Display device

A display device for displaying images when viewed in a viewing direction, comprising:

• a first and a second face plate;
• a set of side walls or a set of spacer means, which together with the face plates, define a vacuum chamber therein;
• an anode placed on or near the first face plate in the chamber;
• cathodoluminescent means in the chamber on or near the anode, for generating light in response to bombardment of electrons;
• a multitude of electron emitting cathode elements, each containing at least one control gate, at least one base electrode and at least one field emitter, on or near the second face plate;
• means for applying voltage to the cathode elements to cause the elements to generate electrons forming an electron cloud;
• control electrodes in two or more individual layers between the anode and the cathode to control and accelerate the free electrons generated by the cathode towards the anode and the cathodoluminescent means to cause the cathodoluminescent means to emit light for displaying images;
• and
• means for applying electrical potentials to the control electrodes such that electrons from the electron cloud are directed to selected locations of the cathodoluminescent means in selected quantities for displaying images at said desired locations of the desired brightness, said device further comprising spacer means having a surface and a multitude of uniformity enhancement electrodes, made of transparent or metal conductors on the surface of one of the face plates or the surface of the spacer means, and means for positively energizing said uniformity enhancement electrodes to create electric fields to spread out the electrons generated by the cathodes.

A display device for displaying images when viewed in a viewing direction, comprising:

• a first and a second face plate;
• a set of side walls or a set of spacer means, which together with the face plates, define a vacuum chamber therein;
• an anode placed on or near the first face plate in the chamber;
• cathodoluminescent means in the chamber on or near the anode, for generating light in response to bombardment of electrons;
• a multitude of electron emitting cathode elements, each containing at least one control gate, at least one base electrode and at least one field emitter, on or near the second face plate;
• means for applying voltage to the cathode elements to cause the elements to generate electrons forming an electron cloud;
• control electrodes in two or more individual layers between the anode and the cathode to control and accelerate the free electrons generated by the cathode towards the anode and the cathodoluminescent means to cause the cathodoluminescent means to emit light for displaying images;
• and
• means for applying electrical potentials to the control electrodes such that electrons from the electron cloud are directed to selected locations of the cathodoluminescent means in selected quantities for displaying images at said desired locations of the desired brightness, wherein at least one of the cathode elements further comprises an uniformity enhancement electrode and means for positively energizing said uniformity enhancement electrode to create an electric field so as to diffuse the electrons emitted by the emitter tip.

A display device for displaying images when viewed in a viewing direction, comprising:

• a first and a second face plate;
• a set of side walls or a set of spacer means, which together with the face plates, define a vacuum chamber therein;
• an anode placed on or near the first face plate in the chamber;
• cathodoluminescent means in the chamber on or near the anode, for generating light in response to bombardment of electrons;
• an array of electron emitting cathode elements, each containing at least one control gate, at least one base electrode and at least one field emitter, on or near the second face plate;
• means for applying voltage to the cathode elements to cause the elements to generate electrons forming an electron cloud;
• control electrodes between the anode and the cathode elements to control and accelerate the free electrons generated by the cathode towards the anode and the cathodoluminescent means to cause the cathodoluminescent means to emit light for displaying images in more than one scanned area, each scanned area overlapping and corresponding to one of the control electrodes when viewed in a viewing direction;
• and
• means for applying electrical potentials to the control electrodes such that electrons from each cathode element are directed to more than one scanned area of the cathodoluminescent means corresponding to more than one control electrode in selected quantities for displaying images at said scanned areas of the desired brightness.