Patent ID: 7178893

Claim:
A head controller for controlling pressure creating means for contracting and expanding a volume of a pressurizing compartment communicating with a nozzle of a droplet discharging head, comprising: drive waveform generating means for outputting a drive pulse that includes at least a first waveform element for expanding the volume of said pressurizing compartment, a second waveform element for maintaining an expanded state of the volume of said pressurizing compartment caused by the first waveform element, and a third waveform element for contracting the volume of said pressurizing compartment in the expanded state so that droplets are discharged from said pressurizing compartment; and means for decreasing a difference between first and second potential differences when environmental temperature is higher than a first predetermined temperature and increasing the difference between the first and second potential differences when the environmental temperature is lower than a second predetermined temperature, wherein the first potential difference is a potential difference between the first waveform element at the beginning of expansion of the volume of said pressurizing compartment and the second waveform element, and the second potential difference is a potential difference between the third waveform element at the end of contraction of the volume of said pressurizing compartment and the second wave form element, and wherein the drive waveform generating means is configured to generate and output a drive waveform having the first potential difference greater than the second potential difference, and configured to vary a potential of the first waveform element according to the environmental temperature without varying a potential of the third waveform element.