Electronic liquid level gauge
First Claim
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1. An apparatus for measuring the level of a liquid contained in a vessel, comprising:
- (a) an electrode having an electrostatic capacity determined by the liquid level;
(b) an oscillator connected to said electrode for generating oscillator pulses at a repetition period directly proportional to the electrostatic capacity of said electrode;
(c) a reference pulse generator for generating a series of reference pulses at a predetermined repetition period;
(d) a counter, responsive to a start signal, for counting reference pulses from said reference pulse generator, said counter being reset to zero in response to a reset signal; and
(e) a control circuit, responsive to an oscillator pulse from said oscillator for generating said reset signal to reset said counter, and for generating said start signal to start said counter, said start signal being generated with a predetermined time delay relative to the occurrence of the oscillator pulse from the oscillator, thereby permitting said counter to accumulate a count for a time interval between successive reset signals, said count being representative of the liquid level.
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Abstract
An electronic liquid level gauge for measuring the level of a liquid contained in a vessel by employing an electrode pair immersed in the liquid. The electrode pair is associated with an oscillator which generates pulses of a repetition period directly proportional to the electrostatic capacity of the electrode pair. A counter is provided which is reset by an oscillator pulse and starts counting reference pulses of a predetermined repetition rate with a predetermined time delay relative to the occurrence of the oscillator pulse.
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17 Claims
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1. An apparatus for measuring the level of a liquid contained in a vessel, comprising:
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(a) an electrode having an electrostatic capacity determined by the liquid level; (b) an oscillator connected to said electrode for generating oscillator pulses at a repetition period directly proportional to the electrostatic capacity of said electrode; (c) a reference pulse generator for generating a series of reference pulses at a predetermined repetition period; (d) a counter, responsive to a start signal, for counting reference pulses from said reference pulse generator, said counter being reset to zero in response to a reset signal; and (e) a control circuit, responsive to an oscillator pulse from said oscillator for generating said reset signal to reset said counter, and for generating said start signal to start said counter, said start signal being generated with a predetermined time delay relative to the occurrence of the oscillator pulse from the oscillator, thereby permitting said counter to accumulate a count for a time interval between successive reset signals, said count being representative of the liquid level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for measuring the level of a liquid contained in a vessel, said liquid having a specific inductive capacity, comprising:
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(a) a first electrode having an electrostatic capacity determined by the liquid level, said first electrode being connected to a first oscillator for generating first oscillator pulses at a repetition period directly proportional to the electrostatic capacity of said first electrode; (b) a second electrode having an electrostatic capacity determined by the specific inductive capacity of said liquid, said first electrode being connected to a second oscillator for generating second oscillator pulses at a repetition period directly proportional to the electrostatic capacity of said second electrode; (c) a counter for counting said second oscillator pulses from said second oscillator; (d) a control circuit for generating a control signal to reset and at the same time start said counter counting second oscillator pulses each time a predetermined number of first oscillator pulses occurs; (e) a first gate circuit for disconnecting said second oscillator from said counter for a predetermined time each time a predetermined number of first oscillator pulses occurs; and (f) a second gate circuit for disconnecting said first oscillator from said control circuit for a predetermined time each time a predetermined number of second oscillator pulses occurs, thereby permitting said counter to accumulate a count equal to the liquid level for a time interval between successive control signals. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification