Douglas C Roberts

US Patent:

44261535, Jan 17, 1984

Filed:

Sep 16, 1982

Appl. No.:

6/419104

Inventors:

Edwin L. Libby - Longmont CO
Randall A. Maddox - Lexington KY
Douglas J. Roberts - Longmont CO

Assignee:

IBM Corporation - Armonk NY

International Classification:

G03G 1500

US Classification:

355 3R

Abstract:

Image transferring apparatus for a continuously variable reduction electrostatic copier. A single fixed aperture is employed, adjacent the object plane, to: (1) reduce image intensity variations caused by non-uniform illumination across the object plane; (2) correct for lens cos. sup. 4 losses for one mode of reduction; (3) reduce image distortions due to photoconductor drum curvature, particularly at edges; and (4) reduce image illuminance variations due to changes in reduction mode throughout a continuous range of reduction modes. In accordance with preferred embodiments, the foregoing functions are achieved notwithstanding movement in image or optical center line as a function of reduction to compensate for corner referencing objects to be copied. The single fixed aperture provides for adequate reduction in intensity variations, i. e. , in an embodiment of the invention, image intensity varies plus or minus 6% from nominal levels across the image plane as reduction mode is varied throughout the range of reduction modes.