US 5,327,410 AGranted

Direction-determination logic as for a signal pickup in recorded signal recovery apparatus

AssigneeDeutsche Thomson-Brandt GmbH

InventorsGunter Gleim, Friedrich Fuldner, Bernd Rekla

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Abstract

Direction determining logic for a regulation circuit which guides a detection device along the data tracks of a recording medium receives an HF signal indicating when the detection device scans a dirty or damaged area of the recording medium, and a tracking error signal when the detection device leaves the track. The direction determining logic includes first and second multiple input terminal logic gates for respectively providing first and second complimentary output signals. A bistate logic circuit is selectively responsive to the HF signal and the tracking error signal and provides complementary output signals to one input terminal of each of the multiple input terminal logic gates. Other logic selectively inhibits the other input terminal of one of the multiple input terminal logic gates as the detection device scans a dirty or damaged area of the recording medium and the other of the multiple input terminal logic gates when the tracking device leaves the track.

Claims8

Dependent claims

In apparatus for recovering signal from a recorded medium, circuitry to control the guidance of a detection device along tracks of said recorded medium comprising:

a source of bilevel tracking error signal;
a source of a bilevel representation of the envelope of signal recovered from said recorded medium;
a source of signal indicating when said detection device crosses said tracks;
logic circuitry, responsive to said bilevel tracking error signal and said bilevel representation of the envelope, for generating a direction signal having first and second states for indicating the direction of track crossings of said detection device, said logic circuitry arranged to detect the direction of track crossings only when track crossings occur at a rate less than a predetermined rate, and to maintain the one of said first and second states last exhibited when said rate of track crossings exceeded said predetermined rate, said logic circuitry including;
first circuitry for producing a signal representative of the portions of said bilevel representation of the envelope when transitions of said bilevel representation of the envelope alternate with transitions of said bilevel tracking error signal;
second circuitry for producing a signal representative of the portions of said bilevel tracking error signal when occurrences of transitions of said bilevel representation of the envelope alternate with occurrences of transitions of said bilevel tracking error signal;
and
a bistable circuit responsive to said signal representative of portions of said bilevel tracking error signal and said signal representative of the portions of said bilevel representation of the envelope for producing said direction signal.

5 more elements

Dependencies are inferred from the claim text.