Patent ID: 7581660

Claim:
A liquid-metering device for aspirating and dispensing liquids, the device comprising: a vessel which is at least partially filled with a gas and has an opening through which a liquid is received into the vessel or is discharged therefrom, the gas, when the liquid is received, being enclosed by vessel walls and the liquid itself; a gas-pressure-changing device for changing the gas pressure in said vessel; a state-variable-detecting device for detecting at least one state variable of the gas in said vessel; and a control device which activates said gas-pressure-changing device as a function of the state variable detected by said state-variable-detecting device, wherein said control device is a regulating device which, at least during a regulating time segment between liquid reception and liquid discharge, activates said gas-pressure-changing device as a function of the detected state variable in such a manner that the actual gas pressure in said vessel is kept essentially at a predetermined desired gas pressure during the regulating time segment, and further, wherein the regulating time segment comprises a time domain in a first half of a period of time lying between a final moment of a liquid-receiving operation and a moment of starting a liquid-discharging operation.