Capacitive liquid sensor
First Claim
1. A capacitive sensor assembly for placement in a container to determine the level of substance therein, said assembly comprising;
- sensing means (18) having a first and second end (22) for measuring the level of substance between said first and second end;
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 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 representative of dielectric constant;
measuring means (34) responsive to said level capacitance for producing a reference signal representing dielectric constant and reference capacitance for producing a level signal representing level of the substance said measuring means (34) including reference timing means (48) connected to said reference capacitance means (30) for producing a reference signal having a timing component indicative of said reference capacitance, and level timing means (50) independent from said reference timing means (30) and connected to said measurement capacitance means (24) for producing a level signal having a timing component indicative of said level capacitance.
0 Assignments
0 Petitions
Accused Products
Abstract
A capacitive level gauge for placement in a container (12) determines the level of substance (14) in the container (12). The gauge (10) includes a measurement capacitor (C1) for measuring level and a reference capacitor (C2) for determining dielectric constant of the substance (14). A controller (34) is responsive to the capacitors (C1, C2) for producing a level signal which simultaneously indicated the level and dielectric constant of the material. The level signal includes a frequency which is representative of dielectric constant and a pulse width representative of level. The gauge (10) supports a first pair of parallel conductive members (26, 28) to establish the measurement capacitor (C1) and a second pair of parallel conductive members (28, 32) spaced along the gauge and below the measurement capacitor (C1) to establish the reference capacitor (C2).
40 Citations
12 Claims
-
1. A capacitive sensor assembly for placement in a container to determine the level of substance therein, said assembly comprising;
- sensing means (18) having a first and second end (22) for measuring the level of substance between said first and second end;
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 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 representative of dielectric constant;
measuring means (34) responsive to said level capacitance for producing a reference signal representing dielectric constant and reference capacitance for producing a level signal representing level of the substance said measuring means (34) including reference timing means (48) connected to said reference capacitance means (30) for producing a reference signal having a timing component indicative of said reference capacitance, and level timing means (50) independent from said reference timing means (30) and connected to said measurement capacitance means (24) for producing a level signal having a timing component indicative of said level capacitance. - View Dependent Claims (2, 4, 5, 6, 7)
- sensing means (18) having a first and second end (22) for measuring the level of substance between said first and second end;
-
3. 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 (22) for measuring the level of substance between said first and second end;
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 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 representative of dielectric constant;
measuring means (34) responsive to said level capacitance and reference capacitance for producing a 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 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.
- sensing means (18) having a first and second end (22) for measuring the level of substance between said first and second end;
-
8. 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 (22) for measuring the level of substance between said first and second end;
said sensor 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 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 representative of dielectric constant;
said assembly characterized by control means (34) responsive to said level capacitance and said reference capacitance for producing a level signal having a frequency indicative of one of said level capacitance and said reference capacitance and a pulse width indicative of the other of said level capacitance and said reference capacitance.
- sensing means (18) having a first and second end (22) for measuring the level of substance between said first and second end;
-
9. A capacitive sensor assembly for placement in a container to determine the level of substance therein, said assembly comprising;
- measurement capacitance means (24) comprising at least two parallel conductive members establishing a level capacitance which varies as a function of level, reference capacitance means (30) comprising at least two parallel conductive members establishing a reference capacitance which varies as a function of dielectric constant of the material, and longitudinal support means having a first end (20) and a second end (22), said second end (22) for supporting said reference capacitance means (30) longitudinally extending along said support means immersed in the substance (14) and said measurement capacitance means (24) longitudinally spaced apart from said reference capacitance means (30) and longitudinally extending along said support means from said second end (22).
- View Dependent Claims (10, 11, 12)
Specification