Patent ID: 7772755

Claim:
A thermionic emission device comprising: an insulating substrate; one or more grids located on the insulating substrate, wherein each grid comprises: a first, second, third and fourth electrode down-lead located on the periphery of the gird, wherein the first and the second electrode down-leads are parallel to each other, the third and fourth electrode down-leads are parallel to each other, and the first and the second electrode down-leads are insulated from the third and fourth electrode down-leads respectively; and a thermionic electron emission unit, the thermionic electron emission unit comprises a first electrode, a second electrode, and a thermionic electron emitter, the first electrode and the second electrode separately located and electrically connected to the first electrode down-lead and the third electrode down-lead respectively; wherein the insulating substrate comprises one or more recesses located on a surface thereof corresponding to the one or more grids respectively.