KR20100040659A - Driving device and lens driving device - Google Patents

Abstract

PURPOSE: A drive unit and lens driving apparatus fit the length direction both ends of the main part magnet part to a pair of part magnet parts. The deterioration of the magnetic force can be prevented under the high temperature environment. CONSTITUTION: It is composed of magnetic field generating element consisting of the voice coil motor is the yoke and magnet(182) and driving coil. The one-way of the driving coil and magnetic field generating element is attached to the fixing unit. Another side of the driving coil and magnetic field generating element is attached to the moving element. As long as it fits the main part magnet part and main part magnet part from both ends and it is installed, magnet is composed of the part magnet part of the pair.

Description

DRIVING DEVICE AND LENS DRIVING DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device using a voice coil motor (VCM) as a drive unit, and more particularly to an autofocus lens drive device used in a portable compact camera.

As is known, a voice coil motor (VCM) is used as a drive part of a drive device for linearly driving a movable part (driven part) with respect to a fixed part. The voice coil motor is composed of a magnetic field generating portion (magnetic field generating means) consisting of a yoke and a magnet, and a drive coil. One of the magnetic field generating portion (magnetic field generating means) and the driving coil is attached to the fixed portion, and the other is attached to the movable portion. The drive device may be, for example, a lens drive device as described later.

In the lens driving apparatus, the lens assembly is held by the lens holder. The voice coil motor is energized by the drive coil, thereby acting as an actuator capable of positioning the lens holder in the optical axis direction by the interaction between the magnetic field of the permanent magnet and the magnetic field caused by the current flowing through the drive coil.

On the other hand, a portable small camera is mounted in the mobile phone with a camera. In this portable compact camera, an autofocus lens driving device is used. In such an autofocus lens driving apparatus, a lens is used as a movable portion (driven portion). Conventionally, various autofocus lens driving apparatuses have been proposed.

For example, Patent Document 1 (Japanese Patent Laid-Open No. 2005-128392) discloses a lens drive device excellent in impact resistance. The lens driving device disclosed in Patent Document 1 includes a substantially cylindrical yoke, a base on which the yoke is mounted, a lens support (lens holder) disposed on the inner circumferential side of the yoke, and a pair of plates attached to the lens support. With a spring. The pair of leaf springs is also called the front spring and the rear spring. The front spring is disposed on the optical axis direction front side (one side) of the lens in the lens support, and the rear spring is disposed on the optical axis direction rear side (the other side) of the lens. The yoke has a substantially c-shaped cross section, a magnet (permanent magnet) is disposed inside the c-shape, and a drive coil is disposed on the inner circumferential side of the magnet within the c-shape. The magnet is fixed to the base via the rear spacer. The drive coil is fixed to the outer peripheral portion of the lens support. The outer periphery of the lens support is inside the yoke. As a result, the outer peripheral portion of the lens support moves the c-shaped gap of the yoke. The yoke is fixed to the inner circumferential side of the base. The outer peripheral end of the rear spring is fixed to the base of the base between the rear spacers.

In the lens driving apparatus disclosed in Patent Document 1, the lens support is substantially cylindrical in shape and a lens (lens assembly, barrel) is housed therein. The lens support is attached to move the inner circumferential side of the yoke along the optical axis. The front side spring consists of a substantially annular leaf spring, and has an inner peripheral side end and an outer peripheral side end. The inner circumferential side end portion of the front spring is clamped and fixed between the lens support and the cap. A front spacer is interposed between the outer peripheral end of the front spring and the yoke. The rear spring is substantially the same shape as the front spring and consists of a substantially annular leaf spring. The inner peripheral end of the rear spring is fixed to the rear end of the lens support. The outer circumferential end of the rear spring is fixed between the base of the base and the rear spacer.

In the lens driving apparatus disclosed in Patent Document 1, the driving coil has a cylindrical shape, and the magnet also has a cylindrical shape. In detail, the magnet is composed of four magnet pieces each having an arc shape, and has a cylindrical shape as a whole. In addition, in patent document 1, the specific material (structure) of a magnet is not described at all.

In addition, Patent Document 2 (Japanese Patent Laid-Open No. 2006-293243) can smoothly drive a lens even when the photographing direction is used inclined with respect to the vertical direction, and can accurately orient the lens optical axis direction to the photographing direction. A lens driving device is disclosed. The lens driving device disclosed in Patent Document 2 includes a holder (lens holder) for holding a lens, an annular drive coil attached to the holder, and a magnetic field provided on the fixed part side and applying a radial driving magnetic field to the coil. A first spring member (front spring) for connecting the upper side of the holder and the upper side of the fixing member, and a second spring member for connecting the lower side of the holder and the lower side of the fixing member Rear spring). Here, the inner circumferential side end portion of the front spring is sandwiched and fixed to the front end of the lens holder and the cap in the same manner as in Patent Document 1.

In this patent document 2, the magnetic field generating means comprises a combination of a cylindrical magnet (magnet) provided on the outer circumferential side of the annular drive coil and a U-shaped cylindrical yoke made of a magnetic material such as soft iron. Also in this patent document 2, the specific material (structure) of a cylindrical magnet (magnet) is not described at all.

In addition, Patent Document 3 (Japanese Patent Laid-Open No. 2006-258969) discloses a mobile phone with a camera that shortens the time required for autofocus. The mobile phone with a camera (lens drive device) disclosed in this patent document 3 has a holder (lens holder) having a cylindrical portion with a lens attached to one end thereof, a drive coil fixed to the holder around the cylindrical portion of the holder; And a yoke having a permanent magnet facing the driving coil, and a pair of leaf springs provided on both sides of the optical axis direction of the cylindrical portion of the holder so as to be displaceable in the optical axis direction while the holder is positioned in the radial direction. Equipped. By energizing the drive coil, the lens can be positioned in the optical axis direction by the interaction between the magnetic field of the permanent magnet and the magnetic field caused by the current flowing through the drive coil. One of the pair of leaf springs is called an upper leaf spring (front spring), and the other of the pair of leaf springs is called a lower leaf spring (rear spring). The inner circumferential side end portion of the upper leaf spring (front spring) is sandwiched between the upper end (front end) of the holder and the stopper and fitted to the holder.

In Patent Document 3, the drive coil has a cylindrical shape, and a plurality of permanent magnets (magnets) are disposed so as to face the inner circumferential surface of the outer cylinder portion of the yoke at intervals from the coil. Each of the plurality of permanent magnets (magnets) has an arc shape. Also in this patent document 3, the specific material (structure) of each permanent magnet (magnet) is not described at all.

In addition, Patent Document 4 (Japanese Patent Laid-Open No. 2006-50694) discloses a lens driving apparatus using an approximately flat plate-shaped magnet as a permanent magnet (magnet) because an arc-shaped magnet is expensive. In this patent document 4, the example which uses a neodymium magnet as a permanent magnet (magnet) is described. Moreover, in patent document 4 (and said patent document 3), the magnetic flux leakage prevention means which prevents a magnetic flux from leaking below a permanent magnet is provided. In Patent Literature 4, as the magnetic flux leakage preventing means, a magnetic member is disposed so as to connect a plurality of permanent magnets in contact with the lower end surface (surface opposite to the connecting portion of the circular yoke) of the permanent magnet. In patent document 4, the magnetic member is formed from the magnetic material which consists of iron, nickel, cobalt, and those alloys, and the example which uses a cold rolled sheet steel is disclosed.

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-128392 (FIGS. 1 and 2)

Patent Document 2: Japanese Patent Application Laid-Open No. 2006-293243 (Fig. 1)

Patent Document 3: Japanese Patent Laid-Open No. 2006-258969 (Fig. 2, Fig. 3)

Patent document 4: Unexamined-Japanese-Patent No. 2006-50694 (FIG. 15, FIG. 16)

In the lens driving apparatus disclosed in the above-mentioned patent documents 1 to 3, as a magnet used for the voice coil motor, the specific material thereof is not disclosed at all. Therefore, in patent documents 1-3, it is thought that what consists of one type of material is used as a magnet of a voice coil motor.

On the other hand, the autofocus actuator disclosed in Patent Document 4 discloses an example in which a neodymium magnet (neodymium magnet) is used as a permanent magnet (magnet).

