Ampex Corporation

International Video Corporation

Kenneth Louth

Luigi C Gallo

Reginald W Oldershaw

An improved reel servo for a recording and reproducing machine is disclosed. The reel servo as well as other servos in the machine are controlled by a single microprocessor which results in greater inherent communication between such servos and significantly improved operating capabilities. The reel servo itself is adapted to have the supply and take-up reels operate in different kinds of close loop servo control during various operating modes. The servo circuitry provides instantaneous information to the microprocessor for determining the diameter of tape that is wrapped on each of the reels. The reel servo has the capability of performing high speed shuttle and cueing operations without engaging the capstan and the tensioning arm can be positioned to provide the appropriate tape tension during shuttling in both the forward and reverse directions. An acceleration loop controls the supply reel so that the tape tension is maintained within predetermined upper and lower limits.

Head reel servo system in a recording and/or reproducing apparatus

A microprocessor controlled multiple servo system for use with a recording and reproducing apparatus is disclosed. The system controls all servo systems for a magnetic tape recording and reproducing apparatus, including a capstan servo, a reel servo, a scanning drum servo and an automatic scan tracking servo which controls the position of reproduced heads carried by the scanning drum which are of the type which can be transversely moved relative to the longitudinal direction of recorded tracks to accurately follow the tracks during special effect reproducing modes, such as slow motion, stop motion and fast motion reproducing. The microprocessor controlled servo system has unique and powerful functional capabilities which enable it to provide reliable precise asynchronous reproducing so that precisely accurate time compression and expansion can be carried out without performing any editing of the recorded material.

Microprocessor controlled reproducing apparatus having asynchronous

A phase detection control apparatus is disclosed for detecting any variable where the phase is discretely measured, as for example, in a motor having a tachometer of an optical type. The phase detection apparatus eliminates direction sensitivity and does not suffer from the misposition of any upper and lower limits. The apparatus achieves a phase lock without excessive overshoot and eliminates the possibility of reverse run away under any condition. Moreover, the circuitry is easily implemented with a relatively few number of circuit components and therefore accomplishes the desirable functional capabilities at relatively low cost.

Phase detector control for a servo system

An improved automatic scan tracking servo for use in a magnetic recording and reproducing apparatus is disclosed. The automatic scan tracking servo operates generally in the digital domain. The apparatus has a movable element which is transversely moved relative to the longitudinal direction of a recorded track so that the transducing head can be made to accurately follow the track during special motion reproducing modes. The RF video signal is sampled a predetermined number of times during each rotation of the scanning drum carrying the transducing head. The phase of the oscillatory motion or dither that is applied to the movable element carrying the head, the operation of a synchronous detector and the sampling are all totally synchronized to obtain an accurate error signal so that an accurate error correcting signal can be generated to have the transducing head accurately follow a track during such reproducing. The servo utilizes the longitudinal tape speed to provide a predicted value of the slope of the ramp that is required to have the head follow the track and the error correcting signal merely modifies the ramp in accordance with the actual error that is detected. The combination of the synchronism and the predicted value of the slope enables a reduced dither amplitude to be used to obtain an accurate error signal.

Automatic scan tracking servo system

A monlinear speed control for special motion reproducing of a video recording and reproducing apparatus is disclosed. The apparatus is of the type which has an automatic scan tracking servo which controls the position of the reproduced heads carried by the scanning drum which are of the type which can be transversely moved relative to the longitudinal direction of recorded tracks so as to accurately follow the tracks during variable speed special effect reproducing modes. The nonlinear control controls the longitudinal tape speed through the capstan servo and provides vernier control where it should be desirably located so that the operator can accurately control the special effect speeds. The nonlinear control also automatically compensates for changes in the speed and introduces a delay in the response to rapid changes that may occur at high speed special motion reproducing so that visually disturbing rapid changes in the video image will not be experienced by a viewer.

