DIELECTRIC BARRIER DISCHARGE LAMP

• US 20100244688A1
• Filed: 07/09/2008
• Published: 09/30/2010
• Est. Priority Date: 11/28/2007
• Status: Active Grant

• Current Assignee: Philips Lighting BV (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Greuel, Georg, Braun, Norbert
• Granted Patent: US 8,106,588 B2
• Time in Patent Office: Days
• US Class Current: 313/631
• CPC Class Codes: H01J 65/046 the field being produced by using capacitive means around the vessel

Abstract

It is provided a dielectric barrier discharge lamp (10) for providing ultraviolet light, comprising an outer tube (12) filled with a discharge gas for providing ultraviolet light, an inner tube (14) arranged at least partially inside the outer tube (12), an outer electrode (16) electrically connected to the outer tube (12) and an inner electrode (18) electrically connected to the inner tube (14), wherein the inner electrode (18) comprises a conductor (20) and a plurality of an conductive granulated material (22) for providing an electrical contact between the conductor (20) and the inner tube (14). Due to the conductive granulated material (22) an electrical contact between the conductor (20) and the inner tube (14) is safeguarded and different thermal expansions of the inner electrode (18) and the inner tube (14) are compensated at the same time without applying mechanical stress to the inner tube (14). This leads to a dielectric barrier discharge lamp (10), which comprises an increased life time without the need for external cooling.

Claims

1. Dielectric barrier discharge lamp for providing ultraviolet light, comprising

an outer tube (12) filled with a discharge gas for providing ultraviolet light,

an inner tube (14) arranged at least partially inside the outer tube (12),

an outer electrode (16) electrically connected to the outer tube (12) and

an inner electrode (18) electrically connected to the inner tube (14),

wherein the inner electrode (18) comprises a conductor (20) and a plurality of a conductive granulated material (22) for providing an electrical contact between the conductor (20) and the inner tube (14).

2. Lamp according to claim 1, wherein the inner electrode (18) fills a volume inside the inner tube (14) by a portion p of 5%≦

p≦

95%, particularly 30%≦

p≦

90%, preferably 60%≦

p≦

85%.

3. Lamp according to claim 1, wherein the amount of the granulated material (22) is below the percolation threshold with respect to a volume inside the inner tube (14) and/or with respect to the electrical conduction in axial direction along the inside of the inner tube (14).

4. Lamp according to claim 1, wherein the inner tube (14) comprises an axial proximal end and an axial distal end (26), wherein only the proximal end is fixed to the outer tube (12) for sealing the discharge gas outside the inner tube (14) and inside the outer tube (12).

5. Lamp according to claim 1, wherein the outer tube (12) comprises at least one, particularly at least three grooves (30) for supporting the inner tube (14).

6. Lamp according to claim 5, wherein the groove (30) is obtainable by heating a part of the outer tube (12) and forming the heated part inwards by a negative pressure inside the outer tube (12).

7. Lamp according to claim 1, wherein the outer tube (12) comprises a distal front face (34) comprising a particularly tubular protrusion (32) for supporting an axial distal end (26) of the inner tube (14), wherein the protrusion (32) is directed inwards and/or outwards.

8. Lamp according to claim 1, wherein the inner tube (14) comprises an axial proximal end closed by a sealing (28) allowing an escape of gaseous components and preventing an escape of the granulated material (22).

9. Lamp according to claim 1, wherein the granulated material (22) is provided as powder and/or sand and/or suspension, wherein the particles of the granulated material (22) comprise a volume equivalent sphere diameter d of particularly 1.00 mm≦

d≦

0.001 mm, preferably 0.50 mm≦

d≦

0.007 mm, more preferred 0.30 mm≦

d≦

0.01 mm and most preferred 0.20 mm≦

d≦

0.07 mm.

10. Lamp according to claim 1, wherein an outer diameter d_a of the outer tube (12) is d_a=15 mm±

2.0 mm and an outer diameter d_i of the inner tube (14) is 1.0 mm≦

d_i≦

8.0 mm, particularly 2.0 mm≦

d_i≦

6.0 mm, preferably 3.0 mm≦

d_i≦

5.0 mm and most preferred d_i=4.0 mm±

0.75 mm.