JP4994342B2 - Lens drive device - Google Patents

Description

  The present invention relates to a lens driving device used for a camera such as a camera-equipped mobile phone. More specifically, the present invention relates to a technique for driving and holding a lens in the optical axis direction.

  In a camera device mounted on a camera-equipped mobile phone or the like, the lens is driven between two points: a position for normal shooting and a position slightly closer to the subject by a fixed distance than for normal shooting during close-up shooting. ing. However, such a device cannot be equipped with a lens driving device equipped with a motor in terms of size. For this reason, a camera-equipped mobile phone or the like is equipped with a lens driving device that directly magnetically drives the lens.

Here, as a magnetic drive type lens drive device, conventionally, it has a cylindrical case holding a lens, a ring-shaped drive magnet attached to the outer periphery of the case, and a drive coil facing the drive magnet, There is a configuration in which the case holding the lens is magnetically driven in the optical axis direction by controlling energization to the drive coil, and the case is magnetically held there (see, for example, Patent Document 1).
JP 2000-187862 A (page 2-3, FIG. 1-3)

  In a type in which a moving body such as a case for holding a lens is magnetically driven in the direction of the optical axis and is magnetically held there, there is a type that includes a spring member that supports the moving body so as to be movable in the direction of the optical axis. is there. However, it has not been proposed how to apply the biasing force of the spring member to the moving body.

  In view of the above problems, an object of the present invention is to propose a lens driving device that can use the urging force of a spring member that supports a moving body so as to be movable in the optical axis direction for driving and holding the position of the moving body. is there.

In order to solve the above-described problems, the present invention includes a moving body provided with a lens, and a fixed body that holds the moving body so as to be movable in the optical axis direction of the lens, and includes a drive magnet and a drive coil. In the lens driving device configured to move the moving body between a first lens holding position and a second lens holding position in the optical axis direction of the lens by a magnetic driving force, the moving body includes the driving The fixed body includes a spring member that supports the movable body so as to be movable in the optical axis direction, and first and second magnetic pieces disposed at positions separated in the optical axis direction. The spring member applies an urging force so that the movable body always moves from the first lens holding position to the second lens holding position , and the urging force of the spring member is the mobile first Lens and from the holding position is utilized to hold at the second lens holding position of movement and the moving body to the second lens holding position, said first magnetic piece, the optical axis of the drive magnet The second magnetic piece is disposed on the side of the second lens holding position in the optical axis direction of the drive magnet. The lens is a lens of a camera, the first lens holding position is a position for performing close-up shooting, and the second lens holding position is for normal shooting. When the lens is held at the first lens holding position, energization of the drive coil is stopped and the magnetic attraction force between the drive magnet and the first magnetic piece is used. ,in front When holding the lens in the second lens holding position, characterized in that to stop the energization of the drive coils utilizing magnetic attraction force between the second magnetic piece and the driving magnet.

According to the present invention can utilize biasing force of the spring member, the movement of the lens from the first lens holding position to the second lens holding position, and to hold the lens in the second lens holding position.

  In the present invention, the lens is preferably a camera lens of a camera-equipped mobile phone.

In the present invention, when the moving body is moved from the first lens holding position to the second lens holding position by the magnetic driving force, the moving body is moved by the fixed body at the second lens holding position. The impact is absorbed , and when the movable body is moved from the second lens holding position to the first lens holding position by the magnetic driving force, the first lens holding position is It is preferable that the moving body is adapted to absorb an impact by the fixed body .

  A lens driving device to which the present invention is applied will be described with reference to the drawings.

[overall structure]
1A, 1B, and 1C are longitudinal sectional views schematically showing a state in which a lens is held at a first lens holding position in a lens driving device to which the present invention is applied. The longitudinal cross-sectional view which shows typically the state in the middle of moving to the 2nd lens holding position from 1 lens holding position, and the longitudinal cross-sectional view which shows the state which hold | maintained the lens in the 2nd lens holding position It is. FIG. 2 is an enlarged perspective view showing a main part of the lens driving device shown in FIG.

