Patent ID: 6893263

Claim:
A single dot tactile reading module comprising: a frame supporting a tactile dot having a top portion movable in a direction parallel to an axis of the frame so that the top portion appears above a top of the frame in an up position of the tactile dot, and disappears below the top of the frame in a lower position of the tactile dot, means connecting said dot elastically with a cam which can rotate around an axis held by said frame in such a way that rotation of said cam in one direction produces an upward motion of said dot, and rotation of said cam in an opposite direction produces a downward motion of said dot, means for locking said dot elastically in two stable positions, either up or down, if no rotating torque is applied to said cam or if the rotating torque value is below a given reference value, means for rotating said cam comprising one shape memory wire implemented so that a contraction of the wire by electrical Joule heating generates a rotation of said cam which reverses the tactile dot position, moving it down if it is initially up and vice-versa, means for sending through said wire an electrical current pulse which produces in said wire by Joule effect enough heat to bring the wire above a phase transition temperature to make said wire contract, means for cooling said wire rapidly at an end of a contraction cycle to bring the wire back to an initial cold state, means for helping said wire recover an initial length and for bringing said wire in a position symmetrical from a previous initial position with respect to a plane containing the axis of said dot and the rotation axis of said cam, during the cooling phase so the helping means do not produce a rotation of said cam during the cooling phase, and means, located at a bottom of said frame, for electrically connecting both ends of said wire to a common printed circuit board in an easily removable manner.