| 摘要 |
A transmission/reception element transmits an ultrasound wave to an ink liquid contained in an ink tank. At this time, a near sound field of the ultrasound wave is formed within a propagating member when it propagates the ultrasound wave transmitted from the transmission/reception element to the ink liquid. The transmission/reception element receives the ultrasound wave that is transmitted, reflected on the surface of the ink liquid, and comes back. An ink remaining amount calculating unit calculates the remaining amount of the ink liquid based on an elapsed time required from the transmission until the reception.
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