GB643330A - Improvements in or relating to the half-tone reproduction of documents or the like - Google Patents
Improvements in or relating to the half-tone reproduction of documents or the likeInfo
- Publication number
- GB643330A GB643330A GB13509/47A GB1350947A GB643330A GB 643330 A GB643330 A GB 643330A GB 13509/47 A GB13509/47 A GB 13509/47A GB 1350947 A GB1350947 A GB 1350947A GB 643330 A GB643330 A GB 643330A
- Authority
- GB
- United Kingdom
- Prior art keywords
- image
- photo
- shade
- mask
- slots
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/024—Details of scanning heads ; Means for illuminating the original
- H04N1/032—Details of scanning heads ; Means for illuminating the original for picture information reproduction
- H04N1/036—Details of scanning heads ; Means for illuminating the original for picture information reproduction for optical reproduction
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/40—Picture signal circuits
- H04N1/405—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
- H04N1/4055—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern
- H04N1/4056—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern the pattern varying in one dimension only, e.g. dash length, pulse width modulation [PWM]
Abstract
643,330. Copying telegraphy ; modulating tight. ETABLISSEMENTS E. BELIN. May 20, 1947, Nos. 13509 and 13510. Convention dates, May 8, 1946 and April 24, 1947. [Class 40 (iii)] In a system for reproducing a document, means are provided for converting each shade of the original into a current whose magnitude is a function of the shade and then converting this modulated current into a plurality of intermittent luminous signals which are constant in intensity but variable both in duration and spacing. In a system designed to produce half-tone plates for printing on fabrics the multi-shade original is scanned photo-electrically in a known manner and the modulated picture currents are applied to the deflecting system of a mirror oscillograph. A light source A, Fig. 4, of constant intensity is focused on to an arcuate slot F, the image of which is reflected from the oscillograph mirror M through a mask G and rotating obturating disc D on to a photo-electric cell C. The amplifier output from this cell is applied to an oscillograph which reflects light through a slotted mask on to a photo-sensitive recording surface B in known manner. The light issuing from the obturating disc may instead impinge directly on a photo-sensitive receiving surface, or the output from the photo-electric cell may control an engraving tool. The mask G has a triangular aperture H, Fig. 3, and the height at which the arcuate image S impinges on this aperture and therefore the length of image exposed is dependent on the amplitude of the picture signal, i.e. is a function of the shade being scanned. The obturating disc D comprises a number of slots J, Fig. 2, and other apertures K so arranged that the number of apertures passing the image S is proportional to the distance of the image from the centre O of the disc. Thus a black signal deflects the image S to the base of the triangular aperture H producing a wide beam which is repeated twelve times per revolution of the disc D, an almost white signal deflecting the image S to the top of the aperture H and producing a narrow beam which is repeated nineteen times. In a second embodiment the obturating disc D<SP>1</SP>, Fig. 7, comprises four rings of slots J<SP>1</SP>, comprising 14, 18, 24 and 28 slots respectively. The mask G is formed with an additional rectangular aperture I for each possible transition from one ring to the next and a second, rectangular, image S<SP>1</SP> is reflected by the mirror M on to the mask G. When the image S is moving downwards during a transition to a darker shade and begins to overlap two rings of slots J<SP>1</SP>, the auxiliary image S<SP>1</SP> begins to impinge on an auxiliary slot I to energize an auxiliary photo-electric cell and feed back a current which causes the mirror M to increase the downward movement of the main image S. This feed-back arrangement ensures a rapid transition of the image S from one ring of