Browse Prior Art Database

CONTRAST AND BRIGHTNESS CONTROLS FOR ELECTROPHOTO-GRAPHIC DEVICES

IP.com Disclosure Number: IPCOM000025789D
Original Publication Date: 1988-Feb-29
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 96K

Publishing Venue

Xerox Disclosure Journal

Abstract

Control of the response characteristics of electrophotographic devices is desirable to allow the user to tailor operation of the device for optimization of operation for his copying or printing needs. It also allows the machine to be operated with aging materials and components and in environmental extremes that would otherwise result in copy quality failures.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

Page 1 of 2

XEROX DISCLOSURE JOURNAL

CONTRAST AND BRIGHTNESS Proposed Classification CONTROLS FOR ELECTROPHOTO- U.S. C1.355/14C GRAPHIC DEVICES
Douglas G. Boike
Cyril G. Edmunds
Kent A. Randall

Int. C1. G03g 15/00

Control of the response characteristics of electrophotographic devices is desirable to allow the user to tailor operation of the device for optimization of operation for his copying or printing needs. It also allows the machine to be operated with aging materials and components and in environmental extremes that would otherwise result in copy quality failures.

In accordance with the proposal, a device might be provided with two controls referred to as Contrast and Brightness. The Contrast control controls the slope of the solid area tone reproduction curve (TRC), while the Brightness control varies the intercept. Various combinations of Contrast and Brightness correspond to conventional electrophotographic modes. Low Contrast and Brightness would, for instance, yield a TRC similar to a conventional pictorial mode. Unlike fixed mode operation, however, the ContrasffBrightness control scheme allows for continuous variation of the control ranges. Accordingly. failures caused by material aging, environmental extremes and batch to batch materials differences may be corrected by operator intervention.

The ContrasffBrightness controls are operable by varying the electrostatic set points in the device. Developer bias, corotron charging level, and image exposure can each be controllably varied b a common ContrastiBrightness controller...