Inkjet printhead with bubble trap and air vents
View Patent ↗An inkjet printhead that has an array of ink chambers arranged to remove air bubbles entrained in the ink supply flow. Each of the ink chambers has a nozzle and a thermal actuator respectively, the array of ink chambers defined by sidewalls extending between a nozzle plate and an underlying wafer substrate. The printhead also has ink inlets extending through the underlying wafer substrate. Each of the ink inlets has an ink permeable trap and a vent sized such that the surface tension of an ink meniscus across the vent prevents ink leakage. The ink permeable trap has columns extending from the underlying wafer substrate to the vent to direct gas bubbles entrained in a flow of ink through the ink inlet towards the vent.
1. An inkjet printhead comprising:
an array of ink chambers, each having a nozzle and a thermal actuator respectively, the array of ink chambers defined by sidewalls extending between a nozzle plate and an underlying wafer substrate; and,
a plurality of ink inlets extending through the underlying wafer substrate, each of the ink inlets having an ink permeable trap and a vent sized such that the surface tension of an ink meniscus across the vent prevents ink leakage; wherein,
the ink permeable trap has columns extending from the underlying wafer substrate to the vent to direct gas bubbles entrained in a flow of ink through the ink inlet towards the vent.
2. The inkjet printhead according to claim 1 wherein the ink chambers are positioned such that refill ink flows through one of the ink chambers to another of the ink chambers after ejection of ink through the corresponding nozzles.
3. The inkjet printhead according to claim 1 wherein each of the ink chambers has a plurality of nozzles; wherein during use,
the thermal actuator simultaneously ejects ink through all the nozzles of the chamber.
4. The inkjet printhead according to claim 1 further comprising at least one priming feature extending through each of the ink inlets; such that,
the surface tension of an ink meniscus at the ink inlet acts to draw the ink out of the inlet and partially along the flow path toward the ink chambers.
5. The inkjet printhead according to claim 1 wherein the ink chambers have an elongate shape such that two of the sidewalls are long relative to the others, and the opening for allowing ink to refill the chamber is in one of the long sidewalls.
6. The inkjet printhead according to claim 1 further comprising a filter structure at the opening of each ink chamber, the filter structure having rows of obstructions extending transverse to the flow direction through the opening, the obstructions in each row being spaced such that they are out of registration with the obstructions in an adjacent row with respect to the flow direction.
7. The inkjet printhead according to claim 1 wherein the nozzles are arranged in rows such that the nozzle centres are collinear and the nozzle pitch along each row is greater than 1000 nozzles per inch.
8. The inkjet printhead according to claim 1 wherein the nozzle plate has an exterior surface with formations for reducing its coefficient of static friction.
9. The inkjet printhead according to claim 2 further comprising a plurality of ink conduits between the nozzle plate and the underlying wafer, each of the ink conduits establishing fluid communication between at least one of the ink inlets and a plurality of the ink chambers.
10. The inkjet printhead according to claim 3 wherein the thermal actuator has a plurality of heater elements, one of the heater elements corresponding to each of the nozzles respectively.
11. The inkjet printhead according to claim 9 further comprising drive circuitry for providing a drive signal to the thermal actuators for ejecting ink through the corresponding nozzle, the drive circuitry having a plurality of separate drive circuits such that during use each of the drive circuits simultaneously powers a plurality of the thermal actuators.
12. The inkjet printhead according to claim 9 wherein each of the ink conduits is in fluid communication with two of the ink inlets.
13. The inkjet printhead according to claim 10 wherein the heater elements are configured as elongate strips, the nozzles in each chamber being arranged in a line parallel to that of the longitudinal extent of the heater element.
14. The inkjet printhead according to claim 11 wherein the plurality of actuators that simultaneously activate are connected in series.
15. The inkjet printhead according to claim 11 wherein the drive circuitry has a plurality of field effect transistors (FETs), each of the FETs configured to provide respective thermal actuators with the drive signal.
16. The inkjet printhead according to claim 13 wherein the nozzles are elliptical.
17. The inkjet printhead according to claim 15 wherein each of the FETs has a source-drain voltage of less than 5 Volts.
18. The inkjet printhead according to claim 16 wherein the major axes of the elliptical nozzles are aligned.