Drop on demand ink jet technology is widely used in the printing industry. Printers using drop on demand ink jet technology can use either thermal ink jet technology or piezoelectric technology. Even though they are more expensive to manufacture than thermal ink jets, piezoelectric ink jets are generally favored as they can use a wider variety of inks and eliminate problems with kogation.
Piezoelectric ink jet print heads typically include a flexible diaphragm and a piezoelectric element attached to the diaphragm. When a voltage is applied to the piezoelectric element, typically through electrical connection with an electrode electrically coupled to a voltage source, the piezoelectric element deflects causing the diaphragm to flex toward a nozzle (aperture or jet) which increases pressure within an ink chamber and expels a quantity of ink from the chamber through the nozzle. As the diaphragm returns to a relaxed state, it flexes away from the nozzle which decreases pressure within the chamber and draws ink into the chamber from a main ink reservoir through an opening to replace the expelled ink.
Increasing the printing resolution of an ink jet printer employing piezoelectric ink jet technology is a goal of design engineers. Increasing the jet density of the piezoelectric ink jet print head can increase printing resolution. One way to increase the jet density is to eliminate manifolds which are internal to a jet stack. With this design, it is preferable to have a single port through the back of the jet stack for each jet. The port functions as a pathway for the transfer of ink from the reservoir to each ink jet chamber. Because of the large number of jets in a high density print head, the large number of ports, one for each jet, must pass vertically through the diaphragm and between the piezoelectric elements.
Manufacturing a high density ink jet print head assembly having an external manifold has required new processing methods. Methods for manufacturing a print head which use less equipment, fewer processing stages, and reduced materials, and the print head resulting from the method, would be desirable.