Patent ID: 7086281

Claim:
A detector of liquid consumption condition comprising; a first vibrating part that can vibrate relatively to a containing space that can be filled and refilled with a liquid, at least a portion of the first vibrating part being exposed to the containing space through a first opening formed in a wall part defining the containing space, the first opening determining an area of the first vibrating part, a first piezoelectric device that can cause the first vibrating part to vibrate based on a driving signal and that can generate a counter electromotive force signal based on a residual vibration of the first vibrating part depending on a liquid consumption condition, a second vibrating part that can vibrate relatively to the containing space, at least a portion of the second vibrating part being exposed to the containing space through a second opening formed in the wall part defining the containing space, the second opening determining an area of the second vibrating part, a second piezoelectric device that can cause the second vibrating part to vibrate based on a driving signal and that can generate a counter electromotive force signal based on a residual vibration of the second vibrating part depending on the liquid consumption condition, and a liquid consumption condition detecting part that can detect the liquid consumption condition based on the counter electromotive force signal from at least one of the piezoelectric devices, wherein: the containing space can contain only a predetermined volume of the liquid, the first vibrating part and the first piezoelectric device are provided in a vicinity of a liquid surface in the containing space when the containing space contains the predetermined volume of the liquid, and the second vibrating part and the second piezoelectric device are provided in a vicinity of a liquid surface in the containing space when the liquid is exhausted from the containing space.