Patent ID: 7611824

Claim:
A method for producing a planographic printing plate and a dummy plate for planographic printing in a CTP plate-making system, the method comprising: taking one product out of a pile of multiple planographic printing plate precursors piled up on a base substrate and a pile of multiple dummy plate precursors for planographic printing piled up on another base substrate, distinguishing the kind of the one product with a color sensor, when the one product is a planographic printing plate precursor, exposing the one product to an infrared ray, and subsequently developing the exposed one product, and when the one product is a dummy plate precursor, developing the one product, wherein a colored surface of the base substrate on which the pile of multiple planographic printing plate precursors is piled up, a colored surface of the base substrate on which the pile of multiple dummy plate precursors for planographic printing is piled up, the planographic printing plate precursor, and the dummy plate precursor for planographic printing each have a different absorption maximum in a range of 350 to 700 nm and an absorbance at the absorption maximum of 0.2 or more so that the presence or absence of the photographic printing plate precursor or the dummy plate precursor can be recognized, and wherein an interleaving paper that is different from the base substrate is placed between plates of the pile(s) of the planographic printing plate precursors and/or the dummy plate precursors.