Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-07-23
2002-10-01
Chevalier, Robert (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000
Reexamination Certificate
active
06459848
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and an apparatus for magnetically recording an analog signal and a digital signal. This invention also relates to a magnetic recording medium.
2. Description of the Related Art
Japanese published unexamined patent application 61-39784 discloses a method for magnetic recording and reproduction. According to the method in Japanese application 61-39784, a first magnetic head records an analog video signal on a magnetic tape while forming analog video tracks thereon. In addition, a second magnetic head records a digital signal on the analog video tracks. The first and second magnetic heads are different from each other in azimuth angle. A recording current for the digital signal is smaller than that for the analog video signal so that the digital signal will be written into a shallow portion of an analog video recording layer within the magnetic tape.
Japanese application 61-39784 teaches that the analog video signal and the digital signal can be in a common frequency band equal to or higher than a frequency of 1.5 to 2 MHz when the azimuth angles of the first and second magnetic heads are different from each other by 30°.
Japanese published unexamined patent application 6-14343 discloses a video recorder which records a VHS signal (an analog video signal) and a digital video signal on a magnetic tape. In the video recorder of Japanese application 6-14343, a first magnetic head writes the VHS signal into a major layered portion of the magnetic tape. In addition, a second magnetic head writes the digital video signal into a shallow layered portion or an upper layered portion of the magnetic tape. The first and second magnetic heads are different from each other in azimuth angle and gap width. The first magnetic head is composed of a pair of elements having azimuth angles of ±6°. The second magnetic head is composed of a pair of elements having azimuth angles of ±30°. The first magnetic head has a gap width of 0.4 &mgr;m. The second magnetic head has a gap width of 0.2 &mgr;m.
Japanese application 6-14343 indicates that the digital video signal is in a frequency band from about 2.3 MHz to about 12 MHz.
As the lower limit of a common frequency band for a VHS signal and a digital video signal drops, the digital video signal tends to more interfere with down-converted color components of the VHS signal during the reproduction of the two signals from a magnetic tape. Such interference decreases the quality of pictures represented by the reproduced VHS signal.
SUMMARY OF THE INVENTION
It is a first object of this invention to provide an improved method of recording an analog information signal and a digital information signal on a magnetic recording medium.
It is a second object of this invention to provide an improved apparatus for recording an analog information signal and a digital information signal on a magnetic recording medium.
It is a third object of this invention to provide an improved magnetic recording medium.
A first aspect of this invention provides a method of magnetic recording which comprises the steps of alternately using first and second magnetic heads to record an analog video signal on a magnetic recording medium while sequentially forming first tracks on the magnetic recording medium, the magnetic recording medium being fed with respect to a rotary drum at a predetermined speed, the magnetic recording medium being wound on an outer circumferential surface of the rotary drum along a part of a helix in a predetermined angular range, the first and second magnetic heads being attached to the rotary drum, the first and second magnetic heads being diametrically opposed to each other, the first and second magnetic heads being in a first predetermined height position with respect to the rotary drum, the first and second magnetic heads having different azimuth angles respectively; and alternately using third and fourth magnetic heads to record a digital video signal on the magnetic recording medium while sequentially forming and writing second tracks over at least portions of the first tracks on the magnetic recording medium, the third and fourth magnetic heads being attached to the rotary drum, the third and fourth magnetic heads being diametrically opposed to each other, the third and fourth magnetic heads being in a second predetermined height position with respect to the rotary drum, the second predetermined height position being different from the first predetermined height position, the third and fourth magnetic heads having different azimuth angles respectively, the azimuth angles of the third and fourth magnetic heads being different from the azimuth angles of the first and second magnetic heads, the digital video signal being in a frequency band wider than a frequency band of the analog video signal, the frequency band of the digital video signal including a frequency band of a frequency converted carrier chrominance signal of the analog video signal, the digital video signal being free from periodicity of its record waveform.
A second aspect of this invention is based on the first aspect thereof, and provides a method wherein a level of the analog video signal recorded by the first and second magnetic heads is greater than a predetermined level which is used in a case where only an analog video signal is recorded.
A third aspect of this invention is based on the first aspect thereof, and provides a method wherein each of the second tracks extends in an area containing a boundary between two neighboring tracks among the first tracks.
A fourth aspect of this invention is based on the first aspect thereof, and provides a method wherein the digital video signal results from subjecting an original video signal to a scramble interleaved NRZI process.
A fifth aspect of this invention provides a magnetic recording apparatus comprising a rotary drum; first and second magnetic heads attached to the rotary drum, the first and second magnetic heads being diametrically opposed to each other, the first and second magnetic heads being in a first predetermined height position with respect to the rotary drum, the first and second magnetic heads having different azimuth angles respectively; first means for generating an analog video signal; second mans for alternately using the first and second magnetic heads to record the analog video signal on a magnetic recording medium while sequentially forming first tracks on the magnetic recording medium, the magnetic recording medium being fed with respect to the rotary drum at a predetermined speed, the magnetic recording medium being wound on an outer circumferential surface of the rotary drum along a part of a helix in a predetermined angular range; third and fourth magnetic heads attached to the rotary drum, the third and fourth magnetic heads being diametrically opposed to each other, the third and fourth magnetic heads being in a second predetermined height position with respect to the rotary drum, the second predetermined height position being different from the first predetermined height position, the third and fourth magnetic heads having different azimuth angles respectively, the azimuth angles of the third and fourth magnetic heads being different from the azimuth angles of the first and second magnetic heads; third means for generating a digital video signal being free from periodicity of its waveform and being in a frequency band wider than a frequency band of the analog video signal, the frequency band of the digital video signal including a frequency band of a frequency converted carrier chrominance signal of the analog video signal; and fourth means for alternately using the third and fourth magnetic heads to record the digital video signal on the magnetic recording medium while sequentially forming and writing second tracks over the first tracks on the magnetic recording medium.
A sixth aspect of this invention is based on the fifth aspect thereof, and provides a magnetic recording apparatus wherein each of the second trac
Chevalier Robert
Victor Company of Japan Ltd.
Woo Louis
LandOfFree
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