Fluorescent lamp with adjustable color temperature

Abstract

A fluorescent lamp having an adjustable color temperature comprising at least two elongated fluorescent discharge tubes (10 & 20), one tube (10) having a larger diameter than the other (20). The tubes (10 & 20) are assembled into a single unit. A groove (12) is disposed within the larger tube (10) and runs parallel to the longitudinal axis. The smaller diameter tube (20) is snugly nested within the groove (12) and in intimate contact with the larger diameter tube (10). The larger diameter tube has a phosphor coating producing one color temperature and the smaller diameter tube produces a different color temperature. Preferably, the larger tube has a phosphor coating that emits a low color temperature of 3000.degree. K. or below and the smaller tube's phosphor coating emits a high color temperature of greater than 10,000.degree. K. A controller divides the power to the two tubes such that a variable color temperature is produced at nearly constant total power.

Dependencies are inferred from the claim text.