As described above, as a magnet of a voice coil motor, for example, a neodymium magnet (for example, Nd-Fe-B) made of one type of material having a large magnetic flux density is used.

However, the neodymium magnets have a problem that their magnetic force is reduced due to the surrounding heat (under high temperature) (a thermal potato is produced). That is, in the conventional voice coil motor, due to heat in a high temperature environment, self-heating at the time of driving the voice coil motor, etc., a magnetothermal magnetism of the magnet is generated, and its magnetic characteristics are deteriorated. As a result, in the lens focusing apparatus for autofocus using such a conventional voice coil motor as an actuator, there exists a problem that thrust of the lens will be disturbed under high temperature environment.

In addition, the magnetic flux leakage preventing means disclosed in Patent Document 4 is for preventing magnetic flux leakage of the magnet, and cannot suppress the thermal potato of the magnet itself.

An object of the present invention is to provide a drive device and a lens drive device that can prevent deterioration of thrust even in a high temperature environment.

Other objects of the present invention will become clear as the description proceeds.

According to the first aspect of the present invention, there is provided a voice coil motor as a drive device (10; 10A) having a fixed portion (12), a movable portion (14), and a voice coil motor for linearly driving the movable portion with respect to the fixed portion. The magnetic field generator comprising the yoke 20 and the magnets 18 and 182, and the driving coil 16, one of the magnetic field generating portion and the driving coil is attached to the fixed portion, the magnetic field generating portion and the driving coil The other side of the drive unit is attached to the movable portion, the magnet 182 is composed of a main magnet portion 182M and a pair of secondary magnet portions 182S; 182S 'provided by inserting the main magnet portions at both ends thereof. , The primary magnet portion 182M has a first magnetic flux density and a first Curie point, and each of the pair of secondary magnet portions 182S; 182S 'has a second magnetic flux density smaller than the first magnetic flux density, and a first Curie. The drive device which has a 2nd Curie point higher than a point is obtained.

In the drive device 10 (10A) according to the first aspect of the present invention, the pair of secondary magnet portions 182S may be provided at both ends in the longitudinal direction of the primary magnet portion 182M, for example, The pair of secondary magnet portions 182S 'may be provided at both ends in the thickness direction of the primary magnet portion 182M, for example. The main magnet portion 182M is made of, for example, a neodymium magnet, and each of the pair of secondary magnet portions 182S and 182S 'is, for example, an alnico magnet, a samarium cobalt magnet, and a ferrite. It may be selected from the group of magnets.

According to the second aspect of the present invention, there is provided a lens holder (14) having a cylindrical portion (140) for holding a lens assembly, a drive coil (16) fixed to be positioned around the cylindrical portion to the lens holder, The yoke 20 having the permanent magnet 18 facing the driving coil and the optical shaft O are provided on both sides of the optical axis O in the cylindrical portion of the lens holder, and the optical axis O is positioned in the radial direction. And a pair of leaf springs 22 and 24 for displaceably supporting in the direction, each of the pair of leaf springs having inner circumferential side ends 222 and 242 attached to the lens holder 14 and the yoke 20. The lens holder has an outer circumferential side end portion 224 attached thereto, and is energized by the driving coil 16, by interaction between the magnetic field of the permanent magnet 18 and the magnetic field caused by the current flowing through the driving coil 16. In the lens driving apparatus 10 (10A) which can position 14 in the optical axis O direction, the driving coil 16 is M (M is 4). The even-numbered rectangular tube shape is described above, and the permanent magnet 18 is composed of M rectangular permanent magnet pieces 182 and 182A, and each of the M permanent magnet pieces is a main magnet portion 182M. And a pair of secondary magnet portions 182S; 182S 'provided by sandwiching the primary magnet portion at both ends thereof, and the primary magnet portion 182M has a first magnetic flux density and a first Curie point, Each of the secondary magnet sections 182S and 182S 'has a second magnetic flux density smaller than the first magnetic flux density and a second Curie point higher than the first Curie point.

In the lens drive device 10 (10A) according to the second aspect of the present invention, M may be the same as, for example. The pair of secondary magnet portions 182S may be provided at both ends in the longitudinal direction of the main magnet portion 182M, for example. In this case, the pair of leaf springs may be fixed to the pair of secondary magnet portions at both ends in the longitudinal direction of the primary magnet portion. Instead, the pair of secondary magnet portions 182S 'may be provided at both ends in the thickness direction of the primary magnet portion 182M, for example. The main magnet portion 182M is made of, for example, a neodymium magnet, and each of the pair of secondary magnet portions 182S and 182S 'is, for example, an alnico magnet, a samarium cobalt magnet, and a ferrite. It may be selected from the group of magnets.

In addition, the code | symbol in the said parentheses is attached for easy understanding, and is only an example, Of course, it is not limited to these.

In the present invention, each of the M permanent magnet pieces (magnets) includes a main magnet portion and a pair of secondary magnet portions provided by sandwiching the main magnet portion at both ends thereof, and the main magnet portion includes a first magnetic flux density and a first Curie point. Each of the pair of secondary magnet portions has a second magnetic flux density smaller than the first magnetic flux density and a second Curie point higher than the first Curie point, so that deterioration of thrust can be prevented even in a high temperature environment.

(The best mode for carrying out the invention)

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

With reference to FIGS. 1-3, the lens drive apparatus 10 by 1st Embodiment of this invention is demonstrated. 1 is an external perspective view of the lens driving apparatus 10, FIG. 2 is a cross-sectional view of the lens driving apparatus 10, and FIG. 3 is an exploded perspective view of the lens driving apparatus 10. Here, as shown in FIGS. 1-3, the rectangular coordinate system (X, Y, Z) is used. 1 to 3, in the Cartesian coordinate system (X, Y, Z), the X axis is the front-rear direction (depth direction), the Y axis is the left-right direction (width direction), and the Z axis is the vertical direction (height direction) )to be. In addition, in the example shown to FIGS. 1-3, the up-down direction Z is the optical axis O direction of a lens.

In the actual use situation, however, the optical axis O direction, that is, the Z axis direction becomes the front-rear direction. In other words, the upper direction of the Z axis becomes the front direction, and the lower direction of the Z axis becomes the rear direction.

The illustrated lens driving device 10 is provided in a mobile phone with a camera that can be autofocused. The lens drive device 10 is for moving the lens assembly (barrel) (not shown) in the optical axis O direction. The lens drive device 10 has an actuator base 12 disposed below (rear) the Z axis direction (optical axis O direction). Although not shown, an imaging device arranged on a substrate is mounted on the lower portion (back) of the actuator base 12. This imaging device picks up the subject image formed by the lens assembly and converts it into an electrical signal. The imaging element is configured by, for example, a charge coupled device (CCD) type image sensor, a complementary metal oxide semiconductor (CMOS) type image sensor, or the like. Therefore, the camera module is comprised by the combination of the lens drive apparatus 10, a board | substrate, and an imaging element.

The lens drive device 10 includes a lens holder 14 having a cylindrical portion 140 for holding a lens assembly (barrel), and a lens holder 14 positioned around the cylindrical portion 140 in the lens holder 14. Yoke 20 having a fixed drive coil 16, a permanent magnet (magnet) 18 facing the drive coil 16, and an optical axis of the cylindrical portion 140 of the lens holder 14 A pair of leaf springs 22 and 24 provided on both sides in the O) direction are provided.

Here, the actuator base 12 acts as a fixed part, the lens holder 14 acts as a movable part (driven part), the drive coil 16, the permanent magnet (magnet) 18, and the yoke 20 ) Acts as a voice coil motor. Then, the combination of the yoke 20 and the permanent magnet (magnet) 18 acts as a magnetic field generating portion (magnetic field generating means).

The pair of leaf springs 22 and 24 support the lens holder 14 so as to be displaceable in the optical axis O direction in the state where the lens holder 14 is positioned in the radial direction. Of the pair of leaf springs 22 and 24, one leaf spring 22 is called an upper leaf spring, and the other leaf spring 24 is called a lower leaf spring.

