Method and apparatus for tracking control
AssigneeSony Corporation
InventorHitoshi Sakamoto
Life of this patent
Estimating the term…
Abstract
A method and apparatus for controlling the movement of a record medium, such as a tape, having skewed record tracks which are scanned by a transducer, such as a playback head. The record medium is commanded to be transported at a speed and for a distance which may be arbitrarily variable. While the record medium is moved, successive record tracks are scanned by the transducer; and the phase difference between the scanned track and the scanning trace of the transducer is detected. The speed at which the record medium is transported is derived from the command; and this speed is adjusted as a function of the detected phase difference.
Claims32
A method of controlling the movement of a record medium having record tracks therein which are scanned by a transducer, said tracks being skewed relative to the direction in which said record medium is moved and said transducer being driven to scan traces generally disposed at an angle to said tracks, said method comprising the steps of commanding said record medium to be transported;
- detecting the phase differences between a record track being scanned and the trace of said transducer when said record medium has been commanded to be transported by a predetermined incremental amount;
- transporting said record medium in response to said command;
- deflecting said transducer in a direction generally transverse with respect to said track being scanned and by an amount which depends in part on the position of said transducer along the length of said track being scanned, whereby said angle is minimized;
- and adjusting the speed at which said record medium is transported as a function of said detected phase difference.
A method of controlling the movement of a video tape having skewed record tracks recorded thereon which are scanned by a playback head to carry out playback operations at different playback speeds in different playback modes wherein successive traces of said head are at an angle to said tracks as a function of said playback speed and playback mode, comprising the steps of generating command pulses, each commanding incremental movement of said tape at a speed which is a function of the rate at which said command pulses are generated;
- counting said command pulses to shift the track being scanned by said head when a predetermined number of command pulses is counted;
- deflecting said head in a direction generally transverse with respect to said track being scanned and by an amount which depends in part on the position of said head along the length of said track being scanned, whereby said angle is minimized notwithstanding the playback speed and playback mode;
- transporting said tape as a function of said command pulses so that said tape is nonuniformly driven by a predetermined incremental distance in response to each command pulse;
- sensing the phase difference between a track being scanned and the scanning trace of said head due to the nonuniform driving of said tape;
- and adjusting the speed at which said tape is driven as a function of the sensed phase difference.
Apparatus for controlling the movement of a record medium having successive skewed tracks recorded thereon, which tracks are scanned by a movable transducer, comprising command means for generating a command signal to command movement of said record medium at a conmanded speed;
- transport means responsive to said command signal to transport said record medium;
- phase detecting means for detecting the relative phase difference between a scanned track and a trace scanned by said transducer, said phase difference being a function, at least in part, of errors in the response of said transport means to said command signal;
- deflecting means for deflecting said transducer in a direction generally transverse with respect to said scanned track and by an amount which depends in part on the position of said transducer along the length of said scanned track to make each of said traces substantially parallel to said tracks;
- and speed adjustment means responsive to the detected phase difference for adjusting said transport means to reduce said detected phase difference.
Dependencies are inferred from the claim text.