JP2007206334A - Lens actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens actuator which has high magnetic efficiency with a simple structure and whose thickness is restrained to be thin. <P>SOLUTION: The opening parts of the U-shaped cross sections of two ring type yokes having the U-shaped cross section and composed of magnetic substance are opposed, and a magnet magnetized in an optical axis direction is provided on one yoke, and a field coil is wound round the other yoke inside the U-shaped cross sections of the two yokes, whereby magnetic flux concentrated at the ends of the U-shapes of both yokes is used as driving force. By using the inner wall of a housing for the guide of a driving part, the thickness is restrained to be thin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a lens actuator used by being mounted on a camera-equipped mobile phone or the like.

At present, the lens actuator of a camera mounted on a mobile phone or the like has a structure that drives a lens in the optical axis direction from a rotational movement through a screw part, and a lens drive in the optical axis direction directly by a magnetic force. It is roughly divided into what to do.

Among these, the former has been used for a lens barrel of a camera for a long time, and Japanese Patent Application Laid-Open No. 62-267711 (hereinafter referred to as Reference 1) has been filed and published.

In the cited document 1, a field coil is sandwiched between two yokes to form a stator, and a multi-pole magnetized rotor magnet is arranged close to the inner periphery of the stator.

With the above-described configuration, in the lens actuator described in Cited Document 1, the magnetic flux generated by the field coil is concentrated at the end of the stator during driving, and different magnetic poles are formed alternately.

With this configuration, the magnetic poles at the end of the stator are switched by switching the field coil, so that the magnetic force acting between the rotor magnet and the stator changes corresponding to the switching of the magnetic poles, and the rotor magnet rotates. ing.

In the cited document 1, using the above driving principle, a lens provided on the inner periphery of the rotor magnet via a screw portion is rotated by the rotor magnet to move the lens in the optical axis direction.

By using such a structure in which the lens portion moves in the optical axis direction through the screw portion, the lens actuator described in the cited document 1 performs the lens movement in the optical axis direction and the fixing after the lens position adjustment. It is possible to do at the same time.

In Cited Document 1, since the lens unit is moved in the optical axis direction by rotational driving, there is an advantage that the lens does not move with respect to an external force in the optical axis direction.

Further, since the lens is driven by a predetermined angle because of step driving, the focus adjustment can be easily performed.

A lens actuator that directly drives the lens in the direction of the optical axis by the above-described magnetic force with respect to the rotationally driven lens actuator as described above has been filed and disclosed as Japanese Patent Application Laid-Open No. 2003-149529 (hereinafter referred to as Citation 2). .

This is a structure that has an advantage with respect to the problem of an increase in the number of assembling steps that the rotational drive type lens actuator represented by the cited document 1 has in its structure.

That is, as the mobile terminal is further downsized, the rotational drive type represented by the above cited reference 1 needs to be provided with a threaded portion on the outer periphery of the lens due to its structure. There was a problem that man-hours were required.

In addition, since the lens is fixed after adjusting the focal position, it is not necessary to return to the origin, and it is necessary to input a signal for returning to the origin after photographing.

With respect to such a problem, the linear drive type lens actuator represented by the cited document 2 does not need to be provided with a threaded portion, facilitates assembly, and simplifies the component shape. It is possible to cope with downsizing of the portable terminal by downsizing each component.

The linear drive type lens actuator typified by Patent Document 2 has a structure in which the lens is driven by using the mutual magnetic force acting between the coil and the magnet, so that the cost can be kept low in mass production. There is an advantage that the number of parts can be reduced.

Further, since the magnetic flux is generated by applying a voltage to the coil, it can be automatically returned to the original position by the magnetic force acting on the magnetic material when not energized.

In addition to the above-described advantages, in Cited Document 2, the magnetic material between the field coil and the magnet is weakened as the driving unit moves away from the coil by making the plate made of a magnetic material provided in the driving unit into a triangular shape. The structure which solves a subject and the drive part which provided the lens with constant magnetic force always moves is set.

Furthermore, since the drive unit and the fixed unit are fitted and configured, the movement of the drive unit is limited in the optical axis direction, and it is possible to reduce blurring of the optical axis as a whole.

In addition, by providing one set of inner and outer drive units for the outer peripheral surface and inner peripheral surface of the magnet having a cylindrical shape, the two lenses can be moved independently in the optical axis direction.

For this reason, it can be used not only for focus adjustment but also as a zoom optical system, and there is an advantage that the entire apparatus used in the photographing apparatus can be easily downsized.

