KR20220035898A - Voice coil motor and method for driving thereof - Google Patents

Abstract

Voice coil motor base; a bobbin disposed on the base; a stator disposed outside the bobbin; a first driving unit disposed on the stator; a second driving unit disposed on the bobbin and facing the first driving unit; An elastic member coupled to the bobbin; and a position sensor disposed on the stator, wherein the bobbin is moved in a first direction away from the base or in a second direction closer to the base, and the position sensor is configured to move the bobbin in a first direction away from the base. The distance to the upper surface is fixed.

Description

Voice coil motor and driving method thereof {VOICE COIL MOTOR AND METHOD FOR DRIVING THEREOF}

The present invention relates to a voice coil motor and a method of driving the same.

Recently, mobile phones with built-in ultra-small digital cameras have been developed.

Conventionally, in the case of ultra-small digital cameras applied to mobile phones, etc., it was not possible to adjust the gap between the image sensor and lens, which changes external light into a digital image or digital images, but recently, voice coil motors that adjust the gap between the image sensor and lens are used. The same lens driving device was developed, making it possible to obtain improved digital images or digital videos from ultra-small digital cameras.

Generally, a voice coil motor has a lens mounted inside it, and a bobbin placed on the upper surface of the base moves upward from the base to adjust the gap between the lens and the image sensor placed on the back of the base.

Additionally, a leaf spring is coupled to the bobbin of the voice coil motor, so when the voice coil motor is not operating, the bobbin is always in contact with the base due to the elastic force of the leaf spring. That is, the bobbin of a 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, which has the problem of greatly increasing the power consumption of the voice coil motor.

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 on the magnet or bobbin increases, which has the problem of increasing the overall size of the voice coil motor.

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

On the other hand, when power consumption is reduced by separating the bobbin equipped with a lens from the base of the voice coil motor, the position of the bobbin away from the base changes, making it difficult to precisely control the focus, making it difficult to focus continuously, and changing the position of the bobbin. Accordingly, there is a problem in that unnecessary power consumption is consumed.

US Patent Application Publication No. US 2007/0047942 (published March 1, 2007)

The present invention allows low-power operation by separating the lens-mounted mover from the upper surface of the base when a drive signal is not applied and adjusting the gap between the lens and the image sensor by the drive signal, and detects the position of the mover to achieve precise focus. It provides a voice coil motor that allows for precise adjustment and continuous focus adjustment and prevents unnecessary power consumption.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. will be.

In one embodiment, the voice coil motor includes a base; a bobbin disposed on the base; a stator disposed outside the bobbin; a first driving unit disposed on the stator; a second driving unit disposed on the bobbin and facing the first driving unit; An elastic member coupled to the bobbin; and a position sensor disposed on the stator, wherein the bobbin is moved in a first direction away from the base or in a second direction closer to the base, and the position sensor is configured to move the bobbin in a first direction away from the base. The distance to the upper surface is fixed.

According to the voice coil motor and its driving method according to the present invention, a position sensor that senses the displacement of the mover with respect to the stator is mounted on at least one of the stator or the mover that moves with respect to the stator, and the mover is operated by accurately determining the current position of the mover. By driving the ruler, the focusing function can be implemented in a faster time, and it has the effect of significantly reducing power consumption by eliminating unnecessary driving sections of the mover.

1 is a conceptual diagram of a voice coil motor according to an embodiment of the present invention.
Figure 2 is a conceptual diagram of a voice coil motor according to another embodiment of the present invention.
Figure 3 is a conceptual diagram of a voice coil motor according to another embodiment of the present invention.
Figure 4 is a flowchart showing a method of driving a voice coil motor according to an embodiment of the present invention.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the attached drawings. In this process, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. Additionally, 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. The definitions of these terms should be interpreted as meanings and concepts consistent with the technical idea of the present invention based on the content throughout this specification.

1 is a conceptual diagram of a voice coil motor according to an embodiment of the present invention.

Referring to FIG. 1, the voice coil motor 100 includes a base 110, a stator 120, a mover 130, an elastic member 140, and a position sensor 150.

The base 110 serves to support the stator 120 and the mover 130.

*25 An opening is formed in the base 110 that penetrates the upper and lower surfaces of the base 110, and the opening is formed in a position corresponding to the lens 132 of the mover 130, which will be described later. An image sensor 115 that generates a digital image or video corresponding to light incident through the aperture may be disposed on or behind the base 110.

The stator 120 is placed on the base 110 and the stator 120 is not driven.

