Droplet propelling device

A droplet propelling device adapted to propel droplets of ink through a nozzle, the droplet propelling device comprising:

• a pressure regulator configured to cause changes in volume of an ink chamber communicating with the nozzle to make increases and decreases in pressure of ink in the ink chamber;
• and
• a driver configured to generate a drive signal, and use the drive signal to drive the pressure regulator, the drive signal having a satellite controlling waveform including a first swelling pulse adapted to serve for use of the pressure regulator to cause an increase in volume of the ink chamber for a constant period, a second swelling pulse adapted to serve after an end of the first swelling pulse, interposing a prescribed interval in between, for use of the pressure regulator to cause another increase in volume of the ink chamber for a constant period, and a contracting pulse adapted to serve after an ‘off’ of the second swelling pulse for use of the pressure regulator to cause a decrease in volume of the ink chamber for a constant period, wherein
• the driver is configured to turn the second swelling pulse on in a first period that is a period from a first positive pressure peak being a peak of increase in pressure of ink in the ink chamber caused by the first swelling pulse turned on or off to a first negative pressure peak being a peak of decrease in pressure of ink ensuing therefrom, and turn the second swelling pulse off in a second period that is a period from the first negative pressure peak to a second positive pressure peak being a peak of increase in pressure of ink ensuing therefrom, and
• the driver is configured to work in the second period to turn the contracting pulse on after an off of the second swelling pulse, and turn the contracting pulse off in a period for restoration in pressure of ink in the ink chamber from the second positive pressure peak to a normal pressure value.