Abstract: A tubular fluorescent lamp (2) comprises an electrode (8) mounted inside the glass tube (4) which is at least partly surrounded by an electrode cover (16) mounted inside the glass tube (4) and situated between the electrode (8) and the wall of the glass tube (4) at a distance from them. According to the invention, a spacer (24) is placed in such a way that when the electrode cover (16) unintentionally is moved from its mounting position in a radial direction relative to the longitudinal axis of the glass tube (4), contact occurs between the electrode cover (16) and the spacer (24), and between the spacer (24) and the inside of the wall of the glass tube (4), preventing the movement of the electrode cover (16) before it comes into direct contact with the inside of the wall of the glass tube (4). Thereby is prevented that the tubular fluorescent lamp cracks and may fall out from its fittings. The spacer is preferably a mica plate (24) with larger diameter than the electrode cover (16).

Abstract: An encapsulated fluorescent tube comprises an inner tube provided on its inside with a fluorescing substance layer, and an outer transmission tube which coaxially surrounds the inner tube. On its inside the outer tube is provided with two diffuser layers, situated diametrically opposite each other and extending in the longitudinal direction of the tube. The layers extend over a peripheral angle (&agr;) of between 50° and 120°. The transmission factor of each layer is highest by its longitudinal edges and lowest by its center situated between tile edges. The diffuser layers are furthermore reflective with the lowest reflection factor at the edges of the layers and the highest reflection factor at the center of the layers. Extremely even light distribution can in this way be obtained in the plane parallel with the central plane (Y—Y) between the diffuser layers, for example, the sides of signs in double-sided light signs.