| 摘要 |
<p>A continuously emitted convergent laser beam is deflected by means of a rotating polygon mirror (5), to be directed to a reflector mirror (7) having a pair of reflective surfaces, which adjoin each other at the vertex portion thereof. As the reflective surfaces of the reflector mirror (7) are scanned with the laser beam, the beam is split and alternately directed to one mirror pair (8, 9) and the other mirror pair (10, 11). The laser beam directed to each mirror pair is further divided into segment beams, which are reflected in opposite directions and condensed on a tipping paper sheet (18) by means of condensing lenses (12, 13, 14, 15). Thus, two alternate pairs of rows of perforations, four rows in total, are bored through the sheet (18). <IMAGE></p> |
