Patent EP0094207A2 successfully refreshed from Google Patents.
EP0094207A2
Expired / Lapsed
EP
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Video tape recorder having uninterrupted tracking control during insert edit mode
Assignee: Panasonic Holdings Corp
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Filing: 1983-05-05
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Granted: —
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Expires: 2003-05-05
Abstract
Abstract In a video tape recorder of the helical scan type having a pair of heads mounted on diametrically opposite positions of a rotary cylinder, a pilot signal is recorded through the heads on the same track with video signal during recording and edit modes. During «insert» edit modes, the video heads are alternately switched between playback and recording modes in synchronism with each half revolution of the cylinder. A tape is wound over an arcuate extent greater than a semicircle of the circumference on the cylinder so that the video heads are simultaneously in contact with the tape at different positions to record a video signal over a major portion of the track and record a pilot signal over the full length of the track. One of the heads is in a recording mode and tracing the major portion of a given track, while the other head is in a playback mode tracing a minor portion of a subsequent track where the prerecorded pilot signal is present. A tracking signal is derived from the prerecorded pilot signal.
Inventors
- 👤 Yasuo Nishitani
- 👤 Osahiko Yano
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 11:06
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/18; G11B15/46; G11B15/467; G11B15/4673; G11B15/4675; G11B15/4676; G11B15/4677; G11B15/4678; G11B15/1808; G11B15/1875; G11B27/00; G11B27/02; G11B27/022; G11B27/029; G11B5/00; G11B5/48; G11B5/58; G11B5/584; G11B5/588; G11B2220/00; G11B2220/90; G11B27/024
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
249 words
A video tape recording and reproducing apparatus comprising a pair of transducer heads (A, B) mounted in diametrically opposite positions of the circumference of a rotary cylinder (1) rotatable about an axis tilted with respect to the direction of motion of a magnetic tape (2) for recording a video signal on and detecting it from parallel tracks inclined obliquely to the length of the tape, said tape being wound on an arcuate extent greater than a semicircle of said cylinder so that when one of said heads is traciang a major portion of a given track the other head is tracing a minor portion of a subsequent track, means (43-52) for generating and recording a different pilot signal on the major portion of each said track simultaneously with said video signal and on the minor portion of a subsequent track, and means (31, 32, 87, 53-64) for deriving a tracking control signal from the pilot signal detected by said transducer heads, characterized by means (3, 26, 27, 83, 84, 19, 20) for initially operating said transducer heads (A, B) in playback mode and subsequently alternating the operating modes of said transducer heads between playback and recording in synchronism with each half revolution of said cylinder to record an insert program along the major portion (63-65) of a track through one of the heads and cause said tracking signal generating means to derive said tracking control signal through the other head from the minor portion (el-e2) of a subsequent track.
Claim 2
Dependent Claim
249 words
A video tape recording and reproducing apparatus comprising a pair of transducer heads (A, B) mounted in diametrically opposite positions of the circumference of a rotary cylinder (1) rotatable about an axis tilted with respect to the direction of motion of a magnetic tape (2) for recording a video signal on and detecting it from parallel tracks inclined obliquely to the length of the tape, said tape being wound on an arcuate extent greater than a semicircle of said cylinder so that when one of said heads is traciang a major portion of a given track the other head is tracing a minor portion of a subsequent track, means (43-52) for generating and recording a different pilot signal on the major portion of each said track simultaneously with said video signal and on the minor portion of a subsequent track, and means (31, 32, 87, 53-64) for deriving a tracking control signal from the pilot signal detected by said transducer heads, characterized by means (3, 26, 27, 83, 84, 19, 20) for initially operating said transducer heads (A, B) in playback mode and subsequently alternating the operating modes of said transducer heads between playback and recording in synchronism with each half revolution of said cylinder to record an insert program along the major portion (63-65) of a track through one of the heads and cause said tracking signal generating means to derive said tracking control signal through the other head from the minor portion (el-e2) of a subsequent track.
Claim 3
Dependent Claim
43 words
An apparatus as claimed in claim 1, characterized in that said tracking signal generating means comprises means (80) for storing said tracking signal derived from said minor portion until said pilot signal is detected from the minor portion of the next adjacent track.
Claim 4
Dependent Claim
156 words
An apparatus as claimed in claim 1 or 2, characterized in that said alternating means comprises: pulse generating means (3) for generating a first and a second series of gating pulses (Al, Bl: All, Bl') having a duration substantially equal to or greater than the period of a half revolution of said cylinder, the gating pulses (Al) of first series occurring alternately with the gating pulses (Bl) of said second series; and means (83, 84, 19, 20) for alterternately causing said first and second transducer heads (A, B) to record the input video signal of an insert program on a major portion (θ3-θ5) of each said track in response to the gating pulses (Al, Bl: Al', Bl') of said first and second series and causing said first and second transducer heads to alternately detect a pilot signal from a minor portion (el, 62) of said track during the interval between succesive ones of said gating pulses.
Claim 5
Dependent Claim
166 words
An apparatus as claimed in claim 3, characterized in that the duration of said gating pulses (Al, Bl) of each of said first and second series substantially equals the field interval (θ4) of said video signal, in that said pulse generating means (3) is arranged to further generate a third and a fourth series of gating pulses (A2, B2) having a duration much smaller than said field interval, the gating pulses of the third and fourth series occurring at mutually exclusive times and continuously with the gating pulses (Al, Bl) of said first and second series respectively, in that means (22-25) is provided for converting an audio signal into a series of time-compressed digital samples each of which is applied to said first and second transducer heads (A, B) in response to the gating pulses (A2, B2) of said third and fourth series respectively said minor portion during said recording mode, and means (81, 82) is provided for disabling said audio signal during said edit mode.
Claim 6
Dependent Claim
238 words
An apparatus as claimed in claim 3, characterized in that the duration of said gating pulses of each of said first and second series substantially equals the field interval of said video signal plus an extra interval (91 + 62), in that said pulse generating means is arranged to further generate a third and a fourth series of gating pulses (A4, B4) having a duration substantially equal to said extra interval, the gating pulses of the third and fourth series occurring at mutually exclusive times and overlapping with the gating pulses (All, Bl') of said first and second series respectively, and a fifth and a six series of gating pulses (A3', B3') occurring at mutually exclusive times and continuously with the gating pulses (Al', Bl') of said first and second series respectively, and in that the apparatus further includes means (22-25) for converting an audio signal into a series of time-compressed digital samples and appending a preamble code to each digital sample; means (26, 27) for applying said preamble code and each of said dig the video signal over a major portion of the track and the pilot signal over the full length of the track. One of the heads is in a recording mode and tracing the major portion of a given track, while the other head is in a playback mode tracing a minor portion of a subsequent track where the prerecorded pilot signal is present.
Claim 7
Independent Claim
159 words
An apparatus as claimed in claim in any preceding claim, characterized in that said pilot signal generating means comprises means (43-50, 85) for deriving a recurrent series of pilot signals of different frequencies in synchronism with each half revolution of said cylinder from an input video signal and applying said recurrent pilot signals to said transducer heads during said recording and edit modes and deriving said pilot signals from signals detected by said transducer heads during said playback mode, and in that said tracking signal generating means comprises means (53-56) for detecting beat frequencies between a pilot signal recorded on a given track and each of adjacent pilot signals recorded on tracks located on opposite sides of said given track and generating therefrom a pair of beat frequency signals (fH' 3f H ), and means for detecting the difference between said beat frequency signals as an indication of a deviation of said transducer heads laterally from said given track.
Claim 8
Dependent Claim
72 words
An apparatus as claimed in claim 6, characterized in that said beat frequency detecting means comprises a balanced modulator (54) having a first input responsive to pilot signals detected by said transducer heads and a second input responsive to said pilot signals generated by said pilot signal generating means (43-52) and a pair of band-pass filters (55, 56) connected to the output of said balanced modulator to detect said beat frequency signals.
References Cited (Backward Citations)
No citation records indexed.
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