Servo for video tape apparatus with editing capabilities

Claim 2

A servosystem for a video tape recorder including a capstan servo comprising a motor coupled to the tape capstan, tachometer means responsive to the rotation of the motor for providing a predetermined plurality of electrical pulses during the period between control track pulses from the video tape, means for providing a reference pulse train having a given pulse rate, means responsive to said predetermined plurality of tachometer pulses and to the control track pulses from the video tape for providing a feedback pulse train derived from the control track pulses for operation in a PLAY mode and from the tachometer pulses for operation in a RECORD mode and including means for deriving, during transition from PLAY to RECORD modes, the feedback pulse train from said predetermined plurality of tachometer pulses having a maximum phase deviation in radians from the phase of the control track pulses no greater than 2 pi times the reciprocal value of said predetermined plurality of tachometer pulses, comparing means responsive to said feedback pulse train and to said reference pulse train for providing an error voltage indicative of the phase difference therebetween, and means electrically coupling said error voltage to said capstan motor for providing a motor speed such that said reference and said feedback pulse trains are in continuous phaselocked synchronism.

Claim 3

The system of claim 1 further including a closed-loop head drum servo comprising a second motor coupled to the head drum for rotation thereof, tachometer means responsive to the rotation of the motor for providing a feedback pulse output indicative of the speed thereof, second comparing means responsive to the tachometer feedback pulse output and said reference pulse train for providing a second error voltage indicative of the phase difference therebetween, and means electrically coupling said second error voltage to said head drum motor for providing a motor speed such that said reference and said tachometer feedback pulse trains are in continuous phase-locked synchronism, whereby said head drum motor is phase-locked to the record track in said PLAY mode and to the capstan tachometer in the RECORD mode by the common reference.

Claim 4

The system of claim 1 wherein said predetermined plurality of tachometer pulses is equal to or greater than 32.

Claim 5

The system of claim 1 wherein said comparing means comprises means for providing a first constant level output when the frequency of said feedback pulses is greater than the frequency of said reference pulses and a second constant level output when the frequenCy of said feedback pulse is less than the frequency of said reference pulses and a square wave output when the frequency of said feedback pulses equals the frequency of said reference pulses with the pulse duration of the output varying according to the phase deviation between the feedback and reference pulses, pulse-generating means for providing a ramp voltage pulse coincident with the generation of the square wave pulse, and sampling means responsive to each ramp voltage pulse and to a trigger signal derived from said square wave to derive said error voltage indicative of the phase difference between said feedback and reference pulses.

Claim 6

The system of claim 1 wherein said means for providing a feedback pulse train comprises means responsive to said predetermined plurality of tachometer pulses for supplying a divided output of the same frequency as the control track pulses and having means responsive to each control track pulse for initiating a new count, logic means responsive to the divided output and to the control track pulses for deriving the feedback pulses from the control track pulses regardless of the presence of said divided output, but deriving said feedback pulses from said divided output in the absence of a control track signal, and means responsive to a record command signal for actuating said logic means to derive the feedback pulses from said divided output pulses upon the occurrence of the first control track pulse subsequent to the record command signal.

Claim 7

The system of claim 3 wherein said predetermined plurality of tachometer pulses is an even binary number.

Claim 8

The system of claim 6 wherein said predetermined plurality of tachometer pulses is 64.

Claim 9

The system of claim 1 comprising means for introducing an adjustably variable delay in said reference pulse train for operation in PLAY mode for causing the control track pulses to be coincident with the vertical synchronizing pulses on the video tape and with the synchronizing pulses supplied from material to be assembled, and means for recording the new control track pulses on the video tape for the assembled material, said new control track pulses being derived from said reference pulses.

Claim 10

The system of claim 8 wherein said reference pulses have a frequency of 30 Hz.

