具体实施方式：
[0027]FIG. 1A is a diagram illustrating a LED illumination system 100 with multiple millimeter-scale spaced-apart LEDs 120 that form a sparse array and associated micro-optics 130 supported by a substrate 110. LED activation and light intensity can be controlled by controller 140. Light emitted from LEDs 120 follow light beam paths 150. The light beam paths can be substantially distinct or at least partially overlapping as indicated in FIG. 1. In some embodiments, the light beams can be used to illuminate a light diffuser panel. In other embodiments to be discussed with respect to FIG. 5, the LEDs 120 can be used to direct light into a light guide plate.
[0028]In some embodiments, at least some LEDs 120 are sized between 30 microns and 500 microns in length, width, and height. The micro-optics 130 are sized to be less than 1 millimeter in length, width, and height and are positioned over at least some of the LEDs 120. Typically, the micro-optics are sized to be similar or larger in size than the LEDs 120. In some embodiments the height of the LEDs 120, their supporting substrate and any electrical traces, and associated micro-optics 130 is less than 5 millimeters in combination.
[0029]The controller 140 is connected to selectively power groups LEDS 120 to provide different light beam patterns 150. The controller 140 can be mounted on, beneath, or adjacent to substrate 110. Alternatively, the controller can be mounted separately from the substrate 110 and use wired connections, board connected electrical traces, or another suitable interconnect mechanism. The LED controller 140 can include necessary circuitry so as to enable the operation of the plurality of LEDs 120. The LED controller can be unitary or be composed of multiple distinct modules in wired or wireless interconnection. For example, the LED controller 140 can include a separate power supply, a wireless interconnect, and remote logic on a dedicated light interface device or app supported by a smartphone.
[0030]The substrate 110 can include a laminated printed circuit board, a ceramic board, glass board, or plastic board. The substrate can be rigid or flexible. Furthermore, the substrate 110 can include the necessary traces and circuitry to enable individual or grouped operation of the LEDs 120. Electrical connection between controller 140 and LEDs 120 can be formed by direct wiring, electrical trace layout, side or bottom vias, or suitable combinations thereof. In certain embodiments, transparent conductors such as indium tin oxide (ITO) can be used to form top or side contacts.
[0031]In some embodiments, each LED can be separately controlled by controller 140, while in other embodiments groups of LEDs can be controlled as a block. In still other embodiments, both single LEDs and groups of LEDs can be controlled. To reduce overall data management requirements, the controller 140 can be limited to on/off functionality or switching between relatively few light intensity levels. In other embodiments, continuous changes in lighting intensity are supported. Both individual and group level control of light intensity is contemplated. In one embodiment, overlapping or dynamically selected zones of control are also possible, with for example, overlapping groups of LEDs 120 being separately controllable despite having common LEDs depending on lighting requirements. In one embodiment, intensity can be separately controlled and adjusted by setting appropriate ramp times and pulse width for each LED using a pulse width modulation module within controller 140. This allows staging of LED activation to reduce power fluctuations, and to provide superior luminous intensity control.
[0032]The LEDs 120 can include but are not limited to LEDs formed of sapphire or silicon carbide. The LEDs 120 can be formed from an epitaxially grown or deposited semiconductor n-layer. A semiconductor p-layer can then be sequentially grown or deposited on the n-layer, forming an active region at the junction between layers. Semiconductor materials capable of forming high-brightness light emitting devices can include, but are not limited to, Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. In certain embodiment, laser light emitting elements can be used.
[0033]Color of emitted light from the LEDs 120 can be modified using a phosphor contained in glass, or as a pre-formed sintered ceramic phosphor, which can include one or more wavelength converting materials able to create white light or monochromatic light of other colors. All or only a portion of the light emitted by the LEDs 120 may be converted by the wavelength converting material of the phosphor. Unconverted light may be part of the final spectrum of light, though it need not be. Examples of common devices include a blue-emitting LED segment combined with a yellow-emitting phosphor, a blue-emitting LED segment combined with green- and red-emitting phosphors, a UV-emitting LED segment combined with blue- and yellow-emitting phosphors, and a UV-emitting LED segment combined with blue-, green-, and red-emitting phosphors. In some embodiments, individually controllable RGB (three LEDs) or RGBY (four LEDs) can be positioned under a single micro-optic. This allows for precise color control of emitted light. Typically, such RGB LEDs are spaced sufficiently far apart that color mixing will occur in the far field.
