| 摘要 |
<p>An empty container detector for use with a drip chamber comprises a photoelectric transducer associated with the fluid container which generates a variable control signal to alternately indicate whether the light path of the photoelectric transducer is being refracted by a fluid. A second photoelectric transducer is associated with the fluid container above the fluid level in the container to establish a reference signal which is modulated by drops falling into the container and which has a component corresponding to the condition wherein the light path is not refracted or attenuated by the presence of a fluid. Electrical means are provided to connect the first photoelectric transducer to the second photoelectric transducer to linearize and normalize the reference signal with the control signal. A comparator is associated with the photoelectric transducers and connected to an alarm which indicates when the control signal is substantially equivalent to the reference signal and thus indicating the lowering of the fluid level below the light path of the first photoelectric transducer. Another comparator is associated with the photoelectric transducers to count modulations in the reference signal as indicative of the drops entering the container.</p> |