The fixed stator 120 includes a first driving unit 125 for driving a mover 130, which will be described later, and the first driving unit 125 generates a first magnetic field. In one embodiment of the present invention, the first driving unit 125 may include a plurality of magnets.

The mover 130 is disposed inside the stator 120, and the mover 130 includes a lens 132, a bobbin 134, and a second driving unit 136.

The bobbin 134 of the mover 130 is, for example, formed in a cylindrical shape with upper and lower surfaces open, and the lens 132 is coupled to the inner surface of the bobbin 134. For example, the lens 132 may be coupled to the inner surface of the bobbin 134 using a screw method.

The second driving unit 136 is disposed on the outer surface of the bobbin 134. In one embodiment of the present invention, the second driving unit 136 may include a coil block. A coil block is formed by winding a long wire insulated or coated with insulating resin.

The coil block may be wound in a cylindrical shape and placed on the outer surface of the bobbin 134, or may be wound directly on the outer surface of the bobbin 134.

The second driving unit 136 including a coil block reacts with the first magnetic field by a driving signal such as a current to generate a second magnetic field that generates attractive or repulsive force.

The elastic member 140 is coupled to the stator 120 and the mover 130 and serves to elastically support the mover 130.

In one embodiment of the present invention, the elastic member 140 may include, for example, a leaf spring, and the elastic member 140 is coupled to the lower and upper portions of the bobbin 134 of the mover 130, respectively. It can be.

In one embodiment of the present invention, the mover 130 elastically coupled to the elastic member 140 moves the upper surface of the base 110 when a drive signal is not applied to the second drive unit 136 including the coil block. It is spaced a predetermined distance from.

When the mover 130 is separated from the upper surface of the base 110, the mover 130 moves away from the upper surface of the base 110 or Bidirectional driving is possible in a direction approaching the upper surface of the base 110, and as a result, the voice coil motor 100 can be driven at a low current and greatly reduce power consumption.

On the other hand, when the mover 130 is separated from the upper surface of the base 110, that is, when the mover 130 floats from the upper surface of the base 110, the reference position of the mover 130 or the position of the mover 130 It is difficult for the control unit to determine the current position, and as a result, the mover 130 may be driven unnecessarily, resulting in unnecessary power consumption.

In one embodiment of the present invention, the position sensor 150 is disposed on the second driving part 136 including a coil block, facing the first driving part 125 including a magnet.

The position sensor 150 outputs a sensing signal for the reference position and/or the current position of the mover 130 to the control unit (not shown), and the control unit detects the coil block in response to the sensing signal output from the position sensor 150. A suitable driving signal is provided to the second driving unit 136 including.

In one embodiment of the present invention, the position sensor 150 is a Hall sensor, which is one of the magnet sensors suitable for sensing the position of the mover 130 according to changes in the magnetic field, and is connected to the Hall sensor to provide driving power. It includes a wire that applies and outputs a sensing signal, and the wire may be electrically connected to a circuit board disposed on the rear of the base 110 to generate a driving signal.

Considering the production cost, one position sensor 150 may be placed on the second driving unit 136. Alternatively, a plurality of position sensors 150 may be placed on the second driving unit 136 at equal intervals.

Figure 2 is a conceptual diagram of a voice coil motor according to another embodiment of the present invention. A voice coil motor according to another embodiment of the present invention has substantially the same configuration as the voice coil motor previously described in FIG. 1 except for the arrangement of the first and second driving units and the position sensor. Therefore, duplicate descriptions of the same components will be omitted, and the same components will be given the same names and same reference numerals.

Referring to FIG. 2 , the voice coil motor 100 includes a base 110, a stator 120, a mover 130, an elastic member 140, and a position sensor 160.

The stator 120 includes a first driving part 127 that generates a first magnetic field. In one embodiment of the present invention, the first driving part 127 is a long wire insulated by an insulating resin wound into a cylindrical shape. It may include a coil block.

In addition, a second driving unit 138 is disposed on the outer peripheral surface of the bobbin 134 of the mover 130 disposed inside the stator 120 to generate a second magnetic field that reacts with the first magnetic field to generate an attractive or repulsive force. do.

In one embodiment of the present invention, the second driving unit 138 facing the first driving unit 127 including a coil block may include a plurality of magnets.

The position sensor 160 may be, for example, a Hall sensor, and the position sensor 160 may be disposed on the inner surface of the first driving part 127, which faces the second driving part 138 and includes a coil block. there is.

