Patent ID: 7477005
Filing Date: 2009-01-13
Classification: H01J

Abstract:
1. A fluorescent lamp with a thermally-insulating assembly comprising: an elongated glass tube having an interior and an exterior and first and second opposed ends, mercury being disposed within the interior of the elongated glass tube and a cold spot present within the elongated glass tube that substantially controls the vapor pressure of the mercury; a first cathode stem affixed to the elongated glass tube at the first end of the elongated glass tube, one end of the first cathode stem extending into the interior of the elongated glass tube a first distance; a second cathode stem affixed to the elongated glass tube at the second end of the elongated glass tube, one end of the second cathode stem extending into the interior of the elongated glass tube a second distance, the second distance being sufficiently greater than the first distance, and the elongated glass tube having an internal diameter, such that the cold spot within the elongated glass tube is located within a portion of the elongated glass tube that is nearer the second end of the glass tube than the first end of the elongated glass tube; and a band of a thermally-insulating material located at the exterior of the elongated glass tube and substantially surrounding the portion of the elongated glass tube where the cold spot is located whereby the cold spot is insulated from the ambient environment.