Optical information reader

Abstract

Abstract PURPOSE: To simplify the constitution of the servomechanism of a reader, by forming the focusing/tracking servo systems with a pair of voice coils which are common to the focusing/tracking electromagnets. CONSTITUTION: The current flows to the coils of the focusing electromagnets 1a and 1b to generate the magnetic field, and the voice coil 3 to which a constant level of current is supplied is displaced upward or downward along with the optical system 4. The current which causes the magnetic field to the magnets 1a and 1b is controlled by a feedback closed loop comprising the phase wave detector 7, oscillator 6, piezo-element 5 and others to carry out the forcusing servo for the system 4. In the same way, the coil 3 moves left or right via the tracking electromagnets 2a and 2b to perform the tracking servo of the system 4. Thus two servo systems is controlled with a pair of voice coils. As a result, the constitution is simplified for both the focusing and tracking servo systems. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Hironoshin Mori

Bibliographic Details