Discharge-lamp lighting circuit
AssigneeKoito Manufacturing Co., Ltd.
InventorsMasayasu Ito, Akihiro Mochizuki, Hitoshi Takeda
Life of this patent
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Abstract
In a discharge-lamp lighting circuit 1, a DC-DC converter circuit 3 for boosting or lowering DC input voltage Vin from a DC power supply 2, a DC-AC converter circuit 4 for converting the output voltage of the DC-DC converter circuit to AC voltage, and a control circuit 9 for controlling the supply of electric power to a discharge lamp 6 are provided. Further, the supply of power to the discharge lamp 6 is decreased in response to the lowering of the DC input voltage when the lowering of the DC input voltage Vin is detected. The supply of power to the discharge lamp 6 is lowered as the ambient temperature rises even though the lowering of the DC input voltage Vin remains unchanged.
Claims12
A discharge-lamp lighting circuit comprising:
- a DC-DC converter circuit for boosting or lowering a DC input voltage from a DC power supply, a DC-AC converter circuit for converting an output voltage of the DC-DC converter circuit to an AC voltage, and a control circuit for controlling a supply of electric power to a discharge lamp, whereby the supply of power to the discharge lamp is controlled by the control circuit in response to a lowering of the DC input voltage when the lowering of the DC input voltage is detected, wherein
- power control is performed so that the supply of power to the discharge lamp is decreased by the control circuit as the ambient temperature rises even though the lowering of the DC input voltage remains unchanged.
A discharge-lamp lighting circuit comprising:
- a DC-DC converter circuit for boosting or lowering a DC input voltage from a DC power supply, a DC-AC converter circuit for converting an output voltage of the DC-DC converter circuit to an AC voltage, and a control circuit for controlling a supply of electric power to a discharge lamp, whereby the supply of power to the discharge lamp is controlled by the control circuit in response to a lowering of the DC input voltage when the fall of the DC input voltage to a threshold or lower is detected, wherein
- power control is performed so that when the DC input voltage falls to the threshold or lower, the supply of power to the discharge lamp is decreased by the control circuit as the lowering degree grows greater and as a time during which the DC input voltage remains at the threshold or lower grows longer.
Dependencies are inferred from the claim text.