| 摘要 |
<p>A transparent support member of an electrostatic copier has a support surface and an opposite surface. Light sources direct light against the opposite surface and first pattern sheets are held on the support surface and define between themselves an elongated gap. A second pattern sheet overlies the first pattern sheets and is provided with lines of indicia extending parallel to the gap. A transporting arrangement transports the second pattern sheet stepwise relative to the first pattern sheets in a direction normal to the gap so as to expose succeeding ones of the lines in the gap. A transparent web provided with masking portions is located between the light sources and the opposite surface, or between the opposite surface and the first pattern sheets, and can be moved relative to the gap so that different ones of the masking portions can be placed into predetermined positions relative to the pattern sheets.</p> |
