Abstract: A discharge lamp lighting apparatus includes: an inverter circuit including a switch circuit and a high-voltage transformer; a step-up circuit connected at the input stage of the inverter circuit; a control circuit to output a switch circuit controlling signal and a step-up circuit controlling signal; an on-off switching circuit connected at a input voltage line; and a switch signal buffering circuit connected between the control circuit and the switch circuit and adapted to relay the switch circuit controlling signal. A drive voltage is applied to the control circuit without going through the on-off switching circuit, and a drive voltage is applied to the switch signal buffering circuit via the on-off switching circuit. With such a structure, an excess rush current is inhibited from flowing into the discharge lamp thereby preventing its electrode wear and therefore increasing the product life of a lamp and enhancing reliability while achieving cost reduction and downsizing.

Abstract: There is provided a rare gas fluorescent lamp lighting apparatus including: an input power source; a transformer having a rare gas fluorescent lamp connected to the secondary side thereof; a switching element connected in series to the primary side of the transformer; and a drive block to drive the switching element. The drive block includes: a constant voltage circuit to convert the voltage of the input power source into a constant voltage as an output; a constant current circuit to output a charging current according to the voltage of the input power source; a triangular waveform oscillation circuit to increase and decrease oscillation frequency according respectively to an increase and a decrease in a voltage of the input power source; and a comparison circuit to transform a triangular waveform outputted from the triangular waveform oscillation circuit into a rectangular waveform with a predetermined duty ratio as an output.

Abstract: A discharge lamp lighting apparatus includes: an inverter circuit including a switch circuit and a high-voltage transformer; a step-up circuit connected at the input stage of the inverter circuit; a control circuit to output a switch circuit controlling signal and a step-up circuit controlling signal; an on-off switching circuit connected at a input voltage line; and a switch signal buffering circuit connected between the control circuit and the switch circuit and adapted to relay the switch circuit controlling signal. A drive voltage is applied to the control circuit without going through the on-off switching circuit, and a drive voltage is applied to the switch signal buffering circuit via the on-off switching circuit. With such a structure, an excess rush current is inhibited from flowing into the discharge lamp thereby preventing its electrode wear and therefore increasing the product life of a lamp and enhancing reliability while achieving cost reduction and downsizing.

Abstract: There is provided a rare gas fluorescent lamp lighting apparatus including: an input power source; a transformer having a rare gas fluorescent lamp connected to the secondary side thereof a switching element connected in series to the primary side of the transformer; and a drive block to drive the switching element. The drive block includes: a constant voltage circuit to convert the voltage of the input power source into a constant voltage as an output; a constant current circuit to output a charging current according to the voltage of the input power source; a triangular waveform oscillation circuit to increase and decrease oscillation frequency according respectively to an increase and a decrease in a voltage of the input power source; and a comparison circuit to transform a triangular waveform outputted from the triangular waveform oscillation circuit into a rectangular waveform with a predetermined duty ratio as an output.

Abstract: In a pulse width modulation circuit, which generates an output whose pulse width is modulated by controlling a duty ratio of an oscillation circuit adapted to generate an oscillation at a frequency determined by a resistor and a capacitor to be electrically charged via the resistor, there is provided a resistance value varying means to vary a value of the resistor. The value of the resistor is varied by shorting the both ends of the resistor with a transistor, whereby the capacitor is charged in a reduced amount of time realizing a high-speed pulse width modulation circuit.

Abstract: In a pulse width modulation circuit, which generates an output whose pulse width is modulated by controlling a duty ratio of an oscillation circuit adapted to generate an oscillation at a frequency determined by a resistor and a capacitor to be electrically charged via the resistor, there is provided a resistance value varying means to vary a value of the resistor. The value of the resistor is varied by shorting the both ends of the resistor with a transistor, whereby the capacitor is charged in a reduced amount of time realizing a high-speed pulse width modulation circuit.

Abstract: A discharge lamp lighting circuit includes an open-circuit protection means to protect a driving means when a discharge lamp is not lighted. The open-circuit protection means is adapted to send out to a control means a signal for limiting a current flowing in the driving means to or below a predetermined value when the tube current is equal to or lower than a first value predetermined, and a signal for sequentially increasing a current flowing in the driving means up to a rated current when the tube current is higher than the first value and also is equal to or lower than a second value predetermined, and to stop a driving signal sent from the control means when a tube current flowing in the discharge lamp has a value equal to or lower than the first value after a predetermined time.

Abstract: A discharge lamp lighting circuit includes an open-circuit protection means to protect a driving means when a discharge lamp is not lighted. The open-circuit protection means is adapted to send out to a control means a signal for limiting a current flowing in the driving means to or below a predetermined value when the tube current is equal to or lower than a first value predetermined, and a signal for sequentially increasing a current flowing in the driving means up to a rated current when the tube current is higher than the first value and also is equal to or lower than a second value predetermined, and to stop a driving signal sent from the control means when a tube current flowing in the discharge lamp has a value equal to or lower than the first value after a predetermined time.

Abstract: In a pulse width modulation circuit, which generates an output whose pulse width is modulated by controlling a duty ratio of an oscillation circuit adapted to generate an oscillation at a frequency determined by a resistor and a capacitor to be electrically charged via the resistor, there is provided a resistance value varying means to vary a value of the resistor. The value of the resistor is varied by shorting the both ends of the resistor with a transistor, whereby the capacitor is charged in a reduced amount of time realizing a high-speed pulse width modulation circuit.