LUMINAIRE WITH DYNAMICALLY CONTROLLED LIGHT DISTRIBUTION

Description

BACKGROUND

[0001] Light emitting diodes (LEDs) are commonly used as light sources in various applications. LEDs can be more energy-efficient than traditional light sources, providing much higher energy conversion efficiency than incandescent lamps and fluorescent light, for example. Furthermore, LEDs may radiate less heat into illuminated regions and afford a greater breadth of control over brightness, emission color and spectrum than traditional light sources. These characteristics make LEDs an excellent choice for various lighting applications, such as outdoor lighting, decorative lighting, or outdoor lighting.

[0002] Different applications may require different light distribution patterns. To this end, it is desirable for LEDs to be paired with the appropriate light fixture when used for indoor or outdoor lighting. For example, some lighting applications may desire light emissions that are more broadly spread than others. It is known from US 2007 / 0141864 A1 to punch individual bendable lead frames from a sheet. It is known from KR 2010 0003326 A, from WO 2014 / 179519 A2 and from JP 2009 158260 A to mount LEDs on a substrate which can be bent into a shape so that the substrate with its LEDs can be more optimally arranged inside a light fixture.SUMMARY

[0003] The invention is defined by the claimed illumination source and by the claimed method of fabricating a flexible printed circuit board for such an illumination source.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Like reference characters shown in the figures designate the same parts in the various embodiments. FIG. 1A is a diagram of an example of a flexible printed circuit board, according to aspects of the disclosure; FIG. 1B is a cross-sectional view of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure; FIG. 1C is a planar top-down view of a solder mask layer of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure; FIG. 1D is a planar top-down view of a metal layer of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure; FIG. 1E is a planar top-down view of a dielectric layer of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure; FIG. 1F is a planar top-down view of an adhesive layer of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure; FIG. 1G is a flowchart of a method of fabricating the flexible printed circuit board of FIG 1A, according to aspects of the disclosure; FIG. 2A is a perspective view of an example of an illumination source utilizing the flexible printed circuit board of FIG 1, according to aspects of the disclosure; FIG. 2B is a planar top-down view of the illumination source of FIG. 2A, according to aspects of the disclosure; FIG. 2C is a side view of the illumination source of FIG. 2A, according to aspects of the disclosure; FIG. 2D is a perspective bottom-up view of the illumination source of FIG. 2A, according to aspects of the disclosure; FIG. 3A is an exploded view of an example of a light fixture utilizing the illumination source of FIG. 2A, according to aspects of the disclosure; FIG. 3B is a side view of the combined light fixture of FIG. 3A, according to aspects of the disclosure; FIG. 4A is a cross-sectional side view of an example of a light guide that is part of the light fixture of FIG. 3, according to aspects of the disclosure; FIG. 4B is a planar top-down view of the light guide of FIG. 4A, according to aspects of the disclosure. DETAILED DESCRIPTION

[0005] The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Embodiments set forth in the claims encompass all available equivalents of those claims. According to aspects of the disclosure, a flexible printed circuit board, method of fabricating the flexible printed circuit board, illumination device (or light fixture) using of the flexible printed circuit board, electronics of the illumination device, and method of using the flexible printed circuit board to control illumination device, among others, are described. For example, in some embodiments, the flexible printed circuit board contains a substantially rectangular body having a plurality of segments. Each segment has a plurality of body contacts to which a light source, such as an LED, or set of light sources (also referred to as a bank of light sources) is attached. Flexible legs extend substantially perpendicularly from the body, one flexible leg extending from each segment. Each flexible leg contains at least one pair of leg contacts disposed proximate to a distal end of the leg from the body. The flexible printed circuit board is formed from a multilayer structure that comprises an adhesive layer configured to adhere the structure to a material contacting the adhesive layer, at least one pair of dielectric and metal layers, with one of the dielectric layers adjacent to the adhesive layer. Exposed portions of the metal layer through the dielectric layer form the leg contacts, and exposed portions of the metal layer through an overlying solder mask layer form the pair of body contacts.

