| 摘要 |
PURPOSE:To provide a laser plate-making system capable of a stable focusing control of a laser beam to be irradiated. CONSTITUTION:A laser plate-making system consisting of a rotary plate cylinder 12, a laser beam source 31 to irradiate a laser beam to a plate sheet 13 which is wrap-mounted to this plate cylinder, and a focusing control mean 33 to adjust a focusing of a laser beam from this laser beam source 31. Usually an optical servo to irradiate a laser beam is controlled. depending on a detected focusing of a laser beam. When this optical servo control cannot be made, a control position of the focusing control means 33 is controlled by a capacitance servo to irradiate a laser beam, depending on a detected capacitance occurring between the two electrode plates fitted near this control means. |
