Patent ID: 8246258

Claim:
A mechanical shutter, comprising: a base with a through hole defined therein; a blade arranged on the base; a shape memory alloy element comprising a first end attached to the base, and an opposite second end attached to the blade; and a control unit configured for controlling the shape memory alloy element to selectively deform into a pre-trained straight shape where the shape memory alloy element moves the blade to cover the through hole by heating the shape memory alloy element above a predetermined temperature, or into a coil spring shape where the shape memory alloy element moves the blade away from the through hole thus exposing the through hole when the temperature of the shape memory alloy is below the predetermined temperature; wherein the shape memory alloy element comprises two shape memory alloy units, the two shape memory alloy units are arranged symmetrically opposite to each other across an imaginary axis, which passes through a center of the through hole, and the two shape memory alloy units are in the pre-trained straight shape at the same time when moving the blade to cover the through hole and in the coil spring shape at the same time when moving the blade away from the through hole.