Browse Prior Art Database

Direct Photoprinting of Negatives

IP.com Disclosure Number: IPCOM000073493D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 3 page(s) / 41K

Publishing Venue

IBM

Related People

Smith, GL: AUTHOR

Abstract

The apparatus shown is a computer controlled photoprinter. Cathode ray tube 10 repeatedly produces a single-line vertical scan on its screen. This single-line scan is focussed by lens 12 onto film 14. Segments of the scan, called scan items, are alternately black and white. By controlling the length of the scan items, the black and white portions of a character covered by a single scan can be duplicated by the cathode ray tube. The characters are formed on the film 14 by horizontally indexing lens 12 between each scan. The effect is to paint the character on film 14 in a manner similar to television images appearing on a television screen.

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Direct Photoprinting of Negatives

The apparatus shown is a computer controlled photoprinter.

Cathode ray tube 10 repeatedly produces a single-line vertical scan on its screen. This single-line scan is focussed by lens 12 onto film
14. Segments of the scan, called scan items, are alternately black and white. By controlling the length of the scan items, the black and white portions of a character covered by a single scan can be duplicated by the cathode ray tube. The characters are formed on the film 14 by horizontally indexing lens 12 between each scan. The effect is to paint the character on film 14 in a manner similar to television images appearing on a television screen.

The indexing of lens 12 is achieved by motor 16 whose movement from right to left or left to right is controlled by scan display controls 18. The blanking and unblanking of the cathode ray beam during each vertical scan is controlled by the blank/unblank display controls 20. The blank/ unblank display controls 20 and scan display controls 18 receive their commands from computer 22.

In the normal or positive mode, black characters are printed on a white background on film 14. This is accomplished by utilizing the beam of the cathode ray tube to expose the film for each portion of the character. When it is desired to produce negative prints, white characters on a black background, it is necessary to invert the blank/ unblank signal applied to the cathode ray tube and also to insure that the black background which is printed will slightly overlap between lines so that no white space is left between lines. The overlap must, however, be controlled so as to insure that the black area being printed does not obliterate part of the character of an adjacent line.

To achieve the negative printing, a negative command from the computer is converted to an enabling signal by the display controls 20 and enables AND gate
24. A second enabling signal for AND gate 24 is also received from trigger 26, whose purpose is to be described. When en...