CA2263782C - Simplified ink jet head - Google Patents

Abstract

In the embodiments of the simplified ink jet head described in the specification, a carbon body is formed with ink passages, such as internal passages (19, 21, 25) extending through a carbon plate (26), pressure chambers (2) on one side of a carbon plate (26), flow-through passages (24) on the other side of the same plate and ink supply passages (19, 25), and a piezoelectric plate (23) is affixed to the pressure chamber side of the carbon plate by a thin layer of epoxy adhesive. The piezoelectric plate (23) may have a conductive coating on one side which is photo-etched to produce an electrode pattern corresponding to the pattern of the pressure chambers in the carbon plate. An orifice plate (13) may have specially profiled orifice openings (12) to assure axial projection of drops and may be affixed by a thin layer of epoxy adhesive to a carbon plate (26) having orifice passages (21) supplying ink from the pressure chambers (20) to the orifices (12). Since the carbon plate is conductive, it can be used, if desired, as an electrode on the opposite side of the piezoelectric plate (23) and, to assure grounding of the piezoelectric plate, a conductive epoxy adhesive may be used to bond the piezoelectric plate to the carbon plate. Moreover, since the carbon plate is porous, it can provide a communication path (76) between a vacuum source (77) and an air-permeable, ink-impermeable layer (75) on the ink passages to remove dissolved air from the ink in the passages. In one alternative embodiment, an ink jet head assembly contains two separate carbon pressure chamber plates, a carbon manifold plate and a carbon collar to retain the carbon plates in an assembly.

Claims (2)

The embodiments of the invention in which. an exclusive property or privilege is claimed are defined as follows:

1. An orifice plate for an ink jet head comprising a metal plate having parallel inner and outer planar surfaces and an array of orifices extending between the inner and outer surfaces wherein each of the orifices has a cylindrical ink outlet portion having a diameter and extending inwardly from the outer surface of the plate, a cylindrical ink inlet portion extending inwardly from the inner surface of the plate having a larger diameter than the diameter of the ink outlet portion, and a tapered conical portion joining the ink inlet portion and the ink outlet portion and having a surface farmed in the shape of a cone generated by the hypotenuse of a right triangle rotated about one of its legs as an axis and wherein. the ink inlet portion Yeas a length greater than the length of the ink outlet portion, whereby improved axial projection of ink drops is obtained with ink supplied from an asymmetric ink path leading to the orifice.

2. An orifice plate according to claim 1 wherein the diameter of the ink: inlet portion is no more than about twice the diameter of the ink outlet portion.