LENS POSITION SENSOR OF OBJECTIVE LENS ACTUATOR

摘要

PURPOSE:To obtain the simple position sensor having high accuracy by providing a slit of a specific length in a focusing direction on the light shielding plate of the lens position sensor and detecting the position in a tracking direction by the light past this slit. CONSTITUTION:A reference plane 23b and the slit 23a which is in parallel with the reference plane 23b and longer than the sum of the size in the tracking direction F of the light receiving surface 41a of a light receiving element 41 and the movable stroke in the focusing direction F of a bobbin 2 are provided on the light shielding plate 23. The reference plane 23b is mounted on the positioning surface 6a provided on the bobbin 2 in parallel with the optical axis of an objective lens 1 and the position in the tracking direction of the bobbin 2 is detected by the exit light form a light emitting element past the slit 23a. The exit light past the slit 23a falls over the entire part of the focusing direction of the light receiving surface 41a and, therefore, the mis-registration of the detection is prevented.