slots J<SP>1</SP> to the next, until with the auxiliary slot I completely illuminated a state of equilibrium is reached since any further downward movement tends to decrease the illumination of the auxiliary slot and make the images rise again. If, now a lighter tint is scanned, the images S, 8<SP>1</SP> tend to rise, the auxiliary slot I receives less illumination and the resultant feed-back current assists the rapid rise of the image S to the upper ring of slots J<SP>1</SP>. If, however a darker tint is scanned, the image S tends to move downward and this tendency is retarded by the resulting feed-back current due to the decrease in light passing through the auxiliary slot I. The only ill-effect of this retardation is to reproduce a rather lighter shade than desired until the image S<SP>1</SP> has left the auxiliary slot 1. Since, with a flat-tint original, any variations in the positioning of the main image S within the limits of a particular slot J<SP>1</SP> are due to unwanted irregularities in the tint being scanned a stepped form of triangular aperture H may be employed to reproduce such an original, Fig. 9. This irregular movement of the image S will then give rise to no change in the width of the light beam uncovered by the mask G. The recording cylinder B may be mounted on the same shaft as that carrying the original document.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR56772T | 1947-04-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB643330A true GB643330A (en) | 1950-09-20 |
Family
ID=8690925
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB13509/47A Expired GB643330A (en) | 1947-04-24 | 1947-05-20 | Improvements in or relating to the half-tone reproduction of documents or the like |
Country Status (4)
Country | Link |
---|---|
US (1) | US2524531A (en) |
CH (1) | CH262573A (en) |
FR (2) | FR928110A (en) |
GB (1) | GB643330A (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2796534A (en) * | 1951-01-23 | 1957-06-18 | Wilbespan Res Labs Inc | Photo-electric tone generator |
US2892124A (en) * | 1955-11-09 | 1959-06-23 | Rabinow Jacob | Noise discriminating, high gain automatic headlight dimmer |
US2978590A (en) * | 1956-04-20 | 1961-04-04 | Intelligent Machines Res Corp | Scanning apparatus |
US3196279A (en) * | 1962-06-12 | 1965-07-20 | Control Company Inc Comp | Photosensitive digital shaft encoder |
US3334226A (en) * | 1963-12-30 | 1967-08-01 | Exxon Production Research Co | Apparatus for simulataneously measuring fluid density and flow rate on a single photographic film |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB294508A (en) * | 1927-04-14 | 1928-07-16 | Arthur Oswald Thomas Yeo | Improvements in or relating to musical instruments |
US2063998A (en) * | 1930-12-13 | 1936-12-15 | Bell Telephone Labor Inc | Electro-optical system |
FR743655A (en) * | 1931-03-04 | 1933-04-03 | ||
US2152348A (en) * | 1936-08-07 | 1939-03-28 | William G H Finch | Telepicture recording system |
US2287033A (en) * | 1938-05-28 | 1942-06-23 | Columbia Broadcasting Syst Inc | Method and apparatus for television |
US2274841A (en) * | 1940-04-16 | 1942-03-03 | Rca Corp | Photo radio system |
US2294643A (en) * | 1940-07-05 | 1942-09-01 | Interchenical Corp | Method and apparatus for reproducing pictures |
US2357938A (en) * | 1941-11-25 | 1944-09-12 | Interchem Corp | System for controlled intermittent illumination |
US2347015A (en) * | 1942-09-17 | 1944-04-18 | Press Ass Inc | Means of compensating for drift of photoelectric devices and associated circuits |
US2432123A (en) * | 1945-04-05 | 1947-12-09 | Bell Telephone Labor Inc | Translation of visual symbols |
-
1946
- 1946-05-08 FR FR928110D patent/FR928110A/en not_active Expired
-
1947
- 1947-04-24 FR FR56772D patent/FR56772E/en not_active Expired
- 1947-05-07 US US746442A patent/US2524531A/en not_active Expired - Lifetime
- 1947-05-08 CH CH262573D patent/CH262573A/en unknown
- 1947-05-20 GB GB13509/47A patent/GB643330A/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
CH262573A (en) | 1949-07-15 |
US2524531A (en) | 1950-10-03 |
FR928110A (en) | 1947-11-19 |
FR56772E (en) | 1952-10-06 |
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