KR102164288B1 - Voice coil motor and driving method thereof - Google Patents

Abstract

The voice coil motor includes: a stator including a coil block and a housing fixing the coil block; A mover including a bobbin disposed inside the coil block and having a lens fixed therein, and a magnet disposed on the bobbin to face the coil block; A base in which the housing is fixed, an opening is formed at a position corresponding to the lens, and a bobbin receiving groove is formed on an upper surface facing the bobbin to receive a lower surface of the bobbin; And a lower elasticity fixed to the bobbin and the base such that a gap is formed between the bottom surface of the bobbin and the bottom surface formed by the bobbin receiving groove regardless of the posture of the mover when a driving signal is not applied to the coil block. Including absence.

Description

Voice coil motor and driving method thereof {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 with a built-in micro-digital camera has been developed.

In the case of conventional ultra-small digital cameras applied to mobile phones, the distance between the image sensor and the lens that converts 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 The same lens driving device has been developed so that it is possible to obtain an improved digital image or digital image from a micro digital camera.

In general, a 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 at the rear of the base.

In addition, a leaf spring is coupled to the bobbin of the voice coil motor so that when the voice coil motor is not operated, the bobbin is always in 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 top with respect to the base.

Since the conventional voice coil motor is driven only in one direction, 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, and thus the power consumption of the voice coil motor is greatly increased.

In addition, 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, so the size of the coil wound around the magnet or the bobbin increases, thereby increasing the overall size of the voice coil motor.

In addition, when the shape of the leaf spring is deformed, there is a problem in that the focus between the lens and the image sensor is not accurately achieved, and the 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 problem to be achieved by the present invention is not limited to the technical problems mentioned above, and other technical problems that are not mentioned can be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. 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 including a bobbin disposed inside the coil block and having a lens fixed therein, and a magnet disposed on the bobbin to face the coil block; A base in which the housing is fixed, an opening is formed at a position corresponding to the lens, and a bobbin receiving groove is formed on an upper surface facing the bobbin to receive a lower surface of the bobbin; And a lower elasticity fixed to the bobbin and the base such that a gap is formed between the bottom surface of the bobbin and the bottom surface formed by the bobbin receiving groove regardless of the posture of the mover when a driving signal is not applied to the coil block. Including 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 including a bobbin disposed inside the coil block and having a lens fixed therein, and a magnet disposed on the bobbin to face the coil block; A base in which the housing is fixed, an opening is formed at a position corresponding to the lens, and a bobbin receiving groove is formed on an upper surface facing the bobbin to receive a lower surface of 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, wherein the bobbin supported by the lower elastic member is the coil block And a first direction away from the base by a first force generated by the magnet and a second direction closer to the base by the bobbin receiving groove.

As an 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. A voice coil motor comprising a stator including a coil block and an elastic member for floating the mover over the bobbin receiving groove, wherein the bobbin is moved to a reference position by applying an initial driving signal to the coil block. Aligning; Applying a driving current whose level is increased or decreased to the coil block to move the bobbin from the reference position to a focus position; And stopping the bobbin at a position corresponding to the optimum focus by maintaining the level of the driving current constant when an optimum focus is formed between the lens and the image sensor module.

As an 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. A stator including a coil block and an elastic member for floating the mover above the bobbin receiving groove, and applying a reference current to the coil block to move the bobbin to a reference position to align the bobbin; Applying a driving current whose level is increased or decreased to the coil block to move the bobbin from the reference position to a focus position; And stopping the bobbin at a position corresponding to the optimum focus by maintaining 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 its driving method according to the present invention, the bobbin in 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 forward current or a reverse current is applied to the coil block. By driving the included mover in both directions 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 faster time. It has an effect of reducing contact noise due to driving.

1 is an exploded perspective view of a voice coil motor according to an embodiment of the present invention.
2 is an assembly cross-sectional view of FIG. 1.
3 is a cross-sectional view conceptually showing the voice coil motor shown in FIG. 1.
4 is a graph showing the relationship between the amount of driving current and the amount of movement for driving the voice coil motor shown in FIG. 3.
5 is a block diagram showing a driving circuit for raising or lowering the 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 a 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, embodiments of 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 description. In addition, terms specifically defined in consideration of the configuration and operation of the present invention may vary according to the intention or custom of users or operators. 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 the present specification.

1 is an exploded perspective view of a voice coil motor according to an embodiment of the present invention. 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 by winding a long electric wire insulated by an insulating resin in a cylindrical 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 pillars 154.

