Abstract: A metal-halide discharge lamp for photooptical purposes has a small electe spacing of less than 15 mm, preferably 2-8 mm, to provide an essentially pin-point light source, and a fill which contains AlI.sub.3 in an amount between 0.1 and 4.5 mg/cm.sup.3. Other filling components may in particular be halides of mercury, indium, thallium or cesium; up to 2 mg/cm.sup.3 of AlBr may be added. The lamp is particularly adapted for combination with a, preferably parabolic, reflector.

Abstract: To positively locate a filament (5, 22) in position within a bulb (2) of a halogen incandescent lamp, the walls of the bulb are deformed at selected points along the length of the filament within the bulb to define at least three inwardly projecting dimples which just barely engage, or engage, the filament. Preferably, the filament is formed with a connecting portion (7) in the region of engagement, which connecting portion is either straight, coiled with a very steep pitch, or, if the filament is double-coiled, only single-coiled. The connecting portion (7) may be electrically short-circuited by a core pin (39). If the bulb is single-ended (FIG. 3), a return lead (29) along the wall of the bulb, can be pinched between adjacent walls (45) of adjacent dimples. The dimples, looked at from the outside of the lamp, are essentially funnel-shaped and, in cross section, may be circular, or if space between adjacent dimples is insufficient, may be elliptical.

Abstract: To operate a discharge lamp, and more particularly a low-power high-pressure discharge lamp, only in quiet or stable lamp operation, a microprocessor (MC) is provided which establishes a test phase of limited time duration during which the frequency of operation of the lamp is varied by frequency modulation within a predetermined range. Lamp operation is monitored, for example by deriving a test voltage across a coupling capacitor (C6) receiving lamp current. If the monitored voltage, which is representative of lamp operation, shows that the lamp operates quietly and stably, the then pertaining frequency is stored by the microprocessor and, after the test phase is finished, the lamp is operated within a frequency window formed by the largest number of contiguous modulation frequencies which are suitable for, or result in, stable lamp operation. The test phase is carried out repetitively, at least upon each energization of the lamp, so that different operating characteristics of the lamp (e.g.

Abstract: To meet IEC regulations in accordance with IEC publication 555-2 class D, r harmonic content of feedback into power networks upon use of low-power fluorescent lamps, an operating circuit for a lamp, or serially connected lamps is provided which includes a rectifier (2), rectifying a-c input energy, and having a smoothing capacitor (C3) connected across its output (J1, J2), the output of which is inverted in a half-bridge inverter using alternately conductive transistors (T1, T2), a passive filter circuit (5) is connected between an electrode of the lamp, or the last electrode of the lamps and a return connection to the rectifier (2). The passive filter circuit (5) has two serially connected diodes (D1, D2) defining a common junction (M2), connected in d-c blocking direction in a connection line between the second electrode (E2, E4') of a lamp (LP1) or the last of a group of serially connected lamps (LP1', LP2') and one (J1) output terminal of the rectifier (2).

Abstract: To eliminate radiation from the mercury high-pressure discharge lamp of wlengths below 365 nm, the lamp includes a discharge vessel of quartz glass which is doped with vanadium in a quantity of up to about only 250 ppm, by weight, with respect to 1 mm of wall thickness of the quartz glass. This absorbed radiation also heats the quartz glass, so that the outside wall temperature of the vessel can be maintained between about 400.degree. and 950.degree. C. The effect can be enhanced by adding, additionally, titanium and/or tin to provide metal ions to the doping substance, in an overall quantity of up to 500 ppm, by weight. Alternatively, the quartz glass can be coated with TiO.sub.2 or SnO.sub.2. Suitable wall thicknesses for the discharge vessel are between 1 and 5 mm, and the fill therein is preferably mercury in a quantity of between 0.5 and 15 mg/cm.sup.3 and xenon with a cold fill pressure of 0.1 to 2.5 bar. Electrode spacing of the lamp is preferably between 2 and 5 mm.

Abstract: The glove box has a rotatably supported bottom member (2, 11, 51) which is quipped with a number of product holders (14) positioned concentrically with the rotational axis of the bottom member. The product holders receive subassemblies or precursor products to be processed, partly within and partly without the glove box. Typical precursor products are discharge vessels for discharge lamps, of small size, for example having discharge vessel volumes in the tenths and hundredths of a cubic centimeter, which are to be flushed with a flushing gas, and then filled with an ionizable fill. Rotation of the bottom member delivers the products in the product holders to work-stations at which flushing, filling and other operations are carried out inside the glove box. Simultaneously, other operations such as pinching and sealing portions of the discharge vessels can be carried out outside of the glove box by suitable outwardly located operating stations (18).

Abstract: To improve the arc stability of high-pressure discharge lamps, particularly f power ratings of up to about only 250 W, the cathode (4) is formed as an elongated, essentially cylindrical base body (8) having a tapering, conical region (9) terminating in a tip (10). The base body (8), only, is covered with a carbide coating along its length, except for an end portion for electrical connection; the carbide coating starts at the junction or transition between the cylindrical base body portion and the conical end portion. This cathode construction is easier and cheaper to make than prior art cathodes, by coating an essentially cylindrical cathode and then etching or grinding and polishing the tapering end region (9). The electrode is preferably made essentially of tungsten, doped with thorium oxide present up to about 0.6%, optionally also potassium, aluminum and silicon in tiny amounts. The electrode spacing is between 0.4 to 0.

Abstract: A ceramic discharge vessel (6) for a high-pressure discharge lamp (1) made from a sintered body of optically translucent polycrystalline alumina ceramic which is doped with only 100-800 ppm MgO, only 200-1200 ppm ZrO.sub.2 and only 10-300 ppm Y.sub.2 O.sub.3 (by weight). This improves the loading capacity and operating characteristics of the vessel and of the lamp.

Abstract: To essentially eliminate short ultraviolet (UV) radiation from a mercury high-pressure short-arc discharge lamp, that is, wavelengths below the radiation band of 365 nm, the lamp includes a discharge vessel of quartz glass which is coated with a selectively reflective outer coating (2a) and, at the inside, with a selectively absorbing inner coating (2b). The outer coating (2a) is formed by a multi-layer interference reflection filter which preferentially reflects wavelengths between about 240 and 300 nm with a filter cut-off, corresponding to 50% transmission, in the wavelength region between about 290 and 330 nm. The inner coating (2b) is a titanium dioxide coating which, preferentially, absorbs radiation below about 250 nm, with a 50% transmission at about 240 nm. In accordance with a preferred feature of the invention, a radiation absorbing titanium dioxide/silicon dioxide mixed-layer coating (2c) is applied at the outside over the multi-layer interference reflection filter (2a).

Abstract: To operate one or more serially connected low-pressure discharge lamps, tcally fluorescent lamps, a preheating circuit is provided to preheat the electrodes of the lamps (E1, E2, E3, E4), which changes from low-impedance to high-impedance state after the lamps have been preheated by controlling a semiconductor switch (Q3) in the heating circuit. In accordance with the invention, to eliminate reliance on the resistances of the lamp filaments themselves, which are subject to variation from lamp-to-lamp due to manufacturing tolerances, and later on, to changes due to aging of the lamp, and to provide for reliable switching of the semiconductor switch, a sensing impedance element (Z), which may be an ohmic resistor or a capacitor (Z', Z"), is serially connected to the switching path of the semiconductor switch (Q3) which, typically, is a field effect transistor (FET).

Abstract: To inhibit, or at least sharply attenuate, fluorescence of a quartz-glass velope (10) surrounding a light source (11), such as a halogen incandescent lamp, a high-pressure discharge lamp, or the like, when the quartz glass is subjected to ultraviolet (UV) radiation from the light source, and has been doped with a UV radiation absorbing material, typically a cerium, or cerium-titanium doping, the quartz-glass envelope is additionally doped with praseodymium or a praseodymium compound, such as praseodymium oxide or praseodymium aluminate. The pure praseodymium in the doping is, preferably, present in quantities of between about 0.008 and 1.25%, by weight, with reference to the undoped quartz glass. Barium metaborate can also be used, preferably together with praseodymium to attenuate the fluorescence.

Abstract: To control preheating current flow through a fluorescent lamp supplied from high-frequency inverter (T1, T2, A) and a series resonance circuit, an electronic switching control circuit (SC) is connected to the preheating circuit of at least one electrode filament (E1, E2, E10, E20, E11, E21, E12, E22) of one or more of the fluorescent lamps. The switching control circuit senses the voltage across the pair of terminals (T1, T1', T2, T2') of the electrode filaments, or across all the electrode filaments. Since fluorescent lamp filaments have a positive temperature coefficient of resistance, the voltage across the filaments will rise as the filament or filaments of the lamp reach electron emission temperature. This rise in voltage is sensed, for example, by a threshold circuit which may include a Zener diode, and is used to break the preheating circuit.

Abstract: A vacuum-tight seal, particularly for an arc tube or discharge vessel for a metal halide or sodium high-pressure discharge lamp, is made by forming the arc tube of transparent ceramic, typically Al.sub.2 O.sub.3, having two open ends, into which connecting plugs (3), with central openings, are sealed. Open metal tubes (4) fitting into the openings of the plugs (3) are then vacuum-tightly sintered therein. An electrode system (5, 10, 10'), forming a subassembly with a current supply lead or lead-through (6, 11, 14, 15, 20, 24) is provided, having an outer diameter fitting into the metal tube.

