| 摘要 |
<p>A vacuum contact system has a vacuum contact frame including a bi-layer blanket (1) having top and bottom layers (12, 13) spaced apart by a number of parallel strip members (20) to define a first space (19). A bead (14) is positioned around the outer edges of the top layer (12) to support a glass plate (15) so that a second space (17) is formed. Vacuum connectors (16) communicate with the second space and a further vacuum connector (18) communicates with the first space, all the connectors being connected to a vacuum pump (38). The first and second spaces have the atmosphere therein controlled by electromagnetic valves (39, 40) located in a vacuum circuit with the pump (38).</p><p>In operation a film master (28) and a presensitised material (27) are located in the second space (17) and the vacuum circuit is arranged to remove air from both the first and second spaces (17, 19) so that the two layers of blanket are drawn together. Ridges (30) formed by the strip members (20) are thus formed in the top layer outer surface (12) and these ridges press the film master and presensitised material against the glass plate. The vacuum circuit is then arranged to vent the space between the two blanket layers to atmosphere so that overall contact of the blanket layer (12) is made against the film master (28) and presensitised material (27) which are thus sandwiched between the blanket layer (1) and the glass plate (15) substantially over the whole area of the film master (28). </p> |
