Apparatus for ejecting liquid drops and a method of detecting abnormal ejection of a head for ejecting liquid drops

摘要

An apparatus is provided for ejecting liquid drops while eliminating a special sensor (a photosensor) and improve detection accuracy for abnormal ink drop ejection. When the detecting an abnormal ink drop ejection, a drive circuit outputs an actuator-driving voltage in addition to an original drive voltage with a contact of a changeover switch located in a first position. The original drive voltage causes the electrostatic actuator to be driven. Thus, the vibrating plate is vibrated, whereby ink drops are ejected. Thereafter, the electrostatic actuator is charged with a charge according to the actuator-driving voltage. The charging voltage corresponds to the residual vibration of the vibrating plate. Then, the contact of the changeover switch is switched to a residual vibration-detecting circuit. Thus, the residual vibration-detecting circuit is supplied with the charging voltage to thereby output a residual vibration waveform.