Identifying and disabling shorted electrodes in field emission display

A method of disabling current flow between a field emitter tip and an associated grid electrode which are short-circuited in a field emission display, comprising the steps of:

• providing a field emission display having a number of field emitter tips and grid electrodes, each grid electrode being associated with at least one of the field emitter tips, each emitter tip being coupled through an emitter coupling circuit to a negative operating voltage terminal, and each grid electrode being coupled through a grid coupling circuit to a positive operating voltage terminal;
• for each emitter tip, applying a test voltage between first and second points corresponding to that emitter tip, the first point being electrically coupled to that emitter tip and the second point being coupled to a grid electrode associated with that emitter tip, wherein the test voltage is low enough to prevent field emission from any of the emitter tips and grid electrodes;
• and
• during the test voltage applying step, for an emitter tip which is short circuited to an associated grid electrode, conducting a current flow through a path from the first point coupled to that emitter tip, through the emitter tip, through the associated grid electrode, and to the second point coupled to the grid electrode associated with that emitter tip, wherein the current flow is high enough to damage a portion of said path so as to produce an open circuit in said path.

A method of disabling current flow to a short-circuited field emitter tip within a pixel of a field emission display while enabling current flow to other field emitter tips within that pixel, comprising the steps of:

• providing a field emission display having a plurality of pixels, wherein
• each pixel includes a plurality of field emitter tips and a plurality of grid electrodes, each grid electrode being associated with at least one of the field emitter tips within the pixel, and
• each pixel further includes a plurality of removable links, each removable link being bounded by first and second ends;
• for each pixel, connecting the first end of each removable link within the pixel to a distinct subset of the grid electrodes of the pixel;
• for each removable link, applying a test voltage between the second end of that removable link and the field emitter tips associated with the grid electrodes to which that removable link is connected, wherein the test voltage is low enough to avoid producing field emission from any of the emitter tips and grid electrodes;
• and
• during the test voltage applying step, for an emitter tip which is short circuited to an associated grid electrode, conducting a current flow from that emitter tip, through the grid electrode which is short-circuited to that emitter tip, and through the removable link connected to that grid electrode, wherein the current flow is high enough to damage a portion of the removable link so as to produce an open circuit in the removable link.

A method of identifying a field emitter tip electrode which is short-circuited to a grid electrode in a field emission display, comprising the steps of:

• providing said field emission display having a number of field emitter tip electrodes and grid electrodes;
• applying between a number of the emitter tip electrodes and a number of the grid electrodes a test voltage whose magnitude is low enough to avoid producing field emission from any of the electrodes;
• and
• detecting the location within the display of heat radiation from any current flow produced by the test voltage.

A method of identifying which subsets of field emitter tips include any field emitter tip which is short circuited to its corresponding grid electrode in a field emission display, comprising the steps of:

• providing a field emission display having a plurality of field emitter tips and a number of grid electrodes, each grid electrode being associated with at least one of the field emitter tips;
• providing a test voltage between first and second test voltage terminals;
• and
• for each one of a plurality of different subsets of emitter tips, wherein each subset includes one or more emitter tips,
• connecting the first test voltage terminal to the emitter tips in that subset,
• connecting the second test voltage terminal to the grid electrodes associated with the emitter tips in that subset,
• detecting whether the test voltage produces a current flow, and
• identifying that subset of emitter tips as either containing or not containing any emitter tip that is short circuited to its corresponding grid electrode according to whether said current flow is or is not detected for that subset in the detecting step;
• wherein the test voltage is low enough to avoid field emission from any of the emitter tips and grid electrodes.