SHAPE MEMORY ALLOY ACTUATION APPARATUS

A miniature camera lens actuation apparatus employs an SMA actuator comprising SMA wire to move a camera lens element. To provide autofocus, the SMA actuator is heated across its range of contraction and the resistance at which the focus is at an acceptable level is stored. To combat hysteresis, the...

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Bibliographische Detailangaben
Hauptverfasser:	TOPLISS, RICHARD, HOOLEY, ANTHONY
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	ACCESSORIES THEREFOR APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USINGWAVES OTHER THAN OPTICAL WAVES APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FORPROJECTING OR VIEWING THEM BLASTING CINEMATOGRAPHY ELECTRIC COMMUNICATION TECHNIQUE ELECTRICITY ELECTROGRAPHY HEATING HOLOGRAPHY LIGHTING MACHINES OR ENGINES FOR LIQUIDS MECHANICAL ENGINEERING MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOTOTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISEPROVIDED FOR OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS OPTICS OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR PHOTOGRAPHY PHYSICS PICTORIAL COMMUNICATION, e.g. TELEVISION PRODUCING MECHANICAL POWER SPRING, WEIGHT, INERTIA OR LIKE MOTORS WEAPONS WIND, SPRING WEIGHT AND MISCELLANEOUS MOTORS
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Beschreibung
Zusammenfassung:	A miniature camera lens actuation apparatus employs an SMA actuator comprising SMA wire to move a camera lens element. To provide autofocus, the SMA actuator is heated across its range of contraction and the resistance at which the focus is at an acceptable level is stored. To combat hysteresis, there is performed a flyback in which the SMA actuator is cooled, before heating the SMA actuator to the stored resistance. The stored resistance is adjusted to combat creep caused by non-linear heating of the SMA actuator. The SMA wire has conductive material extending along on a portion of the SMA wire which extends from a member connected to the SMA wire and being in electrical connection with the SMA wire in order to short out that portion of the SMA wire to reduce creep. Additional material is applied over the SMA wire and the member to reduce fatigue.