[0034]Direction, beam width, and beam shape of light emitted from each LED 120 can be modified by micro-optics 130. Micro-optics 130 can be a single optical element or a multiple optic elements. Optical elements can include converging or diverging lenses, aspherical lens, Fresnel lens, or graded index lens, for example. Other optical elements such as mirrors, beam diffusers, filters, masks, apertures, collimators, or light waveguides are also included. Micro-optics 130 can be positioned at a distance from the LEDs that allows receipt and redirection of light from multiple LEDs 120. Alternatively, micro-optics 130 can be set atop each LED 120 to individually guide, focus, or defocus emitted LED 120 light. Micro-optics 130 can be directly attached to the LEDs 120, attached to LEDs 120 via a transparent interposer or plate, or held at a fixed distance from LEDs 120 by surrounding substrate attachments (not shown).
[0035]In one embodiment, LEDS are situated no further apart from each other than is necessary to present a substantially uniform visual appearance and provide a substantially uniform light beam. This requires that point-like sources be separated by distance that defines an angle smaller than the resolvable angular resolution for a user viewing at a normal distance (e.g. the distance from a standing or sitting user to light in a ceiling). FIG. 1B illustrates this with a graphic 160 illustrating a Rayleigh distance separation of millimeter-scale spaced apart LEDs and micro-optics. As seen in graph 160, pairs of LEDs 162, 164, and 166 are separated by an increasingly smaller distance. LEDs 162 are separated from each other by a distance and corresponding viewable angular separation at a distance (e.g. typically 1-2 meters) sufficient to distinguish each LED as a separate light source. A user looking at the LEDs would clearly see two distinct bright spots 182 having distinct dual light intensity peaks 172.
[0036]Placing the LEDs closer together can eliminate the perception of distinct bright spots. LEDs 166 are so closely spaced that the individual light intensity peaks from each LED beam are combined into a single peak 176 that presents a generally uniform visual impression, with some slight brightening 186 in the center.
[0037]Placing the LEDs 164 at an intermediate distance determined to be a Rayleigh distance separation or smaller can provide light intensity peaks 174 that are basically indistinguishable, giving a generally uniform visual impression 184. Rayleigh distance can be determined by considering diffraction through a circular aperture, which is:
θ=1.220λD
where θ is the angular resolution (radians), λ is the wavelength of light, and D is the pupil diameter of a user viewing the separated LEDs. Determining the Rayleigh distance allows a further determination of LED spacing for a user viewing the LEDs at a distance typically between 1-2 meters distant. Typically, this LED separation distance will be 1 millimeter or less for sub-millimeter sized LEDs with associated micro-optics. In some embodiments, this distance can be increased by providing diffuser layers, wide beam optics, or mirror systems. Unfortunately, this reduces ease of manufacture and increases both the Z-height and expense of the LED systems.
[0038]FIG. 1C is a diagram illustrating a low Z-height LED illumination system 190 with multiple millimeter-scale spaced apart LED units 192 formed from a combination of LEDs 194 and sheet embedded micro-optics 195. The LEDs 194 are supported by a substrate 196 (e.g. a printed circuit board or ceramic substrate that supports electrical traces or vias) that has attached heat spreader fins 198. The total Z-height 199 of the system is minimized, with a Z-height typically being less than 1 centimeter for millimeter or less sized LED sources. In some embodiments, Z-height for the LED illumination system 190 is set to be no greater than five (5) times the height of the LEDs 194.
[0039]Low Z-height systems can support various light beam orientations. For example, FIG. 2 illustrates an illumination system 200 with multiple millimeter-scale spaced apart LEDs 210 supported on a substrate 220. The multiple millimeter-scale spaced apart LEDs can be symmetrically arranged in lines or arrays. Alternatively, they can be arranged to have non-symmetric, irregular spacing. Every LED 210, or selected subgroups of LEDs 210, can be spaced at a Rayleigh distance separation or smaller. One-dimensional, two-dimensional, and three-dimensional non-symmetric or irregular layouts of LEDs with associated micro-optics is contemplated. Two-dimensional layouts can be constructed from adjacent or contiguous positioning of one-dimensional substrates. Three-dimensional layouts can be constructed from multiple stacked layers of two-dimensional substrates. Stacked substrates can be transparent, or include defined apertures offset from supported LEDs to permit exit of light from lower layers. In other embodiments, symmetrical one-dimensional, two-dimensional, and/or three-dimensional arrays of LEDs can be used, as well as combinations of symmetrical and non-symmetrical layouts.
