Flat display device

Claim 1

A flat display device comprising a vacuum envelope constituted by a back base plate and a flat display panel provided with an inner fluorescent material layer, a thermionic cathode structure disposed on or near the inner side of said back base plate and extending parallel to said display panel, and a plurality of flat electrode structures stacked together with intervening insulators between said thermionic cathode structure and said fluorescent material layer and each having a plurality of thermionic electron beam passage holes, said plurality of flat electrode structures being arranged such as to control and accelerate thermionic electron beams emitted from said thermionic cathode structure so as to cause said thermionic electron beam to impinge upon picture element regions predetermined in a regular arrangement on the surface of said fluorescent material layer, characterized in that: said thermionic cathode structures (12) includes a plurality of coiled heaters (18) each having an effective thermionic electron emitting portion (18b) constituted by a coating of a thermionic electron emitting material, each of said thermionic electron emitting portions being provided each for each of said picture element region (10); that said thermionic electron passage holes (13c, 14c and 16c) in said flat electrode structures (13, 14 and 16) are each provided at a position corresponding to each of said effective thermionic electron emitting portions; that said coiled heaters are supported in their predetermined portions (18a) other than said effective thermionic electron emitting portions by a plurality of support members (19) such as to hold said effective thermionic electron emitting portions in space (20); and that said support members are arranged such as to connect said coiled heaters in parallel to a heating power source.