Patent ID: 7509868
Filing Date: 2009-03-31
Classification: B41J

Abstract:
1. A liquid detecting device comprising: a liquid detection chamber which includes a liquid inlet, a liquid outlet, a flexible diaphragm that is displaced depending on liquid pressure between the liquid inlet and the liquid outlet, and a detection-portion-mounted member having one surface facing the diaphragm, and a volume of which changes with the liquid pressure; a movable member provided within the liquid detection chamber; a detection portion which is provided on the other surface of the detection-portion-mounted member and which includes a detection space portion that communicates with the liquid detection chamber and is separated from the liquid detection chamber by the detection-portion-mounted member, and a piezoelectric sensor that applies vibration to the detection space portion to detect a remaining vibration waveform according to the vibration; and a biasing member which biases the movable member movabely toward the detection-portion mounted member, wherein the movable member has a pressure receiving plate and two shafts formed to protrude from the pressure receiving plate, and the pressure receiving plate is attached to the diaphragm and faces the one surface of the detection-portion-mounted member, the diaphragm expands until a volume of the liquid detection chamber reaches a predetermined volume when the liquid pressure is a predetermined value, such that the pressure receiving plate is spaced apart from the one surface of the detection-portion-mounted member against a biasing force of the biasing member, the movable member causes the pressure receiving plate to come in contact with the one surface of the detection-portion-mounted member at an initial stage where liquid is introduced into the liquid detection chamber, and the diaphragm to be displaced to a position at which the volume of the liquid detection chamber is smaller than the predetermined volume at liquid detection time at which the liquid pressure becomes smaller than the predetermined value, by the biasing force of the biasing member, the movable member further includes a first passage, which guides the liquid from the liquid inlet to the detection space portion at the initial stage, and a second passage, which guides the liquid from the detection space portion to the liquid outlet at the initial stage, and the liquid detection chamber includes shaft receiving members, each of which is provided for positioning of each of the two shafts in a first direction of two perpendicular-axes directions of a two-dimensional plane parallel to the one surface of the detection-portion-mounted member, and facing members, each of which is positioned facing a front end surface of each of the two shafts in a second direction of the two perpendicular axes.