US3916096A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic screening
Assignee: PRINTING TECHNOLOGIES ASSOCIATES Inc
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Filing: 1974-02-08
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Granted: 1975-10-28
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Expires: 1994-02-08
Abstract
Abstract This invention relates to a method and apparatus for the electronic screening of a graphic image to be reproduced by printing. The density of the graphic image is determined either repetitively or continuously during the generation of each dot which will form a part of the half-tone image when produced, and the dot is modified according to changes in the density. Thus the structure of any half-tone dot may be modified during its construction. Electronic screening processes are also disclosed employing a random number generator to break up repetitive patterns which occur during screening and in which the random number generator produces small dots which are much smaller in size than the normal size of half-tone screen dots and whose distribution in a reproduced half-tone image varies with the density of the graphic image being screened.
Inventors
- 👤 Robert Charles Everett
- 👤 Paul Anthony Beaufor Radcliffe
- 👤 Alfred Henry Robinson
- 👤 Janusz Andrew Veltze
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 01:37
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4055; H04N1/4058
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
123 words
Apparatus for electronic screening of a graphic image to be reproduced by printing and wherein an analogue video signal representing the optical density variations of said graphic image is continuously produced, said apparatus comprising: means for generating a range of sawtooth waveforms, means for accepting said analogue video signal, during the generation of each dot which will form a part of the half tone image when reproduced, as a series of successive scans, means for continuously combining successive scans of said analogue video signal with one of said range of sawtooth waveforms selected according to the position in said series of the scan being currently reproduced, and means for deriving an output signal representative of the screened version of said video input signal.
Claim 2
Dependent Claim
123 words
Apparatus for electronic screening of a graphic image to be reproduced by printing and wherein an analogue video signal representing the optical density variations of said graphic image is continuously produced, said apparatus comprising: means for generating a range of sawtooth waveforms, means for accepting said analogue video signal, during the generation of each dot which will form a part of the half tone image when reproduced, as a series of successive scans, means for continuously combining successive scans of said analogue video signal with one of said range of sawtooth waveforms selected according to the position in said series of the scan being currently reproduced, and means for deriving an output signal representative of the screened version of said video input signal.
Claim 3
Dependent Claim
60 words
Apparatus as claimed in claim 1, comprising a ramp generator for producing a sawtooth waveform, a timing circuit for controlling said ramp generator and means in combination with said ramp generator for producing said range of sawtooth waveforms, network means fed from the output of said ramp generator and means for feeding said analogue video signals to said network means.
Claim 4
Dependent Claim
63 words
Apparatus as claimed in claim 2, wherein said means for producing said range of sawtooth waveforms comprises at least two non-linear amplifiers fed from said ramp generator, a separate network means connected to each non-linear amplifier, a separate comparator connected to the output of each network means, and means for selectively deriving said screened video output signal from the outputs of said comparators.
Claim 5
Independent Claim
119 words
A method of electronic screening of a graphic image to be reproduced by printing and wherein an analogue video signal representing the optical density variations of said graphiC image is continuously produced, said method including the steps of: generating a range of sawtooth waveforms, accepting said analogue video signal, during the generation of each dot which will form a part of the half tone image when reproduced, as a series of successive scans, continuously combining successive scans of said analogue video signal with one of said range of sawtooth waveforms selected according to the position in said series of the scan being currently reproduced, and deriving an output signal representative of the screened version of said video input signal.
Claim 6
Independent Claim
119 words
A method of electronic screening of a graphic image to be reproduced by printing and wherein an analogue video signal representing the optical density variations of said graphiC image is continuously produced, said method including the steps of: generating a range of sawtooth waveforms, accepting said analogue video signal, during the generation of each dot which will form a part of the half tone image when reproduced, as a series of successive scans, continuously combining successive scans of said analogue video signal with one of said range of sawtooth waveforms selected according to the position in said series of the scan being currently reproduced, and deriving an output signal representative of the screened version of said video input signal.
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) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |