Actuator, and lens unit and camera with the same

• US 20060072913A1
• Filed: 10/03/2005
• Published: 04/06/2006
• Est. Priority Date: 10/01/2004
• Status: Active Grant

• Current Assignee: Tamron Company Limited
• Original Assignee: Tamron Company Limited
• Inventors: Noji, Takayoshi
• Granted Patent: US 7,620,305 B2
• Time in Patent Office: Days
• US Class Current: 396/55
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/687 by shifting the lens or sensor position

Abstract

The invention is directed to provide an actuator featuring a quick response with a simplified architecture, and a lens unit and a camera having the same.

An actuator (10) comprises a fixed member (12), a movable member (14), a movable member supporting means supporting the movable member so as to permit the movable member to move to an arbitrary position in a plane in parallel with the fixed member, at least three actuating coils (20) attached to either one of the fixed member and the movable member, actuating magnets (22) attached to the remaining one of the fixed member and the movable member in positions corresponding to the actuating coils so as to apply magnetic force to the corresponding actuating coils to affect each other when current flows in the actuating coils, a position sensing means (24) detecting a relative position of the movable member to the fixed member, and a control means (36) producing a coil position command signal on the basis of a command signal to instruct where the movable member is to be moved and controlling the drive current to flow in each of the actuating coils in response to the coil position command signal and the position data detected by the position sensing means.

Claims

1. An actuator comprising:

a fixed member;

a movable member;

a movable member supporting means for supporting the movable member so as to permit the movable member to move to an arbitrary position in a plane in parallel with the fixed member;

at least three actuating coils attached to either one of the fixed member and the movable member;

actuating magnets attached to the remaining one of the fixed member and the movable member in positions corresponding to the actuating coils so as to apply magnetic force to the corresponding actuating coils to affect each other when current flows in the actuating coils;

a position sensing means for detecting a relative position of the movable member to the fixed member; and

a control means for producing a coil position command signal on the basis of a command signal to instruct the position where the movable member is to be moved, and for controlling the drive current to flow in each of the actuating coils in response to the coil position command signal and the position data detected by the position sensing means.

2. The actuator according to claim 1, wherein the position sensing means is a magnetic sensor that detects a variation in magnetism, and it resides in position corresponding to each of the actuating magnets so as to detect the varied position of each actuating magnet.

3. The actuator according to claim 2, wherein the magnetic sensor is located inside each of the actuating coils.

4. The actuator according to claim 1, wherein the movable member supporting means is comprised of three spherical members interposed between the opposing faces of the fixed member and the movable member.

5. The actuator according to claim 1, wherein the actuating magnets are positioned on a predetermined circle, and at least one of the actuating magnets is arranged so that its magnetic neutral axis approximately directed in a radial direction of the circle.

6. The actuator according to claim 1, wherein there are three of the actuating coils, and these three actuating coils are disposed on a predetermined circle, each of the actuating coils being angularly away from each other by a central angle ranging from 90 degrees to 180 degrees.

7. The actuator according to claim 1, wherein there are three of the actuating coils, namely, first, second and third actuating coils, and these three actuating coils are disposed on a circle centered at a predetermined point so that they are angularly separated from each other at central angles of 90 degrees between the first and second actuating coils, (90+α

) degrees between the second and third actuating coils, and (180−

α

) degrees between the third and first actuating coils where 0≦

α

≦

90 is satisfied.

8. The actuator according to claim 6, wherein the actuating magnets arranged on the predetermined circle in positions corresponding to the actuating coils, so that magnetic neutral axes of the actuating magnets are approximately directed to radial direction of the circle, and the control means, upon receiving the command signal to rotate the movable member, produces the coil position command signal of the same level to the actuating coils so as to permit the movable member to rotate about the center of the circle on which the actuating magnets are disposed.

9. The actuator according to claim 7, wherein the actuating magnets are disposed on a predetermined circle in positions corresponding to the first, second and third actuating coils, so that magnetic neutral axes of the actuating magnets are approximately directed to radial direction of the circle, and the control means, upon receiving the command signal to translate the movable member, produces a coil position command signal r_X related to the first actuating coil, a coil position command signal r_Y related to the second actuating coil, and a coil position command signal r_v=r_x cos α

−

r_y sin α

related to the third actuating coil to induce an only translation motion of the movable member.

10. An actuator comprising:

a fixed member;

a movable member;

a movable member supporting means for supporting the movable member so as to permit the movable member to move to an arbitrary position in a plane in parallel with the fixed member; and

a drive means for translating and rotating the movable member relative to the fixed member.

11. A lens unit comprising:

a lens barrel;

a photographing lens housed in the lens barrel;

a fixed member secured to the lens barrel;

a movable member carrying an image stabilizing lens;

a movable member supporting means for supporting the movable member so as to permit the movable member to move to an arbitrary position in a plane in parallel with the fixed member;

at least three actuating coils attached to either one of the fixed member and the movable member;

actuating magnets attached to the remaining one of the fixed member and the movable member in positions corresponding to the actuating coils for applying magnetic force to the corresponding actuating coils to affect each other when current flows in the actuating coils;

a position sensing means for detecting a relative position of the movable member to the fixed member;

a vibration sensing means for detecting vibrations of the lens barrel;

a lens position command signal generating means for generating a lens position command signal to instruct where the image stabilizing lens is to be moved on the basis of a detection signal from the vibration sensing means; and

a control means for producing a coil position command signal related to the actuating coils on the basis of the lens position command signal from the lens position command signal generating means, and for controlling drive current to flow in the actuating coils in response to the coil position command signal and the position data detected by the position sensing means.

13. A camera having a lens unit defined in claim 11.

12. A lens unit comprising:

a lens barrel;

a photographing lens housed in the lens barrel;

a fixed member attached to the lens barrel;

a movable member carrying an image stabilizing lens;

a movable member supporting means for supporting the movable member so as to permit the movable member to move to an arbitrary position in a plane in parallel with the fixed member; and

a drive means for translating and rotating the movable member relative to the fixed member in the plane in parallel with the fixed member.