Techniques for improving droplet uniformity in acoustic ink printing

Abstract

Techniques for improving droplet uniformity in acoustic ink printing. Row to row variations in an average droplet characteristic are reduced by controlling the electric power applied to the droplet ejectors of the individual rows. By applying the proper power to each row, the average droplet characteristic from the individual rows are made substantially. Another technique varies the efficiency of the individual droplet ejectors by physically trimming (such as with a laser) one or more of its components. Trimming may be performed on a droplet ejector's transducer, varactor, one or more associated resistors, or one or more capacitors. Yet another technique controls droplet ejector efficiency by electrically controlling the capacitance of a varactor associated with each droplet ejector, and thus each droplet ejector's efficiency. The voltage applied to each varactor may be controlled as a function of its column (to improve column to column uniformity), row (to improve row to row uniformity) or as a function of its column and row (to control the efficiency of the individual droplet ejector).