Patent Publication Number: US-2018031190-A1

Title: Scalable direct line voltage led luminaire tape

Description:
BACKGROUND 
     Technical Field 
     The present invention relates to light fixtures, and more particularly to light emitting diode (LED) fixtures configured in a tape, which can run off alternating current and provide a configurable length. 
     Description of the Related Art 
     Traditional light emitting diode (LED) luminaires are typically powered by either internal or external drivers (power supplies) which convert alternating current (AC) line voltage to direct current (DC) voltage. These power supplies are costly, inefficient, bulky, power limited and typically have a mean time before failure (MTBF) of about 50,000 hours. Wattage of the power supply defines a maximum lumen output of the luminaire. A form factor of the power supply defines a minimum size and shape of the luminaire. 
     SUMMARY 
     A lighting device includes a junction box and a power cord coupled to the junction box. A tape is connected to the junction box and is electrically coupled to the power cord. The tape includes light emitting diodes (LEDs) disposed in sections. Each section includes a repeating light engine block with the LEDs and a circuit repeat joint such that a dimension of the tape can be scaled by cutting the tape at a circuit repeat joint. 
     Another lighting device includes a junction box and an alternating current (AC) power cord coupled to the junction box. A flexible tape is connected to the junction box and is electrically coupled to the power cord. The tape includes a plurality of sections, each section including a repeating light engine block with a micro power supply, a circuit repeat joint and a plurality of light emitting diodes (LEDs), the tape having a customizable dimension that can be scaled by cutting the tape at a circuit repeat joint. An AC bus is disposed in the tape and is common to all sections to provide a single direct line power source feed to all the LEDs in the tape. 
     A method for configuring a lighting device includes providing a lighting device including a junction box, a power cord coupled to the junction box and a tape connected to the junction box and electrically coupled to the power cord, the tape including a plurality of light emitting diodes (LEDs) disposed in sections, each section including a repeating light engine block with the LEDs and a circuit repeat joint; and cutting the tape at a circuit repeat joint to scale a dimension of the tape. 
     These and other features and advantages will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The disclosure will provide details in the following description of preferred embodiments with reference to the following figures wherein: 
         FIG. 1  is perspective view of a lighting device showing a power cord and a light emitting diode (LED) strip connected to a junction box in accordance with one embodiment; 
         FIG. 2  is a cross-sectional view of the LED strip showing a casing, LED module and wireways in accordance with one embodiment; 
         FIG. 3  is a top view of the lighting device with a cover removed from the junction box in accordance with one embodiment; 
         FIG. 4  is a magnified top view of the lighting device with the cover removed from the junction box showing the internal components of the junction box in greater detail in accordance with one embodiment; 
         FIG. 5  is a schematic diagram of LED circuitry showing repeating light engine blocks with the LEDs and a circuit repeat joint to scale a dimension of the tape by cutting the tape at a circuit repeat joint in accordance with one embodiment; and 
         FIG. 6  is a block/flow diagram showing a method for customizing LED tape in accordance with the present principles. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In accordance with the present principles, systems, devices and methods are disclosed for a scalable luminaire device that overcomes the limitations of conventional devices. In one embodiment, the luminaire device includes a tape having LEDs disposed therein. The LEDs may be formed in any configuration and may employ one or more colors. The tape can be cut to size. The tape connects to a low profile end junction box having a largest dimension about a same size as the tape. An AC cord exits the junction box and can be plugged into any standard wall outlet or hardwired to an electrical box, etc. 
     A scalable LED luminaire in accordance with the present principles breaks down the power supply into micro power supplies which are linked together through a common AC bus. The micro power supplies are preferably cascaded in parallel. This provides greater reliability and flexibility than conventional designs by repeating the luminaire light engine block along a length of the luminaire. Luminaires from inches to hundreds of feet can be realized in accordance with the present embodiments. The wattage and associated lumen output can scale from fractions of a watt to thousands of watts by cutting the luminaire to a desired length at the circuit repeat joints. By incorporating an internal AC bus a single feed can be employed to drive extremely long lengths of fixtures before another feed is needed. This feature reduces installation labor and drives installation cost to a minimal level when compared to conventional driver powered luminaires. 
     The luminaire in accordance with the present principles provides a flexible lighting system that promotes layout design flexibility, junction box termination and no driver to hide. This permits easy integration in architectural spaces by an installer. The luminaire may include multiple mounting options and applications, including an extrusion design, cove, ambiance, task lighting, etc. The flexible light engine enables the creation of decorative patterns and is dimensionally manageable. In one embodiment, 4 inches (or smaller) cut lengths are permitted to provide run length flexibility. In one embodiment, run lengths of 150′ or greater can be achieved from one voltage feed. The luminaire is also configured to permit digital dimming. 
     It is to be understood that the present invention will be described in terms of a given illustrative structure or architecture having illustrative circuit layouts; however, other architectures, structures, components and process features and steps may be varied within the scope of the present invention. 
     It will also be understood that when an element or component is referred to as being “on” or “over” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “directly over” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     Reference in the specification to “one embodiment” or “an embodiment” of the present principles, as well as other variations thereof, means that a particular feature, structure, characteristic, and so forth described in connection with the embodiment is included in at least one embodiment of the present principles. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment”, as well any other variations, appearing in various places throughout the specification are not necessarily all referring to the same embodiment. 
     It is to be appreciated that the use of any of the following “/”, “and/or”, and “at least one of”, for example, in the cases of “A/B”, “A and/or B” and “at least one of A and B”, is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of both options (A and B). As a further example, in the cases of “A, B, and/or C” and “at least one of A, B, and C”, such phrasing is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of the third listed option (C) only, or the selection of the first and the second listed options (A and B) only, or the selection of the first and third listed options (A and C) only, or the selection of the second and third listed options (B and C) only, or the selection of all three options (A and B and C). This may be extended, as readily apparent by one of ordinary skill in this and related arts, for as many items listed. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element&#39;s or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the FIGS. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the FIGS. For example, if the device in the FIGS. is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may be interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the scope of the present concept. 
     Referring now to the drawings in which like numerals represent the same or similar elements and initially to  FIG. 1 , a lighting device  10  is shown in accordance with one illustrative embodiment. The lighting device  10  may provide a luminaire structure in the form of a light emitting diode (LED tape or strip  16 . The lighting device  10  includes an AC power cord  12  with a plug  15  configured to fit into any standard power outlet. The cord  12  connects to a junction box  14 . The cord  12  may include a bend limiter or include a stress relief portion  18  at an interface with the junction box  14 . The junction box  14  is configured to have a low-profile so that the junction box  14  does not impede placement and mounting of the device  10 . 
     The lighting strip or strips  16  are connected to the junction box  14  and powered using the AC power cord  12 . The power preferably includes a direct line voltage. The lighting strip  16  may include a linear array of light emitting diodes (LEDs)  20 . The lighting strip  16  is configurable such that portions of the lighting strip  16  can be removed by cutting to provide a tailored length of the lighting strip  16  for effect lighting or other applications. In other embodiment, the lighting strip  16  is configured to permit removable portions to be as low as 4 inch sections. In another embodiment, removable portions include a multiple of 4 inch sections. In other embodiments, the section(s) may include other lengths or combinations of lengths. The LEDs  20  may be spaced apart in accordance with a design application. In one illustrative embodiment, the LEDs are spaced apart from between about ½ inches to about 2 inches. Other spacings are also contemplated. 
     The LEDs  20  may include any color and may include different sizes and intensities as per the design of the lighting strip  16  and application. In useful embodiments, the LEDs  20  may include lighting effects, such as blinking, sequential lighting, altered intensities, etc. An optional dimmer circuit  52  includes a slide for dimming the device  10 . The end of the LED strip or tape  16  may include an end cap (not shown) to cover end portions of the tape  16  after it has been fabricated or after it has been cut. 
     Referring to  FIG. 2 , a cross-sectional view of the lighting strip  16  is illustratively shown in accordance with one embodiment. The lighting strip  16  includes an LED module  26 . The LED module  26  includes a flexible substrate, which may include a thermoplastic material, such as polyethylene, polyvinyl chloride, etc. LED circuitry is silk screened or deposited and etched onto the LED module  26 . The LEDs  20  are mounted on or through the LED module  26  and soldered, riveted or otherwise electrically connected to the LED module  26  and the LED circuitry. The LED circuitry is connected to power wires disposed in wireways  24  formed on opposing sides of the LED module  26 . The wireways  24  are electrically connected to the LED circuitry on the LED module  26 . The lighting strip  16  includes a connection to the wireways  25  at least once within each removable section. For example, if the removable section size is 4 inches, the tape section  40  includes at least one connection to each wireway  24  within that removable section  40 . 
