Patent ID: 7573184

Claim:
A heat retaining sleeve for at least one linear fluorescent lamp having a lamp body and lamp ends, wherein a cold spot exists at one of the lamp ends and a hot spot exists in the lamp body inboard of said cold spot, said heat retaining sleeve comprising a base end, and a sleeve body extending from said base end and terminating at a distal end, said sleeve body having an inner surface and being sized and shaped to fit over and cover the lamp end of the at least one fluorescent lamp where the cold spot exists without substantial touching of the lamp end, and being sized and shaped to create a heat retaining air gap between the inner surface of said sleeve body and the lamp end of the at least one fluorescent lamp where the cold spot exits wherein the air gap extends over the lamp's cold spot, said sleeve body being short enough so that, when the sleeve is fitted over the lamp end where the cold spot exists, the distal end of said sleeve body does not extend substantially beyond the hot spot of the at least one fluorescent lamp which is inboard said cold spot, yet is long enough so that, when the sleeve is fitted over such lamp end, the cold spot of the at least one fluorescent lamp is elevated to a temperature that increases the lumen output of the at least one fluorescent lamp.