Claim 11

A servosystem for a video tape recorder including a capstan servo comprising a motor coupled to the tape capstan, tachometer means responsive to the rotation of the motor for providing a predetermined plurality of electrical pulses during the period between control track pulses from the video tape, means for providing a reference pulse train derivable from the vertical synchronizing pulses of a television signal or a standard frequency source, circuit means responsive to said predetermined plurality of tachometer pulses having a dividing characteristic equal to said predetermined plurality to provide divided output pulses, and to derive a feedback pulse from the control track pulses whenever such a signal is present, but in its absence, from said divided output signal, comparing means responsive to said feedback pulses and to said reference pulses for providing an error voltage indicative of the phase difference therebetween, means electrically coupling said error voltage to the capstan motor for providing a motor speed such that said reference and said feedback pulses are in continuous phase-locked synchronism, and means for deriving control track signals for operation in a RECORD mode from the reference pulses in coincidence with the vertical synchronizing pulses of the tape and with the vertical synchronizing pulses of the material to be assembled, said system further comprising a head drum servo responsive to said reference pulses and to feedback pulses derived from a drum tachometer, whereby the rotation of the video head drum, the tape capstan and the control track pulses are in phase-locked synchronism with said reference pulses.

Claim 12

A servosystem for a video tape recorder including a capstan servo comprising a motor coupled to the tape capstan, tachometer means responsive to the rotation of the motor for providing a predetermined plurality of electrical pulses during the period between control track pulses from the video tape, means for providing a reference pulse train derivable from the vertical synchronizing pulses of a television signal or a standard frequency source, circuit means responsive to said predetermined plurality of tachometer pulses having a dividing characteristic equal to said predetermined plurality to provide divided output pulses, and to derive a feedback pulse from the control track pulses whenever such a signal is present, but in its absence, from said divided output signal, comparing means responsive to said feedback pulses and to said reference pulses for providing an error voltage indicative of the phase difference therebetween, means electrically coupling said error voltage to the capstan motor for providing a motor speed such that said reference and said feedback pulses are in continuous phase-locked synchronism, and means for deriving control track signals for operation in a RECORD mode from the reference pulses in coincidence with the vertical synchronizing pulses of the tape and with the vertical synchronizing pulses of the material to be assembled, said system further comprising a head drum servo responsive to said reference pulses and to feedback pulses derived from a drum tachometer, whereby the rotation of the video head drum, the tape capstan and the control track pulses are in phase-locked synchronism with said reference pulses.

Claim 13

A servosystem for video tape apparatus comprising a capStan motor for driving the video tape, means responsive to a signal on the tape to provide electrical control pulses therefrom, tachometer means responsive to the rotation of the motor for providing a number of electrical pulses during the period between successive control pulses, means for providing a train of electrical pulses having a reference pulse rate, means responsive to the pulses from said tachometer means and to the control pulses for providing a feedback pulse train derived from the control pulses for operation in a PLAY mode and from the tachometer pulses for operation in a RECORD mode and including means for deriving, during transition from PLAY to RECORD modes, the feedback pulse train from the tachometer pulse occurring immediately prior to a control pulse, comparing means responsive to said feedback pulse train and to the train of reference pulses for providing an error signal indicative of the phase difference therebetween, means electrically coupling said error signal to said capstan motor for varying the speed of said motor in a manner to reduce said phase difference, and means for generating a sufficiently high predetermined number of tachometer pulses during said period between control pulses so that deviation of phase between the control pulses and each tachometer pulse occurring just prior to each respective control pulse during the PLAY mode is sufficiently small to provide no loss of phase-lock in the apparatus during the mode transition.

Claim 14

A servosystem for video tape apparatus comprising a capStan motor for driving the video tape, means responsive to a signal on the tape to provide electrical control pulses therefrom, tachometer means responsive to the rotation of the motor for providing a number of electrical pulses during the period between successive control pulses, means for providing a train of electrical pulses having a reference pulse rate, means responsive to the pulses from said tachometer means and to the control pulses for providing a feedback pulse train derived from the control pulses for operation in a PLAY mode and from the tachometer pulses for operation in a RECORD mode and including means for deriving, during transition from PLAY to RECORD modes, the feedback pulse train from the tachometer pulse occurring immediately prior to a control pulse, comparing means responsive to said feedback pulse train and to the train of reference pulses for providing an error signal indicative of the phase difference therebetween, means electrically coupling said error signal to said capstan motor for varying the speed of said motor in a manner to reduce said phase difference, and means for generating a sufficiently high predetermined number of tachometer pulses during said period between control pulses so that deviation of phase between the control pulses and each tachometer pulse occurring just prior to each respective control pulse during the PLAY mode is sufficiently small to provide no loss of phase-lock in the apparatus during the mode transition.

