AU2011223984A1 - LED string light engine - Google Patents

Abstract

C:\NRPodb\DCOPLW647819_I.DOC8/5/20 I A string light engine includes a support holding plurality of LEDs, a plurality of 1OC connectors, and an insulated flexible conductor. Each IDC connector is in electrical 5 communication with at least one of the plurality of LEDs and is operatively mechanically connected to at least one of the plurality of LEDs. The IDC connectors attach to the conductor. An overmolded housing at least substantially surrounds the support and a portion of the conductor. o

Description

Australian Patents Act 1990 - Regulation 3.2A ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title "LED STRING LIGHT ENGINE" The following statement is a full description of this invention, including the best method of performing it known to us:- C:\NRPob\DCC\PLW\3647819_I.DOC-I&85I/2011 LED STRING LIGHT ENGINE BACKGROUND OF THE INVENTION [0001] LED string light engines are used for many applications, for example as accent 5 lighting, architectural lighting, and the like. The profile, i.e. the height and width, of known flexible LED light string engines is wide enough such that it can be difficult to install these known light string engines in certain environments. [0002] LED string light engines are also used in channel letters. A typically channel letter has a five inch can depth, which is the distance between the rear wall of the channel 10 letter and the translucent cover. To illuminate the channel letter, a string LED light engine attaches to the rear wall and directs light towards the translucent cover. To optimize efficiency, typically the LEDs are spaced from one another as far as possible before any dark spots are noticeable on the translucent cover. To achieve no dark spots, the LEDs are spaced close enough to one another so that the light beam pattern generated by each 15 LED overlaps an adjacent LED as the light beam pattern contacts the translucent cover. Accordingly, the translucent cover is illuminated in a generally even manner having no bright spots nor any dark spots. [0003] Channel letters are also manufactured having a shallower can depth, such as about two inches. Typically, the smaller channel letters also have a smaller channel width. 20 If the same light string engine that was used to illuminate the smaller channel letters is used to illuminate the larger channel letters, then bright spots may be noticeable because the beam pattern overlap is not as great where the beam pattern contacts the translucent cover. 25 SUMMARY [0003A] According to the present invention, there is provided a thin, low-profile string light engine comprising: a plurality of LEDs; a plurality of IDC connectors, each IDC connector being in electrical communication with at least one of the plurality of LEDs and operatively mechanically connected to at least one of the plurality of LEDs; an insulated 30 flexible conductor including at least two wires, the IDC connectors including a terminal inserted into the conductor, the conductor including a first portion where the IDC connector is inserted into the conductor where the at least two wires reside generally in a first plane and a second portion spaced along a length of the conductor from the first portion, in the second portion the at least two wires reside in a second plane that is at an 35 angle other than 1800 as compared to the first plane.

C:\NRPortbl\DCCPLW\16478I9_.DOC-1 /05/2011 [0004] In one embodiment, a light string engine includes a conductor, a first support, a second support, a first IDC connector, a second IDC connector, a first LED, a second LED, a first overmolded housing, and a second overmolded housing. In this embodiment, the conductor is a flexible insulated electrical conductor. The first support and the second 5 support each include a dielectric layer and circuitry. 1A The second support Is spaced from the first support along a length of the conductor. The first IDC connector and the second IDC connector each extend away from the first support and the second support, respectively. Each IDC connector is in electrical communication with the circuitry of the respective support. Each IDC connector includes a terminal that is inserted into the conductor to provide an electrical connection between the conductor and the respective circuitry. The first LED mounts to the first support and Is in electrical communication with the circuitry of the first support. The second LED mounts to the second support and is in electrical communication with the circuitry of the second support. The first overmolded housing at least substantially surrounds the first support and a portion. of the conductor adjacent the first support. The second overmolded housing at least substantially surrounds the second support and a portion of the conductor adjacent the second support. [00051 An example of a method of manufacturing a string light engine Includes the following steps: connecting a first LED assembly to an Insulated conductor; connecting a second LED assembly to the insulated conductor; overmolding a first housing over at least a portion of the first LED assembly and a portion of the insulated conductor, and overmolding a second housing over at least a portion of the second LED assembly and a portion of the Insulated conductor. Each LED. assembly includes a support an LED mounted to the respective support and an IDC connector operatively fastened to the respective support. [00063 An embodiment of a thin, low-profile string light engine Includes a plurality of LEDs, a plurality of IDC connectors, and an insulated flexible conductor. Each I6C connector Is in electrical communication with at least one of the plurality of LEDs and is operatively mechanically connected to at least one of the plurality of LEDs. The conductor includes at least two wires. The IDC connectors are Inserted Into the conductor. The conductor Includes a first portion where the IDC connector is inserted into the conductor where the at least two wires reside generally in a first plane. The conductor also includes a second portion spaced along the length of the conductor from the first portion. The at least two wires reside in a second plane in the second porton. The second plane is at an angle other than 180* as compared to the first plane. 2 C:NRPotbl\DCCPLW64719.1.DOC-I&5/2011 Embodiments of the invention will now be described in greater detail by way of example with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS 5 [0007] FIGURE 1 is a perspective view of a string light engine; [0008] FIGURE 2 is an exploded perspective view of components of the string light engine of FIGURE 1; [0009] FIGURE 3 is an assembled view of the string light engine of FIGURE 1 prior to overmolding a housing on the string light engine; 10 [0010] FIGURE 4 is a perspective view of an assembly of the string light engine of FIGURE 1; [0011] FIGURE 5 is a bottom view of the assembly of FIGURE 4; [0012] FIGURE 6 is an end view of the assembly of FIGURE 4; and [0013] FIGURE 7 is a plan view of a power conductor of the string light engine of 15 FIGURE 1. DETAILED DESCRIPTION [0014] With reference to FIGURE 1, a flexible LED string light engine 10 generally includes a flexible electrical power conductor 12 and LED modules 14 attached along the 20 length of the conductor. The light engine 10 is flexible so that it can be bent and shaped into many desirable configurations so that it can fit into, for example a channel letter, and can be used in many different environments. FIGURE 1 depicts only a portion of the light engine which can extend along a much greater distance than that depicted in FIGURE 1. The string light engine 10 can be manufactured to have the length of many feet or meters 25 long. In one embodiment, the light sources, which will be described in more detail below, are spaced relatively close to one another to provide a desired beam overlap pattern. The string light engine 10 is configured to easily bend in a manner that will be described in more detail below. [0015] The power conductor 12 in the depicted embodiment includes three conductor 30 wires: a positive (+) conductor wire 20, a negative (-) conductor wire 22 and a series conductor wire 24. Accordingly, the LED modules 14 can be arranged in a series/parallel arrangement along the power conductor 12. A fewer or greater number of conductor wires can be provided. The wires in the depicted embodiment 3 are 22 gage, however other size wires can also be used. The conductor wires 20, 22 and 24 are surrounded by an Insulating material 26. [0016] In the depicted embodiment, the power conductor 12 Is continuous between adjacent LED modules 14 such that the entire power conductor 121s not cut or otherwise terminated to facilitate a mechanical or electrical connection between the LED module and the power conductor. A continuous power conductor 12 quickens the manufacturing of the light engine 10, as compared to light engines that terminate the power conductor when connecting it to an LED module. [0017] The wires 20, 22 and 24 of the power conductor can be described as residing generally. in a plane at different locations along the length of the power conductor. With reference to FIGURE 2, the power conductors reside In a first or primary bending plane 28 adjacent each LED module. As seen in FIGURE 2, the power conductor 12 includes a twist 30, which in the depicted embodiment isa one quarter twist, such that the power conductor resides in. a second or connection plane 32 where the LED module attaches to the power conductor 12. In an alternative embodiment, the twist 30 may not be a one-quarter twist; rather, the twist may be smaller where the two planes 28 and 32 may only be at an angle other than 1800 from one another. The configuration of the power conductor 12 allows the LED light string 10 to easily bend In a direction that Is at an angle to the primary bending plane 28. This is because the force(s) required to bend the power conductor 12 in the primary bending plane 28 is small because the width of the power conductor in the primary bending plane 28 is equal to the diameter of a conductor wire and the surrounding Insulation as compared to the width of the power conductor in the connection plane 32 which equals the entire -width of the power conductor 12. The twist 28 allows for a low-profile LED module to attach to the power conductor 12. In other words, the height and width of each LEO oidule. 14 can be smaller, as compared to known light string engines. [0018]' The LED modules 14 attach to the power conductor 12 spaced along the length of the power conductor. In the embodiment depicted and as seen in FIGURE 3, each LED .module 14 Includes an assembly 38 that attaches to the power conductor 12. With reference to FIGURE 4, the assembly 38 includes at least one LED 40 (two LEDs are shown), which in the depicted embodiment Is a surface 4 mounted LED, placed on a support 42, which in the depicted embodiment is a printed circuit board ("PCB"). In the depicted embodiment, the printed circuit boards 42 that mount to the power conductor 12 have similar dimensions (see FIGURE 3); however, the circuitry located on each PCB and the components that mountto each PCB can be different. Solder pads 44 are disposed on an upper dielectric surface of each PCB 42. Leads 46 for each LED 40 electrically connect to the solder pads 44. [0019] An LED driver 48 mounts on the upper surface of some of the printed circuit boards 42. The LED driver 48 is in electrical communication with the LEDs 40. A resistor 52 also mounts on the upper surface of some of the printed circuit boards 42. the resistor 52 is also in communication with the LEDs 40. In the depicted embodiment some PCBs 42 are provided without resistors and LED drivers and some PCBs are not (see FIGURES 2 and 3). Accordingly, the circuitry located on each PCB 42 interconnecting the LEDs 40 to the power conductor 12 Is different. In the depicted embodiment, two different wiring configurations are provided for the PCBs: one wiring configuration fbr the PCB having the resistor and LED driver and one wiring configurationfbr the PCB having no resistor or LED driver. [0020] in an alternative embodiment, the support upon which the LED is mounted can be a flex circtor other similar support. Furthermore, the LEDs that mount to the support, either the flex circuit or the PCB, can include chip on board LEDs and through-hole LEDs. Also, other electronics can mount to the support including a device that can regulate the voltage as a functioW.':fthe LED temperature or the ambient temperature. Furthermore, these electronics, including the resistor, the LED driver, and any temperature compensating electronics can be located on a component that is in electrical communication with the LEDs but niot located on the support. [0021] With reference back to the depicted embodiment as seen in FIGURE 4, an IDC connector 58 depends from a lower surface of the support 42. In the depicted embodiment, the IDQ connector58 Is mechanically fastened to the support 42,.which operatively connects the IDC connector to the LEDs 40. Even though the IDC connector Is depicted as directly attaching to the support 42, other elements or 5 components can be Interposed between the two. When the IDC connector 58 attaches to the power conductor 12, the support 42 resides In a plane generally parallel with the connection plane 32 (FIGURE 2). [0022] With reference to FIGURE 5, In the depicted embodiment the IDC connector 58 includes a plurality of IDC terminals. A first series IDC terminal 60 depends from a lower surface of the support 42 and is in electrical communication with the LEDs 40 through circuitry (not shown) printed on the upper dielectric layer of the support 42. A second IDC terminal 62 is spaced from the first series IDC terminal 60 and also depends from the lower surface of the support 42. The second series IDC terminal 62 is also in communication with the LEDs 40. The first and second series [DC terminals 60 and 62 pierce the insulation 26 surrounding the series wire 24 to provide an electrical connection between the LEDs 40 and the series wire. The IDC connector 58 in this embodiment also Includes an insulative barrier 64 disposed between the first series terminal 60 and the second series terminal 62. [0023] A negative IDC terminal 66 also depends from a lower surface of the support 42. Similar to the first series IDC terminal 60 and the second series IDC terminal 62, the negative IDC terminal 66 is In electrical communication with the tEDs 40 via circuitry disposed on an upper dielectjic surface of the support 42. The negative IDC terminal 66 displaces insulation surrounding the negative wire 22 to provide an electrical connection between the LEDs 40 and the negative wire. A positive IDC terminal 68 also depends from a lower s6ce'of the support 42. The positive lDC terminal 68 Is In electrical communication with the LEDs 40 via circuitry provided on an upper surface of the support 42. The positive IDC terminal 68 displaces insulation 26 surrounding the positive wire 20 to provide for an electrical connection between the LEDs 40 and the positive wire.' In the depicted embodiment, each IDC connector 58 has the same electrical configuration. The support 42 to which the connector 58 attaches has a different electrical configuration based on the electrical components mounted on the support. For example, the DC terminals for one connector can electrically communicate with the resistor 52 and/or the LED driver 48 that Is located on some of the supports 42. 6 [00241 With reference back to FIGURE 4, the IDC connector58 also includes an IDC connector housing 70 that Includes dielectric side walls 72, which in the depicted embodiment are made of plastic, that depend from opposite sides of the support 42 In.the same general direction as the IDC terminals. As seen in FIGURES 5 and 6, the IDC terminals 60, 62, 66 and 68 are disposed between the sidewalls 72. With reference to FIGURE 6, the sidewalls 72 are spaced from one another to define a channel 74 configured to snugly receive the power conductor 12. A power conductor seat 76 depends from a lower surface of the support 42 In the same general direction as the IDC connectors and the sidewalls 72. The seat 76 includes three curved recesses, one recess for each wire of the power conductor 12. A tab 78 extends from each sidewall 72 to facilitate attaching the IDC connector housing 70 to an IDCcover80 (FIGURE 2-). Each sidewal 72 also includes vertical ridges 82 formed on opposite sides of each tab 78. The vertical ridges 82 also facilitate attachment of the IDC connector housing 70 to the DC cover 80. Stops 84 extend outwardly from each sidewall 72 at an upper end of each vertical ridge 82. -The stops 84 extend further from each sidewall 72 than the vertical ridges 82. [0025] As seen in FIGURE 2, the IDC cover 80 Includes a base wall 86 defining an upwardly extending power conductor seat 88 that includes curved portions for receiving the separate wires of the power conductor 12. The curved portions of the power conductor seat 88 align with the curved portions of the power conductor seat 74 of the IDC connector housing 70. Sidewalls 90 extend upwardly from opposite - sides of the base wall 86 of the IDC cover 80. Each. sidewall 90 includes an opening 92 configured to receIve the tab 78 exteniding Outwardly from each sidewalk 72 of the IDC-connector housing 70. Internal vertical notches 94 are formed on an Inner surface of each sIdewall 90 to receive the vertical ridges 82 formed on the sliewalls 72 of the IDC connector housing'10. Ndt6hes 96 are.f6rmed in' each sidewall 90 of the IDC. cover 80 to receive the stops 84 formed on the IDC connector housing 70. [00261 The support 42 attaches to the power conductor 12 by pressing the support into the power conductor 12 such that the IDC terminals 60,62, 66 and 68 displace the insulation 26 around each wire of the power conductor. The cover 80 is then pressed toward the support 42 such that the tabs 78 lock Into the notches 92 7 to secure each support 42 to the power conductor 12. The tabs 78 are ramped to facilitate this connection. When attached to the power conductor 12, the support resides in a plane that is -generally parallel to the connection plane 32. [0027] 'With reference back to FIGURE 1, an overmolded housing 110 at least substantially surrounds each support 42 and a portion of the conductor 12 adjacent each support. The overmolded housing includes openings 112 through which an upper surface of each LED 40, which Is typically covered by a lens, extends. Accordingly, in the depicted embodiment the overmolded housing 110 does not completely encapsulate the support 42 to an LEDs 40; however, if desired the housing could cover the LEDs 40, especially If the housing were to be made of a light-transmissive material. Each overmold housing 110 also includes notches 114 formed in the overmold housing for supporting the support 42 during overmolding, which will be described In more detail below. [0028] in the depicted embodiment, a strain relief member 116 Is disposed between adjacent overmolded housings 110 and surrounds the power conductor 12. The strain relief member 116 includes a plurality of loops 118 that surround the power conductor 12 and are separated by openings 122. The strain relief members are configured to limit any forces on the conductor 12 that are external the overmolded housing 110 from transferring to the portion of the power conductor 12 disposed inside the overmolded housing. This is to limit any stresses on the IDC connector 58 so that good mechanical and electrical connection is maintained between the support 42 and the IDC connector. [0029] A mounting element 124 connects to the power conductor 12 extending from the- strain relief member 116. In the depicted embodiment, the mounting element 124 comprises a loop 126 defining an opening 128 dimensioned to receive a fastener (not shown). The mounting element 124 can take ilfaemaWe configurations to allow the light engine 10 to attach to a mounting surface. Furthermore, the light engine 10 can mount to a mounting surface via an'adhesive that attaches to either the powerconductor 12 or the overmold housing 110, as well as in other conventional manners. [0030] To assemble the light engine 10 the series conductor wire 24 of the power conductor 12 is punched out to form slots 140 (FIGURE 7) at predetermined 8 locations along the power conductor 12. The power conductor 12 is twisted (see FIGURE 2). Each support 42 and the accompanying IDC connector housing 70 and IDC terminals 60, 62, 66 and 68 are disposed such.that the connector insulation barrier member 64 (FIGURES 5 and 6) of each IDC connector housing Is disposed inside the slot 140 and the IDC terminals contact the respective conductor wires of the power conductor 12. The IDC cover 80 is then fit over the IDC connector housing 70 so that the power conductor 12 is fully seated in each of the power conductor seats 74 and 86. The overmolded housing 110 is then formed over the support 42 and the power conductor 12 adjacent the support [0031] With reference back to FIGURE 1, In one method two adjacent housings 110 and the interconnecting strain relief member 116 along with the mounting element 124 are formed from as an integral unit. Two adjacent supports 42 can be inserted into a mold and a thermoplastic, for example a thermoplastic elastomer, Is Injected Into the mold to form the overmolded housing 110, Instead of an elastomer, i.e. a material that is flexible after solidifying, the overmolded housing can also be a rigid plastl, or other suitable material. When using the injection molding thermoplastic process as described above, the-thermoplastic is typically Injected at pressures between about 5-35 kpsi and at temperatures In the range of about 140-500'C, and typically between about 140-230*C. The thermoplastic then cools and Is removed from the mold. Alternatively, the overmolded housing can be formed Using a liquid Injection molding process and/or a casting process. The power conductor 12 and the assembly 38 can also be run through an extruder so that the overmolded housing is extruded over the assembly and the power conductor. [0032] In other embodiments the entire light engine 10, 6r a substantial portion thereof, can be overmoided. Tlhe thermoplastic used to make thd overmdcided housing can be opaque. As discussed above, the upper surface of each LED 42 is not covered; however, in an alternative embodiment the upper surface of each LED can be covered where the overmolded housing Is formed of a light-transmissive material. The overmolded housing 110 provides a further mechanical connection between the support 42 and the power conductor 12 as well as acting as a barrier from the elements for the components disposed inside the overmolded housing. 9 .

The overmolded housing 110 also provides for thermal management of the LED modules 14. The overmolded housing 110 increases the surface area of the LED module, as compared to having no housing, which has been found to lower the thermal resistance to the ambient, as compared to having no housing. [0033] A string light engine and a method for manufacturing the string light: engine has been described with reference to certain embodiments. Modifications and- alterations will occur to those upon reading and understanding the detailed description. The invention is not limited to only those embodiments described above; rather, the invention is defined by the appended claims and the equivalents thereof. 10

Claims (6)

1. A thin, low-profile string light engine comprising: a plurality of LEDs; 5 a plurality of IDC connectors, each IDC connector being in electrical communication with at least one of the plurality of LEDs and operatively mechanically connected to at least one of the plurality of LEDs; an insulated flexible conductor including at least two wires, the IDC connectors including a terminal inserted into the conductor, the conductor including a first portion 10 where the IDC connector is inserted into the conductor where the at least two wires reside generally in a first plane and a second portion spaced along a length of the conductor from the first portion, in the second portion the at least two wires reside in a second plane that is at an angle other than 1800 as compared to the first plane. 15

2. The light engine of claim 1, wherein the conductor includes a twist disposed between the first portion and the second portion.

3. The light engine of claim 1, further comprising a plurality of supports, each support being connected to at least one of the IDC connectors and at least one of the LEDs. 20

4. The light engine of claim 1, further comprising an overmolded housing at least partially encapsulating at least one of the plurality of LEDs, at least one of the plurality of IDC connectors and at least a portion of the flexible conductor. 25

5. The light engine of claim 4, wherein the overmolded housing comprises material having heat conductive properties that are greater than air.

6. A string light engine substantially as hereinbefore described with reference to the accompanying drawings. 11