[0006] The flexible printed board may be incorporated in a light fixture. The light fixture may include a light guide having an interior opening that defines an interior edge of the light guide. The light guide may be planar, and thus be formed as a light guide plate. An illumination source is inserted in the interior opening and includes a plurality of LEDs that are arranged to inject light into the light guide through the interior edge of the light guide. The LEDs are arranged around the circumference of a base that is part of the illumination source. The base may be thermally conductive. Equally, the base may be coupled to a heat-dissipating element that is disposed over the light guide. The heat-dissipating element may be arranged to receive heat generated by the LEDs via the thermally conductive base and dissipate the received heat.

[0007] Various types of light guides can be used to address different types of applications. Flat light guide panels may be used to cover applications ranging from intermediate batwings (typically ~45-60 degree beam angle) to concentrated lambertians for some outdoor (parking garages) and indoor (downlights) applications. Flat + chamfered outer edge light guide panels may be used for similar applications, but with higher efficiency targets and less cost constrained, can be used too. This geometry can also be used for spots applications. Wedge light guide panels may be used for applications demanding batwing light distributions with high beam angles (> 60 degrees) and high optical efficiency, such as for bollards or street lighting. The light guide panel may have a main flat surface facing the backside of the light engine to achieve good mechanical support and rigidity. The flat surface (or both surfaces in some cases) can include additional light extracting elements (such as ink dot patterns or 3D textures or also the electrically-controllable inks already proposed in a previous ID) to provide increased performance for light output, or added dynamic control of light distributions, or simply for light extraction from the flat light guide panels or for additional emitting surface uniformity purpose. The center hole from which light is injected can also be shaped circularly or be multifaceted (octagon for instance to match the number of LEDs or angular segments) to tune the light distribution as well. Planar facets allow to generate more concentrated beams in the horizontal planes. The outer light guide panel edge can also include a reflective layer (white or mirror tape, or white glue, or clear glue + white reflective or mirror film) to recycle the light that otherwise would escape and likely get absorbed in the housing.

[0008] Examples of different light fixtures are described more fully hereinafter with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example can be combined with features found in one or more other examples to achieve additional implementations.

[0009] 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. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0010] It will be understood that when an element such as a layer, region or substrate is referred to as being "on" or extending "onto" another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly onto" 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. It will be understood that these terms are intended to encompass different orientations of the element in addition to any orientation depicted in the figures.

[0011] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures.

[0012] FIGS. 1A-1F are diagrams of an example of a flexible printed circuit board, according to aspects of the disclosure. In particular, FIG. 1A is a top view of the flexible printed circuit board 100. The flexible printed circuit board 100 includes a body 108 and one or more legs 104. As shown, the flexible printed circuit board 100 contains multiple legs 104. The body 108 is substantially rectangular and the legs 104 extend substantially perpendicularly from the body 108.

[0013] The body 108 includes one or more segments 106 associated with a set of pairs of body contacts 102. Each pair of body contacts 102 is used to provide electrical connection to a different light source 110 mounted thereon (or otherwise attached thereto). Each set of pairs of body contacts 102 includes a single pair of body contacts 102 or multiple pairs of body contacts 102. Different segments 106 may contain the same number of pairs of body contacts 102, as shown, or one or more of the segments 106 may contain a different number of pairs of body contacts 102 from at least one other segment 106.

[0014] The set of light sources 110 within a particular segment 106 may be the same color or one or more of the light sources 110 within the segment 106 may be different colors. Similarly, in some embodiments, each segment 106 may contain a set of light sources 110 having the same color or set of colors. In other embodiments, one or more of the colors may be different in different segments 106. In some embodiments, each set of light sources 110 (the light sources 110 of a segment 106) may be independently controllable. In further embodiments, each light source 110 within the set of light sources 110 may be independently controllable via the body contacts 102 connected to each light source 110. In some embodiments, one or more of the segments 106 may not contain any light sources 110.

