| 摘要 |
The automatic correction system for the servo-circuit in a device with optical scanning of a rotating information support has a known servo-circuit which detects anomalies in the scanning system 1, to the outputs of which a gate circuit is connected, and which provides as necessary a mute control signal to the decoder 2 connected to the scanning system 1 and thus mute-controls its outputs. According to the invention, anomalies in scanning caused by external influences and/or disc faults, such as scratches, can to a great extent be weakened in terms of their disruptive appearance by virtue of the fact that a triggering criterion for correction signals can be produced, in the event of anomalies, by sequential address comparison. This is achieved by virtue of the fact that a comparator 6 on each occasion compares newly read data with preceding information, which is temporarily stored in a latch circuit 7, and by virtue of the fact that a preliminary indication is held ready in the form of a measurement window δ D in order to determine whether the comparison lies outside the measurement window and in order then to emit a correction signal from the comparator 6 to the servo system 3, and by virtue of the fact that the latter returns the scanning system 1 to the last valid scanning point. <IMAGE>
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