Patent ID: 7053633

Claim:
A capacitance detection device that reads asperity information for a subject surface by outputting a detection signal corresponding to the capacitance formed between the subject surface and the capacitance detection device, comprising: a detection unit in which is arranged a plurality of capacitance detection circuits that output the detection signal; and an amplification circuit that amplifies the detection signal, wherein the capacitance detection circuit comprises a reference capacitance having a fixed capacitance value, a sensor electrode for forming a capacitance between the subject surface and the sensor electrode, a signal output element that outputs a detection signal corresponding to a capacitance ratio of the reference capacitance to the capacitance formed between the subject surface and the sensor electrode, a low potential source line that connects to the signal transmission path of the detection signal; and a scan line for selecting the capacitance detection circuit, wherein the scan line charges the reference capacitance, wherein the amplification circuit functions as a signal source for outputting the detection signal to the capacitance detection circuit and is constituted such that the detection signal is transmitted from the amplification circuit to the low potential source line via the signal output element.