[0015] As shown in FIG. 1A, each of the legs 104 includes electrical connections, shown as leg contacts 104a, that are disposed at a distal end thereof. The leg contacts 104a of each leg are used to control the set of light sources 110 in a different one of the segments 106. Thus, in the embodiment shown in FIG. 1A, multiple light sources 110 of a particular segment 106 are controlled by a single pair of leg contacts 104a associated with the segment 106. As shown, test contacts on each leg 104 may be disposed between the body 108 and the leg contacts 104a. The test contacts may be used during testing of the flexible printed circuit board 100, either to test the connectivity between the leg contacts 104a and the body contacts 102 or connectivity to the set of light sources 110. To control the light sources 110, each leg 104 includes electrical connections and / or wiring to activate / deactivate one or more of the light sources 110 in the associated segment 106, change the brightness of one or more of the light sources 110 in the associated segment 106, change the color of light output of in the associated segment 106, and / or control other characteristics of the operation of the one or more of the light sources 110 in the associated segment 106. The set of light sources 110 in each segment 106 may be connected to one another in series, in parallel, and / or in any other suitable way. As above, the set of light sources 110 in each segment 106 may be configured to output the same color of light or different colors of light such as, for example, red, green, and blue. Additionally or alternatively, the set of light sources 110 in each of the segments 106 may output light having the same correlated color temperature (CCT). Additionally or alternatively, the light outputs of at least two of the light sources 110 in a segment 106 may have different CCTs.

[0016] FIG. 1B is a cross-sectional view of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure, while FIG. 1G is a flowchart of a method of fabricating the flexible printed circuit board of FIG. 1A, according to aspects of the disclosure. The flexible printed circuit board 100 may be a multilayer structure that contains at least one pair of metal and dielectric layers 114, 116 and a solder mask 112 on a topmost metal layer 114. A pressure-sensitive adhesive (PSA) 118 may be attached to the underside of a portion of the dielectric layer 116. The PSA 118 is a non reactive adhesive that forms a bond when pressure is applied without the use of a solvent, water, or heat. The PSA 118 may be between about 50 µm and 1 mm, but is typically around 100 µm. The dielectric layer 116 may be formed from polyimide, or any other suitable insulating material that is sufficiently flexible when of the desired thickness. The dielectric layer 116 may be between about 25 µm and 100 µm , sufficient to support the metal layer 114. As shown in FIG. 1G, the metal layer 114 may be formed on the dielectric layer 116 at operation 122. In different embodiments, the metal layer 114 may be deposited or plated on the dielectric layer 116. The metal layer 114 may be formed from copper, or any other suitable conductive material. The metal layer 114 may be between about 17.5 µm and 100 µm , nominally 70 µm or so.

[0017] In some embodiments, after formation of the metal layer 114 on the dielectric layer 116, leg contacts are formed at operation 124. In some embodiments, portions of the dielectric layer 116 may be removed by etching or other chemical or mechanical process to permit contact to the metal layer 114 at the appropriate location. In other embodiments, the portions of the dielectric layer 116 may not be removed. If a multilayer structure is used (operation 126) and the metal layer is not the final metal layer (operation 128), a new dielectric layer may be deposited or otherwise formed on underlying the metal layer at operation 130. The process may then return to operation 122.

[0018] If a multilayer structure is not used (operation 126) or the metal layer is the final metal layer (operation 128), the solder mask 112 may be deposited on the topmost metal layer 114 at operation 132. The solder mask 112 may be between about 25 µm and 50 µm . The solder mask 112, when applied, may have openings to expose portions of the topmost metal layer 114 to form the body contacts. The solder mask 112 may also have openings to expose portions of the topmost metal layer 114 to form the leg contacts, if not formed in the dielectric layer 116. In other embodiments, the openings in the solder mask 112 may be formed after application of the solder mask 112. The LEDs or other light sources may then be soldered or affixed to the solder mask 112. The PSA 118 may be applied at any point during the process shown in FIG. 1G, such as before the light sources are attached or before the solder mask is applied. The PSA 118 may be applied to areas to which the multilayer structure is attached, or at least areas other than the leg contacts.

[0019] FIG. 1C is a planar top-down view of a solder mask layer of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure. As shown in FIG. 1C, the solder mask 112 has openings for both the body and leg contacts. FIG. 1D is a planar top-down view of a metal layer of the flexible printed circuit board of FIG. 1A, according to aspects of the disclosure. As above, the metal layer 114 may be formed from copper, or any other suitable conductive material. As shown, the metal layer 114 is split into individual connections. The portion of the metal layer 114 corresponding to the leg 104 is split into two sections, each connected to a different body contact 102 of the body 108. The portion of the metal layer 114 corresponding to the body 108 is further split into multiple sections. Each section of the metal layer 114 is electrically isolated from each other section of the metal layer 114. The sections as shown in FIG. 1D are configured such that the set of light sources 110 in a segment 106 are series connected, with one of the pairs of body contacts 102 being electrically connected to another of the pairs of body contacts 102. In other embodiments, however, one or more of the light sources 110 in the set of light sources 110 may be independently addressable using the metal layer 114 via additional sections of the metal layer 114 or using a different (underlying) metal layer.

