Patent ID: 7448717

Claim:
A container comprising: a container body accumulating liquid therein and having a delivering passage for delivering the liquid to an outside of the container body; a sensor receiving portion provided in the container body in the vicinity of an end of the delivering passage; a sensor unit, which is mounted in the sensor receiving portion, for detecting the liquid; buffer chambers which are provided in the container body, situate close to the sensor receiving portion through a sensor receiving wall, communicate with an upstream side and a downstream side of the delivering passage, and are disposed in the delivering passage in series; a sealing member which seals the sensor unit and the sensor receiving wall and has elasticity; and a pressing spring which presses the sensor unit against the sensor receiving wall to apply a pressing force required for sealing the sensor unit and the sensor receiving wall to the sealing member, while deforming the sealing member, wherein the sensor unit comprises: a sensor chip which has a sensor cavity for receiving the liquid to be detected, a lower surface of the sensor cavity being opened to receive the liquid and an upper surface thereof being closed by a diaphragm, and a piezoelectric element being provided on an upper surface of the diaphragm; a sensor base which is made of metal and on which the sensor chip is mounted and fixed; a unit base having an upper surface and a lower surface, the upper surface having a recess in which the sensor base is mounted, and the lower surface of the unit base facing the sensor receiving wall when the sensor unit is mounted in the sensor receiving portion; a pressing cover which is mounted and fixed on the unit base to cover the sensor chip, receives the pressing force of the pressing spring, and delivers the pressing force to the unit base; and a pair of terminal plates which is mounted and fixed on the unit base and electrically connected to a pair of electrodes of the sensor chip, wherein a liquid reserving space communicating with the sensor cavity is formed in the unit base, a channel which connects the liquid reserving space with the buffer chambers is provided in the sensor receiving wall, and a mis-assembly preventing structure which allows assembly when parts are assembled in an adequate direction and prevents the assembly by interference between the parts when the parts are assembled in an inadequate direction are provided to at least a set of parts among sets of the sensor unit and the container body, the sensor base and the unit base, the unit base and the terminal plates, and the unit base and the pressing cover.