Surface contact imaging sensor
An imaging system disposed on a TFT array employing a capacitance input sensing stage into a diode peak detecting circuit used as a single pixel on a semiconductor or TFT array that is capable of accessing the generated charge across the capacitor, peak detecting it, amplifying it and then distributing it to an external system via row and column addressing. The resulting imaging system is suitable for fingerprint imaging or as a computer touchpad input device.
1. A capacitance sensor pixel element array comprising:
an array of pixels, a plurality of the pixels arranged in rows and columns and each pixel having:
(a) a capacitance transducer that accumulates charges in response to a contoured conductive outer capacitor surface, which is provided by an object to be imaged, a receiver electrode, and a dielectric layer separating the contoured conductive outer capacitor surface from the receiver electrode, and the dielectric layer directly contacting the receiver electrode, wherein at least one of the capacitance transducers includes:
an amplifier having a TFT input, said input being coupled to a reference voltage and the receiver electrode; and
a bias voltage source providing an input voltage to the input of the amplifier; and
(b) a peak detecting circuit electrically connected to the receiver electrode to track the maximum charge available from the capacitance transducer; and
one or more charge amplifiers to collect and amplify the charges collected by the peak detecting circuit; and
a row/column reader to produce a contour map of the outer capacitor surface.
2. The capacitance sensor pixel element array of claim 1 , wherein the capacitance transducer array includes a polymer or copolymer with dielectric qualities.