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AssigneeU.S. Philips Corporation
InventorsPeter J. M. Janssen, Gerard E. van Rosmalen
Estimating the term…
An opto-electronic apparatus for inscribing and/or reading recording tracks on a record carrier by means of a radiation beam comprises an objective mounted in an objective holder. The objective holder is supported in a frame by bearing arrangement for movement in accordance with a number of desired degrees of freedom and the apparatus includes electromagnetic actuator means for driving the objective holder in accordance with the desired directions of movement. The bearing arrangement of the objective holder on the frame comprises electromagnetic bearing means for counteracting movements in accordance with at least one undesired degree of freedom. An objective-position measuring device supplies a positional error signal which represents the deviation of the objective holder in accordance with the undesired degree of freedom relative to the frame and which is utilized by a levitation control circuit which counteracts movements of the objective holder relative to the frame in accordance with the undesired degree of freedom by means of electromagnetic levitation forces.
An apparatus for inscribing and/or reading recording tracks in a recording surface of a record carrier with a radiation beam, which apparatus comprises:
Apparatus for inscribing and/or reading recording tracks in a recording surface of a record carrier with a radiation beam, said apparatus comprising a frame, a holder, an objective for concentrating the radiation beam so as to form a radiation spot in a focusing plane, said objective having a optical axis and being mounted in said holder, means for supporting said holder on said frame for movement relative to said frame in a desired number of directions of movement out of six, independent directions of movement consisting of translational movement parallel to each of three orthogonal axes one of which coincides with said optical axis and rotational movement about each of said orthogonal axes, means for counteracting movement of said holder in at least one other, undesired, direction of movement, said counteracting means including a coil secured to one of said frame and holder and magnetic means arranged on the other of said frame and holder and cooperating with said coil to produce an electromagnetic force which opposes movement of said holder relative to said frame in said undesired direction of movement, means for moving said objective relative to said frame in each of said desired directions of movement, means for detecting displacement of said objective from a given position relative to said frame in said undesired direction of movement, said detecting means generating a positional error signal representative of said displacement, means responsive to said error signal for applying to said coil a current dependent on said error signal such that said electromagnetic force produced by said coil and said magnetic means moves said holder to said given position upon displacement therefrom.
Dependencies are inferred from the claim text.