The patent applications about FED(Field Emission Display) which are attracting keen attention as next-generation flat display have been increasing remarkably(86 in 1995 was increased to 1,115 in 2003). The reasons for this are the following. First of all, FED has a very bright and wide viewing angles like a cathode-ray tube, and at low coat, it is possible to manufacture the FED which is slim, flat and large in size, like LCD.  Consequently, following LDC and PDP, FED will be expected to take a lead in the large panel markets.The major principles of FED are similar to those of CRT, and FED is using the method to realize the image by making a fluorescent material luminescent with electron beam emitted from electron gun. While CRT uses a method to scan hundreds of