[0020] FIG. 1E is a planar top-down view of a dielectric layer of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure. The dielectric layer 116 may, as above, be formed from polyimide. FIG. 1F is a planar top-down view of an adhesive layer of the flexible printed circuit board of FIG 1A, according to aspects of the disclosure. As above, portions of the PSA 118 may be removed prior to adhesion to the dielectric layer 116 and / or surface to which the structure is attached. Although multiple pairs of body contacts are described as being associated with a single pair of leg contacts, multiple pairs of leg contacts may be used, e.g., one pair for each color LED if multiple LED colors are present within the LED segment. In addition, although pairs of contacts are described, in some embodiments, more than two contacts may be used (e.g., the LED or other light source may use more than two contacts).

[0021] FIGS. 2A-D show diagrams of an example illumination source according to aspects of the disclosure. In particular, FIG. 2A is a perspective view of an example of an illumination source utilizing the flexible printed circuit board of FIG. 1, FIG. 2B is a planar top-down view of the illumination source of FIG. 2A, FIG. 2C is a side view of the illumination source of FIG. 2A and FIG. 2D is a perspective bottom-up view of the illumination source of FIG. 2A. The flexible printed circuit board 100 is shown in FIGS. 2A-2D, as is a base 202 (also referred to as a core) to which the flexible printed circuit board 100 is attached.

[0022] As shown in FIGS. 2A-2D, the base 202 contains multiple sides 208 and a opening or opening 206 in the center of the base 202 that extends between the top and bottom surfaces of the base 202. As shown, the base 202 may be formed in an octagonal shape, although in other embodiments, the base 202 may be formed in a hexagonal, pentagonal, square or triangular shape, among others. The base 202 may thus have a round cross-section or a cross-section that is shaped as another type of polygon (e.g., a rectangle, a hexagon, a decagon, etc.). The legs 104 of flexible printed circuit board 100 may be routed around a bottom edge 204 of the base 202, along the bottom of the base 202, and into the opening 206 at the bottom of the base 202 as shown more clearly in FIG. 2D. In some embodiments, the legs 104 may extend into the opening 206 without coming out of the top of the base 202. As shown in the embodiment of FIG. 2D, the legs 104 extend entirely through the opening 206, to come out above the base 202. In some embodiments, the legs 104 may be attached to the inner sides of the opening 206 using the PSA, although in other embodiments, the legs 104 may not be attached to the inner sides of the opening 206. As shown in FIGS. 2A-2C, the legs 104 may be bent such that terminal portions of the legs 104 (which contain the leg contacts 104a) may be parallel to the top surface of the base 202. As shown, the bent portions of the legs 104 may extend from the edge of the opening 206 farther radially outward than the sides 208 of the base 202, or the set of light sources 110 of the segment 106. In other embodiments, the body 108 may be attached to the inner wall of the base 202. In this case, the legs 104 of flexible printed circuit board 100 may be bent to extend transverse to the outer wall of the base 202.

[0023] Although in the present example the base 202 includes one or more LEDs 110 on each of its sides 208, alternative implementations are possible in which at least one of the sides 208 does not have any LEDs mounted thereon. For example, in instances in which the base 202 is rail-shaped or has a rectangular cross-section, there may be LEDs disposed on only one or two of the sides. In some implementations, the base 202 of the illumination source 200 may be formed of metal or other heat dissipating material, and it may be configured to lead heat away from the flexible printed circuit board 100.

[0024] FIG. 3A shows an exploded view of an example of a light fixture 300 that utilizes the illumination source 200, according to aspects of the disclosure. The light fixture 300 may include, among others, a light guide 302 and a reflector 304 disposed over the light guide 302. The reflector 304 described in the various embodiments herein may be placed at the back of the light guide panel to reflect downwards the light that otherwise would be directed upwards. The specularity and diffusivity properties of the reflector 304 can be tuned to broaden the light distributions in both vertical and horizontal planes. Although the various light fixtures 300 show the reflector 304 as having a cylindrical shape with a substantially rectangular cross-section, like the other elements being formed in a shape circular or multi-sided (e.g., octangular) shape, the various aspects are not so limited. For example, the reflector may extend over the outer edge of the light guide and have a frustoconical shape. The frustoconical shape has a trapezoidal cross-section. The underlying light guide may retain the same frustoconical shape.

