U.S. Philips Corporation

Jacob De Boer

Hendrik J Sanderson

Anthonie Walraven

Friedrich Sommer

A two-head recorder in which information is read from recording tracks which are substantially parallel to each other and which make an angle with the longitudinal axis of a tape-like recording medium. The recorder comprises two heads which are each mounted on a transducer for moving the head as a function of tracking signals for the two heads which appear alternately so that the two heads are alternately centered relative to the recording track. The tracking signals are also applied to a tape speed control circuit in order to control the speed of the tape-like recording medium depending upon the average value of the tracking signals.

Tape speed control device

A phase comparison circuit for comparing first and second pulse trains applied to first and second inputs (1 and 2) respectively, comprises a sawtooth signal generator (11,3) which is phase-locked to the first pulse train (V.sub.A) by means of a frequency control loop comprising a first sampling circuit (4,5) and an amplifier (12). The output signal of the sawtooth generator is sampled when each pulse occurs in the second pulse train (V.sub.B) by means of a second sampling circuit (8,9). In order that a phase difference of zero between the two pulse trains can be accurately determined, whatever their actual repetition frequency, the output signal of the arrangement is formed by means of a differential amplifier (10) as the difference between the output signals of the two sampling circuits.

Phase comparison circuit

A magnetic tape drive arrangement without pressure roller, having a signal generator which generates a signal T, derived from the capstan motor current and the capstan speed. The is proportional to the instantaneous torque exerted on the magnetic tape by the capstan, which signal T controls the supply and/or take-up motors in such a way that this signal is minimized, so that a slip-free magnetic-tape drive without pressure roller is possible.

Magnetic tape drive arrangement

A servo system for controlling the position of a magnetic reading head relative to the center of a selected information track. During recording a long-wave positioning signal is recorded below the data signal in the tracks. Upon reading out, the head not only reads the information of the selected track but, as result of cross-talk, also the positioning signals of the adjacent tracks. After filtering out and processing the positioning signals, a control signal for controlling the head is obtained.

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Eindhoven, Netherlands

Jacob De Boer