Patent ID: 8789414

Claim:
A level sensing apparatus sensing a level of a detected material, the apparatus comprising: a circuit board; a reference electrode and a level sensing electrode having different dimensions, which are formed on one surface and the other surface of the circuit board, respectively; a first dielectric layer and a second dielectric layer having different thicknesses, which are formed on the reference electrode and the level sensing electrode; and a judgment unit electrically connected with the reference electrode and the level sensing electrode through the circuit board to judge the level of the detected material by using capacitances detected from the reference electrode and the level sensing electrode, respectively, wherein the thicknesses of the first dielectric layer and the second dielectric layer are formed so that the capacitance formed in the reference electrode is larger than the capacitance formed in the level sensing electrode when the level sensing apparatus is exposed to air, and the dimension of the reference electrode is larger than the dimension of the level sensing electrode so that the capacitance formed in the reference electrode is larger than the capacitance formed in the level sensing electrode when the level sensing apparatus is exposed to air, wherein the dimensions of the reference electrode and the level sensing electrode and the thicknesses of the first dielectric layer and the second dielectric layer are formed so that the capacitance formed in the level sensing electrode is larger than the capacitance formed in the reference electrode when the detected material approaches the level sensing apparatus, and wherein the first dielectric layer encapsulates the reference electrode and the second dielectric layer encapsulates the level sensing electrode.