Differential fiber optic sensing method and apparatus for ink jet recorders

摘要

Optical fibers are used to sense fluid ink drops along the x, y and z axis of an orthogonal coordinate system. A drop sensing zone is defined in the narrow space between the faces of a single input fiber and two output fibers. An LED infrared light source is coupled to a remote end of the input fiber. Infrared sensitive photodiodes are coupled to the remote ends of each output fiber. The photodiodes are in turn coupled to a differential amplifier whose output represents a displacement error for the x and y axis and represents a time reference for the z axis for the case where the drop flight path is along the z axis. A plurality of sensors are disclosed in an ink recording system having a plurality of nozzles and in an ink recording system having an ink generator traversing the length of a high speed rotating drum.