| 摘要 |
PURPOSE:To pressurize ink, increase the amount of ink to be injected, and discharge quckly bubbles present in the ink by detecting variable components of low periods below the driving frequency of a piezo-electric vibrator in case where bubbles are present in the injection head. CONSTITUTION:In case where bubbles are present in an injection head 1, when ink is pressurized and injected, the driving wave form at both ends of a piezo- electric vibrator 2 shows a lower periodical variation than its driving frequency. When signals at the both ends reach a lower region passage filter 16, signal from a driving signal generator 14 is interrupted, a signal of low frequency, originated from bubbles, is sent to a Schmit trigger circuit 17 and held there for a certain period of time, and then sent out to a controller 18. Thus, the controller 18 makes the working period of the ink pressurizing pump 11 faster than the usual one and also energizes a heater 13 to heat ink, and discharges quickly bubbles present in the injection head 1, together with ink. |
