Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/40—Details of LED load circuits
  • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
  • H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
  • H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
  • H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
  • H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
  • H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
  • H01L2933/0008—Processes
  • H01L2933/0033—Processes relating to semiconductor body packages
  • H01L2933/005—Processes relating to semiconductor body packages relating to encapsulations
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/48—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
  • H01L33/52—Encapsulations
  • H01L33/54—Encapsulations having a particular shape

Definitions

• the present inventive subject matter relates to lighting apparatus and methods and, more particularly, to solid state lighting apparatus and methods of forming.
• Solid state lighting arrays are used for a number of lighting applications.
• solid state lighting panels including arrays of solid state light emitting devices have been used as direct illumination sources, for example, in architectural and/or accent lighting.
• a solid state light emitting device may include, for example, a packaged light emitting device including one or more light emitting diodes (LEDs), which may include inorganic LEDs, which may include semiconductor layers forming p-n junctions and/or organic LEDs (OLEDs), which may include organic light emission layers.
• LEDs light emitting diodes
• OLEDs organic LEDs
• Solid state lighting arrays are used for a number of lighting applications.
• solid state lighting panels including arrays of solid state light emitting devices have been used as direct illumination sources, for example, in architectural and/or accent lighting.
• a solid state light emitting device may include, for example, a packaged light emitting device including one or more light emitting diodes (LEDs).
• LEDs typically include semiconductor layers forming p-n junctions.
• Organic LEDs (OLEDs), which include organic light emission layers, are another type of solid state light emitting device.
• a solid state light emitting device generates light through the recombination of electronic carriers, i.e. electrons and holes, in a light emitting layer or region.
• Solid state lighting panels are commonly used as backlights for small liquid crystal display (LCD) screens, such as LCD display screens used in portable electronic devices.
• LCD liquid crystal display
• LCD display screens used in portable electronic devices.
• solid state lighting panels as backlights for larger displays, such as LCD television displays.
• solid state light sources having high coloring rendering index (CRI) and/or high efficiency have been demonstrated, one problem with the large-scale adoption of such light sources in architectural applications is that commercial lighting systems utilize lamps with standardized connectors that are designed to be used with alternating current (ac) power, which may be phase cut using a phase cutting dimmer device.
• ac alternating current
• a solid state lighting source is provided or coupled with a power converter that converts ac power into dc power, and the dc power is used to energize the light source.
• the use of such power converters may increase the cost of the lighting source and/or the overall installation, and may reduce efficiency.
• Some attempts at providing solid state lighting sources have involved driving an LED or string or group of LEDs using a rectified ac waveform.
• the LEDs require a minimum forward voltage to turn on, the LEDs may turn on for only a part of the rectified ac waveform, which may result in visible flickering, may undesirably lower the power factor of the system, and/or may increase resistive loss in the system.
• a solid state lighting apparatus can include a substrate having first and second opposing surfaces, where at least one of the opposing surfaces is configured to mount devices thereon.
• a string of chip-on-board (COB) light emitting diode (LED) sets can be on the first surface of the substrate and coupled in series with one another.
• An ac voltage source input from outside the solid state lighting apparatus, can be coupled to the first or second surface of the substrate.
• a solid state lighting apparatus can include a rectifier circuit that is mounted on a surface of a substrate housed in the solid state lighting apparatus, coupled to an ac voltage source configured to provide a rectified ac voltage to the substrate.
• a current source circuit can be mounted on the surface of the substrate and coupled to the rectifier circuit.
• a string of light emitting diode (LED) sets can be mounted on the surface of the substrate, and coupled in series with one another and to the current source circuit.
• a plurality of current diversion circuits can be mounted on the surface of the substrate, where respective ones of which are coupled to respective nodes of the string and can be configured to operate responsive to bias state transitions of respective ones of the LED sets.
• At least the plurality of current diversion circuits includes discrete electronic component packages that can be mounted on the substrate.
• the LEDs in the string can be chip-on-board LEDs that are mounted on the surface of the substrate.
• the substrate can be a flexible circuit substrate, where the apparatus can further include a heat sink that can be mounted on an opposing surface of the substrate, and thermally coupled to the string of LED sets.
• the substrate can be a metal core printed circuit board (MCPCB).
• a solid state lighting apparatus can include a rectifier circuit that can be configured to be coupled to an ac power source to provide a rectified ac voltage.
• a current source circuit can be coupled to the rectifier circuit and a string of serially-connected LED sets can be coupled to an output of the current source circuit.
• At least one capacitor can be coupled to the output of the current source circuit.
• a current limiter circuit can include a current mirror circuit that is configured to limit a current through at least one of the LED sets to less than a current produced by the current source circuit and to cause the at least one capacitor to be selectively charged via the current source circuit and discharged via the at least one of the LED sets responsive to the rectified ac voltage applied to an input of the current source circuit.
• a plurality of current diversion circuits can be coupled to respective nodes between LEDs in the string and configured to be selectively enabled and disabled responsive to bias state transitions of the LED sets as a magnitude of the rectified ac voltage varies.
• the plurality of current diversion circuits can each include a transistor that can provide a controllable current path between a first node of the string and a terminal of the rectifier circuit and a turn-off circuit coupled to a second node of the string and to a control terminal of the transistor and that can be configured to control the current path responsive to a control input.
• the apparatus can also include a substrate having first and second opposing surfaces, where at least the string of serially- connected LED sets, the plurality of current diversion circuits, the rectifier circuit, and the current source circuit are mounted on the substrate.
• the LEDs in the string can be chip-on-board LEDs mounted on the substrate.
• the substrate can be a flexible circuit board, where the apparatus can further include a heat sink that is mounted on the substrate opposite and proximate to the string of LED sets.
• the substrate can be a metal core printed circuit board (MCPCB).
• a method of forming a solid state lighting circuit can be provided by placing a plurality chip-on-board light emitting diodes (LEDs) in a string configuration on a surface of a substrate.
• An encapsulant material can be applied over the plurality of chip-on-board LEDs and the encapsulant material can be formed into a layer covering the plurality of chip-on-board LEDs to provide lenses for the plurality of chip-on-board LEDs.
• the method can also include placing a plurality of current diversion circuits, including discrete electronic component packages, on the surface of the substrate.
• applying an encapsulant material can be provided by applying the encapsulant material to cover the plurality of chip-on-board LEDs and portions of the surface between ones of the plurality of chip-on-board LEDs.
• forming the encapsulant material into a layer can be provided by bringing a mold into contact with the encapsulant material to simultaneously form a layer covering the plurality chip-on-board LEDs to provide the lenses for the plurality chip-on-board LEDs, wherein the mold includes chip-on-board LED recesses positioned in a surface of the mold opposite the plurality of chip-on-board LEDs.
• the method can further comprise
• applying an encapsulant material can be provided by dispensing the encapsulant material separately onto the plurality of chip-onboard LEDs.
• applying an encapsulant material can be provided by dispensing the encapsulant material simultaneously onto the plurality of chip-on-board LEDs.
• forming the encapsulant material into a layer covering the plurality chip-on-board LEDs to provide lenses for the plurality chip-on-board LEDs can be provided by respective encapsulant barriers to a flow of the encapsulant material away from each of the plurality chip-on-board LEDs during application of the encapsulant material to provide a respective lens for each of the plurality of chip-on-board LEDs.
