Capacitive liquid sensor

A capacitive level gauge assembly for placement in a container to determine the amount or level of a substance therein, said assembly comprising;

• sensing means (18) having [a] first and second [end] ends (22) for measuring the level of substance between said first and second [end] ends ;
• said sensing means including measurement capacitance means (24) extending between said first and second ends comprising at least two parallel conductive members to establish an electrical capacitance therebetween representative of level, and reference capacitance means (30) connected at said second end (22) comprising at least two parallel conductive members to establish an electrical capacitance therebetween representative of dielectric constant;
• measuring means (34) responsive to said level capacitance and reference capacitance for producing a pulsing level signal representing both level and dielectric constant;
• said measuring means (34) including reference timing means (48) connected to said reference capacitance means (30) for producing a pulsing reference signal having a timing component indicative of said reference capacitance and independent of said level capacitance, and level timing means (50) connected to said measurement capacitance means (24) for receiving said reference signal and producing a level signal having a timing component indicative of said level capacitance and the timing component indicative of said reference level capacitance.

A capacitive sensor assembly for placement in a container to determine the level of substance therein, said assembly comprising;

• sensing means (18) separate from the container for measuring the level of substance;
• said sensing means including measurement capacitance means (24) comprising at least two parallel conductive members to establish an electrical capacitance representative of level therebetween, and reference capacitance means (30) comprising at least two parallel conductive members to establish an electrical capacitance representative of dielectric constant;
• measuring means (34) responsive to said reference capacitance means (30) for producing a reference signal representing dielectric constant and responsive to said level capacitance for producing a pulsing level signal representing level of a substance, said measuring means (34) including reference oscillator timing means (48) connected to said reference capacitance means (30) for producing a pulsing reference signal having a first component indicative of said reference capacitance, and a level oscillator timing means (50) independent and separate from said reference timing means (30) and connected to said measurement capacitance means (24) for producing said level signal having a timing component
• indicative of said level capacitance.

A capacitive level gauge assembly for placement in a container to determine the amount or level of a substance therein, said assembly comprising;

• sensing means (18) separate from the container for measuring the level of substance;
• said sensing means including measurement capacitance means (24) comprising at least two parallel conductive members to establish an electrical capacitance therebetween representative of level, and reference capacitance means (30) comprising at least two parallel conductive members to establish an electrical capacitance therebetween representative of dielectric constant;
• measuring means (34) responsive to said level capacitance and reference capacitance for producing a pulsing level signal representing both level and dielectric constant;
• said measuring means (34) including reference oscillator timing means (48) connected to said reference capacitance means (30) for producing a pulsing reference signal having a timing component indicative of said reference capacitance and independent of said level capacitance and level oscillator timing means (50) connected to said measurement capacitance means (24) for receiving said reference signal and producing a pulsing level signal having a timing component indicative of said level capacitance and the timing component indicative of said reference level capacitance.