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Abstract

A support structure is provided that enables the use of high-voltage phosphors in field-emission flat panel displays, to maintain the vacuum gap between the cathode and the anode at a constant distance and to prevent distortion of the transparent view screen and backing plate of the display. A number of independent techniques each contributes to the solution of the problem of secondary electron emission. One technique is to alter the geometry of the triple junction of the support structure, the cathode, and the vacuum gap, thereby reducing the electrostatic field created at the triple junction. Reducing the electrostatic field reduces the initial primary electron bombardment originating at the triple junction. Altering the geometry of the support surface with respect to the field lines present at the triple junction also increases the probability that impinging electrons will impact at or nearly at right angles, and will also tend to be directed by the field lines back into the 'pocket' created by the shaping of the support structure edge, preventing secondary electrons from escaping and traveling along the structure surface to the anode. In accordance with another technique, the support structure is fluted so as to reduce the average coefficient of secondary electron emission, to trap a proportion of secondary electrons, and to limit the number of hops of other secondary electrons. In another technique, a high resistivity conductive layer is formed at the triple junction in order to reduce the field potential at the triple junction. A similar conductive layer may be formed at the opposite junction of the support structure, the anode, and the vacuum gap. A high resistivity conductive material coated on the surface of the insulating spacer can be used to decrease the charge relaxation time of the insulator, thereby maintaining a constant field potential over the surface of the insulator, reducing areas of high field potential which will tend to accelerate secondary electron emissions. In accordance with other techniques, the support structure is made of a non-porous material and may be coated with a coating having low secondary emission characteristics.

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