element Q3 . (S2) is applied together. Accordingly, the third switch element Q3, the coil block 120, the second switch element Q2, and the power supply 715 form a closed circuit, and thereby the coil block 120 has a "forward current" flowing in the opposite direction. "reverse current" is applied.

As the reverse current is applied to the coil block 120 , the mover 200 of the voice coil motor 600 moves into the bobbin receiving groove 330 formed in the upper surface 320 of the base 300 . That is, the mover 200 descends toward the bottom surface 335 of the bobbin receiving groove 330 formed in the upper surface 320 of the base 300 .

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

Although in one embodiment of the present invention, the configuration for controlling the direction of the current flowing in the coil block 120 differently using the four switch elements Q1, Q2, Q3, Q4 is shown and described, but differently, The bobbin 210 may be raised or lowered by applying voltages to both ends of the coil block 120 , respectively, and adjusting the voltage difference between both ends of the coil block 120 .

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

1 and 8 , for example, a reverse current FC (or an initial driving current) is applied to the coil block 120 to drive the voice coil motor 600 to drive the bobbin 210 as a reference. move to position

In an embodiment of the present invention, the reference position may be the bottom surface 335 of the bobbin receiving groove 330 formed in the upper surface 320 of the base 300 .

At this time, in order to contact the bobbin 210 to the bottom surface 335 of the bobbin receiving groove 330 formed in the upper surface 320 of the base 300, the coil block 120 has a specific current amount D in the reverse direction current (FC). ), the bobbin 210 descends to the bottom surface 335 of the base 300 so that the base 300 and the bobbin 210 collide, thereby increasing the waiting time until the bobbin 210 is stabilized. is required

In one embodiment of the present invention, the moving speed of the bobbin 210 by the reverse current FC (or initial driving current) of a specific current amount D applied to the coil block 120 is reduced as it approaches the reference position. In order to reduce the waiting time required for the bobbin 210 in contact with the position to be stabilized, the reverse current FC having a specific current amount D in the coil block 120 first as shown in the graph shown by the dashed-dotted line in FIG. 8 . ) is applied, and for a predetermined time until the bobbin 210 comes into contact with the bottom surface 335, the specific current amount D of the reverse current FC is gradually decreased to decrease the descending speed of the bobbin 210 to reduce the bobbin Reduce the waiting time of 210. After the bobbin 210 is disposed at the reference position, a time elapses until the bobbin 210 is stabilized, and the bobbin 210 may move upwardly away from the base 300 from the reference position.

Then, the amount 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, the coil block 120 . A forward current (SC) is applied to The forward current SC can be increased continuously or in a stepwise fashion.

Then, when the optimal 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 maintained constant so that the bobbin 210 corresponds to the optimal focus. stop at the position

The process of stopping the bobbin 210 at a position corresponding to the optimal focus is a process of additionally moving the bobbin 210 to a position slightly deviated from the optimal focus position and reducing the amount of forward current in the coil block 120 . By doing this, the bobbin 210 is returned to the optimal focus position, and the focus between the lens 205 of the bobbin 210 and the image sensor module can be more finely adjusted by performing such a fine focus process.

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

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

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

Then, the current amount of the forward current SC is reduced in the coil block 120 to separate the bobbin 210 from the upper plate 510 of the cover can 500 which is the reference position, and the bobbin 210 moves to the initial position S ), the reverse current (FC) is applied. The reverse current FC can be increased continuously or in a stepwise fashion.

Then, when the optimal 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 maintained constant so that the bobbin 210 corresponds to the optimal focus. stop at the position

The process of stopping the bobbin 210 at the position corresponding to the optimal focus is the process of moving the bobbin 210 to a position slightly deviated from the position of the optimal focus, and the direction of the reverse current SC to the coil block 120 . By slightly increasing the amount of current, the bobbin 210 is returned to the optimal focus position, and the focus between the lens 205 of the bobbin 210 and the image sensor module can be more finely adjusted by performing the fine focus process. .

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

In the method of driving the voice coil motor according to an embodiment of the present invention, any one of the inner surface of the upper surface 320 of the base 300 or the upper plate 510 of the cover can 500 by using the bobbin 210 shown in FIG. 1 . A reference position is set by contacting one, and a current is applied to the coil block 120 from the reference position to a position forming an optimal focus with the image sensor module to focus between the mover 200 and the image sensor module. Although the method of adjusting has been illustrated and described, differently from this, the first current is applied to the coil block 120 to move the bobbin 210 to the reference position, and the optimal distance between the lens 205 and the image sensor module based on the subject. Data for maintaining focus may be calculated, and an amount of current corresponding to the data may be applied to the coil block 120 to move the bobbin 210 from the reference position based on the data.

At this time, the amount of current applied to the coil block 120 has an intensity corresponding to the data, and the reference position is the inner surface of the upper plate 510 of the cover can 500 or the upper surface 320 of the base 300 . can be

As described in detail above, the bobbin with the lens is floated from the bobbin receiving groove formed on the upper surface of the base on which the image sensor is mounted, and the mover including the bobbin is moved from the base by applying a forward current or a reverse current to the coil block. By bidirectional driving in the direction away from or approaching the base, the voice coil motor can be driven with low current and power consumption can be reduced, the focus between the lens and the image sensor can be adjusted within a shorter time, and the contact noise caused by the operation of the bobbin can be reduced. have the effect of reducing it.

