Inkjet printer with float valve regulation of hydrostatic ink pressure
View Patent ↗An inkjet printer includes: an inkjet printhead; an ink reservoir containing a supply of ink; and a pressure-regulating chamber for maintaining ink contained therein at a predetermined first level. The chamber includes: an inlet port connected to the ink reservoir via an ink supply line; an outlet port connected to an ink inlet of the printhead via an upstream ink line; an air vent open to atmosphere; and a float valve for maintaining the predetermined first level of ink. The float valve includes: an arm pivotally mounted about a pivot; a float mounted at one end of the arm; and a valve stem attached to the arm, said valve stem having a valve head for closure of a valve seat, the valve seat being positioned at the inlet port of the pressure-regulating chamber.
1. An inkjet printer comprising:
an inkjet printhead;
an ink reservoir containing a supply of ink; and
a pressure-regulating chamber for maintaining ink contained therein at predetermined first level, said chamber comprising:
an inlet port connected to the ink reservoir via an ink supply line;
an outlet port connected to an ink inlet of the printhead via an upstream ink line;
an air vent open to atmosphere, said air vent communicating with a headspace above said ink; and
a float valve for maintaining said predetermined first level of ink by controlling a flow of ink into said inlet port, said float valve comprising:
an arm pivotally mounted about a pivot;
a float mounted at one end of said arm; and
a valve stem attached to said arm, said valve stem having a valve head for closure of a valve seat, said valve seat being positioned at the inlet port of said pressure-regulating chamber.
2. The printer of claim 1 , wherein said ink reservoir is positioned above said first level.
3. The printer of claim 1 , wherein said valve head comprises an umbrella sealing cap for closure of the valve seat.
4. The printer of claim 1 , wherein an outer surface of a base of said chamber comprises said valve seat.
5. The printer of claim 4 , wherein said float valve is configured such that downward movement of said valve stem towards said base unseats said umbrella cap from said valve seat.
6. The printer of claim 5 , wherein a positive ink pressure at said inlet port urges said umbrella sealing cap against said valve seat.
7. The printer of claim 6 , wherein the positive ink pressure is provided by said ink reservoir positioned above said chamber.
8. The printer of claim 1 , wherein said valve stem is positioned between said pivot and said float.
9. The printer of claim 1 , wherein said inlet port and said outlet port are positioned towards a base of said chamber.
10. The printer of claim 1 , wherein said chamber comprises a return port, said return port being connected to an ink outlet of said printhead via a downstream ink line.
11. The printer of claim 10 , wherein said return port comprises an inline ink filter.
12. The printer of claim 1 , wherein said air vent comprises an air permeable membrane, which is impervious to ink.
13. The printer of claim 1 , wherein said printhead is a stationary pagewidth printhead.