Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-07-16
2001-05-22
Nguyen, Huy (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06236800
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a helical scanning type magnetic recording and reproducing apparatus for recording and reproducing signals with rotary magnetic heads on and from a magnetic tape during intermittent and continuous travelling in the forward and backward directions.
Helical scanning type magnetic recording and reproducing apparatuses record and reproduce signals with rotary magnetic heads on and from a magnetic tape wound around a drum assembly having an upper drum and a lower drum. This type of apparatuses have widely been used as a video tape recorder (VTR) or a video cassette recorder (VCR).
The helical scanning type magnetic recording and reproducing apparatus is provided with a pair of rotary magnetic heads for high density recording. The rotary magnetic heads have magnetic gaps with azimuth angels set as reverse to each other.
Recording is carried out with the rotary magnetic heads so that tracks are sequentially and alternately recorded on a magnetic tape such that the tracks are inclined to the longitudinal direction of the magnetic tape. A video signal for one field period is usually recorded or reproduced for each track on or from the magnetic tape.
The helical scanning type magnetic recording and reproducing apparatus have further been used as a monitoring apparatus with a TV camera for crime prevention. Such apparatus is usually a time-lapse type magnetic recording and reproducing apparatus that picks up a video signal for one field or one frame period per specific period of time from sequential video signals output by the TV camera. The time-lapse type magnetic recording and reproducing apparatus has widely been used in banks, supermarkets and convenience stores, etc.
The time-lapse type magnetic recording and reproducing apparatus uses a magnetic tape of a specific length. For long time recording, the magnetic tape is intermittently transferred at a speed corresponding to a normal reproduction for each specific period of time for recording still pictures from the sequential video signals.
Or, a video signal for each specific period of time may be recorded on the magnetic tape while stopped among the sequential video signals for still picture recording. The magnetic tape is transferred by a specific distance and stopped for next still picture recording.
Or, a video signal for each specific period of time may be recorded on the magnetic tape travelling at a slow speed among the sequential video signals for still picture recording.
The recording methods described above complete a recording operation to one magnetic tape when recording is completed from the beginning to end of the magnetic tape. For long time recording, the magnetic tape thus must be rewound to the beginning or exchanged to another one.
Japanese laid Open patent Nos. 50(1975)-85316 and 3(1991)-194701 disclose VTRs for reciprocating recording in both the forward and reverse directions. However, the VTR disclosed in the Japanese Laid-Open patent No. 50(1975)-85316 has many rotary heads. Further, this Laid-Open patent teaches variation of angle at which a magnetic tape is wound around a drum. The Laid-Open patent thus cause a problem of incompatibility to a standard VTR.
Further, the other VTR disclosed in the Japanese Laid-Open patent No. 3(1991)-194701 conducts reciprocating recording with a drum at a rotary speed two times or more the rotary speed for normal recording or reproduction, thus causing the complexity of circuitry when the VTR is assembled as a standard VTR.
Both VTRs are capable of recording video signals of full field, however, do not provide a time lapse recording function.
SUMMARY OF THE INVENTION
A purpose of the present invention is to provide an apparatus capable of continuous reciprocating recording with a function of time-lapse recording.
The present invention provides an apparatus comprising a rotary drum on which at least a first and a second rotary magnetic head are mounted with 180 degree-symmetry with respect to a center shaft of the rotary drum, the first rotary magnetic head having a magnetic gap set with an azimuth angle of 90 degrees or less in a clockwise direction with respect to a track width direction on a magnetic tape on which at least a video signal is to be recorded, and the second rotary magnetic head having a magnetic gap set with an azimuth angle of 90 degrees or less in an anticlockwise direction with respect to the track width direction; and a controller for sequentially and selectively recording at least the video signal on the magnetic tape to repeatedly record, by the first rotary magnetic head, first tracks each corresponding to one picture video signal on the magnetic tape while continuously travelling at a speed V
in a first direction, and to repeatedly record, by the second rotary magnetic head, second tracks each corresponding to one picture video signal on the magnetic tape so that one of the second tracks is sandwiched between the two of the first tracks while the magnetic tape is continuously travelling at the speed V
in a second direction opposite to the first direction, where V is a predetermined speed and n is a natural number.
Further, the present invention provides an apparatus comprising: a rotary drum on which at least a first and a second rotary magnetic head are mounted with 180 degree-symmetry with respect to a center shaft of the rotary drum, the first rotary magnetic head having a magnetic gap set with an azimuth angle of 90 degrees or less in a clockwise direction with respect to a track width direction on a magnetic tape on which at least a video signal is to be recorded, and the second rotary magnetic head having a magnetic gap set with an azimuth angle of 90 degrees or less in an anticlockwise direction with respect to the track width direction; and a controller for sequentially and selectively recording at least a video signal on the magnetic tape to repeatedly record, by the first rotary magnetic head, a track of the video signal on the magnetic tape while stopped after intermittent transfer by a distance corresponding to a two track-width in a first direction, and to repeatedly record, by the second rotary magnetic head, another track of the video signal on the magnetic tape while stopped after intermittent transfer by the distance in a second direction opposite to the first direction.
REFERENCES:
patent: 3663766 (1972-05-01), Goto
patent: 4796104 (1989-01-01), Ito et al.
patent: 4829389 (1989-05-01), Fukuda
patent: 5680499 (1997-10-01), Choi
patent: 0 671 722 (1995-09-01), None
patent: 50-85316 (1975-07-01), None
patent: 59-104706 (1984-06-01), None
patent: 60-47103 (1985-04-01), None
patent: 60-61905 (1985-04-01), None
patent: 63-224005 (1988-09-01), None
patent: 2-42602 (1990-02-01), None
patent: 3-194701 (1991-08-01), None
patent: 5-167977 (1993-07-01), None
patent: 8-235551 (1996-09-01), None
patent: 9-138924 (1997-05-01), None
patent: 9-161201 (1997-06-01), None
Hirohata Naoto
Nishima Ryou
Anderson Kill & Olick P.C.
Nguyen Huy
Victor Company of Japan Ltd.
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