LENS DRIVING DEVICE, OPTICAL HEAD AND OPTICAL DISC SYSTEM

摘要

A RECORDING/REPRODUCING APPARATUS FOR AN OPTICAL RECORDING MEDIUM (2) IN WHICH A LASER LIGHT BEAM IS ILLUMINATED ON AN OPTICAL RECORDING MEDIUM (2) USING A DOUBLE-LENS TYPE OBJECTIVE LENS MADE UP OF AT LEAST A FIRST LENS (3) AND A SECOND LENS (4) TO RECORD AND/OR REPRODUCE THE INFORMATION. THE APPARATUS INCLUDES A FIRST LENS (3) FOR CONVERGING THE LASER LIGHT ILLUMINATED FROM A LIGHT SOURCE, A SECOND LENS (4) ARRANGED BETWEEN THE FIRST LENS AND THE OPTICAL RECORDING MEDIUM (2) AND A VOICE COIL MOTOR FOR CAUSING RELATIVE MOVEMENT OF THE FIRST AND SECOND LENSES (3,4) FOR VARYING THE DISTANCE THEREBETWEEN IN THE DIRECTION ALONG THE OPTICAL AXIS. THE FIRST LENS (3) IS MOVED TO VARY THE DISTANCE BETWEEN THE FIRST AND SECOND LENSES. THIS ENLARGES THE NUMERICAL APERTURE AND DIMINISHES THE EFFECT OF ABERRATION TO ENABLE HIGH-DENSITY RECORDING AND/OR REPRODUCTION OF INFORMATION SIGNALS TO A HIGH RECORDING DENSITY. (FIGURE 2)