[0025] In some embodiments, the light fixture may include further elements, such as a diffuser disposed under the light guide 302, to diffuse light directed out from the light guide to an external environment. Although in the present example the light guide 302 is shaped as a disk having an interior opening (e.g., an opening in the middle of the disk or at another location), alternative implementations are possible in which the light guide 302 has a different shape. For example, the light guide 302 may be shaped as a rectangle or another polygon (e.g., octagon, hexagon, etc.), a rail, etc. The shape may be determined based on any applicable reason such as light distribution preference, physical space requirements, or the like. A light distribution preference may be based on an application of a light fixture, an environmental conduction (e.g., objects to illuminate, distance to illuminate, available ambient light, etc.), or a user input. It should be noted that although one or more specific light guide shapes are shown in the figures contained herein, the shape of a light guide may be adjusted to be any applicable shape that results in a desired light distribution.

[0026] The illumination source 200 may be connected to a PCB structure containing one or more control boards, such as printed circuit board (PCB) 326 for controlling the operation of the LEDs. As illustrated in FIG. 3, the PCB 326 may be situated above the base 202. In addition, a secondary control board 325 (or daughterboard) may be situated above the PCB 326 (or motherboard). The secondary control board 325 contain communication electronics through which a user device is able to wirelessly communicate lighting settings to set the lighting of the illumination source 200 via the PCB 326 and the secondary control board 325. As different protocols (e.g., WiFi, Bluetooth, Zigbee) may be used, and the secondary control board 325 may only support a single protocol, the secondary control board 325 may be removable (swappable) to change the protocol used to communicate the information from the user device. The secondary control board 325 may also communicate information to the user device, such as present lighting conditions, available lighting conditions, and error messages. The PCB 326 and the secondary control board 325 may be protected by a removable cover 327 formed from an opaque material, such as metal or plastic.

[0027] FIGS. 4A-B show the light guide 302 in further detail, in accordance with one particular implementation. FIG. 4A shows a vertical cross-section of the light guide 302 and FIG. 4B shows a top view of the light guide 302. As illustrated, in some implementations, the sidewalls 308 of the opening 310 of the light guide 302 may have one or more grooves (or indentations) 312 formed thereon. The sidewalls 308 may define an interior edge of the light guide 302 that faces the illumination source 200 when the illumination source 200 is at least partially disposed in the opening 310. The grooves may have any suitable shape, such as a circular shape, linear shape, a curved shape, etc. In the present example, the grooves 311 may be vertical, and they may have a linear shape that extends fully or partially between the top and bottom surfaces of the light guide 302. Additionally or alternatively, in some implementations, the grooves 311 may be horizontal, and they may have a linear shape that extends fully or partially around the circumference of the opening 310 of the light guide 302. The grooves 311 may have any suitable type of depth. In some implementations, the grooves 312 may be less than 1 mm deep. Additionally or alternatively, in some implementations, the grooves 311 may be less than 2 mm deep. Additionally or alternatively, in some implementations, the grooves 311 may be less than 3 mm deep. Additionally or alternatively, in some implementations, the grooves 311 may be less than 4 mm deep. Additionally or alternatively, in some implementations, the grooves 311 may be less than 5 mm deep. Additionally or alternatively, in some implementations, the grooves 311 may be less than 10 mm deep. Additionally or alternatively, in some implementations, the grooves 311 may be less than 20 mm deep, etc. Although in the present example the grooves 311 are formed on the interior edge of the light guide 302, alternative implementations are possible in which the same or similar groves are formed on the outer edge 344 of the light guide 302. In such instances, there may be additional LEDs that are optically coupled to the outer edge 344 of the light guide 302.

[0028] Although the light guide 302 has a flat surface in the example of FIGS. 4A-B, alternative implementations are possible in which the light guide has a recess formed in its surface . Furthermore, alternative implementations are possible in which the light guide 302 is tapered and or chamfered. Notably, the present disclosure is not limited to a specific configuration of the light guide 302.

