Filtered air supply for nozzle guard
View Patent ↗A printhead for an inkjet printer, with an array of nozzles for selectively ejecting drops of ink towards a print medium, and a protective structure between said nozzles and said print medium. The structure is configured so as not to obstruct ink drops ejected from the nozzles. The printhead also has an air supply for supplying positive air pressure to the protective structure, the air supply having an air intake with a filter and shut off valve for stopping air supply to the structure when the printer is in a non-printing operational mode; and, an air distribution ducting having one or more air passages in communication with the protective structure. The shut off valve has an apertured member with a plurality of apertures corresponding to each of the air passages. The apertured member is movable between a valve open position in which the air apertures are in communication with the air passages and a valve closed position in which the air apertures are not in communication with said air passages.
1. A printhead for an inkjet printer, the printhead comprising:
an array of nozzles for selectively ejecting drops of ink towards a print medium;
a protective structure situated between said nozzles and said print medium, the structure configured so as not to obstruct ink drops ejected from the nozzles;
an air supply for supplying positive air pressure to the protective structure, the air supply having an air intake with a filter and shut off valve for stopping air supply to the structure when the printer is in a non-printing operational mode; and,
an air distribution ducting having one or more air passages in communication with the protective structure, the shut off valve having an apertured member with a plurality of apertures corresponding to each of the air passages; wherein,
the apertured member is movable between a valve open position in which the air apertures are in communication with the air passages and a valve closed position in which the air apertures are not in communication with said air passages.
2. A printhead for an inkjet printer according to claim 1 wherein the protective structure is a nozzle guard defining a substantially enclosed space adjacent the array of nozzles such that the air supply means supplies positive air pressure to the substantially enclosed space.
3. A printhead for an inkjet printer according to claim 2 wherein said nozzle guard has a plurality of apertures aligned with said nozzles so that ink drops ejected from said nozzles pass through said apertures.
4. A printhead for an inkjet printer according to claim 2 wherein said nozzles are arranged in a plurality of print modules.
5. A printhead for an inkjet printer according to claim 4 wherein each print module is associated with a respective nozzle guard to define a respective space.
6. A printhead for an inkjet printer according to claim 5 wherein said air supply supplies positive air pressure to each said space.
7. A printhead for an inkjet printer according to claim 2 comprising a plurality of the substantially enclosed spaces corresponding to respective portions of the nozzle array, wherein the air supply includes means for distributing pressurized air to each said space.
8. A printhead for an inkjet printer according to claim 7 wherein said filter is provided in a replaceable ink cassette of the printer.
9. A printhead for an inkjet printer according to claim 1 wherein said air supply is discontinued when said printer is in a non-printing operational mode.
10. A printhead for an inkjet printer according to claim 1 wherein said nozzles comprise micro-electromechanical devices.
11. A printhead for an inkjet printer according to claim 1 wherein the air distribution ducting is a multi-layer laminated distribution structure.
12. A printhead for an inkjet printer according to claim 11 wherein said laminated distribution structure includes a plurality of air holes extending through at least some of said layers and transverse air passages formed between two adjacent ones of said layers, said transverse air passages leading to said spaces.