Modular light-string system having independently addressable lighting elements
Apparatus and associated methods relate to modular series-connectable LED light strings having an input connector and an output connector for electrically communicating power and a control signal, an input control signal being actively level-shifted to a level suitable to a first lighting element of the LED light string. In an illustrative embodiment, the LED light string may have a plurality of series connected lighting elements that generate a series of intermediate supply voltage levels. In some embodiments, the active level shifter may bias the input control signal between an DC voltage level applied to a positive supply pin of the first lighting element and the intermediate supply voltage level generated at the connection of a negative supply pin of the first lighting element and the positive supply pin of the second lighting element. In some embodiments, active level-shifting may advantageously restore the proper bias for a series connected light string.
1. A modular light-string system comprising:
a pluggable input connector configured to receive operating power and an input light-string control signal;
a series-connected plurality of independently controllable lighting elements generating a series of distinct intermediate supply-voltage levels each shared by a negative supply pin of a first lighting element of an adjacent pair of lighting elements and a positive supply pin of a second element of the adjacent pair of lighting elements, the second lighting element of each adjacent pair receiving the control signal from the first lighting element of the adjacent pair;
wherein each of said lighting elements has a control module and a plurality of independently controllable Light Emitting Diodes (LEDs), the control module generating an illumination signal for each of the plurality of LEDs in response to the received control signal, wherein the received control signal comprises a plurality of independent control subsignals that correspond to each of the plurality of independently controllable lighting elements, respectively;
a level shifter comprising an optocoupler and configured to actively translate the control signal received by the input connector from a first voltage range to a second voltage range, wherein the second voltage range is between a DC voltage supplied to the positive supply pin of the first lighting element of the series-connected plurality of independently controllable lighting elements and the intermediate supply voltage between the first and second lighting elements of the series-connected plurality of independently controllable lighting elements, and wherein the output of the optocoupler is biased between an electrical connection to the received operating power and an electrical connection to the positive supply pin of the first lighting element; and,
a pluggable output connector configured to provide the received operating power and the control signal output by a last lighting element in the series-connected plurality of independently controllable lighting elements to another modular light-string system, when connected,
wherein each of the series-connected plurality of independently controllable lighting element has a single level shifter.
2. The modular light-string system of claim 1 , wherein the optocoupler comprises an input terminal and an output terminal.
3. The modular light-string system of claim 2 , wherein the output terminal of the optocoupler is electrically coupled to a first terminal of a resistor.
4. The modular light-string system of claim 3 , further comprising a transistor having an input terminal and an output terminal, the input terminal electrically coupled to a second terminal of the resistor, the output terminal configured to generate a translated control signal corresponding the input control signal received by the input connector.
5. The modular light-string system of claim 1 , further comprising a first supply voltage, wherein the first supply voltage comprises an AC voltage.
6. The modular light-string system of claim 5 , further comprising an AC/DC converter that converts the first supply voltage to the DC voltage supplied to the positive supply pin of the first lighting element of the series-connected plurality of independently controllable lighting elements.
7. The modular light-string system of claim 6 , wherein the DC voltage is greater than fifty volts.
8. The modular light-string system of claim 1 , further comprising a first supply voltage, wherein the first supply voltage comprises a DC voltage.
9. The modular light-string system of claim 1 , further comprising a second supply voltage, wherein the second supply voltage is substantially a circuit ground reference potential.