| 摘要 |
<p>An LED array switching apparatus comprises, on a single PCB substrate: a plurality of LED arrays D1 to Dn connected in series, each LED array having a forward voltage; an AC voltage supply coupled to the plurality of LED arrays; and a plurality of constant current sources G1 to Gn, coupled to outputs of LED arrays D1 to Dn, respectively, each of the constant current sources being switchable between a current regulating state and an open state such that as the voltage of the AC voltage supply increases, LED arrays are switched on and lit to form a higher forward voltage LED string, and as the voltage of the AC voltage supply decreases, LED arrays are switched off and removed from the LED string starting with the most recently lit LED array.</p> |
