KR20240079199A - Voice coil motor - Google Patents

Abstract

The voice coil motor includes a stator including a first driving unit; a mover disposed inside the stator, including a second driving part that reacts with the first driving part, and having a lens mounted therein; a base for fixing the stator; and an elastic member coupled to the mover to space the mover away from the base when a driving signal is not applied to the first or second driving unit, wherein the mover moves in a first direction toward the base or toward the base. It is moved in a second direction away from the base, and a first stroke length of the mover in the first direction and a second stroke length of the mover in the second direction are formed to be different from each other.

Description

Voice coil motor {VOICE COIL MOTOR}

The present invention relates to voice coil motors.

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 base moves from the base to the top 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 upper surface of the base due to the elastic force of the leaf spring. That is, the bobbin of a conventional voice coil motor is driven in only one direction 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.

(Patent Document 1) JP2008-281863 A

The present invention provides a voice coil motor that allows the mover to be driven in both directions with a smaller current by floating the mover from the base, and further reduces power consumption when using an infinite focusing area.

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 stator including a first driving unit; a mover disposed inside the stator, including a second driving part that reacts with the first driving part, and having a lens mounted therein; a base for fixing the stator; and an elastic member coupled to the mover to space the mover away from the base when a driving signal is not applied to the first or second driving unit, wherein the mover moves in a first direction toward the base or toward the base. It is moved in a second direction away from the base, and a first stroke length of the mover in the first direction and a second stroke length of the mover in the second direction are formed to be different from each other.

In one embodiment, the voice coil motor includes a stator including a first driving unit; a mover disposed inside the stator, including a second driving part that reacts with the first driving part, and having a lens mounted therein; a base for fixing the stator; and an elastic member coupled to the mover to space the mover away from the base when a driving signal is not applied to the first or second driving unit, wherein the mover moves in a first direction toward the base or toward the base. Moved in a second direction away from the base, the first center bisecting the upper and lower surfaces of the mover and the second central portion bisecting the distance between the upper surface of the base and the inner surface of the cover facing the base are formed to be offset. do.

According to the voice coil motor according to the present invention, the mover is allowed to float from the top surface of the base when no drive signal is applied, and the stroke length or gap between the floated mover and the top surface of the base is between the floated mover and the cover. Low current or low power consumption characteristics can be realized by forming different stroke lengths or gaps.

1 is a cross-sectional view of a voice coil motor according to an embodiment of the present invention.
FIG. 2 is a graph showing current-distance characteristics of the voice coil motor of FIG. 1.
FIG. 3 is a cross-sectional view showing the voice coil motor of FIG. 1 in an inverted state.
Figure 4 is a cross-sectional view of a voice coil motor according to another 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 cross-sectional view of a voice coil motor according to an embodiment of the present invention. FIG. 2 is a graph showing current-distance characteristics of the voice coil motor of FIG. 1.

1 and 2, the voice coil motor 100 includes a base 110, a stator 120, a mover 130, an elastic member 140, and a cover 150.

The base 110 is formed in the shape of a plate with an opening formed in the center, and serves as a lower stopper of the mover 130.

A receiving groove may be formed on the upper surface of the base 110 to accommodate the lower surface of the movable element 130 in order to separate the upper surface of the base 110 from the lower surface of the movable element 130 .

A shock absorbing member 115 is disposed on the upper surface of the base 110 to prevent the mover 130 and the base 110 from colliding and generating noise. The shock absorbing member 115 may include, for example, any one of sponge, synthetic resin having elasticity, and rubber.

The stator 120 is fixed on the base 110, and the stator 120 includes a first driving unit 125 that generates a magnetic field, and a storage space is formed inside the stator 120.

In one embodiment of the present invention, the first driver 125 may include, for example, a coil formed by winding a long wire insulated with an insulating resin to generate a magnetic field by current. Alternatively, the first driving unit 125 may include a magnet that generates a magnetic field. In one embodiment of the present invention, the first driving unit 125 of the stator 120 includes a coil.

The mover 130 is disposed inside the stator 120 and includes a lens 135. A second driving unit 138 that generates a magnetic field is mounted on the outer surface of the mover 130.

