Patent ID: 7703868

Claim:
A printing material amount determining method implemented by a printer, wherein a printing material container is attached removably to the printer and comprises a detector and a memory, wherein the detector detects an amount of a printing material stored using a piezoelectric element, wherein the memory stores frequency information regarding a frequency of a driving signal for driving the detector, the method comprising: acquiring the frequency information from the memory; acquiring a first frequency and a second frequency based on the acquired frequency information, wherein the first frequency is lower, by a fixed ratio, than a first natural frequency that is the natural frequency of the detector when the amount of printing material stored in the printing material container is less than a specific amount of printing material, wherein the second frequency is lower than the first frequency; providing a first driving signal and a second driving signal to the piezoelectric element with different timings, wherein the first driving signal has the first frequency and the second driving signal has the second frequency; detecting a first response signal and a second response signal, wherein the first response signal is outputted from the detector in accordance with vibration of the piezoelectric element after the provision of the first driving signal stops, and the second response signal is outputted from the detector in accordance with vibration of the piezoelectric element after the provision of the second driving signal stops; measuring a first vibration frequency included in the first response signal and a second vibration frequency included in the second response signal; and determining the amount of the printing material stored in the printing material container based on at least one of the first vibration frequency and the second vibration frequency.