DEVICE FOR AUTOMATIC MARGIN SETTING IN A TYPEWRITER IN DEPENDENCE UPON THE WIDTH, OF THE PAPER

摘要

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 proportional 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. At the end of the scan, the recorded distances yield the width of the sheet of paper and from this recorded width margins equal to a certain proportion of the total recorded width of the sheet of paper are set.