The invention relates to linear lighting and to channels for linear lighting.
Linear lighting is a class of solid-state lighting in which light-emitting diode (LED) light engines are mounted on an elongate, narrow printed circuit board (PCB), spaced at some regular spacing or pitch. The PCB may be flexible or rigid. Connected to an appropriate power supply, linear lighting may serve as a luminaire in its own right, and is often used as a raw material in the construction of more complex luminaires.
It's become common to encapsulate linear lighting within a polymeric covering. This kind of encapsulation protects the linear lighting from the elements. In some cases, the encapsulation may have additional functions as well, such as diffusing the emitted light.
One issue with encapsulated linear lighting is connecting it to power. Typically, a strip of encapsulated linear lighting is connected to power by soldering conductors from a cable to solder pads defined on the PCB. For example, in FIG. 1 of U.S. Pat. No. 10,801,716, the contents of which are incorporated by reference herein in their entirety, a cable is shown entering the encapsulation of a strip of linear lighting at one end. Wires from the cable are soldered to solder pads on the PCB. As shown in the figure, a power cable usually extends at least a few millimeters into the encapsulation; this penetration distance ensures that the encapsulation will not leak around the cable, and provides some degree of strain relief to the cable.
There are several difficulties with this sort of cable penetration. First, it is usually desirable to make an encapsulated strip of linear lighting as small as possible in all dimensions. However, with the traditional arrangement, one must make the encapsulation, or at least a portion of it, as large as the power and data cable that extends into the encapsulation. This is especially cumbersome when the cable is large—and safety regulations may require a large, heavily-jacketed cable in many scenarios, including situations in which the encapsulated linear lighting is to be fully immersed in water.
Additionally, it is not always convenient for a cable to protrude from one end of an encapsulated strip of linear lighting. There are certain cases in which it would be of great benefit for a cable to be connected elsewhere on a strip of linear lighting. However, robust techniques for attaching a cable elsewhere have not been developed.
One aspect of the invention relates to a linear luminaire. The linear luminaire comprises a channel with a pair of generally vertical sidewalls connected together and spaced apart by a web, defining an upper compartment and a lower compartment. The web has one or more slots therein. At least one piece of encapsulated linear lighting is positioned in the upper compartment of the channel. The encapsulated linear lighting has an overmold that extends through one of the one or more slots in the web, into the lower compartment when the linear lighting is in the upper compartment. A cable extends out of the overmold and extends along the lower compartment in a direction parallel to a length of the linear lighting.
In some embodiments, a second piece of encapsulated linear lighting may be positioned in the upper compartment of the channel abutting an end of the first piece of linear lighting so as to create the appearance of a continuous line of light when the two pieces of encapsulated linear lighting are lit. The second piece of encapsulated linear lighting also extends through one of the one or more slots in the web. A cable extends out of that overmold and extends along the lower compartment as well. Thus, the lower compartment of the channel serves as a cableway, with the slots in the web allowing the overmolds and cables to extend into the lower compartment while the pieces of encapsulated linear lighting sit flat and flush in the upper compartments of the channel.
Another aspect of the invention relates to methods for creating a strip of encapsulated linear lighting with an overmolded cable. In these methods, a strip of linear lighting is laid in a channel. Electrical connections are made to solder pads on the strip of linear lighting, such that a cable extends out of the linear lighting. The channel is filled with a resin to create a covering or encapsulation. The cable is overmolded. In some embodiments, the channel may be filled in a first orientation, and the overmold may be created by placing the channel in a second orientation in a mold to create the overmold. Depending on the embodiment, the electrical connections may be made by through-hole mounting an electrical connector through aligned holes in the PCB and channel, connecting wires to the connector, and overmolding the connection. The overmold may be positioned below the main extent of the channel in some embodiments.
Other aspects, features, and advantages of the invention will be set forth in the description that follows.
The invention will be described with respect to the following drawing figures, in which like numerals represent like features throughout the description, and in which:
The PCB 12 and LED light engines 14 may be of any type. As used here, the term “LED light engines” refers to one or more LEDs in a package that includes all connections necessary to be mounted on a printed circuit board. Some LED light engines 14, in particular those intended to emit so-called “white” light, may be topped with a phosphor, a chemical mixture that absorbs the light emitted by the LEDs and re-emits a different spectrum of light wavelengths. In other cases, the LED light engines 14 may be RGB light engines, i.e., those that include red, green, and blue LEDs and can produce a range of colors by additive color mixing. The form of the LED light engines 14 may vary from embodiment to embodiment, they may be more or less numerous than illustrated in
The PCB 12 may be flexible or rigid. Flexible PCB is typically made with a material such as MYLAR® biaxially-oriented polyethylene terephthalate. Rigid PCB may be made of a metal, such as aluminum, a ceramic, or a composite material, such as FR4. Flexible PCB may be backed with a layer of pressure-sensitive adhesive, in which case it is commonly referred to in the industry as “tape light.”
In the illustration of
The covering 16 in its finished form is solid and completely encapsulates the PCB 12. However, the covering 16 is typically made in several steps with individual components. Generally speaking, the covering 16 is made according to the steps outlined in U.S. Pat. No. 10,801,716, which was incorporated by reference above. Typically, the PCB 12 is placed in a channel 22, e.g., by securing its pressure-sensitive adhesive layer to the bottom of the channel 22 and then filling the channel 22 with a resin. In order to fill the channel 22 with resin, the ends are dammed in some manner. In some embodiments, endcaps may be glued, fused, or otherwise permanently secured at the ends of the channel 22. However, in other embodiments, removable stoppers may be used to temporarily dam the ends of the channel 22. When the encapsulation process is complete, the channel 22 may or may not be easily distinguishable from the resin that fills it. In many cases, the channel 22 is made of a reflective white or white-ceramic resin, such that the channel 22 is distinguishable from the resin when the covering 16 is complete; however, the channel 22 may be made of the same type and color of resin that is used to fill it.
The PCB 12 usually has a two-layer construction, with the LED light engines 14 on the upper layer and a patterned conductive layer as the lower layer. PCB 12 for linear lighting is usually laid out in repeating blocks, divided by cut points. A repeating block is a complete lighting circuit; connected to power, it will light. The cut points are the points at which one repeating block may be cut or otherwise separated from another without damaging either repeating block. Cut points may be marked on the upper surface of the PCB 12, e.g., by screen printing, or they may be deduced using landmarks on the PCB 12. As shown, the PCB 12 includes sets of solder pads 19. Physically, the solder pads 19 are areas where the insulator of the upper layer of the PCB 12 is removed to expose the conductor on the lower layer. The solder pads 19 serve as electrical connection points, and while soldering is one way in which connections may be made to the solder pads 19, in some cases, solder pads 19 may also accept connections from electrical connectors. The number and position of the solder pads 19 may vary from embodiment to embodiment, depending on the number of inputs that the LED light engines 14 require in order to operate. In the illustrated embodiment, the LED light engines 14 are lined up in a row in the center of the PCB 12 while the solder pads 19 extend to either side of the LED light engines 14.
One unique feature of the illustrated encapsulated linear lighting 10 is the way in which it is connected to power. That is illustrated in more detail in the cross-sectional view of
As shown, the pins 30 make a 90° turn after exiting the covering 16 to extend parallel to the PCB 12. In this embodiment, the conductors 26 are soldered to the other ends of the pins 30. However, other connectors may use other arrangements, including terminal blocks for securing conductors 26.
This is not the only connection arrangement that can be used. For example, through-holes may be provided or formed in other areas of the PCB 12, and the conductors 26 and/or wires 24 may be routed through the through-holes and soldered to the solder pads 19 on the upper side of the PCB 12. In some cases, the conductors 26 and/or wires 24 may traverse some length of the PCB 12.
The advantage of the arrangement shown in
In the description above, the term “cable” is used to describe the structure that conveys power and/or signals into the encapsulated linear lighting 10. The term “cable” usually denotes one or more wires or other types of conductors with an outer jacketing. Some forms of cable may also include electromagnetic shielding or other features. While a cable 20 according to embodiments of the invention may have any or all of these features, the term “cable” in this description should be read broadly to include any types of conductors that provide power and/or signals. For example, the term “cable” should be read to include an unjacketed assemblage of wires.
There are several tasks involved in creating an overmold 18, and these are illustrated in
In some cases, conductors 26 from wires 24 may be inserted directly into the through-holes 32, 34 and soldered in place, such that a connector 28 is unnecessary and is thus omitted. If the conductors 26 are stranded wire, they may be tinned to assist with insertion. Direct connection of the conductors 26 to the PCB 12 has the advantage of using one fewer part in making the connection, although doing so may require cable management during the channel-filling process. On the other hand, the advantage of a connector 28 is that its pins 30 presumably have the correct dimensions to be inserted in the through-holes 32, 34, while the conductors 26 of the cable 20 may be of any thicknesses or other dimensions. Therefore, the use of a connector 28 may allow the use of thicker conductors 26 and wires of greater ampacity, irrespective of the dimensions necessary to connect to the PCB 12. A connector 28 may be particularly helpful, for example, when the encapsulated linear lighting 10 is intended to have a high ingress protection rating and may spend considerable amounts of time underwater or in other difficult environments. In these cases, the cable 20 may be required by applicable safety regulations to use heavy-gauge conductors 26 and to have particularly thick jacketing.
Method 100 continues with task 108, the manufacturing process proceeds much as normal, and the channel 22 is filled with resin. There is only one change in the typical process at this point: structures are used to support the channel 22 around the connector 28, which is protruding from the bottom of the channel 22. One way of doing this is shown in
In some cases, the two adjacent carriers 50, 52 may provide adequate support for the channel 22 as it fills. However, it is possible that without side support, the channel 22 may bulge outward as it fills. For that reason, it is possible to use carriers that provide side support but have an opening in the bottom.
In the illustrated embodiment, each carrier 150, 152 is designed to simultaneously carry and support up to six separate segments of channel 22 during the filling and curing process. Each carrier 150, 152 defines six slots 156 in which to do so. In this embodiment, the sidewalls 158 of the slots 156 have features, such as a protruding line 160, complementary to those of the channel 22.
The first carrier 150 is designed to accommodate the connector 28 and is thus different from the second carrier 152. Specifically, each slot 156 in the first carrier 150 has an opening 160 that goes through the bottom of the carrier 150. In the area around the opening 160, the slot 156 has sidewalls 158 but no bottom.
As with other instances in which a channel 22 is filled, it may proceed in several stages, and the channel 22 may be “dosed” with resin in several layers. For example, a thin layer of resin may be deposited around and over the LED light engines 14 and cured, and then a thicker layer or layers of resin may be deposited and cured. Alternatively, the channel 22 may be filled and cured with a single dosing of resin. The advantage of using several layers of resin is that it may be easier to eliminate air bubbles, although doing so generally takes more time.
Once the channel 22 is filled and cured, method 100 continues with task 109 and the cable 20 is attached to the connector 28. While the electrical connections between the connector 28 and the PCB 12 may be tested after task 106, the cable 20 is not usually attached prior to filling in task 108 because doing so might require a long length of cable 20 to be accommodated on the working bed of a machine that has limited space. While exceptions may be made, it is usually easier to attach the cable 20 to the connector 28 once the filling and curing operations are complete. Thus, in task 109, wires 24 and their conductors 26 are connected to the pins 30 of the connector 28. Typically, this would also be done by soldering, although crimps, press-fit arrangements, and other means of electrical and mechanical connection may be used. Because of the support offered by the overmold 18, the manner of connection may not need to support a significant amount of weight.
Method 100 continues with task 110. In task 110, the filled, cured channel 22 with connected wires 24 and cable 20 is placed in a mold for overmolding. As those of skill in the art will appreciate, the overmold 18 shown in
Although injection molding can be used to produce the overmold 18, the present inventors have found that the overmold 18 can advantageously be produced by the same low-pressure liquid resin techniques that are used to fill the channel 22 to create the covering 16. The present inventors have also discovered that if the overmold 18 is produced by the kind of low-pressure liquid resin techniques described above, it is advantageous if this is done in an accessible way.
It would be possible, for example, to place the channel 22 in a one-piece (i.e., open) or two-piece mold in the same orientation as shown in
Method 100 and
The ability to manage the entry and exit of power cables in encapsulated linear lighting 10 may allow for more flexibility in how linear lighting 10 can be used. Ultimately, creative placement of an overmold and thoughtful consideration of where and how a cable 20 should exit encapsulated linear lighting may help to overcome a number of practical limitations, including limitations on maximum length. All linear lighting has some limit to its length, whether that limit is electrical (e.g., the maximum length of linear lighting that can be effectively lit if supplied with power from a single point) or a functional limit on the maximum length of linear lighting that can be manufactured in a particular process. However, in applications of linear lighting, it is often desirable for linear lighting to span a length greater than the maximum length that it is possible to make any one strip of linear lighting. If issues of cable-exit are handled creatively, it may allow a designer to at least seemingly overcome some of these issues.
The effect of the structure shown in
Although
The overmold 18 shown in the figures lies below the main extent of the channel 22. However, that orientation may differ from embodiment to embodiment. An electrical connector or wires may enter a strip of encapsulated linear lighting from the top or a side, and an overmold may be formed along those aspects of the channel 22 as well. The location of the overmold and the manner in which a connector or conductors enter the covering 16 will depend on the overall application for the encapsulated linear lighting and where space exists for the overmold. The advantage of the channel 200 is that it creates space for the overmold 18 below the main extent of the encapsulated linear lighting 10.
While the invention has been described with respect to certain embodiments, the description is intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention, which is defined by the appended claims.
Number | Name | Date | Kind |
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10801716 | Lopez-Martinez et al. | Oct 2020 | B1 |
11168852 | Irons | Nov 2021 | B1 |
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20150369459 | Huang | Dec 2015 | A1 |
20170138578 | Pearson | May 2017 | A1 |
20170292664 | Pearson | Oct 2017 | A1 |
20180031189 | Pearson | Feb 2018 | A1 |
20190003666 | Pearson | Jan 2019 | A1 |
20200041103 | Germain | Feb 2020 | A1 |
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