Discharge lamp with interference shielding

• US 4,568,859 A
• Filed: 12/20/1983
• Issued: 02/04/1986
• Est. Priority Date: 12/29/1982
• Status: Expired due to Term

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Postma, Pieter, Denneman, Jan W., Houkes, Henk
• Primary Examiner(s): Lindsay, Robert
• Application Number:
  US06/563,498
• Time in Patent Office: 777 Days
• Field of Search: 315/248, 315/344, 315/85, 313/492, 313/493
• US Class Current: 315/248
• CPC Class Codes: H01J 61/02 Details
• CPC Class Codes: H01J 61/35 provided with coatings on the walls thereof; Selection of materials for the coatings using coloured coatings H01J61/40; using luminescent coatings H01J61/42
• CPC Class Codes: H01J 65/048 the field being produced by using an excitation coil

Abstract

A discharge lamp having a sealed glass vessel filled with gas and a metal vapor, operated with a supply at a frequency of at least 20 kHz. An interference-suppressing conductive layer is arranged on a wall surface surrounding the discharge, and connected to an electric supply lead-in wire. Preferably, a plurality of insulated metal rings, on the outside of the wall, also surround the discharge.

Claims

1. A discharge lamp comprising:

a glass lamp vessel having a wall, and sealed in a vacuum-tight manner,

a metal vapor and a rare gas contained within said vessel, said vessel and said vapor and gas being arranged and selected such that said lamp is operable with a high-frequency supply voltage to produce an electric discharge within the vessel,

at least one lead-in wire for connection to electric supply means, and

an interference-suppressing transparent conductive layer disposed on a surface of the wall of said vessel, arranged to surround the discharge,

characterized in that said interference-suppressing layer has a sheet resistance of at most approximately 100 ohms, and is connected to one of said lead-in wires.

2. A lamp is claimed in claim 1, characterized in that the interference-suppressing layer consists of tin-doped indium oxide.

3. An electrodeless lamp as claimed in claim 2, characterized in that the glass vessel and filling are selected for operation at a frequency of more than 1 MHz, and that the sheet resistance of the interference-suppressing layer is at most 100 ohms.

4. An electrodeless lamp as claimed in claim 1, characterized in that the glass vessel and filling are selected for operation at a frequency of more than 1 MHz, and that the sheet resistance of the interference-suppressing layer is at most 100 ohms.

5. A discharge lamp comprising:

a glass lamp vessel havng a wall, and sealed in a vacuum-tight manner,

a metal vapor and a rare gas contained within said vessel, said vessel and said vapor and gas being arranged and selected such that said lamp is operable with a high-frequency supply voltage to produce an electric discharge within the vessel,

at least one lead-in wire for connection to electric supply means, and

an interference-suppressing transparent conductive layer disposed on a surface of the wall of said vessel, arranged to surround the discharge,

characterized in that said interference-suppressing layer has a sheet resistance of at most 100 ohms, and is connected to one of said lead-in wires, and

the lamp includes a plurality of metal rings, insulated from each other and from said lead-in wires, arranged on the outside of said lamp vessel wall so as to surround the discharge.

6. A lamp as claimed in claim 5, characterized in that said plurality of rings consists of three copper wires.

7. A lamp as claimed in claim 5, characterized in that said plurality of metal rings consists of at least three and a maximum of five metal rings.