Lens drive device and electromagnetic drive unit

• US 10,379,321 B2
• Filed: 02/08/2018
• Issued: 08/13/2019
• Est. Priority Date: 02/09/2017
• Status: Active Grant

• Current Assignee: Tdk Taiwan Corp. (TDK Corporation)
• Original Assignee: TDK Corporation
• Inventors: Ichihashi, Shusuke
• Primary Examiner(s): Ben, Loha
• Application Number:
  US15/891,503
• Publication Number:
  US 20180224631A1
• Time in Patent Office: 551 Days
• Field of Search: 359811, 359814, 359823, 359824, 359554, 359557, 359694-696, 310 1204, 310 1216, 310 1222, 310 1224
• CPC Class Codes: G02B 13/001 Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras G02B23/243 takes precedence
• CPC Class Codes: G02B 7/02 for lenses supports for magnifying lenses G02B25/002
• CPC Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• CPC Class Codes: G03B 3/10 Power-operated focusing
• CPC Class Codes: H01H 47/22 for supplying energising current for relay coil
• CPC Class Codes: H02K 41/03 Synchronous motors; Motors moving step by step; Reluctance motors H02K41/035 takes precedence
• CPC Class Codes: H04N 23/54 Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof

Abstract

A lens drive device includes a movable portion, a fixed portion, and a nonmagnetic case. The movable portion includes a double-pole magnet having two pairs of magnetic poles, a first coil opposing to the double-pole magnet in a perpendicular direction to a light axis, and a lens holder being movable to the double-pole magnet in a direction of the light axis. The fixed portion includes a second coil arranged so as to oppose to the double-pole magnet in the direction of the light axis. The nonmagnetic case is attached to the fixed portion so as to cover the movable portion. The double-pole magnet includes a first section and a second section. L1/L2 is 0.9 to 1.1, where L1 and L2 are respectively a length of the first and second sections in the direction of the light axis.

Claims

1. A lens drive device comprising:

a movable portion including a double-pole magnet having two pairs of magnetic poles, a first coil opposing to the double-pole magnet in a perpendicular direction to a light axis, and a lens holder holding the first coil and a lens and being movable to the double-pole magnet in a direction of the light axis;

a fixed portion including a second coil arranged so as to oppose to the double-pole magnet in the direction of the light axis;

a support portion configured to support the movable portion so that the movable portion is movable relatively to the fixed portion in the perpendicular direction to the light axis; and

a nonmagnetic case provided with a through hole where light enters into the lens and attached to the fixed portion so as to cover the movable portion,

wherein the double-pole magnet includes a first section having a first magnetization direction and opposing to the first coil and a second section having a second magnetization direction different from the first magnetization direction and opposing to the second coil, and

L1/L2 is 0.9 to 1.1, where L1 is a length of the first section in the direction of the light axis, and L2 is a length of the second section in the direction of the light axis.

2. The lens drive device according to claim 1, wherein the movable portion includes a yoke arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet.

3. The lens drive device according to claim 2, wherein:

the yoke covers the whole of a first outer side surface in the first section of the outer side surface and covers a part of a second outer side surface in the second section of the outer side surface, and

a distance between the yoke and the fixed portion is larger than a distance between the double-pole magnet and the fixed portion.

4. The lens drive device according to claim 2, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

the movable portion has at least two yokes arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to two double-pole magnets arranged vertically to each other among the four double-pole magnets.

5. The lens drive device according to claim 2, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

the movable portion has at least two yokes arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to two double-pole magnets arranged in parallel to each other among the four double-pole magnets.

6. The lens drive device according to claim 2, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

at least one of the four double-pole magnets is different from another double-pole magnet arranged in parallel to the double-pole magnet with respect to thickness in the perpendicular direction to the light axis.

7. The lens drive device according to claim 6, wherein

the movable portion has a yoke arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to the double-pole magnet where the thickness is relatively small.

8. The lens drive device according to claim 3, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

the movable portion has at least two yokes arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to two double-pole magnets arranged vertically to each other among the four double-pole magnets.

9. The lens drive device according to claim 3, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

the movable portion has at least two yokes arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to two double-pole magnets arranged in parallel to each other among the four double-pole magnets.

10. The lens drive device according to claim 3, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

at least one of the four double-pole magnets is different from another double-pole magnet arranged in parallel to the double-pole magnet with respect to thickness in the perpendicular direction to the light axis.

11. The lens drive device according to claim 10, wherein

the movable portion has a yoke arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to the double-pole magnet where the thickness is relatively small.

12. The lens drive device according to claim 1, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

the movable portion has at least two yokes arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to two double-pole magnets arranged vertically to each other among the four double-pole magnets.

13. The lens drive device according to claim 1, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

the movable portion has at least two yokes arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to two double-pole magnets arranged in parallel to each other among the four double-pole magnets.

14. The lens drive device according to claim 1, wherein:

the movable portion has four double-pole magnets respectively arranged along a side of a rectangle surrounding the lens holder, and

at least one of the four double-pole magnets is different from another double-pole magnet arranged in parallel to the double-pole magnet with respect to thickness in the perpendicular direction to the light axis.

15. The lens drive device according to claim 14, wherein

the movable portion has a yoke arranged on an outer side surface opposite to an inner side surface facing the first coil among side surfaces of the double-pole magnet and arranged correspondingly to the double-pole magnet where the thickness is relatively small.

16. An electromagnetic drive unit comprising:

the lens drive device according to claim 1; and

an electromagnetic drive device arranged with a predetermined distance to the lens drive device and including an external coil and an external magnet configured to move relatively by electromagnetic drive force,

wherein a magnetic force received by the external coil from the double-pole magnet is smaller than a magnetic force received by the external coil from the external magnet.

17. The electromagnetic drive unit according to claim 16, wherein:

the electromagnetic drive device includes an external lens configured to be driven separately from the lens of the lens drive device by electromagnetic drive force of the external coil and the external magnet, and

the lens drive device and the electromagnetic drive device constitute a dual lens drive device.