Patent ID: 7078917

Claim:
An electrostatic capacitance detection device for reading surface contours of an object by detecting an electrostatic capacitance, which changes according to a distance with the object, comprising: M individual power supply lines and N individual output lines, arranged in a matrix of M rows×N columns, and electrostatic capacitance detection elements provided on crossing points of the individual power supply lines and the individual output lines, each of the electrostatic capacitance detection elements being formed of a signal detection element and a signal amplification element, the signal detection element being formed of a capacitance detecting electrode, a capacitance detecting dielectric layer and a reference capacitor, the reference capacitor being formed of a reference capacitor first electrode, a reference capacitor dielectric layer and a reference capacitor second electrode, and the signal amplification element being formed of a MIS type thin film semiconductor device for signal amplification, including a gate electrode, a gate insulating layer and a semiconductor layer, using an area of the reference capacitor electrode of S R (μm 2 ), a gate electrode area of the MIS type thin film semiconductor device for signal amplification of S T (μm 2 ), a thickness of the reference capacitor dielectric layer of t R (μm), a dielectric constant of the reference capacitor dielectric layer of ∈ R , a thickness of the gate insulating layer of t ox (μm), and a dielectric constant of the gate insulating layer of ∈ ox , a capacitance C R (reference capacitor capacitance) of the reference capacitor and a transistor capacitance C T of the MIS type thin film semiconductor device for signal amplification are defined as C R =∈ 0 ·∈ R ·S R /t R , C T =∈ 0 ·∈ ox ·S T /t ox where ∈ 0 is permittivity in vacuum, respectively; and using an area of the capacitance detecting electrode of S D (μm 2 ), a thickness of the capacitance detecting dielectric layer of t D (μm), and a dielectric constant of the capacitance detecting dielectric layer of ∈ D , an element capacitance C D of the signal detection element is defined as C D =∈ 0 ·∈ D ·S D /t D where ∈ 0 is permittivity in vacuum, and the element capacitance C D being sufficiently larger than C R +C T , a summation of the capacitance C R of the reference capacitor and the transistor capacitance C T .