Patent ID: 7800638

Claim:
A platemaking apparatus for making a printing plate, comprising: a rotatable recording drum for mounting a recording material peripherally thereof; a first emitting device for emitting a first laser beam to irradiate the recording material at a first pixel pitch, said first beam having a first beam diameter on the recording material; a second emitting device for emitting a second laser beam to irradiate the recording material at a second pixel pitch larger than said first pixel pitch, said second beam having a second beam diameter larger than said first beam diameter on the recording material; a first scanning device for causing said first laser beam emitted from said first emitting device and said second laser beam emitted from said second emitting device to scan synchronously and axially of said recording drum; a second scanning device for causing said first laser beam emitted from said first emitting device to scan the recording material at said second pixel pitch axially of said recording drum; and a controller configured to: cause the first emitting device to engrave the recording material to a first depth, cause the second emitting device to engrave the recording material to a second depth larger than said first depth, control the platemaking apparatus so as to satisfy the equation F 1= F 2·( pc/pp ), where F 1 is a scanning frequency of the said first laser beam axially of said recording drum, F 2 is a modulation frequency of said second modulating device, pp is said first pixel pitch, and pc is said second pixel pitch.