| 摘要 |
Two platens having glass plates are pivotally interconnected by means of hinges and U-shaped brackets. Spring loaded fasteners hold the platens closed but the fasteners may be opened to permit the platens to pivot open. The two platens are seated one on top of the other upon a housing within which are mounted lamps which produce ultra-violet rays. The position of the platens can be reversed so that the lower platen is on top of the upper platen. There is a cavity between the closed platens for accommodation of a negative, a layer of photo-sensitive composition and bearer strips. The photo-sensitive composition is exposed to the ultra-violet rays first on one side then on the other by reversal of the positions of the platens so that both a base on one side and a raised image on the other side are formed. The thickness of the bearer strips governs the thickness of the finished printing plate. The brackets and fasteners bias the platens together with resulting pressure upon the photo-sensitive composition within the cavity during the time that the photo-sensitive composition is exposed to the ultra-violet rays.
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