[0040]FIG. 2 also illustrates a light guide plate 230 formed to include optics or other light modification structures positioned near or adjacent to each of the LEDs 210. Optical structures can be defined by embossing, etching, or additive emplacement on one or both sides of the light guide plate. For example, circular cavities 232 or pyramidal cavities 234 can be defined on one side, with additively manufactured lens provided on the opposing side. Additionally, dots can be printed, lines scratched, or cavities etched to affect light exit from the light guide plate 230.
[0041]FIG. 3 illustrates another embodiment of a low Z-height light guide plate system 300 in which LEDS 310 are attached directly to a light guide plate surface (336) or attached wholly (332) or partially (334) within a defined cavity in a light guide plate 330. Every LED 310, or selected subgroups of LEDs 310, can be spaced at a Rayleigh distance separation or smaller. In some embodiments, the light guide plate has a thickness from 50 to 100 microns, 100 to 500 microns, 0.5 to 1 mm, 1 mm to 5 mm, or 5 mm to 10 mm. In certain embodiments, LEDs 310 have a width from 30 microns to 500 microns. In other embodiments, LEDs 310 have a width and/or length from 5 to 10 μm, 10 to 50 μm, or 50 to 500 μm. In certain embodiments, each of the LEDs 310 has with a height from 2 to 10 μm, 10 to 200 μm, or 200 to 500 μm.
[0042]Attachment methods may include adhesive attachment. In some embodiments, pick and place machines can be used to individually position LEDs 310. In other embodiments, transfer forms or tacky sheets can be used to transfer multiple LEDs at the same time. In those embodiments including cavity attachment sites, numbers of LEDs can be placed and mechanically shaken on the light guide plate until the LEDs drop into suitable cavities. As other examples, elastomer stamps or electrostatic stamp (or other transfer device), can be used for pick-up and transport to a light guide plate. In some embodiments this process can be performed in in parallel, with dozens to hundreds LEDs transferred in a single pick-up-and-print operation.
[0043]LED power and control can be provided by applied conductive traces that are connected to suitable control and power circuitry. The conductive traces can be formed from conductive inks, conductive polymers, solder, conducting graphene, or other suitable material that can be lithographically or directly printed, or applied by stamping, or other suitable application method.
[0044]FIGS. 4A and 4B respectively illustrate in side (FIG. 4A) and top view (FIG. 4B) another embodiment 400. A low profile glare reduction structure 450 is situated over LEDs 410 that are attached to a substrate 420. Shields can be formed from a light blocking or reflective material the limits glare by reducing off-axis light beams. Every LED 210, or selected subgroups of LEDs 210, can be spaced at a Rayleigh distance separation or smaller.
[0045]FIG. 5 illustrates an illumination system 500 with multiple millimeter-scale spaced apart LEDs 520 and micro-optics 530 with both on-axis (e.g. micro-optic 532) and off-axis (e.g. micro-optic 532) associated micro-optics.
[0046]FIG. 6 illustrates an illumination system 600 with multiple millimeter-scale spaced apart LEDs 320 with associated micro-optics 330, arranged to have non-symmetric, irregular spacing. One-dimensional, two-dimensional, and three-dimensional non-symmetric or irregular layouts of LEDs 620 with associated micro-optics 630 is contemplated. Two-dimensional layouts can be constructed from adjacent or contiguous positioning of one-dimensional substrates. Three-dimensional layouts can be constructed from multiple stacked layers of two-dimensional substrates. Stacked substrates can be transparent, or include defined apertures offset from supported LEDs 620 to permit exit of light from lower layers. In other embodiments, symmetrical one-dimensional, two-dimensional, and/or three-dimensional arrays of LEDs 320 can be used, as well as combinations of symmetrical and non-symmetrical layouts.
[0047]FIG. 7 illustrates an illumination system 700 with multiple millimeter-scale spaced apart LEDs 720 embedded in a substrate 710, with an overlaying continuous optical plate 720 including aspheric optics. LEDs 720 can be positioned by a pick and place machine or other suitable carrier in multiple holes defined in substrate 410, Alternatively, epoxy, thermoset plastics, plastic molds, or similar substrates can be defined around LEDs 420 held in position. The plate 720 can be adhesively attached to the substrate 710. The plate can include on or off-axis micro-optics, or irregular aspheric micro-optics as shown. In certain embodiments, spherical optics can be used.
