AC-powered LED light engine

摘要

AC LED light engines powered directly from the AC power line contain circuitry of resistors, capacitors, diodes and transistors which enables a single string LEDs connected to series to efficiently produce light with a relatively low level of flicker as perceived by the human eye. The LEDs are driven by a current which is alternately capacitively-limited and resistively-limited. Capacitively-limited pulses of current are interposed between resistively-limited pulses of current so that the resulting output current ripple is at frequencies of 240 Hz or above which the human eye cannot perceive. The combination of resistively-limited current and capacitively-limited current results in a current drain from the power line which is generally sinusoidal and can have a power factor in excess of 0.70.

主权项

1. A driverless light emitting diode (LED) light engine for providing illumination from an AC voltage source, the driverless LED light engine comprising:
a plurality of individual LEDs connected in series as a single string of LEDs, defined as comprising a plurality of LED substrings; resistance means disposed along a signal path including the AC voltage source and the single string of LEDs; and at least two separate bias capacitors connected between the AC voltage and one or more LED substrings, the at least two bias capacitors supplying capacitively-limited current so that at some points in time during an AC voltage cycle, at least one LED substring receives capacitively-limited current, and at other points in time during said AC voltage cycle said at least one LED substring receives resistively-limited current.