Device for locating a desired information track

Claim 1

A device for controlling the movement of a transducer over a record carrier having a plurality of adjacent information tracks containing information which is converted by the transducer into electrical form, said device comprising control means for moving said transducer relative to the carrier in a direction transverse to the direction of the information tracks, means for applying a starting signal to said control means so that in response thereto said control means moves said transducer over said tracks in said transverse direction, means for producing, during said movement, a periodic signal having a period which depends on the relative transverse velocity of said transducer with respect to said tracks, means for comparing the period of said periodic signal with a predetermined time interval, said comparing means generating a control signal representative of the difference between said period and said predetermined time interval, which control signal is applied to said control means so that in response thereto said transducer is moved by said control means with a constant transverse velocity relative to said tracks, and means for applying a braking signal to said control means just before a desired track is reached in order to enable said transducer to lock on said desired track.

Claim 2

A device for controlling the movement of a transducer over a record carrier having a plurality of adjacent information tracks containing information which is converted by the transducer into electrical form, said device comprising control means for moving said transducer relative to the carrier in a direction transverse to the direction of the information tracks, means for applying a starting signal to said control means so that in response thereto said control means moves said transducer over said tracks in said transverse direction, means for producing, during said movement, a periodic signal having a period which depends on the relative transverse velocity of said transducer with respect to said tracks, means for comparing the period of said periodic signal with a predetermined time interval, said comparing means generating a control signal representative of the difference between said period and said predetermined time interval, which control signal is applied to said control means so that in response thereto said transducer is moved by said control means with a constant transverse velocity relative to said tracks, and means for applying a braking signal to said control means just before a desired track is reached in order to enable said transducer to lock on said desired track.

Claim 6

The device according to claims 4 or 3 wherein said comparing means includes a one-shot which is triggered at a time instant corresponding to a zero passage of said alternating signal so as to produce an output pulse of a predetermined duration and a gate circuit responsive to said output pulse and said alternating signal for supplying said control signal of a duration representative of the time interval between the end of said output pulse and a zero crossing of said alternating signal occurring subsequently to the zero crossing which triggers said one shot.

Claim 10

The device according to claims 1, 2, 3 or 4 including means for counting the tracks passed by said transducer during said transverse movement thereof, and wherein said braking signal applying means is responsive to said counting means.