Abstract: A DC/AC converter for igniting and supplying a gas discharge lamp (1). The converter has two input terminals (C, D) intended to be connected to a DC voltage source, said input terminals (C, D) being connected together by means of a series arrangement including a load circuit comprising at least an induction coil (10) and a parallel arrangement of the lamp and a capacitor (12), as well as a first semiconductor switching element (13). The load circuit is shunted by a circuit comprising a second semiconductor switching element (14). The semiconductor switching elements (13, 14) are rendered alternately conductive and non-conductive by means of control circuits (13a, 14a). A second capacitor (11) is arranged in series with the induction coil (10) and the lamp. The second capacitor is shunted by a third switching element (15) which is non-conductive during the pre-heat period of the lamp electrodes (2, 3) and is conductive at least during ignition of the lamp.

Abstract: A DC/AC converter for igniting and supplying a gas discharge lamp (1) has two input terminals (C, D) intended to be connected to a DC voltage source. These input terminals are connected together by means of a series arrangement of a load circuit comprising at least the discharge lamp (1) and an induction coil (8), as well as a first semiconductor switching element (9). This load circuit being shunted by a circuit comprising a second semiconductor switching element (10). The switching elements (9, 10) are rendered alternately conductive and non conductive at a high frequency. The lamp is shunted by a third semiconductor switching element (12) which is conductive while the lamp electrodes (2, 3) are being pre-heated, whereafter the converter is rendered inoperative for a short period of time in order to ignite the lamp, which time is shorter than the time required to cool the lamp electrodes to below their emission temperature. The converter is thereafter rendered operative again.

Abstract: A circuit arrangement for starting and operating a gas discharge laser comprises two supply lines (4,5) adapted to supply a direct current to the gas discharge laser (1). A ballast resistor (7) is connected in at least one of the supply lines. By shunting the ballast resistor with means (8) through which a starting current flows during the starting phase of the gas discharge laser, a large current flows through the laser during said starting phase so that the ionization in the laser starts readily. As a result the ignition of the laser is more reliable. The means may be a capacitor or a V.D.R.

Abstract: A dimming circuit for a discharge lamp (5) arranged in series with two electric coils (3, 4), one of which is by-passed by a semiconductor switching element (6).The control circuit of the semiconductor switching element (6) includes a series arrangement of a resistor (15) and a capacitor (16) connecting a main electrode to the control electrode. The inductance of the by-passed coil (3) is chosen such that the semiconductor switching element (6) is made conductive on reignition of the lamp. The electric losses of the dimming arrangement are low.