Patent ID: 6422012
Filing Date: 2002-07-23
Classification: F03G,G12B

Abstract:
A positioning device comprising:(i) an actuator constructed from a shape-memory effect alloy, said actuator having a pre-set memorised shape such that, from another shape, the actuator generates a first force when heated above a transition temperature; (ii) heat supply means connected to said actuator; (iii) urging means arranged to exert a second force acting a direction opposite to the first force; (iv) a positionable member moveable between first and second positions under the influence of said first and second forces; (v) sensing means comprising a Hall sensor and a magnet for detecting the position of the positionable member relative to a reference point; and (vi) control means operably connected with said heat supply means and said sensing means for controlling the temperature of the actuator; wherein, above an elevated temperature above the transition temperature, the positionable member is moved towards its first position against the action of the urging means, and wherein, below the elevated temperature, the positionable member is moved towards its second position by the urging means.