Patent ID: 7812513

Claim:
A planar light source, comprising: an anode comprising a first electrically conductive layer and a fluorescent layer formed on the first electrically conductive layer; and a field emission cathode spaced apart from the anode, the field emission cathode comprising a second electrically conductive layer, a getter layer and an electron-emitting layer, the getter layer being disposed on the second electrically conductive layer, the electron-emitting layer being electrically connected with the second electrically conductive layer and facing toward the fluorescent layer, the electron-emitting layer comprising an electron-emitting material capable of emitting electrons to strike the fluorescent layer, and the getter layer collecting outgassed materials during the operation of the planar light source; wherein the electron-emitting layer and the getter layer are two separate layers, the electron-emitting layer is located on the getter layer, the getter layer is disposed directly between the electrically conductive layer and the electron-emitting layer.