Ink remaining amount measuring device, ink-jet recorder comprising same, ink remaining amount measuring method, and ink cartridge

摘要

An ink level detecting unit of an ink jet recording apparatus heightens ink detection accuracy and reliability. A piezoelectric element is provided in an ink tank, an excitation pulse generating part applies an excitation pulse to the piezoelectric element, a sensor detects a frequency of a counter electromotive force waveform from the piezoelectric element based on residual vibration by resonance with a medium in the ink tank, and a judgment part judges the existence of ink on the basis of the detected frequency. The sensor has two band pass filters which cause only waveforms in the predetermined frequency bands that have been previously assumed according to ink presence and absence to pass. A frequency measuring part binarizes the waveform, counts time from the predetermined number-th pulse to the predetermined number of pulses, and detects a frequency on the basis of this time.