| 摘要 |
An ultrasonic nebuliser (1) includes a nebulisation chamber (4) for holding a liquid (5) to be nebulised, the liquid (5) being delimited by an upper boundary (6) within the chamber (4); and a nebulisation source (2,10) acoustically couplable to the liquid (5) within the chamber (4) to provide therein an ultrasonic output at an amplitude to cause nebulisation characterised in that the nebulisation source (2,10) is controllable to vary the amplitude of the output to provide a measurement period during which no nebulisation occurs and in that there is provided a sonar device (2,11) adapted to measure during the measurement period a time interval between an emission of an acoustic pulse (13) towards the boundary (6) and a detection of a component of the emitted acoustic pulse reflected from the boundary (6) and to provide an output signal dependent on the measured time interval for use in determining location information on the boundary (6) within the chamber (4). <IMAGE> |
