US Patent 8115506 Localization of driver failures within liquid crystal displays

Methods and apparatus for determining whether a malfunctioning pixel in a large area substrate, such as a liquid crystal display (LCD) panel, is due to the pixel itself or to the driver circuit for that pixel and for localizing any driver circuit defects are provided. In an effort to localize the driver circuit defects, test pads coupled to the input and/or output of certain driver circuits may be fabricated on the substrate. The voltage or charge of these test pads may be detected using any suitable sensing device, such as an electron beam, an electro-optical sensor, or an electrode in close proximity to the surface of the pixels and/or drivers capacitively coupled to the pixel or driver. For some embodiments, the defective driver circuits may be repaired in the same area as the test area or may be transported via conveyor or robot to a separate repair station.