This invention provides an analyzer that has a liquid dispense pipette dispensing liquids with higher accuracy and precision at higher speeds. The analyzer includes a drive mechanism having a stepping motor as a power source. The drive mechanism transmits power from a rotation output shaft of the stepping motor to a moving unit for executing a target motion via at least one power transmission unit. The amount of idling of the moving unit stemming from the stepping motor getting driven in reverse is calculated from the amount of movement of the moving unit, from the amount of pulses fed to the stepping motor, and from the amount of remaining pulses so as to perform motion control of the drive mechanism accordingly.
1. A dispensing apparatus comprising:
a syringe having a plunger driven by a stepping motor as a power source;
a nozzle for sucking gas and liquid with the driving motion of said syringe;
a flow channel for connecting the nozzle with the syringe;
at least one power transmission unit for transmitting power from a rotation output shaft of the stepping motor to the plunger; and
an electrode for detecting a change of a current or voltage for detecting a boundary surface between a gas layer and a liquid layer in the flow channel when the plunger is driven in case that a gas and liquid are in the flow channel,
wherein the amount of idling of the stepping motor before and after the stepping motor driven in reverse direction is calculated on the basis of a time at the boundary surface between a gas layer and a liquid layer passing through the electrode and the amount of the movement of the plunger.
2. The dispensing apparatus according to claim 1 , wherein a motion control of a drive mechanism is performed on the basis of the calculated the amount of idling.
3. The dispensing apparatus according to claim 1 , wherein a method for controlling the drive mechanism based on the amount of idling at the stepping motor driven in reverse direction involves adding a movement reflecting the idling amount to the driving motion of the syringe after the stepping motor has been driven in reverse.
4. An analyzer comprising the dispensing apparatus according to claim 1 , wherein the electrode includes a function for inducing detection reaction for an analysis.
5. An analyzer comprising the dispensing apparatus according to claim 2 , wherein the electrode includes a function for inducing detection reaction for an analysis.
6. An analyzer comprising the dispensing apparatus according to claim 3 , wherein the electrode includes a function for inducing detection reaction for an analysis.