Hydrophobically coated printhead
View Patent ↗A printhead comprising a plurality of nozzles formed on a substrate is provided. Each nozzle comprises a nozzle chamber, a nozzle opening defined in a roof of the nozzle chamber and an actuator for ejecting ink through the nozzle opening. At least part of an ink ejection face of the printhead is hydrophobic relative to the inside surfaces of each nozzle chamber. An advantage of this arrangement is that the hydrophobic ink ejection surface assists in ink ejection and minimizes cross-contamination by flooding between adjacent nozzles.
1. A printhead comprising a plurality of nozzles formed on a substrate, each nozzle comprising a nozzle chamber, a nozzle opening defined in a roof of the nozzle chamber and an actuator for ejecting ink through the nozzle opening, wherein at least part of an ink ejection face of the printhead comprises a layer of hydrophobic material, and said hydrophobic material is a silyl compound comprising a hydrophobic group.
2. The printhead of claim 1 , wherein each roof forms at least part of the ink ejection face of the printhead, each roof having a hydrophobic outside surface relative to the inside surfaces of each nozzle chamber.
3. The printhead of claim 1 , wherein each nozzle chamber comprises a roof and sidewalls walls formed from a ceramic material.
4. The printhead of claim 3 , wherein the ceramic material is selected from silicon nitride, silicon oxide or silicon oxynitride.
5. The printhead of claim 3 , wherein the roof and sidewalls are formed by a chemical vapour deposition process.
6. The printhead of claim 1 , wherein the ink ejection face is hydrophobic relative to ink supply channels in the printhead, the ink supply channels being configured to supply ink to each nozzle.
7. The printhead of claim 1 , wherein inside surfaces of each nozzle chamber lack the layer of hydrophobic material.
8. The printhead of claim 7 , wherein the hydrophobic material is covalently bonded to at least part of the ink ejection surface.
9. The printhead of claim 7 , wherein the hydrophobic material is selectivity deposited onto the ink ejection face by a process of:
(a) filling nozzle chambers on the printhead with a liquid; and
(b) depositing a hydrophobizing compound onto the ink ejection face of the printhead.
10. The printhead of claim 9 , wherein the liquid is an inkjet ink.
11. The printhead of claim 9 , wherein the step of filling the nozzle chambers is priming the printhead with ink.
12. The printhead of claim 9 , wherein the deposition of the hydrophobizing material is chemical vapour deposition.
13. The printhead of claim 9 , wherein the printhead face comprises atoms available for covalent bonding with the hydrophobizing material.
14. The printhead of claim 13 , wherein the atoms are oxygen or nitrogen atoms.
15. The printhead of claim 9 , wherein the hydrophobizing compound is non-polymerizable in the liquid.
16. The printhead of claim 15 , wherein the hydrophobizing compound is a silyl monochloride.