Appliance for recording or playing back information having means for detecting or moving the scanning location on a disc with a wobble track

Abstract

The invention proposes an appliance for recording or playing back information having means for detecting or moving the position of a scanning device over a disc with a wobble track, said appliance being able to be used both in recorded and in unrecorded areas of the disc and hence being able to be used both for write-once and for rewriteable recording media with a wobble track, and said appliance additionally permitting fast determination of the scanning location without decoding of scanned-location information which is contained in the wobble track. According to the invention, a wobble signal is scanned from the wobble track on the disc using a scanning device, and a wobble frequency contained in the wobble signal detected from the disc is used for detecting or moving the position of the scanning device. In this regard, the wobble frequency is related to the number of revolutions or the rotation speed of the disc or to a wobble frequency known for a reference location on the disc, which allows the position of the scanning device to be detected or moved without decoding of scanning-location information which is contained in the wobble signal. To generate the wobble frequency contained in the wobble signal, a circuit block is provided which contains a phase comparator, a bandpass filter, a voltage-controlled multivibrator and a digital phase shifter and is used to generate a wobble-frequency signal.