U.S. Philips Corporation

Friedrich Sommer

Uwe Jahnke

Hendrik J Sanderson

Jacob De Boer

Erich Langer

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 circuit arrangement for phase-alignment of a servo drive for a rotary system, to whose correction element for correcting the speed of said system the output signal of a phase detector is applied via a transmission path which output signal determines the mutual phase relationship of an actual signal and of the desired signal, comprises two gate circuits of which one circuit receives the pulse-shaped actual signal and the other circuit receives the pulse-shaped desired signal as an input signal, and whose output signals are applied to the transmission path in phase opposition for phase-alignment of the rotary system, each of the gate circuits being controlled by a bistable multivibrator which can also be changed over by said actual and desired signals, so that a gate circuit is opened only when its input signal contains more than one pulse between two consecutive pulses in the input signal of the other gate circuit.

Circuit arrangement for phase-alignment of a servo drive for a rotary

The invention relates to a recording and playback apparatus for video signals including a drive shaft for driving a record carrier, whose revolution speed can be controlled by a servo system, and a switching device to ensure that a new recording without interruption follows an existing recording, said apparatus comprising a measuring and storage device for measuring and storing the difference in phase between the pulses supplied by the tacho-generator and the pulses scanned from the synchronizaton track which device is followed by a comparator, for comparing the stored measuring value with the reference signal for the servo system, which comparator if its input signals are equal supplies its output signal to the servo system as the measuring signal. Such a servo system prevents the occurrence of undesired phase shifts at the transition from the existing recording to the new recording. The stored value, representing the phase difference between the tach signal and the recorded vertical sync signal, controls the delay of the tach signals when a new video insert is added.

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Vienna, Austria

Friedrich Sommer