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

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

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 adhesive or the like in the state of being 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 the connection upper elastic portion 453 of the upper elastic member 450 in the direction of the optical axis and is depressed from the upper surface of the housing 150. I can. A first gap is formed between the connection elastic portion 453 of the upper elastic member 450 and the bottom surface of the groove 155 of the housing 150 at an initial position where no current is applied to the coil block 120, and When the reverse driving current is supplied to the coil block 120 at the position, the connection elastic portion 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 and adjusts 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 in, for example, a hollow cylindrical shape, and a thread for fixing the lens 205 is formed on the inner circumferential surface of the bobbin 210.

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

The magnets 250 are formed in, for example, a plate shape, and the magnets 250 are fixed to the respective magnet fixing portions 215 formed on the outer circumferential 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 of the magnets 250 is disposed to face the coil block 120 of the stator 100.

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

The base 300 is formed in, for example, a rectangular parallelepiped plate shape, 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.

Each of the four corners of the upper surface 320 of the base 300 formed in a plate shape are formed with coupling pillars 325, the coupling pillars 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 light passing through the lens 205 of the bobbin 210 are fixed on the rear surface of the base 300.

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

The bobbin receiving groove 330 is formed 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.

Meanwhile, a 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 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 is formed in an annular plate shape having a thin thickness. I can.

The lower elastic member 400 elastically supports the bobbin 210 of the mover 200, and the lower elastic member 400 has a bottom surface of the bobbin 210 of the mover 200 accommodates the bobbin of the base 300 Float on the top of the groove 330.

That is, the lower elastic member 400 is a bobbin 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 current is not 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 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 portion 410 is formed in, for example, an annular ring shape, and the inner lower elastic portion 410 is coupled to the lower surface of the bobbin 210. The inner lower elastic portion 410 is coupled to the lower surface of the bobbin 210 by, for example, an adhesive or heat 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 portion 420 is disposed outside the inner lower elastic portion 410, and the outer lower elastic portion 420 is formed in a rectangular frame shape.

The outer lower elastic part 420 is formed to have 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 above 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 when a driving signal is not applied to the coil block 120, the inner lower elastic portion 410, the outer side The lower elastic part 420 and the connection lower elastic part 430 may be disposed on the same plane. In contrast, when a driving signal is not applied to the coil block 120, the inner lower elastic portion 410 may be disposed at a slightly lower position than the outer lower elastic portion 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 total 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 in a direction closer to the base 300, respectively.

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

On the other hand, 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.

The outer upper elastic portion 452 disposed on the upper surface of the housing body 152 is formed with a coupling hole 455 that is coupled to the coupling boss 156 formed 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 an edge of the upper plate 510 in a direction toward the base 300. Includes, and the side plate 520 is coupled to the side surface of the base 300.

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

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.

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

3 is a cross-sectional view conceptually showing the voice coil motor shown in FIG. 1. 4 is a graph showing a relationship between a driving current amount and a moving 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 current is not applied to the coil block 120 by the elastic force of the upper elastic members 400, 450, the mover 200 is a position spaced apart from the bottom surface 335 of the bobbin receiving groove 330 of the base 300 Is plotted 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 a coil block 120 It is possible to drive in both directions 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 ). Can be.

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

The first magnetic field generated from the coil block 120 interacts 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. It generates a lifting force that rises in the first direction FD toward. The lifting force increases 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 the pressure is not applied, the mover 200 starts 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 a positive number is defined as “forward current”, and in the graph of FIG.

In addition, before the forward current is applied to the coil block 120, the mover 200 of the voice coil motor 600 according to an exemplary embodiment of the present invention can be used as the base by the bobbin receiving groove 330 of the base 300. Since it is already separated from 300, a current amount 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 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/ It's only about 3.

That is, in one 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 spaced apart from the upper surface of the base 300. Therefore, even with a smaller amount of current, the mover 200 can be raised to a required position.

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 has a reverse direction instead of a forward current. Apply current.

A downward force toward the base 300 is generated in the mover 200 by the magnetic field generated by the reverse current applied to the coil block 120 and the magnetic field generated from the magnet 250, and by the downward force 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 one embodiment of the present invention, even when moving the mover 200 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 by 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. It maintains a floating state from the bobbin receiving groove 330.

On the other hand, as current is applied to the coil block 120 to drive the floating mover 200, the mover 200 is in a first direction (FD) or a first direction toward the upper surface 320 of the base 300. It is driven in a 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 ( It is a control signal for reducing the gap between the bobbin 210 of 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. For "forward current".

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 to the coil block 120 in response to the down 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 part 720 includes, for example, first and second switch elements Q1 and Q2. In an embodiment of the present invention, the first and second switch 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 unit 730 includes third and fourth switch elements Q3 and Q4. In one embodiment of the present invention, the third and fourth switch elements Q1 and Q2 may each 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 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 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 them is input with a current provided from the power source 715.

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 wire constituting the coil block 120 and the other end facing 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 down 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.