In one embodiment of the present invention, when the first driving part 125 of the stator 120 includes a coil, the second driving part 138 of the mover 130 may include a magnet. Alternatively, when the first driving part 125 of the stator 120 includes a magnet, the second driving part 138 of the mover 130 may include a coil. In one embodiment of the present invention, the second driving unit 138 of the mover 130 includes, for example, a magnet.

One side of the elastic member 140 is fixed to the mover 130 and the other side opposite to the one side is fixed to the stator 120, and the elastic member 140 elastically supports the mover 130.

In one embodiment of the present invention, the elastic member 140 includes a first elastic member 143 formed at the bottom of the outer circumference of the mover 130 and a second elastic member 146 formed at the top of the outer circumference of the mover 130. It can be included.

The elastic member 140 moves the mover 130 to the upper surface of the base 110 when a drive signal is not applied to the first drive part 125 of the stator 120 or the second drive part 138 of the mover 130. keep away from

The cover 150 is fixed to the base 110, and the cover 150 surrounds the stator 120 and the mover 130. Additionally, the cover 150 serves as an upper stopper to stop the mover 130.

A shock absorbing member 155 is disposed on the cover 150 to prevent the mover 130 and the cover 150 from colliding and generating noise. The shock absorbing member 155 may include, for example, any one of sponge, synthetic resin having elasticity, and rubber.

In a state where the mover 130 is spaced apart from the upper surface of the base 110 by the elastic member 140, either the first driving part 125 of the stator 120 or the second driving part 138 of the mover 130 As a drive signal is applied to one, the mover 130 moves in a direction toward the base 110 or toward the cover 150. As a result, the gap between the lens 135 disposed inside the mover 130 and the image sensor disposed behind the base 110 is adjusted, and external light passing through the lens is focused on the image sensor.

Referring again to Figures 1 and 2, in one embodiment of the present invention, when a driving signal is not applied to the first driving part 125 of the stator 120 or the second driving part 138 of the mover 130 , the first stroke length SD1 formed by the base 110 and the lower surface of the mover 130 is shorter than the second stroke length SD2 formed by the cover 150 and the upper surface of the mover 130.

The reason why the first stroke length (SD1) is formed shorter than the second stroke length (SD2) like this is because users mainly take pictures using the infinite focus of the camera module and only in special cases take pictures using a specific focus. Because.

Referring to the graph of FIG. 2, to implement the frequently used infinity focus (distance from subject 1 m to 50 m) between the image sensor disposed at the rear of the base 110 and the lens 135 of the mover 130. To this end, the mover 130 floating in a stationary state from the base 110 moves to the base by a drive signal applied to the first drive part 125 of the stator 120 or the second drive part 138 of the mover 130. While moving in the downward direction toward the upper surface of 110, the mover 130 contacts the upper surface of the base 110, which is the lower stopper.

At this time, the space between the lower surface of the mover 130 in the floating stationary state and the upper surface of the base 110 has a first stroke length SD1, and the mover 130 uses the stator to contact the upper surface of the base 110. The amount of current applied to (120) is C[mA].

Meanwhile, in order to implement infinity focus, a current of D[mA] (where D>C) is applied again to the stator 120, and as a result, the mover 130 is spaced away from the upper surface of the base 110 and moves to the infinity focus position. is placed in The mover 130 corresponding to the infinity focus position is spaced approximately 40㎛ apart from the upper surface of the base 110, similar to the comparative example described above.

Meanwhile, when performing close-up photography, a current of E [mA] is applied to the first driving part 125 of the stator 120 or the second driving part 138 of the mover 130, and the mover 130 ) is in contact with the cover 150, which is the upper stopper. At this time, the space between the upper surface of the mover 130 in the floating stationary state and the cover 150 has a second stroke length (SD2) that is longer than the first stroke length (SD1).

Referring to Figure 2, in one embodiment of the present invention, the mover 130 first descends toward the base 110 by about 100㎛, and then moves the mover 130 about 100㎛ by about 9 [mA]. A current of about 10 [mA] is required.

As a result, in order to implement the mover 130 with low current and low power consumption when implementing the infinite focus frequently used by users, the first stroke length (SD1) between the mover 130 and the base 110 is covered. It is preferable to make it shorter than the second stroke length (SD2) between (150) and the mover (130).

In one embodiment of the present invention, the length of the second stroke length SD2 may be two to three times the first stroke length SD1 based on the first stroke length SD1.

