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