Abstract: A discharge lamp lighting device includes a discharge lamp that is lighted through an L-C resonance induced by an oscillation output of an inverter circuit. An on-off operation of switching elements of the inverter circuit is controlled by a control IC which includes a timer circuit for determining a timing of conversion between operation status signals, an inverter control circuit for outputting a driving signal to the switching elements, an output control circuit for controlling generation of the driving signal and an operation status output circuit for outputting a status signal corresponding at least to a lighting status. Further, the discharge lamp lighting device includes an operation setting circuit for inputting a status signal from the operation status output circuit and outputting a control signal to the output control circuit.

Abstract: A discharge lamp lighting device includes a discharge lamp that is lighted through an L-C resonance induced by an oscillation output of an inverter circuit. An on-off operation of switching elements of the inverter circuit is controlled by a control IC which includes a timer circuit for determining a timing of conversion between operation status signals, an inverter control circuit for outputting a driving signal to the switching elements, an output control circuit for controlling generation of the driving signal and an operation status output circuit for outputting a status signal corresponding at least to a lighting status. Further, the discharge lamp lighting device includes an operation setting circuit for inputting a status signal from the operation status output circuit and outputting a control signal to the output control circuit.

Abstract: A ballast circuit for a discharge lamp capable of protecting the circuit when the lamp reaches its end of life with a cost effective circuit arrangement. The circuit includes a DC voltage sensing network for sensing a DC voltage which appears as a consequence of the lamp reaching its end of life. Upon the sensed DC voltage exceeding a threshold, a control is made to limit or stop supplying an output power to the lamp for protecting the ballast circuit from an otherwise generating excessive current. The sensing network is composed of a DC sensing capacitor and a resistor which are connected in circuit outside of a resonant circuit responsible for generating a high frequency voltage to operate the lamp. Thus, the DC sensing capacitor can be kept free from the high voltage generated by the resonant circuit and be of less cost for reducing a manufacturing cost.

Abstract: A ballast circuit for a discharge lamp capable of protecting the circuit when the lamp reaches its end of life with a cost effective circuit arrangement. The circuit includes a DC voltage sensing network for sensing a DC voltage which appears as a consequence of the lamp reaching its end of life. Upon the sensed DC voltage exceeding a threshold, a control is made to limit or stop supplying an output power to the lamp for protecting the ballast circuit from an otherwise generating excessive current. The sensing network is composed of a DC sensing capacitor and a resistor which are connected in circuit outside of a resonant circuit responsible for generating a high frequency voltage to operate the lamp. Thus, the DC sensing capacitor can be kept free from the high voltage generated by the resonant circuit and be of less cost for reducing a manufacturing cost.