Abstract: In a typewriter environment, a carrier mounted sensor for calculating the width of a sheet of paper on the platen and for thereafter setting-up margins for that sheet of paper. In addition to supporting the sensor, the carrier supports the printhead and associated apparatus for detecting the position of the carrier relative to the platen at each escapement position of the carrier. The sensor starts its scan at the extreme left position of the carrier and senses the left edge of the paper at a transition from dark-(the platen surface) to-light (the sheet of paper). This transition point is detected and stored. The carrier continues its rightward scan and the right edge of the sheet of paper signals a transition from light-to-dark. This position is detected and stored. The carrier and sensor continue scanning to the right for a specific distance to eliminate errors that are caused by dark areas on the paper that prematurely trigger light-to-dark transitions.

Abstract: Disclosed is an ink jet printer having the capability of printing both vertically and horizontally. This is accomplished by mechanical orientation of the electric field associated with the deflection plates. In a first embodiment, the plates are mounted in such a manner as to permit rotation manually, for example, by a handle which interconnects the two plates and permit rotation thereof about the axis of the ink drop stream. In an alternate embodiment, the deflection plates are comprised of two pairs, a horizontal pair and a vertical pair which are shiftable into and out of operating position to effect the desired ink drop deflection.