Electron gun with a gamma correct field emission cathode

A gate structure of an electron gun having a field emission cold cathode having a first electrical potential, said gate structure comprising:

• a primary gate electrode having a first opening portion surrounding said top of said cathode, said primary gate electrode having a second electrical potential which is higher than said first electrical potential for causing an electron emission from said top of said cathode;
• and
• a secondary gate electrode having a second opening portion surrounding said primary gate electrode, said secondary gate electrode being spaced apart from said primary gate electrode in a direction perpendicular to a traveling direction along which electrons emitted from said top of said cathode travel, said secondary gate electrode having a third electrical potential which is higher than said first electrical potential and lower than said second electrical potential so as to provide a current-voltage characteristic which suppresses said electron emission in a low current region,
• wherein a second voltage comprising a difference between said first and third electrical potentials varies in proportion to a first voltage comprising a difference between said first and second electrical potentials so that said current-voltage characteristic has an apparent gamma-property.

An electron gun comprising:

• a substrate;
• a field emission cold cathode being provided on said substrate, said field emission cold cathode having a first electrical potential;
• a primary gate electrode being spaced apart from said substrate in a direction parallel to a traveling direction along which electrons emitted from said top of said cathode travel, said primary gate electrode having a first opening portion surrounding said top of said cathode, said primary gate electrode having a second electrical potential which is higher than said first electrical potential for causing an electron emission from said top of said cathode;
• at least a secondary gate electrode having a second opening portion and being spaced apart from said primary gate electrode in a direction parallel to said traveling direction, said secondary gate electrode having a third electrical potential which is higher than said first electrical potential and lower than said second electrical potential so as to provide a current-voltage characteristic which suppresses said electron emission in a low current region,
• wherein a second voltage comprising a difference between said first and third electrical potentials varies in proportion to a first voltage comprising a difference between said first and second electrical potentials so that said current-voltage characteristic has an apparent gamma-property;
• and
• an anode electrode being spaced apart from said primary and secondary gate electrodes in a direction parallel to said traveling direction so that electrons emitted from said cathode travel toward said anode electrode.

An electron gun comprising:

• a substrate;
• a field emission cold cathode being provided on said substrate, said field emission cold cathode having a first electrical potential;
• a primary gate electrode being spaced apart from said substrate in a direction parallel to a traveling direction along which electrons emitted from said top of said cathode travel, said primary gate electrode having a first opening portion surrounding said top of said cathode, said primary gate electrode having a second electrical potential which is higher than said first electrical potential for causing an electron emission from said top of said cathode;
• a secondary gate electrode being spaced apart from said primary gate electrode in a direction perpendicular to said traveling direction, said secondary gate electrode having a second opening portion surrounding said primary gate electrode, said secondary gate electrode having a third electrical potential which is higher than said first electrical potential and lower than said second electrical potential so as to provide a current-voltage characteristic which suppresses said electron emission in a low current region,
• wherein a second voltage comprising a difference between said first and third electrical potentials varies in proportion to a first voltage comprising a difference between said first and second electrical potentials so that said current-voltage characteristic has an apparent gamma-property;
• and
• an anode electrode being spaced apart from said primary and secondary gate electrodes in a direction parallel to said traveling direction so that electrons emitted from said cathode travel toward said anode electrode.