Cold-cathode cathodoluminescent lamp

• US 6,504,311 B1
• Filed: 03/25/1996
• Issued: 01/07/2003
• Est. Priority Date: 03/25/1996
• Status: Expired due to Fees

• Current Assignee: SI Diamond Technology, Inc. (Nano Magic, Inc.)
• Original Assignee: SI Diamond Technology, Inc. (Nano Magic, Inc.)
• Inventors: Bojkov, Christo P., Kykta, Martin A., Kumar, Nalin
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US08/621,531
• Time in Patent Office: 2,479 Days
• Field of Search: 315/169.3, 315/105, 315/160, 315/246, 315/250, 315/260, 315/271, 313/495, 313/496, 313/497, 313/326, 313/329, 313/351, 313/336, 313/309, 313/310
• US Class Current: 315/169.3
• CPC Class Codes: H01J 2893/0031 Tubes with material luminescing under electron bombardment
• CPC Class Codes: H01J 63/06 Lamps with luminescent screen excited by the ray or stream

Abstract

A pulsed lamp is supplied wherein electrons are supplied from a substantially flat cold cathode having low effective field emission work function and are accelerated to excite light emission from a phosphor layer on a transparent anode plate. The emission site density of the cathode and emission current characteristics vs electric field are selected to provide high light output while requiring only small duty cycle pulses from a voltage generator.

Claims

1. A cathodoluminescent lamp, comprising:

an evacuated envelope comprising a light-transparent area;

an anode in proximity to the light-transparent area;

a layer of phosphor in proximity to the anode;

a substantially flat cold cathode, the cathode comprising a substrate and a surface of low effective field emission work function with a resistive layer between the substrate and the surface of low effective field emission work function; and

electrical connections to the anode and cathode.

2. The lamp of claim 1 wherein the surface of low effective field emission work function comprises a carbonaceous coating on the substrate.

3. The lamp of claim 2 wherein the carbonaceous coating is deposited by chemical vapor deposition.

4. The lamp of claim 2 wherein the carbonaceous coating is deposited by laser ablation.

5. The lamp of claim 2 wherein the carbonaceous coating comprises crystalline diamond.

6. The lamp of claim 1 wherein the flat cold cathode is comprised of a plurality of separate areas of low effective field emission work function on a substrate.

7. The lamp of claim 1 wherein the resistance of the resistive layer is in the range from about 1 megohm to about 100 megohms.

8. The lamp of claim 1 wherein the phosphor layer comprises a mixture of phosphor materials.

9. The lamp of claim 1 further comprising a layer of aluminum on the phosphor layer.

10. The lamp of claim 1 wherein the distance from the flat cold cathode to the anode is less than 5 mm.

11. The lamp of claim 1 further comprising a means for supplying a high voltage between said anode and cathode, said means connected to said electrical connections to the anode and cathode, and wherein said means for supplying high voltage supplies high voltage pulses, the pulses having a duty cycle in the range from about 0.1 percent to about 5 percent.

12. A cathodoluminescent lamp assembly, comprising:

an evacuated envelope comprising a light-transparent area;

an anode in proximity to the light-transparent area;

a layer of phosphor in proximity to the anode;

a substantially flat cold cathode, the cathode comprising a substrate and a surface of low effective field emission work function; and

means for supplying a high voltage between the anode and the cathode, wherein the means for supplying high voltage supplies high voltage pulses, the pulses having a duty cycle in the range from about 0.1 percent to about 5 percent.

13. The lamp assembly of claim 12 wherein the high voltage supplied is greater than 6 kilovolts.

14. The lamp assembly of claim 12 wherein the cathode comprises a carbonaceous coating.

15. The lamp assembly of claim 12 wherein the phosphor layer comprises a mixture of phosphor materials.