Spot size modulation using multiple pulse resonance drop ejection

A drop-on-demand ink jet printing system comprising an ink jet head having an ink cavity, an orifice communicating with said ink cavity, and an electromechanical transducer mounted in mechanical communication with said ink cavity, a source of electrical drive signals repeatable at a predetermined drop-on-demand drop production rate, and means to selectively actuate said electromechanical transducer in response to said electrical drive signals to force a single drop of ink from said orifice;

• the improvement comprising;
• means for selectively producing at least one additional electrical drive signal each with a fixed time delay with respect to the immediately preceding electrical drive signal, said fixed time delay being short with respect to said drop-on-demand drop production rate;
• and
• means to actuate said electromechanical transducer with each of said electrical drive signals to produce a quantity of ink having a predetermined volume from said orifice, said quantities of ink merging into a single drop of ink prior to the time the drop reaches the print medium for printing whereby each ink drop can be produced having a selected one of a plurality of possible drop sizes.