Abstract: Disclosed is a method for driving a gas discharge lamp in at least two operation modes, including the step of applying an alternating voltage to the gas discharge lamp, the alternating voltage having a first polarity during a first time interval and a second polarity opposite to the first polarity during a second time interval. The first time interval and the second time interval are repeated alternately. During a second operation mode, the electrical power being provided to the gas discharge lamp is smaller compared to a first operation mode, and the duration of the first time interval is at least a multiple of the duration of the second time interval.

Abstract: A metal halide lamp includes a discharge vessel surrounded by an outer envelope with clearance and has a ceramic wall which encloses a discharge space filled with a filling comprising an inert gas, such as xenon (Xe), and an ionizable salt. In the discharge space, two electrodes are arranged whose tips have a mutual interspacing so as to define a discharge path between them. The ionizable salt comprises NaI, TlI, CaI2 and X-iodide wherein X is selected from the group comprising rare earth metals.

Abstract: A metal halide lamp comprising a discharge vessel enclosing a discharge space of volume V(cm) and containing an ionizable gas filling comprising Hg in a quantity of mass m(g) and at least a metal halide, wherein in said discharge space two electrodes are arranged whose tips have a mutual interspacing EA so as to define a discharge path between them, the discharge space having a length L(mm) measured along the discharge path and a largest diameter D(mm) square thereto, wherein the ratio X=L/D satisfies the relation 0.7<X<6, and, wherein 0.28 3.

Abstract: This invention describes a method for driving a gas discharge lamp (1), whereby an alternating voltage (U) is applied to the gas discharge lamp (1), the alternating voltage (U) having a first polarity during a first time interval (tf1, ts1) and a second polarity opposite to the first polarity during a second time interval (tf2, ts2). In this method, the first time interval (tf1) and the second time interval (tf2) are repeated alternately during a first operation mode. During a second operation mode, the electrical power (P) being provided to the gas discharge lamp (1) is smaller compared to the first operation mode, and the first time interval (ts1) and the second time interval (ts2) are repeated alternately, whereby in this second operation mode the duration of the first time interval (ts1) is at least a multiple of the duration of the second time interval (ts2).

Abstract: A metal halide lamp comprising a discharge vessel surrounded by an outer envelope with clearance and having a ceramic wall which encloses a discharge space filled with a filling comprising an inert gas, such as xenon (Xe), and an ionizable salt, wherein in said discharge space two electrodes are arranged whose tips have discharge path between them, with the special feature that said ionizable salt comprises NaI, TlI, CaI2 and X-iodide wherein X is selected from the group comprising rare earth metals.

Abstract: A high-pressure discharge lamp has a discharge vessel (10) enclosing a discharge space (11) which contains an ionizable filling. The discharge vessel has a first (2) and a second (3) mutually opposed neck-shaped portion provided with a pair of electrodes (6, 7) arranged in the discharge space (13). Each electrode is tubular over its entire length. Preferably, the electrodes are free from coils in the discharge space. Preferably, the electrodes extend to outside the discharge vessel. The high-pressure discharge lamp according to the invention is relatively easy to manufacture.

Abstract: To dim a high intensity gas discharge (HID) lamp an inductance is connected in series with said HID lamp. The inductance functions as a ballast. The HID lamp is supplied by a frequency adjustable AC voltage supply. Since the impedance of the inductance is dependent on the frequency of the supply voltage, the current through the inductance is dependent on said frequency. Thus, the lamp current may be controlled by changing the frequency of the supply voltage, while the voltage is kept high kept high to prevent the lamp from extinguishing. The method and circuit of the present invention are suitable for driving a number of HID lamps simultaneously. Further, the HID lamp may be dimmed to about 20% of its nominal power, depending on the type of HID lamp. Dimming may be performed substantially instantly without extinction of the lamp.

Abstract: A high-pressure discharge lamp has a discharge vessel that is enclosed, with an interspace, by an outer bulb. The end of the outer bulb is provided with a lamp cap. The lamp has an ignition circuit including a series connection of a glow starter and an ohmic impedance. The ohmic impedance is formed by a halogen incandescent lamp. The mutual orientation of the glow starter and the ohmic impedance is such that heat produced by the ohmic impedance is at least partly intercepted by the glow starter.

Abstract: A method and a device for igniting two series-connected HID lamps (1A, 1B) are described, the two HID lamps being connected in series to a single ignitor (10). The ignitor generates a high voltage ignition pulse, which is sequentially applied to the two lamps sequentially, due to a capacitive unbalance between the two lamps. In order to ensure such capacitive unbalance, a capacitor (13) may be arranged in parallel with one of the lamps (1B).

Abstract: The electric high-pressure discharge lamp has tungsten electrodes (2) in a light-transmitting lamp vessel (1) which is closed in a gastight manner. The electrodes (2) comprise an emitter, preferably in the form of an inner coiled-coil (14), which is loosely retained in a cavity (12) of a basket (6) of the electrode (2). The inner coil (14) acts as a non-oxidic emitter. The lamp retains its initial light output to a high degree throughout its life.

Abstract: The electric high-pressure discharge lamp has tungsten electrodes (2) in a light-transmitting lamp vessel (1) which is closed in a gastight manner. The electrodes (2) comprise an emitter, preferably in the form of an inner coiled-coil (14), which is loosely retained in a cavity (12) of a basket (6) of the electrode (2). The inner coil (14) acts as a non-oxidic emitter. The lamp retains its initial light output to a high degree throughout its life.