Patent ID: 8041240
Filing Date: 2011-10-18
Classification: G03G

Abstract:
1. A method for controlling the charge uniformity of a photoreceptor (PR) in an electrostatic marking system which comprises: running a plurality of unimaged drum or belt rotations or revolutions (run(s)) keeping the charge voltage output constant during electrostatic marking system cycle up and measuring the unimaged voltage via an electrostatic voltage meter (ESV) on said photoreceptor at a given point before a latent image is formed on said photoreceptor; recording said unimaged voltage for each unimaged run and averaging said unimaged voltages to obtain thereby an unimaged voltage signature as a function of the given point; storing said unimaged voltage signature as a function of the given point in a controller; storing said unimaged voltage signature as a function of the given point in a controller, said controller configured to calculate a difference between a desired unimaged voltage and the voltage of the photoreceptor latent imaged voltage signature and store and correct for the said unimaged voltage signature based on the difference between a desired unimaged voltage and the voltage of the photoreceptor unimaged voltage signature for subsequent imaging runs to thereby ensure a consistent unimaged voltage on the photoreceptor; said controller enabled to apply the required corrections for the said unimaged voltage signature to a charging unit and compensate for any charge voltage deviation and run-uniformity from the desired photoreceptor unimaged voltage; running a plurality of latent imaged drum or belt rotations or revolutions (run(s)) keeping the charge voltage output constant and measuring the latent imaged voltage via the ESV on said photoreceptor at the given point after a latent image is formed on said photoreceptor and including exposed areas of the photoreceptor; recording said latent imaged voltage for each latent imaged run and averaging said latent imaged voltages to obtain thereby a latent imaged voltage signature as a function of the given point; and storing said latent imaged voltage signature as a function of the given point in the controller, said controller configured to calculate a difference between a desired latent imaged voltage and the voltage of the photoreceptor latent imaged voltage signature and store and correct for the said latent imaged voltage signature based on the difference between a desired latent imaged voltage and the voltage of the photoreceptor latent imaged voltage signature for subsequent imaging runs to thereby ensure a consistent latent imaged voltage on the photoreceptor, wherein said controller is enabled to apply the required corrections for the said latent imaged voltage signature to a charging unit and compensate for any charge voltage deviation and run-uniformity from the desired photoreceptor latent imaged voltage and to supply a development station with a precise and uniform photoreceptor voltage which in turn applies a uniform amount of toner to the latent image, wherein said ESV is positioned in said electrostatic marking system between an exposure station and a development station, and wherein the voltages are averaged over at least 5 drum or belt revolutions to calculate the signatures.