Importance

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Abstract

A method and apparatus are disclosed for monitoring the contents of a container in order to detect when the contents are below a predetermined level. An optical metering signal from a light source driven by a multivibrator is projected at a predetermined level across the space within the container. A light sensor on the opposite side of the space within the container detects incident illumination there. The metering signal is incident there only when the contents of the container are below the predetermined level. Otherwise, the contents either block or refract the metering signal from its normal path, and the metering signal goes undetected. A unity gain amplifier of variable sign coupled to the light sensor and to the multivibrator determines when signal from the light sensor are synchronized with the output of the multivibrator, so as to be deemed to correspond to pulses of the metering signal. Thereupon a status signal is generated by the inventive monitor indicating that the level of the contents of the container is below the predetermined level. The specific embodiment disclosed has particular application to use with a transparent-walled container, such as the drip chamber of a disposable, sterile fluid administration kit.

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First Claim