Patent ID: 6714666
Filing Date: 2004-03-30
Classification: G06K

Abstract:
A surface shape recognition apparatus comprising:a plurality of sensor electrodes formed on an interlevel insulator on a substrate and insulated from each other; a passivation film formed on said interlevel insulator to cover an upper surface and side surface of each of said sensor electrodes, said passivation film being formed from a dielectric material; a capacitance detection circuit for, when a target recognition object comes into contact with a surface of said passivation film, detecting an electrostatic capacitance formed between said sensor electrode and a surface of said target recognition object opposing said sensor electrode; and static electricity avoiding means for passing static electricity on the surface of said passivation film, said static electricity avoiding means including a ground electrode formed into a matrix shape, said static electricity avoiding means comprises a ground electrode formed on said interlevel insulator to be insulated from said sensor electrodes and partially forming one surface together with said passivation film, and a static electricity protection element inserted between said capacitance detection circuit and said sensor electrode, wherein said plurality of sensor electrodes are arranged at centers of cells of said ground electrode formed into the matrix shape and each of said sensor electrodes is formed into a size with which a plurality of sensor electrodes are covered with a contact surface of said target recognition object in contact with the surface of said passivation film, said capacitance detection circuit is formed under said interlevel insulator on said substrate and said capacitance detection circuit comprises a signal generation circuit connected to said sensor electrode to generate a signal corresponding to the electrostatic capacitance and an output circuit for receiving a signal generated at a connection portion between said sensor electrode and said signal generation circuit, converting the signal into a desired signal, and outputting the desired signal, and said static electricity avoiding means is provided as a static electrictity protection element on an input side of all circuits connected to said sensor electrode, said ground electrode is connected to a reference electrode to which a predetermined potential is applied outside a region where said sensor electrodes are laid out and said ground electrode partially forms one surface together with said passivation film.