Field emission display having an invisible spacer and method

A method of rendering a spacer invisible to a viewer of a field emission display comprising:

• providing a cathode assembly having a plurality of electron emitters, wherein the plurality of electron emitters are designed to emit an electron current;
• providing an anode plate disposed to receive the electron current emitted by the plurality of electron emifters;
• providing a spacer comprised of a bulk spacer material and having a surface, the spacer extending between the cathode assembly and the anode plate, wherein the bulk spacer material has a dielectric constant lees than 100;
• and
• operating the field emission display such that the spacer has a first charging period and a discharging period associated therewith, wherein the first charging period is characterized by the accumulation of a positive electrical charge on the surface of the spacer resulting in a resistivity at the surface that is lower than the resistivity of the remaining bulk spacer material during the first charging period, and wherein the discharging period is characterized by the electron current substantially neutralizing the positive electrical charge on the surface of the spacer by decreasing the anode voltage to below a potential at the surface of the spacer and controlling activation of a plurality of electron emitters positioned proximate the spacer during neutralization to avoid excessive electron emission, such that a controlled voltage change on the surface of the spacer is low enough to prevent distortion of the trajectory of the electron current proximate to the spacer to an extent sufficient to render the spacer invisible to the viewer of the field emission display.

A method of controlling a voltage change on a spacer in a field emission display comprising:

• providing a cathoding assembly having a plurality of electron emitters, wherein the plurality of electron emitters are designed to emit an electron current;
• providing an anode plate having a phosphor, wherein the phosphor is disposed to receive the electron current emitted by the plurality of electron emitters;
• providing a spacer composed of a bulk material having a surface, the spacer extending between the cathode assembly and the anode plate, wherein the bulk spacer material has a dielectric constant less than 100;
• and
• operating the field emission display such that the spacer has a first charging period and a discharging period associated therewith, wherein the first charging period is characterized by the accumulation of a positive electrical charge on the surface of the spacer, and wherein the discharging period is characterized by the electron current substantially neutralizing the positive electrical charge on the surface of the spacer by decreasing the anode voltage to below a potential at the surface of the spacer to ensure the electrons are attracted to the spacer surface and activating a plurality of electron emitters positioned proximate the spacer during neutralization to avoid excessive ectron emission, such that a controlled voltage change on the surface of the spacer is low enough to prevent distortion of the trajectory of the electron current proximate to the spacer to an extent sufficient to render the spacer invisible to the viewer of the field emission display.