OPTICAL IMAGE STABILISATION COMPRISING SHAPE MEMORY ALLOY ACTUATORS

• US 20110249131A1
• Filed: 09/11/2009
• Published: 10/13/2011
• Est. Priority Date: 09/12/2008
• Status: Active Grant

• Current Assignee: Cambridge Mechatronics Limited
• Original Assignee: Cambridge Mechatronics Limited
• Inventors: Topliss, Richard, Leedham, Robert John
• Granted Patent: US 8,848,064 B2
• Time in Patent Office: Days
• US Class Current: 348/208.7
• 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: G03B 2205/0007 Movement of one or more optical elements for control of motion blur imaging systems in general using optical elements for stabilisation of the position of the image G02B27/64
• CPC Class Codes: G03B 2205/0076 using shape memory alloys
• CPC Class Codes: G03B 5/00 Adjustment of optical system relative to image or object surface other than for focusing
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations

Abstract

A camera apparatus capable of providing optical image stabilisation comprises: a support structure; a camera unit comprising an image sensor and a lens system; a suspension system comprising a plurality of flexure elements supporting the camera unit on the support structure in a manner allowing the camera unit to tilt; and a plurality of SMA actuators each formed as SMA wire connected between the camera unit and the support structure and arranged on contraction to drive tilting of the camera unit. The SMA wire may be fixed to the camera unit at its ends and hooked over an element of the support structure. A vibration sensor, whose output is used as the basis for generating drive signals, may be mounted on the camera unit.

Claims

1. A camera apparatus comprising:

a support structure;

a camera unit comprising an image sensor and a lens system for focussing an image on the image sensor;

a suspension system supporting the camera unit on the support structure in a manner allowing the camera unit to tilt around two notional axes that are perpendicular to each other and to the optical axis of the lens system with freedom to move along the optical axis; and

at least three SMA actuators each connected between the camera unit and the support structure and arranged, on contraction, to drive displacement of the camera unit along the optical axis relative to the support structure, the SMA actuators being arranged at different positions around the optical axis so that the SMA actuators, on contraction to drive differential displacement, drive tilting of the camera unit.

2. An apparatus according to claim 1, wherein the suspension system comprises a plurality of flexure elements supporting the camera unit on the support structure in a manner allowing the camera unit to tilt around two notional axes that are perpendicular to each other and to the optical axis of the lens system on deflection of the flexure elements.

3. An apparatus according to claim 2, wherein the resultant deflection of the flexure elements, on contraction of the SMA actuators, provides the sole biassing force reacting against the SMA actuator.

4. An apparatus according to claim 3, further comprising a biassing element, separate from the suspension system, that provides a biassing force reacting against the SMA actuator on contraction of the SMA actuator.

5. An apparatus according to claim 1, wherein each SMA actuator comprises a piece of SMA wire extending between the camera unit and the support structure perpendicular to a notional line radial of the optical axis.

7. An apparatus according to claim 1, wherein the SMA actuators are arranged at different positions spaced evenly around the optical axis.

8. An apparatus according to claim 7 comprising four SMA actuators.

36. A camera apparatus according to claim 1, further comprising:

a vibration sensor mounted on the camera unit and arranged to generate output signals representative of the vibration of the camera unit; and

a control circuit connected to the SMA actuators for supplying drive signals thereto, the control circuit being arranged to generate the drive signals in response to the output signals of the vibration sensor.

37. An apparatus according to claim 36, wherein the control circuit has an adjustable gain and is arranged to adjust its gain to minimize the sensed vibrations.

38. An apparatus according to claim 37, wherein the vibration sensor is arrange to generate output signals representative of the angulr velocity of the camera unit.

39. An apparatus according to claim 38, wherein the vibration sensor is a gyroscope sensor.

40. An apparatus according to claim 38, wherein the control circuit is arranged to derive control signals representing the demanded angle of tilt of the camera unit on the basis of the output signals of the vibration sensor, to detect the resistances of the SMA actuators and to generate the drive signals in accordance with the demanded angle of tilt represented by the control signals using the detected resistances of the SMA actuators as feedback signals.

6. (canceled)

9. A camera apparatus comprising:

a support structure;

a camera unit comprising an image sensor and a lens system for focussing an image on the image sensor;

a suspension system comprising a plurality of flexure elements supporting the camera unit on the support structure in a manner allowing the camera unit to tilt around two notional axes that are perpendicular to each other and to the optical axis of the lens system on deflection of the flexure elements; and

a plurality of SMA actuators each connected between the camera unit and the support structure and arranged on contraction to drive tilting of the camera unit.

10. A camera apparatus according to claim 9, wherein the SMA actuators each comprise a piece of SMA wire fixed at both ends to one of the camera unit and the support structure and intermediate its ends hooked over a portion of a respective flexure element that is connected to the other one of the camera unit and the support structure, the SMA actuators being arranged on contraction to drive tilting of the camera unit, the resultant deflection of the flexure elements providing a biassing force reacting against the SMA actuator.

17. An apparatus according to claim 9, wherein said resultant deflection of the flexure elements provides the sole biassing force reacting against the SMA actuator.

19. An apparatus according to claim 10, wherein said one of the camera unit and the support structure is the support structure and said other one of the camera unit and the support structure is the camera unit.

20. A camera apparatus according to claim 9, further comprising a biassing element, separate from the suspension system, that provides a biassing force reacting against the SMA actuator on contraction of the SMA actuator.

22. An apparatus according to claim 20, wherein the SMA actuators are arranged at different positions spaced evenly around the optical axis.

23. An apparatus according to claim 22 comprising four SMA actuators.

11-16. -16. (canceled)

18. (canceled)

21. (canceled)

24-30. -30. (canceled)

31. A camera apparatus comprising:

a support structure;

a camera unit comprising an image sensor and a lens system for focussing an image on the image sensor;

a suspension system supporting the camera unit on the support structure in a manner allowing the camera unit to tilt around two notional axes that are perpendicular to each other and to the optical axis of the lens system;

an actuator arrangement arranged to drive tilting of the camera unit;

a vibration sensor mounted on the camera unit and arranged to generate output signals representative of the vibration of the camera unit; and

a control circuit connected to the actuator arrangement for supplying drive signals thereto, the control circuit being arranged to generate the drive signals in response to the output signal of the vibration sensor.

32. An apparatus according to claim 31, wherein the control circuit has an adjustable gain and is arranged to adjust its gain to minimise the sensed vibrations.

33. An apparatus according to claim 31, wherein the vibration sensor is arranged to generate output signals representative of the angular velocity of the camera unit.

34. An apparatus according to claim 33, wherein the vibration sensor is a gyroscope sensor.

35. An apparatus according to claim 31, wherein the actuator arrangement comprises a plurality of SMA actuators each arranged on contraction to drive tilting of the camera unit.