As described above, in the actual use situation, the upper direction in the Z axis direction (optical axis O direction) is the front direction, and the lower direction in the Z axis direction (optical axis O direction) is the rear direction. Therefore, the upper leaf spring 22 is also called the front spring, and the lower leaf spring 24 is also called the rear spring.

As shown in FIG. 3, the yoke 20 has an octagonal cylinder shape. That is, the yoke 20 has an octagonal outer cylinder portion 202 and an octagonal ring-shaped end portion 204 provided at the upper end (front end) of the outer cylinder portion 202.

As shown in FIG. 2, the outer cylinder portion 202 of the yoke 20 has four long sides 202-1 facing each other and four stages disposed between these four long sides 202-1. It consists of side sides 202-2. Therefore, the drive coil 16 also has the shape of an octagonal cylinder in conformity with the shape of the octagonal yoke 20. That is, the drive coil 16 is composed of four long sides 161 and four short sides 162 disposed between the four long sides. The cylindrical portion 140 of the lens holder 14 has four contact surfaces 140-1 protruding radially outward at an angular interval of 90 °. Four long sides 161 of the drive coil 16 are bonded to these four contact surfaces 140-1. That is, the drive coil 16 is bonded to four contact surfaces 140-1.

On the other hand, the permanent magnets (magnets) 18 include four long rectangular permanent magnets 182-1 facing the four long sides 161 of the drive coil 16, and four of the drive coils 16. It consists of four short rectangular permanent magnets 182-2 which oppose the short side part 162. As shown in FIG. Four long rectangular permanent magnets 182-1 are disposed on the inner walls of the four long sides 202-1 of the outer cylinder portion 202 of the yoke 20, and four short rectangular permanent magnets 182-2. Is disposed on the inner walls of the four short side edges 202-2 of the outer cylinder portion 202 of the yoke 20. In any case, the permanent magnet 18 is composed of eight rectangular permanent magnet pieces 182 arranged on each side of the octagonal cylindrical portion 202 of the yoke 20.

As shown in FIG. 2, the permanent magnet (magnet) 18 is arrange | positioned at the inner peripheral surface of the outer cylinder part 202 of the yoke 20 at intervals from the drive coil 16. As shown in FIG.

As described above, in the illustrated embodiment, since the driving coil 16 has an octagonal cylinder shape, and the permanent magnet (magnet) 18 is composed of eight rectangular permanent magnet pieces 182, it is permanent. The magnet 18 can be manufactured at low cost. As a result, there is an advantage that the lens driving device 10 also becomes inexpensive.

The front spring 22 is disposed on the front side in the optical axis O direction in the lens holder 14, and the rear spring 24 is disposed on the rear side in the optical axis O direction in the lens holder 14. The front side spring 22 and the rear side spring 24 have substantially the same structure. That is, the front spring 22 has an inner circumferential side end 222 attached to the lens holder 14 and an outer circumferential side end 224 attached to the yoke 20. Three arm portions 226 are provided between the inner circumferential side end portion 222 and the outer circumferential side end portion 224. Each arm 226 connects the inner circumferential side end portion 222 and the outer circumferential side end portion 224.

Similarly, the rear side spring 24 has an inner circumferential side end portion 242 attached to the lens holder 14 and an outer circumferential side end portion (not shown) attached to the yoke 20. Three arm portions 246 are provided between the inner circumferential side end portion 242 and the outer circumferential side end portion. Each arm 246 connects the inner circumferential side end portion 242 and the outer circumferential side end portion.

In addition, an inner peripheral side edge part is also called an inner ring, and an outer peripheral side edge part is also called an outer ring.

The inner circumferential side end portion 222 of the front side spring 22 is sandwiched and fixed to the lens holder 14 and the stopper 26. In other words, the stopper 26 fits the lens holder 14 so as to sandwich the inner circumferential side end portion 222 of the front spring 22 with the lens holder 14. On the other hand, the outer circumferential side end portion 224 of the front spring 22 is sandwiched and fixed between the yoke 20 and the cover 28.

