Patent ID: 7331645
Filing Date: 2008-02-19
Classification: B41J

Abstract:
1. A method of detecting a liquid amount, comprising: applying a drive signal to a piezoelectric element provided at a predetermined position in a liquid containing section for containing a liquid; detecting an output signal from the piezoelectric element due to a residual vibration after the application of the drive signal; and detecting whether or not the liquid is present at the predetermined position based on the output signal utilizing a difference in resonance frequency of the residual vibration depending on whether or not the liquid is present at the predetermined position, wherein the drive signal includes a first drive waveform portion for driving the piezoelectric element at a resonance frequency of the residual vibration when the liquid is present at the predetermined position and a second drive waveform portion for driving the piezoelectric element at a resonance frequency of the residual vibration when the liquid is not present at the predetermined position.