Xerox Corporation

Robert D Houston

Frank J Liptak

Improved differential optical sensors are mounted at every intersection of the deflection planes of the ink droplets issued by a multi-nozzle printhead of a pagewidth ink jet printer. These sensors are located near the printing plane and gutters of the printer. They comprise first and second input apertures, each being coupled to a light source and fixedly located to direct beams of light to a confronting associated pair of output apertures. The input and output apertures are on opposite sides of the droplet deflection plane, and the input apertures are on opposite sides of a perpendicular line extending from the midpoint between the pair of output apertures. The light beams impinge the pair of output apertures thereby creating differentially detected zero-crossing optical axes at predetermined angles with respect to the perpendicular line therefrom. The output apertures are coupled to differential circuitry via photodetectors, so that horizontal droplet position may be determined relative to droplet charge voltage and vertical droplet position may be measured in absolute value above the output apertures.

Ink droplet sensors for ink jet printers

In an ink jet printer, improved ink droplet sensing method and apparatus. The disclosed full width ink jet printer includes a number of ink jet nozzles which direct ink droplets to specific regions of a print plane. The present sensing technique insures ink drops from the multiple nozzles 'stitch' together properly across the printing plane. Multiple sensing sites (two for each nozzle) are comprised of a light input optical fiber and two output fibers coupled to circuitry to monitor light intensity at the sensing site. The sensitivity of the site is enhanced by electroformed input and output masks which reduce the effective send and receive area of the optical fibers.

Ink jet sensor method and apparatus

A continuous drop, electrostatic deflection ink jet or liquid drop printing system is disclosed. An integrated waveguide or optical fiber drop sensor array is positioned adjacent a target to be printed on the upstream side. A test gutter is positioned on the downstream side of the target. The sensor array is normally used when a target is not in position for printing to calibrate the charging voltages for a plurality of drop streams. The object is to compose a straight or print line with segments of the line being composed by each of the plurality of drop streams. The sensor array includes two optical fiber sensors for each drop stream made up of an input fiber spaced from two output fibers called A and B fibers. Groups of the A and B fibers are terminated at common photodetectors requiring the A and B fibers to cross each other's paths. This is achieved in an integrated waveguide structure by fabricating the A fibers in one plane and the B fibers in a second plane.

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Marion, NY, United States of America

Robert D Houston