| 摘要 |
PURPOSE:To prevent in advance the occurrence of an improper printing by providing a detecting electrode at the piezoelectric vibrator of an ink jet head and continuously detecting the variation in the exciting characteristics during the ink injection, thereby effectiving detecting the deterioration of the vibtator. CONSTITUTION:When an ultrasonic exciting voltage is applied to an exciting electrode 7 by an exciting circuit 9, a piezoelectric vibrator 5 produces a bending vibration and applies a vibration to an ink in a liquid chamber 2 through a vibrating plate 4. At this time, as the vibrator 5 vibrates, an AC voltage is produced between another electrode 8 electrically insulated from the electrode 7 and an electrode 6. After the detected voltage is compensated for the temperature by a detection signal amplifier 10 and is amplified, the voltage is rectified by a rectifier 11, is smoothed by an integrating circuit 12, and is compared with a reference voltage by a comparator 14. When the voltage of the detection signal becomes lower than a reference voltage, an abnormal indication is performed, and a signal is fed to a controller 19, and a drive signal to a charging electrode 18 is interrupted. |
