Lens driving device, camera module, and camera mounting device

Patent metadata

Field	Value
Publication number	US-9915802-B2
Application number	US-201515319848-A
Country	US
Kind code	B2
Filing date	Jun 18, 2015
Priority date	Jul 11, 2014
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

Provided is a technology which: has a structure that is advantageous for size reduction and power saving; and, moreover, is useful when automatic focusing using a closed-loop control system. A lens driving device comprising: an autofocus driving unit; a Hall element which separates an autofocus magnet section in the optical axis direction and is disposed in a position corresponding to one opposing corner section of the autofocus magnet section and in a manner such that the detection direction matches the optical axis direction; a first position detection magnet which is disposed near the Hall element and in a manner such that the magnetisation direction matches the optical axis direction; and a second position detection magnet which has the same configuration as the first position detection magnet and is disposed in a point symmetrical position relating to the first position detection magnet and the optical axis direction.

First claim

The invention claimed is:

1. A lens driving device comprising:
an auto-focusing driving part,
a Hall device,
a first position detection magnet, and
a second position detection magnet,
the auto-focusing driving part including:
an auto-focusing coil part disposed at a periphery of a lens part; and
an auto-focusing magnet part composed of four permanent magnets and disposed separately from the auto-focusing coil part in a radial direction, the four permanent magnets being magnetized in a short direction and disposed in a square frame shape;

the auto-focusing driving part being configured to perform automatic focusing by moving an auto focus movable part including the auto-focusing coil part in a light axis direction with respect to an auto focus fixing part including the auto-focusing magnet part by utilizing a driving force of a voice coil motor composed of the auto-focusing coil part and the auto-focusing magnet part;
the Hall device being disposed separately from the auto-focusing magnet part in the light axis direction at a positon corresponding to one diagonal part of the auto-focusing magnet part such that a detection direction coincides with the light axis direction;
the first position detection magnet being disposed in proximity to the Hall device such that a magnetization direction coincides with the light axis direction;
the second position detection magnet having a configuration similar to that of the first position detection magnet, and being disposed at a position point symmetrical with the first position detection magnet about the light axis direction.

2. The lens driving device according to claim 1 , wherein each of the four permanent magnets includes a yoke part at an end surface in proximity to the first position detection magnet or the second position detection magnet in a longitudinal direction.

3. The lens driving device according to claim 2 , wherein the yoke parts adjacent to each other are coupled with each other.

4. The lens driving device according to claim 2 , wherein:
parts of the first position detection magnet and the auto-focusing magnet part which are close to each other have the same polarity; and
parts of the second position detection magnet and the auto-focusing magnet part which are close to each other have the same polarity.

5. The lens driving device according to claim 4 further comprising an elastic supporting part configured to elastically support the auto focus movable part with respect to the auto focus fixing part, wherein:
the first position detection magnet and the second position detection magnet are disposed such that the first position detection magnet and the second position detection magnet have no acting force in a movement direction with respect to the auto focus movable part at a reference position of the auto focus movable part, and that an acting force in a movement direction is generated in a direction opposite to a direction of a restoration force of the elastic supporting part when the auto focus movable part is moved.

6. The lens driving device according to claim 1 , wherein:
the auto focus movable part includes a lens holder, the lens holder including:
a coil winding part for disposing the auto-focusing coil part; and
a tying part for tying both ends of the auto-focusing coil part; and

the tying part is formed to protrude outward in a radial direction, and has a tapered shape whose diameter is reduced toward an inner side in the radial direction.

7. The lens driving device according to claim 1 further comprising a shake-correcting driving part,
the shake-correcting driving part including:
a shake-correcting magnet part disposed at an auto focus unit including the auto focus movable part and the auto focus fixing part; and
a shake-correcting coil part disposed separately from the shake-correcting magnet part in the light axis direction;

the shake-correcting driving part being configured to perform shake correction by swinging a shake-correcting movable part including the shake-correcting magnet part in a plane orthogonal to the light axis direction with respect to a shake-correcting fixing part including the shake-correcting coil part by utilizing a driving force of a voice coil motor composed of the shake-correcting coil part and the shake-correcting magnet part.

8. The lens driving device according to claim 7 , wherein the auto-focusing magnet part serves also as the shake-correcting magnet.

9. The lens driving device according to claim 7 further comprising a supporting member configured to support the shake-correcting movable part with respect to the shake-correcting fixing part in the light axis direction with a space between the shake-correcting movable part and the shake-correcting fixing part, wherein the supporting member includes:
two coil feeding suspension wires serving as power feeding paths to the auto-focusing coil part;
two Hall device feeding suspension wires serving as power feeding paths to the Hall device; and
two signal suspension wires serving as signal paths to the Hall device.

10. The lens driving device according to claim 1 further comprising a temperature detection part for detecting a temperature of a region around the Hall device.

11. The lens driving device according to claim 10 , wherein the temperature detection part includes a resistance circuit, and detects the temperature based on a resistance value of the resistance circuit.

12. The lens driving device according to claim 10 , wherein the temperature detection part is provided on a substrate on which the Hall device is disposed.

13. The lens driving device according to claim 10 , wherein the temperature detection part detects the temperature based on a resistance value of the Hall device.

14. A camera module comprising:
the lens driving device according to claim 1 ;
a lens part mounted to the auto focus movable part; and
an image capturing part configured to capture a subject image imaged by the lens part.

15. A camera mounting device comprising:
the camera module according to claim 14 ;
the camera mounting device being an information device or a transport device.

Assignees

• Murakami Tomoyuki
• Hayashi Ichiro
• Kudo Shota
• Mitsumi Electric Co Ltd

Inventors

• Murakami Tomoyuki
• Hayashi Ichiro
• Kudo Shota

Classifications

• G02B7/04

  with mechanism for focusing or varying magnification · CPC title

• G03B5/00

  Adjustment of optical system relative to image or object surface other than for focusing · CPC title

• G02B27/646

  compensating for small deviations, e.g. due to vibration or shake (movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68) · CPC title

• H04M1/0264

  for a camera module assembly · CPC title

• G02B7/102

  controlled by a microcomputer (cameras with interchangeable lenses G03B17/14) · CPC title