Method for calibrating an electrophotographic proofing system

Abstract

A calibration procedure for an electrophotographic proofing system of the type for generating color proofs during multiple image cycle proofing runs from imaging information representative of half-tone color patterns for each of a set of colors by sequentially, during the imaging cycle for each color of the set, charging a photoconductor as a function of a charge model representative of photoconductor contrast voltages as a function of a charging grid voltage, modulating a laser as a function of the color pattern information to expose the photoconductor, and toning the exposed photoconductor as a function of a development model representative of measured developed toner color densities as a function of development voltage. The calibration procedure generates charge and development models for each color of the set during one proofing run, and includes: i) charging a plurality of first color test patches on the photoconductor, each with a different known grid voltage from a range of grid voltages; ii) exposing the first color test patches on the photoconductor; iii) measuring the contrast voltages of the photoconductor at the first color test patches; iv) toning the first color test patches as a function of known development voltages; v) measuring the of the toner at the first color test patches; vi) repeating steps i-v for each remaining color of the set during one proofing run; vii) generating a charge model, for each color of the set, representative of the measured contrast voltages as a function of the associated grid voltages; and viii) generating a development model, for each color of set, representative of the measured toner densities as a function of the associated development voltages.