U.S. Philips Corporation

Karl-Hanns Meyer

Gerard E Van Rosmalen

Wilhelmus A Gijzen

Leonhard Honds

Robert N Van Sluys

Leo Honds

Willy J Aerts

In an electrodynamic actuator for an optical write-in or read-out unit (11), which is aligned with respect to signal tracks of a storage medium in order to direct a focused light beam (13) onto a work position, the actuator includes an optical unit (11) is arranged on a movable permanent magnet arrangement (5, 5a) which can be moved by means of stationary coils (17a, 17b, 19a, 19b) located in its vicinity in focusing (z) and radial (x) directions running perpendicular to one another, the coils being located in the radial direction (x) on both sides of the permanent magnet arrangement (5, 5a), and the magnetization of the permanent magnet arrangement being chosen in such a way that its magnetic field in the region of coils (17c, 17d, 19c, 19d) opposite to it has both an x component and z component, the permanent magnet arrangement (5, 5a) with the optical unit (11) in the magnetic field of the coils is arranged at the free ends of spring rods (3) clamped at one end, and the spring rods (3) of the permanent magnet arrangement (5, 5a) provide flexible support and allow movement perpendicular to the focusing direciton or radial direction.

Electrodynamic actuator for an optical write-in or read-out unit

An electrodynamic actuator for optical storage systems comprising an electromechanical actuating device which is constructed to move an optical write and/or read unit into write or read operating positions relative to a storage medium, comprising a linear motor which comprises spaced apart parallel stator sections, which are constituted by rod-shaped stator iron elements carrying induction coils which are stationary relative to the stator, a permanent magnet being arranged between said stator sections and being guided to be longitudinally movable in a direction of translation between the axial ends of the stator sections. The permanent magnet carries the optical system of the optical unit and has a magnetic field which is oriented perpendicularly to the direction of translation and parallel to a central plane in which the stator irons, the induction coils and the permanent magnet itself are arranged. The permanent magnet is movable between the stator sections relative to the common central plane, a plurality of induction coils are arranged after each other in the longitudinal direction on each rod-shaped stator iron element, and can be switched into and out of circuit separately, and conductor bundles extend parallel to the stator sections between the permanent magnet and the two stator sections and are combined at the axial ends of the stator sections to form one or more focussing coils.

Linear motor actuator for moving an optical read/write head

An optical scanning unit with an objective for the focussing a beam of radiation along an optical axis into a scanning spot on the surface of an information carrier. The scanning unit also has an electromagnetic drive for correcting the position of the objective with respect to the information carrier. The drive has an objective mount supported in an annular, moving magnetic member which is axially magnetized and is arranged coaxially about the optical axis. The drive is further provided with fixed coils which interact with the magnetic member via an air gap. The fixed coils are arranged along at least three radial planes which are normal to the optical axis. Two planes lie in the area of the axial ends of the centrally positioned magnetic member and the third central plane which extends between the two outer radial planes.

Driver for an objective of an optical scanning unit

An optical scanning unit with an objective for focussing a beam into a scanning spot on the surface of an information carrier and an electromagnetic drive for continuous correction of the position of the objective with respect to the information carrier. The objective is mounted in a movable ring-shaped magnetic body of a permanent-magnetic material which is arranged coaxially about the optical axis and which has magnetic poles at the axial ends. The drive is provided with sets of fixed coils which interact with the magnetic body via an air gap. Each set of coils has a first segmental coil arrangement having two active coil parts extending parallel in the peripheral direction of the magnetic body and located in the vicinity of the axial ends of the centrally positioned magnetic body. The unit is further equipped with at least one second coil arrangement which is positioned at least partially between the active coil parts of the above-mentioned first segmental arrangement.

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Aachen, Germany

Karl-Hanns Meyer