ASSEMBLY METHOD FOR A SHAPE MEMORY ALLOY ACTUATOR ARRANGEMENT

• US 20180149142A1
• Filed: 05/26/2016
• Published: 05/31/2018
• Est. Priority Date: 05/26/2015
• Status: Active Grant

• Current Assignee: Cambridge Mechatronics Limited
• Original Assignee: Cambridge Mechatronics Limited
• Inventors: BUNTING, Stephen Matthew, HOWARTH, James, BROWN, Andrew Benjamin David
• Granted Patent: US 10,648,459 B2
• Time in Patent Office: Days
• CPC Class Codes: F03G 7/0614 using shape memory elements
• CPC Class Codes: F03G 7/065 using a shape memory element
• 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: G02B 7/09 adapted for automatic focusing or varying magnification
• CPC Class Codes: G03B 2205/0076 using shape memory alloys
• CPC Class Codes: G03B 3/10 Power-operated focusing
• CPC Class Codes: Y10T 29/49812 Temporary protective coating, impregnation, or cast layer

Abstract

An SMA actuator arrangement is assembled using a strut element shaped to comprise a sacrificial strut body and crimp tabs held apart by the sacrificial strut body. A SMA wire is laid across the crimp tabs which are folded and pressed to form crimps holding the SMA wire. The crimps are then attached to static and moving parts, after which the sacrificial strut body is removed. The method allows the crimping to be performed without hindrance from the static and moving parts, the sacrificial strut body holding the relative locations of the crimps prior to attachment.

Claims

1. A method of assembling a shape memory alloy actuator arrangement comprising a static part and a moving part, and at least one shape memory alloy wire extending therebetween, the method comprising:

providing a strut element shaped to comprise a sacrificial strut body and crimp tabs held apart by the sacrificial strut body;

laying at least one shape memory alloy wire across the crimp tabs of the strut element;

folding and pressing the crimp tabs over the shape memory alloy wire to form crimps holding the shape memory alloy wire therebetween;

attaching the crimps to the static part and the moving part, respectively; and

removing the sacrificial strut body, leaving the crimps attached to the static part and the moving part, respectively.

2. The method according to claim 1, wherein the strut element is a shaped fret and the crimp tabs are at the ends of the sacrificial strut body.

3. The method according to claim 1, wherein the crimps are attached to the static part and the moving part, respectively, by adhesive.

4. The method according to claim 1, wherein the crimps are attached to the static part and the moving part, respectively, by a mechanical locating feature.

5. The method according to claim 1, wherein the shape memory alloy actuator arrangement is a shape memory alloy actuator arrangement for a camera wherein the moving part comprises a camera lens assembly.

6. The method according to claim 1, wherein the at least one shape memory alloy wire comprises plural shape memory alloy wires.

7. The method according to claim 6, wherein the plural shape memory alloy wires include shape memory alloy wires that cross.

8. The method according to claim 1, wherein the sacrificial strut body is removed by mechanical or laser cutting.

9. The method according to claim 1, wherein

the strut element is shaped to further comprise two mount portions held apart by the sacrificial strut body, the crimp tabs being formed on the mount portions, and

the step of attaching the crimps to the static part and the moving part, respectively, comprises mounting the mount portions to the static part and the moving part, respectively.

10. The method according to claim 1, wherein

the strut element is shaped to comprise a series of attachment units each shaped to comprise a sacrificial strut body and crimp tabs held apart by the sacrificial strut body, and

said steps of folding and pressing the crimp tabs, attaching the crimps, and removing the sacrificial strut body are performed in parallel on successive attachment units of the strut element.

11. The method according to claim 10, further comprising cutting attachment units from a continuous strip in parallel with performing said steps of folding and pressing the crimp tabs, attaching the crimps, and removing the sacrificial strut body.