Nozzle arrangement for an inkjet printhead with ink passivation structure
View Patent ↗A nozzle arrangement for an inkjet printhead includes a wafer substrate defining an ink passage and incorporating drive circuitry. A passivation layer is operatively positioned on the substrate and defines a first aperture of lesser cross sectional area than the ink passage and which is in fluid communication with the ink passage. A nozzle chamber wall extends from the passivation layer. A nozzle chamber roof is positioned on the nozzle chamber wall so as to define a nozzle chamber that is in fluid communication with the first aperture. The roof defines an ejection port that is in fluid communication with the nozzle chamber and the wall defines a second aperture. An actuator is anchored to the passivation layer, extends through the second aperture and terminates in a paddle. The actuator is connected to the drive circuitry and is configured so that, upon receipt of a drive signal from the drive circuitry, the actuator displaces the paddle to eject ink through the ejection port.
1. A nozzle arrangement for an inkjet printhead, the nozzle arrangement comprising:
a wafer substrate defining an ink passage and incorporating drive circuitry;
a passivation layer operatively positioned on the substrate and defining a first aperture of lesser cross sectional area than the ink passage and which is in fluid communication with the ink passage;
a nozzle chamber wall extending from the passivation layer;
a nozzle chamber roof positioned on the nozzle chamber wall so as to define a nozzle chamber that is in fluid communication with the first aperture, the roof defining an ejection port that is in fluid communication with the nozzle chamber and the wall defining a second aperture; and
an actuator anchored to the passivation layer, extending through the second aperture and terminating in a paddle, the actuator being connected to the drive circuitry and being configured so that, upon receipt of a drive signal from the drive circuitry, the actuator displaces the paddle to eject ink through the ejection port.
2. A nozzle arrangement as claimed in claim 1 , wherein the ink passage, first aperture and ejection port are co-incident with a common axis.
3. A nozzle arrangement as claimed in claim 1 , wherein the actuator is a thermal actuator configured to undergo differential thermal expansion and contraction on receipt of the drive signal to result in displacement of the paddle.
4. A nozzle arrangement as claimed in claim 3 , in which the drive circuitry is defined by a CMOS layer positioned on the substrate and electrically coupled to the actuator.
5. A nozzle arrangement as claimed in claim 4 , wherein the actuator includes a pair of spaced actuating members, one of the members being an active member and the other being a passive member, with one of the members being interposed between the substrate and the other member and the active member defining a heating circuit connected to the drive circuitry to be heated by an electrical signal from the drive circuitry, at least said active member being of a material having a coefficient of thermal expansion which permits that actuating member to perform work upon expansion.
6. A nozzle arrangement as claimed in claim 5 , wherein the active member is connected to the CMOS layer while the passive member is insulated from the CMOS layer.
7. A nozzle arrangement as claimed in claim 1 , wherein the passivation layer is formed from silicon nitride.