| 摘要 |
<p>The invention relates to a circuit and a method for efficiently supplying lighting apparatuses with LEDs directly from the public system of alternating voltage of 230 V. According to the invention, the circuit consists of a module comprising N segments of M serially-mounted LEDs, a constant current source being mounted in series with the LED segments connected directly to the output of a rectifying bridge and a switch being mounted in parallel on each segment, except the segment proximal to the current source, the current source being either fixed or AM- or FM-modulated according to a deterministic or aleatory modulation law. The method, as claimed by the invention, consists in that the circuit absorbs from the supply system a rectangular current pulse proportioned depending on the desired efficiency or the desired crest factor which is subsequently modulated; when the voltage increase at the circuit terminals exceeds the calculated threshold voltages, the switches successively introduce, in series with the current source and with the already present segments, one additional segment at a time, said additional segment consisting of M LEDs which are, in their turn, serially connected and which take over the voltage drop from the current source; when the voltage decreases, at the circuit terminals, below the same voltage thresholds, the switches shortcircuit a segment of M serially connected LEDs which is thereby eliminated from the circuit, thus the value of the current passing through the segments which remain in the circuit increasing up to the limit of the current absorbed by the current source.</p> |