Conversely, when the user frequently implements close-up focus, in order to implement the mover 130 with low current and low power consumption, the first stroke length (SD1) between the mover 130 and the base 110 is adjusted to the cover 150. And it may be formed to be longer than the second stroke length (SD2) between the movers 130.

That is, in one embodiment of the present invention, the first stroke length (SD1) between the mover 130 and the base 110 and the second stroke length between the cover 150 and the mover 130 are determined by the user's selection or inclination. The stroke length (SD2) can be formed differently.

In one embodiment of the present invention, the first stroke length SD1 and the second stroke length SD2 may be changed depending on the posture of the voice coil motor 100.

For example, when the base 110 is placed facing the ground as shown in FIG. 1, the elastic member 140 sags toward the upper surface of the base 110 due to the weight of the mover 130. This reduces the first stroke length SD1 between the mover 130 and the base 110 and increases the second stroke length SD2 between the mover 130 and the cover 150, but even in this case, The first stroke length SD1 is formed to be shorter than the second stroke length SD2.

FIG. 3 is a cross-sectional view showing the voice coil motor of FIG. 1 in an inverted state.

As shown in FIG. 3, when the cover 150 is placed facing the ground, the elastic member 140 sags toward the cover 150 due to the self-weight of the mover 130, which causes the mover 130 ) and the first stroke length (SD1) between the base 110 is increased and the second stroke length (SD2) between the mover 130 and the cover 150 is decreased, but even in this case, the first stroke length (SD1) ) is formed to have a length shorter than the second stroke length (SD2).

That is, in one embodiment of the present invention, the first stroke length SD1 is a length including the sagging length of the mover 130.

Figure 4 is a conceptual diagram showing a voice coil motor according to another embodiment of the present invention.

Referring to FIG. 4 , the voice coil motor 100 includes a base 110, a stator 120, a mover 130, an elastic member 140, and a cover 150.

A stator 120 is disposed on the base 110, and a mover 130 coupled to the lens 135 is disposed on the base 110 corresponding to the inside of the stator 120.

The elastic member 140 supports the stator 120 and the mover 130 so that the mover 130 floats from the upper surface of the base 110 when a driving signal such as current is not applied to the stator 120 and the mover 130. 130), and the cover 150 is coupled to the base 110.

Hereinafter, the position of the center of the upper and lower surfaces of the mover 130 will be defined as the first center 130a, and the position that bisects the lower surface of the cover 150 and the upper surface of the base 110 will be defined as the second center 130b. ) is defined as.

In one embodiment of the present invention, in order to implement low current characteristics and low power consumption characteristics when infinity focus is frequently used, the first center 130a, which is a position that bisects the upper and lower surfaces of the mover 130, is covered ( It is disposed lower than the second central portion 130b, which bisects the lower surface of the base 150 and the upper surface of the base 110.

In this way, the first center 130a, which bisects the upper and lower surfaces of the mover 130, is placed lower than the second central center 130b, which bisects the lower surface of the cover 150 and the upper surface of the base 110. The first gap G1 formed between the base 110 and the mover 130 is narrower than the second gap G2 formed between the mover 130 and the cover 150.

In addition, in one embodiment of the present invention, the first gap G1 formed between the base 110 and the mover 130 is the second gap G2 formed between the mover 130 and the cover 150. It can be formed two to three times narrower.

According to the detailed description above, when the drive signal is not applied, the mover is allowed to float from the top surface of the base, and the stroke length or gap between the floating mover and the top surface of the base is the stroke length between the floated mover and the cover. Alternatively, it can be formed differently from the gap to implement low current or low power consumption characteristics.

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.

