Patent ID: 7466161

Claim:
An apparatus operative to test an array of pixels formed on a panel, the apparatus comprising: a first linear array of N sensors each sensor comprising: a sensing electrode adapted to be capacitively coupled to a pixel electrode disposed on the panel; and an associated feedback network configured to maintain the voltage of the sensing electrode at a substantially constant voltage when the sensing electrode is positioned in proximity of the pixel electrode to be capacitively coupled thereto, said first linear array of sensors adapted to be scanned over the panel at a continuous rate, wherein said feedback network comprises an operational amplifier comprising a first input terminal coupled to the sensing electrode and a second input terminal coupled to receive a first voltage supply, wherein an output signal of the operational amplifier is used to generate a feedback signal adapted to drive the first input terminal of the operational amplifier; and a second linear array of N sensors spaced at a distance D 1 away from said first linear array of N sensors, said second linear array of N sensors configured to be scanned over a row of the panel pixels at a known time period after the first linear array of sensors are scanned over the row of the panel pixels, wherein said second linear array of sensors are adapted to capacitively measure voltages present on the panel pixels.