U.S. Philips Corporation

Willy J Aerts

Gerard E Van Rosmalen

Wilhelmus A Gijzen

Karl-Hanns Meyer

Leonhard Honds

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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Eindhoven, Netherlands

Willy J Aerts