摘要:
A burst dimming signal to determine a ratio between an ON period and an OFF period is inputted. In the OFF period of the burst dimming signal, a lamp current Ila is stopped from flowing to a discharge lamp FL, while a lamp voltage Vla is applied to both ends of the discharge lamp FL, and preheating currents If1 and If2 are supplied to hot cathodes of the discharge lamp FL. In the ON period of the burst dimming signal, the discharge lamp FL is electrically broken down and is supplied with the lamp current Ila.
摘要:
A burst dimming signal to determine a ratio between an ON period and an OFF period is inputted. In the OFF period of the burst dimming signal, a lamp current Ila is stopped from flowing to a discharge lamp FL, while a lamp voltage Vla is applied to both ends of the discharge lamp FL, and preheating currents If1 and If2 are supplied to hot cathodes of the discharge lamp FL. In the ON period of the burst dimming signal, the discharge lamp FL is electrically broken down and is supplied with the lamp current Ila.
摘要:
A power source device is so constituted that a first capacitor connected across DC output terminals of a rectifier is made to be of a relatively small capacity, a resonance circuit is formed by a primary winding of a transformer and a second capacitor, first and second switching elements connected in parallel to a smoothing capacitor are alternately made ON and OFF to cause currents to flow, a both-end voltage of the first capacitor drops to be substantially close to zero volt even in a period in which a source voltage of an AC power source becomes substantially zero, and an input current can be drawn in smoothly over the entire range of a cycle of the source voltage of the AC power source, whereby higher harmonics of the input current can be reduced, a pulsation of the current flowing to a load can be minimized, and required number of parts for the power source device is reduced to be able to realize circuit simplification and cost reduction.
摘要:
An electronic ballast for a discharge lamp is capable of dimming the lamp over a wide range, yet minimizing a color temperature deviation. The ballast includes a power converter which converts an input DC voltage into a lamp power for driving the lamp, and a dimmer providing a dimmer command of a varying dimming ratio in order to reduce the lamp power to a greater extent as the dimming ratio decreases. A controller controls the power converter to supply a high frequency AC current to the lamp in response to the dimming ratio decreasing to a predetermined level, and to reduce an RMS value of the high frequency AC current as the dimming ratio decreases past the predetermined level.
摘要:
An inverter device includes a rectifier for rectifying an AC voltage produced by an A.C. power source; an inverter circuit receiving a first DC output voltage and outputting a high frequency voltage for operating a load circuit; and auxiliary power supply means including a smoothing capacitor connected across the rectifier for smoothing current supplied to the load circuit, wherein the inverter circuit includes DC/DC converter receiving the first DC output voltage, for outputting a second DC output voltage less than a peak value of the first DC output voltage, and DC/AC converter receiving the second DC output voltage for outputting the high frequency voltage, the DC/DC converter and DC/AC converter sharing a common switching element, the DC/AC converter receiving a DC voltage less than the voltage produced by the A.C. power source.
摘要:
An illumination load determination device includes an illumination load; a voltage applying unit for applying a voltage to the illumination load; a connection unit for connecting the illumination load and the voltage applying unit; a detection unit for detecting at least one of a current flowing through the illumination load and a voltage across the illumination load when the voltage is applied to the illumination load from the voltage applying unit via the connection unit; and a determination unit for determining a type of the illumination load based on an output from the detection unit. The determination unit has a comparator for comparing a detection value detected by the detection unit to a predetermined threshold, and determines that the illumination load has a capacitance based on an output of the comparator. The voltage applying unit lights on the determined illumination load with a rated driving voltage.
摘要:
A lighting power source provides AC or DC power as needed to power an electric light source. A first switching element and a diode are coupled in series across output ends of a DC power source, with a second switching element coupled across the diode. An inductor forms an output loop with the diode. A driving capacitor has a first end coupled to a node between the first switching element and the diode. A charging power source is coupled to a second end of the driving capacitor and supplied with power from the DC power source. During a charging operation, a control circuit charges the driving capacitor by turning on the second switching element while maintaining the first switching element in an OFF state. During a normal operation which follows the charging operation the control circuit repeatedly turns on/off the first switching element while maintaining the second switching element in the OFF state.
摘要:
A lighting power source provides AC or DC power as needed to power an electric light source. A first switching element and a diode are coupled in series across output ends of a DC power source, with a second switching element coupled across the diode. An inductor forms an output loop with the diode. A driving capacitor has a first end coupled to a node between the first switching element and the diode. A charging power source is coupled to a second end of the driving capacitor and supplied with power from the DC power source. During a charging operation, a control circuit charges the driving capacitor by turning on the second switching element while maintaining the first switching element in an OFF state. During a normal operation which follows the charging operation the control circuit repeatedly turns on/off the first switching element while maintaining the second switching element in the OFF state.
摘要:
An object of the invention is to provide a high-pressure discharge lamp lighting device capable of executing dimming up to a lower luminous flux level than the dimming lower limit obtained by performing constant-current control in related arts.A high-pressure discharge lamp lighting device of the invention includes power conversion unit for supplying AC power to a high-pressure discharge lamp as a load with a DC power supply as an input power supply for performing all lighting or dimming lighting. In an area where the voltage across the high-pressure discharge lamp grows as dimming deepens, the output characteristic of the power conversion unit is a characteristic for increasing the output current of the power conversion unit in response to an increase in the output voltage of the power conversion unit. The ratio of the increase in the output current to the increase in the output voltage is made roughly constant or the ratio of the increase in the output current to the increase in the output voltage is made larger as dimming becomes deeper.
摘要:
An object of the invention is to provide a high-pressure discharge lamp lighting device capable of executing dimming up to a lower luminous flux level than the dimming lower limit obtained by performing constant-current control in related arts. A high-pressure discharge lamp lighting device of the invention includes power conversion unit for supplying AC power to a high-pressure discharge lamp as a load with a DC power supply as an input power supply for performing all lighting or dimming lighting. In an area where the voltage across the high-pressure discharge lamp grows as dimming deepens, the output characteristic of the power conversion unit is a characteristic for increasing the output current of the power conversion unit in response to an increase in the output voltage of the power conversion unit. The ratio of the increase in the output current to the increase in the output voltage is made roughly constant or the ratio of the increase in the output current to the increase in the output voltage is made larger as dimming becomes deeper.