Patent ID: 6702196
Filing Date: 2004-03-09
Classification: B41J

Abstract:
A circuit for driving a liquid drop spraying apparatus including a plurality of units for spraying a small amount of liquid drops, each unit comprising a liquid spraying nozzle, a pressure chamber for pressurizing liquid to be sprayed from the nozzle, an introduction hole for supplying liquid to the pressure chamber, and a piezoelectric/electrostrictive element for operating the pressure chamber, wherein the introduction hole of each unit communicates with a common liquid supply path, the ratio of a diameter of the introduction hole to a diameter of the nozzle is in a range of 0.6 to 1.6, and the ratio of a diameter of the nozzle to the thickness of the nozzle is in a range of 0.2 to 4, said circuit comprising:at least one charging circuit for providing an applied voltage signal to the piezoelectric/electrostrictive element to deform a wall of the pressure chamber and eject from the nozzle the liquid supplied to the pressure chamber by a pressure produced in the pressure chamber, and for holding a final charge voltage for a predetermined time; and at least one discharging circuit comprising at least one inductor and at least one resistor connected in series with said piezoelectric/electrostrictive element, said discharging circuit sequentially performing first and second discharging steps with at least two discharge time constants, wherein the first discharge time constant is greater than the second discharge time constant, said discharging circuit starting the second discharging step at a voltage that is 35% to 70% of a voltage difference between a starting charge voltage and a final charge voltage when the starting charge voltage is defined as a reference.