[0048]FIG. 8 illustrates an illumination system 800 with multiple millimeter-scale spaced apart LEDs 520 embedded in a transparent, flexible substrate 810. Micro-optics 830 can be attached to the substrate 810. This design is of particular use for architectural applications that require corner or curved surface mounting.
[0049]FIG. 9 is a top view illustrating two dimensional LED layout with filled areas, linear features, and regular and irregular curves. For example, feature 960 is a narrow linear structure supporting a one-dimensional array of LEDs, while feature 962 supports a curved one-dimensional array of LEDs. Feature 964 is a two-dimensional array (which can be radially symmetric as shown). Alternatively, rectangular, clumped, spiral, or other layouts are supported. Feature 966 can be an irregular shaped curve.
[0050]FIG. 10 illustrates a process 1000 for manufacture and calibration of multiple millimeter-scale spaced apart LEDs with associated micro-optics. In a first step 1010 are positioned with respect to a supporting substrate. A pick and place machine or other suitable device for holding and positioning hundreds or thousands of LEDs can be used. In step 1020, connecting traces are attached to the LEDs to allow later attachment to a controller. In step 1030, micro-optics are attached. In step 1040, calibration of intensity and light beam width/direction is conducted to correct for non-operating LEDs or misaligned micro-optics.
[0051]The disclosed low Z-height systems can be used in various lighting applications. For example, downlights able to provide 1,500 lumens can be constructed with 300 mini LEDs of 0.2×0.2 mm and further being 25 d with 1.1 mm optic height. The specific light pattern can take any shape including line, square, or open circle. In another application, spotlights that are track mounted or ceiling recessed can be constructed to provide 1,500 lm with 300 mini LEDs of 0.2×0.2 mm and further being 15 d with 2.0 mm optic height. An optional 2 mm high glare shield can also be used. Such lights can be embedded in the track system or can become part of a suspended light system. In still another embodiment, high intensity stadium lights able to provide 10,000 lm units can be constructed from 1,250 LEDs/unit. Even such powerful lighting systems will only require a 2.0 mm optic height. Mobile lighting applications are also supported. For example, a camera flash system can be designed to use 100 LEDs sized from 0.1 to 0.2 mm. The LEDs can be of one or more colors, and can be arranged to be selectively activated to provide a required flash light intensity at a desired color temperature.
[0052]Programmable light emitting arrays such as disclosed herein may also support a wide range of applications that benefit from fine-grained intensity, spatial, and temporal control of light distribution. This may include, but is not limited to, precise spatial patterning of emitted light from blocks or individual LEDs. Depending on the application, emitted light may be spectrally distinct, adaptive over time, and/or environmentally responsive. In some embodiments, the light emitting arrays may provide pre-programmed light distribution in various intensity, spatial, or temporal patterns. The emitted light may be based at least in part on received sensor data and may be used for optical wireless communications. Associated optics may be distinct at single or multiple LED level. An example light emitting array may include a device having a commonly controlled central block of high intensity LEDS with an associated common optic, whereas edge positioned LEDs may have individual optics. Common applications supported by light emitting LED arrays include camera or video lighting, architectural and area illumination, and street lighting.
[0053]Programmable light emitting arrays may be used to selectively and adaptively illuminate buildings or areas for improved visual display or to reduce lighting costs. In addition, light emitting arrays may be used to project media facades for decorative motion or video effects. In conjunction with tracking sensors and/or cameras, selective illumination of areas around pedestrians may be possible. Spectrally distinct LEDs may be used to adjust the color temperature of lighting, as well as support wavelength specific horticultural illumination.
[0054]Street lighting is an important application that may greatly benefit from use of programmable light emitting arrays. A single type of light emitting array may be used to mimic various street light types, allowing, for example, switching between a Type I linear street light and a Type IV semicircular street light by appropriate activation or deactivation of selected LEDs. In addition, street lighting costs may be lowered by adjusting light beam intensity or distribution according to environmental conditions or time of use. For example, light intensity and area of distribution may be reduced when pedestrians are not present. If LEDs are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions.
[0055]Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of this invention may be practiced in the absence of an element/step not specifically disclosed herein.