The position sensor 160 senses a change in the second magnetic field generated from the second driving unit 138 according to the movement of the mover 130 and outputs a sensing signal corresponding to the current position of the mover 130.

The position sensor 160 outputs a sensing signal for the reference position and/or the current position of the mover 130 to the control unit (not shown), and the control unit detects the coil block in response to the sensing signal output from the position sensor 160. A suitable driving signal is provided to the first driving unit 127 including.

Figure 3 is a conceptual diagram of a voice coil motor according to another embodiment of the present invention. A voice coil motor according to another embodiment of the present invention has substantially the same configuration as the voice coil motor previously described in FIG. 1 except for the arrangement of the elastic member and the mover. Therefore, duplicate descriptions of the same components will be omitted, and the same components will be given the same names and same reference numerals.

Referring to FIG. 3, the voice coil motor 100 includes a base 110, a stator 120, a mover 130, an elastic member 145, and a position sensor 150.

The stator 120 includes a first driver 125, and the first driver 125 includes at least one magnet that generates a first magnetic field.

The mover 130 is disposed inside the stator 120, and the mover 130 includes a second drive part 136 facing the first drive part 125. The second driver 136 includes a coil block wound with a long insulated wire, and the second driver 136 generates a second magnetic field that acts on the first magnetic field to generate an attractive or repulsive force.

The elastic member 145 is coupled to the mover 130 and the stator 120, and the mover 130 is elastically coupled to the elastic member 145.

In one embodiment of the present invention, the mover 130 coupled to the elastic member 145 is in contact with the upper surface of the base 110 when a drive signal is not applied to the second drive unit 136, and the mover 130 ) is spaced apart from the upper surface of the base 110 when a driving signal is applied to the second driving unit 136.

The position sensor 150 is, for example, disposed on the second driving unit 136, and the position sensor 150 senses changes in the magnetic field generated as the mover 130 is spaced from the upper surface of the base 110. to output a sensing signal.

The position sensor 150 outputs a sensing signal for the reference position and/or the current position of the mover 130 to the control unit (not shown), and the control unit detects the coil block in response to the sensing signal output from the position sensor 150. A suitable driving signal is provided to the second driving unit 136 including.

Figure 4 is a flowchart showing a method of driving a voice coil motor according to an embodiment of the present invention.

Referring to FIGS. 1 and 4 , in order to drive the voice coil motor 100, a step of first sensing the reference position or current position of the mover 130 having the lens 132 through the position sensor 150 is performed. (Step S10)

Specifically, the position sensor 150 is disposed on the base 110 and moves up and down with respect to the stator 120 and the stator 120 having the first driving part 125 and the mover having the second driving part 136. It is placed in any one of (130).

For example, when the first driver 125 includes a magnet and the second driver 136 includes a coil block, the position sensor 150, such as a Hall sensor, is connected to the first driver 125. It is disposed on the second driving unit 136 facing.

Conversely, when the first driver 125 includes a coil block and the second driver 136 includes a magnet, the position sensor 150 is attached to the first driver 125 facing the second driver 136. It is placed.

At this time, when a driving signal is not applied to the first and second driving units 125 and 136, the mover 130 may be spaced apart from the upper surface of the base 110 and may be floating.

Alternatively, when a driving signal is not applied to the first and second driving units 125 and 136, the mover 130 may be disposed on the upper surface of the base 110.

Next, the sensing signal generated from the position sensor 150 is applied to the control unit, and the control unit determines the current position of the mover 130 in response to the sensing signal generated from the position sensor 150 (step S20).

Next, the control unit determines the level of a drive signal to adjust the gap between the lens and the image sensor included in the mover 130 based on the sensing signal generated from the position sensor 150 (step S30).

Next, the control unit adjusts the gap between the lens and the image sensor by applying a driving signal to one of the first and second driving units 125 and 136 (step S40).

As explained in detail above, a position sensor that senses the displacement of the mover with respect to the stator is mounted on at least one of the stator or the mover that moves with respect to the stator, and the current position of the mover is accurately determined to drive the mover to perform a focusing function. It can be implemented in a faster time and has the effect of significantly reducing power consumption by eliminating unnecessary driving sections of the operator.

Although embodiments according to the present invention have been described above, they are merely illustrative, and those skilled in the art will understand that various modifications and equivalent scope of embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the following patent claims.

