| 摘要 |
<p>The dot printer, which is of small dimensions, is used with desk top computers or as a peripheral unit with small processors. The printer writes in the serial-parallel mode by means of a thermal head (26) on a paper tape (16) wound on a writing platen (10) which advances intermittently to effect line spacing. This advancing is effected by means of a pawl (56) on a beam (50) controlled by a face cam (46) and a radial cam (48) on a cam cylinder (44) driven by a motor (45). A third cam (42) reciprocates the head (26) and, at the reversals of the head, the face cam (46) allows a spring (45) to engage the pawl (56) with a toothed wheel (62) on the platen (10) and the radial cam (48) then moves the pawl to advance the platen. The head comprises a small plate (29) of insulating material with twenty point-like resistive writing elements, and is fixed to a support (24) which is moved parallel to the cylinder by means of the third (42). A printed circuit card (71) fixed to the structure of the printer carries concentric tracks which are traversed by a sliding contact mounted on the cam cylinder (44) to produce synchronising signals for the printing pulses.</p> |
