Auto-tracking method and apparatus of a magnetic recording/reproducing apparatus
AssigneesHitachi Microcomputer Hitachi, Ltd., Engineering Corporation
InventorsYasunori Kobori, Hideo Nishijima, Kaneyuki Okamoto, Isao Fukushima, Katsuhiko Goto, Takashi Takahashi
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Abstract
An auto-tracking method and apparatus of a helical scan type magnetic recording/reproducing apparatus wherein envelope levels of reproduced signals are detected and the running phase of a magnetic tape is controlled so that the envelope level of the reproduced signal becomes maximum after detection is effected roughly and then finely, thereby allowing a video head to scan a track on the magnetic tape.
Claims9
An auto-tracking apparatus which is used in a magnetic recording/reproducing apparatus of the helical scan system and which serves to control a rotation of a rotary cylinder and a run of a magnetic tape such that at least two magnetic heads attached to the rotary cylinder accurately scan tracks on the magnetic tape, comprising:
- reference signal generating means for generating a reference signal;
- rotary cylinder driving means for driving said rotary cylinder to rotate said magnetic heads synchronously with said reference signal;
- head switching signal generating means for detecting a rotational phase of said rotary cylinder and outputting a head switching signal representative of said rotational phase;
- envelope detecting means for sampling and detecting envelope levels of reproduced signals from said tracks detected by said magnetic heads at timings based on said head switching signal;
- magnetic tape running means for allowing the magnetic tape to run in response to a tape running control signal which is inputted to said magnetic tape running means, said running means including tape running control means for controlling the run of said magnetic tape such that the magnetic tape runs at a phase having a phase difference corresponding to a delay time responsive to said reference signal of said running control signal with respect to the rotational phase of said rotary cylinder;
- and
- means for generating said tape running control signal on the basis of said detected envelope levels, reference signal and head switching signal, said means including:
- reference signal delay means, connected to receive said reference signal, for delaying said reference signal received and outputting the delayed reference signal as said tape running control signal;
- and delay control means, connected to said reference signal delay means, for controlling said reference signal delay means such that said reference signal delay means first changes the run of said magnetic tape at rough steps within a first predetermined tracking phase range on the basis of said head switching signal and said detected envelope levels and thereby detecting the roughly searched maximum envelope level of said reproduced signals, and after completion of the detection of said roughly searched maximum envelope level, changes the run of the magnetic tape at fine steps within a second predetermined tracking phase range which is narrower than said first predetermined tracking phase range and which includes the running phase of the magnetic tape corresponding to said roughly searched maximum envelope level to thereby detect the finely searched maximum envelope level of the reproduced signals and output a signal having the phase corresponding to said finely searched maximum envelope level as said tape running control signal.
An auto-tracking apparatus of a magnetic recording/reproducing apparatus of the helical scan system in which a run of a magnetic tape is controlled by a signal representative of a phase difference between a reference signal and a signal indicative of a running phase of said magnetic tape, comprising:
- first means for delaying said reference signal;
- a second means for periodically detecting an envelope level of a frequency modulated video signal reproduced by a rotary head;
- third means for sequentially changing a delay time of said first means at a rough pitch within a predetermined first range each time said second means detects said envelope level so as to detect a first delay time of said first means such that said envelope level becomes maximum;
- and
- fourth means for sequentially changing the delay time of said first means at a fine pitch within a predetermined second range including said first delay time detected by said third means each time said second means detects said envelope level so as to detect a second delay time of said first means such that said envelope level becomes maximum,
- wherein by delaying said reference signal by setting said second delay time into said first means, the phase of said reference signal is accurately and rapidly to thereby obtain the best tracking state.
An auto-tracking method for controlling a run of a magnetic tape in a magnetic recording/reproducing apparatus of a helical scan type so that rotary magnetic heads accurately scan tracks on the magnetic tape, comprising the steps of:
- changing the running phase of said tape at rough steps over a first predetermined tracking phase for detecting a first maximum envelope level of a reproduced signal recorded on said tape;
- changing the running phase of said tape at fine steps over a second predetermined tracking phase range which is narrower than the first range and extends around a tracking phase corresponding to said first maximum envelope level, for detecting a second maximum envelope level of said reproduced signal;
- and
- setting the running phase of said tape to a value corresponding to said second maximum envelope level.
Dependencies are inferred from the claim text.