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Computer Control Of Half Tone Printing

IP.com Disclosure Number: IPCOM000077798D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Herd, HH: AUTHOR

Abstract

This description relates to a means to print square half-tone dots with fixed exposure time and fixed source intensity. Fig. 1 represents a photographic plate with a predetermined arbitrary two-dimensional transmission function. T(x), the transmission function of x can be shaped to the purpose described below. T(x), shown in only one quadrant in Fig. 1, is repeated in the other three quadrants. It is constant along any ordinate in a quadrant triangle, but varies as the required function of the distance from apex to base. The plate can be made in a wide variety of sizes and configurations of the function. Although the square embodiment is preferred, it could be a simple circular radial distribution.

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Computer Control Of Half Tone Printing

This description relates to a means to print square half-tone dots with fixed exposure time and fixed source intensity. Fig. 1 represents a photographic plate with a predetermined arbitrary two-dimensional transmission function. T(x), the transmission function of x can be shaped to the purpose described below. T(x), shown in only one quadrant in Fig. 1, is repeated in the other three quadrants. It is constant along any ordinate in a quadrant triangle, but varies as the required function of the distance from apex to base. The plate can be made in a wide variety of sizes and configurations of the function. Although the square embodiment is preferred, it could be a simple circular radial distribution.

In Fig. 2, the plate is arranged in proximity to an electro-optic shutter with a polarizer and analyzer, and all these are set in line with a condenser source. An image of the T(x) plate is formed on the photolithographic material. The solution of the electro-optic shutter is controlled by the signal from the computer, and hence the exposure as a function of (x) is controlled on the photoplate. The overall density exposure curve at the photolithographic plate will depend on the retardation functions of the shutter, the density/exposure curve of the photolithographic plate, and the area reflection density of the printing process and ink. By either measuring these independently and combining them or merely by arbitrary cut and try,...