Patent ID: 8171848

Claim:
A method of manufacturing a printing plate, the method comprising the steps of: providing at least one transparent sachet having one side, which is not sealed, according to a molding specification requirement of the printing plate; pouring a liquid photopolymer into the transparent sachet to form a liquid photopolymer transparent sachet, wherein a free input quantity of the liquid photopolymer may be greater than an estimated quantity of the printing plate; providing a lower transparent clamping plate; evenly placing the liquid photopolymer transparent sachet onto the lower transparent clamping plate, wherein a negative film for plate making is to be placed below the liquid photopolymer transparent sachet such that the negative film is interposed between the liquid photopolymer transparent sachet and the lower transparent clamping plate, or the negative film for plate making is to be placed above the liquid photopolymer transparent sachet; disposing thickness gauges around the transparent sachet, wherein a thickness of each of the thickness gauges is equal to a sum of a predetermined thickness of the printing plate, a thickness of two layers of the transparent sachet and a thickness of the negative film; providing at least one thrust rod, which can roll or slide freely and has a diameter or height smaller than the thickness of the thickness gauge, to press against the liquid photopolymer transparent sachet in parallel to the side, which is not sealed, at a position distant from the side, which is not sealed, by a distance such that a stop end, which is movable relative to the liquid photopolymer contained in the liquid photopolymer transparent sachet, is formed to temporarily stop the liquid photopolymer so that the liquid photopolymer contained in the liquid photopolymer transparent sachet is higher than the thickness gauge to prevent the liquid photopolymer from flowing to the side of the liquid photopolymer transparent sachet, which is not sealed; providing an upper transparent clamping plate to press against the lower transparent clamping plate evenly and thus to flatten the liquid photopolymer transparent sachet to a thickness the same as the thickness of the thickness gauge, wherein the liquid photopolymer, which is contained in the liquid photopolymer transparent sachet and higher than the thickness gauge, can freely flow to the side, which is not sealed, during the flattening and push the thrust rod outwards until the thrust rod is stopped naturally so that the liquid photopolymer contained in the liquid photopolymer transparent sachet is formed into a uniform liquid photopolymer layer, which has a predetermined thickness and serves as a printing plate body for exposure and hardening procedures according to a size of the negative film; taking an exposed printing plate body out of the transparent sachet after the exposure and hardening procedures are finished; and performing a washing procedure to finish the printing plate.