Plate-making method and plate-making apparatus

An on-press drawing lithographic printing method comprising:

• attaching a plate material onto a plate cylinder of a press;
• forming an image directly on the plate material by an ink jet process of ejecting an oil ink from a recording head using an electrostatic field based on signals of image data to prepare a printing plate;
• and
• performing lithographic printing using the printing plate in that state,
• wherein prevention of coagulation and/or precipitation of the oil ink particles is performed at least in a circulation of the oil ink.

A plate-making apparatus comprising:

• image-forming means forming an image directly on a plate material by an ink jet drawing device which ejects an oil ink from an ejection head using an electrostatic field based on signals of image data;
• and
• image-fixing means fixing the image formed by the image-forming means to obtain a printing plate,
• wherein at least one coagulation and/or precipitation-preventing means is provided on the flow path of the oil ink at least in a circulation of the oil ink.

An on-press drawing lithographic printing apparatus comprising:

• image-forming means forming an image directly on a plate material attached to a plate cylinder of a press based on signals of image data, the image-forming means being an ink jet drawing device comprising a recording head which ejects an oil ink using an electrostatic field;
• and
• lithographic printing means performing lithographic printing using a printing plate having thereon the image formed by the image-forming means,
• wherein at least one coagulation and/or precipitation-preventing means is provided on the flow path of the oil ink at least in a circulation of the oil ink.