Patent ID: 7127089

Claim:
An electrostatic capacitance detection device that reads surface contours of a target object by detecting electrostatic capacitance which changes according to a distance from the target object, the device comprising: an M number of individual power-supply lines, and an N number of individual output lines arranged in a matrix of M rows and N columns; an electrostatic capacitance detecting element formed at the intersection between the individual power-supply lines and the individual output lines, the electrostatic capacitance detecting element including a signal detection element and a signal amplifying element, the signal detection element including a capacitance detecting electrode and a capacitance detecting dielectric layer, and the signal amplifying element including an MIS thin-film semiconductor device for signal amplification, including a gate electrode, a gate insulator, and a semiconductor layer; a source region of the MIS thin-film semiconductor device for signal amplification being connected to the individual output line; a drain region of the MIS thin-film semiconductor device for signal amplification being connected to the individual power-supply line; the gate electrode of the MIS thin-film semiconductor device for signal amplification being connected to the capacitance detecting electrode; an element capacitance C D being sufficiently larger than a transistor capacitance C T , the transistor capacitance C T of the MIS thin-film semiconductor device for signal amplification being defined by the equation: C T =∈ 0 ·∈ ox ·L·W/t ox where L (μm) is the gate electrode length, W (μm) is the sate electrode width of the MIS thin-film semiconductor device for signal amplification, t ox (μm) is the thickness of the gate insulator, ∈ ox is the dielectric constant of the gate insulator, and ∈ 0 is the permittivity in vacuum; and the element capacitance C D of the signal detection element is defined by the equation: C D =∈ 0 ·∈ D ·S/t D where S (μm 2 ) is the area of a capacitance detecting electrode, t D (μm) is the thickness of the capacitance detecting dielectric layer, ∈ D is the dielectric constant of the capacitance detecting dielectric layer, and ∈ 0 is the pennittivity in vacuum.