Liquid level detector and alarm device for drip infusion sets

A liquid level detector and alarm device for monitoring the infusion solution in the reservoir bottle of a drip infusion set, comprising:

• a housing and mounting means thereon for fastening said housing to the side wall of said reservoir bottle of said drip infusion set;
• an electrical bridge contained within said housing including a first infrared detector means and a second infrared detector means for detecting the liquid level of an infusion solution in said reservoir bottle and peripheral resistors for normally establishing a voltage output from said bridge of zero, said first and second infrared detector means comprising mutually vertically spaced first and second LED-TR infrared light brightness detectors as voltage sources to thereby drive said electrical bridge to change its output value subject to the change of the liquid level of the infusion solution whereby said change will occur when the liquid level drops below one of said first and second vertically spaced LED-TR detectors;
• analogue/digital converter means for converting the output value of said electrical bridge into a digital signal and for generating said signal, said converter being coupled to said bridge;
• single chip microprocessor means coupled to said converter for receiving digital signals from said analogue/digital converter and for comparing said signals with an initial output value obtained from said electrical bridge;
• buzzer means controlled by said single chip microprocessor means for buzzing when the comparison between the digital signal from said analogue/digital converter and the initial output value from said electrical bridge are different;
• and
• press button means coupled to said microprocessor means, for driving said single chip microprocessor means to record the initial output value of said electrical bridge when depressed once, and to stop said buzzer from operating when depressed twice.