     The LED module  26 , the LEDs  20 , and the wireways  24  are disposed within a casing  28 . The casing  28  may include an extruded plastic strip or tube. In other embodiments, the casing includes a flexibly cured or molded material. In still other embodiments, the casing  28  may be applied using a curable or thermal material that is applied to pot or encapsulate the components to form the casings  28 . The casing  28  may be transparent or colored. The casing  28  is preferably flexible to permit bending over a round surface or to be rolled up in a packaged state. 
     The casing  28  may include an optically clear material and include features (geometry) to disburse light at an angle of up to about 145 degrees. This can be achieved using geometrical shapes of the casing  28  or directing the LEDs  20 . Other light angles are also contemplated. In one embodiment, an extruded encapsulation jacket ( 28 ) provides encapsulation for a light engine. The casing  28  may include a 5 VA flame barrier that also acts as a voltage isolation barrier incorporated for safety. A composite thermal plastic may be employed for the casing  28 , which provides thermal dissipation through clear PVC material. F-1 rated materials for UV may be employed to eliminate discoloration and possible cracking and brittleness of the casing  28  over time. The casing  28  may include an extruded plastic jacket profile that provides numerous light distributions. 
     Referring to  FIG. 3 , a top view of the device  10  is shown with a cover removed from the junction box  14 . A cover is removed from the junction box  14  to reveal structures and components therein. A detail  28  is depicted in  FIG. 4  to show the internal portions of the junction box  14  in greater detail. 
     Referring to  FIG. 4  with continued reference to  FIG. 3 , the junction box  14  may include a split-half or clam shell housing  33  with a cover (not shown) removed for illustrative purposes. Housing  33  of the junction box  14  may include a molded plastic material. The junction box  14  receives the relief portion  18  of the AC cord  12 . The relief portion  18  may include flanges and/or torque stops  35  to prevent rotation and/or pullout of the cord  12  and relief portion  18  from the junction box  14  after being installed. The flanges and/or torque stops  35  fit within slot details  37  in the junction box  14 . Safer operation is achieved by employing a mechanically fastened cord with tooled strain relief  18  (connector) to prevent a shock hazard. 
     The relief portion  18  further includes a connector that connects AC wires in the cord  12  to pins  30  in the LED strip  16 . The pins  30  travel along the LED strip  16  in the wireways  24  of  FIG. 2 . In addition, ribs  32  are provided in the junction box  14  to grip the LED strip  16 . The cover (not shown) includes similar features to the open junction box  14  including ribs ( 32 ), slot detail  37  and a portion to receive the relief portion  18 . 
     During assembly, the junction box  14  is closed and secured using screws, snap together parts, rivets or other connecting devices. The ribs on the cover and the ribs  32  in the housing  33  are clamped down and grip the LED strip or tape  16 . The cover and the housing  33  secure the LED strip  16  within the junction box  14 . A sealant, such as an ultraviolet (UV) sealant compound, may be employed to coat the LED strip  16  and relief portion  18  to provide a water seal for the electrical components. 
     In one embodiment, a UV stabilized thermal plastic encapsulation jacket (thermoplastic polyurethane (TPU) or polyvinyl chloride ((PVC)) may be employed over the AC electrical parts (e.g.,  15 ,  16 ) in the junction box  14 . 
     Referring to  FIG. 5 , a schematic diagram shows LED circuitry  50 . The AC connector  15  receives line voltage and applied the voltage to an AC bus  34 . Incoming line voltage is tapped from internal AC. The circuit is stepped and repeated along the length of the luminaire (lighting device  10 ) utilizing, in one embodiment, high voltage LEDs  20  which greatly reduces the LED string length providing extremely small circuit repeat lengths. 
     The AC bus  34  is segmented into sections  40 . Each section  40  is connected to a plurality of LEDs  20  and a repeating light engine block  44  associated with that section  40 . In one embodiment, each section  40  includes a 4 inch length and includes six LEDs  20 . The sections  40  may include other lengths and other numbers of LEDs  20 . 
     The LED circuitry  50  includes a plurality of micro power supplies  36 , which are linked together through a common AC bus  34 . The micro power supplies  36  are preferably cascaded in parallel. This provides greater reliability and flexibility than conventional designs by repeating the luminaire light engine block along a length of the LED strip  16 . The sections  40  include circuit repeat joints  42  where the wattage and associated lumen output can scale from fractions of a watt to thousands of watts by cutting the luminaire to a desired length at the circuit repeat joints  42 . In one embodiment, the output of the tape  16  may include 5.5 W per foot and 500 lumens per foot at 4000K/80 CRI (color rendering index). Other temperature and colors are also contemplated (e.g., 2700K, 300K, 3500K, 4000K, etc., RGB, RGBW settings, high CRI (90+), etc.). 