The stopper 26 has a function as described below. That is, the stopper 26 has a function of closely contacting the inner circumferential side end portion 222 of the front side spring 22 to the lens holder 14 with high accuracy. Thereby, the dispersion | variation in the VCM (voice coil motor) characteristic can be improved. The stopper 26 also has a function of improving the adhesive strength of the front spring 22. This improves the impact resistance of the lens drive apparatus 10. In addition, the stopper 26 has a function of preventing deformation of the front spring 22 during the drop impact of the lens drive device 10. This also improves the impact resistance of the lens drive apparatus 10. The stopper 28 also has a function of determining the mechanical stroke of the lens drive apparatus 10.

In addition, as described later, in the present embodiment, the stopper 26 is also provided with an anti-rotation function of the lens holder 14.

On the other hand, the outer peripheral end of the rear spring 24 is fixed to the yoke 20 via the spacer 30. In other words, the outer peripheral side end portions of the spacer 30 and the rear spring 24 are sandwiched and fixed between the yoke 20 and the actuator base 12. The inner circumferential side end portion 242 of the rear spring 24 is fixed to the rear end side of the lens holder 14.

The female screw 142 is cut off on the inner circumferential wall of the cylindrical portion 140 of the lens holder 14. On the other hand, although not shown, the male screw screwed to the female screw 142 is cut on the outer circumferential wall of the lens assembly (barrel). Therefore, in order to mount the lens assembly (barrel) to the lens holder 14, the lens assembly (barrel) is rotated about the optical axis O with respect to the cylindrical portion 140 of the lens holder 14, thereby causing the optical axis O. By screwing along the direction, the lens assembly (barrel) is accommodated in the lens holder 14 and joined to each other by an adhesive or the like.

At this time, the lens holder 14 may rotate together, but as described later, the lens holder 14 is completely prevented from rotating.

By energizing the drive coil 16, the lens holder 14 (lens assembly) is moved in the optical axis O direction by the interaction between the magnetic field of the permanent magnet 18 and the magnetic field caused by the current flowing through the drive coil 16. It is possible to adjust the position.

The sheet-shaped electrode 32 is arrange | positioned between the rear side spring 24 and the actuator base 12. As shown in FIG. This sheet-shaped electrode 32 is for supplying electric power to the drive coil 16.

In the illustrated embodiment, the stopper 26 has two c-shaped anti-rotation presses 262 provided at two rotationally symmetric positions rotated by 180 ° with respect to the optical axis O. These U-shaped anti-rotation pressing portions 262 serve as anti-rotation members that completely prevent the lens holder 14 from rotating when the lens assembly is mounted on the cylindrical portion 140 of the lens holder 14. Works. That is, when the lens assembly 14 of the lens assembly 14 is mounted on the cylindrical portion 140, the jig (not shown) is inserted into and retained by the two U-shaped anti-rotation pressing portions 262 to thereby maintain the lens holder 14. ) Is completely prevented from rotating. At this time, the clearance between the stopper 16 and the cover 28 is secured (maintained).

4 is a perspective view showing the configuration of the permanent magnet piece 182. The permanent magnet piece 182 shown is comprised from the main magnet part 182M of rectangular shape, and a pair of sub magnet part 182S provided by sandwiching this main magnet part 182M from the both ends of the longitudinal direction. The main magnet portion 182M has a first magnetic flux density and a first Curie point (first Curie temperature). Each of the pair of secondary magnet portions 182S has a second magnetic flux density smaller than the first magnetic flux density and a second Curie point (second Curie temperature) higher than the first Curie point (first Curie temperature).

The main magnet portion 182M is also called a driving magnet portion for lens driving purposes. On the other hand, since each of the pair of secondary magnet portions 182S can be used to prevent thermal potatoes in the high temperature environment of the primary magnet portion 182M, it is also referred to as a magnet portion for preventing thermal potatoes.

5, magnetic properties (magnetic flux density (Br) [T], Curie point (Curie temperature) [° C.], and recommended use temperature [° C.]) of various magnets are shown. In Fig. 5, magnetic properties of ferrite magnets, samarium cobalt magnets (Sm-Co magnets), alnico magnets, and neodymium magnets (Nd-Fe-B) are shown.