  As shown in FIGS. 1A, 1B, 1C, and 2, the lens driving device 1 is for driving the lens 2 in a thin camera mounted on a camera-equipped mobile phone or the like. The lens moving body 3 including the lens 2 and the moving body 3 are moved between the first lens holding position P1 and the second lens holding position P2 in the optical axis direction F (focusing direction) of the lens 2. Each of these two lens holding positions P1 and P2 includes a fixed body 4 for holding the moving body 3 and a case 5 in which the moving body 3 and the fixed body 4 are housed. In the case 5, an opening is formed on the subject side (above the drawing) and an optical path is secured toward the inside of the apparatus (below the drawing).

  The lens moving body 3 includes a lens 2 and a ring-shaped drive magnet 6 attached to the outer periphery of the lens 2. The drive magnet 6 is attached with an annular back yoke 7 sandwiched between the lens 2 and the back yoke 7 also serves as a lens barrel of the lens 2.

  The fixed body 4 is a cylindrical member that surrounds the outer periphery of the drive magnet 6 and a spring member (not shown) such as a leaf spring or a coil spring that elastically supports the lens moving body 3 so as to be movable in the optical axis direction F of the lens 2. Drive is performed on each side of the drive coil 8, the stator yoke 11 having a U-shaped cross section or a C-shaped cross section so as to surround the drive coil 8, and the first and second lens holding positions P1 and P2. First and second washers 9 and 10 are arranged so as to face each of the end faces 61 and 62 of the magnet 6. Each of the first and second washers 9 and 10 is a ring-shaped magnetic piece made of a ferromagnetic material. Each of the surfaces facing the end surfaces 61 and 62 of the drive magnet 6 is made of a nonmagnetic elastic material. The spacer members 12 and 13 are attached.

Here, the dimension of each part is, for example,
Driving magnet 6
Outer diameter 3.7mm, inner diameter 3.1mm, height 1.6mm
Back yoke 7
Outer diameter 3.1mm, inner diameter 2.9mm, height 1.6mm
Drive coil 8
Outer diameter 4.5mm, inner diameter 4.1mm, height 1.4mm
Washers 9, 10
Outer diameter 3.9mm, inner diameter 3.1mm, height 0.25mm
Stator yoke 11
Outer diameter 4.7mm, inner diameter 3.9mm, height 1.6mm, plate thickness 1.6mm
Spacer members 12, 13
Outer diameter 3.9mm, inner diameter 3.1mm, height 0.1mm
Is set to

  In this embodiment, a neodymium plastic magnet is used as the drive magnet 6 and its bHc is 448 kA / m or more. On the other hand, the drive coil 8 is configured to generate a thrust of 100 mN or more.

[Lens drive operation]
In the lens driving device 1 configured as described above, driving performed on the lens 2 is as follows.

  First, in the state shown in FIG. 1A, the lens 2 (moving body 3) is at the first lens holding position P1, and in this state, the energization to the drive coil 8 is stopped. However, since the drive magnet 6 and the first washer 9 are magnetically attracted via the spacer member 12, the moving body 3 is held at the first lens holding position P1. Therefore, close-up photography can be performed with a camera-equipped mobile phone.

  When the lens 2 (moving body 3) is moved to the second lens holding position P2 from this state, the drive coil 8 is energized. As a result, as shown in FIG. 1 (B), the driving magnet 6 is pulled away from the first washer 9 by the magnetic force generated by the driving coil 8 and the driving magnet 6, and the moving body 3 is shown in FIG. ), The lens is moved to the second lens holding position P2. As a result, the drive magnet 6 and the second washer 10 are magnetically attracted via the spacer member 13. At this time, since the drive magnet 6 abuts against the spacer member 13, the impact is absorbed.

  Here, in a state where the drive magnet 6 and the second washer 10 are magnetically attracted via the spacer member 13, even if the energization to the drive coil 8 is stopped, the moving body 3 remains in the second lens holding position P2. Will be held. Therefore, it is possible to perform normal shooting with a camera-equipped mobile phone.

  Note that the operation of moving the lens 2 (moving body 3) from the second lens holding position P2 to the first lens holding position P1 is the same as the above-described operation, and thus the description thereof is omitted.