[0029] As shown in FIG. 3, the illumination source 200 may be coupled to a mounting post 316. In some implementations, the illumination source 200 may be disposed at least partially inside the opening 310 in the light guide 302, as shown in FIGS. 4A-B, such that light emitted from the illumination source 200 is injected into the light guide 302 through the opening's sidewalls 308 of FIGS. 4A-B (e.g., the interior edge of the light guide 302). A reflector 320 may be disposed under the illumination source 200, as shown. As illustrated, in some implementations, the reflector 320 may be ring-shaped. In some implementations, the reflector 320 may have an inner diameter D1 that is smaller than the inner diameter Δ1 of the illumination source 200, as shown in FIG. 2B. Additionally or alternatively, the reflector 320 may have an outer diameter that is greater than the outer diameter Δ2 of the illumination source 200, as shown in FIG. 2B. Dimensioning the reflector 320 in this way may ensure a complete overlap between the illumination source 200 and the reflector 320, such that all, or a large portion, of light that is emitted by the illumination source 200 towards the reflector 320, without being injected into the light guide 302, is reflected back to be injected into the light guide 302 through the interior edge of the light guide.

[0030] In some implementations, as shown in FIG. 3, a cap 322 may be disposed under the light guide 302 and the reflector 320. The cap 322 may be formed of plastic, metal, and / or any other suitable type of material. In some implementations, the cap 322 may be formed of a reflective material, such that the surface of the cap 322 that faces the illumination source 200 is configured to reflect at least some of the light emitted from the illumination source 200 back towards the light guide 302. Additionally or alternatively, in some implementations, the cap 322 may be light transmissive (e.g., transparent or translucent). Additionally or alternatively, in some implementations, the cap 322 may be opaque.

[0031] In the example shown in FIG. 3, the opening 310 in the light guide 302 is a through-hole. However, alternative implementations are possible in which the opening is a blind hole. In such implementations, the reflector 320 and the cap 322 may be altogether omitted, while the illumination source 200 remains at least partially disposed inside the blind hole.

[0032] In some implementations, a heat dissipating element such as a housing / pan / heat spreading element 324 may be disposed above the illumination source 200, as shown. The pan 324 may be formed of metal and / or any other suitable type of thermally conductive material. In some implementations, the pan 324 may be thermally coupled to the base 202 of the illumination source 200. In such instances, heat that is generated by the LEDs on the illumination source 200 may be led away from the LEDs by the base 202 of the illumination source 200, into the pan 324, to be subsequently dissipated by the pan 324. In some implementations, the pan 324 may have an interior opening to allow the legs 104 of the flexible printed circuit board 100 (which is part of the illumination source 200) to be routed through the pan 324 and connected to circuitry, such as the PCB 326, that is overlying the pan 324. The pan 324 thus may form the back of the light engine 300, provide mechanical protection, and spread the heat generated by the LEDs 110 for good thermal dissipation since the pan may be contact with a center rod (shown below). The outer edge of the pan 324 may be used to shape optimally as the outer edge may significantly impact the overall photometric performance, mechanical protection, cosmetic aspect, and also ingress protection. If the light engine is not highly mechanical robust, and thermal dissipative is not too high, the reflector may be used as the housing.

[0033] In some implementations, the PCB 326 disposed over the pan 324 may include circuitry for individually addressing / controlling the operation of the LEDs or sets of the LEDs in the illumination source 200. The circuitry may be configured to control each segment 106 in the illumination source 200 independently of the remaining segments and / or each LED within the segment independently of each other LED within the segment. For example, each segment 106 may be turned on / off independently of the rest as a result of this arrangement. Additionally or alternatively, in some implementations, the brightness of each segment 106 may be changed independently of the rest as a result of this arrangement. Additionally or alternatively, in some implementations, the color of light output by each of the segments 106 may be changed independently of the rest as a result of this arrangement. Additionally or alternatively, in some implementations, the CCT of light output by each of the segments 106 may be changed independently of the rest as a result of this arrangement.

[0034] Although the examples presented throughout the disclosure are presented in the context of light emitting diodes, it will be understood that any other suitable type of light source can be used instead.

[0035] The figures provided herein are provided as an example only.

