Coulter Systems Corporation

John F Keane

John C Butler

Ronald J Duke

Lysle D Cahill

John A Lawson

Kenneth D Fraser

John L Tibbits

E Raymond Thomas

Stanley C Harting

George H Kramer

Theodore A Kessis

Gary L Frank

Timothy H Archer

Sequential scanned scaled density data representing a varying tone image is electronically screened to form binary element data that when imaged to form an array of orthogonally arranged binary elements on a member produces screened color separation plates of that original image suitable for use as the printing plates in a lithographic printing press. Screening occurs by comparing sequential density data with selected screen matrix data contained in a memory. The matrix data is ordered with density values increasing outwardly from the matrix center to the corners and edges. The matrix data is selected from matrix locations related to the desired screen frequency and angle with the selected matrix locations being determined by the application of fundamental right triangle trigonometric relationships to the matrix. Screening and imaging occurs sequentially with two density data being compared to matrix data simultaneously. The binary elements of the several plates are produced in one pass across the surface of the member.

Method and apparatus for half-tone reproduction of a varying tone

Graphics and text data are combined selectively to discharge incremental areas of a charged electrophotographic member to form thereon a latent text and/or graphics image represented by the graphics and text data, the imaged member thereafter being toned and output from the system so that the toned image may be fused on the member and the member may be used as a printing plate in an offset lithographic printing press. The apparatus includes an optical system that may form a maximum of 22 individual rays which are deflected twice through a field flattening lens and then onto the charged member. The optical system further includes an optical scale or grating which provides electrical signals indicating the precise location of the individual rays along scan lines on the member. The apparatus further includes an electronic system which generates electrical signals from the graphics and text data to form the 22 individual rays. The text data is used to modulate signals produced by the graphics data, the result of the modulation being beam control signals used to form the 22 individual rays. The apparatus further includes a toning system that provides a vertical meniscus of toning fluid, the meniscus being essentially stationary with the electrophotographic member as the electrophotographic member is rotated past the toning station.

Digital plate maker system and method

A digital plate maker system to receive graphics and text data and selectively discharge incremental areas of a charged electrophotographic member to form thereon the latent images represented by the graphics and text data, the imaged member thereafter being toned and output from the system. Thereafter, the toned image may be fused on the member and the member being used in an offset lithographic printing press. The digital platemaker system includes an optical system which may form a maximum of 22 individual rays which are direct deflected twice through a field flattening lens and then onto the charged member. The optical system further includes an optical scale or grating which provides electrical signals indicating the precise location of the individual rays along scan lines on the member. The digital plate maker system further includes an electronic system which generates electrical signals to form the 22 individual rays. The text data is used to modulate signals produced by the graphics data, the result of the modulation being the beam control signals used to form the 22 individual rays. The digital plate maker system further includes a toning system which provides a vertical meniscus which is essentially stationary with the electrophotographic member as the electrophotographic member is rotated past the toning station.

Optical system for imaging an electrophotographic member

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Bellbrook, OH, United States of America

John F Keane