Abstract: The present invention relates to an Electronic ballast for operating a high-pressure discharge lamp, comprising a switched-mode power supply circuit (SMPS) for supplying a rail voltage Vrail to the high pressure discharge lamp, the power supply circuit comprising a half bridge commutating forward circuit including an inductance (Lhbcf), a capacitor circuit of a first capacitor (Cs1) and a second capacitor (Cs2) in series, the lamp (LA) being connectable between the inductance (Lhbcf) and a midpoint (M) between the first and second capacitor (Cs1,Cs2); a duty cycle control circuit, connected to the switched-mode power supply circuit, for controlling the duty cycle of the half bridge commutating forward circuit; and overvoltage protection means for protecting said capacitors against overvoltage, comprising—a midpoint voltage detection circuit for detecting the voltage at the midpoint between the first and second capacitor, the midpoint voltage detection circuit providing a first signal representative of the det

Abstract: The present invention relates to a device for operating a high-pressure discharge lamp, comprising a switched mode power supply circuit (SMPS) for supplying power to the high pressure discharge lamp from a supply voltage, the power supply circuit comprising a half bridge commutating forward (HBCF) circuit including an inductance(Lhbcf?), a capacitor circuit of a first capacitor (Cs1) and a second capacitor (Cs2) in series, the lamp (LA) being connectable between the inductance (Lhbcf) and a point (M) between the first and second capacitor (Cs1,Cs2); wherein overvoltage protection means are connected parallel to the lamp, which switch from an off-state with a high resistance operation to an on-state with a low resistance operation when the voltage difference across the protection means exceeds a breakover voltage (Vbo), the breakover voltage (Vbo) being selected to correspond to a predetermined maximum voltage across the first or the second capacitor (Cs1,Cs2).

Abstract: The present invention relates to a device for operating a high-pressure discharge lamp, comprising a switched mode power supply circuit (SMPS) for supplying power to the high pressure discharge lamp from a supply voltage, the power supply circuit comprising a half bridge commutating forward (HBCF) circuit including an inductances (Lhbcf?), a capacitor circuit of a first capacitor (Cs1) and a second capacitor (Cs2) in series, the lamp (LA) being connectable between the inductance (Lhbcf) and a point (M) between the first and second capacitor (Cs1,Cs2); wherein overvoltage protection means are connected parallel to the lamp, which switch from an off-state with a high resistance operation to an on-state with a low resistance operation when the voltage difference across the protection means exceeds a breakover voltage (Vbo), the breakover voltage (Vbo) being selected to correspond to a predetermined maximum voltage across the first or the second capacitor (Cs1,Cs2).

Abstract: The present invention relates to an Electronic ballast for operating a high-pressure discharge lamp, comprising a switched-mode power supply circuit (SMPS) for supplying a rail voltage Vrail to the high pressure discharge lamp, the power supply circuit comprising a half bridge commutating forward circuit including an inductance (Lhbcf), a capacitor circuit of a first capacitor (Cs1) and a second capacitor (Cs2) in series, the lamp (LA) being connectable between the inductance (Lhbcf) and a midpoint (M) between the first and second capacitor (Cs1,Cs2); a duty cycle control circuit, connected to the switched-mode power supply circuit, for controlling the duty cycle of the half bridge commutating forward circuit; and overvoltage protection means for protecting said capacitors against overvoltage, comprising—a midpoint voltage detection circuit for detecting the voltage at the midpoint between the first and second capacitor, the midpoint voltage detection circuit providing a first signal representative of t

Abstract: The invention relates to a circuit for operating a high-pressure discharge lamp, which circuit is provided with means for operating the connected lamp in a dimmed state by means of a dimming signal Ds. The circuit is provided with: input terminals for connecting the circuit to a power supply source, output terminals for connecting the lamp to be operated, a switch-mode power supply (smps) having a converter provided with a semiconductor switch for generating a converter output voltage across buffer capacitor means, and a control circuit for generating a control signal in dependence on the dimming signal Ds for controlling the semiconductor switch. According to the invention, the circuit is further provided with means for generating a converter output voltage-related signal Lvs for monitoring stable lamp operation by limiting the dimmed state by means of the control circuit.

Abstract: A circuit for operating a high-pressure discharge lamp with successive current periods, which circuit is provided with means for operating the connected lamp by means of a dimming signal Ds from a first state to a second state, which circuit is further provided with: input terminals for connecting the circuit to a power supply source, output terminals for connecting the lamp to be operated, a switch-mode power supply (smps) having a converter with a semiconductor switch for generating a converter output voltage across buffer capacitor means having a capacitance, and a control circuit for generating a control signal which is intended to control the switch and depends on the dimming signal. The circuit is provided with means for adjusting the capacitance of the buffer capacitor means.

Abstract: The invention relates to a circuit for operating a high-pressure discharge lamp, which circuit is provided with means for operating the connected lamp in a dimmed state by means of a dimming signal Ds.

Abstract: The invention relates to a circuit for operating a high-pressure discharge lamp with successive current periods, which circuit is provided with means for operating the connected lamp by means of a dimming signal Ds from a first state to a second state, which circuit is further provided with: