Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-12-02
2001-02-20
Nguyen, Huy (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06192185
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for recording an information signal, such as a digital video signal, so as to produce slant tracks on a magnetic record carrier, and for recording a control (CTL) signal so as to produce a longitudinal CTL track on said record carrier, the apparatus comprising:
input means for receiving the information signal,
first writing means comprising a plurality of at least a first and a second write heads located on a rotatable head drum, for writing the information signal on said record carrier so as to produce slant tracks on the record carrier, the first and second write head having a gap with a first azimuth angle and a second azimuth angle, respectively,
generator means for generating a CTL signal with a specific frequency, and
second writing means having a CTL write head for writing the CTL signal on said record carrier so as to produce said longitudinal track, wherein, in a first recording mode, the first writing means is adapted to write, by said at least first and second write head and during each revolution of the head drum, a portion of the information signal so as to produce tracks of information during each revolution of said head drum on said record carrier, said specific frequency of said CTL signal being such that the second writing means is adapted to write one edge of a first type in said CTL signal in said CTL track during each revolution of said head drum, the apparatus further comprising:
transport means for transporting the record carrier with a predetermined first speed in said first recording mode, and
drive means for rotating said head drum with a predetermined rotational velocity in said first recording mode.
The invention also relates to an apparatus for reproducing said information signal, recorded in either said first or a second recording mode, as well as to a recording method and to a record carrier.
2. Description of the Related Art
A recording apparatus as defined in the opening paragraph is well known in the art as a helical scan video recorded. Reference is made in this respect to European Patent Application EP-A 346,973, corresponding to U.S. Pat. Nos. 5,412,515 and 5,495,369. The first recording mode can be considered as a recording mode at a nominal record carrier speed. A corresponding reproduction apparatus will be capable of reproducing the information recorded by the known recording apparatus in a first reproduction mode, at the same nominal record carrier speed.
SUMMARY OF THE INVENTION
The invention aims at providing a recording apparatus which enables the first recording mode defined above, as well as a long play recording mode, that is: a recording mode in which the record carrier speed is lower than the nominal record carrier speed defined above. Further, the invention aims at providing a reproduction apparatus which enables the first reproduction mode defined above, as well as a long play reproduction mode, that is: a reproduction mode in which the record carrier speed is the same as the record carrier speed in the second recording mode.
The recording apparatus in accordance with the invention is characterized in that in a second recording mode, the first writing means is adapted to write, by said first write head during each n-th revolution of the head drum, a portion of said information signal so as to produce slant tracks of information during said each n-th revolution of said head drum on said record carrier, the transport means being adapted to transport the record carrier with a second speed which substantially equals the first speed divided by n, in said second recording mode, the drive means being adapted to rotate said head drum with substantially said same predetermined rotational velocity in said second recording mode, the generator means being further adapted to generate said CTL signal with said same predetermined frequency in said second recording mode, and the second writing means being further adapted to write the CTL signal of said predetermined frequency so as to produce said longitudinal track in said second recording mode, and that n is an integer larger than 1.
The reproduction apparatus in accordance with the invention is characterized in that in said second reproduction mode, the first reading means is adapted to read, by said first read head, during each n-th revolution of the head drum, a portion of said recorded information from a track on said record carrier, the transport means being adapted to transport the record carrier with a second speed which substantially equals the first speed divided by n, in said second reproduction mode, and that n is an integer larger than 1, the drive means being adapted to rotate said head drum with said same predetermined rotational velocity in said second reproduction mode, the apparatus further being provided with detection means for detecting, in said second reproduction mode, the signal level of the recorded information read by said first read head during each revolution of the head drum, for determining that one revolution in each group of n revolutions of the head drum that leads to the highest signal level of the recorded information read the first read head and generating a control signal in response thereto, the signal processing means being adapted to process the recorded information read by said first read head during that one revolution of each group of n revolutions indicated by said control signal.
The invention is based on the recognition to use a CTL signal with a frequency that is the same for both recording modes. This has the advantage that in both modes the signal electronics can function in the same frequency range. This feature, however, results in too many CTL edges recorded in the CTL track for a proper reproduction in the second reproduction mode. This is overcome by detecting the envelope amplitude of the signal reproduced in the second reproduction mode and by shifting the processing cycle during reproduction in time, such that those bursts of information read from the record carrier having the highest amplitude are used for processing so as to obtain a replica of the information signal originally recorded.
It should be noted that International Patent Application WO 96/13831, corresponding to U.S. patent application Ser. No. 08/977,259, filed Nov. 24, 1997, discloses an analog video recorder capable of recording an analog video signal in either a first or a second recording mode. The first recording mode is the well-known recording mode in which the record carrier is transported with the nominal recording speed, and the second recording mode is a recording mode with a reduced record carrier speed. During the second recording mode, both heads function in the same way as in the first recording mode. Further, the document discloses a digital video recorder provided with four write heads for writing the digital video information. Only a recording mode is described in which the record carrier speed is slightly higher than the nominal record carrier speed defined above. The digital video recorder produces a record carrier having subsequent groups of four tracks recorded on it by the four heads and having different azimuths. Three rising edges in the CTL signal each time correspond to a group of four tracks.
REFERENCES:
patent: 5335116 (1994-08-01), Onishi et al.
patent: 5412515 (1995-05-01), Rijckaert et al.
patent: 5495369 (1996-02-01), Rijckaert et al.
patent: 5594596 (1997-01-01), Kawakami et al.
patent: 96/13831 (1996-05-01), None
Looykens Marinus A. H.
Rijckaert Albert M. A.
Goodman Edward W.
Nguyen Huy
U.S. Philips Corporation
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