Inkjet printhead with small nozzle spacing
View Patent ↗An ink jet printhead with an array of nozzles unit cells 1 . Each of the unit cells having one or more heaters 10 configured to form a gas bubble 12 in ejectable liquid held in the nozzle chamber. The generation of the bubble 12 causes the ejection of a drop 16 of an ejectable liquid (such as ink) through an ejection aperture 5 in each nozzle 3 , to effect printing. The nozzle unit cells 1 are manufactured using semiconductor and micro mechanical techniques such that the spacing between adjacent nozzle apertures 5 in the printhead is less than 100 microns. With the use of semiconductor and micro mechanical manufacturing techniques, the dimension of the nozzles structures can be kept relatively small without significant increases in manufacturing costs. Therefore, the nozzle density in the printhead can be increased for greater printing resolution.
1. An inkjet printhead comprising:
a plurality of nozzle unit cells, each of the nozzle unit cells having a nozzle aperture formed in a common nozzle plate, a nozzle chamber for holding ejectable liquid, a plurality of heaters and associated drive circuitry, each heater having at least one planar heater element suspended in the nozzle chamber, the heater elements within each chamber being formed on different respective planes parallel to the common nozzle plate to one another, the heater element being configured for generating a gas bubble in the ejectable liquid that ejects a drop of the ejectable liquid from the nozzle, the heater element having top and bottom opposite planar sides and is configured such that the gas bubble is formed at both of said sides wherein,
adjacent nozzle apertures are less than 80 microns apart.
2. A printhead according to claim 1 wherein the nozzle unit cells are formed in a generally planar array, each cell being less than 40 microns wide and less than 70 microns long with respect to the plane of the array.
3. A printhead according to claim 1 wherein a silicon wafer provides a support substrate for the array of the nozzle unit cells, the unit cells being formed on one side of the wafer; wherein,
a plurality of liquid supply passages extend from the opposing side of the wafer to each of the nozzle unit cells respectively, the liquid passages extending substantially normal to the plane of the array.
4. A printhead according to claim 1 wherein the heater has a heater element suspended in the chamber such that during use it is immersed in the ejectable liquid.
5. A printhead according to claim 1 being configured to be a pagewidth printhead.
6. A printhead according to claim 1 wherein the heater is in the form of a cantilever beam.
7. A printhead according to claim 1 wherein the heater is configured such that an actuation energy of less than 500 nanojoules (nJ) is necessary to heat the heater sufficiently to form the bubble that ejects the drop.
8. A printhead according to claim 1 wherein during use the ejectable liquid enters the chamber at an ambient temperature, and the energy required by the heater to generate the gas bubble to eject the drop, is less than the energy required to heat a volume of the ejectable liquid equal to the volume of the drop, from a temperature equal to the ambient temperature to the ejectable liquid's boiling point.
9. A printhead according to claim 1 further comprising a substrate having a substrate surface, wherein the areal density of the nozzles relative to the substrate surface exceeds 10,000 nozzles per square cm of substrate surface.
10. A printhead according to claim 1 wherein the bubble has a point of collapse spaced from the heater.
11. A printhead according to claim 1 further comprising a structure that is formed by chemical vapor deposition (CVD), the nozzles being incorporated on the structure.
12. A printhead according to claim 1 further comprising a structure which is less than 10 microns thick, the nozzles being incorporated on the structure.
13. A printhead according to claim 1 wherein the heater is formed of solid material more than 90% of which, by atomic proportion, is constituted by at least one periodic element having an atomic number below 50.
14. A printhead according to claim 1 wherein each of the heaters has a heater element, the heater element includes solid material and is configured for a mass of less than 10 nanograms.
15. A printhead according to claim 1 wherein each of the heaters has a heater element, the heater element is substantially covered by a conformal protective coating, the coating of each of the heater element having been applied substantially to all sides of the heater element simultaneously such that the coating is seamless.