Objective lens driving device

Abstract

Abstract PURPOSE:To simplify a magnetic field switching circuit by providing a pair of coils for a focus and a coil for a track at both sides of an objective lens, arranging first and second magnetic circuits to give a magnetic field to respective coils and making non-symmetrical the polarity of a magnet used for the second magnetic circuit. CONSTITUTION:An inside surface 21a of one side magnet 18a comes to be an N pole, an outside surface 23a comes to be an S pole and in the direction shown by an arrow phia in a magnetic gap 22a, a magnetic field is formed. An inside surface 21b of other side magnet 18b comes to be the S pole, an outside surface 23b comes to be the N pole and in the direction shown by an arrow phib in a magnetic gap 22b, the magnetic field is formed. Thus, since the polarity of the magnet used for first and second magnetic circuits 17a and 17b is made non-symmetrical, the direction of the leaking magnetic flux at the spot position of the recording medium, in which a laser light is converged, comes to be in parallel to the recording medium. Consequently, the magnetic field vertical to the recording medium impressed to the spot position by a magnetic field impressing means is not influenced by the leaking magnetic flux. Thus, the switching circuit to switch the direction of the magnetic field, namely, the direction of the current is simplified.

Inventors

• 👤 Yutaka Mazaki
• 👤 裕 真崎
• 👤 Isamu Nose
• 👤 能勢　勇

Bibliographic Details