The invention relates to a single ended discharge lamp, such as a CID or CSI lamp having a bi-pin base. The base is such as to fit a socket suitable for lamps such as tungsten halogen filament lamps for which lower voltages are used and is adapted to make use in such sockets possible. The base or cap member is provided in the usual manner with two pins but at least one of the pins is a dummy pin. At least one extra terminal is disposed to the side of the base whereby electrical connection to one electrode of the lamp is by a flying lead. The other terminal may be the other pin or may be disposed at the other side of the base. In that event both pins may be electrically disconnected from the electrodes and serve only for support or positioning of the lamp.
The capped electric lamp of the invention has a ceramic cap (10) having a shell portion (12) and an integral base portion (11) through which metal pins (13) pass. A lamp vessel (1) having a seal (4), from which current conductors (3) to an electric element (2) within the lamp vessel extend beside one another to the exterior, is fixed in the cap (10). Outside the lamp vessel the current conductors (3) each have a portion sealed in a glass envelope (6) which is connected to the seal. The glass envelopes (6) define a slit (5) between them. A ceramic partition wall (20) having a foot (21) is fixed on the base portion (11) and extends into the slit (5), thereby creating for the current conductors and respective contact members connected thereto their own compartment (14) in the cap. The lamp cap (10) and the partition wall (20) are readily obtainable and easy to assemble and nevertheless allow for high voltages to be used to ignite or to hot restrike the lamp.
To insure orientation of internal current leads (9, 10; 23, 24) extending om a press seal (14, 27) at the end of a bulb (3, 28) inwardly thereof, small metal elements (19, 20; 31, 32), preferably of the same material as the inwardly extending current leads, are connected, for example by welding, to the inwardly extending current leads, the small metal elements being oriented to extend transversely to the major direction of the current leads and positioned in a plane determined by the plane of the press seal.
To improve the high-voltage flash-over resistance by increasing the lead aration of the lamps, the pinch or press seal is, while the lamp is being made and the lamp tubing is in plastically deformable condition, extended at least is the region adjacent the end of the later formed pinch seal by introducing spreader jaws, either parallel or, at least eventually, in acutely angled relation to each other into the softened end portion, and then spreading apart the jaws so that, at the outer end portions of the jaws, the plastically deformable region will assume an oval shape whose longer dimension is wider than the outer diameter of the tubing in the region which will later from the discharge vessel.
To increase the high-voltage resistance of a metal halide high-pressure dharge lamp, the external leads (6, 6', 6") are spaced wider apart than previously at their exit point from a pinch seal (3', 23', 23"). To facilitate manufacture, and to permit the widened spacing of the electrodes, the lamp portion (3) which will form the pinch seal is pre-heated in a first step and deformed into elongated oval cross section, leaving enough space to introduce a subassembly formed of the electrode connecting leads (6), internal electrodes (7) and molybdenum sealing foils (9); the sealing foils (9) may then already be located with a spacing which is increased with respect to spacing usually customary in the prior art. The external connecting leads (6) are secured to the sealing foils (9) so that attachment points extend at right angle to the sealing foils; the attachment leads can be angled within the press seal (FIG. 1e) or the angled portions of the connecting leads (6') can extend through lateral slits formed in the press seal outside of the lamp, to be then angled off (FIG. 2b) or to extend laterally (FIG. 2c) from the pinch or press seal (3', 23', 23").
A discharge lamp has a lamp assembly including a discharge lamp unit with a pair of lamp leads extending therefrom, and a base assembly including a pair of base leads electrically connected to the pair of lamp leads and mechanically supporting the lamp unit in position with respect to the base assembly. The base assembly comprises a hollow base structure of electrically insulating material molded in one piece with a partition dividing the interior thereof into a pair of completely isolated spaces. Electrically connected to the base leads, a pair of sheet metal conductors are received with clearances in the respective isolated spaces in order to preclude the possibility of an electric discharge taking place between the pair of conductors within the base structure.