Composite offset printing plate

Claim 1

A composite commercial printing plate for attachment to the plate cylinder of an offset printing press for applying a page of printed matter to one side of a paper passing through the press comprising, a. a thin base plate of rigid curvable material having upper and lower surfaces, and an area of a size greater than two of the pages; b. frame means including attachment means whereby said frame means is fixed to said upper surface, said frame defining at least two equally sized and shaped page size frame openings in side-by-side relation; c. an individual page size printing plate for each of said openings, each plate being sized and shaped for reception within the confines of one of said framed openings; d. attachment means whereby said individual printing plates for a page are removably attached to said upper surface within said confines and are adapted to be replaced by another page sized printing plate; e. each of said individual printing plates comprising a lithograph printing plate containing water receptive nonprinting areas and ink receptive printing areas and said composite printing plate is adapted to be fixed about the cylindrical face of the plate cylinder with saiD lower surface lying thereagainst and all of said individual printing plates being exposed for dampening and inking, and transfer of the ink from the printing areas to the paper in accordance with the lithographic offset printing process; and f. the printing plates having an outer peripheral edge and each of said frame openings having an inner peripheral edge in substantial abutment with said outer peripheral edge of said individual printing plates fixed therein which edges are rounded to merge and blend with the exposed surface defining a channel between the printing plates and the frame for accumulating moisture and fountain fluid to repel ink from accumulating therealong and avoid printing of a borderline about reproductions from the replaceable page plates.