The present invention relates, in general, to electron emission display devices, and more particularly, to a novel extraction grid for an electron emission source.
Field emission devices (FEDs) are well known in the art and are commonly employed for a broad range of applications including image display devices. An example of a FED is given in U.S. Pat. No. 5,142,184 issued to Robert C. Kane on Aug. 25, 1992. FEDs typically employ at least two electrodes, such as a cathode conductor and a gate or extraction grid. Generally, the extraction grid and the cathode conductor are formed at right angles to facilitate utilizing row and column addressing to stimulate electron emission from emission tips or emitters. The cathode conductor and the extraction grid typically are electrically isolated by a dielectric layer. During the FED formation, pinholes can form in the dielectric layer and result in electrical shorts between the extraction grid and the cathode conductor. Because of the electrical short, the cathode conductor and the extraction grid are forced to the same potential thereby preventing a column of emitters and the row from being energized. The shorted column of emitters can not generate an image, thus, a display device formed with such electrical shorts usually has either a dark or a continually bright line where the shorted rows and columns are positioned.
Accordingly, it is desirable to have an electron source that remains functional if the extraction grid is shorted to the cathode conductor.