Abstract: An ink jet head has coaxially disposed inner and outer cylindrical tubes with the outer cylindrical surface of the inner cylindrical tube spaced from the inner cylindrical surface of the outer cylindrical tube to form an ink cavity therebetween from which ink is supplied through one or more arrays of ink jet nozzles. Only the outer tube is a piezoelectric material so that the outer tube vibrates radially when electrically excited to produce vibrations in the ink in the ink cavity whereby a stream of ink droplets is supplied from each of the ink jet nozzles. In embodiments having only multiple arrays of ink jet nozzles, if desired, only the inner cylindrical tube or both the inner and outer cylindrical tubes can be formed of a piezoelectric material. If both of the tubes are formed of a piezoelectric material, the operating frequencies, which are preferably resonant, of the two tubes must then be matched.

Abstract: A multi-nozzle electrostatic ink jet head for producing streams of ink drops for selective deposition on a record medium, arranged orthogonal to the direction of relative head-to-medium motion, having plural rows of nozzles and corresponding charge electrodes arranged on the diagonal with respect to the relative motion, and having common deflection electrodes for all streams.