# US 5,708,327 A · Flat panel display with magnetic field emitter

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- Number: US 5,708,327 A
- Document ID: US5708327A
- Status: Granted
- Kind: A
- Application number: 08/665,566
- Filed: 1996-06-18
- Granted: 1998-01-13
- Earliest claimed: 1996-06-18
- Assignees: National Semiconductor Corporation
- Inventors: John O. O'Boyle
- Web page: https://patentgrep.com/patent/US5708327A

## CPC

- H01J 1/3042: {microengineered, e.g. Spindt-type}
- H01J 2201/30446: characterised by the emitter material
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A flat panel display device (50) includes magnetic field emitter elements (52). The emitter elements (52) include a dopant ferromagnetic material (56) used to produce a permanent magnet in the emitter elements (52). The permanent magnet in the emitter elements (52) generates a magnetic field (B) used to focus the electrons emitted from the tips of the emitter elements (52). The flat panel display device (50) further includes a voltage source (70) for producing an electric field (E) between a cathode electrode (54) having a gate electrode (58), and an anode electrode (60) having phosphor regions (62) disposed between black matrix regions (61). The magnetic field (B) provides a restoring magnetic force to collimate the electrons toward the phosphor regions (62) to produce a high brightness display.

## Claims

### Claim 1

A flat-panel display device, comprising:
a cathode electrode;
a field emitter arranged on the cathode electrode, the field emitter being formed from a material or materials which includes a ferromagnetic material, the ferromagnetic material forming a permanent magnet which produces a magnetic field in a region external to the field emitter;
a substrate;
an anode electrode disposed on said substrate having a phosphor region thereon spaced apart from the cathode electrode; and
a voltage source for producing an electric field in a region between the cathode electrode and the anode electrode.

### Claim 2 (depends on 1)

The flat-panel display device of claim 1, further comprising:
a gate electrode placed around the field emitter and between the cathode electrode and anode electrode for extracting electrons from the field emitter.

### Claim 3 (depends on 1)

The flat-panel display device of claim 1, wherein the ferromagnetic material is cobalt.

### Claim 4 (depends on 1)

The flat-panel display device of claim 1, wherein the ferromagnetic material is evenly distributed within the field emitter.

### Claim 5 (depends on 1)

The flat-panel display device of claim 1, wherein the field emitter is in the shape of a cone.

### Claim 6

A flat-panel display device, comprising:
a cathode electrode;
an array of field emitters arranged on the cathode electrode, wherein each field emitter includes a ferromagnetic material; a substrate;
an anode disposed on said substrate electrode spaced apart from the cathode electrode;
a detector which detects the impact of electrons emitted from the array of field emitters and responds by generating photons of light; and
a voltage source for producing an electric field in a region between the cathode electrode and the anode electrode.

### Claim 7 (depends on 6)

The flat-panel display device of claim 6, wherein the field emitters in the array of field emitters further comprise:
a gate electrode placed-around the emitter and between the cathode electrode and the anode electrode for extracting electrons from the emitter.

### Claim 8 (depends on 6)

The flat-panel display device of claim 6, wherein the ferromagnetic material is cobalt.

### Claim 9

A method of operating a flat-panel display device, comprising:
forming an array of field emitter elements, wherein the emitter elements include a permanent magnet formed from a ferromagnetic material;
arranging the array of field emitter elements between a cathode electrode and an anode electrode disposed on a substrate, wherein the array of emitter elements is electrically connected to the cathode electrode; and
applying a potential between the cathode electrode and the anode electrode having a phosphor region thereon, thereby forming an electric field in a region between the cathode electrode and the anode electrode.

### Claim 10 (depends on 9)

The method of claim 9, wherein the field emitter elements are in the shape of a cone.

### Claim 11 (depends on 9)

The method of claim 9, wherein the ferromagnetic material is cobalt.

### Claim 12 (depends on 9)

The method of claim 9, wherein the ferromagnetic material is evenly distributed within the field emitter elements.

### Claim 13 (depends on 9)

The method of claim 9, further comprising the step of:
arranging a gate electrode around each of the field emitter elements and in between the cathode electrode and the anode electrode for extracting electrons from the emitter.