In addition to the advantages listed above, the lens actuator described in the cited document 2 is fixed with a magnetic force acting between the magnetic plate and the magnet when no current is applied, and the lens is already in a state where one lens is fixed. Since one lens can be driven, it is possible to save power in the entire apparatus.

JP 62-267711 A JP2003-149529

However, the lens actuator described in the cited document 2 has a problem that it is difficult to reduce the thickness because the inner periphery and the outer periphery of the cylindrical magnet are used, and the magnetic efficiency is reduced with respect to the magnetic flux of the magnet. ing.

In addition, since it has a structure in which a drive unit having a coil is covered with a magnet, it is necessary to provide a separate housing for holding the drive unit. It will increase.

Further, since the thickness necessary for mounting the lens actuator is determined by the height of the magnet and the driving range, unlike the lens actuator in which the driving unit is provided inside the cylinder as in the cited reference 1, the part itself It is necessary to add the dimension of the lens driving range to the dimension.

In order to solve the above-described problems, an object of the present invention is to provide a lens actuator that has a simple structure, has high magnetic efficiency, and can be reduced in thickness.

In order to solve the above-mentioned problems, the invention according to claim 1 includes first and second yokes formed in a ring shape having a U-shaped cross section, which is made of a magnetic material,
The first yoke is formed on the radially inner circumferential side of the ring shape with an opening having a U-shaped cross section,
The second yoke is formed on the radially outer peripheral side of the ring shape with an opening having a U-shaped cross section facing it,
A lens is fixed to the inner periphery of the second yoke;
The U-shaped end portions of the two yokes are arranged so that the openings of the two yokes face each other.
Further, a magnet magnetized in the optical axis direction of the lens is disposed inside one of the U-shaped cross sections of the two yokes,
A field coil wound around the optical axis direction of a lens fixed to the second yoke is disposed inside the U-shaped cross section of the other yoke, respectively. Yes.

In Claim 2, of the components constituting the lens actuator according to Claim 1,
Regarding the housing for housing the first and second yokes, magnets, field coils, and lenses,
In the movable range when the lens is driven in the optical axis direction of the second yoke having the lens fixed to the inner periphery,
It is characterized in that at least a part of the inner wall of the housing is formed in contact with the outer periphery of the second yoke.

According to the first aspect of the present invention, components can be arranged concentrically around the optical axis of the lens, and the lens actuator can be made thin.

The lens actuator of the present invention is characterized in that an annular yoke having a U-shaped cross section is arranged so that the openings face each other. The inner circumference of each yoke has a magnet on one side and a field coil on the other side. When the field coil is energized, the magnetic flux concentrates at the opening end of each other, and the inner circumference has a lens by mutual magnetic force. The drive unit on the side moves in the optical axis direction.

By using this structure, the lens actuator of the present invention can suppress the reduction in magnetic force with high magnetic efficiency even when the thickness is reduced by reducing the dimension in the thickness direction.

In addition, the magnetic yoke produces a high magnetic efficiency by concentrating the magnetic flux generated from both the field coil and the magnet on both poles of the U-shaped end of the yoke. Magnetic attraction force is generated between the U-shaped end of the yoke fixed inside the U-shaped section and the U-shaped end of the yoke fixed with the magnet inside the U-shaped section. The drive unit can be returned to the origin without being supported by a suspension or the like.

In the present invention, at the time of driving, the magnetic force generated at both ends of the U-shape with respect to the magnetic pole is used at the same time. For this reason, it is possible to drive the lens even when the number of turns of the field coil is reduced due to a thin magnet and a small diameter.

Furthermore, in the lens actuator of the present invention, with respect to the lens position, the magnetic repulsive force acting by the field coil and the magnet, and the magnetic force acting between the yoke and the magnet provided with the field coil inside the U-shaped cross section. Therefore, the lens position can be easily controlled.

According to the invention described in claim 2, by using the inner wall of the housing as a guide, there is no need to separately provide a guide portion inside the housing, the number of parts can be reduced, and a guide is provided inside the housing. Compared to the case, it is possible to increase the inner diameter of the inner yoke, and it is possible to reduce the diameter while maintaining the lens diameter.

In the lens actuator represented by the cited document 2 described above, it is necessary to provide a lens support portion and a guide portion inside the housing of the component, and there is a problem that the radial dimension becomes large.

To solve this problem, in the present invention, the inner wall of the housing is used as a guide, and the lens position is fixed only by magnetic attraction and repulsion, thereby suppressing the radial dimension without changing the lens diameter. It is possible.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a side sectional view of a lens actuator used in this embodiment, and FIG. 2 is an exploded perspective view of the lens actuator used in this embodiment.

