Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1999-04-08
2003-09-16
Boccio, Vincent (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000, C360S022000, C360S064000
Reexamination Certificate
active
06621981
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to recording and reproducing apparatus for recording video signals on magnetic tapes and reproducing the recorded video signals, and also reproducing apparatus for reproducing video signals recorded on magnetic tapes.
Particularly, this invention relates to reproduction at travel speeds of magnetic tape that are different from travel speeds at which signals have been recorded. This reproduction is referred to as variable speed reproduction hereinafter.
Digital video tape recorders (VTR) according to DV or DVC standards have already been on the market. The DV standards offer the standard mode and another mode. The former mode is referred to as SP mode in which video signals are recorded on and reproduced from magnetic tapes at the standard travel speed VSP, 18.8 mm/sec., and the data rate of about 25 Mbps (Mega-bit per sec.). The latter mode is referred to as EP mode in which video signals are recorded on and reproduced from magnetic tapes having a track width the same as that for SP mode, at the travel speed that is half the standard speed VSP, and the data rate that is also half the rate for SP mode.
In recording NTSC signals of 525 scanning per 60 sec., one frame video signals are recorded on magnetic tapes so that each frame is divided into ten tracks in SP mode, whereas it is divided into five tracks in EP mode.
Video tape recorders capable of recording and reproduction in SP mode are provided with a speed coefficient, for example, “×9.5” for variable speed reproduction. This means the tape speed is 9.5 times faster than the standard speed VSP. Reproduction at tape speeds obtained by multiplying tape speeds for recording by integers results in reproduction of only a portion of a frame video signal that has been recorded on magnetic tapes so that the signal has been divided into ten tracks, and hence no fine image reproduction.
However, it has not been researched what tape speed is available for reproducing fine images by variable speed reproduction for VTRs capable of recording and reproduction in EP mode.
SP mode recording requires two magnetic heads (referred to as a channel A head and a channel B head hereinafter) having different gap azimuth angles and being arranged on a rotary drum so that they are spaced 180 degrees apart from each other.
On the contrary, EP mode recording with the channel A and B heads for SP mode cannot achieve recorded patterns in accordance with the standards. EP mode recording therefore employs a channel A head and a channel B′ head having the same gap azimuth angle as that of the channel B head but being provided at a different location on the rotary drum. However, it has also not been researched whether fine images can be reproduced by such EP mode recording.
SUMMARY OF THE INVENTION
A purpose of the present invention is to provide a video signal recording and reproducing apparatus and also a reproducing apparatus capable of variable speed reproduction of fine images.
Another purpose of the present invention is to provide a video signal recording and reproducing apparatus and also a reproducing apparatus having plurality of magnetic heads and being capable of variable speed reproduction of fine images by switching the magnetic heads.
The present invention provides an apparatus for recording and reproducing a video signal to and from a magnetic tape. The apparatus includes a controller that selectively controls recording of each frame signal of the video signal in such a way that the frame signal is divided into N (N being a integer of two or more) slant tracks on the magnetic tape at a standard tape speed in a standard mode, the frame signal is divided into N/2 slant tracks at a tape speed ½ of the standard speed in ½ speed mode, or the frame signal is divided into N/2 slant tracks at a tape speed ⅓ of the standard speed in ⅓ speed mode. The controller further controls reproduction in such a way that the frame signal is reproduced at a tape speed n (n being a speed coefficient and n≠1) times the tape speed at which the frame signal has been recorded in at least either the ½ or the ⅓ speed mode. The speed coefficient n is set to a value included in a predetermined range or given by at least either an equation (1) or (2):
n=N
(2
m
+1)/(2
i
−1)±2/(2
i
−1) (1)
n=Nm/i
±1
/i
(2)
where a variable i is an integer from 1 to 10, and a variable m is an integer.
Furthermore, the present invention provides an apparatus for recording and reproducing a video signal to and from a magnetic tape. The apparatus includes a first magnetic head and a second magnetic head having different gap azimuth angles and being spaced 180 degrees apart from each other on a rotary head, and a third magnetic head having the same gap azimuth angle as the gap azimuth angle of the second magnetic head and having a specific relative positional relationship with the first magnetic head on the rotary head. The apparatus also includes a controller that selectively controls recording of each frame signal of the video signal in such a way that the frame signal is divided into N (N being a integer of two or more) slant tracks on the magnetic tape by the first and second magnetic heads at a standard tape speed in a standard mode, the frame signal is divided into N/2 slant tracks by the first and third magnetic heads at a tape speed ½ of the standard speed in ½ speed mode, or the frame signal is divided into N/2 slant tracks by the first and third magnetic heads at a tape speed ⅓ of the standard speed in ⅓ speed mode. The controller further controls reproduction in such a way that the frame signal is reproduced by the first and second magnetic heads at a tape speed different from the tape speed at which the frame signal has been recorded in at least either the ½ or the ⅓ speed mode.
Furthermore, the present invention provides an apparatus for recording and reproducing a video signal to and from a magnetic tape. The apparatus includes a first magnetic head and a second magnetic head having different gap azimuth angles and being spaced 180 degrees apart from each other on a rotary head, and a third magnetic head having the same gap azimuth angle as the gap azimuth angle of the second magnetic head and having a specific relative positional relationship with the first magnetic head on the rotary head. The apparatus also includes a controller that selectively controls recording of each frame signal of the video signal in such a way that the frame signal is divided into N (N being a integer of two or more) slant tracks on the magnetic tape by the first and second magnetic heads at a standard tape speed in a standard mode, the frame signal is divided into N/2 slant tracks by the first and third magnetic heads at a tape speed ½ of the standard speed in ½ speed mode, or the frame signal is divided into N/2 slant tracks by the first and third magnetic heads at a tape speed ⅓ of the standard speed in ⅓ speed mode. The controller further controls reproduction in such a way that the frame signal is reproduced by one of or two of the first, the second and the third magnetic heads at a tape speed n (n being a speed coefficient and n≠1) times the tape speed at which the frame signal has been recorded in at least either the ½ or the ⅓ speed mode. The speed coefficient n is set to a value included in a predetermined range or given by an equation n=Nm/i±1/i where a variable i is an integer from 1 to 10, and variable m is an integer.
Furthermore, the present invention provides an apparatus for reproducing a video signal from a magnetic tape. The apparatus includes a controller that controls reproduction of each frame signal of the video signal that has been recorded in such a way that the frame signal is divided into N (N being a integer of two or more) slant tracks on the magnetic tape at a standard tape speed in a standard mode
Boccio Vincent
Fletcher James A
Jacobson & Holman PLLC
Victor Company of Japan Ltd.
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