US3629496A
Expired / Lapsed
US
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Encoding of picture signals in photofacsimile
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1969-12-30
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Granted: 1971-12-21
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Expires: 1989-12-30
Abstract
Abstract A method and apparatus for electrically transmitting subject copy such as continuous tone photographs by digitized signals of a character determined by the changes in tone density in different areas of the subject copy. The varying analog signal output of the facsimile scanner is converted into digital signals forming a sequence of short pulses for transmission to the recorder, the digital signals being varied in such a manner as to reproduce the black and the gray shaded areas of the subject copy.
Inventors
- 👤 Kenneth R Mcconnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:05
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4051
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
84 words
Photofacsimile apparatus comprising a scanner for generating analog picture signals representing image density of the subject copy being scanned, and encoding means for digitizing said analog picture signals, said encoding means comprising a. a sawtooth signal generator, b. means for combining said analog signals with the output of said sawtooth generator, c. a slicer for passing only combined signal waves from said combining means above a predetermined level, and d. means for converting said combined signal waves into digital signals occurring at regular intervals.
Claim 2
Dependent Claim
84 words
Photofacsimile apparatus comprising a scanner for generating analog picture signals representing image density of the subject copy being scanned, and encoding means for digitizing said analog picture signals, said encoding means comprising a. a sawtooth signal generator, b. means for combining said analog signals with the output of said sawtooth generator, c. a slicer for passing only combined signal waves from said combining means above a predetermined level, and d. means for converting said combined signal waves into digital signals occurring at regular intervals.
Claim 3
Dependent Claim
63 words
Photofacsimile apparatus according to claim 1, in which said digital signal converting means includes a timing clock for generating sampling pulses and an AND gate responsive to said combined signal waves and said sampling pulses, and the timing of the sampling pulses in such that the phase relation of said pulses to the output of the sawtooth generator varies in a pseudorandom manner.
Claim 4
Dependent Claim
25 words
Photofacsimile apparatus according to claim 2, in which the occurrence of the sampling pulses varies alternately above and below the midpoint of the sawtooth wave.
Claim 5
Dependent Claim
32 words
Photofacsimile apparatus according to claim 3, in which the timing of the sampling pulses in such that the phase relation timing pattern can repeat only after a large number of clock pulses.
Claim 6
Dependent Claim
98 words
Apparatus for electrically transmitting subject copy or images by a coded sequence of digital signals comprising a facsimile scanner for generating analog video signals, means for additively combining a sawtooth wave with said video signals to generate a second signal current in the output thereof, a slicer consisting of two-level threshold means connected to the output of said combining means, and means connected to said slicer for digitizing the resultant video signals, including sampling means, to generate signals in the form of a sequence of pulses varying in accordance with the gray scale variations in the subject copy.
Claim 7
Dependent Claim
98 words
Apparatus for electrically transmitting subject copy or images by a coded sequence of digital signals comprising a facsimile scanner for generating analog video signals, means for additively combining a sawtooth wave with said video signals to generate a second signal current in the output thereof, a slicer consisting of two-level threshold means connected to the output of said combining means, and means connected to said slicer for digitizing the resultant video signals, including sampling means, to generate signals in the form of a sequence of pulses varying in accordance with the gray scale variations in the subject copy.
Claim 8
Dependent Claim
29 words
Apparatus for transmitting subject copy according to claim 5, in which the sawtooth wave is out of phase with the timing intervals or sampling rate of saiD sampling means.
Claim 9
Dependent Claim
28 words
Apparatus for transmitting subject copy according to claim 5, in which the phase of the sawtooth wave varies in a random manner with respect to the sampling rate.
Claim 10
Dependent Claim
106 words
Apparatus for electrically transmitting continuous tone photographs or the like comprising a facsimile scanner for generating analog video signals, means for additively combining a sawtooth wave with said video signals, a biased diode connected to said additive combining means to suppress the modified signal wave below a predetermined level, and analog/digital converting means for digitizing the resultant video signals, said converting means including an AND gate and a source of sampling pulses, said gate having two inputs connected respectively to said diode and said source of sampling pulses to generate binary signals in the form of a sequence of pulses in the output of said gate.
Claim 11
Dependent Claim
106 words
Apparatus for electrically transmitting continuous tone photographs or the like comprising a facsimile scanner for generating analog video signals, means for additively combining a sawtooth wave with said video signals, a biased diode connected to said additive combining means to suppress the modified signal wave below a predetermined level, and analog/digital converting means for digitizing the resultant video signals, said converting means including an AND gate and a source of sampling pulses, said gate having two inputs connected respectively to said diode and said source of sampling pulses to generate binary signals in the form of a sequence of pulses in the output of said gate.
Claim 12
Independent Claim
84 words
The method of facsimile communication comprising the steps of generating analog signals representing subject copy, adding a sawtooth wave of constant amplitude to the analog facsimile signals, suppressing the portion of the resultant signal wave below a predetermined level to produce a two level binary signal wave, sampling the two level binary signal wave at a predetermined bit rate, and generating pulses at the instants of sampling to form a varying sequence of pulses representing the signal level variations of the original analog signals.
Claim 13
Independent Claim
84 words
The method of facsimile communication comprising the steps of generating analog signals representing subject copy, adding a sawtooth wave of constant amplitude to the analog facsimile signals, suppressing the portion of the resultant signal wave below a predetermined level to produce a two level binary signal wave, sampling the two level binary signal wave at a predetermined bit rate, and generating pulses at the instants of sampling to form a varying sequence of pulses representing the signal level variations of the original analog signals.
Claim 14
Dependent Claim
27 words
The method of facsimile communication according to claim 9, in which the frequency of said peaked wave has a predominantly out-of-phase relation to the sampling bit rate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |