AC to DC LED illumination devices, systems and methods
Illumination devices ( 10 ), systems and methods that convert an alternating current (AC) supply ( 14 ) to a direct current (DC) for powering a plurality of light emitting diodes (LEDs) are disclosed. An illumination device ( 10 ) comprises a full wave rectifier ( 12 ) for converting the AC supply into a direct current (DC). A current limiting diode (CLD) module ( 16 ), comprising at least two CLDs coupled in parallel, is coupled in series to an output of the full wave rectifier and a light emitting diode (LED) module ( 18 ) comprising a plurality of LEDs is coupled in series between an output of the CLD module ( 16 ) and the full wave rectifier ( 12 ).
1. An illumination device comprising:
a full wave rectifier for converting an alternating current (AC) supply into a direct current (DC);
a current limiting diode (CLD) module coupled in series to an output of the full wave rectifier, the CLD module comprising at least two CLDs coupled in parallel;
a light emitting diode (LED) module coupled in series between an output of the CLD module and the full wave rectifier, the LED module comprising a plurality of LEDs; and
wherein a pulsed (DC) forward current having a truncated waveform is supplied to the LED module.
2. The illumination device of claim 1 , wherein the full wave rectifier is a bridge rectifier comprising a single component.
3. The illumination device of claim 1 , wherein the full wave rectifier comprises four rectifier diodes in a bridge configuration.
4. The illumination device of claim 1 , wherein the LED module comprises at least thirty LEDs in series.
5. The illumination device of claim 1 , wherein the LED module comprises one or more LED blocks, each LED block comprising two or more LEDs in parallel.
6. The illumination device of claim 5 , wherein each LED block comprises two or more LEDs in series.
7. The illumination device of claim 1 , wherein the CLD module comprises at least one switch in series with at least one of the CLDs.
8. The illumination device of claim 7 , wherein the at least one switch is a mechanical switch or an electronic switch.
9. The illumination device of claim 1 , wherein the sum of a voltage drop across the CLD module and the LED module is at least 90% of the AC supply voltage.
10. The illumination device of claim 1 , wherein a number of LEDs in the LED module and a number of CLDs in the CLD module are selected to provide a pulsed forward current having pulses comprising flat peaks for at least 10% of the duration of the power cycle.
11. The illumination device of claim 1 , further comprising a positive temperature coefficient (PTC) resettable fuse coupled in series between the AC supply and an input of the full wave rectifier.
12. The illumination device of claim 1 , comprising at least two LED modules and at least two CLD modules, each LED module coupled in series to a respective CLD module.
13. The illumination device of claim 12 , wherein each LED module comprises LEDs of a single color.
14. The illumination device of claim 1 , further comprising:
a connector for connecting the illumination device to the AC supply;
a housing coupled to the connector; and
a substrate coupled to the connector within the housing, the plurality of LEDs mounted on the substrate.
15. The illumination device of claim 14 , wherein the at least two CLDs and the full wave rectifier are mounted to the substrate.
16. The illumination device of claim 14 , wherein the at least two CLDs and the full wave rectifier are coupled to the connector and are external to the housing.
17. The illumination device of claim 16 , further comprising at least one switch in series with at least one of the CLDs, wherein the at least one switch and the CLDs are external to the housing.
18. The illumination device of claim 17 , comprising:
at least two LED modules and at least two CLD modules, each LED module coupled in series to a respective CLD module, each LED module comprising LEDs of a single color; and
a switch coupled in series with each CLD module.
19. The illumination device of claim 17 , wherein the at least one switch is operated via a string or cord coupled to the connector.
20. The illumination device of claim 1 , further comprising:
a digital switching circuit coupled in series with at least one of the CLDs;
a wireless transmission circuit coupled to the digital switching circuit; and
a wireless receiver coupled to the wireless transmission circuit.
21. The illumination device of claim 20 , wherein one or more of the following are provided within a housing of the illumination device: the full wave rectifier; the CLD module; the LED module; the digital switching circuit; the wireless transmission circuit; the wireless receiver; a substrate.
22. The illumination device of claim 20 , comprising at least two LED modules and at least two CLD modules, each LED module coupled in series to a respective CLD module, each LED module comprising LEDs of a single color.
23. An illumination system comprising at least two of the illumination devices of claim 14 , wherein each illumination device comprises at least two connectors to electrically couple one of the illumination devices to at least one other illumination device.
24. The illumination system of claim 23 , wherein each of the at least two connectors is in the form of a female socket for receiving a male connector of a cable.
25. The illumination system of claim 23 , wherein one of the connectors of a first illumination device is in the form of a female socket for receiving a male plug of another illumination device and another of the connectors of the first illumination device is in the form of a male plug for insertion in a female socket of another illumination device.
26. A method of powering an illumination device including:
converting an alternating current (AC) supply into a direct current (DC) with a full wave rectifier;
passing the DC into:
a current limiting diode (CLD) module coupled in series to an output of the full wave rectifier, the CLD module comprising at least two CLDs coupled in parallel; and
supplying a pulsed forward current having a truncated waveform to a light emitting diode (LED) module coupled in series between an output of the CLD module and the full wave rectifier, the LED module comprising a plurality of LEDs.
27. The method of claim 26 , including controlling illumination provided by the LED module with at least one switch in series with at least one of the CLDs in the CLD module.
28. The method of claim 26 , including selecting a number of LEDs in the LED module and a number of CLDs in the CLD module to provide a pulsed forward current, the pulsed forward current having pulses comprising flat peaks for at least 10% of the duration of the current cycle.