It can be seen that, among the various magnets shown in FIG. 5, the magnetic flux density of the neodymium magnet (Nd-Fe-B) is the largest. Therefore, in the example of illustration, the neodymium-type magnet Nd-Fe-B is used as the main magnet part 182M. However, it can be seen that among the various magnets shown in FIG. 5, the Curie point (Curie temperature) of the neodymium magnets Nd-Fe-B is the lowest. Therefore, the neodymium-based magnet Nd-Fe-B is deteriorated in the magnetic domain direction due to its unstable state in the high temperature environment, and thus the magnetic force decreases (heated potatoes).

In order to prevent the thermal reduction of such a neodym type magnet (main magnet part 182M) in a high temperature environment, in the present embodiment, both ends of the main magnet part 182M in the longitudinal direction are connected to a pair of secondary magnet parts 182S. It is wearing. In the example of illustration, the magnet selected from the group of an alnico magnet, a samarium cobalt magnet, and a ferrite magnet is used as sub magnet part 182S. As is clear from FIG. 5, it can be seen that the alnico magnet, the samarium cobalt magnet, and the ferrite magnet all have a magnetic flux density smaller than that of the neodym magnet, and have a Curie point higher than the Curie point of the neodym magnet. have.

In this way, the main magnet part (driving magnet part) (182M) is inserted into a pair of part magnet parts (magnet part for thermal potato measures) 182S from both ends in the longitudinal direction, and thus, the main magnet part (driving magnet part). The magnetic domain direction of the sub-) 182M can be kept strong against the influence of heat.

As a result, it is possible to provide the permanent magnet piece 182 which does not deteriorate in magnetic properties even in a high temperature environment. Therefore, the lens driving apparatus 10 using such a permanent magnet piece 182 can prevent that thrust can be prevented. In addition, even in a high temperature environment, the deterioration of the magnetic force of the permanent magnet piece 182 does not occur, so that it is possible to manufacture a mobile phone with an autofocus compatible camera for reflow. In addition, even in a situation where a current flows in the drive coil 16 for a long time (such as when shooting a video for a long time), autofocus of the autofocus of a mobile phone with a camera can be performed.

With reference to FIG. 6, the lens drive apparatus 10A which concerns on 2nd Embodiment of this invention is demonstrated. 6 is a schematic cross-sectional view of the lens driving apparatus 10A. In the lens drive device 10A shown in the drawing, the pair of leaf springs 22 and 24 are connected to a pair of secondary magnet portions (heat-sensitive measures) at both ends in the longitudinal direction of the main magnet portion (driving magnet portion) 182M. Magnet part) (182S) for fixing.

That is, in the lens driving apparatus 10A shown in FIG. 6, the permanent magnet piece 182 is used also for the purpose of fixing the pair of leaf springs 22 and 24. FIG.

FIG. 7: is a front view which shows the modification 182A of the permanent magnet piece 182 shown in FIG. In the permanent magnet piece 182 shown in FIG. 4, although the main magnet part 182M is pinched by the pair of secondary magnet parts 182S from the both ends of the longitudinal direction, the permanent magnet piece 182 shown in FIG. ), The main magnet portion 182M is sandwiched by a pair of secondary magnet portions 182S 'from both ends in the thickness direction thereof.

In the permanent magnet piece 182A having such a configuration, similarly to the permanent magnet piece 182 shown in Fig. 4, the thermal potato can be prevented in the high temperature environment of the main magnet portion 182M.

As mentioned above, although this invention was demonstrated by the preferable embodiment, it is clear that various changes are possible for those skilled in the art within the range which does not deviate from the mind of this invention. For example, in the above embodiment, the driving coil 16 has an octagonal cylinder shape, and the permanent magnet 18 is composed of eight rectangular permanent magnet pieces 182. The M (M is an even number of 4 or more) square cylinder shape, the permanent magnet may be composed of M rectangular permanent magnet pieces.

1 is an external perspective view of a lens driving apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the lens driving device shown in FIG. 1.

3 is an exploded perspective view of the lens driving apparatus shown in FIG. 1.

4 is a perspective view illustrating a configuration of a permanent magnet piece.

5 is a diagram showing magnetic characteristics (magnetic flux density (Br) [T], Curie point (Curie temperature) [° C.], and recommended use temperature [° C.]) of various magnets.

