Manufacturing method for planographic printing plate for color printing
The invention provides a method for forming planographic printing plates for color printing using a plurality of hues. The method includes at least: image-forming using an amplitude modulation screen only for a planographic printing plate used for printing black color used on a first drum of a printing machine; and image-forming using a frequency modulation screen for a planographic printing plate other than the planographic printing plate used for the first drum. The amplitude modulation screen preferably has a dot line number of 300 or less. The frequency modulation screen preferably has a dot size of 30 μm or less. The planographic printing plates prepared in accordance with the method are preferably used for four-color printing of yellow, magenta, cyan and black.
1 . A method for forming planographic printing plates for color printing using a plurality of hues, comprising:
image-forming using an amplitude modulation screen only for a planographic printing plate used for printing black color used on a first drum of a printing machine; and
image-forming using a frequency modulation screen for a planographic printing plate other than the planographic printing plate used for the first drum.
2 . The method of claim 1 , wherein the amplitude modulation screen has a dot line number of 300 or less.
3 . The method of claim 1 , wherein the amplitude modulation screen has a dot line number in the range of 150 to 240.
4 . The method of claim 1 , wherein the frequency modulation screen has a dot size of 30 μm or less.
5 . The method of claim 1 , wherein the planographic printing plates are used for two-color printing.
6 . The method of claim 1 , wherein the planographic printing plates are used for four-color printing of yellow, magenta, cyan and black.