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US 4,510,538 AGranted
Magnetic recording apparatus
AssigneeSony Corporation
InventorsSeiji Sato, Koichi Takeuchi
Life of this patent
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AssigneeSony Corporation
InventorsSeiji Sato, Koichi Takeuchi
Estimating the term…
A miniature helical scan video tape recorder (VTR) utilizes a reduced-diameter guide drum, but the video signals recorded thereby onto the tape have a standard track pattern and can be reproduced using a standard VTR having a guide drum of standard diameter D.sub.1. In the miniature VTR, the tape is wrapped for a tape wrap angle .alpha. (e.g., substantially 300 degrees) at a still angle .theta..sub.2, whereas the standard VTR uses a wrap angle of 180.degree. and a still angle of .theta..sub.1. In order to ensure that the miniature VTR achieves the same record track length l'.sub.N and recording angle .theta..sub.0 as the standard VTR, the diameter D.sub.2 of the miniature VTR is selected to satisfy the equation ##EQU1## where f.sub.V is the video field frequency. The still angle .theta..sub.2 satisfies the equation ##EQU2## the video signal to be recorded is given a non-standard horizontal scanning frequency f'.sub.H according to the relation ##EQU3## where f.sub.H is the standard horizontal scanning frequency. The recording head can be provided with two gaps for double-azimuth recording of the video signal.
In helical scan type magnetic recording apparatus having a rotary magnetic head with at least one magnetic gap and disposed on a reduced-size guide drum of a diameter D.sub.2 about which a magnetic tape is wound for a wrapping angle .alpha. for recording of fields of a video signal having a standard vertical synchronizing frequency f.sub.V in slant tracks on the tape arranged at a recording angle .theta..sub.0 with respect to the longitudinal direction of the tape when the tape is advanced at a tape running speed V, with the length of the tracks being l'.sub.N, such that the recorded tape is compatible with standard video playback apparatus having a standard-sized rotary drum of diameter D.sub.1, greater than the diameter D.sub.2, and with the tape being wrapped thereabout for a wrapping angle of substantially 180.degree. and at a still angle of .theta..sub.1 with the video signal reproduced from said tape having said standard vertical synchronizing frequency f.sub.V and a standard horizontal scanning frequency f.sub.H ;
In helical scan type magnetic recording apparatus having a rotary magnetic head, said at least one head including a first recording gap at one predetermined azimuth angle and second recording gap at another, different predetermined azimuth angle, said first and second gaps being separated from one another by a predetermined spacing and used alternately for recording a video signal in alternate slant tracks on a magnetic tape, said at least one head being disposed on a reduced-size guide drum of a diameter D.sub.2 about which said magnetic tape is wound for a wrapping angle .alpha. for recording of fields of said video signal with a vertical synchronizing signal having a standard vertical synchronizing frequency f.sub.V in said slant tracks on the tape arranged at a recording angle .theta..sub.0 with respect to the longitudinal direction of the tape when the tape is advanced at a tape running speed V.sub.1 with the length of the tracks being l'.sub.N such that the recorded tape is compatible with standard video playback apparatus having a standard-size rotary drum of diameter D.sub.1, greater than the diameter D.sub.2 , and with the tape being wrapped thereabout for a wrapping angle of substantially 180.degree. and at a still angle of .theta..sub.1 with the video signal reproduced from said tape having the standard vertical synchronizing frequency f.sub.V and a standard horizontal scanning frequency f.sub.H ;
Dependencies are inferred from the claim text.