Claim 15

The system of claim 11 further comprising a head drum motor, second tachometer means responsive to the rotation of the head drum motor for providing a feedback pulse output indicative of the speed thereof, second comparing means responsive to the second tachometer feedback pulse output and said reference pulse train for providing a second error signal indicative of the phase difference therebetween, and means electrically coupling said second error signal to said head drum motor for varying the speed of the motor in a manner to reduce the phase difference, whereby said head drum motor is phased-locked to said control signals in the PLAY mode and to the capstan tachometer pulses in the RECORD mode by the common reference pulse train.

Claim 16

The system of claim 11 wherein said means for providing a feedback pulse train comprises a divider for producing one output pulse for every said predetermined number of pulses to provide an output pulse rate equal to that of said control pulses, and means for resetting said divider on the occurrence of each of said control pulses.

Claim 17

The system of claim 13 wherein said means for providing a feedback pulse train further comprises logic means responsive to said output pulses and to said control pulses for deriving said feedback pulses from the control pulses when said control pulses are present and from said output pulses when said control pulses are absent, and means responsive to a record command signal for actuating said logic means to derive said feedback pulses from said output pulses upon the occurrence of the first control pulse subsequent to the record command signal.

Claim 18

A servosystem for video tape apparatus comprising a capstan motor for driving the video tape, means responsive to a signal on the tape to provide electrical control pulses therefrom, tachometer means responsive to the rotation of the motor for providing a predetermined number of electrical pulses during the period between successive control pulses, means responsive to the pulses from said tachometer means and to the control pulses for providing a feedback pulse train derived from the control pulses for providing a feedback pulse train derived from the control pulses for operation in a PLAY mode and from other pulses for operation in a RECORD mode and including a scaler for producing one of said other pulses for every predetermined number of tachometer pulses, an means for resetting said scaler on the occurrence of each of said control pulses, said tachometer means generating a suffIciently high predetermined number of tachometer pulses during said period between control pulses so that deviation of phase between the control pulses and each tachometer pulse occurring just prior to each respective control pulse during the PLAY mode is sufficiently small to provide no loss of phase-lock in the apparatus during transition from the PLAY mode to the RECORD mode.

Claim 19

A servosystem for video tape apparatus comprising a capstan motor for driving the video tape, means responsive to a signal on the tape to provide electrical control pulses therefrom, tachometer means responsive to the rotation of the motor for providing a predetermined number of electrical pulses during the period between successive control pulses, means responsive to the pulses from said tachometer means and to the control pulses for providing a feedback pulse train derived from the control pulses for providing a feedback pulse train derived from the control pulses for operation in a PLAY mode and from other pulses for operation in a RECORD mode and including a scaler for producing one of said other pulses for every predetermined number of tachometer pulses, an means for resetting said scaler on the occurrence of each of said control pulses, said tachometer means generating a suffIciently high predetermined number of tachometer pulses during said period between control pulses so that deviation of phase between the control pulses and each tachometer pulse occurring just prior to each respective control pulse during the PLAY mode is sufficiently small to provide no loss of phase-lock in the apparatus during transition from the PLAY mode to the RECORD mode.

Claim 20

The system of claim 15 wherein said means for providing a feedback pulse train further comprises logic means responsive to said other pulses from the scaler and to said control pulses for deriving said feedback pulses from the control pulses when said control pulses are present and from said other pulses when said control pulses are absent, and means responsive to a given signal for actuating said logic means to derive said feedback pulses from said other pulses upon the occurrence of the first control pulse subsequent to said given signal.