• the encapsulant barrier at least partially surrounds the LEDs and is configured to reduce a flow of the encapsulant material away from the LEDs during application of the encapsulant material to promote the formation of the lenses.
• the method can further include removing the encapsulant barriers from the lenses.
• a printed circuit board can include a substrate, that is configured for inclusion in a solid state lighting apparatus, where the substrate can have first and second opposing surfaces, where at least one of which is configured to mount a plurality of chip-on-board light emitting diodes (LEDs) thereon, and the substrate configured to couple to an ac voltage source input, from outside the solid state lighting apparatus, and configured for mounting a plurality of discrete current diversion circuits devices thereon coupled to respective nodes between ones of the LEDs and configured to be selectively enabled and disabled responsive to bias state transitions of the LED sets as a magnitude of a rectified ac voltage provided to the LEDs varies.
• LEDs chip-on-board light emitting diodes
• the substrate can be a metal core PCB.
• the first surface can be a conductive circuit pattern layer and the second surface can be a base metal layer having a greater thickness than the conductive circuit pattern layer, where the PCB can further include a dielectric layer that is between the conductive circuit pattern layer and the base metal layer.
• the substrate can be a flexible PCB.
• the PCB can further include a thermally conductive slug in the substrate at a particular position opposite where the string of chip-on-board LED sets are to be mounted thereon.
• the PCB can further include an encapsulant barrier, protruding from the surface, at least partially surrounding a position on the surface where at least one of the LEDs is to be mounted, configured to reduce a flow of an encapsulant material away from the LEDs during application of the encapsulant material to promote the formation of a lens on the at least one of the LEDs.
• FIG. 1 is a schematic block diagram illustrating a solid state lighting apparatus including a Light Emitting Diode (LED) driver circuit and an LED string circuit in some embodiments according to the invention.
• LED Light Emitting Diode
• Figure 2 is a schematic block diagram illustrating the LED driver circuit including a rectifier circuit and a current diversion circuit as shown in Figure l,and the LED string circuit coupled thereto in some embodiments according to the invention.
• Figure 3 is a schematic block diagram illustrating the LED driver circuit shown in Figures 1 and 2 further including a current limiter circuit and a capacitor coupled to the LED string circuit in some embodiments according to the invention.
• Figure 4A is a plan view of an exemplary circuit substrate including a rectifier circuit, an LED string circuit and other discrete electronic component packages thereon in the solid state lighting apparatus in some embodiments according to the invention.
• Figure 4B is a cross-sectional view of the exemplary circuit substrate shown in Figure 4A, in some embodiments according to the invention.
• Figure 4C is an alternative cross-sectional view of an LED string circuit portion of the exemplary circuit substrate shown in Figures 4A and 4B including a flexible circuit substrate in some embodiments according to the invention.
• Figure 4D is a plan view of an exemplary circuit substrate having an approximately symmetrical form-factor in some embodiments according to the invention.
• Figure 4E is a plan view of an exemplary circuit substrate having an approximately symmetrical form-factor in some embodiments according to the invention.
• Figure 5A is a plan view illustrating an exemplary circuit substrate including the rectifier circuit and LED string circuit coupled to a capacitor in some embodiments according to the invention.
• Figure 5B is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• Figure 5C is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• Figure 5D is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• Figure 5 ⁇ is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• Figure 5F is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• Figures 6-9 are cross-sectional views illustrating methods of forming a solid state apparatus on a circuit substrate including chip-on-board LEDs mounted thereon using a mold in some embodiments according to the invention.
• Figures 10-12 are cross-sectional views illustrating methods of forming a solid state lighting apparatus including chip-on-board LEDs using encapsulate barriers on a circuit substrate in some embodiments according to the invention.
• Figure 13A is a circuit schematic diagram illustrating an LED driver circuit coupled to an LED string circuit in some embodiments according to the invention.
• Figures 13B-D are circuit schematic diagrams illustrating current diversion circuits in some embodiments according to the invention.
• Figure 13E is a circuit schematic diagram illustrating an LED driver circuit coupled to an LED string circuit in some embodiments according to the invention.
• Figure 14 is a table illustrating performance data for an exemplary solid state lighting apparatus in some embodiments according to the invention.
• Figure 15 is a table illustrating performance data for an exemplary solid state lighting apparatus in some embodiments according to the invention.
• Figure 16 is an exemplary solid state lighting apparatus housed in a lighting fixture in some embodiments according to the invention.
• a lighting apparatus can be a device which illuminates an area or volume, e.g., a structure, a swimming pool or spa, a room, a warehouse, an indicator, a road, a parking lot, a vehicle, signage, e.g., road signs, a billboard, a ship, a toy, a mirror, a vessel, an electronic device, a boat, an aircraft, a stadium, a computer, a remote audio device, a remote video device, a cell phone, a tree, a window, an LCD display, a cave, a tunnel, a yard, a lamppost, or a device or array of devices that illuminate an enclosure, or a device that is used for edge or back-lighting (e.g., back light poster, signage, LCD displays), bulb replacements (e.g., for replacing ac incandescent lights, low voltage lights, fluorescent lights, etc.), lights used for outdoor lighting, lights used for security lighting, lights used for exterior residential lighting (wall mounts, post
• the present inventive subject matter further relates to an illuminated enclosure (the volume of which can be illuminated uniformly or non-uniformly), comprising an enclosed space and at least one lighting apparatus according to the present inventive subject matter, wherein the lighting apparatus illuminates at least a portion of the enclosed space (uniformly or non-uniformly).
• FIG. 1 is a schematic block diagram illustrating a solid state lighting apparatus 101 in some embodiments according to the invention.
• the solid state lighting apparatus 101 includes a light emitting diode (LED) driver circuit 105 coupled to an LED string circuit 110, both of which are mounted on a surface of a substrate 100.
• the LED driver circuit 105 is coupled to an ac voltage, which can provide current and voltage to the LED string circuit 110, and other circuits included in the apparatus 101, to emit light from the solid state lighting apparatus 101.
• LED light emitting diode
• the embodiments illustrated herein can make use of the direct application of ac voltage to the apparatus 101 (from an outside power source) without the inclusion of an "on-board" switched mode.
• the LED driver circuit 105 can, instead, provide a rectified ac voltage to the LED string circuit 110 to provide acceptable light from the apparatus in some embodiments according to the invention, based on the ac voltage signal provided directly to the solid state lighting apparatus 101.
• the solid state lighting apparatus 101 according to the invention can be utilized in any format lighting fixture, such as that illustrated in Figure 16.
• the LED driver circuit 105 can include components used to rectify the ac voltage, components to provide a current source to the LED string circuit 110, components for current diversion circuits, components for current limiting circuits (to limit the amount of current passing through at least one of the LEDs in the LED string circuit 110), and at least one energy storage device, such as a capacitor. It will be further understood that, in some embodiments according to the invention, at least some of these components can be mounted on the substrate 100 as discrete electronic component packages. Still further, in some embodiments according to the invention, some of the remaining circuits described herein can be integrated into a single integrated circuit package mounted on the substrate 100.
• the LED string circuit 110 can include a plurality of "chip-on-board” (COB) LEDs sets, coupled in series with one another, that are mounted on the substrate 100. Accordingly, the chip-on-board LEDs can be mounted on the substrate 100 without additional packaging which otherwise would be included if those LEDs were to be used in other applications where, for example, the LED is provided on a sub-mount, an intervening substrate, or other chip carrier to which the LED is mounted etc.
