US3767849A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for playing-back video signals
Assignee: US Philips Corp
•
Filing: 1971-11-22
•
Granted: 1973-10-23
•
Expires: 1991-11-22
Abstract
Abstract A device compensating for fluttering effects due to elongation variation by measuring phase shift at the end of a track change in a helical recording video system. During the track change the output of the control circuit is connected to a first input of a comparison circuit, a second input of which is connected to an output of the auxiliary generator which is designed as a sawtooth generator, the output of the comparison circuit being connected to a pulse generator which produces the missing linesynchronizing pulses in a manner such that these pulses are at least substantially in phase with the line synchronizing pulses of the next track. In the comparison circuit the direct voltage of the control circuit is compared with the amplitude of the sawtooth voltage, and when the two voltages are equal the pulse source produces a line synchronizing pulse which is at least substantially in phase with the line synchronizing pulses of the next track.
Inventors
- 👤 J Wessels
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:47
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/76; H04N5/91; H04N5/93; H04N5/932
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
227 words
In a video system, and apparatus compensating for loss of synchronization during track changes, comprising a tape shaped record carrier having video signals and synchronization pulses recorded thereon in transverse tracks, said carrier being helically wound about a drum, said drum including a slot and at least one playback member rotating in said slot at right angles to the axis of said drum, said member scanning said carrier and transducing said video signals and line synchronizing pulses continuously except during track changes, a voltage controllable frequency generator, a phase comparison circuit, said phase comparison circuit receiving said line synchronization pulses and signals from said frequency generator, said phase comparison circuit generating a phase comparison voltage output, said phase comparison voltage output being coupled to said frequency generator to render generation frequency equal to frequency of said line synchronization pulse, first means responsive to each first line synchronization pulse of successive tracks and coupled to the output of said phase comparator for clamping said voltage output to a clamped signal level for each successive line synchronizing pulse received thereby, second means responsive to said track changes for decoupling from said phase comparison circuit to said first means during said track changes, and third means coupled to the frequency generator and said second means for deriving continuous compensated line synchronization pulses at a rate determined by said frequency generator.
Claim 2
Dependent Claim
227 words
In a video system, and apparatus compensating for loss of synchronization during track changes, comprising a tape shaped record carrier having video signals and synchronization pulses recorded thereon in transverse tracks, said carrier being helically wound about a drum, said drum including a slot and at least one playback member rotating in said slot at right angles to the axis of said drum, said member scanning said carrier and transducing said video signals and line synchronizing pulses continuously except during track changes, a voltage controllable frequency generator, a phase comparison circuit, said phase comparison circuit receiving said line synchronization pulses and signals from said frequency generator, said phase comparison circuit generating a phase comparison voltage output, said phase comparison voltage output being coupled to said frequency generator to render generation frequency equal to frequency of said line synchronization pulse, first means responsive to each first line synchronization pulse of successive tracks and coupled to the output of said phase comparator for clamping said voltage output to a clamped signal level for each successive line synchronizing pulse received thereby, second means responsive to said track changes for decoupling from said phase comparison circuit to said first means during said track changes, and third means coupled to the frequency generator and said second means for deriving continuous compensated line synchronization pulses at a rate determined by said frequency generator.
Claim 3
Dependent Claim
86 words
The combination of claim 1, wherein said third means includes a comparator having a first input coupled to an output of said frequency generator and a second input coupled to said second means, said second means supplying said phase comparison output signal to said comparator during scan of a track, and said changed signal level to said comparator between track scans, the output of said comparator being coupled to a pulse generator, said pulse generator responsive to said comparator for generating said compensated line synchronization pulses.
Claim 4
Dependent Claim
60 words
The combination of claim 1, wherein said second means is a switch, said switch having a first position for coupling said phase comparison output signal to said third means, and a second position for applying said clamped signal level to said third means, said second means switching from said first to said second position during an interval between track scans.
Claim 5
Dependent Claim
140 words
Apparatus compensating for missing line sunchronization pulses due to track changes in a video system comprising a phase comparison circuit having a first input receiving line synchronization pulses, a second input coupled to an oscillator, and an output corresponding to a voltage level indicative of said line pulse, clamping means responsive to said output voltage level and each first line synchronization pulse of successive tracks for storing said voltage level for the duration between beginning and end of said track change, means coupled to said oscillator for deriving compensated line synchronized pulses at said oscillator frequency in response to a signal applied thereto, means coupled to said deriving means responsive to an interval between track changes for applying said clamped voltage level to said deriving means, and alternately applying said output voltage level to said deriving means during scan intervals.
Claim 6
Dependent Claim
140 words
Apparatus compensating for missing line sunchronization pulses due to track changes in a video system comprising a phase comparison circuit having a first input receiving line synchronization pulses, a second input coupled to an oscillator, and an output corresponding to a voltage level indicative of said line pulse, clamping means responsive to said output voltage level and each first line synchronization pulse of successive tracks for storing said voltage level for the duration between beginning and end of said track change, means coupled to said oscillator for deriving compensated line synchronized pulses at said oscillator frequency in response to a signal applied thereto, means coupled to said deriving means responsive to an interval between track changes for applying said clamped voltage level to said deriving means, and alternately applying said output voltage level to said deriving means during scan intervals.
References Cited (Backward Citations)
US3573359A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |