Grid addressed field emission cathode

A flat cathode ray tube comprising:

• a field emitter cathode;
• an anode;
• and
• a grid interposed between the field emitter cathode and the anode, the grid having a plurality of addressing holes through which electrons emitted by the cathode flow to the anode, the grid controlling electron flow by switching on or off the flow through the addressing holes, wherein:
• the grid further comprises a collecting layer made of conducting material and positioned close to the field emitter cathode;
• the addressing holes pass through the collecting layer;
• and
• the addressing holes in the collecting layer provide an aperture through which electrons emitted by the field emitter cathode must pass before reaching the anode, the collecting layer being sufficiently thick and positioned relative to the field emitter cathode such that most of the electrons which are absorbed by the walls of the addressing holes are absorbed by the collecting layer.

A flat cathode ray tube comprising:

• a field emitter cathode comprising;
• a plurality of sets of micro-emitters;
• and
• a plurality of isolated gate patterns encompassing the sets of micro-emitters so that when the gate patterns are properly biased relative to the micro-emitters electrons are emitted from the micro-emitters;
• an anode;
• and
• a grid interposed between the field emitter cathode and the anode, the grid controlling electron flow between the field emitter cathode and the anode, wherein the grid comprises a conducting row electrodes and the grid is adjacent to the field emitter cathode with the row electrode in electrical contact with the gate patterns.

A flat cathode ray tube comprising:

• a field emitter cathode comprising a plurality of separate field emitter plates, each field emitter plate having a gate;
• an anode;
• and
• a grid interposed between the field emitter cathode and the anode, the grid controlling electron flow between the field emitter cathode and the anode, wherein the grid comprises a conducting layer, and the grid is adjacent to the field emitter cathode with the conducting layer in electrical contact with the gates of the separate field emitter plates such that the gates are electrically connected together.

A flat cathode ray tube comprising:

• a field emitter cathode comprising a plurality of micro-emitters uniformly distributed over an area of the field emitter cathode;
• an anode;
• and
• a grid interposed between the field emitter cathode and the anode, the grid controlling electron flow between the field emitter cathode and the anode, wherein the grid comprises an insulating layer having a plurality of addressing holes which pass through it, the grid being positioned so that the insulating layer is in contact with the field emitter cathode with some of the plurality of micro-emitters beneath the insulating layer and some of the micro-emitters beneath the addressing holes so that, during operation of the flat cathode ray tube, a charge builds up on the insulating layer and stops the micro-emitters beneath the insulating layer from emitting electrons.