US3757041A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Television special effects control pulsegenerating apparatus
Assignee: RCA Corp
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Filing: 1971-05-28
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Granted: 1973-09-04
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Expires: 1991-05-28
Abstract
Abstract A digital frequency divider produces a plurality of divisional frequency pulses from clock pulses having a multiple of a camera scanning rate for conversion by a digital-to-analogue converter into a ramp type sawtooth-shaped timing wave at a frequency related to the camera scanning rate. An up-down type of digital frequency divider produces a triangle type sawtooth-shaped timing wave having the camera scanning rate frequency. The ramp type timing wave is multiplied by itself to produce a parabola type timing wave having a camera scanning rate frequency. Any of the timing waves is combined with variable direct current to generate pulses by which to control the transfer from the video signals of one camera to the video signals of another camera to produce composite video signals representative of selected parts of two scenes.
Inventors
- 👤 L Thorpe
- 👤 J Killough
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 00:39
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/222; H04N5/262; H04N5/272; H04N5/275; H03; H03K; H03K4/00; H03K4/02; H03K4/026; H03K4/04; H03K6/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
234 words
In a special effects generator for a television system having at least two signal sources for developing two sets of video signals respectively representative of two scenes which are scanned at horizontal and vertical rates, apparatus for generating control pulses by which to transfer selected portions of said two sets of video signals to an output circuit in which to produce composite video signals representative of parts of said two scenes, said pulse-generating apparatus comprising: a clock pulse generator producing output pulses having a frequency at a multiple of one of said scanning rates; wave-producing means including a digital frequency divider coupled to said clock pulse generator to provide a plurality of different divisional frequency pulses therefrom and a digitalto-analogue converter responsive to said different frequency pulses to develop a timing wave having a frequency related to said one scanning rate by the factor N/2 where N is an integer equal to 1 or 2; a first digital comparator coupled to receive said timing wave from said wave-producing means of a first one of its inputs; and a source of direct current coupled to said first comparator at a second one of its inputs for combination with said timing wave to produce said control pulses in the output of said first comparator in accordance with which magnitude of said timing wave and said direct current is the greater at any one instant of time.
Claim 2
Dependent Claim
234 words
In a special effects generator for a television system having at least two signal sources for developing two sets of video signals respectively representative of two scenes which are scanned at horizontal and vertical rates, apparatus for generating control pulses by which to transfer selected portions of said two sets of video signals to an output circuit in which to produce composite video signals representative of parts of said two scenes, said pulse-generating apparatus comprising: a clock pulse generator producing output pulses having a frequency at a multiple of one of said scanning rates; wave-producing means including a digital frequency divider coupled to said clock pulse generator to provide a plurality of different divisional frequency pulses therefrom and a digitalto-analogue converter responsive to said different frequency pulses to develop a timing wave having a frequency related to said one scanning rate by the factor N/2 where N is an integer equal to 1 or 2; a first digital comparator coupled to receive said timing wave from said wave-producing means of a first one of its inputs; and a source of direct current coupled to said first comparator at a second one of its inputs for combination with said timing wave to produce said control pulses in the output of said first comparator in accordance with which magnitude of said timing wave and said direct current is the greater at any one instant of time.
Claim 3
Dependent Claim
30 words
Pulse-generating apparatus as defined in claim 1 wherein: said direct current coupled to said first comparator is adjustable in magnitude, whereby to vary the effective timing of said control pulses.
Claim 4
Dependent Claim
81 words
Pulse-generating apparatus as defined in claim 2 wherein: said wave-producing means also includes, a second digital comparator coupled to compare the phase of one of the outputs of said frequency divider with a signal corresponding to said one scanning rate to develop a direct current signal indicative of the phase relationship existing therebetween, and means impressing said direct current signal upon said clock pulse generator to maintain an accurate phase relationship of said timing wave relative to said one scanning rate.
Claim 5
Dependent Claim
64 words
Pulse-generating apparatus as defined in claim 3 wherein: said wave-producing means is operative for developing a sawtooth-shaped timing wave and further includes, a digital-to-analogue converter comprising a plurality of resistors individually connected as a network to a plurality of the outputs of said digital frequency divider and commonly coupled to an output circuit in which to produce said timing wave having a sawtooth shape.
Claim 6
Dependent Claim
86 words
Pulse-generating apparatus as defined in claim 4 wherein: the lowest frequency output of said digital frequency divider that is connected to said resistor network is one-half of that of said one scanning rate whereby, said sawtooth-shaped timing wave is a ramp having a frequency equal to one-half of said one scanning rate, a gradual slope in one direction during two successive scanning intervals of said video signal and a steep slope in a second direction during blanking periods between alternate scanning intervals of said video signal.
Claim 7
Dependent Claim
81 words
Pulse-generating apparatus as defined in claim 4 wherein: the lowest frequency output of said digital frequency divider that is connected to said resistor network is the same as that of said one scanning rate whereby, said sawtooth-shaped timing wave has a frequency equal to said one scanning rate, a gradual slope in one direction during a scanning interval of said video signal and a steep slope in a second direction during blanking periods between successive scanning intervals of said video signal.
Claim 8
Dependent Claim
53 words
Pulse-generating apparatus as defined in claim 6 wherein: said wave-producing means additionally includes, an electronic multiplier having two inputs and one output, and means impressing said sawtooth-shaped timing wave upon both inputs of said multiplier to produce a parabola-shaped timing wave of frequency equal to said one scanning rate in said multiplier output.
Claim 9
Dependent Claim
148 words
Pulse-generating apparatus as defined in claim 4, wherein: said frequency divider is a digital up-down counter, and said wave-producing means further includes, two gates coupled between said clock pulse generator and said counter and separately operable to impress pulses from said clock pulse generator upon said counter as up and down pulses respectively, and gate-operating means responsive to outputs of said frequency divider to operate a first one of said gates at the beginning of each wave-producing means operating period and a second one of said gates at the midpoint of each of said operating periods whereby, said sawtooth-shaped timing wave is a triangle having a frequency equal to said one scanning rate, a given slope in one direction during the first half of each of said operating periods and an equal, given slope in a second direction during the second half of each of said operating periods.
Claim 10
Dependent Claim
140 words
Pulse-generating apparatus as defined in claim 8 wherein: said gate-operating means includes, two flip-flop devices each having two inputs and one output, an AND gate coupled between the plurality of outputs of said digital frequency divider and one input of a first one of said flip-flop devices to cause it to produce in its output an operating signal for said first gate at the beginning of each of said wave-producing means operating periods, means coupling the double scanning interval frequency output of said digital frequency divider to one input of a second one of said flip-flop devices to cause it to produce in its output an operating signal for said second gate at the midpoint of each of said operating periods, and means cross-coupling the outputs of each of said flip-flop devices to the other inputs of said respective devices.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |