US3920901A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Generator used for time synchronization in video-telephone
Assignee: Wachovia Bank NA
•
Filing: 1974-05-07
•
Granted: 1975-11-18
•
Expires: 1994-05-07
Abstract
Abstract A timing generator is disclosed that is particularly adapted for use in video-telephones for synchronization of control signals to a device which forms a subscriber image. The synchronization is performed by the division of a crystal controlled oscillator frequency by first and second counting means. The first counting means generates the basic horizontal scan rate and the second counting means generates the basic vertical scan rate. Each counting means initiates a plurality of signals, synchronously with the oscillator frequency between the two basic scan rates, which are used to set or reset a plurality of bistable multivibrators and thereby generate the synchronous control signals. In a first embodiment, generally available MSI circuit packages are used to implement the teachings of the invention. In a second embodiment both counting means and the plurality of bistable multivibrators are produced by MSI or LSI circuit techniques allowing the entire generator to be formed into three integrated circuit packages.
Inventors
- 👤 Michael A Boehly
- 👤 Uno Randmere
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:45
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/14; H04N7/141; H04N7/147
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
166 words
A synchronous signal generator for use in video-telephone systems; said generator comprising: oscillator means including an output for generating signals having a stable first frequency of pulses; first binary counting means, connected to the output of said oscillator means, for counting said first frequency of pulses and producing a first count of pulses; second binary counting means, connected to the output of said oscillator means and to an intermediate output of said first counting means, for counting said first frequency of pulses and producing a second count of pulses; decoding means connected to said first and second counting means for providing output signals at selected integral counts of said first frequency of pulses; and signal means connected to at least one output of said decoding means for generating at least one control signal synchronously with said output signals, said first and second counting means cooperating to produce at least third and fourth counts of pulses which are intermediate said first and second counts of pulses, respectively.
Claim 2
Dependent Claim
166 words
A synchronous signal generator for use in video-telephone systems; said generator comprising: oscillator means including an output for generating signals having a stable first frequency of pulses; first binary counting means, connected to the output of said oscillator means, for counting said first frequency of pulses and producing a first count of pulses; second binary counting means, connected to the output of said oscillator means and to an intermediate output of said first counting means, for counting said first frequency of pulses and producing a second count of pulses; decoding means connected to said first and second counting means for providing output signals at selected integral counts of said first frequency of pulses; and signal means connected to at least one output of said decoding means for generating at least one control signal synchronously with said output signals, said first and second counting means cooperating to produce at least third and fourth counts of pulses which are intermediate said first and second counts of pulses, respectively.
Claim 3
Dependent Claim
28 words
A signal generator for video-telephone systems as defined in claim 1 wherein: said first count of pulses is equal to the horizontal line scan rate of said systems.
Claim 4
Dependent Claim
28 words
A signal generator for video-telephone systems as defined in claim 1 wherein: said second count of pulses is equal to the vertical field scan rate of said systems.
Claim 5
Dependent Claim
70 words
A signal generator for video-telephone systems as defined in claim 3 wherein: said intermediate output of the first counting means produces a count of pulses equal to one quarter said first count of pulses whereby said second counting means counts in increments of one-half of the horizontal line scan rate and; wherein said second count is an odd multiple of horizontal half lines to provide for interlacing adjacent vertical fields.
Claim 6
Dependent Claim
121 words
A signal generator for video-telephone systems as defined in claim 4 wherein said first counting means includes: a first four bit binary ripple counter, connected to said oscillator means, for dividing said first frequency of pulses by a factor of sixteen; and a second four bit binary ripple counter, connected to said oscillator and enabled by a carry output of said first binary counter, for dividing said first frequency of pulses by a factor of two hundred fifty-six; wherein said first count is an integral count evenly divisible by four of said first and second binary counters and said first counting means includes a first preset signal means for clearing said second binary counters upon the obtainment of said first count.
Claim 7
Dependent Claim
161 words
A signal generator for video-telephone systems as defined in claim 5 wherein said second counting means includes: a third four bit binary ripple counter, connected to said oscillator means, for dividing said intermediate count of pulses by a factor of sixteen, a fourth four bit binary ripple counter connected to said oscillator means and enabled by a carry output from said third binary counter for dividing said intermediate count by a factor of two raised to the eighth power and a fifth four bit binary ripple counter connected to said oscillator means and enabled by a carry output from said fourth binary counter, for dividing said intermediate count by a factor of two raised to the twelfth power wherein said second count is an integral count of said third, fourth, and fifth binary counters and said second counting means includes a second preset signal means for clearing said third, fourth and fifth binary counters upon the obtainment of said second count.
Claim 8
Dependent Claim
49 words
A signal generator for video-telephone systems as defined in claim 6 wherein said first and second counting means include resetting means for resetting said first, second, third, fourth and fifth binary counters upon a count larger than said second count and independently of said first and second preset signals.
Claim 9
Dependent Claim
49 words
A signal generator for video-telephone systems aS defined in claim 7 wherein said oscillator means are crystal controlled and said first frequency of pulses is one thousand and 24 KHz, and wherein each pulse width of said first frequency is substantially smaller than the resolution between said control signals.
Claim 10
Dependent Claim
60 words
A signal generator for video-telephone systems as defined in claim 8 wherein said signal means includes a a plurality of R-S multivibrators having a high frequency group of said multivibrators for generating horizontal control signals, a lower frequency group of said multivibrators for generating vertical control signals, and combinational means for producing composites of said horizontal and vertical control signals.
Claim 11
Dependent Claim
33 words
A signal generator for video-telephone systems as defined in claim 9 wherein said combinational means includes privacy means for generating a privacy bar signal allowing audio communication in said systems without video transmission.
References Cited (Backward Citations)
US3716795A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |