Apparatus for supporting a printing plate for exposure

Platemaking apparatus comprising:

• A. a vertically oriented imaging station including an optical imaging system having an image plane;
• B. means for supporting a roll of photosensitive printing plate material;
• C. means for feeding a length of printing plate material from said roll into said imaging station;
• and,
• D. means for supporting said length of printing plate material in the image plane of said optical imaging system for exposure thereat;
• said supporting means comprising:
• a. a cover plate assembly including a cover plate means;
• b. a backing plate assembly including a relatively rigid backing plate member and a relatively flexible backing sheet;
• c. means for producing relative motion between said cover plate assembly and said backing plate assembly to bring them into contact with one another for supporting said photosensitive sheet therebetween, said cover plate assembly including means for clamping said relatively flexible backing sheet against said relatively rigid backing plate member to define an airtight chamber between said cover plate assembly and said relatively flexible sheet with said cover plate means of said cover plate assembly being positioned in the image plane of said-optical imaging system;
• and,
• d. means for evacuating said chamber, the evacuation of said chamber causing said relatively flexible backing sheet to be moved towards said cover plate means for pushing said photosensitive sheet firmly against said cover plate means to be held flatly thereagainst and in said image plane of said optical imaging system for exposure.