초록 ▼

The invention provides a device for offset and similar printing from a continuous tone original to produce a halftone image on a photosensitive layer comprising means for screening the information via a first array of parallely extending lines of effective minimum optical density and a second array

The invention provides a device for offset and similar printing from a continuous tone original to produce a halftone image on a photosensitive layer comprising means for screening the information via a first array of parallely extending lines of effective minimum optical density and a second array of parallely extending lines of effective maximum optical density, the arrays being interposed to form a composite array of substantially parallel, spaced-apart, alternating lines of effective maximum and minimum optical density, the lines delimiting therebetween zones of effective graduated optical density, the gradient inside each zone progressively varying from low optical density adjacent lines of the first array to high optical density adjacent lines of the second array, the spacing of lines of the first array being between about 100 and 400 lines per inch and wherein the resulting thickness of each reproduced line on a resulting developed photosensitive layer, generated by screening the information via the array, continuously varies as a function of the density of each information point of the original.

대표청구항 ▼

A device for offset and similar printing from a continuous tone original to produce a halftone image on a photosensitive layer comprising means for screening said information via a first array of parallely extending lines of effective minimum optical density and a second array of parallely extending

A device for offset and similar printing from a continuous tone original to produce a halftone image on a photosensitive layer comprising means for screening said information via a first array of parallely extending lines of effective minimum optical density and a second array of parallely extending lines of effective maximum optical density, said arrays being interposed to form a composite array of substantially parallel, spaced-apart, alternating lines of effective maximum and minimum optical density, said lines delimiting therebetween zones of effective graduated optical density, the gradient inside each zone progressively varying from low optical density adjacent lines of said first array to high optical density adjacent lines of said second array, the spacing of lines of said first array being between 100 and 400 lines per inch and wherein the resulting thickness of each reproduced line on a resulting developed photosensitive layer, generated by screening said information via said array, continuously varies as a function of the density of each information point of the original. A method for generating a halftone image from a continuous tone original comprising outputting the information of the original onto an unexposed scanner-type film, in an electronic output simulating a screen format, the pattern of this screen being a first array of parallely extending lines of effective minimum optical density and a second array of parallely extending lines of effective maximum optical density, said arrays being interposed to form a composite array of substantially parallel, spaced-apart, alternating lines of effective maximum and minimum optical density, said lines delimiting therebetween zones of effective graduated optical density, the gradient inside each zone progressively varying from low optical density adjacent lines of said first array to high optical density adjacent lines of said second array, the spacing of lines of said first array being between about 400-600 lines per inch and developing in a lith developer containing a hydroquinone developing agent in combination with carbonate, bicarbonate and halide salt together with sodium formaldehyde sulfoxylate and formaldehyde wherein a resulting thickness of each resulting line generated on said scanner type film continuously varies as a function of each information point of the original, but does not decrease in the Dmin region beyond 5 microns width even when the generated line becomes segmented.