MULTI-CHANNEL DIAPHRAGM VALVE FOR PRINTHEAD

1 . A multi-channel diaphragm valve for distributing ink from a plurality of ink supplies to a media width inkjet printhead via a plurality of ink flow channels, the valve comprising:

a body;

a plurality of sealed chambers within the body;

a plurality of groups of ports on the body, each port group being associated with a respective one of the chambers and having individual ports for respective connection to the printhead and a respective one of the ink supplies; and

a plurality of diaphragm pads having seals for sealing respective ones of the ports; and

a selection device for manipulating the diaphragm pad to selectively seal and un-seal the ports to establish interconnection between the ports of each port group to allow ink flow therebetween for each of the channels.

2 . A valve according to claim 1 , wherein five ink channels are provided between five ink supplies and the printhead, the valve comprising five of the sealed chambers and five associated port groups.

3 . A valve according to claim 1 , wherein the selection device comprises a driven shaft and selection members on the shaft, the selection members being rotated by driven rotation of the shaft so as to manipulate the diaphragm pads.

4 . A valve according to claim 3 , wherein the selection members comprise eccentric cams mounted on the shaft.

5 . A valve according to claim 4 , wherein the selection members comprises cantilevered fingers mounted within the body so that each finger is aligned with a respective one of the eccentric cams.

6 . A valve according to claim 5 , wherein the diaphragm pads are arranged so that rotation of the eccentric cams selectively presses the fingers into and out of contact with the diaphragm pads thereby discretely deforming the diaphragm pads to seal and un-seal the ports.

7 . A valve according to claim 4 , further comprising sealing films sealingly located between the respective diaphragm pads and fingers.

8 . A valve according to claim 5 , wherein a plurality of groups of the eccentric cams are arranged so that each cam group corresponds to a port group, the cams of each group being arranged so that eccentric features of the cams are offset relative to each other cam in that group and are aligned to a corresponding cam in each other cam group.

9 . A valve according to claim 1 , wherein each port group comprises a first port for connection to the ink source, a second port for connection to the printhead, a third port for connection to a bypass ink path which bypasses the printhead on the respective ink flow channel, and a fourth port for connection to a gas vent on said ink flow channel.

10 . A valve according to claim 9 , wherein:

each ink flow channel comprises a first path between the ink source and one longitudinal end of the media width of the printhead and a second path between the ink source and the other longitudinal end of the media width of the printhead;

each bypass path bridges across the printhead between the first and second paths of the respective ink flow channel; and

the valve is configured to be located on the first path of each ink flow channel.

11 . A valve according to claim 10 , wherein each ink flow channel and bypass path comprise fluid hoses, the first, second, third and fourth ports being configured to connect with the fluid hoses.