  As described above, in this embodiment, when the lens 2 is moved between the first lens holding position P1 and the second lens holding position P2, the driving coil 8 is energized to magnetically drive the moving body 3. When the lens 2 is held at the first lens holding position P1 and the second lens holding position P2, energization to the drive coil 8 is stopped and the magnetic attractive force between the drive magnet 6 and the magnetic pieces 9, 10 is used. To do. Therefore, while the lens 2 is held at the first lens holding position P1 or the second lens holding position P2, it is not necessary to energize the drive coil 8, so that power consumption can be kept low.

  Here, although not shown, the fixed body 4 includes a spring member that supports the movable body 3 so as to be movable in the optical axis direction F. Therefore, the urging force of the spring member is applied to the movable body 3 (lens). It can be used for driving and position holding in 2).

That is, when the urging force of the spring member always acts to move the moving body 3 from the first lens holding position P1 to the second lens holding position P2, the urging force of the spring member is applied to the first lens. It can be used to move the lens 2 from the holding position P1 to the second lens holding position P2, and to hold the lens 2 at the second lens holding position P2 .

(Effects of this embodiment)
As described above, in the lens driving device according to the present invention, when the moving body including the lens is moved between the first lens holding position and the second lens holding position, the driving coil is energized. However, when the lens is held at the first lens holding position, the energization to the drive coil is stopped and the magnetic attractive force between the drive magnet and the first magnetic piece is used. Therefore, while the lens is held at the first lens holding position, it is not necessary to energize the drive coil, so that power consumption can be kept low. Also, when the lens is held at the second lens holding position, it is possible to stop the energization of the drive coil and use the magnetic attractive force between the drive magnet and the second magnetic piece. Therefore, it is not necessary to energize the drive coil while the lens is held at the second lens holding position, so that power consumption can be kept low.

(A), (B), and (C) are longitudinal sectional views schematically showing a state in which the lens is held at the first lens holding position in the lens driving device to which the present invention is applied. FIG. 6 is a longitudinal sectional view schematically showing a state in the middle of moving from the lens holding position to the second lens holding position, and a longitudinal sectional view schematically showing a state in which the lens is held at the second lens holding position. . It is a perspective view which expands and shows the principal part of the lens drive device shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Lens 3 Moving body 4 Fixed body 5 Case 6 Drive magnet 7 Back yoke 8 Drive coil 9, 10 Washer 11 Stator yoke 12, 13 Spacer member

Claims (3)

A movable body having a lens, and a fixed body that holds the movable body in the direction of the optical axis of the lens. The movable body is driven by a magnetic driving force of a drive magnet and a drive coil. In the lens driving device configured to move between the first lens holding position and the second lens holding position in the axial direction,
The moving body includes the drive magnet,
The fixed body includes a spring member that supports the movable body so as to be movable in the optical axis direction, and first and second magnetic pieces disposed at positions separated in the optical axis direction ,
The spring member applies an urging force so that the movable body always moves from the first lens holding position to the second lens holding position .
Biasing force of the spring member is available from the first lens holding position of the movable body to the holding in the second lens holding position of movement and the moving body to the second lens holding position ,
The first magnetic piece is disposed so as to face an end surface of the drive magnet on the first lens holding position side in the optical axis direction,
The second magnetic piece is disposed so as to face an end surface of the drive magnet on the second lens holding position side in the optical axis direction,
The lens is a lens of a camera;
The first lens holding position is a position for performing close-up photography,
The second lens holding position is a position where normal shooting is performed,
When holding the lens at the first lens holding position, the energization to the drive coil is stopped and the magnetic attraction force between the drive magnet and the first magnetic piece is used, and the second When the lens is held at a lens holding position, the lens driving device is characterized in that energization of the drive coil is stopped and the magnetic attractive force between the drive magnet and the second magnetic piece is used. In claim 1,
The lens driving device according to claim 1, wherein the lens is a lens of a camera phone. In claim 1 or 2,
When the moving body is moved from the first lens holding position to the second lens holding position by the magnetic driving force, the moving body is absorbed by the fixed body at the second lens holding position. When the moving body is moved from the second lens holding position to the first lens holding position by the magnetic driving force, the moving body is moved to the first lens holding position. A lens driving device characterized in that an impact is absorbed by the fixed body.

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