| 摘要 |
PROBLEM TO BE SOLVED: To provide an LED drive circuit enabled to restrain adverse effects due to variations in forward voltages of LEDs contained in a plurality of LED blocks, in case the plurality of LED blocks are changed over and driven by switching.SOLUTION: The LED drive circuit (3) is provided with a first switch portion (23) carrying out an ON/OFF operation of currents flowing from positive outputs to negative outputs through a first LED group (21) connected to a rectifier (12), a first circuit (20) equipped with a constant current circuit (24) making a current flowing in the first LED group constant and a first voltage detecting portion (22), and a second circuit (40) equipped with a second LED group (41) connected to the rectifier. The first voltage detecting portion detects voltage fall by the constant current circuit connected with the first LED group, and controls the first switch portion to change over between a current route from the first LED group to another of the next step and a current route from the first LED group to a negative output. |