     By incorporating an internal AC bus  34 , a single feed can be employed to drive extremely long lengths of fixtures before another feed is needed. This feature reduces installation labor and drives installation cost to a minimal level when compared to conventional driver powered luminaires. 
     The micro power supplies  36  connected to the AC bus  34  provide an AC to DC converter  39 . The AC voltage is locally rectified and converted to DC voltage by the AC to DC converter  39 , which includes a step down transformer  41  (e.g., 120 VAC to 5-20 VDC) and a rectifying circuit  43 . The rectifying circuit may include one or more diodes. In one embodiment, a rectifying bridge may be employed. A fuse may also be employed to protect the LEDs  20 . 
     Each segment  40  includes its own power supply  36  with A to D converter  39 , its own LEDs  20  and its own current regulator  38 . The string of LEDs  20  is current limited by the current regulator  38  which acts as a current limit switch. The A to D converter  39  provides rectification of the AC signal and transforms the higher AC voltage magnitude to a lower DC voltage suitable for powering the LEDs  20 . The current regulator  38  is connected at an end of a chain of LEDs  20  to reduce and control the current flow through the LEDs  20 . The LEDs  20  are connected in series or series parallel within each segment  40 . The number of LEDs  20  is determined in accordance with a forward DC voltage. 
     The LED strip  16  can be broken up in accordance with sections  40  by severing the tape (strip  16 ) along the circuit repeat joints  42  to create an infinitely variable length LED luminaire. Cuttable length segments or sections  40  provide scalable light engines ( 44 ) from a single source (AC bus  34 ). The AC bus bar  34  is integrated into the tape  16  and is only converted to DC locally at the LED chain. By integrating the power source into the tape  16 , each micro light engine  44  is powered independently. This increases the reliability of the total luminaire/device  10 . The micro drivers or power supplies  36  are stepped and repeated in each section  40 . The stepped configuration (each power supply  36  is connected along the AC bus  34 ) makes the wattage scalable and increases reliability. The LED circuitry  50  includes a capacitorless design with redundant circuits. 
     Once severed, the remaining unsevered sections  40  remain powered and include the same functions and operating parameters as the unsevered tape. In some embodiments, a dimmer circuit  52  may be provided on the LED strip  16  or in the junction box  14  and may be manually or automatically adjusted. 
     The embodiments described can provide greater reliability, and light output for in accordance with the present principles. The useful lifetimes of LEDs can far exceed the useful lifetimes of other bulbs. For example, LEDs can last for at least 100,000 hours or more. 
     The present principles may be employed in many applications. Some of these applications may include, e.g., cove lighting, hand rail illumination, slot fixtures, theater lighting, path of egress lighting, etc. 
     The repeat joints  42  may include demarcations for cutting the tape at the appropriate regions (between repeating light engine blocks). In one embodiment, the tape  16  can be torn by hand, cut by scissors or other tools. In other embodiments, the structure of the tape  16  is uniformly configured along its length. In still other embodiments, demarcations are placed inconspicuously (e.g., on the back of the tape  16 ). 
     Referring to  FIG. 6 , a method for configuring a lighting device is shown in accordance with illustrative embodiments. In block  102 , a lighting device is provided. The lighting device includes a junction box, a power cord coupled to the junction box and a tape connected to the junction box and electrically coupled to the power cord. The tape includes a plurality of light emitting diodes (LEDs) disposed in sections, each section including a repeating light engine block with the LEDs and a circuit repeat joint. 
     The repeating light engine block may include a micro power supply with an alternating (AC) to direct current (DC) converter and a rectifying circuit. The micro power supply distributes power from an AC bus running along a wireway in a casing of the tape. 
     In block  104 , the tape is cut to length at a circuit repeat joint to scale a dimension of the tape. The tape is flexible and the circuit repeat joints are separated by about 4 inches. The tape is configurable between about 4 inches to about 150 feet from a single voltage feed. 
     Having described preferred embodiments for scalable direct line voltage LED luminaire tape (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims. Having thus described aspects of the invention, with the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims.