Patent ID: 6307309
Filing Date: 2001-10-23
Classification: H01J

Abstract:
A field emission cold cathode device; having:a field emission cold cathode element which comprises a plurality of emitters formed on a substrate and each in the shape of a sharply pointed projection, and a gate electrode provided with an opening section to let electrons emit from the respective apexes of said group of emitters and set in the vicinity above said group of emitters, wherein a positive voltage with respect to the emitters is applied to said gate electrode and thereby an electron beam is emitted from the group of emitters;a lens electrode making the electron beam which is emitted from said group of emitters converge; anda target on which the electron beam made to converge by said lens electrode irradiates; wherein:the area S of a region occupied by the group of emitters is equal to or more than9.multidot.I.multidot.L.sup.2 /{4.multidot.e.sub.0 (2.multidot.e/m).sup.1/2.multidot.(Vg.sup.1/2 +Vgl.sup.1/2).sup.3 },where, with respect to the emitters, Vg is the gate voltage, Vgl is the voltage of the lens electrode placed directly above the emitters, I is the current in use, L is the distance between the gate electrode and the lens electrode, m is the mass of the electron, e is the electric charge and e.sub.0 is the permittivity of a vacuum.