100...voice coil motor 110...base
120...stator 130...mover
140...elastic member 150...cover

Claims (20)

A cover including a top plate and side plates extending from the top plate;
a bobbin disposed within the cover;
a base disposed below 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
Includes an elastic member coupled to the bobbin,
The elastic member separates the bobbin from the base at an initial position where no current is applied to the coil,
When a first drive current is applied to the coil, the bobbin moves from the initial position in a first direction away from the base,
When a second driving current is applied to the coil, the bobbin moves from the initial position in a second direction approaching the base,
The movement section of the bobbin is a first section in which the bobbin moves from the initial position in the first direction away from the base and a second section in which the bobbin moves in the second direction approaching the base from the initial position. Including,
A lens driving device in which the length of the first section is two to three times longer than the length of the second section. According to paragraph 1,
A first gap is formed between the base and the bobbin at the initial position,
A second gap is formed between the bobbin and the cover at the initial position,
The first gap is smaller than the second gap. According to paragraph 1,
It includes a first center portion that is the center position of the upper and lower surfaces of the bobbin in the optical axis direction,
A second center portion is located at the center of the lower surface of the upper plate of the cover and the upper surface of the base in the optical axis direction,
The first center portion is closer to the upper surface of the base than the second center portion. According to paragraph 1,
In the movement section of the bobbin, the first section is the distance from the initial position until the bobbin contacts the inner surface of the upper plate of the cover,
The second section is the distance from the initial position until the bobbin contacts the upper surface of the base. According to paragraph 1,
The lens driving device wherein the upper plate of the cover limits the moving distance of the bobbin in the first direction. According to paragraph 1,
The base is a lens driving device that limits the moving distance of the bobbin in the second direction. According to paragraph 1,
A lens driving device wherein the distance between the lower surface of the bobbin and the upper surface of the base is shorter than the distance between the upper surface of the bobbin and the inner surface of the upper plate of the cover. According to paragraph 1,
The lower surface of the bobbin and the upper surface of the base are areas in contact with each other,
A lens driving device in which the upper surface of the bobbin and the inner surface of the upper plate of the cover are areas in contact with each other. According to paragraph 1,
The bobbin overlaps the upper plate of the cover in the optical axis direction,
A lens driving device wherein the bobbin overlaps the base in the optical axis direction. According to paragraph 1,
The base includes a lower stopper brought into contact with the bobbin by movement of the bobbin,
The cover is a lens driving device including an upper stopper brought into contact with the bobbin by movement of the bobbin. According to paragraph 1,
The cover is a lens driving device arranged to surround the bobbin, the coil, and the magnet. According to paragraph 1,
A lens driving device in which a shock absorbing member in contact with the bobbin is disposed on the upper surface of the base. According to paragraph 1,
A lens driving device in which a shock absorbing member in contact with the bobbin is disposed on an inner surface of the upper plate of the cover. According to paragraph 1,
A first imaginary line dividing the second imaginary line connecting the upper surface of the bobbin to the lower surface of the bobbin into two is a third imaginary line dividing into two the fourth imaginary line connecting the upper surface of the base to the inner surface of the upper plate of the cover, and separated,
The second imaginary line and the fourth imaginary line are parallel to the first direction,
The first imaginary line is closer to the base than the third imaginary line. According to paragraph 1,
A lens driving device in which the bobbin is spaced apart from the base at a position for implementing infinity focus. image sensor;
The lens driving device of claim 1; and
A camera including a lens coupled to the bobbin of the lens driving device. A mobile phone containing the camera of claim 16. A cover including a top plate and side plates extending from the top plate;
a bobbin disposed within the cover;
a base disposed below 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
Includes an elastic member coupled to the bobbin,
The bobbin is spaced apart from the base in an initial position where no current is applied to the coil,
When a first drive current is applied to the coil, the bobbin moves from the initial position in a first direction away from the base,
When a second driving current is applied to the coil, the bobbin moves from the initial position in a second direction approaching the base,
The movement section of the bobbin includes a first section in which the bobbin moves from the initial position in a first direction away from the base and a second section in which the bobbin moves in a second direction approaching the base from the initial position. do,
The first driving current and the second driving current applied to the coil have opposite polarities,
A lens driving device in which the length of the first section is two to three times longer than the length of the second section. According to clause 18,
A first gap is formed between the base and the bobbin at the initial position,
A second gap is formed between the bobbin and the cover at the initial position,
The first gap is smaller than the second gap. A cover including a top plate and side plates extending from the top plate;
a base coupled to the side plate of the cover;
a bobbin disposed between the top and the base of the cover;
a coil disposed on the bobbin;
a magnet facing the coil; and
Includes an elastic member coupled to the bobbin,
A lens driving device wherein the bobbin is spaced apart from the base and the upper plate of the cover in an initial position where no current is applied to the coil.