Dynamic magnetic information storage or retrieval – Recording or reproducing plural information signals on the...
Reexamination Certificate
1998-04-15
2001-02-20
Sniezek, Andrew L. (Department: 2753)
Dynamic magnetic information storage or retrieval
Recording or reproducing plural information signals on the...
C360S027000, C360S070000, C386S349000, C386S349000
Reexamination Certificate
active
06191900
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a digital signal recording and reproducing apparatus. Also, this invention relates to a recording medium.
2. Description of the Related Art
There is a known digital VTR (video tape recorder) including a rotary head via which a digital signal representative of information is recorded on a magnetic tape. During playback, the digital signal is reproduced from the magnetic tape via the rotary head. The speed of the magnetic tape and the rotational speed of the rotary head which occur during normal-speed playback are equal to those occurring in the recording mode of operation of the digital VTR.
In such a digital VTR, during the recording mode of operation, a magnetic tape is driven at a predetermined tape speed while a rotary head is rotated at a predetermined head speed. The predetermined tape speed and the predetermined head speed are fixed. Thus, the predetermined tape speed and the predetermined head speed can not be changed. Any special signal representing the speed of the magnetic tape and the rotational speed of the rotary head is not recorded on the magnetic tape. During a normal-speed playback mode of operation of the digital VTR, the magnetic tape is driven at the predetermined tape speed and the rotary head is rotated at the predetermined head speed as in the recording mode of operation.
A known analog VTR can selectively operate in either a normal time mode or a long time mode. The long time mode of operation can continue to record an information-representing signal on a magnetic tape for an interval equal to three times an interval available in the normal time mode of operation. In the analog VTR, during the recording of an information-representing signal on the magnetic tape, a control pulse signal is recorded on a control track extending along a longitudinal direction of the magnetic tape. The recorded control pulse signal has a period depending on whether the signal recording is implemented by the normal time mode or the long time mode. During playback, the analog VTR reproduces a control pulse signal, and decides whether an information-representing signal is of the type recorded by the normal time mode or the long time mode.
SUMMARY OF THE INVENTION
It is a first object of this invention to provide an apparatus for recording a digital signal at a variable data rate (a variable signal recording rate), and for reproducing the recorded digital signal.
It is a second object of this invention to provide a recording medium on which a digital signal is recorded by such an apparatus.
A first aspect of this invention provides a digital signal recording and reproducing apparatus comprising a plurality of heads; first means for recording a digital signal containing an information signal on a recording medium via heads among the heads while sequentially forming tracks on the recording medium; second means for reproducing the digital signal from the recording medium via heads among the heads; a reproduced signal processing circuit for processing the digital signal reproduced by the second means at a changeable data processing rate to recover the information signal from the digital signal reproduced by the second means; third means for, during the recording by the first means, setting a speed of the heads, a speed of the recording medium, a data rate of the recording, and a number of used heads to changeable values respectively; fourth means for allowing the first means to record the digital signal and a mode signal representative of the values set by the third means on the tracks on the recording medium at approximately a predetermined constant recording wavelength; fifth means for, at a start of the reproducing by the second means, setting the speed of the heads, the speed of the recording medium, the data processing rate, and the number of used heads to predetermined initial values respectively; sixth means for detecting the mode signal in the digital signal reproduced by the second means; seventh means for, after the start of the reproducing by the second means, substantially equalizing the speed of the heads, the speed of the recording medium, and the number of used heads to the respective corresponding values represented by the mode signal detected by the sixth means; and eighth means for, after the start of the reproducing by the second means, controlling the data processing rate at a value substantially corresponding to the value of the data rate of the recording which is represented by the mode signal detected by the sixth means.
A second aspect of this invention provides a digital signal recording and reproducing apparatus comprising a plurality of rotatable heads; first means for recording a digital signal containing an information signal on a recording tape via heads among the heads while sequentially forming slant tracks on the recording tape; second means for reproducing the digital signal from the recording tape via heads among the heads; a reproduced signal processing circuit for processing the digital signal reproduced by the second means at a changeable data processing rate to recover the information signal from the digital signal reproduced by the second means; third means for, during the recording by the first means, setting a rotational speed of the heads, a feed speed of the recording tape, a data rate of the recording, and a number of used heads to changeable values respectively; fourth means for allowing the first means to record the digital signal and a mode signal representative of the values set by the third means on the slant tracks on the recording tape at approximately a predetermined constant recording wavelength; fifth means for, at a start of the reproducing by the second means, setting the rotational speed of the heads, the feed speed of the recording tape, the data processing rate, and the number of used heads to predetermined initial values respectively; sixth means for detecting the mode signal in the digital signal reproduced by the second means; seventh means for, after the start of the reproducing by the second means, substantially equalizing the rotational speed of the heads, the feed speed of the recording tape, and the number of used heads to the respective corresponding values represented by the mode signal detected by the sixth means; and eighth means for, after the start of the reproducing by the second means, controlling the data processing rate at a value substantially corresponding to the value of the data rate of the recording which is represented by the mode signal detected by the sixth means.
A third aspect of this invention is based on the second aspect thereof, and provides a digital signal recording and reproducing apparatus wherein a value “d/(r•n)” remains approximately constant during the recording by the first means, and “d”, “r”, and “n” denote the rotational speed of the heads, the feed speed of the recording tape, and the number of used heads respectively.
A fourth aspect of this invention is based on the second aspect thereof, and provides a digital signal recording and reproducing apparatus wherein the reproduced signal processing circuit comprises 1) a waveform equalizer for subjecting the digital signal reproduced by the second means to a waveform equalization process in response to a sampling clock signal determining the data processing rate, 2) a detector for converting an output signal of the waveform equalizer into a binary signal, 3) a phase locked loop circuit for reproducing a clock signal from an output signal of the detector, and 4) a discriminator for generating reproduced data from the output signal of the detector in response to the clock signal reproduced by the phase locked loop circuit, and wherein the eighth means comprises a sampling clock generation circuit for controlling a frequency of the sampling clock signal in response to the value of the data rate of the recording which is represented by the mode signal detected by the sixth means.
A fifth aspect of this invention is based on the second aspect thereof, a
Higurashi Seiji
Zenno Yoichi
Pollock Vande Sande & Amernick
Sniezek Andrew L.
Victor Company of Japan Ltd.
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