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

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 ±20 mA, the fast scanner and the slow one vibrated with an optical scan angle (θ_o) of 1° at the resonant frequency (f_r) of 1.7 kHz and θ_o of 60° at f_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 θ_o of 16.8° was obtained at f_r of 2.7 kHz