Inkjet printhead with nozzle assemblies having raised meniscus-pinning rims
View Patent ↗An ink jet printhead has a wafer substrate incorporating CMOS drive circuitry. A plurality of nozzle assemblies is arranged in an array on the substrate and is the product of dielectric and metal layers deposited on the wafer substrate and etched, such that the wafer substrate and layers define ink inlet apertures. Each nozzle assembly has a wall portion bounding a respective ink inlet aperture. A crown portion defines a nozzle opening. A skirt portion depends from the crown portion to form part of a peripheral wall of the nozzle assembly. The crown and skirt portions are displaceable with respect to the wall portion to alter a volume of a nozzle chamber defined by the wall, crown and skirt portions such that when the volume is altered, ink is ejected from the nozzle opening. A thermal actuator interconnects the crown and skirt portion with the substrate and is connected to the drive circuitry to displace the crown and skirt portions on receipt of an electrical signal from the drive circuitry. The crown portion defines a raised rim that surrounds the nozzle opening to facilitate the formation of a meniscus of ink.
1. An inkjet printhead which comprises
a wafer substrate incorporating CMOS drive circuitry; and
a plurality of nozzle assemblies arranged in an array on the substrate and the product of dielectric and metal layers deposited on the wafer substrate and etched, such that the wafer substrate and layers define ink inlet apertures, each nozzle assembly comprising
a wall portion bounding a respective ink inlet aperture;
a crown portion that defines a nozzle opening;
a skirt portion depending from the crown portion to form part of a peripheral wall of the nozzle assembly, the crown and skirt portions being displaceable with respect to the wall portion to alter a volume of a nozzle chamber defined by the wall, crown and skirt portions such that when the volume is altered, ink is ejected from the nozzle opening; and
a thermal actuator that interconnects the crown and skirt portion with the substrate and is connected to the drive circuitry to displace the crown and skirt portions on receipt of an electrical signal from the drive circuitry, wherein
the crown portion defines a raised rim that surrounds the nozzle opening to facilitate the formation of a meniscus of ink.
2. An ink jet printhead as claimed in claim 1 , in which the dielectric layer is a chemical vapor deposition (CVD) oxide.
3. An ink jet printhead as claimed in claim 1 , wherein the metal layer is aluminum.
4. An ink jet printhead as claimed in claim 1 , wherein the passivation layer is a CMOS layer.
5. An ink jet printhead as claimed in claim 1 , wherein the passivation layer includes a plasma-enhanced chemical vapor deposition (PECVD) nitride.
6. An ink jet printhead as claimed in claim 1 , wherein the sacrificial layers are formed from a photo-sensitive polyimide or high temperature resist, individually or in combination.
7. An ink jet printhead as claimed in claim 1 , in which the wall portion and skirt portion are configured to define a fluidic seal to inhibit the egress of ink during relative displacement.