Method to determine pixel condition on flat panel displays using an

Abstract

Testing of flat panel displays (FPDS) during manufacture is effected using an E-beam testing system operating in conjunction with unique signal processing and analysis. The E-beam testing system stimulates secondary electron emission by the thin film transistors (TFTs) of the FPD which is proportionate to the voltage of the TFTs. The TFTs, which are simultaneously activated by predetermined activation signal waveforms, exhibit voltage response patterns which are indicative of their operational condition. The response signal patterns are correlated with one or more test signals each associated with a matched filter whose output is dependent on the degree of similarity between the voltage signal and a test signal. The E-beam system uses a CRT gun to direct a beam of electrons at the substrate, which is at least partially disposed in a vacuum chamber. The vacuum chamber is evacuated and provided with an electron detector to sense secondary electron emission due to impingement of the electron stream on the substrate. In an alternative embodiment, a plurality of CRT guns are used in conjunction with a common vacuum chamber. The plural CRTs may share a common electron detector, or may each be provided with an associated electrostatically isolated detector. The system is preferably used to detect flat panel displays (FPDs) during manufacture.