Objective lens driving device

Claim 1

In an objective lens driving device for driving an objective lens and correcting a relative positional error, i.e. a tracking error between an information track recorded spirally or concentrically on a record medium and a light spot projected onto the record medium by means of the objective lens, the improvement comprising a supporting means for movably supporting said objective lens or its holding means in a direction perpendicular to an optical axis of the objective lens as well as the information track; first and second magnetic members arranged at both sides of the objective lens or its holding means as viewed in a direction perpendicular to said moving direction of the objective lens or its holding means and made integral therewith; first, second, third and fourth yokes each including one portion opposed through an air gap to one of the two ends of one of said magnetic members; first, second, third and fourth coils each wound around that portion of said yoke which is opposed to said one end of one of said magnetic members; and a magnetic field generation means for producing a closed loop of magnetic field passing through said first, second, third and fourth yokes as well as said first and second magnetic members; whereby said first, second, third and fourth coils are supplied with an electric current corresponding to a tracking error signal representing said relative positional error so as to displace said first and second magnetic members and said objective lens in a direction perpendicular to its optical axis and to the information track, thereby correcting the tracking error.