PRINTING SYSTEM HAVING FOUR-WAY VALVE FOR PRINTHEAD
A printing system having a media width printhead, a fluid container fluidically interconnected with the printhead via a closed fluid flow loop, a bypass fluid path bypassing the printhead on the closed loop, a gas vent on the closed loop and a four-way valve on the closed loop for selectively allowing fluid flow along the closed loop via the printhead and the bypass path and venting of gas in the closed loop via the gas vent.
1 . A printing system comprising:
a media width printhead;
a fluid container fluidically interconnected with the printhead via a closed fluid flow loop;
a bypass fluid path bypassing the printhead on said closed loop;
a gas vent on said closed loop; and
a four-way valve on said closed loop for selectively allowing fluid flow along said closed loop via the printhead and the bypass path and venting of gas in said closed loop via the gas vent.
2 . A system according to claim 1 , wherein said closed loop comprises a first path between the container and one longitudinal end of the media width of the printhead and a second path between the container and the other longitudinal end of the media width of the printhead.
3 . A system according to claim 2 , wherein the bypass path bridges across the printhead between the first and second paths.
4 . A system according to claim 2 , wherein the gas vent and the valve are located on the first path.
5 . A system according to claim 2 , wherein the gas vent comprises a filter disposed at one end of a vent line, the opposed end of the vent line joining the first path.
6 . A system according to claim 5 , wherein the filter comprises expanded polytetrafluoroethylene
7 . A system according to claim 5 , wherein said closed loop, bypass path and vent line comprise fluid hoses.