Patent ID: 7327596

Claim:
An electrostatic capacitance detection device for detecting electrostatic capacitance that changes in accordance with a distance from a target object to read surface contours of the target object, comprising: electrostatic capacitance detection elements arranged in M rows and N columns; a power supply line supplying power to the electrostatic capacitance detection elements; an output line outputting a signal from the electrostatic capacitance detection elements; M row lines selecting the electrostatic capacitance detection elements disposed on a specific row; and N column lines selecting the electrostatic capacitance detection elements disposed on a specific column, wherein: the electrostatic capacitance detection elements each includes: a) a signal detection element storing a charge in accordance with the electrostatic capacitance; b) a row selection element causing the electrostatic capacitance detection element to enter a selected state in response to a signal from the row line; c) a column selection element causing the electrostatic capacitance detection element to enter a selected state in response to a signal from the column line; and d) a signal amplification element amplifying a signal corresponding to the charge stored in the signal detection element, wherein the signal detection element includes a capacitance detection electrode and a reference capacitor; the signal amplification element is a thin-film semiconductor device for signal amplification including a source electrode, a drain electrode and a gate electrode; the row selection element is a thin-film semiconductor device for row selection including a source electrode, a drain electrode and a gate electrode; the column selection element is a thin-film semiconductor device for column selection including a source electrode, a drain electrode and a gate electrode; the reference capacitor includes a reference capacitor first electrode, a reference capacitor dielectric film and a reference capacitor second electrode; the gate electrode of the thin-film semiconductor device for signal amplification, the capacitance detection electrode, and the reference capacitor second electrode are coupled to each other; the gate electrode of the thin-film semiconductor device for row selection is coupled to the row line; the gate electrode of the thin-film semiconductor device for column selection is coupled to the column line; the source electrode and the drain electrode of the thin-film semiconductor device for signal amplification, the source electrode and the drain electrode of the thin-film semiconductor device for row selection, and the source electrode and the drain electrode of the thin-film semiconductor device for column selection are coupled in series between the power supply line and the output line; and on-resistance of the thin-film semiconductor device for row selection and on-resistance of the thin-film semiconductor device for column selection are smaller than on-resistance of the thin-film semiconductor device for signal amplification.