6 is a schematic cross-sectional view of a lens driving apparatus according to a second embodiment of the present invention.

FIG. 7 is a front view showing a modification of the permanent magnet piece shown in FIG. 4. FIG.

(Explanation of the sign)

10 Lens Drive 12 Actuator Base (Fixed)

14 Lens holder (movable part) 140 cylindrical part

142 Female Thread 16 Coil

18 Permanent Magnet 182, 182A Permanent Magnet

182M main magnet part (driving magnet part)

182S part magnet part (magnet part for hot potato measures)

182S 'part magnet part (heat magnet measures magnet part)

20 yoke 22 front spring (upper leaf spring)

222 Inner peripheral end (inner ring) 224 Outer peripheral end (outer ring)

24 Rear side spring (lower leaf spring) 242 Inner peripheral end (inner ring)

26 stopper O optical axis

Claims (10)

A drive device comprising a fixed portion, a movable portion, and a voice coil motor for linearly driving the movable portion with respect to the fixed portion, wherein the voice coil motor comprises a magnetic field generating portion consisting of a yoke and a magnet, and a driving coil. In the driving device, one of the magnetic field generating portion and the drive coil is attached to the fixed portion, the other of the magnetic field generating portion and the drive coil is attached to the movable portion, The magnet is composed of a main magnet portion and a pair of secondary magnet portions provided by sandwiching the main magnet portion from both ends thereof, The main magnet portion has a first magnetic flux density and a first Curie point, Each of the pair of secondary magnet portions has a second magnetic flux density smaller than the first magnetic flux density and a second Curie point higher than the first Curie point. 2. The drive device according to claim 1, wherein the pair of secondary magnet portions are provided at both ends in the longitudinal direction of the primary magnet portion. The drive device according to claim 1, wherein the pair of secondary magnets are provided at both ends in the thickness direction of the primary magnet portion. The method of claim 1, wherein the main magnet portion is made of neodymium-based magnets, Wherein each of the pair of secondary magnet portions is selected from the group of alnico magnets, samarium cobalt magnets, and ferrite magnets. A lens holder having a cylindrical portion for holding a lens assembly, a drive coil fixed to the lens holder to be positioned around the cylindrical portion, a yoke having a permanent magnet facing the drive coil, A pair of leaf springs provided on both sides of the cylindrical portion in the optical axis direction, the pair of leaf springs supporting the lens holder so as to be displaceable in the optical axis direction in a state in which the lens holder is positioned in the radial direction, each of the pair of leaf springs The lens holder has an inner circumferential side end attached to the yoke and an outer circumferential side end attached to the yoke and is energized by the driving coil, thereby interacting with the magnetic field of the permanent magnet and the magnetic field caused by the current flowing through the driving coil. In the lens drive device which can be positioned in the optical axis direction, The drive coil has an M (M is an even number of 4 or more) cylindrical shape, the permanent magnet is composed of M rectangular permanent magnet pieces, Each of the M permanent magnet pieces is composed of a main magnet portion and a pair of secondary magnet portions provided by sandwiching the main magnet portion at both ends thereof. The main magnet portion has a first magnetic flux density and a first Curie point, Each of the pair of secondary magnet portions has a second magnetic flux density smaller than the first magnetic flux density and a second Curie point higher than the first Curie point. 6. A lens driving apparatus according to claim 5, wherein M is equal to eight. 6. The lens driving apparatus according to claim 5, wherein the pair of secondary magnet portions are provided at both ends in the longitudinal direction of the primary magnet portion. 8. The lens driving apparatus according to claim 7, wherein the pair of leaf springs are fixed by being inserted into the pair of secondary magnet portions at both ends in the longitudinal direction of the primary magnet portion. 6. The lens driving apparatus according to claim 5, wherein the pair of secondary magnets are provided at both ends in the thickness direction of the primary magnet portion. 10. The magnet according to any one of claims 5 to 9, wherein the main magnet portion is made of a neodymium magnet. And each of the pair of secondary magnet portions is selected from the group of alnico magnets, samarium cobalt magnets, and ferrite magnets.

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