Abstract: The invention proposes a dielectric barrier discharge lamp having a phosphor mixture and improved color rendering. The phosphor mixture comprises at least the phosphor components A: cerium-activated yttrium aluminate (Y3Al5O12:Ce) and B: europium-activated barium magnesium aluminate (BaMgAl10O17:Eu). To further improve the color rendering and to match the emission spectrum to the spectral sensitivity of film, the phosphor mixture optionally also comprises the phosphor component C: cerium- and manganese-activated gadolinium magnesium zinc pentaborate (Gd(Zn,Mg)B5O10:(Ce, Mn)) and/or the phosphor component D: europium-activated strontium aluminate (Sr4Al14O25:Eu).

Abstract: The invention proposes a dielectric barrier discharge lamp having a phosphor mixture and improved color rendering. The phosphor mixture comprises at least the phosphor components A: cerium-activated yttrium aluminate (Y3Al5O12:Ce) and B: europium-activated barium magnesium aluminate (BaMgAl10O17:Eu). To further improve the color rendering and to match the emission spectrum to the spectral sensitivity of film, the phosphor mixture optionally also comprises the phosphor component C: cerium- and manganese-activated gadolinium magnesium zinc pentaborate (Gd(Zn,Mg)B5O10:(Ce, Mn)) and/or the phosphor component D: europium-activated strontium aluminate (Sr4Al14O25:Eu).

Abstract: To prevent ion migration from a discharge vessel (4) into an evacuated sp between the discharge vessel and an outer bulb (1), a shield wire (13) is interposed between the current supply lead (12) extending longitudinally within the outer bulb and the discharge vessel (4), and both the shield wire (13) and the current supply (12) are insulated by a high dielectric insulating material. A suitable material is a ceramic, like Al.sub.2 O.sub.3 or Ba.sub.2 TiO.sub.4, for example, as a single ceramic body with ducts for, respectively, the current supply lead (12) and the shielding wire (13), or, alternatively, to form separate ceramic sleeves (17, 18).

Abstract: To reduce the axial length of high-power, high-pressure discharge lamps, for example between 1000-4000 W rating, while reducing the temperature, in operation, of a connection foil (8) adjacent the base ends of the foil, the discharge vessel (2) of quartz glass has two shaft-like extensions (5) unitary therewith, in which the connection foils are pinch or press-sealed. The lengths of the pinch or press seals are major fractions of the length of the discharge of the discharge vessel, for example between 2/3 and 4/3 thereof, and the connection foil extends over a major portion of the length of the shaft-like extension, for example between 60-80%. Such pinch seals are made by differentially, over its length, heating the shaft-like extension (5).

Abstract: To make a small high-pressure discharge lamp, for example of 50 W rating or less, and suitable, for example, for automotive applications, a quartz glass tube is heated, formed with constrictions, and a gas passed therebetween to expand the portion of the tube between the constrictions into olive shape to form the discharge vessel (6). A preformed first electrode system is introduced through one of the constrictions. The electrode system preferably has a zig-zag lead (9) slightly larger than the internal diameter of the tube to provide for self-centering. The tube is then isolated from atmosphere, for example by being placed in a glove box or coupled to a pumping head (15), for introduction therein of a fill substance, for example in pellet form, of a metal halide and, if desired, mercury; and a fill gas, such as argon or, preferably, xenon, preferably after cleaning and flushing the tube.

Abstract: To shorten the time between firing of a high-pressure discharge lamp and stantial light output therefrom, the discharge lamp includes a fill of xenon, at a cold fill pressure of at least 3 bar, in addition to mercury and a metal halide; the discharge vessel (2) is, at least in part, coated or doped so that invisible radiation is reflected into the lamp, or absorbed, while visible radiation is being transmitted by the discharge vessel. The shafts of the electrodes are thin, of only about 0.3 mm diameter, and the electrodes facing each other are part-spherical or rounded. The lamp is operated in combination with a lamp power supply (S) which has the characteristics of being capable of supplying between 5 to 10 times normal operating current of the lamp under starting conditions.

Abstract: To improve the heat distribution of the electrodes within a high-pressure discharge vessel, particularly a vehicle (1) of quartz glass having a fill of mercury, a noble gas, and an additive which includes a metal or metal halide, especially, for good color rendition, tin which attacks the electrodes, the electrodes (4, 5) are pinch-sealed through the quartz glass envelope and include a parallel shaft portion (15, 17, 21) to which pin elements (16, 18, 19) are attached, for example by welding, which have a cross-sectional area larger, preferably by a factor of between 1.5 to 3, than the cross-sectional area of the shaft portion, to obtain high heat capacity of the electrodes while minimizing heat transfer to the pinch or press seal of the electrodes through the quartz glass vessel (2) via the shaft portions.

Abstract: To permit use of a metal halide discharge lamp for general service illumiion requiring a color temperature of below 4100 K., and preferably about 4000 K., or even less, for example about 3500 K., a metal halide discharge lamp is fitted into a reflector and closely surrounded by a closed transparent tube of hard glass or quartz glass, which may be coated with an indium-tin-oxide (ITO) layer. The surrounding tube is retained against the base structure of the lamp adjacent the reflector apex, or fitted against the reflector, and closed at the other end either by an end cap integral with the tube, or by a separate cap element, retrained in position by a bridging strip spanning the light exit opening of the reflector. Preferably, the reflector is faceted.

Abstract: To improve the heat distribution of single-ended metal-halide high-pressure discharge lamps, and particularly lamps in which the fill is apt to attack a helically wound electrode (4) facing a similar electrode (5) within a discharge vessel (2), the end portions of the electrodes have a mandrel or pin element (17) located within a plurality of coiled windings (16), such that the coiled windings of the electrodes surround the mandrel or pin elements (17). Preferably, the mandrel is made of thorium dioxide-doped tungsten, and the electrodes includes an electrode shaft portion (15) pinch-sealed through the quartz-glass vessel. The shaft portions are unitary with the coiled windings (16) and are made of undoped, essentially pure tungsten.

Abstract: To provide for preheating of a high-pressure discharge lamp (6) having a charge vessel (7) closed off by a pinch or press seal (8), a ceramic holder (1), typically a ceramic tube with multiple capillary openings therein, has a heating wire threaded through the capillary openings, and the ceramic holder is located in intimate thermal transfer with respect to the lamp, for example by being placed and cemented in the transition zone between the discharge vessel (7) and the pinch or press seal. Heater power of about 10 W applied to two such ceramic capillary heaters located adjacent both sides of the pinch or press seal permits preheating the fill of the lamp so that 40% of rated light output can be obtained within several seconds after energization of the electrodes. The lamp is suitable as a headlamp for vehicular use and can be constructed in miniature size, with a discharge vessel volume in the range of 100ths cm.sup.3.

Abstract: To provide for a long electrode shaft, which insures rapid and reliable sting of the lamp, the electrodes are formed with a straight shaft portion extending from a pinch or press seal (8) and then twisted into a loop (20, 21) which terminates in discharge tips (18, 19), facing each other across the center line of the lamp. The loops, preferably, include a circular portion of about 270.degree., with a radius of greater than the radius of the diameter of the wires--typically of tungsten--and offset with respect to the electrode shaft so that, at cross-over points (24, 25) the looped portion (20, 21) of the respective electrode and the straight or shaft portion (22, 23) of the electrode do not touch each other; a very small spacing, for example 0.05 mm, with electrode wires of 0.2 mm diameter, is sufficient.

Abstract: To provide for pre-heating of low-power small metal halide high-pressure charge lamps (1), at least one of the electrodes (16) is formed as a heater wire by introducing a thin tungsten wire, in V shape, into one end of the elongated bulb (2), and carrying out each one of the legs of the V, separately, and electrically insulated within an end press seal (4) by parallel foils (10, 11) externally of the bulb. Continuous heater current is caused to flow through the V-shaped wire electrode, thus heating the discharge vessel, to complete vaporization of the fill. To start the lamp, the two legs of the V, of the heater electrode, are connected in parallel and across the lamp operating voltage and then a high-voltage pulse is applied between the V-shaped heater electrodes, for example between one or both of the external conductors and the other electrode (9). Light output, upon starting, is substantially accelerated from a lamp of this type with respect to non-preheated lamps.

Abstract: To improve the high-voltage flash-over characteristics of high-pressure dharge lamps (1), and especially to prevent flash-over between terminal leads emanating from the lamp bulb and extending into a lamp base (14), the lamp base which is formed with a cup-shaped opening (13) has an insert pad (18) placed therein of fibrous web, pile, fleece or mat material, made of ceramic, quartz or glass fibers. In manufacture, the fibers are compressed, thereby fitting tightly against the terminal end, typically a pinch or press seal, of the discharge lamp bulb, and thereby substantially increasing the high voltage flash-over resistance between the terminal leads and permitting hot re-ignition of the lamp, which may require pulses of between 15 to 20 kV.

Abstract: 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.

Abstract: 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.

Abstract: Low-power lamps, that is, lamps having a power rating of less than 250 W, g. less than 100 W, and, for instance 40 W, have an arc tube which has a fill of mercury with additives of metal halides and a noble gas. To permit universal mounting application of the lamp, the arc tube (2) has a single-press seal (3) at one side thereof in which the electrodes are retained, the arc tube being surrounded by an envelope having, likewise, a single-ended, single-press seal (5) located at the same side as the press seal of the arc tube, through which continuation elements (8, 10, 12, 14; 9, 11, 13, 15) of the electrode elements are conducted. The arc tube and the envelope are so closely spaced that heat radiated from the arc tube to the envelope is effectively reflected to the arc tube without substantial radiation by the envelope. The arc tube and/or the envelope may be frosted, and made, respectively, of hard glass or quartz glass which has low transmissivity in the UV and IR ranges of radiation.

Abstract: 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.

Abstract: A high-pressure discharge lamp with metal halide additives and a power in of less than 100W comprises electrodes (4, 5) which have a shank portion (18) adjacent the seal and a second portion (19) which is formed as a coil and faces the discharge. Adjacent turns of the coil portion (19) do not contact one another. Shank (18) and coil (19) are preferably made of a single piece of wire. In the case of a double-ended arc tube (FIGS. 1 and 2) the axis of the coil portion (19) forms a substantially straight line with the shank portion (18). In the case of a single-ended arc tube (FIGS. 3 and 4) the axis of the coil portion includes an angle of 90.degree. with the axis of the shank portion. In order to protect the electrode, and especially the shank portion from corrosion, the shank (18) of the electrode (4, 5) is surrounded by a conical filament (17) of refractory metal e.g. tungston whose turns are lying closely together.