• COB chip-on-board
• Such other approaches are described, for example, in commonly assigned pending U.S. Application Serial No. 13/192,755 (Attorney Docket 5308-1364), where for example, LEDs can be located on a submount, located on a lower substrate to provide a stacked arrangement.
• the LED string circuit 110 can make use of packaged LED devices in the place of the COB LEDs, in some embodiments according to the invention.
• the LED string circuit 110 can include XML-HV LEDs available from Cree, Inc. of Durham N.C.
• the apparatus 101 can take the form of a relatively small form factor board, which is coupled directly to the ac voltage signal and provides the rectified ac voltage signal to the string circuit 110, without the use of an on-board switched mode power supply.
• the string circuit 110 can be made up of COB LEDs or LED devices on the board.
• the substrate 100 can be provided in any relatively small form factor (symmetrical or asymmetrical), such as those described herein in reference to Figures 4D, 4E, and 5A-5C. Further, the resulting small board with COB LEDs or LED devices included thereon operated by the direct application of the ac voltage signal (but without the on-board switched mode power supply) can provide a small packaged, efficient output lighting apparatus 101 that can perform as detailed in, for example, the tables shown in Figures 14 and 15, in some embodiments according to the invention.
• components that are described as being “mounted on” a substrate can be on the same surface of a substrate, or on opposing surfaces of the same substrate.
• components that are placed and soldered on the same substrate during assembly can be described as being
• the ac voltage signal can have any magnitude that is sufficient to operate the apparatus 101 in some embodiments according to the invention.
• the ac voltage signal can be 90 volts ac ,110 volts ac, 220 volts ac, 230 volts ac, 277 volts ac, or any intermediate voltage.
• the ac voltage signal is provided from a single phase ac voltage signal.
• the ac voltage signal can provided via voltage signals from two leads of a three phase ac voltage signal. Accordingly, the ac voltage signal can be provided from higher voltage ac voltage signals, regardless of the phase.
• the ac voltage signal can be provided from a three phase 600 volt ac signal.
• the ac voltage signal can be a relatively low voltage signal, such as 12 volts ac.
• FIG. 2 is a schematic block diagram illustrating a solid state lighting apparatus 101 shown in Figure 1 in some embodiments according to the invention.
• the LED driver circuit 105 includes a rectifier circuit 205 coupled to a current diversion circuit 210 and to the LED string circuit 110 that includes a plurality of LED string sets coupled in series with one another.
• the current diversion circuit 210 is coupled to selected nodes between ones of the LED sets in the string 110.
• the current diversion circuit 210 can be configured to operate responsive to the bias state transitions of those respective LED sets across which the current diversion circuit 210 is coupled. Accordingly, in some embodiments according to the invention, LED sets within the string can be incrementally activated and deactivated responsive to the bias states of the devices in the sets. For example, certain ones of the current diversion circuits can be activated and deactivated in response to the forward biasing of LED sets as a rectified ac voltage is applied to the LED string circuit 110.
• the current diversion circuits can include transistors that are configured to provide respective controllable current diversion paths around the LED sets between the selected nodes to which the current diversion circuit 210 is coupled.
• These transistors may be turned on/off by the biasing transitions of the LED sets which may be used to affect the biasing of the transistors.
• Current diversion circuits operating in conjunction with an LED string set are further described, for example, in commonly assigned co-pending U.S. Application Serial No. 13/235,127 (Attorney Docket 5308-1461).
• the rectifier circuit 205, the current diversion circuit 210, and the LED string circuit 110 can be mounted on the substrate 100 such that each of these components is provided on a single surface of the substrate 100.
• some of the circuits described herein are mounted on a first side of the substrate 100, whereas the remaining circuits are mounted on the opposing side of the substrate 100.
• the circuits described herein are mounted on the substrate 100 without the use of intervening substrates, sub-mounts, carriers, or other types of surfaces which are sometimes used to provide stacked types of assemblies in conventional arrangements.
• At least some of the components described in reference to Figure 2 can be mounted on the substrate 100 as discrete electronic component packages. Still further, in some embodiments according to the invention, some of the remaining circuits described in reference to Figure 2 can be integrated into a single integrated circuit package mounted on the substrate 100.
• exemplary solid state lighting apparatus 101 were constructed and operated according to the parameters illustrated in the table of Figure 14.
• the apparatus 101 made use of the current diversion circuits coupled to the string circuit 110 as shown in Figure 13, without use of the current limiter circuit and capacitor shown in Figure 13.
• the apparatus included 12 high voltage 16 junction COB LEDs, which each measured about 1.4mm x 1.4mm x .170mm.
• the data in the table of Figure 14 shows that the exemplary boards provided a lumens (Lm) range from about 704 Lm to about 816 Lm, over an efficacy (lumens per watt) range from between about 71 Lm/W to about 79 Lm/W, providing acceptable color points and relatively high power factors. It will be understood in some embodiments according to the invention, however, that greater output may be achieved by, for example, increasing the number of COB LEDs on the board or by increasing the current level used to drive the COB LEDs.
• FIG. 3 is a schematic block diagram illustrating the solid state lighting apparatus 101 including the LED driver circuit 105 (including the rectifier circuit 205 and current diversion circuit 210) coupled to a current limiter circuit 305 which is connected in parallel to a capacitor 310, both of which are coupled in series with the LED string circuit 110, all of which can be mounted on the surface of the substrate 100.
• the LED driver circuit 105 including the rectifier circuit 205 and current diversion circuit 210) coupled to a current limiter circuit 305 which is connected in parallel to a capacitor 310, both of which are coupled in series with the LED string circuit 110, all of which can be mounted on the surface of the substrate 100.
• the current limiter circuit 305 and the capacitor 310 may be utilized to reduce flicker which may otherwise result from the ac voltage provided to the solid state lighting apparatus 101.
• the capacitor 310 may be used to store energy near peak voltage and use that stored energy to drive the LED string 110 when the ac voltage magnitude is less than what may be required to forward bias the LEDs in the string 110.
• the current limiter circuit 305 can be configured to direct current to capacitor 310 so that energy is stored therein or configured to discharge the charge in the capacitor 310 through the LED string 110.
• Figure 3 shows that the capacitor 310 is used to store and deliver energy
• any type of electronic energy storage device can be used as alternatives to or, in combination with, the capacitor 310, such as inductors.
• current limiter circuits in conjunction with LED string circuits is further described, for example, in commonly assigned co-pending U.S. Application Serial No. 13/235,103 (Attorney Docket 5308-1459).
• the components shown in Figure 3 can be mounted on the same surface of the substrate 100.
• some of the circuits shown in Figure 3 can be mounted on a first surface of the substrate 100 whereas the remaining circuits are mounted on a second, opposing surface of the substrate 100.
• the LEDs included in the LED string circuit 110 can be chip-on-board LEDs which may be mounted on either surface of the substrate 100 or on a sub-mount or other substrate which is coupled to the substrate 100 as described, for example, in commonly assigned co-pending U.S. Application Serial No. 13/192,755 (Attorney Docket 5308-1364).
• exemplary solid state lighting apparatus 101 were constructed to provide the data illustrated in the table of Figure 15.
