Patent ID: 9513245
Filing Date: 2016-12-06
CPC Classification: G01N,H01L

Claim Text:
1. A capacitive humidity sensor comprising: a substrate; a detection capacitive device formed in the substrate and having a capacitance changing at a first ratio with respect to a change in ambient humidity; and a reference capacitive device formed in the substrate and having a capacitance changing at a second ratio smaller than the first ratio with respect to the change in ambient humidity, wherein the detection capacitive device includes a pair of detection electrodes and a detection humidity-sensitive film, the detection electrodes face each other on a predetermined mounting surface of the substrate and are spaced from each other by a first gap, the detection humidity-sensitive film covers the detection electrodes and has a relative permittivity changing with absorption of water, the reference capacitive device includes a pair of reference electrodes and a reference humidity-sensitive film, the reference electrodes face each other on the mounting surface of the substrate and are spaced from each other by a second gap, the reference humidity-sensitive film covers the reference electrodes and has a relative permittivity changing with absorption of water, the detection humidity-sensitive film and the reference humidity-sensitive film are made of the same material and have the same thickness, the detection electrodes and the reference electrodes are made of the same material and have the same width and thickness, the first ratio is a ratio of the capacitance of the detection capacitive device at a relative humidity of 100% to the capacitance of the detection capacitive device at the relative humidity of 0%, the second ratio is a ratio of the capacitance of the reference capacitive device at the relative humidity of 100% to the capacitance of the reference capacitive device at the relative humidity of 0%, a relationship between the first ratio and the first gap is the same as a relationship between the second ratio and the second gap, a value of the first ratio peaks when the first gap is equal to a first predetermined width, the value of the first ratio increases with an increase in width of the first gap when the first gap is smaller than the first predetermined width, the value of the first ratio decreases with an increase in width of the first gap when the first gap is larger than the first predetermined width, a value of the second ratio peaks when the second gap is equal to a second predetermined width, the value of the second ratio increases with an increase in width of the second gap when the second gap is smaller than the second predetermined width, the value of the second ratio decreases with an increase in width of the second gap when the second gap is larger than the second predetermined width, the first predetermined width is equal to the second predetermined width, and the second gap is smaller than the first gap and the second predetermined width.