Duplex printer including print unit shifting and web shifting mechanisms
View Patent ↗After the front surface of a web is printed by a first-side printing unit, the web is shifted in the direction of its width by a direction-changing unit, flipped over by rollers, and transported to a second-side printing unit, where the back surface of the web is printed. A sensor detects a displacement between the second-side printing unit and the web or marks printed on the web. According to the amount and direction of displacement detected by the sensor, a printing unit body is shifted in the direction of the web width, and the web traveling as opposed to the first-side printing unit is shifted in the direction of its width by an edge guide.
1. A duplex printer comprising:
a first-side printing unit for printing on one side of a traveling web;
a second-side printing unit for printing on the other side of said web;
a displacement sensor for detecting the amount of displacement between said second-side printing unit and a web which faces said second-side printing unit;
a printing-unit shift mechanism for shifting said first-side printing unit and said second-side printing unit integrally in a direction orthogonal to a direction of travel of said web according to the amount of displacement detected by said displacement sensor; and
a web control mechanism for shifting a web which faces said first-side printing unit in the direction orthogonal to the direction of travel of said web by an amount corresponding to the amount of shift caused by said printing-unit shift mechanism.
2. The duplex printer according to claim 1 , wherein
at least either one of said first-side printing unit and said second-side printing unit is an ink jet head.
3. The duplex printer according to claim 1 , wherein
said web control mechanism includes an edge guide.
4. The duplex printer according to claim 1 , wherein
said second-side printing unit is located downstream of said first-side printing unit with respect to the direction of travel of said web, and
an edge guide for correcting shifting of a web caused by said web control mechanism is provided between said first-side printing unit and said second-side printing unit.
5. A duplex printer comprising:
a first-side printing unit for printing on one side of a traveling web;
a second-side printing unit for printing on the other side of said web;
a displacement sensor for detecting the amount of displacement between a mark printed on said web by said first-side printing unit and said second-side printing unit;
a printing-unit shift mechanism for shifting said first-side printing unit and said second-side printing unit integrally in a direction orthogonal to a direction of travel of said web according to the amount of displacement detected by said displacement sensor; and
a web control mechanism for shifting a web which faces said first-side printing unit in the direction orthogonal to the direction of travel of said web by an amount corresponding to the amount of shift caused by said printing-unit shift mechanism.
6. The duplex printer according to claim 5 , wherein
at least either one of said first-side printing unit and said second-side printing unit is an ink jet head.
7. The duplex printer according to claim 5 , wherein
said web control mechanism includes an edge guide.
8. The duplex printer according to claim 5 , wherein
said second-side printing unit is located downstream of said first-side printing unit with respect to the direction of travel of said web, and
an edge guide for correcting shifting of a web caused by said web control mechanism is provided between said first-side printing unit and said second-side printing unit.