• the apparatus 101 made use of the current diversion circuits coupled to the string circuit 110 as shown in Figure 13, along with the use of the current limiter circuit and capacitor shown in Figure 13.
• the apparatus included 12 high voltage 16-junction COB LEDs, which each measured about 1.4mm x 1.4mm x .170mm.
• the data in the table of Figure 15 shows that the exemplary boards provided a Lm range from about 674 Lm to about 785 Lm, over an efficacy range from between about 69Lm/W to about 74 Lm/W, providing acceptable color points and relatively high power factors. It will be understood in some embodiments according to the invention, however, that greater output may be achieved by, for example, increasing the number of COB LEDs on the board or by increasing the current level used to drive the COB LEDs.
• Figure 4A is a plan view illustrating the solid state lighting apparatus 101 including the substrate 100 including the LED driver circuit 105 and the LED string circuit 110 mounted on the surface thereof in some embodiments according to the invention.
• Figure 4B is a cross-sectional view of a portion of the solid state lighting apparatus 101 shown in Figure 4A in some embodiments according to the invention.
• Figure 4C is a cross-sectional alternative view of a portion of the solid state lighting apparatus 101 where the substrate 100 includes a thermally conductive slug 417 embedded therein opposite the LED string circuit 110 in some embodiments according to the invention.
• the substrate 100 can be a printed circuit board (PCB).
• the PCB can be formed of many different materials that can be arranged to provide the desired electrical isolation and high thermal conductivity.
• the PCB can at least partially comprise a dielectric to provide the desired electrical isolation.
• the PCB can comprise ceramic such as alumina, aluminum nitride, silicon carbide, or a polymeric material such as polyimide and polyester etc.
• the boards can be flexible (sometimes referred to as a flexible printed circuit board). This can allow the board to take a non-planar or curved shape, with the LED chips also being arranged in a non-planar manner.
• the board can be a flexible printed substrate such as a Kapton® polyimide available from Dupont.
• the board can be a standard FR-4 PCB.
• the PCB can comprise highly reflective material, such as reflective ceramic or metal layers like silver, to enhance light extraction from the component.
• the board can include a dielectric layer 50 to provide electrical isolation, while also comprising electrically neutral materials that provide good thermal conductivity.
• Different dielectric materials can be used for the dielectric layer including epoxy based dielectrics, with different electrically neutral, thermally conductive materials dispersed within it. Many different materials can be used, including but not limited to alumina, aluminum nitride (A1N) boron nitride, diamond, etc.
• Different dielectric layers according to the present invention can provide different levels of electrical isolation with some embodiments providing electrical isolation to breakdown in the range of 100 to 5000 volts. In some embodiments, the dielectric layer can provide electrical isolation in the range of 1000 to 3000 volts.
• the dielectric layer can provide electrical isolation of approximately 2000 volts breakdown. In some embodiments according to the invention, the dielectric layer can provide different levels of thermal conductivity, with some having a thermal conductivity in the range of 1-40 w/m/k. In some embodiments, the dielectric layer can have a thermal conductivity greater than 10 w/m/k. In still other embodiments, the dielectric layer can have a thermal conductivity of approximately
• the dielectric layer can have many different thicknesses to provide the desired electrical isolation and thermal conductivity characteristics, such as in the range of 10 to 100 micro meters ( ⁇ ). In other embodiments, the dielectric layer can have a thickness in the range of 20 to 50 ( ⁇ ). In still other embodiments, the dielectric layer can have a thickness of approximately 35 ( ⁇ ).
• the substrate 100 can be a metal core PCB, such as a "Thermal-Clad” (T-Clad) insulated substrate material, available from The Bergquist Company of Chanhassen, Minn.
• the "Thermal Clad” substrate may reduce thermal impedance and conduct heat more efficiently than standard circuit boards.
• the MCPCB can also include a base plate on the dielectric layer, opposite the LED string circuit 110 , and can comprise a thermally conductive material to assist in heat spreading.
• the base plate can comprise different material such as copper, aluminum or aluminum nitride.
• the base plate can have different thicknesses, such an in the range of 100 to 2000 ⁇ , while other embodiments can have a thickness in the range of 200 to ⁇ . Some embodiments can have thickness of approximately 500 ⁇ .
• Such substrates may be mechanically robust compared to thick-film ceramics and direct bond copper arrangements. Accordingly, the metal core printed circuit board can be effective to transfer heat generated by LEDs included in the LED string circuit 110 away from the solid state lighting apparatus 101. It will be understood, however, that the substrate 100 can be any material which is suitable for the mounting of the LED driver circuit 105 and LED string circuit 110 thereon, which provides for sufficient thermal conduction away from the LED string circuit 110.
• the MCPCB includes a solder mounting layer on the bottom surface of the base plate that is made of materials that make it compatible for mounting directly to a heat sink, such as by solder reflow. These materials can comprise one or more layers of different metals such as nickel, silver, gold, palladium.
• the mounting layer can include a layer of nickel and silver, such a nickel having thickness in the range of 2 to 3 ⁇ and silver in the range of 0.1 to 1.0 ⁇ .
• the mounting layer can include other layer stacks such as electroless nickel of approximately 5 ⁇ , electroless palladium of approximately 0.25 ⁇ , and immersion gold of approximately 0.15 ⁇ .
• Direct soldering of the MCPCB to a heat sink can enhance thermal spreading of heat from the board to the heat sink by providing an increased thermal contact area between the two. This can enhance both vertical and horizontal heat transfer.
• the MCPCBs can provide different levels of thermal
• the size of the substrate 100 can vary depending on different factors, such as the size and number of the chip-on-board LED mounted thereon. For example, in some embodiments, in some combination of the chip-on-board LED mounted thereon.
• the substrate can be approximately 33 mm on each side. In some embodiments according to the invention, the components on the substrate can present a height of about 2.5 mm. Other dimensions can also be used for the substrate 100.
• the substrate 100 can be utilized in combination with heat sink structures mounted to, or incorporated within, the respective substrate to provide sufficient heat transfer away from the solid state lighting apparatus 101 as shown for example in Figure 4C.
• a flexible heat transfer tape such as GRAFIHXTM, available from GraphTech, International of Lakewood, OH, can be used to attach a heat sink to the substrate 100.
• the heat sink can be any thermally efficient material sufficient to conduct heat away from the substrate 100.
• the heat sink can be a metal, such as aluminum.
• the heat sink is graphite.
• the heat sink includes reflective surfaces to improve light extraction.
• the solid state lighting apparatus 101 includes the LED driver circuit 105 mounted on the surface thereof along with a plurality of chip-onboard LEDs arranged into a plurality of LED sets coupled in series with one another to provide the LED string circuit 110 (sometimes referred to as an array of COB LEDs).
• the COB LEDs of the string 110 can be arranged according to a particular pattern in approximately the center of the substrate 100. It will be understood, however, that the COB LEDs can be arranged in any way that is suitable to provide the light output desired from the solid state lighting apparatus 101.
• the COB LEDs can be arranged in an approximately circular array, a rectangular array, a random array, or a semi-random array.
• COB LEDs can be mounted onto a single circuitized substrate 100 with the "dead-space" between the COB LEDs being reduced, which may reduce the size of the solid state lighting apparatus 101 or the size allocated to the substrate 100 within the apparatus 101.
