Patent ID: 7311373
Filing Date: 2007-12-25
Classification: B41J

Abstract:
1. A droplet ejection apparatus having a driving circuit and a plurality of droplet ejection heads, each of the droplet ejection heads including a cavity filled with a liquid, a nozzle communicating with the cavity, an actuator driven by the driving circuit, and a diaphragm displaced by the actuator, the droplet ejection head ejecting the liquid within the cavity through the nozzle in the form of droplets by driving the actuator with the driving circuit, the droplet ejection apparatus comprising: a main power supply that supplies a power to the apparatus; a power cutoff detecting unit that detects cutoff of the main power supply; a standby power supply which supplies a power to the apparatus when the power cutoff detecting unit detects the cutoff of the main power supply; a residual vibration detecting unit that detects a residual vibration of the diaphragm displaced by the driving of the actuator; a storage unit that stores at least one of a vibration pattern of the residual vibration of the diaphragm detected by the residual vibration detecting unit and information obtained from the vibration pattern; and an ejection failure detecting unit that detects an ejection failure of the droplet ejection heads and a cause thereof; wherein the droplet ejection apparatus is constructed so that, when the cutoff of the main power supply is detected by the power cutoff detecting unit, the actuator is driven by the driving circuit, the residual vibration detecting unit detects the residual vibration of the diaphragm displaced by the driving of the actuator, and the storage unit stores the at least one of the vibration pattern of the residual vibration of the diaphragm detected by the residual vibration detecting unit and the information obtained from the vibration pattern, and wherein the ejection failure detecting unit includes an oscillation circuit that oscillates in response to an electric capacitance component that varies with the residual vibration of the diaphragm; wherein, when the cutoff of the main power supply is detected by the power cutoff detecting unit, the ejection failure detecting unit detects an ejection failure of the droplet ejection heads and the cause thereof based on the vibration pattern of the residual vibration of the diaphragm, and the storage unit stores the detection result as the information obtained from the vibration pattern; wherein the vibration pattern of the residual vibration of the diaphragm includes a cycle of the residual vibration; and wherein the ejection failure detecting unit judges that: an air bubble has intruded into the cavity in the case where the cycle of the residual vibration of the diaphragm is shorter than a predetermined range of cycle; the liquid in the vicinity of the nozzle has thickened due to drying in the case where the cycle of the residual vibration of the diaphragm is longer than a predetermined threshold; and paper dust is adhering in the vicinity of the outlet of the nozzle in the case where the cycle of the residual vibration of the diaphragm is longer than the predetermined range of cycle and shorter than the predetermined threshold.