Patent ID: 7759850

Claim:
A discharge tube arrangement for a compact fluorescent lamp, the discharge tube arrangement having a central axis and longitudinal end portions, and being formed of at least one discharge tube made of glass, enclosing a discharge volume filled with a discharge gas and having a fluorescent phosphor coating disposed on an inner surface portion of the tube, the tube forming a continuous arc path and further being provided with electrodes disposed at each end of the arc path; the discharge tube arrangement comprising a first cold chamber in order to control and maintain a required mercury vapor pressure, being located in one of the longitudinal end portions of the tube arrangement; the discharge tube arrangement further comprising at least one second cold chamber being positioned between the longitudinal end portions of the discharge tube arrangement, and the at least one second cold chamber being positioned on the wall of the tube and having a cold chamber wall protruding substantially away from the central axis of the discharge tube arrangement.