Patent ID: 7981384

Claim:
A liquid aspirator system for aspirating liquid from a liquid container for containing the liquid therein, the liquid aspirator comprising: an open container; an aspirating pipette; a stepping motor for descending the aspirating pipette into the open liquid container; a liquid aspirating pump for supplying pressure for aspirating liquid through the aspirating pipette; a position detecting sensor for detecting the positioning the pipette at an initial position; a drive circuit unit for supplying a motor drive current to the stepping motor; and a controller for controlling the stepping motor and the liquid aspirating pump; the controller controls the stepping motor with N number of drive pulses to output a predetermined drive force to move the pipette from the initial position, where the drive pulse number N has been programmed into the controller in advance, where a distance from a tip of the pipette to a bottom of the open liquid container corresponds to a number of drive pulses N 0 to a second position in contact with the bottom of the open liquid container (N>N 0 ), the movement of the pipette from the initial to the second position being effected and completed solely with supply of the N number of drive pulses to the stepping motor, wherein the controller controls the drive circuit unit to supply the motor drive current from the drive circuit unit to the stepping motor so as to descend the aspirating pipette and to continuously supply the motor drive current to the stepping motor after the aspirating pipette is brought into inelastic contact with the bottom of the open liquid container disposed under the aspirating pipette in the second position such that synchronization of the stepping motor is lost, wherein the controller controls the liquid aspirating pump so that the liquid aspirating pump aspirates the liquid through the aspirating pipette that contacts the bottom of the open liquid container in the second position.