US 5,644,299 AGranted

Ultrasonic material level measurement

AssigneeBindicator Company

InventorWilliam T. Cruickshank

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Abstract

Apparatus for indicating material level that includes a pair of ultrasonic transducers on opposed sides of a space for receiving the material at the level to be detected. A swept frequency oscillator is coupled to one of the transducers so that the transducer radiates into the material space ultrasonic energy that continuously sweeps back and forth between a low frequency range at which such energy is transmitted to the other transducer by resonance of the entire apparatus and independent of presence of material in the material space, and a higher frequency range at which such energy is transmitted to the other transducer only when material is present in the space between the transducers. Detection circuitry indicates presence of material between the transducers upon receipt of the higher frequency energy, and failure of the apparatus upon failure to receive the lower frequency energy.

Claims14

Dependent claims

Apparatus for indicating level of material comprising:

means for operatively coupling a pair of ultrasonic transducers to a space for receiving the material such that energy transmitted between said transducers traverses said space,
means for applying electrical signals to one of said transducers so that said one of said transducers radiates into said space toward the other of said transducers ultrasonic energy that continuously sweeps back and forth between a high frequency range at which energy is transmitted through said space and any material in said space between said sensors and a low frequency range at which energy is transmitted between said sensors through said operatively coupling means independent of said space and any material in said space between said sensors,
means responsive to energy received at said other transducer at said high frequency range for indicating presence of material in said space between said transducers, and
means responsive to energy received at said other transducer at said low frequency range for indicating operative condition of said apparatus including said transducers independent of presence of material in said space between said transducers.

1 more element

Dependencies are inferred from the claim text.