# US 5,708,321 A · Cathode for electron tube having an electron-emission layer including a lanthanum-magnesium-manganese oxide

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- Number: US 5,708,321 A
- Document ID: US5708321A
- Status: Granted
- Kind: A
- Application number: 08/629,872
- Filed: 1996-04-10
- Granted: 1998-01-13
- Earliest claimed: 1995-10-30
- Assignees: Samsung Display Devices Co., Ltd.
- Inventors: Kyu-nam Joo; Jong-seo Choi; Kwi-seuk Choi; Geun-bae Kim; Sang-won Lee
- Web page: https://patentgrep.com/patent/US5708321A

## CPC

- H01J 1/142: with alkaline-earth metal oxides, or such oxides used in conjunction with reducing agents, as an emissive material
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A cathode for an electron tube includes a base metal containing nickel as a major component and an electron-emissive material layer which is formed on the base metal and comprises an alkaline earth metal oxide including barium oxide as its main component, wherein the electron-emissive material layer further comprises a lanthanum-magnesium-manganese oxide. The cathode of the present invention is fully interchangeable with conventional oxide cathodes and has a longer lifetimes and an improved cut-off drift characteristic.

## Claims

### Claim 1

A cathode for an electron tube comprising a base metal containing nickel as a major component and an electron-emissive material layer provided on said base metal and comprising an alkaline earth metal oxide including barium oxide as its main component, wherein said layer further comprises a lanthanum-magnesium-manganese oxide.

### Claim 2 (depends on 1)

A cathode for an electron tube as claimed in claim 1, wherein said lanthanum-magnesium-manganese oxide is a mixture of La-oxide, Mg-oxide and Mn-oxide.

### Claim 3 (depends on 1)

A cathode for an electron tube as claimed in claim 1, wherein said lanthanum-magnesium-manganese oxide is a mixture of La--Mg composite oxide and Mn-oxide.

### Claim 4 (depends on 3)

A cathode for an electron tube in accordance with claim 3, wherein an amount of said lanthanum-magnesium-manganese oxide is 0.001-20 weight % based on the alkaline earth metal oxide which includes barium oxide as its main component.

### Claim 5 (depends on 1)

A cathode for an electron tube as claimed in claim 1, wherein said lanthanum-magnesium-manganese oxide is La--Mg--Mn composite oxide.