Claims

1. An illumination source (200) comprising a base (202) and a flexible printed circuit board (100) adapted for attachment to the base (202), wherein the base (202) comprises multiple sides (208) and a central opening (206) that extends between top and bottom surfaces of the base (202); the flexible printed circuit board (100) comprises - a flexible body (108), which is substantially rectangular, comprising a plurality of segments (106), each segment (106) comprising a set of pairs of body contacts (102) that are electrically isolated from the body contacts (102) of each other segment (106), wherein each pair of body contacts (102) provides electrical connection to an LED (110) mounted thereon; and - a plurality of flexible legs (104) extending substantially perpendicularly from the flexible body (108), each flexible leg (104): extending from a respective segment (106) of the plurality of segments (106), and comprising a pair of leg contacts (104a) disposed proximate to a distal end of the flexible leg (104) from the flexible body (108), each leg contact (104a) connected with a different body contact (102) of the respective segment (106), and each flexible leg (104) (104) of the flexible printed circuit board (100) adapted to be routed around a bottom edge (204) of the base (202), along the bottom surface of the base (202), and into the central opening (206).

2. The illumination source (200) of claim 1, wherein: the flexible printed circuit board (100) is formed from a multilayer structure that comprises: a dielectric layer (116), a metal layer (114) adjacent to the dielectric layer (116), and a solder mask layer (112) adjacent to the metal layer (114), the solder mask layer exposing portions of the metal layer (114) to form the body contacts (102).

3. The illumination source (200) of claim 2, wherein the multilayer structure further comprises: an adhesive layer (118) configured to adhere the multilayer structure to a material contacting the adhesive layer (118).

4. The illumination source (200) according to claim 2 or claim 3, wherein: the solder mask layer (112) exposes portions of the metal layer (114) to form the leg contacts (104a).

5. The illumination source (200) according to any of claims 2 to 4, wherein: the dielectric layer (116) exposes portions of the metal layer (114) to form the leg contacts (104a).

6. The illumination source (200) according to any of the preceding claims, wherein: each segment (106) comprises multiple pairs of body contacts (102) that are electrically isolated from each other.

7. The illumination source (200) according to claim 1, wherein: the central opening (206) in the base (202) comprises inner sides; and the flexible printed circuit board (100) is formed from a multilayer structure that comprises: an adhesive layer (118) configured to adhere the flexible legs (104) to the inner sides of the central opening (206), a solder mask layer (112) configured to expose, for each segment (106), the respective pairs of body contacts (102) and the pair of leg contacts (104a) of the respective flexible leg (104), and a plurality of alternating dielectric (116) and metal layers (114) disposed between the adhesive layer (118) and the solder mask layer (112), each metal layer (114) providing, for each segment (106), electrical connection between each leg contact (104a) and a body contact (102), each metal layer (114) electrically isolated from each other metal layer (114).

8. The illumination source (200) of claim 7, wherein: the solder mask layer (112) exposes portions of each metal layer (114) to form the leg contacts (104a).

9. The illumination source (200) of claim 8, wherein: the dielectric layer (116) exposes portions of each metal layer (114) to form the leg contacts (104a).

10. The illumination source (200) according to any of the preceding claims, wherein for each segment (106): each flexible leg (104) comprises secondary leg contacts disposed more proximate to the flexible body (108) than the leg contacts (104a).

11. The illumination source (200) according to any of the preceding claims, wherein: each segment (106) comprises a set of light sources (110), the set of light sources (110) comprises LEDs of different colors, and wherein each segment (106) comprises multiple pairs of leg contacts (104a), one pair for each LED color.

12. A method of fabricating a flexible printed circuit board (100) for an illumination source (200) according to any of claims 1 to 10, the method comprising the steps of: forming a metal layer (114) on the dielectric layer (116), the dilelectric layer (116) being flexible; applying a solder mask (112) over the metal layer (114), portions of the metal layer (114) exposed through the solder mask (112) forming the body contacts (102); and applying an adhesive (118) to the dielectric layer (116).

13. The method of claim 12, wherein: portions of the metal layer (114) exposed through the solder mask (112) form the leg contacts (104a).

14. The method of claim 12, further comprising: removing portions of the dielectric layer (116) to expose the metal layer (114) and form the leg contacts (104a) prior to applying the solder mask (112).

15. The method of claim 12, wherein: the adhesive (118) is applied to the dielectric layer (116) after formation of the body contacts (102).