Patent ID: 7213902

Claim:
A method for shutting down an ink jet printhead of a ink jet printing station, wherein the ink jet printing station comprises a drop generator with an inlet and outlet, an orifice structure, a plurality of jets, at least one filter in a fluid supply line, a fluid supply pump connected to the drop generator, a fluid line, a fluid return line with a cross flush valve, a reservoir, and a source of pressurized air and a cleaning fluid source, wherein the method comprises the steps of: a. maintaining a constant positive pressure at the drop generator to shut down the ink jet printhead, wherein the constant positive pressure ranges between 0.1 psi and 35 psi, and wherein the constant positive pressure is maintained by the steps of i. ensuring the cross flush valve closes the fluid return line connected to the outlet to create the constant positive pressure on the filter and the drop generator causing fluid to flow out of the orifice structure into the fluid line; ii. stopping the flow of fluid from the fluid supply line; b. circulating cleaning fluid from a cleaning fluid source through at least one filter, into the drop generator, out through the orifice structure, into the fluid line, and into the reservoir; and c. flowing clean pressurized air through the at least one filter, the drop generator, the orifice structure, and the fluid line to displace substantially all the cleaning fluid from the at least one filter, drop generator, and orifice structure; d. evacuating the fluid line prior to step of circulating cleaning fluid.