Abstract: Modulation of the edge erase lamps in a copier/duplicator/printer to record visual data in the normally unused margins of a copy/duplicate/print. Numerical information can be recorded by a controlled switching sequence of the lamps normally used for edge erasing on electrophotostatic type copiers (or duplicators or printers). Turning off an edge erase lamp causes a dark streak near the margin on the copy in line with the lamp so switched off. By selectively turning off and on combinations of a plurality of edge erase lamps, visual data such as numerals can be written in the margins while copies (or duplicates or prints) are being produced.

Abstract: Method and apparatus for improved error logging by integrating errors over a given number of operations that provides long memory and fast recovery. Errors integrated over a selected number of associated operations are compared to a criterion. An exception is logged each time the number of errors is not less than the criterion but if the number of errors is less than the criterion, the exception log is cleared.

Abstract: Copy sheets produced by varying copier machine subsystems for analyzing subsystems' performance. By varying parameters, sequencing the coronas, and inhibiting the various subsystems of a copy machine in certain orders, the resulting copy sheets can be analyzed for indications of the subsystems' efficiency. The order of operation reduces or eliminates the subsystems interacting effects so that the degradated operation of a particular subsystem can be perceived.

Abstract: A head is moved toward and rotated against an abrasive while its resistance is monitored by a four-lead bridge. Two leads from the head are connected to two slip rings, and each slip ring has two pairs of brushes, each wire from the bridge going to a different brush pair. The number of head rotations is counted and head resistance is monitored by the bridge at predetermined counts. Head movement toward the abrasive is terminated when a predetermined head resistance is detected by the bridge.