• a microchip or die such as an LED
• a microchip or die is mounted on and electrically interconnected to its final circuit substrate, instead of undergoing traditional assembly or packaging as an individual LED package or integrated circuit.
• the elimination of conventional device packaging when using COB assemblies can simplify the over-all process of designing and manufacturing, can reduce space requirements, can reduce cost, and can improve performance as a result of the shorter interconnection paths.
• a COB process can include three primary steps: 1) LED die attach or die mount; 2) wire bonding; and 3) encapsulation of the die and wires. These COB arrangements can also provide the added advantage of allowing for direct mounting and interface with the main apparatus heat sink.
• each chip in the array can have its own lens formed onto it to facilitate light extraction and emission with the first pass.
• First pass light extraction/emission refers to light emitted from a particular LED chip passing through the respective lens and the light's first pass from the LED chip to the surface of the primary lens. That is, the light is not reflected back, such as by total internal reflection (TIR), where some of the light can be absorbed.
• TIR total internal reflection
• This first pass emission can enhance the emission efficiency of the LED components by reducing LED light that can be absorbed.
• Some embodiments can comprise a high density of light emitting components while maximizing the light extraction, which can increase the efficiency of the respective solid state lighting apparatus.
• Some embodiments according to the present invention can be arranged in sub- groups of LED chips within the array, with each sub-group having its own primary lens for improved light extraction.
• the lens can be hemispheric, which can further increase light extraction by providing a lens surface that promotes fist pass light emission.
• LED arrays can include LED chips that emit light of the same color or of different colors (e.g. red, green and blue LED chips or subgroups, white LED and red LED chips or subgroups, etc.)
• Techniques for generating white light from a plurality of discrete light sources to provide desired CRI at the desired color temperature have been developed that utilize different hues from different discrete light sources. Such techniques are described in U.S. Patent No. 7,213,940, entitled “Lighting Device and Lighting Method", which is hereby incorporated herein by reference.
• a secondary lens or optic may be used in addition to the primary lens or optics, e.g. a larger secondary optic over multiple groups of emitters with primary optics. With each emitter or groups of emitters having their own primary lens or optic, embodiments according to the invention, may exhibit greater scalability to more readily provide for larger arrays of LEDs.
• the LED string circuit 100 can include hundreds of COB LEDs.
• the LED array can be COB mounted to a substrate 100 having characteristics that provide for improved operation.
• the substrate 100 can provide electrical isolation characteristics, which allows for board level electrical isolation of the COB LEDs.
• the board can have properties that provide an efficient thermal path to spread heat from the COB LEDs. Efficient thermal spreading of heat from the COB LEDs can result in improved LED chip reliability and color consistency.
• the substrate 100 can also be arranged to allow efficient mounting a primary heat sink.
• the substrate 100 includes features that allow it to be easily and efficiently mounted to the heat sink using mechanical means.
• the circuit board can comprise a material that allows it to be efficiently and reliably soldered to a heat sink, such as through reflow processes.
• the present invention can provide LED array arrangements that are scalable, such that some embodiments can have as few as three emitters and others can have as many as 10s or 100s of emitters.
• some of the components in the LED driver circuit 105 can be discrete electronic component packages mounted on the substrate 100 to provide, for example, the plurality of current diversion circuits mounted on the surface of the substrate 100. It will be further understood that other electronic component packages can be provided on the substrate 100 to provide the remainder of the circuits included in the solid state lighting apparatus 101.
• the substrate 100 can be a metal core multi-layered PCB including an upper metal layer used to provide interaction between the electronic component packages on the surface of the substrate 100.
• a lower metal (or base) layer 415 can be used to promote heat transfer away from the LED string circuit 110 and can be relatively thick compared to the upper metal layer 405.
• the upper metal layer 405 and the lower metal layer 415 are separated by a thermally conductive dielectric layer 410 that can electrically insulate the upper metal layer 405 from the lower metal layer 415 while still providing a thermal path from the LED string array 110 to the lower metal layer 415.
• the lower metal layer 415 can provide a heat sink for the transfer of heat away from the LED string circuit 110.
• a secondary heat sink can be attached to a lower surface of the lower metal layer 415 to provide for additional heat transfer away from the LED string circuit 110.
• the lower metal layer 415 can be a metal such as aluminum, copper, or beryllium oxide.
• the thermally conductive dielectric layer 410 can be a filler-matrix composite that acts as a bonding medium as well as a thermal path for heat conduction as well as providing an insulating layer between the upper metal layer 405 and the lower metal layer 415.
• the thermal conductivity of the thermally conductive dielectric layer 410 can be about 4 to about 16 times greater than conventional FR4 dielectrics.
• additional metal layers 405 can be provided within a thicker thermally conductive dielectric layer 410 to provide a two or more layer multi-core printed circuit board in some embodiments according to the invention.
• additional thermally conductive dielectric layers can be provided beneath the lower metal layer 415 such that the lower metal layer 415 is within the metal core printed circuit board, rather than on an exposed surface thereof.
• a flexible printed circuit board is provided as the substrate 100 having the LED string circuit 110 mounted thereon.
• a thermally conductive slug 417 can be embedded within the substrate 100 proximate to the LED string circuit 110 to provide for heat transfer away from the LED string circuit 110.
• the thermally conductive slug 417 can be a metal such as copper, aluminum or beryllium oxide. Other thermally conductive materials may also be used.
• Figure 4D is a plan view of an exemplary circuit substrate having an approximately symmetrical form-factor in some embodiments according to the invention.
• six LEDs (as part of the string circuit 110) are mounted on a central portion 460 of the substrate 100, and an ac voltage source input Jl is mounted on the substrate 100 proximate to the outer edge.
• the LEDs are in a first arrangement in the central portion 460, according to the desired light output from the apparatus 101.
• the plurality of LEDs are separated from a remainder of the electronic components mounted to the substrate 100 by a reserved portion 465 of the substrate 100, where the other electronic components are mounted on the substrate 100 only between the reserved portion 465 and outer perimeter 470 of the substrate 100. In some embodiments according to the invention, other electronic components are mounted in the reserved portion 465.
• an exemplary embodiment according to the invention was constructed where the center of the LEDs in the central portion 460 was located at a center of the substrate 100.
• the apparatus shown generated about 2000 Lumens at about 85 degrees Centigrade, using six XML-HV LEDs available from Cree, Inc. of Durham, N.C.
• the central portion 460 was about 21 mm in diameter and the overall board size was about 54 mm x 60 mm.
• the reserved portion 465 measured an additional 9.5 mm beyond the central portion 460.
• the total power provided to the apparatus was about 31.4 W, with about 20.6 W dissipated by the LEDs, at a total power dissipation of 25.2 W for the apparatus 101.
• Figure 4E is a plan view of an exemplary circuit substrate having another
• LEDs are mounted on the central portion 460 of the substrate 100, and an ac voltage source input Jl is mounted on the substrate 100 proximate to the outer edge.
• the LEDs are in a second arrangement in the central portion 460, according to the desired light output from the apparatus 101.
• the plurality of LEDs are separated from the remainder of the electronic components mounted to the substrate 100 by the reserved portion 465 of the substrate 100, where the other electronic components are mounted on the substrate 100 only between the reserved portion 465 and outer perimeter 470 of the substrate 100.
• other electronic components are mounted in the reserved portion 465.
• an exemplary embodiment according to the invention was constructed where the center of the LEDs in the central portion 460 was located at a center of the substrate 100.
• the apparatus shown generated about 800 Lumens at about 85 degrees Centigrade, using five XTE-HV LEDs available from Cree, Inc. of Durham N.C.
• the central portion 460 was about 16.1 mm in diameter and the overall board size was about 54 mm x 54 mm.
• the reserved portion 465 measured an additional 9.5 mm beyond the central portion 460.
• the total power provided to the apparatus was about 13.9 W, with about 9.5 W dissipated by the COB LEDs, at a total power dissipation of 11.5 W for the apparatus 101.
• Figure 5A is a plan view illustrating the solid state lighting apparatus 101 including the LED string circuit 110 and the LED driver circuit 105 mounted on the substrate 100 and including the capacitor 310 in some embodiments according to the invention.
• the LED driver circuit 105 shown in Figure 5 can also include the plurality of diversion circuits described herein, as well as the current limiter circuit 305 working in conjunction with the capacitor 310 to provide for operation of the LED string circuit 110 as described herein.
• the capacitor 310 can be mounted on the substrate to reduce the likelihood that the profile of the capacitor 310 may introduce a shadow into the light emitted by the solid state lighting apparatus 101. Accordingly, the capacitor 310 may be located near an outer perimeter of the substrate 100.
• the size of the substrate 100 can vary depending on different factors, such as the size and number of the chip-on-board LED mounted thereon.
• the substrate can be rectangular being approximately 33 mm x 46mm.
• the components on the substrate can present a height that is about equal to the height of the capacitor 310.
• the components on the substrate can present a height that is about equal to 13.5 mm. Other dimensions can also be used for the substrate 100.
• Figure 5B is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• six LEDs (as part of the string circuit 110) are mounted on a side portion 560 of the substrate 100.
• the LEDs are in the first arrangement in the side portion 560, according to the desired light output from the apparatus 101, and an ac voltage source input Jl is mounted on the substrate 100 proximate to the outer edge.
• the plurality of LEDs are separated from the remainder of the electronic components mounted to the substrate 100 by the reserved portion 565 of the substrate 100, where the other electronic components are mounted on the substrate 100 only between the reserved portion 565 and outer perimeter 570 of the substrate 100. In some embodiments according to the invention, other electronic components are mounted in the reserved portion 565.
• an exemplary embodiment according to the invention was constructed where the center of the LEDs in the central portion 460 was located about 17.5 mm from the top and bottom edges, about 15.2 mm from the right edge, of the substrate 100.
• the apparatus shown generated about 2000 Lumens at about 85 degrees Centigrade, using six XML-HV LEDs available from Cree, Inc. of Durham N.C.
• the central portion 560 was about 21 mm in diameter and the overall board size was about 71.3 mm x 35 mm.
• the reserved portion 565 measured an additional 9.5 mm beyond the central portion 560.
• the total power provided to the apparatus was about 31.4 W, with about 20.6 W dissipated by the LEDs, at a total power dissipation of 252 W for the apparatus 101.
• Figure 5C is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• five LEDs (as part of the string circuit 110) are mounted on the side portion 560 of the substrate 100.
• the LEDs are in the second arrangement in the side portion 560, according to the desired light output from the apparatus 101, and an ac voltage source input Jl is mounted on the substrate 100 proximate to the outer edge.
• the LEDs are separated from the remainder of the electronic components mounted to the substrate 100 by the reserved portion 565 of the substrate 100, where the other electronic components are mounted on the substrate 100 only between the reserved portion 565 and outer perimeter 570 of the substrate 100.
• other electronic components are mounted in the reserved portion 565.
• an exemplary embodiment according to the invention was constructed where the center of the LEDs in the central portion 560 was located about 16.2 mm from the top and bottom edges, about 12.827 mm from the right edge, of the substrate 100.
• the apparatus shown generated about 800 Lumens at about 85 degrees Centigrade, using five XTE-HV LEDs available from Cree, Inc. of Durham N.C.
• the central portion 560 was about 16.1 mm in diameter and the overall board size was about 66.875 mm x 32.4 mm.
• the reserved portion 565 measured an additional 9.5 mm beyond the central portion 560.
• the total power provided to the apparatus was about 13.9 W, with about 9.5 W dissipated by the LEDs, at a total power dissipation of 11.5 W for the apparatus 101.
• Figure 5D is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• a single LED (as part of the string circuit 110) is mounted on the side portion 560 of the substrate 100.
• the single LED is arranged in the side portion 560, according to the desired light output from the apparatus 101, and an ac voltage source input Jl is mounted on the substrate 100 proximate to the outer edge.
• the LED is separated from the remainder of the electronic components mounted to the substrate 100 by the reserved portion 565 of the substrate 100, where the other electronic components are mounted on the substrate 100 only between the reserved portion 565 and outer perimeter 570 of the substrate 100.
• other electronic components are mounted in the reserved portion 565.
• embodiments according to the invention can provide relatively small substrates that do not include an onboard switched mode power supply, but emit relatively high levels of light.
• a substrate can occupy an area of about 3240 mm 2 or less while emitting at least 2000 lumens.
• a portion of the substrate utilized by the LEDs (or COB LEDs) can be about 1384 mm 2 or less.
• the LEDs (or COB LEDs) can utilize about 40% or less of the entire area of the substrate.
• the reserve portions adjacent to the portions of the substrate utilized by the LEDs (or COB LEDs) can be about 16% or more of the length of the largest dimension of the substrate (i.e., length or width).
• a substrate can occupy an area of about 2900 mm 2 or less while emitting at least 800 lumens.
• a portion of the substrate utilized by the LEDs (or COB LEDs) can be about 814 mm 2 or less.
• the LEDs (or COB LEDs) can utilize about 30% or less of the entire area of the substrate.
• the reserve portions adjacent to the portions of the substrate utilized by the LEDs (or COB LEDs) can be about 18% or more of the length of the largest dimension of the substrate (i.e., length or width).
• a substrate can occupy an area of about 3240 mm 2 or less while emitting at least 2000 lumens. Further, in some
• a portion of the substrate utilized by the LEDs can be about 1384 mm 2 or less.
• the LEDs (or COB LEDs) can utilize about 40% or less of the entire area of the substrate.
• the reserve portions adjacent to the portions of the substrate utilized by the LEDs (or COB LEDs) can be about 13% or more of the length of the largest dimension of the substrate (i.e., length or width).
• a substrate can occupy an area of about 2144 mm 2 or less while emitting at least 800 lumens.
• a portion of the substrate utilized by the LEDs (or COB LEDs) can be about 814 mm 2 or less.
• the LEDs (or COB LEDs) can utilize about 38% or less of the entire area of the substrate.
• the reserve portions adjacent to the portions of the substrate utilized by the LEDs (or COB LEDs) can be about 14% or more of the length of the largest dimension of the substrate (i.e., length or width).
• Figure 5E is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• six LEDs devices (as part of the string circuit 110) are mounted on a side portion 580 of the substrate 100.
• the LEDs devices can be those available from Cree, Inc. of Durham N.C., which are described in, for example, U.S. Patent Application Nos. 13/027,006, filed on February 14, 2011, 13/178,791, filed on July 8, 2011, and 13/112,502, filed on May 20, 2011, the disclosures of which is incorporated herein by reference.
