Multi-color offset printing method and apparatus

A multi-color offset printing method for performing multi-color printing by feeding color inks, respectively, to a plurality of corresponding plates mounted on plate cylinders, transferring the inks through blanket cylinders to printing paper in a predetermined order of colors, said method comprising:

• a first ink feeding step for feeding the color inks from ink feeders opposed to a first plate cylinder with a plate mounted peripherally thereof and defining m (m being an integer 1 or more) image areas, said color inks fed corresponding in color to said image areas, respectively;
• a second ink feeding step for feeding the color inks from ink feeders opposed to a second plate cylinder with a plate mounted peripherally thereof and defining m image areas, said color inks fed corresponding in color to said image areas, respectively;
• a first ink transferring step for transferring said color inks from said plate mounted peripherally of said first plate cylinder to a first blanket cylinder equal in diameter to said first plate cylinder and rotating in contact with said first plate cylinder;
• a second ink transferring step for transferring said color inks from said plate mounted peripherally of said second plate cylinder to a second blanket cylinder equal in diameter to said second plate cylinder and rotating in contact with said second plate cylinder;
• an ink adjusting step for rotating an impression cylinder at least 2 m times, said impression cylinder having a sheet mounted peripherally thereof and rotating in contact with said first blanket cylinder and said second blanket cylinder;
• and
• a printing step for feeding printing paper to an outer periphery of said impression cylinder rotating in contact with said first blanket cylinder and said second blanket cylinder, and discharging said printing paper from said outer periphery of said impression cylinder after rotating said impression cylinder m times.

A multi-color offset printing apparatus for performing multi-color printing by feeding color inks, respectively, to a plurality of corresponding plates mounted on a plate cylinder, transferring the color inks through a blanket cylinder to printing paper in a predetermined order of colors, said apparatus comprising:

• a plate cylinder with plates mounted peripherally thereof and defining n (n being an integer 2 or more) image areas;
• a blanket cylinder equal in diameter to said plate cylinder and rotatable in contact with said plate cylinder;
• an impression cylinder having a gripper disposed peripherally thereof for holding a forward end of printing paper, said impression cylinder being rotatable in contact with said blanket cylinder;
• and
• a controller for rotating said impression cylinder at least 2 n times, with said gripper holding a sheet.