Programmable non-linear speed control for a recording and/or reproducing

A microprocessor controlled multiple servo system adapted for use with a recording and reproducing apparatus is disclosed. The system controls all servo systems for a magnetic tape recording and reproducing apparatus, including a capstan servo, a reel servo, a scanning drum servo and an automatic scan tracking servo which controls the position of reproduce heads carried by the scanning drum which are of the type which can be transversely moved relative to the longitudinal direction of recorded tracks so as to accurately follow the tracks during special effect reproducing modes, such as slow motion, stop motion and fast motion reproducing. The microprocessor controls all of the servos in a way which permits interaction between the various servo systems and enables more accurate and powerful functional operation of the entire apparatus.

Microprocessor controlled multiple servo system for a recording and/or

An improved microprocessor controlled scanning drum servo adapted for use in a recording and reproducing apparatus is disclosed. The scanner servo includes a velocity loop as well as a position loop, and by virtue of the fact that it is controlled by a microprocessor in a unique way, has extraordinary accuracy because the resolving power of the servo is essentially that of the microprocessor itself. The interrupts to the microprocessor occur in sequence with a first interrupt causing the microprocessor to cease current activity, store all required information in a stack register and thereafter wait until a subsequent interrupt occurs which enables it to immediately act to perform control operations with respect to the scanner servo. This enables the velocity loop to perform the vast majority of the work required by the servo and as a result of this, the phase closed servo loop operates as a positioning loop in the true sense.

Head scanning servo system in a recording and/or reproducing apparatus

Apparatus is disclosed for phase locking the output of a voltage controlled oscillator to a self-clocking data pulse stream occurring at a basic predetermined rate, the data stream being of the kind in which the data content is determined by a signal state change located in one of two positions within the data cell interval of the data stream. Each signal state change is defined by a narrow data pulse. The oscillator is controlled by a first means to operate at the predetermined rate when the data pulses are not present and by a second means when the data pulses are present. The second means compares one selected transition of the clock pulses of the oscillator output signal to the position of the data pulse and provides a variable control voltage to the oscillator to adjust its phase so that the the selected clock pulse transition is synchronized to occur at the midpoint of the data pulses.

Phase lock loop for data decoder clock generator

A method and apparatus is disclosed for use in a record/playback system for providing improved alignment between a transducer and a track on a recording medium on which track information has been recorded. The direction and magnitude of any misalignment between the transducer and the track is represented by an error signal. When the error signal indicates substantial alignment between the transducer and the track, a train of equally spaced pulses is generated. When the error signal indicates misalignment between the transducer and the track, at least one pulse is either added or deleted from the train of pulses, depending on the direction of misalignment indicated by the error signal. The pulse train is then used to generate a drive signal for effecting relative motion between the transducer and the track, the phase of the drive signal varying in response to the addition or deletion of pulses from the pulse train. The drive signal has a constant phase when the pulses are equally spaced, and has its phase altered in one of two selected directions when pulses are either added or deleted from the pulse train. By thus varying the phase of the drive signal, alignment between the transducer and the track is improved.

Automatic tracking for a playback transducer

Motor drive and servo systems particularly useful in high quality broadcast video tape recorders. A sine/cosine drive for a brushless DC motor permits high motor efficiency in a system adapted for use in a servo loop. A technique for phase locking a pair of frequency related phase locked control variable signals to a pair of frequency related reference signals, horizontal and vertical sync signals, for example, provides the advantages and precision of closed loop correction at widely variable correction rates. More accurate tape shuttling in a VTR is provided by running a DC motor in a phase locked loop as a synchronous motor and more accurate stopping of the tape is provided by comparing the capstan speed to ground in a closed loop. Improved tape tension control in the head area is provided by a pair of vacuum columns controlled by an error signal derived from the peak-to-peak tension error.

Video tape recorder method and apparatus

An unknown tape pack diameter is determined by measuring the inertia of the unknown tape pack and comparing the inertia with an inertia value representative of the inertia of a second tape pack of known diameter.

Growing community of inventors

Los Altos, CA, United States of America

Kenneth Louth