Inkjet thermal actuator with parallel current paths
View Patent ↗An inkjet printhead is disclosed. The printhead has an array of ink chambers. Each ink chamber has a nozzle and a thermal actuator for generating vapor bubbles to eject ink through the nozzle. The thermal actuator has a pair of contacts and at least two parallel current paths between the contacts. Each of the current paths has a plurality of heater elements for nucleating a vapor bubble.
1. An inkjet printhead comprising an array of ink chambers, each ink chamber comprising:
a plurality of nozzles; and
a thermal actuator for generating vapour bubbles to eject ink through the nozzles, the thermal actuator comprising a pair of contacts and at least two parallel current paths between the contacts, each of the current paths having a plurality of heater elements connected in series, wherein the heater elements are suspended within the chamber.
2. An inkjet printhead according to claim 1 , wherein respective heater elements are associated with respective nozzles.
3. An inkjet printhead according to claim 1 wherein the heater elements nucleate bubbles simultaneously.
4. An inkjet printhead according to claim 1 wherein the thermal actuator has a cross bracing structure extending between intermediate points on the parallel current paths.
5. An inkjet printhead according to claim 4 wherein the cross bracing structure provides increased thermal inertia to the current paths where the cross bracing structure connects to the current paths.
6. An inkjet printhead according to claim 4 wherein the cross bracing structure provides a droplet stem anchor.
7. An inkjet printhead according to claim 1 wherein the thermal actuator is formed from TiAlN.
8. An inkjet printhead according to claim 1 wherein each of the ink chambers has two nozzles.
9. An inkjet printhead according to claim 1 wherein the nozzles in each chamber are arranged in a line parallel to the length of the heater element, with the central axes of the nozzles being regularly spaced along the heater element.
10. An inkjet printhead according to claim 1 wherein the nozzles are elliptical.
11. An inkjet printhead according to claim 10 wherein the major axes of the elliptical nozzles are aligned.