Method and apparatus for regulating electron emission in field emitter devices

A cathode apparatus, comprising:

• a gate electrode, with at least one aperture therein, is arranged on a substrate;
• an emitter structure formed on the substrate for injecting current when a voltage supply is connected between the gate electrode and the substrate;
• a filter electrode arranged above or adjacent to said gate electrode, for reflecting electrons having energies below a predetermined level for collection by said first electrode;
• and
• a feedback circuit connected to said first electrode for reducing the voltage applied to said first electrode in response to the electrons collected by said first electrode.

A method of regulating current emitted from a cathode, the method comprising:

• arranging a first electrode, with at least one aperture therein, on a substrate;
• forming an emitter structure on the substrate for injecting current when a voltage supply is connected between the first electrode and the substrate;
• arranging a second electrode above or adjacent to the first electrode;
• collecting electrons failing to pass through the second electrode by said first electrode;
• and
• connecting a feedback circuit to said first electrode for reducing the voltage applied to said first electrode in response to the electrons collected by said first electrode.

A method of reducing beam current in a cathode, comprising:

• forming a gate electrode, with at least one aperture therein, on a substrate;
• forming an emitter structure on the substrate for injecting current;
• forming an energy filter electrode above or adjacent to said gate electrode, for reflecting electrons having energies below a predetermined level;
• collecting electrons reflected by said energy filter electrode at said first electrode;
• and
• connecting a feedback circuit to said first electrode for reducing the voltage applied to said first electrode in response to the electrons collected by said first electrode.

In a cathode device having a gate electrode with a gate aperture therein, an emitter structure, a filter electrode, and a feedback circuit connected to the gate electrode, a method of improving the performance of the field emission cathode comprising:

• detecting emission of electrons having energies less than a predetermined cutoff level;
• adjusting a potential applied to the filter electrode so as to prevent electrons having energies less than the predetermined cutoff level from clearing the potential barrier of the filter electrode;
• deflecting electrons having energies less than the predetermined cutoff level towards the gate electrode;
• collecting the deflected electrons at the gate electrode;
• and
• using the feedback circuit connected to said gate electrode for reducing the electric potential appearing at the gate electrode in response to occurrence of excessive emission below the cutoff level.

An apparatus for improving the performance of a cathode, comprising:

• a filter electrode for detecting the emission of electrons having energies less than a predetermined cutoff level;
• means for adjusting the potentials applied to the filter electrode so as to prevent electrons having energies less than the predetermined cutoff level from passing through an aperture in the filter electrode;
• means for deflecting electrons having energies less than the predetermined cutoff level towards a gate electrode;
• means for collecting the deflected electrons;
• and
• means for reducing the voltage applied to the gate electrode in response to collection of electrons at the gate electrode.

A cathode apparatus capable of regulating current, comprising:

• a first electrode, with at least one aperture therein, arranged on a substrate;
• an emitter structure formed on the substrate for injecting current when a voltage supply is connected between the first electrode and the substrate;
• a plurality of filter electrodes, wherein electrons failing to pass through said filter electrodes are collected by said first electrode;
• and
• a feedback circuit connected to said first electrode for reducing the voltage applied to said first electrode in response to the electrons collected by said first electrode.