A double cathode under-gate CNT FED with normally-on driving method

In this paper a normally-on driving under-gate FED is proposed. In this structure, the ratio of the cathode width to the thickness of the dielectric layer is reduced significantly comparing with the traditional under-gate FED. In the new driving scheme, the field emission electrons are extracted from the whole cathode surface by the high anode voltage directly. The effect of the under-gate is to prevent the field emission when the negative voltage is applied on the gate electrode. The electric field inside the emission region is calculated by finite element method. The emission property of the CNT film and spot on the anode are also studied by numerical calculation method. A uniform emission from cathode is obtained using this driving scheme, which prolong the life of cathode. However there are still some disadvantages for this driving scheme, such as the modulation voltage of gate is large and the spot size is about one third of the pixel area, which brings unideal display effect and decrease the lifetime of phosphor layer. In order to solve these problems, a double cathode structure is proposed.