POSITION DETECTION APPARATUS

• US 20150015729A1
• Filed: 05/31/2013
• Published: 01/15/2015
• Est. Priority Date: 06/07/2012
• Status: Active Grant

• Current Assignee: Asahi Kasei Microdevices Corporation (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Microdevices Corporation (Asahi Kasei Corporation)
• Inventors: Kasamatsu, Arata
• Granted Patent: US 9,407,799 B2
• Time in Patent Office: Days
• US Class Current: 348/208.11
• CPC Class Codes: G02B 27/646 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 Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• CPC Class Codes: G03B 2205/0007 Movement of one or more optical elements for control of motion blur
• CPC Class Codes: G03B 2205/0053 Driving means for the movement of one or more optical element
• CPC Class Codes: G03B 2217/005 Blur detection
• CPC Class Codes: G03B 3/10 Power-operated focusing
• CPC Class Codes: G03B 5/00 Adjustment of optical system relative to image or object surface other than for focusing
• 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
• CPC Class Codes: H04N 23/57 Mechanical or electrical details of cameras or camera modules specially adapted for being embedded in other devices
• CPC Class Codes: H04N 23/67 Focus control based on electronic image sensor signals
• CPC Class Codes: H04N 23/6812 based on additional sensors, e.g. acceleration sensors
• CPC Class Codes: H04N 23/687 by shifting the lens or sensor position

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.

Claims

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;

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 2, further comprising:

a driver configured to hold the lens;

a support that is a terminal for supplying an electric current and/or a terminal for inputting or outputting a signal; and

a plurality of elastic members configured to be connected to the driver and each of a plurality of the supports that is the terminal,

wherein the plurality of the elastic members are connected to the first position sensor, the second position sensor, and at least one of the autofocus coil or the optical image stabilization coil.

9. The position detection apparatus according to claim 8, wherein the elastic member includes a conductive member.

10. The position detection apparatus according to claim 8, wherein the elastic member is configured to be a letter S-shaped spring or an annular plate spring.

11. 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.

12. The position detection apparatus according to claim 11, wherein the first position sensor and/or the second position sensor are arranged in any one of four corners inside the camera module.

13. The position detection apparatus according to claim 11, 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.

14. The position detection apparatus according to claim 13, 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.

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

16. The position detection apparatus according to claim 15, 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.

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

18. The position detection apparatus according to claim 17, 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.

19. The position detection apparatus according to claim 17, 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.

20. The position detection apparatus according to claim 19, wherein the predetermined angle is 45 degrees.

21. 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.

22. The position detection apparatus according to claim 21, 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.

23. The position detection apparatus according to claim 21, wherein the driver includes a first driver and a second driver, the first driver being a lens barrel.

24. The position detection apparatus according to claim 23, wherein the first driver is fitted into the second driver.

25. The position detection apparatus according to claim 21,

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.

26. The position detection apparatus according to claim 25, wherein the plurality of projections and the plurality of the shafts are provided at three or more locations to provide supports at three or more points.

27. The position detection apparatus according to claim 21, wherein the driver includes a first driver and a second driver, the first driver being a lens barrel, and

wherein the plurality of projections are provided in the lens barrel that is the first driver.

28. The position detection apparatus according to claim 27, wherein the magnet is secured to the first driver.

29. The position detection apparatus according to claim 27, wherein the magnet is fitted into a cutout portion of the second driver.