Abstract: A piezoelectric ink jet printing module has a semiconductive material on a surface of a piezoelectric element of the module.

Abstract: A piezoelectric ink jet printing module has a semiconductive material on a surface of a piezoelectric element of the module.

Abstract: A piezoelectric ink jet printing module has a semiconductive material on a surface of a piezoelectric element of the module.

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 extending through a carbon plate, pressure chambers on one side of a carbon plate, flow-through passages on the other side of the same plate and ink supply passages, and a piezoelectric plate is affixed to the pressure chamber side of the carbon plate by a thin layer of epoxy adhesive. The piezoelectric plate 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 may have specially profiled orifice openings to assure axial projection of drops and may be affixed by a thin layer of epoxy adhesive to a carbon plate having orifice passages supplying ink from the pressure chambers to the orifices.

Abstract: In the method and apparatus for printing bar codes on cartons disclosed in the specification, cartons on which bar codes are to be printed are conveyed in succession in either direction past a heater which heats a selected portion of the carton surface and a hot melt ink jet printer which prints a bar code on the heater portion of the bar code surface. The carton surface portion is heated to a temperature which is above ambient temperature by an amount which is equal to about 40% to 100% of the difference between ambient temperature and the solidification temperature of the hot melt ink.

Abstract: In the simplified ink jet head described in the specification, a tubular member made of air-permeable, ink-permeable material which is closed at one end and connected at the other end to a source of subatmospheric pressure is inserted into an ink passage in the ink jet head to extract dissolved air through the material of the tubular member from a surrounding body of ink in the ink passage.

Abstract: In the embodiments of the simplified ink jet head described in the specification an orifice plate has specially profiled orifice openings to assure axial projection of drops when ink is supplied from an asymmetric ink path leading to the orifice. For this purpose the orifice includes cylindrical ink inlet and outlet portions with the ink outlet portion having a smaller diameter and a shorter length than the inlet portion and a tapered conical portion joining the ink inlet portion and the ink outlet portion. Preferably, the diameter of the inlet portion is no more than about twice the diameter of the outlet portion.

Abstract: In the embodiments described in the specification, a ceramic piezoelectric plate is polarized by compressing the plate between electrode plates with intervening slightly conductive rubber sheets or by applying electric charge from a corona discharge device to one surface of the plate while the opposite surface is grounded until the applied charge is sufficient to create a breakdown.