Method and apparatus for registration control in an electrophotographic

Abstract

A method and apparatus for controlling belt movement and separated image registration in a belt oriented full color double transfer electrophotographic print engine is disclosed. The photoreceptor and transfer belts have a ratio of lengths which is nominally equal to an integer. Independent servos control rotation of the belts driving each at a constant rotational period. The rotational periods are calculated so that their ratio is precisely equal to the above referenced integer value which is the nominal ratio of the belt lengths. A plurality of separated image creation and development control signals are provided under the control of an event timing clock. The event timing clock is preset to a predetermined modulo M value, M being the units of time for the targeted rotational period of the transfer belt, each time a reference pulse is provided from a reference station associated with the transfer belt indicating that a predetermined location on the transfer belt has arrived at the reference station. This temporally synchronizes image creation with the physical rotation of the transfer belt assuring proper registration of the images. Electrostatic binding forces between the photoreceptor and transfer belts are controlled by deposition of toner on the photoreceptor belt and selectively de-energizing a transfer corona when charged, non-image carrying, areas of the photoreceptor belt are in the transfer station. Initial, and intermediate if needed, registration of seam areas on the belts is provided for embodiments using seamed belts where the seams are inappropriate area for developing or maintaining images.