Inkjet nozzle with individual ink feed channels etched from both sides of wafer
View Patent ↗An array of ink ejection nozzles formed on a wafer substrate by lithographic etching and deposition techniques, each nozzle having a chamber with an actuator for ejecting drops of ink through the nozzle, and an ink inlet in fluid communication with the ejection nozzle; and, a plurality elongate ink feed channels connected to each of the ink inlets respectively; wherein, the ink inlet is etched from one side of the wafer and the ink feed channels are etched from the opposite side of the wafer. By etching long ink feed channels for each nozzle eliminates fluidic cross talk between adjacent nozzles. An ink feed channel that supplies several nozzles needs to incorporate special features such as pinch points to deal with fluidic cross talk. The ink can be supplied from the ‘back’ surface of the wafer, thereby removing the need for ink feed channels beside the chambers. This provides more room for the power and print data to be connected to each nozzle along the front surface of the wafer.
1. An inkjet drop ejection apparatus comprising: an array of ink ejection nozzles formed on a front surface of a wafer substrate, each nozzle having a chamber with an actuator for ejecting drops of ink through the nozzle, and an ink inlet in fluid communication with the ejection nozzle, the actuator having an ink engaging surface, a movable structure and a heater, the movable structure connected to the wafer substrate and the ink engaging surface, the heater being positioned to heat one part of the movable structure more than another part thereby moving the movable structure by differential thermal expansion and consequently displace the ink engaging surface within the chamber; and a plurality elongate ink feed channels connected to each of the ink inlets respectively; wherein, said actuator is a bend actuator cantilevered into the chamber from a fixed end, wherein a region closest to the fixed end flexes more readily than the remainder of said actuator.
2. An inkjet drop ejection apparatus as claimed in claim 1 further comprising drive circuitry for each of the actuators wherein the ink inlet extends into the wafer at least 20 microns passed the drive circuitry.
3. An inkjet drop ejection apparatus as claimed in claim 1 wherein the ink feed channel is wider than the ink inlet.
4. An inkjet drop ejection apparatus as claimed in claim 1 wherein the ink feed channel is etched and the wafer is diced into separate chips by a single dry etching process.
5. An inkjet drop ejection apparatus as claimed in claim 1 wherein during use, activation of said actuator supplies sufficient kinetic energy to the ink in the chamber to expel a drop of ink from said nozzle.
6. An inkjet drop ejection apparatus as claimed in claim 1 wherein said actuator is capable of directly firing the ink drops from said nozzle, without the assistance of an external field.
7. An inkjet drop ejection apparatus as claimed in claim 1 wherein said actuator is a differential expansion bend actuator capable of converting a high force, low travel mechanism to high travel, lower force mechanism.
8. An inkjet drop ejection apparatus as claimed in claim 1 wherein the chamber, the actuator and the nozzle are configured such that ink refills the chamber after drop ejection by the surface tension of the ink.
9. An inkjet drop ejection apparatus as claimed in claim 1 wherein the nozzle is formed in a surface deposited as a layer using VLSI deposition techniques, wherein the nozzle is etched in said surface.