Although the embodiments according to the present invention have been described above, these are merely exemplary, and those of ordinary skill in the art will understand that various modifications and equivalent ranges of embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be defined by the following claims.

600...voice coil motor 100...stator
200...Movers 300...Base
400...lower elastic member 450...upper elastic member
500...cover cans

Claims (20)

a cover including an upper plate and a side plate extending from the upper plate;
a bobbin disposed within the cover;
a base disposed under the bobbin and coupled to the side plate of the cover;
a housing disposed between the cover and the bobbin;
a magnet and a coil disposed in the cover and configured to move the bobbin in an optical axis direction; and
an upper elastic member coupled to the bobbin and the housing;
The upper elastic member includes an inner elastic part coupled to the bobbin, an outer elastic part disposed on the upper surface of the housing, and a connection elastic part connecting the inner elastic part and the outer elastic part,
The housing includes a groove recessed from the upper surface of the housing, and a coupling boss protruding from the upper surface of the housing,
The groove of the housing overlaps the connection elastic part of the upper elastic member in the optical axis direction,
The coupling boss of the housing passes through the upper elastic member to form a gap between the upper surface of the housing and the upper plate of the cover. According to claim 1,
In an initial position where no current is applied to the coil, the upper elastic member supports the bobbin to form a first gap between the bobbin and the base. 3. The method of claim 2,
When a reverse driving current is supplied to the coil, the bobbin moves from the initial position to the first gap in a downward direction approaching the base along an optical axis to decrease, and is disposed at a reference position. 4. The method of claim 3,
After the bobbin is disposed at the reference position, a time elapses until the bobbin is stabilized, and the voice coil motor moves upward away from the base from the reference position. 3. The method of claim 2,
A second gap is formed between the connection elastic part of the upper elastic member and the bottom surface of the groove of the housing in the initial position. 3. The method of claim 2,
and a lower elastic member coupled to the bobbin and the base,
The lower elastic member includes an inner elastic part coupled to the bobbin, an outer elastic part coupled to the base, and a connecting elastic part connecting the inner elastic part and the outer elastic part,
The upper surface of the base includes a first region overlapping the connection elastic part of the lower elastic member in the optical axis direction,
A third gap is formed between the connecting elastic portion of the lower elastic member and the first region of the base in the initial position,
When a reverse driving current is supplied to the coil at the initial position, the third gap is reduced by movement of the connection elastic part of the lower elastic member. 3. The method of claim 2,
The upper elastic member supports the bobbin to form a fourth gap between the bobbin and the upper plate of the cover in the initial position,
When a forward driving current is supplied to the coil, the bobbin moves from the initial position along an optical axis in an upward direction away from the base to decrease the fourth gap. According to claim 1,
The magnet is disposed between the side plate of the cover and the bobbin,
The coil is a voice coil motor facing the magnet. According to claim 1,
The magnet is disposed on the bobbin,
The coil is a voice coil motor disposed in the housing. 3. The method of claim 2,
In the initial position, the inner elastic part of the upper elastic member is disposed at a lower position than the outer elastic part of the upper elastic member. 6. The method of claim 5,
When a reverse driving current is supplied to the coil at the initial position, the second gap is reduced by movement of the connection elastic part of the upper elastic member. 3. The method of claim 2,
In the initial position, at least a portion of the connection elastic part of the upper elastic member is spaced apart from the upper plate of the cover and the housing. 7. The method of claim 6,
The inner elastic portion of the lower elastic member is a voice coil motor coupled to the lower surface of the bobbin by adhesive or thermal fusion. 11. The method of claim 10,
When a 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 lower than the outer elastic portion of the upper elastic member. A voice coil motor that is moved to a higher position than the outer elastic part. a cover including an upper plate and a side plate extending from the upper plate;
a bobbin disposed within the cover;
a base disposed under the bobbin and coupled to the side plate of the cover;
a housing disposed between the cover and the bobbin;
a magnet and a coil disposed in the cover and configured to move the bobbin in an optical axis direction; and
an upper elastic member coupled to the bobbin and the housing;
The upper elastic member includes an inner elastic part coupled to the bobbin, an outer elastic part disposed on the upper surface of the housing, and a connection elastic part connecting the inner elastic part and the outer elastic part,
The housing includes a groove recessed from the upper surface of the housing, and a coupling boss protruding from the upper surface of the housing,
A gap is formed between the connection elastic part of the upper elastic member and the bottom surface of the groove of the housing in the optical axis direction at an initial position where no current is applied to the coil;
In the initial position, the coupling boss of the housing passes through the upper elastic member in the optical axis direction to form a gap between the bobbin and the upper plate of the cover. 16. The method of claim 15,
In the initial position, the inner elastic part of the upper elastic member is disposed at a lower position than the outer elastic part of the upper elastic member. 16. The method of claim 15,
When a reverse driving current is supplied to the coil, the bobbin moves from the initial position to the base in the optical axis direction and is disposed at a reference position,
After the bobbin is disposed at the reference position, a time elapses until the bobbin is stabilized, and the voice coil motor moves upward away from the base from the reference position. The voice coil motor of any one of claims 1 to 17;
a lens coupled to the bobbin of the voice coil motor; and
and an image sensor disposed at a position corresponding to the lens. A mobile phone comprising the camera of claim 18 . a cover including an upper plate and a side plate extending from the upper plate;
a bobbin disposed within the cover;
a base disposed under the bobbin and coupled to 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
A voice coil motor including an elastic member coupled to the bobbin.

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