• the LED devices each include a respective submount 581 and a respective lens 582, in a first arrangement in the side portion 580, according to the desired light output from the apparatus.
• the LED devices are electrically coupled to the remainder of the electronic components on the substrate 100 by conductive traces 583.
• the plurality of LEDs devices are separated from the remainder of the electronic components by a reserved portion of the substrate 100, where the other electronic components are mounted on the substrate 100 outside the reserve portion of the substrate 100.
• other electronic components are mounted in the reserved portion.
• Figure 5F is a plan view of an exemplary circuit substrate having an approximately asymmetrical form-factor in some embodiments according to the invention.
• five LED devices (as part of the string circuit 110) are mounted on a side portion 590 of the substrate 100.
• the LEDs devices can be those available from Cree, Inc. of Durham N.C. which are described in, for example, U.S. Patent Application Nos. 13/027,006, filed on February 14, 2011, 13/178,791, filed on July 8, 2011, and 13/112,502, filed on May 20, 2011.
• the LED devices each include a respective submount 591 and a respective lens 592, in the side portion 590, according to the desired light output from the apparatus.
• the LED devices are electrically coupled to the remainder of the electronic components on the substrate 100 by conductive traces 593.
• the LED devices are separated from the remainder of the electronic components mounted to the substrate 100 by the reserved portion of the substrate 100, where the other electronic components are mounted on the substrate 100 outside the reserved portion of the substrate 100.
• other electronic components are mounted in the reserved portion.
• Figures 6-8 are cross-sectional views illustrating methods of forming a solid state lighting apparatus in some embodiments according to the invention.
• chip-on-board LEDs included in the LED string circuit 110 are mounted on the substrate 100.
• An encapsulate material 605 is applied over the chip-on-board LEDs.
• the encapsulate material 605 provides a continuous layer that covers the LEDs as well as portions of the substrate 100 between adjacent ones of the LEDs. Accordingly, the encapsulate material 605 may be applied to the chip-on-board LEDs essentially simultaneously with one another.
• the encapsulate material 605 can be used to form a lens over the chip-on-board LEDs.
• the encapsulate material 605 can include liquid silicone and/or liquid epoxy, and/or a volatile solvent material, such as alcohol, water, acetone, methanol, ethanol, ketone, isopropynol, hydrocarbon solvents, hexane, ethylene glycol, methyl ethyl ketone, and combinations thereof.
• the portion of the encapsulate material 605 that extends between adjacent ones of the chip-on-board LEDs may remain on the substrate 100 after completion of the assembly process, whereas in some embodiments according to the invention, the intervening encapsulate material 605 is removed from the substrate 100.
• the encapsulate material 605 can include other materials, such as optical conversion materials, diffusion materials and the like.
• a mold 710 is brought into contact with the encapsulate material 605 on the chip-on-board LEDs.
• the mold 710 includes recesses 711 in a lower surface thereof positioned opposite where the chip-on-board LEDs are to be located on the substrate 100.
• the recessed 711 have a shape that is to be given to the lenses on the chip-onboard LEDs.
• the mold 710 can be any material suitable for the molding of an the selected encapsulate material 605 (i.e. such as silicone) into a conformal or other profile layer.
• the mold 710 can be a metal, such as aluminum.
• the mold 710 can be Silicon or Silicon Carbide. Other materials can be used as the mold 710
• the mold 710 can have a release material applied thereto.
• a release material can be sprayed, or otherwise applied onto a surface of the mold 710 from which the substrate and chip-on-board LEDs are separated.
• the release material can be any material that will promote the removal of the chip-on-board LEDs and the substrate 100 from the mold 710.
• the release material can be a silicone based release agent.
• the encapsulate material 605 extending on the substrate 100 between adjacent ones of the chip-on-board LEDs may be compressed to a relatively thin layer, the encapsulate material 605 can remain on the substrate 100 despite not being provided as part of the lens for a particular chip-on-board LED.
• each of the chip-on-board LEDs on the substrate 100 is provided with a lens 815 from the molded encapsulate material 605.
• the encapsulate material 605 between the adjacent ones of the chip-on-board LEDs shown in Figure 8 may be removed.
• additional layers of encapsulate material 605 may be provided on the lenses 815 to provide additional optical features to the LED string circuit 110.
• additional discrete electronic component packages may be mounted on the substrate 100.
• the discrete electronic component packages making up the LED driver circuit 105 can be mounted on to the substrate 100 after the lenses 815 are formed from the encapsulate material 605.
• Figure 9 is a cross-sectional view illustrating methods of forming the solid state lighting apparatus 101 using a mold to form the lenses 815 in some embodiments according to the invention.
• the mold 910 further includes discrete electronic component package recesses 911 that are configured to accommodate the profile of the discrete electronic component packages 905 mounted on the substrate 100 that are outside the LED string circuit 110 having the encapsulate material 605 thereon. Accordingly, the discrete electronic component packages 905 can be mounted onto the substrate 100 along with the chip-on-board LEDs in the string circuit 110.
• the encapsulate material 605 can then be applied to the chip-on-board LEDs whereupon the mold 910 can be brought into contact with the encapsulate material 605 to form the lenses 815 while damage to the discrete electronic component packages 905 may be avoided by the inclusion of the discrete electronic component package recesses 911.
• Figures 10-12 are cross-sectional views illustrating methods of forming the solid state lighting apparatus 101 in some embodiments according to the invention.
• the chip-on-board LEDs are mounted on the substrate 100 and are at least partially surrounded by encapsulate barriers 1005 on the substrate 100. It will be understood that an upper surface of the encapsulate barriers 1005 are lower than the upper surfaces of the chip-on-board LEDs that are surrounded by the encapsulate barriers 1005.
• An encapsulate material 1015 is dispensed onto the chip-on-board LEDs.
• the encapsulate material 1015 is dispensed onto the chip-on-board LEDs using nozzles 1110.
• the encapsulate material 1015 is dispensed in an amount that is sufficient to provide for the formation of each respective lens 815 over the respective chip-on-board LED.
• the nozzle 1110 is moved over the chip-on-board LEDs to dispense the encapsulate material 1115 onto each of the respective chip-on-board LEDs according to a sequence.
• the nozzle 1110 may be located over the leftmost chip-on-board LED in the first position to distribute the encapsulate material 1115 onto the respective chip-on-board LED located just below the nozzle 1110. [00122] After dispensing the encapsulate material 1115, the nozzle 1110 is moved to a second position above the chip-on-board LED that is located immediately to the right of the leftmost chip-on-board LED. This procedure may be repeated to dispense the encapsulate material 1115 onto each of the chip-on-board LEDs included in the string circuit 110.
• a plurality of nozzles 1110 are prepositioned over at least two of the chip-on-board LEDs whereupon the encapsulate material 1115 is dispensed on to each of the chip-on-board LEDs essentially simultaneously with one another.
• the encapsulate barriers 1005 are configured to restrict the flow of an encapsulate material 1115 onto the respective chip-on-board LED to allow for the formation of the lens 815 to have the desired shape 1105. It will be understood that, as shown in Figure 10B, for example, the encapsulate barrier 1005 can at least partially surround each of the respective chip-on-board LEDs. For example, in some embodiments according to the invention, the encapsulate barrier 1005 may completely surround the respective chip-on-board LED. In other embodiments according to the invention, the encapsulate barrier 1005 may only partially surround the chip-on-board LED.
