Patent ID: 8721053

Claim:
A liquid droplet discharge head comprising: a liquid chamber to which a liquid is supplied; a plurality of nozzles from which the liquid is discharged; a diaphragm to change a pressure inside the liquid chamber; a piezoelectric element to displace the diaphragm; a drive voltage generator to generate a discharge pulse voltage to drive the piezoelectric element to discharge liquid droplets from the nozzles; a micro-drive voltage generator to generate a micro-driving pulse voltage to drive the piezoelectric element to vibrate a meniscus formed on the nozzle, the micro-driving pulse voltage being smaller than the discharge pulse voltage so that the micro-driving pulse voltage does not drive the piezoelectric element to discharge liquid droplets from the nozzles; a voltage applier to apply a voltage waveform including a discharge pulse voltage and a micro-driving pulse voltage to the piezoelectric element; and a nozzle activation ratio processor to calculate a nozzle activation ratio of the nozzles based on drive data for discharging liquid droplets from the nozzle, wherein: the micro-drive voltage generator generates a micro-driving pulse voltage, a peak voltage of which corresponds to the nozzle activation ratio calculated by the nozzle activation ratio processor, and the voltage applier applies the voltage waveform including the micro-driving pulse voltage generated by the micro-drive voltage generator and the discharge pulse voltage generated by the drive voltage generator to the piezoelectric element, and wherein: the micro-drive voltage generator generates a plurality of micro-driving pulse voltage, the peak voltage of which are different based the nozzle activation ratio calculated by the nozzle activation ratio processor, the micro-drive voltage generator generates a first micro-driving pulse voltage and the voltage applier applies the voltage waveform including the first micro-driving pulse voltage to the piezoelectric element when the nozzle activation ratio calculated by the nozzle activation processor exceeds a threshold value; and the micro-drive voltage generator generates a second micro-driving pulse voltage, the peak voltage of which is smaller than that of the first micro-driving pulse voltage and the voltage applier applies the voltage waveform including the second micro-driving pulse voltage to the piezoelectric element when the nozzle activation ratio is below the threshold value.