Patent ID: 7497541
Filing Date: 2009-03-03
Classification: B41J

Abstract:
1. A droplet discharging apparatus comprising: means for discharging a discharge liquid in the form of droplets through an aperture by mechanically deforming a piezoelectric element by a normal drive signal; a drive integrated circuit disposed adjacent to and in thermal contact with the piezoelectric element; a control unit that generates the normal drive signal and a cooling drive signal and supplies one of the normal drive signal and the cooling drive signal to the drive integrated circuit, wherein the normal drive signal includes a waveform having a different frequency, a steeper rising slope, a steeper falling slope, and a shorter holding time than the cooling drive signal; a substrate attached to and in thermal contact with the piezoelectric element and the drive integrated circuit; a diaphragm disposed adjacent to and in thermal contact with the piezoelectric element; and a temperature sensor associated with the drive integrated circuit for sensing a temperature of the drive integrated circuit; wherein the sensed temperature of the drive integrated circuit reflects an operating heat of the piezoelectric element due to the piezoelectric element being thermally coupled to the drive integrated circuit via the substrate; wherein the sensed temperature of the drive integrated circuit reflects the temperature of the discharge liquid due to the thermal connection of the discharge liquid, the diaphragm, the piezoelectric element, the substrate, and the drive integrated circuit; wherein the control unit selects between the normal drive signal and the cooling drive signal based on the temperature of the discharge liquid; wherein the droplets are discharged from the aperture based on the selected normal drive signal or cooling drive signal; and wherein a flushing process is implemented between cycles of normal discharge to set the temperature of the discharge liquid to a predetermined temperature, the flushing process including selecting the cooling drive signal following periods of normal discharge to set the temperature of the discharge liquid to a predetermined temperature prior to initiating a subsequent normal discharge.