With respect to FIG. 2, the magnet 4, the second yoke 6, the field coil 7, and the first yoke 3 are originally ring-shaped, but are shown with a part cut away in order to show a cross-sectional shape.

As shown in FIGS. 1 and 2, the lens actuator of the present embodiment has the lens 5 on the inner periphery of the ring-shaped second yoke 6 with the U-shaped cross-sectional opening facing the outer peripheral side in the radial direction. A movable part composed of the lens 5, the second yoke 6 and the field coil 7 is formed by a structure in which the outer diameter is fixed and the field coil 7 is arranged inside the U-shaped cross section of the second yoke 6. Yes.

Further, in addition to the movable portion, a ring-shaped first yoke 3 having a U-shaped cross section provided in the vicinity of the outer periphery of the movable portion and having a U-shaped cross section is concentric with the movable portion. The ring-shaped magnet 4 magnetized in the optical axis direction of the lens 5 is provided inside the U-shaped cross section of the first yoke 3.

With the above-described configuration, the lens actuator in the present embodiment has a magnetic flux generated by the field coil 7 at the U-shaped end portion of the second yoke 6 when a current is applied to the field coil 7. Concentrate.

Similar to the second yoke 6, the magnetic flux of the magnet 4 provided on the inner side also concentrates on the U-shaped end portion of the first yoke 6, so that the repulsive force of the magnetic flux concentrated on both U-shaped end portions causes The movable portion can be efficiently driven in the optical axis direction of the lens 5.

By using such a driving mechanism, the lens actuator shown in this embodiment reduces the outer diameter of the entire lens actuator without reducing the outer diameter of the lens 5 when the entire diameter is reduced. Making it possible.

When no current is applied to the field coil 7, the U-shaped end portion of the second yoke made of a magnetic material is also made of the same magnetic material and the magnet 4 is provided inside the U-shaped cross section. Since the second yoke 6 with the lens 5 fixed to the inner periphery is held by the magnetic attraction acting between the U-shaped end portions of the yoke, the second yoke 6 is separately held by a suspension or the like. This eliminates the need to reduce the number of parts and facilitates assembly.

In addition, when driving the movable part, in the lens actuator of this embodiment, the direction of the current applied to the field coil 7 is driven by an input in one direction repelling the field coil. The lens position is determined by the balance between the magnetic flux generated by the coil 7 and the magnetic attractive force generated between the U-shaped ends of the second yoke and the first yoke generated by the magnet 4. Can do.

Further, as shown in FIG. 3, in this embodiment, the outer wall of the movable portion is driven in the direction of the optical axis of the lens 5 while sliding on the inner wall of the upper housing 1 using the inner wall of the protrusion of the upper housing 1 as a guide. It has become.

For this reason, it is not necessary to separately provide a protrusion for providing a guide in the outer diameter direction of the lens 5, and the outer diameter dimension of the lens 5 can be set large.

As described above, by using the lens actuator shown in this embodiment, it is possible to obtain a lens actuator that has a simple structure and high magnetic efficiency and can be made thin.

Side sectional view of a lens actuator used in an embodiment of the present invention 1 is an exploded perspective view of a lens actuator used in an embodiment of the present invention. Operation explanatory diagram of a lens actuator used in an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper housing 2 Lower housing 3 1st yoke 4 Magnet 5 Lens 6 2nd yoke 7 Field coil
r Radial direction (radial direction of lens 5)

Claims (2)

Comprising first and second yokes formed in a ring shape having a U-shaped cross section made of a magnetic material;
The first yoke is formed on the radially inner periphery side of the ring shape with an opening having a U-shaped cross section,
The second yoke is formed on the radially outer peripheral side of the ring shape, with an opening having a U-shaped cross section,
A lens is fixed to the inner periphery of the second yoke;
The U-shaped end portions of each of the two yokes are arranged so that the openings of the two yokes face each other,
Further, a magnet magnetized in the optical axis direction of the lens is disposed inside one of the U-shaped cross sections of the two yokes,
A field coil wound around the optical axis direction of a lens fixed to the second yoke is disposed inside the U-shaped cross section of the other yoke, respectively. Lens actuator to do.
Regarding the housing for housing the first and second yokes, magnets, field coils, and lenses,
In the movable range when the lens is driven in the optical axis direction of the second yoke having the lens fixed to the inner periphery,
The lens actuator according to claim 1, wherein at least a part of the inner wall of the housing is formed so as to be in contact with an outer periphery of the second yoke.