Light emitting diodes (“LEDs”) are employed as a basic lighting structure in a variety of forms, such as outdoor signage and decorative lighting. LED-based light strings have been used in channel lettering systems, architectural border tube applications, under cabinet lighting applications and for general illumination. A known spoolable LED light string arranges the LEDs in parallel circuitry. This parallel arrangement requires a very low voltage output power supply (Vout approximately 2.0 to 4.5 VDC) and a large amount of drive current capability. The large currents that must be delivered severely limits the distance that the power supply can be spaced from the LED strip as well as the length of the LED strip that can be driven by the power supply.
Known LED string lights also use parallel/series combinations of LEDs. These known systems require that the LEDs mount to a printed circuit board as well as some sort of current limiting device. These known systems require the printed circuit board to be environmentally isolated, which is expensive. Furthermore, the printed circuit board based systems are also difficult to spool, to mount and to cut to length in addition to requiring the expense of the printed circuit board itself.
Other known LED light strings employ a plurality of LEDs wired in a series/parallel block that are run directly off AC power. These known systems require complicated designs to account for the alternating current.
The present LED light engine contemplates an improved apparatus and method that overcomes the above-mentioned limitations and others.
An LED light engine includes a flexible electrical cable and a plurality of LEDs. The flexible electrical cable includes first, second and third electrical conductors and an electrically insulating covering for the electrical conductors. The conductors are arranged substantially parallel with one another having an insulating material therebetween. A first LED including a first lead electrically connects to the first electrical conductor and a second lead of the first LED electrically connects to the second conductor. A second LED includes a first lead electrically connected to the second electrical conductor and a second lead electrically connected to the third electrical conductor. A third LED includes first and second leads electrically connected to the second conductor. The third LED is interposed between the first LED and the second LED.
A method of manufacturing an LED light engine is disclosed. The method includes insulating first, second and third conductive elements to form an insulated conductor. The insulated conductor includes insulating material interposed between the conductive elements. The method further includes mechanically securing a plurality of LEDs spaced along the insulated conductor. The method further includes electrically contacting a first lead of a first LED of the plurality of LEDs to the first conductive element and a second lead of the first LED to the second conductive element. The method further includes electrically contacting a first lead and a second lead of a second LED of the plurality of LEDs to the second conductive element. The method further includes electrically separating the second conductive element between the first lead and the second lead of the second LED. The method further includes electrically contacting a first lead of a third LED of the plurality of LEDs to the second conductive element and a second lead of the third LED to the third conductive element. The second LED is interposed between the first LED and the third LED.
A light string includes a plurality of LEDs connected to one another in parallel, a predetermined number of LEDs electrically connected to one another in series, and conditioning electronics in electrical communication with the plurality of LEDs. The predetermined number of LEDs is electrically interposed between adjacent LEDs that are electrically connected to one another in parallel. The conditioning electronics convert AC power to DC power for driving the LEDs.
With reference to
The light strip, in a preferred embodiment, is powered by AC power. In one embodiment, conditioning electronics 20 (
The insulated flexible electric cord 12 includes a first conductor 22, a second conductor 24 and a third conductor 26. Each of the conductors 22, 24 and 26 is preferably sized to be about 18 gauge. Additionally, each conductor is preferably stranded and includes a plurality of strands (e.g., seven strands). With a current running through the flexible electrical cord 12, the first conductor 22 can be referred to as the positive (+) conductor, the third conductor can be referred to as the negative (−) conductor, and the second conductor 24 can be referred to as the series conductor. Each of the conductors is situated generally parallel to one another and an insulating material 28 (e.g., rubber, PVC, silicone and/or EPDM), is situated between the conductors.
The electrical cord 12 can include an alignment mechanism to facilitate alignment of the socket housing 14 on the electrical cord. In a preferred embodiment, the alignment mechanism is two grooves 30, which have a V-shaped configuration, into which a portion of the socket housing 14 can be received. Alignment of the socket housing 14 with the grooves 30 aligns the internal components located in the socket housing, which will be described in more detail below, with the electrical conductors 22, 24 and 26 in the cord 12 to promote a good electrical connection. In alternative embodiments, the alignment mechanism can include a line drawn or made on the cord, or any conventional indicia to facilitate location of the socket housing 14 on the electrical cord.
The socket housing 14 attaches to the insulated flexible electrical cord 12. In a preferred embodiment, the socket housing is a molded body of a plastic or other suitable electrically insulating material. With reference to
The prongs 42 include insulation-piercing members that are arranged in a substantially fixed manner in slots or openings (not shown) in the socket body 32. The prongs 42 are formed from sheet metal or another suitably electrically conductive material. With reference to
With continued reference to
The snapping connection of the socket body 32 and the socket cover 34 about the cable 12 effectuates both a mechanical connection of the LED 16 to the cable 12 as well as a simultaneous electrical connection of the positive and negative (anode and cathode) terminals of the LED 12 via the prongs 42 to the conductors 22, 24 or 26 that supply electrical power. With reference back to
The upwardly extending wall 72 includes a knurl 82 positioned above the electrical cord 12 when the socket body 32 attaches to the socket cover 34. The knurl 82 engages an opening 84 located on the socket body 32. The knurl and opening provide a selective engagement between the socket body 32 and the socket cover 34; however, the socket body and the socket cover can secure to one another in any conventional manner. The wall 72 also includes alignment members 86 that are received in the grooves 30 of the electrical cord 12. The alignment members 86 further align the socket housing 14 in a direction generally perpendicular to the length of the electrical cord 12. With reference back to
In an alternative embodiment, the wall 72 can also include an insulation barrier (not shown) that is aligned to fit between the prongs 42 and separate the series conductor 24 between the prongs 42 when the socket body 32 attaches to the socket cover 34. The insulation barrier can comprise a dielectric material that can puncture through the insulating material 28 of the electrical cord 12 and also cut through the series conductor 24 thus electrically separating the series conductor between two adjacent prongs 42. In an alternative embodiment, the series conductor 24 can be cut by a feature integral to the socket body 32 and this feature can also electrically separate the series conductor 24 between two adjacent prongs 42. In yet another alternative embodiment, a secondary component can be inserted into the socket housing 14, i.e., through an opening (not shown) in the socket cover 34.
A mounting portion 94 also attaches to the socket housing 14. The mounting portion in the light engine depicted in
The mechanical connection between the socket housing 14 and the electrical cord 12 facilitates placement of the light engine 10 in a channel letter 100. As seen in
The electrical connection between the components of the light engine 10 need not include auxiliary electrical components, such as resistors and the like, and need not include soldering. Preferably, the conductors 22, 24 and 26, the prongs 42 and the LED leads 48 are formed from substantially similar metals to reduce galvanic corrosion at the electrically contacting interfaces, or are coated with a conductive coating that reduces galvanic corrosion at the interfaces.
The orientation of the prongs 42 inside the socket body 32 is dependent upon the location of the socket housing 14 along the electrical cord 12. As best shown in
With reference to
A light engine 10 that has a parallel and series electrical configuration has been described. The conditioning electronics 20 allow DC power to run the LEDs 14, allowing for a less complicated design. Furthermore, due to the electrical configuration, current limiting resistors are not required in the light engine. Also, by connecting some of the LEDs in series, the amount of current required to drive the light engine can be lessened.
The light engine has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. As just one example, the light engine was described with particular reference to LEDs; however, as indicated above, the light source can be any conventional light source, including incandescent bulbs. It is intended that the light engine be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.