Inkjet printhead with non-uniform width ink supply passage to nozzle
View Patent ↗An inkjet printhead with nozzles 4 and liquid passages 31, 32 leading to each nozzle. The nozzles, ejection actuators 14 , associated drive circuitry 22 and liquid passage 31, 32 being formed on and through a wafer 21 using lithographically masked etching technique, such that the wafer has a droplet ejection side and a liquid supply side. Each of the liquid passages is formed by etching a hole 31 partially through the wafer 21 from the droplet ejection side, and etching a passage from the liquid supply side of the wafer 21 to the hole 31 . Etching a hole 31 into the wafer 21 from the droplet ejection side means the ink supply passage 32 can stop short of the interface between the dielectric 23 and the wafer 21 . The plasma does not get the opportunity to track along the interface and damage the drive semiconductors. By making the liquid supply passage 32 wider than the hole 31 to account for the inherent tolerances of the etching process, a suitable fluid connection is assured. As the hole etched from the ejection side is relatively shallow, the removal of the resist is not overly difficult. This permits a more compact overall design and higher nozzle packing density.
1. An inkjet printhead comprising:
a monolithic wafer having a droplet ejection side and a liquid supply side;
a plurality of nozzles formed in a planar array parallel to the droplet ejection side;
a plurality of droplet ejection actuators and associated drive circuitry corresponding to each nozzle respectively, the ejection actuators being formed in respective nozzle chambers on the droplet ejection side such that each of the nozzles is in fluid communication with one of the chambers respectively, the chambers being formed between the drive circuitry and the planar array of nozzles; and,
a plurality of liquid passages extending from each of the chambers respectively to the liquid supply side for supply each of the nozzles with liquid; wherein,
each of the liquid passages is formed by a hole extending from the respective chamber, through the drive circuitry and into the monolithic wafer, and a supply passage extending from the liquid supply side partially through the monolithic wafer such that a fluid connection is established with the hole, the supply passage and the chamber being wider than the hole.
2. An inkjet printhead according to claim 1 wherein the width of the hole is between 8 microns and 24 microns.
3. An inkjet printhead according to claim 1 wherein the width of the supply passage is between 10 microns and 28 microns.
4. An inkjet printhead according to claim 1 wherein the droplet ejection actuators are thermal bend actuators.
5. An inkjet printhead according to claim 1 wherein the droplet ejection actuators are gas bubble generating heater elements.
6. An inkjet printhead according to claim 1 wherein the bubble forming liquid is the same as the ejected liquid.
7. An inkjet printhead according to claim 1 wherein the printhead is a pagewidth printhead.