Identifying and disabling shorted electrodes in field emission display

Abstract

Methods and apparatus for identifying and disabling shorted electrode pain (such as field emitter tip electrodes shorted to grid electrodes) in a field emission display by applying a test voltage across the two electrodes in each pair. The magnitude of the test voltage is set below the voltage required to initiate field emission from the emitter tip electrode. Because no field emission occurs at this voltage, the test voltage should produce no current flow through good (non-shorted) emitter tips. However, current will flow through emitter tips which are shorted to their respective grid electrodes. In one embodiment, the current flow vaporizes the bad emitter tips themselves. In another embodiment, the current flow thermally damages a removable link connected in series with either the shorted emitter tip or the shorted grid electrode. Alternatively, rather than disabling the shorted electrodes, the method of the invention can be used to merely identify shorted electrodes by sensing which electrodes conduct current in response to the test voltage. In one embodiment, the test voltage is applied, preferably simultaneously, to all the electrode pairs in the display, causing a current flow through any shorted electrodes which is high enough to produce resistive heating which can be sensed to locate the shorted electrodes. In another embodiment, the test voltage is applied sequentially to small subsets of the electrode pairs while measuring the resulting current flow. The display can be fabricated with multiple power supply busses to facilitate applying the test voltage to selected subsets of electrode pairs.