Therefore, 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 and fourth switch elements Q1 and Q4. (S1) is applied together. Accordingly, the first switch element Q1, the coil block 120, the fourth switch element Q4, and the power supply 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 increases. That is, the mover 200 is raised from the upper surface 320 of the base 300.

On the other hand, when the down control signal S2 is output from the control unit 710, as shown in FIG. 7, the down control signal is applied to the gates of the second switch device Q2 and the third switch device 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, whereby the coil block 120 flows in the opposite direction to the “forward current”. 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 on 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 on the upper surface 320 of the base 300.

In one embodiment of the present invention, although a configuration for differently controlling the directions of the current flowing through the coil block 120 using four switch elements Q1, Q2, Q3, 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 devices.

Although in one embodiment of the present invention, a configuration in which the directions of current flowing through the coil block 120 are differently controlled using four switch elements Q1, Q2, Q3, and Q4 are shown and described. The bobbin 210 may be raised or lowered by applying a voltage to both ends of the coil block 120 and adjusting a 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.

Referring to FIGS. 1 and 8, in order to drive the voice coil motor 600, a reverse current (FC) (or initial driving current) is applied to the coil block 120 to drive the bobbin 210. Move to the position.

In one embodiment of the present invention, 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.

At this time, in order to contact the bobbin 210 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 to the coil block 120 When) is applied, the bobbin 210 rapidly descends to the bottom surface 335 of the base 300 and collides with the base 300 and the bobbin 210, thereby reducing the waiting time until the bobbin 210 is stabilized. 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 the specific current amount D applied to the coil block 120 decreases as it approaches the reference position. In order to reduce the waiting time required until the bobbin 210 in contact with the position is stabilized, the reverse current (FC) having a specific current amount (D) first in the coil block 120, as shown in the graph shown by the double-dashed line in FIG. ) Is applied, the specific current amount (D) of the reverse current (FC) is gradually reduced for a predetermined period of time until the bobbin 210 contacts the bottom surface 335 to reduce the descending speed of the bobbin 210. Reduce the waiting time of 210.

Subsequently, the amount of 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 Apply forward current (SC) to. The forward current (SC) can be continuously increased or increased in a stepwise fashion.

Subsequently, 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 corresponds to the optimum focus. Stop at the desired position.

The process of stopping the bobbin 210 at a position corresponding to the optimum focus is a process of additionally moving the bobbin 210 to a position slightly out of the optimum focus position, and a reduction in the amount of forward current in the coil block 120 By doing so, the bobbin 210 may be returned to the optimum focus position, and the fine focus process may be performed to finely adjust the focus between the lens 205 of the bobbin 210 and the image sensor module.

Subsequently, 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 or a moving image of the subject with the optimum focus.

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

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

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

Subsequently, 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 kept constant so that the bobbin 210 corresponds to the optimal focus. Stop at the desired position.

The process of stopping the bobbin 210 at a position corresponding to the optimum focus is a process of moving the bobbin 210 to a position slightly out of the position of the optimum focus, and the reverse current SC is applied to the coil block 120. By slightly increasing the amount of current, the bobbin 210 can be returned to the optimum 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. .

Subsequently, between the image sensor module and the lens 205, the subject and the optimum focus are formed, and the image sensor module generates an image of the subject with the optimum focus.

In the method of driving the voice coil motor according to an embodiment of the present invention, the bobbin 210 shown in FIG. 1 is applied to either the upper surface 320 of the base 300 or the inner surface of the upper plate 510 of the cover can 500. 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 that achieves the optimal focus with the image sensor module, thereby focusing between the mover 200 and the image sensor module. Although the method of adjustment is shown and described, differently, by applying a first current to the coil block 120 to move the bobbin 210 to a reference position, the optimum between the lens 205 and the image sensor module based on the subject It is also possible to calculate data for maintaining focus and apply a current amount of current corresponding to the data 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 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 forward current or a reverse current is applied to the coil block so that the mover including the bobbin is moved from the base. By driving the voice coil motor in both directions in the direction away from or approaching the base, the voice coil motor can be driven with a low current and power consumption can be reduced, the focus between the lens and the image sensor can be adjusted in a shorter time, and contact noise caused by the bobbin can be reduced. It has an effect that can be reduced.

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. Therefore, the true technical protection scope of the present invention should be determined by the following claims.