Claims (18)

Base;
a bobbin disposed on the base;
An elastic member coupled to the bobbin;
a stator disposed outside the bobbin;
a first driving unit disposed on the stator;
a second driving unit disposed on the bobbin and facing the first driving unit; and
It includes a position sensor disposed on the stator,
The bobbin is moved in a first direction away from the base or in a second direction closer to the base,
The position sensor maintains a fixed distance to the upper surface of the base even if the bobbin moves,
The inner surface of the position sensor protrudes inward than the inner surface of the first driving unit,
The elastic member includes a first elastic member disposed between an upper portion of the bobbin and the stator to support the bobbin, and a second elastic member disposed between a lower portion of the bobbin and the stator to support the bobbin, The position sensor is disposed between the first elastic member and the second elastic member,
The first elastic member and the second elastic member each include a first region coupled to the bobbin,
In an initial position where no current is applied to the first driving unit or the second driving unit, the bobbin is elastically supported by the elastic member,
As the bobbin moves, the position sensor moves closer to or farther away from either the first area of the first elastic member or the first area of the second elastic member.
According to paragraph 1,
The first driving unit includes a coil,
The second driving unit is a voice coil motor including a magnet.
According to paragraph 1,
The position sensor is a voice coil motor including a Hall sensor that detects changes in a magnetic field, and a wire electrically connected to the Hall sensor and disposed on the bottom of the base to supply external power.
According to paragraph 2,
A voice coil motor in which the direction of current applied to the coil when the bobbin moves in the first direction and the direction of current applied to the coil when the bobbin moves in the second direction are opposite to each other.
According to paragraph 2,
A voice coil motor further comprising a control unit that provides a driving signal to the coil in response to a sensing signal from the position sensor.
According to paragraph 2,
A voice coil motor in which a plurality of position sensors are disposed at equal intervals on the surface of the coil.
According to paragraph 1,
A voice coil motor comprising a cover including a top plate and a side plate extending from the top plate and coupled to the base.
In clause 7,
The position sensor is a voice coil motor disposed between the second driving unit and the side plate.
According to clause 6,
The coil is wound in a cylindrical shape on the inner surface of the stator to form a coil block, the coil block has an upper surface, an inner surface, and a lower surface, and the lower surface of the coil is disposed to face the base, A voice coil motor where the upper surface of the coil block is disposed to face the cover.
According to clause 6,
The elastic member forms a first gap between the base and the bobbin and a second gap between the bobbin and the cover at an initial position where no current is applied to the coil.
Base;
a bobbin disposed on the base;
a stator disposed outside the bobbin;
An elastic member coupled to the bobbin;
a first driving unit disposed on the bobbin;
a second driving unit disposed outside the first driving unit;
Including a position sensor disposed on the bobbin,
The bobbin is moved in a first direction away from the base or in a second direction closer to the base,
The outer surface of the position sensor protrudes outward than the outer surface of the first driving unit,
The elastic member includes a first elastic member disposed between an upper portion of the bobbin and the stator to support the bobbin, and a second elastic member disposed between a lower portion of the bobbin and the stator to support the bobbin, The position sensor is disposed between the first elastic member and the second elastic member,
The first elastic member and the second elastic member each include a first region coupled to the bobbin,
In an initial position where no current is applied to the first driving unit or the second driving unit, the bobbin is elastically supported by the elastic member,
A voice coil motor in which the position sensor has a fixed optical axis distance between the first area of the first elastic member and the first area of the second elastic member even if the bobbin is moved.
According to clause 11,
The position sensor is a voice coil motor including a Hall sensor that detects changes in a magnetic field, and a wire electrically connected to the Hall sensor and disposed on the bottom of the base to supply external power.
According to clause 11,
A current direction applied to the first driving unit or the second driving unit when the bobbin moves in the first direction, and a current direction applied to the first driving unit or the second driving unit when the bobbin moves in the second direction. are opposing voice coil motors.
According to clause 11,
A voice coil motor including a control unit that provides a driving signal to the first driving unit or the second driving unit in response to a sensing signal from the position sensor.
According to clause 11,
A voice coil motor comprising a cover including a top plate and a side plate extending from the top plate and coupled to the base.
According to clause 11,
The position sensor is a voice coil motor disposed between one of the first driving unit and the second driving unit and the side plate.
According to clause 11,
A voice coil motor in which, in an initial position where no current is applied to the first driving unit or the second driving unit, the bobbin is elastically supported by the elastic member and disposed between the base and the cover.
According to clause 11,
The elastic member forms a first gap between the base and the bobbin and a second gap between the bobbin and the cover at an initial position where no current is applied to the first driving unit or the second driving unit. .