| 摘要 |
PROBLEM TO BE SOLVED: To shorten the recording time while improving the flying stability of a recording liquid by easily detecting a temperature change of the recording liquid in an actual driving state in which an operation of generating recording liquid droplets is carried out, and correctly grasping a state of a sound source. SOLUTION: An acoustic lens 6 is arranged to a bottom part of an ink storage part 2, and at the same time, a piezoelectric element 5 is set to a lower face of the acoustic lens 6. Ultrasonic waves are generated from the acoustic lens 6 by impressing a high frequency driving voltage to the piezoelectric element 5 from a driving circuit 7, which are converged to an ink level. A current flowing to the piezoelectric element 5 at this time is detected by an impedance detecting circuit 10. An impedance detection signal is supplied to an ultrasonic wave energy judging circuit 20, whereby an ink temperature is detected from a change of the impedance detection signal to a reference voltage. A heater 70 is controlled by a heater driving control circuit 71.
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