Inkjet printer with selectively isolatable pump
View Patent ↗An inkjet printer that has a printhead for printing onto a media substrate, a reservoir for supplying ink to the printhead, a pump for drawing ink from the reservoir and pumping ink into the printhead and, a valve arrangement for selectively opening fluid communication between the pump and the printhead, and closing fluid communication between the pump and the printhead while opening fluid communication between the reservoir and the printhead.
1. An inkjet printer comprising:
a printhead for printing onto a media substrate;
a reservoir for supplying ink to the printhead;
a pump for drawing ink from the reservoir and pumping ink into the printhead; and,
a valve arrangement for selectively opening fluid communication between the pump and the printhead, and closing fluid communication between the pump and the printhead while opening fluid communication between the reservoir and the printhead,
wherein the valve arrangement is configured such that the pump is not in fluid communication with the reservoir whenever the pump is in fluid communication with the printhead.
2. An inkjet printer according to claim 1 further comprising a filter for ink flowing from the pump to the printhead, the filter being positioned such that it is not in fluid communication with the printhead when the valve arrangement is configured for fluid communication between the reservoir and the printhead.
3. An inkjet printer according to claim 1 wherein the valve arrangement is configured such that the pump is not in fluid communication with the reservoir whenever the reservoir is in fluid communication with the printhead.
4. An inkjet printer according to claim 3 further comprising an upstream line for establishing fluid communication between the reservoir and the printhead wherein the valve arrangement is a three-way valve in the upstream line and the pump connects to the three-way valve via a branch line, the three way valve having three settings; a first setting connecting the upstream line to the reservoir to the upstream line to the printhead while closing the branch line, a second setting connecting the branch line to the upstream line to the reservoir while closing the upstream line to the printhead, and a third setting connecting the branch line to the upstream line to the printhead while closing the upstream line to the reservoir.
5. An inkjet printer according to claim 1 wherein the pump has a chamber with a reciprocating plunger.
6. An inkjet printer according to claim 1 wherein the pump is a bulb of elastomeric material for holding a volume of ink and an actuator for selectively compressing the bulb.
7. An inkjet printer according to claim 1 wherein the reservoir has a pressure regulator for establishing a predetermined pressure in a headspace above the ink in the reservoir, the predetermined pressure being less than atmospheric pressure.
8. An inkjet printer according to claim 7 wherein the pump draws ink from the reservoir to reduce the pressure in the headspace to the predetermined pressure in preparation for printing.
9. An inkjet printer according to claim 8 wherein the ink drawn from the reservoir by the pump in preparation for printing is pumped into the printhead in preparation for printing.
10. An inkjet printer according to claim 1 wherein the printhead has a distribution manifold and a plurality of printhead integrated circuits mounted to the distribution manifold such that priming the distribution manifold with ink also primes the printhead integrated circuits.