A durable, shock-resistant electromagnetic optical scanner with polyimide-based hinges

Abstract

This paper presents a moving-coil electromagnetic optical scanner with newly developed hinge structure consisting of multilayered polyimide films with aluminum lead wires in between. The main purpose is to obtain a scanner with good durability and shock resistance for practical use. Polyimide has both features, and the aluminum lead wires, connecting the moving-coils and fixed electrode pads, are more reliable, because they are located inside the hinge, where the stress caused by torsional deformation and atmospheric degradation are minimal. An electromagnetic actuator is used to satisfy the following requirements; a millimeter-sized mirror, resonant and galvanometric operation, and scan angle control. Scanner prototypes with two different specifications (i.e., fast scanner and slow scanner) were fabricated and characterized. Driven with a sinusoidal current of /spl plusmn/20 mA, the fast scanner and the slow one vibrated with an optical scan angle (/spl theta//sub o/) of 1/spl deg/ at the resonant frequency (f/sub r/) of 1.7 kHz and /spl theta//sub o/ of 60/spl deg/ at f/sub r/ of 72 Hz, respectively. Durability was demonstrated with a shock test of 2500 G and a life test of over 13 000 h. By substituting sputtered aluminum driving coil with electroplated copper coil, improved /spl theta//sub o/ of 16.8/spl deg/ was obtained at f/sub r/ of 2.7 kHz.