| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To be able to make dimming brightness of an LED lamp and to light an LED lamp stably even if a phase control type dimmer with a triac is used as a power supply circuit. <P>SOLUTION: In an LED lighting circuit, full wave rectification of AC voltage supplied from the power supply circuit is carried out by a rectifying circuit 5. In a region where an input power voltage is low and a current does not flow in the LED 4, a constant current flows in a bypass circuit 6. In a region where an input voltage is high and a current flows in the LED 4, a current control circuit 8 detects the current flowing in the LED 4 and reduces the current flowing in the bypass circuit 6 to enable to improve power supply efficiency. And, since a filter circuit 7 absorbs a pulse voltage and makes it smooth even if the pulse voltage is superposed on the input voltage, the LED 4 does not suffer from discontinuous lighting. Namely, actuation of the phase control type dimmer does not become unstable even if the phase control type dimmer with a triac is used as the power supply circuit because the current in the lighting circuit 3 flows over a whole range of the output. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
