Abstract: A high-pressure mercury vapor discharge lamp has an envelope which contains two electrodes made from tungsten and a filling in a discharge space. The filling essentially consists of mercury, rare gas, and a halogen that is free in the operating condition. The envelope further has a second space.

Abstract: A high-pressure gas discharge lamp with a cooling arrangement is described, which is characterized in particular in that the lamp can be operated at an increased power, an increase in the temperature of the coldest spot in the lamp interior generating a higher gas pressure, while the cooling arrangement (7, 71, 83, 82) is constructed and dimensioned such that a devitrification of the lamp bulb and a condensation of the filling gas are substantially prevented at said increased power. A lighting unit with such a high-pressure gas discharge lamp is further described, as is a power supply unit for operating the lamp. This not only considerably improves the spectral properties of the light, but the lamp also operates at a higher operating voltage because of the higher gas pressure, so that a correspondingly higher lamp power is achieved for a given lamp current. On the other hand, given the same lamp power, a weaker current is required, so that the electrodes will have a substantially longer useful life.

Abstract: A method of and a device for operating a gas discharge lamp which is fed with an alternating voltage or an alternating current and wherein the instantaneous power of the lamp is increased at given time intervals are used to form the electrodes. The value of an operational datum of the lamp which varies in time is continuously or discontinuously measured and the frequency of the alternating voltage or the alternating current (operating frequency) is selected in dependence on the measured values.

Abstract: A high-pressure gas discharge lamp (HID or UHP lamp, or in general lamps with mercury fillings of between approximately 0.05 and 0.5 mg/mm3) is described with at least one electrode (7, 8) which is provided with a thickened, for example globular portion (9, 10) at its end lying inside a lamp vessel (2). This portion is so dimensioned in dependence on operational parameters of the lamp and/or the diameter of the electrode rod that an electrode tip (19) forms itself independently at said portion during the first hours of operation. This tip grows from the portion until its free end starts melting. The electrode tip is self-adjusting in this manner, so that an optimum electrode interspacing is maintained throughout lamp life. Furthermore, a method of manufacturing such a lamp is described.

Abstract: A high-pressure gas discharge lamp with a cooling arrangement is described, which is characterized in particular in that the lamp can be operated at an increased power, an increase in the temperature of the coldest spot in the lamp interior generating a higher gas pressure, while the cooling arrangement (7, 71, 83, 82) is constructed and dimensioned such that a devitrification of the lamp bulb and a condensation of the filling gas are substantially prevented at said increased power. A lighting unit with such a high-pressure gas discharge lamp is further described, as is a power supply unit for operating the lamp. This not only considerably improves the spectral properties of the light, but the lamp also operates at a higher operating voltage because of the higher gas pressure, so that a correspondingly higher lamp power is achieved for a given lamp current. On the other hand, given the same lamp power, a weaker current is required, so that the electrodes will have a substantially longer useful life.

Abstract: A high-pressure gas discharge lamp (HID or UHP lamp, or in general lamps with mercury fillings of between approximately 0.05 and 0.5 mg/mm3) is described with at least one electrode (7, 8) which is provided with a thickened, for example globular portion (9, 10) at its end lying inside a lamp vessel (2). This portion is so dimensioned in dependence on operational parameters of the lamp and/or the diameter of the electrode rod that an electrode tip (19) forms itself independently at said portion during the first hours of operation. This tip grows from the portion until its free end starts melting. The electrode tip is self-adjusting in this manner, so that an optimum electrode interspacing is maintained throughout lamp life. Furthermore, a method of manufacturing such a lamp is described.

Abstract: A method of and a device for operating a gas discharge lamp which is fed with an alternating voltage or an alternating current and wherein the instantaneous power of the lamp is increased at given time intervals are used to form the electrodes. The value of an operational datum of the lamp which varies in time is continuously or discontinuously measured and the frequency of the alternating voltage or the alternating current (operating frequency) is selected in dependence on the measured values.

Abstract: A circuit arrangement is provided for operating a high pressure discharge lamp with a lamp current which, in successive periods, has opposite polarities. The lamp is provided with at least two main electrodes being spaced an electrode distance from each other. The circuit arrangement includes input terminals for connection to a supply source, output terminals for connection to the high pressure discharge lamp, and an element, coupled to the input terminals, for supplying the lamp current to the high pressure discharge lamp, which current, in successive periods, has a predetermined shape. The circuit arrangement is provided with an element for detecting a first parameter indicative of the electrode distance and forming a first signal dependent on the first parameter and with an element for reshaping the lamp current, in successive periods, in dependence of the thus formed first signal.