Abstract: A technique for implementing dynamic S curve stepper motor velocity profiles provides improved performance in controlling the motion of a mass. A method for controlling a moving mass comprises accelerating the moving mass according to a velocity profile, detecting that the moving mass has a specified position, and altering the velocity profile based on the detection of the moving mass having the specified position. The velocity profile is altered by reducing a maximum velocity of the moving mass, if the moving mass has the specified position before a maximum velocity of the velocity profile is achieved.

Abstract: A high voltage multiplexer, useful in power supplies for electrophotographic printers, that converts a high voltage DC input into an AC modulated DC signal that is selectively applied to one of a plurality of outputs. The selected output depends on signals applied to a set of control inputs. That multiplexer is useful in a power supply system having a high voltage DC source for producing the DC input and a clock input for setting the AC modulation frequency. That power supply is useful in an electrophotographic printer having a plurality of developers and a controller. The power supply system then selectively powers one of the developers as directed by signals from the controller.

Abstract: A document background control system having a sensor in the optical path of a reproduction machine to sense the background of a document in the copy mode during the scanning of the document to adjust the illumination of the document and also includes a control to adjust the charging potential on the photoconductor in response to document background that is non-white.