Combined central and lateral hold-down plates, and end-of-page

Abstract

Two printing-medium guide systems restrain the medium. One is in an area upstream (along the direction of medium advance) from the pen, and extending laterally across the width of the medium except in one or more regions laterally near the engagement of a print-medium advancing device. The other guide system is disposed laterally from the pen, and extends laterally across the medium only in one or more regions laterally near the engagement of the advancing device. Preferably these 'one or more regions' are only near the lateral edges of the medium--so that (1) the first guide system restrains the medium over an area that stops short (ideally about 11/2 centimeter short) of the lateral edges; and (2) the second guide system is bifurcated, disposed laterally in two directions from the pen, and restrains the medium across only the lateral edges of the medium (most preferably in a strip whose width is a few millimeters, ideally 3 mm). Preferably a human-actuable control selects a print-medium width, and shifts at least one bifurcation of the second guide system. A tensioning system, longitudinally beyond the marking head from the medium advancing device, and generally aligned laterally with that device, tensions the medium away from the advancing device to hold the medium taut at the pen. Preferably the advancing and tensioning devices are very closely spaced upstream and downstream, respectively, from the pen zone. When tensioned, the medium moves a normal distance through the apparatus at each operation of the advancing device; but after a trailing edge of the medium passes the advancing device (so that the medium is advanced only by the tensioner and no longer tensioned), the advance distance is decreased (preferably by about half).