Abstract: In an electrophotographic copier, adjustments are made to synchronize copy sheet gating optics start of scan, and document conveyor registration. The adjustment to the copy sheet gating is effected by making a copy with the optics assembly inactivated, determining the length of undeveloped area adjacent to the leading or trailing edge of the copy, and adjusting the start of scan as a function of the determined length. The start of scan of the optics assembly is effected by positioning a test master document with dark portions adjacent to its leading and trailing edges, making a copy of the test master document, determining the length of undeveloped area adjacent to the leading or trailing edge of the copy, and adjusting the start of scan as a function of the determined length.

Abstract: An electrophotographic copier having a toner concentration control apparatus which periodically effects a toner-patch test cycle during which the optical density of toner deposited on a photoconductor test area is measured, as by light reflectance. A time period of copier non-use, exceeding a preset time period, or a copier on/off operation, referred to as critical events, results in a transient mode of copier operation which includes reduction of photoconductor charge magnitude during the next subsequent use, independent of the extent of the prior copier use history. During such subsequent use, the toner-patch test cycle is operable to effect closed-loop control of changing the photoconductor's charge magnitude back to its nominal working value. More specifically, so long as the results of a toner-patch test cycle indicate an acceptable toner density, the photoconductor charge magnitude is maintained at a lower than working level.

Abstract: An electrophotographic copier's magnetic brush roller applies developer material to the surface of a photoconductor drum. Two parallel centerlines define the photoconductor drum surface a fixed gap distance from the magnetic brush roller's mating surface. Moving the magnetic brush roller adjusts the gap distance between the mating surfaces. Two sandwiches of conventional, standard-thickness, flexible, plastic sheets form tools; one having a total thickness slighty larger than the desired gap between the mating surfaces of the drum and roller, and the other having a thickness slightly less than the desired gap. The desired gap is set by separating the drum and roller surfaces, inserting the tool that is slightly smaller than the gap and closing the gap sufficiently so that each of the mating surfaces on the drum and roller contacts one surface of the tool.