Apparatus for detecting information index signal from magnetic tape

Claim 1

An apparatus for generating a count signal from a magnetic tape comprising a tape take-up shaft adapted to be driven for rotation at a uniform rate during a rapid advance or rewind of the tape for taking up the magnetic tape in which a plurality of information items are recorded, a first pulse generator responsive to the rotation of the tape take-up shaft to produce a reference pulse signal, a tape supply shaft adapted to rotate as the tape is taken up on the take-up shaft with a rotational speed which increases with an increasing diameter of tape roll on the take-up shaft, a second pulse generator responsive to the rotation of the tape supply shaft to produce a pulse signal at a rate which depends on the varying speed of the supply shaft, means for counting the number of pulses produced per unit time by the first and second pulse generators, a logic circuit for converting a ratio of the number of both pulses into a continuous voltage value which is proportional to the varying tape speed, a detecting head for detecting a signal-free area between adjacent information items recorded on the magnetic tape, an AND gate enabled by a detection signal from the detecting head for passing clock pulses from a clock pulse generator, a pulse counter for receiving clock pulses from the AND gate, and a comparator receiving the count output from the pulse counter and a voltage value from the logic circuit and converting the count output into a corresponding voltage value, the comparator producing a count signal for information retrieval only upon coincidence between the both voltage values.

Claim 2

An apparatus for generating a count signal from a magnetic tape comprising a tape take-up shaft adapted to be driven for rotation at a uniform rate during a rapid advance or rewind of the tape for taking up the magnetic tape in which a plurality of information items are recorded, a first pulse generator responsive to the rotation of the tape take-up shaft to produce a reference pulse signal, a tape supply shaft adapted to rotate as the tape is taken up on the take-up shaft with a rotational speed which increases with an increasing diameter of tape roll on the take-up shaft, a second pulse generator responsive to the rotation of the tape supply shaft to produce a pulse signal at a rate which depends on the varying speed of the supply shaft, means for counting the number of pulses produced per unit time by the first and second pulse generators, a logic circuit for converting a ratio of the number of both pulses into a continuous voltage value which is proportional to the varying tape speed, a detecting head for detecting a signal-free area between adjacent information items recorded on the magnetic tape, an AND gate enabled by a detection signal from the detecting head for passing clock pulses from a clock pulse generator, a pulse counter for receiving clock pulses from the AND gate, and a comparator receiving the count output from the pulse counter and a voltage value from the logic circuit and converting the count output into a corresponding voltage value, the comparator producing a count signal for information retrieval only upon coincidence between the both voltage values.