Patent ID: 9345087
Filing Date: 2016-05-17
CPC Classification: H05B

Claim Text:
1. An ac-powered LED light engine, coupled between a rectifier and a plurality of extrinsic LED sub-arrays, comprising: a plurality of normally closed bypass switches, each connected in parallel with a corresponding LED sub-array except for a topmost or a bottommost LED sub-array and shuttling between three switch states: ON, REGULATION, and OFF; a normally closed current regulator coupled to the normally closed bypass switches and used to regulate a highest LED current level near a peak of an extrinsic mains voltage; a plurality of switch controllers each coupled to a corresponding normally closed bypass switch as a feedback network and taking control of the three switch states according to a corresponding current sense signal, wherein each of the switch controllers is a BJT-based gate-driving circuit, a shunt regulator-based gate-driving circuit, or a Photo Coupler-based gate-driving circuit for controlling the corresponding normally closed bypass switch in the three switch states; and a plurality of current-sensing resistors connected in series with the extrinsic LED sub-arrays, wherein the number of the current-sensing resistors is the same as the number of the normally closed bypass switches, and when one of the normally closed bypass switches works as a regulating bypass switch in the REGULATION state, any normally closed bypass switch on one side of the regulating bypass switch stays in the OFF state, and any normally closed bypass switch on the other side of the regulating bypass switch stays in the ON state.