Patent Application
20190049077
In general, the invention relates to flexible power distribution systems, and more particularly, to flexible power distribution systems for powering lighting fixtures.
Over the last decade, lighting based on light-emitting diodes (LEDs) has become dominant in the lighting industry and is widely used in both residential and commercial installations. LED-based lighting has a number of advantages compared with legacy incandescent and fluorescent lighting, including high efficiency and low power draw, relatively low operating temperatures, and, with some models, selectable color and a wide variety of available color temperatures.
For most commercial and residential applications, two major types of LED-based lighting are used: bulb-type lamps and linear lighting. Bulb-type lamps are intended as direct replacements for incandescent light bulbs, typically have a shape similar to the type of bulb they are intended to replace, and are usually constructed to produce roughly the same light output as the bulbs they are intended to replace. Linear lighting is somewhat different—it usually includes a number of LEDs arranged at a regular spacing or pitch along a printed circuit board (PCB). That PCB may be rigid, made, for example, of FR4 composite, or it may be flexible, made, for example, of Mylar. In either case, the PCB usually has the form of a thin strip, although other shapes and sizes are possible.
One of the major advantages of linear lighting is its versatility. Alone, it can serve as accent lighting or task lighting, often in locations where it would be difficult to install traditional lighting fixtures. Placed in an appropriate extrusion and covered with a diffuser, it can serve as primary room lighting, replacing legacy fluorescent fixtures in offices. Properly electrically insulated and encapsulated, it can be used even in outdoor and wet locations.
The versatility of LED lighting in general, and linear lighting in particular, creates a problem: supplying power. Most household and commercial power is high-voltage, alternating current (AC) power. Most LED lighting fixtures operate using low-voltage direct current (DC) power. (While the definitions of “low voltage” and “high voltage” depend on the authority one consults, for purposes of this description, voltages over about 50V will be considered to be high voltage.) To convert from high-voltage AC to low-voltage DC, a driver is usually used. Drivers are typically large, bulky components whose size increases with the amount of power they are designed to supply, and finding space for them in any particular installation can be difficult.
In complex installations, providing power can be even more difficult. In some situations, linear lighting may be installed along multiple surfaces, and some independent strips of linear lighting may be far from the driver that is intended to power them. U.S. Pat. No. 9,404,645, which is incorporated by reference in its entirety, deals with this problem in the context of gondola shelving units. That patent describes a set of at least semi-rigid printed circuit boards (PCBs) with surface-mounted connectors.
One aspect of the invention relates to a flexible power connector strip. The flexible power connector strip comprises an elongate, flexible printed circuit board. The printed circuit board defines a pair of connectors, typically on a metallization layer within the printed circuit board. A plurality of connectors are mounted on the flexible printed circuit board. Each of the plurality of connectors is electrically connected to the pair of conductors.
Typically, the power connector strip comprises a plurality of sections of flexible printed circuit board that are soldered together at overlap joints to form the entire length of the power connector strip. In this way, the power connector strip itself may be of arbitrary length. Each of the sections of printed circuit board may have more solder contacts than are necessary for electrical connection such that some of the contacts can be used for alignment purposes. The solder contacts may be concealed. In most embodiments, the power connector strip will have an attachment mechanism, such as adhesive or magnets, on its reverse in order to attach it to a surface.
The connectors may be any type of connector that is mountable on the printed circuit board, either by surface mounting or by another process. The connectors may be male or female. While in most embodiments, each power connector will accept a complementary connector, in some embodiments, the connectors may be terminal blocks or other structures that will accept either bare wire leads or another type of dissimilar connecting structure. While in many embodiments, each of the independent functional units will be identical to the others, such that any connector can be an input connector and any connector can be an output connector, in other embodiments, the functional units may be different, with some specialized for input and others specialized for output. Functional units or other portions of the power connector strip may be connected by thinned, undulating portions to allow the power connector strip to flex in multiple planes.
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 invention, and in which:
The PCB 12 itself is typically thin and elongate (i.e., much longer than it is wide). For example, PCB 12 widths in the range of 10-20 mm may be particularly suitable, depending on the nature of the connectors 14, 16 that are to be mounted. For example, in one embodiment, the PCB 12 may be 14 mm wide. The PCB 12 is also flexible, made, for example, of a material such as Mylar. Of course, Mylar is not the only material from which the PCB 12 may be made—in sufficiently thin section, many materials possess the kind of flexibility that is useful in the power connector strip 10, including thin sections of FR4 (i.e., glass fiber composite), aluminum, polyimide, silicon, gold, carbon nanotubes, and any number of plastics. The PCB 12 may be manufactured using any suitable technique.
The power connector strip 10 may be of any length, ranging from a few centimeters to several meters or more. The only potential limitation on length is the inherent electrical resistance of the PCB 12 and its metallization layers, which causes a voltage drop over extended lengths. If only a single power source is connected at one end of the PCB 12, at some length, the voltage will have dropped to a voltage that is no longer usable. If the power connector strip 10 needs to be run to particularly long lengths (e.g., greater than a few meters), the problem of ohmic voltage drop can be addressed by increasing the amount of conductive material in the strip 10, either by widening the strip 10 to include more conductive material, or by adding additional metalization layers and vias to connect those layers.
The PCB 12 itself is constructed in repeating blocks that are connected together to create a power connector strip 10 of arbitrary length.
Each repeating block 18 is divided into units 19. Each unit 19 is a complete electrical circuit unto itself, including several connectors 14, 16 and the circuitry needed to support the connectors 14, 16. In the illustrated embodiment, each unit 19 includes one right-facing connector 14 and one left-facing connector 16. Depending on the application, power connector strips 10 may have connectors facing in other directions or extending along other planes as well. Although the repeating block 18 of the illustrated embodiment includes multiple units 19, each repeating block 18 may include only a single unit 19.
Because each unit 19 is a complete electrical circuit, each unit 19 is separable from the others. In the illustrated embodiment, cut points 20 are marked on the PCB 12 by screen printing or another appropriate technique. The PCB 12 can be physically cut by a knife, scissors, or another appropriate implement to separate the individual units 19. The physical length of one unit 19 is the minimum functional length that the power connector strip 10 can be. As will be described below in more detail, that minimum functional length may vary from one embodiment to another depending on the type and size of connectors 14, 16 that are used, the pitch at which the connectors 14, 16 are spaced, and a number of other factors.
In addition to the cut-points 20 that separate adjacent units 19, each repeating block 18 has a set of conductive contacts 22 that can be soldered or adhered to contacts 22 from other repeating blocks 18 to create a long, continuous power connector strip 10 of arbitrary length. There are four separate contacts 22 in the illustrated embodiment, although there may be more or fewer in other embodiments. These contacts 22 are used to connect adjacent repeating blocks 18 into a single power connector strip 10.
As those of ordinary skill in the art will realize, if the power connector strip 10 carries only power, there need only be two contacts 22—one for power and one for ground or neutral. The presence of four contacts 22 in the illustrated embodiment helps to ensure proper alignment between adjacent repeating blocks 18. Preferably, where a connection is made, the contacts 22 on the upper of the two repeating blocks 18 are covered, so that the joint is not visible from the top on casual inspection. In some cases, this may be used to discourage soldering to the power connector strip 10.
The connectors 14, 16 themselves may be any type of connectors that can be mounted on or connected to the PCB 12. In the illustrated embodiment, the connectors 14, 16 are female surface-mount connectors, but in various embodiments, they may be either male or female. While the connectors 14, 16 are shown on only one side of the PCB 12, in some embodiments, they could be installed on both sides of the PCB 12.
As can be appreciated from
The particular pitch at which the connectors 14, 16 are set, the length of the repeating blocks 18, and the interval at which cut points 20 are set may vary widely from embodiment to embodiment. A lesser connector pitch and shorter intervals between cut points 20 may be convenient for end installers, because the resulting power connector strip 10 can be cut more closely to desired lengths (e.g., it can be cut at 1-inch intervals, instead of 4-inches, etc.). Of course, decreasing the length of the repeating blocks 18 may increase the overall cost of the power connector strip 10 commensurately. That said, the only physical lower limit to the length of each repeating block 18 is the size of the connectors 14, 16.
Depending on the embodiment, the power connector strip 10 may have adhesive, magnetic strip, or other such elements on its reverse, in order to facilitate its installation on a surface. Alternatively, in some embodiments, the PCB 12 may be designed and manufactured with openings in it in order to secure nails, screws, and other such fasteners.
With the power connector strip 10 of
In most embodiments, the power connector strip 10 will carry low voltage, and the connectors 14, 16 will have two separate contacts, for power and ground. However, in some embodiments, the power connector strip 10 and the connectors 14, 16 may have additional contacts for signals. For example, in another embodiment, a power connector strip may carry a 0-10V dimming signal for dimming and control purposes. In that case, additional conductors would be provided on the PCB, and the connectors would be chosen appropriately. It should be understood, however, that the power connector strip 10 is not necessarily limited to low voltage. If the power connector strip 10 carries high voltage (e.g., typical household or commercial voltage), it may be provided with additional layers of insulation, as required by applicable electrical regulatory code.
One particular advantage of power connector strip 10 according to embodiments of the invention is that the flexibility of the power connector strip 10 allows it to be stored and shipped more easily than comparable rigid strips. As one example,
In the embodiments of
In power connector strip 150, the two units 154 are separated by a thinned, undulating strip of PCB material 160. The undulating strip 160 allows the power connector strip 150 to flex in plane, as illustrated in the top plan view of
Typically, to make power connector strip 150, undulating conductive traces (for power and neutral or ground) would be defined in the metalization layer of a PCB, and then the undulating shape of the undulating strip 160 would be defined and cut around those conductive traces by a conventional cutting method, e.g., die cutting or laser cutting. The embodiment of
Because of the reduced size of the undulating strip 160, it may have reduced ampacity relative to comparable conductive traces on a linear power conductor strip 10, 100. If additional current-carrying capacity is desirable or necessary, the PCB can be made with additional metalization layers to carry current, using vias to connect vertically-adjacent layers.
The embodiments shown in
The primary visible difference between power connector strip 200 and the low-voltage power connector strips 10, 100, 150 described above is an electrically insulative external covering, generally indicated at 202. The covering 202 is usually polymeric and flexible, and may be either transparent or opaque, depending on the embodiment. Suitable materials for the covering 202 include, e.g., PVC and EPDM polymers, although any electrically insulative material may be used, whether natural or synthetic. The particular materials that are used will depend on the voltage that power connector strip 200 carries, as well as the desired heat tolerance and flame ratings. Those heat tolerances and flame ratings may be dictated by electrical code or other regulatory standards.
Within the covering 202, the arrangement of power connector strip 200 is generally similar to its low-voltage counterparts, although the connectors and conductors would generally be rated for higher voltages and greater current-carrying capacities. In the illustrated embodiment, the covering 202 is opaque, although it may be transparent or translucent in other embodiments. Power connector strip 200 maintains the convention of having some connectors 204 face one direction and other connectors 206 face another direction; thus, in the view of
Power connector strip 200 would typically maintain the same kind of architecture as its lower-voltage variants: repeating blocks divided into individual units, with each unit including one or more connectors. In power connector strip 200 of
As with the embodiments described above, the units 208 of power connector strip 200 are separable, independent circuits that can be physically cut or divided from the other units 208. For the sake of convenience, on an opaque covering 202, the cut points 210 may be physically marked on the exterior of the covering 202. Alternatively, the portion of the covering 202 around a cut point 210 may be transparent to reveal cut-point markings on the encapsulated PCB 212.
Cutting a high-voltage power connector strip 200 may require additional steps. For example, after separating units 208 at their cut points, exposed ends of the units 208 may be sealed with electrically insulative material. This may involve adhering endcaps over the ends, potting the ends with an insulative compound, or applying some other insulator so that the resulting shortened power connector strip 200 is fully insulated. Depending on local safety regulations, cutting operations may be performed in the field by any installer, they may be restricted to properly trained personnel, or they may be restricted such that they are only done in the factory or by other trained and authorized entities.
In the description above, the electrical circuits involved are relatively simple. Contact traces on a flexible printed circuit board take the place of stranded copper wires or other, similar conductors. However, the units 19, 154, 208 may include more advanced circuitry and circuit components for some applications.
One advantage of simple-circuit power connector strips, like the power connector strip 10 described above, is that any connector 14, 16 can serve as the input and any connector 14, 16 can serve as the output. While adding additional circuit components to the individual units 19, 154, 208 may adapt them for special applications, it may also affect the ability of any connector 14, 16 to serve as either input or output. Still, the trade-off in functionality may be acceptable or even necessary in some embodiments.
As more circuit components are added, the individual units may not be identical to each other. Instead, some units may be specialized. For example, a power connector strip may have a specialized input unit and a number of output units in the same strip.
The characteristics of the input unit 404 will vary with the particular application and the type of power that the power connector strip 400 is designed to accept. Specialized input units 404 may be particularly helpful, for example, where the incoming power is noisy or has unwanted voltage or current spikes. In these cases, it may be necessary or desirable to filter the power before it is output to the load. A specialized input unit 404 may also be helpful if the incoming power is AC power, but the load requires either DC power or a modified AC power with, e.g. a higher frequency.
In
Beyond the input connectors 14, 16 in the input unit 404, a fuse 408 and polarity-protecting diode 410 are provided, as was described above with respect to
The filter 412 may be any type of filter, including a high-pass filter, a low-pass filter, or a band-pass filter. The cut-off frequency or frequencies for the filter 412 will differ from application to application. If AC power is to be converted to DC, or if a higher frequency is required, the input block 404 may also include a rectifier or other such components. Thus, the term “filter,” as used here, should be read broadly to encompass any components that alter the incoming power signal.
With respect to AC-to-DC conversion, U.S. Pat. No. 10,028,345, which is incorporated by reference in its entirety, discloses a number of different circuits for converting AC power to DC power on a flexible PCB, and for filtering the resulting power. Those circuits, or similar ones, may be used in embodiments of the invention. U.S. Pat. No. 10,028,345 discloses how to rectify and filter high-voltage AC power using a minimal number of components placed on a flexible PCB. The circuits typically comprise a rectifier and a simple passive capacitive filter, although some of the disclosed circuits do use a first-stage transistor-based capacitance multiplier and second-stage passive capacitive filters. However, the circuits of the '345 patent do not include a transformer to reduce the input voltage. Overall, the characteristics of the power-modifying components in the input unit 404 will vary with the embodiment, the application for which the power connector strip 400 is used, and the characteristics of the power that is required. The component 412 shown in
The output units 406 are much like the units 19, 154, 208 of other embodiments: they have a number of connectors 14, 16. While the repeating block 402 of
If more output units 406 are needed without input units 404, the unneeded input units 404 could be severed from power connector strip 400 and the resulting separate strips of output units 406 could be connected together with cables using their connectors 14, 16. Alternatively, if the conductive contacts 22 of the repeating blocks 402 are accessible, repeating blocks 402 of the power connector strip 400 may be joined by connectors. For example, the connectors disclosed in U.S. Pat. 10,024,526, the contents of which are incorporated by reference in their entirety, may be suitable for connecting repeating blocks 402 using their conductive contacts 22.
As those of skill in the art will note, the input unit 404 of
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.
This application claims priority to U.S. Provisional Patent Application No. 62/544,653, filed Aug. 11, 2017. The contents of that application are incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62544653 | Aug 2017 | US |
