| 摘要 |
A spot size modulatable, drop-on-demand type ink jet printhead (2) for producing grey-scale images on a substrate. The ink jet printhead (2) includes a main body portion (14) having an ink-carrying channel (6) extending therethrough and a piezoelectric actuator (34) coupled to the ink-carrying channel (6). A spot size for droplets to form when striking the substrate after ejection from the ink-carrying channel (6) is selected and a look-up table (54) translates the selected spot size into a time period during which a voltage pulse is to be applied to the piezoelectric actuator (34) by an associated switching structure (62) to initiate application of the voltage waveform, determines whether the voltage waveform has been applied to the piezoelectric actuator (34) for the time period and terminates application of the voltage waveform upon expiration of the time period. The control circuit includes a sequencer (60) which selectively asserts or deasserts at least one control signal to the switching structure, a timer (52) which instructs the sequencer (60) to initiate application of the voltage waveform and determines time elapsed since initiating application, and a comparator (58) which compares the time period produced by the look-up table (54) and the elapsed time determined by the timer (52). |
