System and method for preserving inkjet operational status during long periods of printer inactivity
An inkjet printer includes a printhead maintenance station that injects a high pH fluid into the inkjet stacks of the printheads in the printer to prevent ink contamination during long periods of printer inactivity. The printhead maintenance station includes a printhead cap having an opening, a printhead vent blocking member configured to block manifold vents in the printhead when the printhead engages the printhead vent blocking member, and a valve. The valve is positioned within the printhead cap to enable the printhead cap to hold a volume of high pH fluid entering the printhead cap through the opening in the printhead cap when the valve is closed and to enable egress of the high pH fluid when the valve is opened. A printhead is lowered onto the printhead cap and a vacuum applied to an ink supply line to the printhead to inject the high pH liquid into the printhead.
1 . A printhead maintenance station comprising:
a printhead cap configured to cover a face of a printhead;
a volume of high pH fluid retained in the printhead cap, wherein the high pH fluid has a pH level of at least 8 and no more than 12;
an opening in the printhead cap, the opening configured to allow the volume of high pH fluid to enter the printhead cap;
a printhead vent blocking member configured to block manifold vents in the printhead when the printhead is moved to engage the printhead vent blocking member; and
a valve configured to open and close, the valve being positioned within the printhead cap to enable the printhead cap to hold the volume of high pH fluid in the printhead cap when the valve is closed and to enable egress of the high pH fluid from the printhead cap when the valve is opened.
2 . The printhead maintenance station of claim 1 wherein the printhead vent blocking member is made of a pliable material.
3 . The printhead maintenance station of claim 2 wherein the pliable material is either polyurethane or rubber.
4 . The printhead maintenance station of claim 1 , the opening in the printhead cap being configured to open to enable the high pH fluid to enter the printhead cap and to close to prevent a flow of the high pH fluid into the printhead cap.
5 . An inkjet printer comprising:
at least one printhead module configured with at least one printhead;
a printhead maintenance module including a volume of high pH fluid retained in a printhead cap,
the high pH fluid comprising a liquid and a base added to the liquid that raises the pH level of the liquid to at least 8 and no more than 12, and
the printhead cap having a manifold vent blocking member, an opening in the printhead cap, a printhead vent blocking member configured to block manifold vents in the printhead when the at least one printhead is moved to engage the printhead vent blocking member, and a valve configured to open and close, the valve being positioned within the printhead cap to enable the printhead cap to hold the high pH fluid entering the printhead cap through the opening in the printhead cap when the valve is closed and to enable egress of the high pH fluid from the printhead cap when the valve is opened; and
a controller operatively connected to the at least one printhead module and the printhead maintenance station, the controller being configured, during periods of inactivity of the printhead module of at least two hours, to:
fill the printhead cap with the high pH fluid;
lower the at least one printhead onto the printhead cap to block manifold vents in the printhead and contact the nozzle plate of the printhead with the high pH fluid; and
apply a vacuum to an ink supply line of the printhead to pull the high pH fluid into the printhead.
6 . The inkjet printer of claim 5 , wherein the pH level of the liquid and base is no more than 12, the controller being further configured to:
direct the high pH fluid through the opening in the printhead cap to fill the printhead cap with the high pH fluid.
7 . The inkjet printer of claim 6 , wherein the fluid is selected from the group of consisting of water, propylene glycol, hexanediol, butane diol, glycol ethers, glycerol, and surfactants, wherein the base is selected from the group consisting of triethylamine, hydrazine, dimethylethanolamine, KOH, and NaOH, and wherein the controller is further configured to:
lower the at least one printhead until the manifold vents in the at least one printhead contact the manifold vent blocking member in the printhead cap.
8 . The inkjet printer of claim 7 , the controller being further configured to:
continue to apply the vacuum to the ink supply line until the high pH fluid passes through a screen within the printhead.
9 . The inkjet printer of claim 8 , the controller being further configured to:
move the printhead away from the printhead cap to open the manifold vents in the printhead; and
continue to apply the vacuum to the ink supply line to pull the high pH fluid into the manifolds within the printhead that are fluidly connected to the manifold vents.
10 . The inkjet printer of claim 9 , the controller being further configured to:
terminate application of the vacuum to the ink supply line to enable a meniscus of the high pH fluid to be present at nozzle openings in the at least one printhead.
11 . The inkjet printer of claim 10 , the controller being further configured to:
open a printhead cap drain valve to enable the high pH fluid to egress from the printhead cap.
12 . The inkjet printer of claim 11 , the controller being further configured to:
perform a purge cycle on the printhead to flush the high pH fluid from the printhead.