Abstract: To reduce heat loading of a luminaire or lamp fixture in which a halogen andescent lamp, retained in a reflector, is installed, the bulb of the halogen incandescent lamp is coated with a heat reflecting or mirror coating so that heat radiated from the filament (3) of the lamp (2, 10) is reflected from the surface of the bulb back into the bulb, rather than being directed from the filament to the reflector so that a portion of the radiation is diffusely transmitted from the lamp through an outer covering (6) thereof. If the reflector is only partially IR reflective, the remaining portion which can pass to heat the fixture or luminaire is small enough so that its temperature rise will be within an acceptable range. Thus, forwardly directed heat radiation is not focused, as is the visible light, and heat loading on an illuminated object is substantially reduced, without excessive heat loading of the fixture or luminaire.

Abstract: To permit, selectively and in accordance with safety or standardization rirements, connection of different electrical supply devices, such as extending cables or terminal posts, pins or clamps, to a single, standardized operating or accessory circuit retained on a circuit board (2) within a housing (1), the housing is formed with a connection receiving portion (5a) selectively differently constructed connection parts (3, 3') forming insert elements are provided, dimensioned and shaped to fit into the receiving portion of the housing. The connection parts, forming the insert element, thus can be constructed according to the respective safety or standardization requirements without otherwise affecting the structure of the substantially more expensive operating or accessory circuit in the housing.

Abstract: To provide an effective seal for a metal-halide discharge lamp having a ceramic discharge vessel (4), the seal is formed in multiple parts, in which a first part, adjacent the interior or discharge side of the vessel, includes a melt component (14a) which is highly resistant to attack by metal halides within the fill of the lamp. It may contain only 0-12%, by weight, of SiO.sub.2 and has a high melting point, in the order of between 1500.degree.-1700.degree. C. The melt-in region remote from the discharge side is melt-sealed by a vitreous composition (14b), devoid of pores, voids, bubbles, fissures or cracks, to form an effective, vacuum-tight seal, and protected from attack by the metal halides by the mechanically less stable seal in the first zone. The second composition has a much lower melting point, for example in the order of between 1200.degree.-1400.degree. C., and has 20-40% SiO.sub.2.

Abstract: The discharge or arc tube chamber of a low-power high-pressure discharge lamp is, in one single step, sealed and shaped by mold or form-blowing by using pinch or press jaws (30, 31) which have concave hollows (34) formed therein to clearly define the shape of the discharge vessel, and hence of the discharge or arc tube chamber, to permit reproducible results with little variation between individual lamps to be made in a single manufacturing step. Additionally, an inclined ramp-like surface can be formed at the narrow sides (14) of the pinch seal extending towards the walls (11) of the discharge chamber (3) to thereby eliminate pockets beneath the electrodes. Preferably, the electrode shafts diverge with respect to the optical axis (A) of the lamp to increase the electrode spacing, and thus permit operation at a lower operating pressure, with respect to prior art lamps.

Abstract: To insure high power factor for the operating circuit of a low-pressure discharge lamp, especially of miniature fluorescent lamps, a high-frequency active rectifier bridge (D1-D4) is provided which interrupts charging of a smoothing capacitor (C2), which smoothing capacitor supplies an inverter circuit (WR) in the switching rhythm of the inverter. A storage choke or inductance (L1), a negative feedback capacitor (CG) and an auxiliary capacitor (CS) are coupled to the high-frequency rectifier bridge (D1-D4) which, together with the inductance insure an approximately sinusoidal current being taken from a power network, with a power factor of 0.98 or higher. Preferably, the circuit includes voltage dividers (R8, R9, R11; R15, R16, R17) which are coupled to a voltage sensitive trigger circuit (DI, TH) to turn OFF alternate switching of transistors (T1, T2) of the inverter (WR) in case excess supply voltage or operating voltages of the lamp are sensed.

Abstract: To reduce the moment of inertia and eliminate variations in speed of two xial, driven shafts, in which an outer shaft (8) surrounds a central spindle (2), which is particularly important for coiling filament material used in electric lamps, the motors are formed as essentially identical permanent-magnet rotor motors, in which permanent magnets are securely affixed to the central spindle and the surrounding shaft (8), respectively, the stators of which are retained in a common housing (6). The outer shaft carries a supply reel (3) for the filament to be coiled, whereas the inner shaft carries a winding head (7) and a reciprocating deflection roller arrangement for winding the filaments. A typical speed of operation is 1.5 seconds to wind a filament and 0.2 second pause between sequential filaments. Such filaments can be used, for example, in a general-service 60 W lamp.

Abstract: To securely retain a multi-unit folded fluorescent lamp (L) having a gap d, 21d) between adjacent legs of the lamp in position in an elongated box (1'), the box is formed from a blank (1) having a top panel (15) which overlies an intermediate panel (16) of lesser width than the top panel, from which at least a first retention flap (19a) extends in a first gap between the two legs of the lamp. A second retention flap (19b) is cut, along a severing line (19c), from the intermediate panel element (16) and folded along a fold or crease line (21) to fit into the gap between other legs of the discharge vessel or discharge vessel unit of the lamp. The retention flaps (19a, 19b) retain the lamp and support the legs in case of vibration or shock due to transport.