Color printing machine

Claim 1

A color printing machine for color printing a running web of paper comprising a plurality of printing units each having a plate cylinder and an impression cylinder, and a web length adjusting means provided between each pair of the adjacent printing units for adjusting the length of the web existing between each pair of the adjacent printing units so as to be equal to the printing length multiplied by an integer, further comprising: a pair of feed rolls for feeding the web into the printing machine; a pair of pull rolls for pulling the web out of the printing machine; said plate cylinder adapted to carry a printing plate thereon and having a circumference which is greater than the length of the printing plate; said impression cylinder adapted to press the web against the printing plate mounted on said plate cylinder; a motor for driving said plate cylinders of the printing units; a reversible motor for driving said feed rolls and said pull rolls to selectively advance and back the web; a setting means for setting the circumference of said plate cylinder and the printing length and for generating a first signal proportional to the circumference of said plate cylinder and a second signal proportional to the printing length; a signal generating means for generating a third signal proportional to the number of rotations of said motor for driving said plate cylinders; a further signal generating means for generating a fourth signal proportional to the web speed; and a speed control means for receiving said first and second and third and fourth signals and for electrically controlling the speed of said reversible motor in response thereto so that the web will run at the same speed as the circumferential speed of the printing plates during the period from the start of one printing length to its end and so that the web speed integrated from the start of one printing to its end will be equal to one printing length and so that the web speed integrated from the end of one printing length to the start of the next printing length will be equal to zero, and so that the circumferential speed of the plate cylinder integrated from the start of one printing length to the start of the next printing length will be equal to the circumference of said plate cylinder.