Patent ID: 7471093

Claim:
A capacitive humidity sensor comprising: a detecting portion including a first sensor element having a first moisture-sensing film, wherein a relative permittivity of the first moisture-sensing film varies in accordance with humidity such that a first capacitance of the first sensor element varies in accordance with the humidity; and a reference portion including a second sensor element having a second moisture-sensing film, wherein the second sensor element is connected to the first sensor element in series, and a relative permittivity of the second moisture-sensing film varies in accordance with the humidity such that a second capacitance of the second sensor element varies in accordance with the humidity, and a capacitor connected to the second sensor element in parallel, wherein a third capacitance of the capacitor is constant relative to a humidity variation, wherein the first sensor element has a first gradient of a first capacitance variation to the humidity variation, which is different from a second gradient of a second capacitance variation to the humidity variation in the second sensor element.