Position detection apparatus

Patent metadata

Field	Value
Publication number	US-9407799-B2
Application number	US-201314375892-A
Country	US
Kind code	B2
Filing date	May 31, 2013
Priority date	Jun 7, 2012
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

There is provided a position detection apparatus that includes an autofocus mechanism and an optical image stabilization mechanism by using a closed loop control, in which a magnet is commonly used as an autofocus magnet and an optical image stabilization magnet to achieve downsizing. The position detection apparatus includes the autofocus mechanism that moves a lens along an optical axis (Z axis) of the lens, and the optical image stabilization mechanism that moves the lens in a direction orthogonal to the optical axis. A permanent magnet is secured to the lens, and moves according to the movement of the lens. The amount of movement thereof is detected by position sensors. The permanent magnet for autofocus used in the autofocus mechanism and the permanent magnet for optical image stabilization used in the optical image stabilization mechanism is provided in the vicinity of the lens for common use.

First claim

The invention claimed is:

1. A position detection apparatus that detects a position of a lens on a plane orthogonal to an optical axis direction of the lens to detect a position for optical image stabilization, and detects a position of the lens in the optical axis direction to detect a position for autofocus, the position detection apparatus comprising:
a magnet configured to move as the lens moves in the optical axis direction and in an in-plane direction orthogonal to the optical axis, the magnet being made of a single body including an S pole and an N pole aligned in a direction parallel to the optical axis direction, and the S pole and the N pole aligned in a direction orthogonal to the optical axis direction;
a first position sensor for the autofocus configured to sense a magnetic field to be changed according to the movement of the magnet in the optical axis direction to detect the position of the lens in the optical axis direction; and
a second position sensor for the optical image stabilization configured to sense a magnetic field to be changed according to the movement of the magnet in the plane orthogonal to the optical axis direction to detect the position of the lens on the plane orthogonal to the optical axis direction.

2. The position detection apparatus according to claim 1 , further comprising:
an autofocus coil provided in a vicinity of the magnet and configured to move the lens in the optical axis direction; and
an optical image stabilization coil provided in the vicinity of the magnet and configured to move the lens in a direction orthogonal to the optical axis direction.

3. The position detection apparatus according to claim 1 ,
wherein the first position sensor is a first hall element, and the second position sensor is a second hall element,
wherein the first hall element is arranged so that a normal direction of a magnetic sensitivity surface of the first hall element is orthogonal to or parallel to the optical axis, and
wherein the second hall element is arranged so that a normal direction of a magnetic sensitivity surface of the second hall element is orthogonal to or parallel to the optical axis.

4. The position detection apparatus according to claim 1 , further comprising a yoke configured to form a magnetic path of a magnetic flux from the magnet.

5. The position detection apparatus according to claim 1 , further comprising:
an autofocus mechanism configured to control the position of the lens in the optical axis direction; and
an optical image stabilization mechanism configured to control the position of the lens in the plane orthogonal to the optical axis direction,
wherein the autofocus mechanism is configured to detect the position of the lens in the optical axis direction from an output of the first position sensor and is configured to feed back a detected result to a lens position controller that controls the position of the lens, so as to control the position of the lens in the optical axis direction, and
wherein the optical image stabilization mechanism is configured to detect the position of the lens on the plane orthogonal to the optical axis direction from an output of the second position sensor and is configured to feed back a detected result to the lens position controller that controls the position of the lens, so as to control the position of the lens on the plane orthogonal to the optical axis direction.

6. The position detection apparatus according to claim 5 , wherein the autofocus mechanism is configured to control the position of the lens based on the output of the second position sensor for the optical image stabilization.

7. The position detection apparatus according to claim 5 , wherein the optical image stabilization mechanism is configured to control the position of the lens based on the output of the first position sensor for the autofocus.

8. The position detection apparatus according to claim 1 , further comprising a camera module configured to accommodate the lens, the magnet, the first position sensor, and the second position sensor.

9. The position detection apparatus according to claim 8 , wherein the first position sensor and/or the second position sensor are arranged in any one of four corners inside the camera module.

10. The position detection apparatus according to claim 8 , further comprising a third position sensor for optical image stabilization configured to detect the position of the lens on the plane orthogonal to the optical axis direction, the third position sensor being different from the second position sensor,
wherein the second position sensor and/or the third position sensor are arranged in any one of four corners inside the camera module.

11. The position detection apparatus according to claim 10 , wherein the second position sensor is configured to detect the position of the lens in a first direction orthogonal to the optical axis, and the third position sensor detects the position of the lens in a second direction orthogonal to the optical axis and the first direction.

12. The position detection apparatus according to claim 11 , wherein the first direction is a direction different from a direction of a side of the camera module.

13. The position detection apparatus according to claim 12 , wherein the first direction is a direction that forms an angle of 45 degrees with respect to the direction of the side of the camera module.

14. The position detection apparatus according to claim 11 , wherein the second direction is a direction different from the direction of the side of the camera module.

15. The position detection apparatus according to claim 14 , wherein the second direction is a direction that forms an angle of 45 degrees with respect to the direction of the side of the camera module.

16. The position detection apparatus according to claim 14 , further comprising a lens position detector configured to detect the position of the lens based on an output of the second position sensor and an output of the third position sensor,
wherein when an A axis is the first direction and an X axis is an axis obtained by rotating the A axis by a predetermined angle centering around the optical axis, and when a B axis is the second direction and a Y axis is an axis obtained by rotating the B axis by the predetermined angle in a same direction as the A axis centering around the optical axis, the lens position detector is configured to detect the positions of the lens on the X axis and the Y axis.

17. The position detection apparatus according to claim 16 , wherein the predetermined angle is 45 degrees.

18. The position detection apparatus according to claim 1 , further comprising:
a driver configured to hold the lens and to include a plurality of through holes for a shaft to be fitted into; and
a plurality of the shafts respectively fitted into the plurality of through holes.

19. The position detection apparatus according to claim 18 , wherein the plurality of through holes and the plurality of the shafts are provided at three or more locations to provide supports at three or more points.

20. The position detection apparatus according to claim 18 ,
wherein the driver includes a plurality of projections that is integrally provided on an outer peripheral surface of the driver and that has the plurality of through holes, and
wherein the plurality of the shafts are respectively fitted into the plurality of through holes of the plurality of projections.

21. The position detection apparatus according to claim 20 , whe

Assignees

• Asahi Kasei Microdevices Corp

Inventors

• Kasamatsu Arata

Classifications

• G03B3/10 Primary

  Power-operated focusing · CPC title

• H04N23/55

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• H04N23/687 Primary

  by shifting the lens or sensor position · CPC title

• H04N23/57

  Mechanical or electrical details of cameras or camera modules specially adapted for being embedded in other devices · CPC title

• H04N23/54 Primary

  Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils · CPC title