• the encapsulate barrier 1005 may have periodic or aperiodic gaps formed therein but still allow the formation of the lens 815 having the desired shape 1105 for the chip-on-board LED. It will also be understood that although the encapsulate barrier 1005 is shown as having essentially a rectangular cross- section, other forms of the encapsulate barrier 1005 may be used. For example, the encapsulate barrier 1005 may have a semi-circular shape or other geometric shape that provides adequate surface tension to promote the shape 1105 to the encapsulate material 1115 when dispensed on to the chip-on-board LED.
• the encapsulate barrier 1005 may have any shape that restricts the flow of the encapsulate material 1015.
• the encapsulate barrier 1005 has a square or rectangular perimeter shape to at least partially surround the chip-on-board LEDs . Other shapes can be used.
• Figure 12 is a cross-sectional view showing the removal of the encapsulate barrier 1005 from around the chip-on-board LED 1004 after formation of the lens 815 having a desired profile 1105.
• the encapsulate barrier 1005 can be etched from the outer edge of the lens 815 at a base of the chip-on-board LED to form a recess 1205 at an outermost edge of the lens 815 at the surface of the substrate 100.
• the encapsulate barrier 1005 is not removed from the lens 815.
• Figure 13A is a circuit schematic diagram illustrating an LED driver circuit coupled to an LED string circuit in some embodiments according to the invention.
• the apparatus 101 includes a string 110 of serially connected LED sets 110-1, 110-2, . . . , 110-N.
• Each of the LED sets 110-1, 110-2, . . . , 110-N includes at least one LED.
• individual ones of the sets may comprise a single LED and/or individual sets may include multiple LEDs connected in various parallel and/or serial arrangements.
• the sets of LEDs may be configured in a number of different ways and may have various compensation circuits associated therewith, as discussed, for example, in commonly assigned co-pending U.S. Application Serial No. 13/235,103 (Attorney Docket: 5308-1459).
• U.S. Application Serial No. 13/235,127 (Attorney Docket 5308-1461)
• Power is provided to the LED string 110 from a rectifier circuit 105 that is configured to be coupled to an ac power source 10 and to produce a rectified voltage v « and current i R therefrom.
• the rectifier circuit 105 may be included in the lighting apparatus 101 or may be part of a separate unit coupled to the apparatus 101.
• the apparatus 101 further includes respective current diversion circuits 130-1, 130- 2, . . . , 130-N connected to respective nodes of the string 110.
• the current diversion circuits 130-1, 130-2, . . . , 130-N are configured to provide current paths that bypass respective ones of the LED sets 110-1, 110-2, . . . , 110-N.
• the current diversion circuits 130-1, 130-2, 130-N each include a transistor Ql that is configured to provide a controlled current path that may be used to selectively bypass the LED sets 110-1, 110-2, . . . , 110-N.
• the transistors Ql are biased using transistors Q2, resistors Rl, R2, . . .
• the transistors Q2 are configured to operate as diodes, with their base and collector terminals connected to one another. Differing numbers of diodes D are connected in series with the transistors Q2 in respective ones of the current diversion circuits 130-1, 130-2, . . . , 130-N, such that the base terminals of current path transistors Ql in the respective current diversion circuits 130-1, 130-2, . . . , 130-N are biased at different voltage levels.
• Resistors Rl, R2, . . . , RN serve to limit base currents for the current path transistors Ql.
• the current diversion circuits 130-1, 130-2, . . . , 130-N are configured to operate in response to bias state transitions of the LED sets 110-1, 110-2, . . . , 110-N as the rectified voltage v R increases and decreases such that the LED sets 110-1, 110-2, . . . , 110-N are incrementally activated and deactivated as the rectified voltage VR rises and falls.
• the current path transistors Ql are turned on and off as bias states of the LED sets 110-1, 110-2, . . . , 110-N change.
• the string 110 of serially connected LED sets is also coupled in series with a current limiter circuit, which is embodied as a current mirror circuit 1420, although any type of current limiter circuit may be used in embodiments according to the invention.
• a current limiter circuit which is embodied as a current mirror circuit 1420, although any type of current limiter circuit may be used in embodiments according to the invention.
• One or more storage capacitors 310 are coupled in parallel with the string 110 of serially connected LED sets and the current mirror circuit 1420.
• the current mirror circuit 1420 may be configured to limit current through the string 110 of serially connected LED sets to an amount that is less than a nominal current provided to the string circuit 110.
• the current mirror circuit 1420 includes first and second transistors Ql, Q2 and resistors Rl, R2, R3 connected in the current mirror configuration.
• the current mirror circuit 1420 may provide a current limit of approximately (VLE D - 0 )/(R1 + R2) x(R2/R3).
• a voltage limiter circuit 1460 e.g., a zener diode, may also be provided to limit the voltage developed across the one or more storage capacitors 310. In this manner, the one or more storage capacitors 310 may be alternately charged via the rectifier circuit 105 and discharged via the string 110 of serially connected LED sets, which may provide more uniform illumination.
• the current mirror circuit 1420 is coupled to an LED set 1410, which is included among the plurality of LED sets in the string circuit 110. It will be understood that the LED set 1410 can include multiple LEDs coupled in parallel with one another.
• Figures 13B-D are circuit schematic diagrams illustrating current diversion circuits in some embodiments according to the invention.
• the transistors Q2 shown in Figure 13A as part of the current diversion circuits 130-1 - 130-N are replaced by diodes D in Figures 13B-D, to provide sufficient biasing of the respective base of the associated transistor Ql.
• each of the current diversion circuits 130-1 - 130-N stages includes a corresponding number of diodes D to provide the biasing otherwise provided by the transistor Q2.
• the first stage 130-1 includes two diodes for biasing
• the next stage 130-2 includes three diodes D for biasing.
• each of the stages 130-1 - 130-N can share the diodes D of the preceding stage for biasing.
• Figure 13E is a circuit schematic diagram illustrating an LED driver circuit coupled to an LED string circuit in some embodiments according to the invention.
• Figure 13E shows the current diversion circuits of Figures 13B-D used in the place of the current diversion circuits 130-1 - 130-N.
• the base voltage of Ql is about equal to the voltage drop of (D1+D2).
• the base voltage of Q2 is about equal to the voltage drop of (D1+D2+D3).
• the base voltage of QN is about equal to the voltage drop of (D1+D2+.. ,+DN).
• the current diversion circuits can be fabricated as an array of diodes and a block of transistors.
• the array of diodes and the block of transistors can be integrated together or separated from one another.
• the term light emitting diode may include a light emitting diode, laser diode and/or other semiconductor device which includes one or more semiconductor layers, which may include silicon, silicon carbide, gallium nitride and/or other semiconductor materials, a substrate which may include sapphire, silicon, silicon carbide and/or other microelectronic substrates, and one or more contact layers which may include metal and/or other conductive layers.

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• 2012
  • 2012-07-19 EP EP12817399.4A patent/EP2737780A1/de not_active Withdrawn
  • 2012-07-19 CN CN201280044036.9A patent/CN103907401B/zh active Active
  • 2012-07-19 WO PCT/US2012/047344 patent/WO2013016122A1/en active Application Filing
  • 2012-07-27 TW TW101127345A patent/TW201311053A/zh unknown

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