600...voice coil motor 100...stator
200... mover 300... base
400... lower elastic member 450... upper elastic member
500...cover can

Claims (22)

A cover including an upper plate and a side plate extending from the upper plate;
A housing disposed within the cover;
A bobbin disposed in the cover;
A magnet disposed between the side plate of the cover and the bobbin;
A coil facing the magnet; And
It includes an upper elastic member coupled to the bobbin and the housing,
The upper elastic member includes an inner elastic portion coupled to the bobbin, an outer elastic portion disposed on an upper surface of the housing, and a connection elastic portion connecting the inner elastic portion and the outer elastic portion,
The housing includes a groove overlapping the connection elastic portion of the upper elastic member in a direction of the optical axis and recessed from the upper surface of the housing,
At an initial position where no current is applied to the coil, a first gap is formed between the connection elastic portion of the upper elastic member and the bottom surface of the groove of the housing,
When a reverse driving current is supplied to the coil at the initial position, the first gap decreases due to the movement of the connection elastic portion of the upper elastic member. The method of claim 1,
And a base disposed under the bobbin and coupled to the side plate of the cover,
The upper elastic member supports the bobbin to form a second gap between the bobbin and the base at the initial position,
The voice coil motor moves the bobbin to decrease the second gap in a downward direction approaching the base along an optical axis when a reverse driving current is supplied to the coil at the initial position. The method of claim 1,
In the initial position, the inner elastic portion of the upper elastic member is disposed at a lower position than the outer elastic portion of the upper elastic member. The method of claim 2,
It includes a lower elastic member coupled to the base and the lower portion of the bobbin,
The lower elastic member includes an inner elastic portion coupled to the bobbin, an outer elastic portion coupled to the base, and a connection elastic portion connecting the inner elastic portion and the outer elastic portion,
The upper surface of the base includes a first region overlapping the connection elastic portion of the lower elastic member in the direction of the optical axis,
In the initial position, a third gap is formed between the connection elastic portion of the lower elastic member and the first region of the base,
When a reverse driving current is supplied to the coil at the initial position, the third gap decreases due to the movement of the connection elastic portion of the lower elastic member. The method of claim 4,
The voice coil motor is disposed at a position lower than the outer elastic portion of the lower elastic member, the inner elastic portion of the lower elastic member. 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 at the initial position,
When the forward driving current is supplied to the coil at the initial position, the bobbin moves upward along the optical axis to reduce the fourth gap away from the base. The method of claim 6,
When the bobbin is in a first position in contact with the base, even if the reverse driving current is additionally applied, the bobbin is maintained in the first position,
When the bobbin is in a second position in contact with the cover, the voice coil motor is maintained in the second position even when the forward driving current is additionally applied. The method of claim 2,
The time required for the reverse driving current to be supplied to the coil at the initial position to move the bobbin to the reference position in contact with the base is a voice including the waiting time required for the bobbin to stabilize at the reference position Coil motor. The method of claim 1,
The housing includes a coupling boss formed on the upper surface of the housing,
The voice coil motor including a hole coupled to the coupling boss, the outer elastic part of the upper elastic member. The method of claim 9,
The coupling boss forms a gap between the upper surface of the housing and the upper plate of the cover. The method of claim 1,
At least a portion of the connection elastic portion of the upper elastic member is spaced apart from the upper plate and the housing of the cover. The method of claim 4,
The inner elastic part of the lower elastic member is coupled to the lower surface of the bobbin by adhesive or heat fusion. The method of claim 6,
When the forward driving current is applied to the coil at the initial position, as the bobbin moves upward, the inner elastic part of the upper elastic member is lower than the outer elastic part of the upper elastic member. The voice coil motor is moved to a higher position than the outer elastic portion of the member. The voice coil motor of any one of claims 1 to 13;
A lens coupled to the bobbin of the voice coil motor; And
A camera including an image sensor disposed at a position corresponding to the lens. The method of claim 14,
A camera for moving the bobbin in either an upward or downward direction by adjusting a voltage difference between both ends of the coil. The method of claim 15,
The voltage difference is generated and controlled by a PWM circuit camera. A mobile phone comprising the camera of claim 14. A cover including an upper plate and a side plate extending from the upper plate;
A housing disposed within the cover;
A bobbin disposed in 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
It includes an upper elastic member coupled to the bobbin and the housing,
The upper elastic member includes an inner elastic portion coupled to the bobbin, an outer elastic portion disposed on an upper surface of the housing, and a connection elastic portion connecting the inner elastic portion and the outer elastic portion,
The housing includes a groove overlapping the connection elastic portion of the upper elastic member in a direction of the optical axis and recessed from the upper surface of the housing,
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,
The voice coil motor moves the bobbin to increase the first gap in an upward direction approaching the cover along the optical axis when a positive driving current is supplied to the coil at the initial position. The method of claim 18,
The housing includes a coupling boss formed on the upper surface of the housing,
The voice coil motor including a hole coupled to the coupling boss, the outer elastic part of the upper elastic member. The method of claim 19,
The coupling boss forms a gap between the upper surface of the housing and the upper plate of the cover. The method of claim 18,
In the initial position, the inner elastic portion of the upper elastic member is disposed at a lower position than the outer elastic portion of the upper elastic member. delete

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