OPTICAL SCANNING UNIT

摘要

SUMMARY "Optical scanning unit" Optical scanning unit with an objective (5) with an optical axis for the focussing of a beam of rays into a scanning spot on the surface of an information carrier. The scanning unit also has an electromagnetic drive device for correcting the position of the objective with respect to the information carrier, the drive device being equipped with an objective mounting (7) for the objective. The objective mounting has a moving magnetic body (200) of a permanent-magnetic material which is arranged coaxially about the optical axis and is equipped with magnetic poles. The drive device is further equipped with fixed coils (204, 205, 206) which interact with the said magnetic body via an air gap. The fixed coils are arranged along at least three radial planes, of which two (I and II) lie in the area of the axial ends of the centrally positioned magnetic body and at least one central radial plane (III) extends between the above-mentioned outer radial planes. (Fig.4).