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EP-4736580-A1 - LED LUMINANCE TUNING TO ADJUST ILLUMINATION DISTRIBUTION

EP4736580A1EP 4736580 A1EP4736580 A1EP 4736580A1EP-4736580-A1

Abstract

A light emitting diode (LED) array, illumination device, and method of operating the LED array are described. The illumination device includes the LED array with LEDs. Drivers drive different sets of the LEDs. Each driver drives the LEDs of an associated set in parallel to produce light. The light from at least one of the LEDs has a different radiance from the light from at least one other of the LEDs. A processor controls the drivers to drive the sets of LEDs via driver channels to achieve a targeted illumination from the LED array. The radiance is varied using different reflectors, tile resistances, and/or eVias having different diameters and/or spatial densities.

Inventors

  • BARTON, PHILLIP
  • DIMARIA, JEFFREY VINCENT
  • VAN DER SIJDE, ARJEN GERBEN
  • WONG, Hung Khin
  • YOUNG, ERIK WILLIAM
  • PFEFFER, NICOLA BETTINA

Assignees

  • Lumileds LLC

Dates

Publication Date
20260506
Application Date
20240612

Claims (20)

  1. 1. An illumination device comprising: a light emitting diode (LED) array comprising segmented LEDs; a plurality of drivers configured to drive different sets of the segmented LEDs, each of the plurality of drivers configured to drive the segmented LEDs of an associated set of the segmented LEDs in parallel to produce light, the light from at least one of the segmented LEDs of the associated set of the segmented LEDs having a different radiance from the light from at least one other of the segmented LEDs of the associated set of segmented LEDs; and a processor configured to control the drivers to drive the sets of segmented LEDs via driver channels to achieve a targeted illumination from the LED array.
  2. 2. The illumination device of claim 1, wherein the sets of the segmented LEDs are dependent on a number of the driver channels.
  3. 3. The illumination device of claim 1 or 2, wherein: the LED array is rectangular, and the sets of the segmented LEDs are concentric rings around a center.
  4. 4. The illumination device of any of claims 1-3, further comprising one or more optical elements configured to adjust light from the LED array, wherein: the one or more optical elements have a different shape than the LED array, the light from the sets of segmented LEDs is dependent on the shapes of the one or more optical elements and the LED array, and the drivers are configured to drive the sets of segmented LEDs dependent on the shapes of the one or more optical elements and the LED array.
  5. 5. The illumination device of any of claims 1-4, wherein each of the segmented LEDs comprises a reflector configured to reflect light from the segmented LED towards an exit surface of the segmented LED, reflectivity of the reflector of the at least one of the segmented LEDs of the associated set of the segmented LEDs being different from reflectivity of the reflector of the at least one other of the segmented LEDs of the associated set of segmented LEDs.
  6. 6. The illumination device of any of claims 1-5, further comprising a tile through which the segmented LEDs are electrically coupled to the driver, the tile providing different resistances to couple the at least one of the segmented LEDs of the associated set of the segmented LEDs to the driver than the at least one other of the segmented LEDs of the associated set of segmented LEDs to the driver.
  7. 7. The illumination device of any of claims 1-6, wherein the LED array further comprises: semiconductor layers comprising an active layer configured to generate the light; a Transparent Conductive Oxide (TCO) layer disposed on the semiconductor layers; a dielectric spacer disposed on the TCO layer; a mirror disposed on the dielectric spacer, the mirror configured to reflect the light toward an exit surface of the LED array; and eVias of each segmented LED to electrically couple the TCO layer to the mirror, at least one characteristic of the e Vias of the at least one of the segmented LEDs of the associated set of the segmented LEDs being different than at least one characteristic of the eVias of the at least one other of the segmented LEDs of the associated set of segmented LEDs.
  8. 8. The illumination device of claim 7, wherein the at least one characteristic of the eVias comprises a diameter of the eVias.
  9. 9. The illumination device of claim 7, wherein the at least one characteristic of the eVias comprises a spatial density of the eVias.
  10. 10. The illumination device of any of claims 1-9, further comprising one or more optical elements configured to adjust light from the LED array, the one or more optical elements having a different shape than the LED array, the drivers configured to provide a predetermined current distribution dependent on a field of view of a camera in which the illumination device is incorporated.
  11. 11. The illumination device of any of claims 1-10, wherein: in each segmented LED, nVias couple an n bonding layer to an n-type semiconductor of the segmented LED, and at least one characteristic of the nVias of at least one of the segmented LEDs is different than the at least one characteristic of the nVias of at least one other of the segmented LEDs.
  12. 12. The illumination device of claim 11, wherein the at least one characteristic of the nVias comprises a diameter of the nVias.
  13. 13. The illumination device of claim 11, wherein the at least one characteristic of the nVias comprises a spatial density of the nVias.
  14. 14. The illumination device of any of claims 1-13, wherein: each segmented LED contains: semiconductor layers that include an active layer configured to generate the light; and a Transparent Conductive Oxide (TCO) layer disposed on the semiconductor layers, and at least one characteristic of the TCO layer of at least one of the segmented LEDs is different than the at least one characteristic of the TCO layer of at least one other of the segmented LEDs.
  15. 15. The illumination device of claim 14, wherein the at least one characteristic is selected from a group of characteristics that include uniform thickness over a substantial entirety of the TCO layer and diameter and density of regions of different thicknesses of the TCO layer.
  16. 16. The illumination device of any of claims 1-15, wherein at least one characteristic is different between pixel segments on a same driver channel, the at least one characteristic selected from a group of characteristics that include: diameter and density of n-edge contacts, diameter and density of nVias that couple an n bonding layer to an n-type semiconductor of the semiconductor layers, and uniform thickness over a substantial entirety of a Transparent Conductive Oxide (TCO) layer disposed on the n-type semiconductor, or diameter and density of regions of different thicknesses of the TCO layer.
  17. 17. A light emitting diode (LED) array comprising a plurality of segmented LEDs, each of the plurality of segmented LEDs comprising: semiconductor layers comprising an active layer configured to generate light; a Transparent Conductive Oxide (TCO) layer disposed on the semiconductor layers; a dielectric spacer disposed on the TCO layer; a mirror disposed on the dielectric spacer, the mirror configured to reflect the light toward an exit surface of the LED array; and eVias electrically coupling the TCO layer to the mirror, the segmented LEDs being separated into sets of segmented LEDs that are driven in parallel to produce the light, the light from at least one of the segmented LEDs of an associated set of the segmented LEDs having a different radiance from the light from at least one other of the segmented LEDs of the associated set of segmented LEDs.
  18. 18. The LED array of claim 17, wherein a tile through which the segmented LEDs are electrically coupled to a driver is to provide different resistances to couple the at least one of the segmented LEDs of the associated set of the segmented LEDs to the driver than the at least one other of the segmented LEDs of the associated set of segmented LEDs to the driver.
  19. 19. A method of producing light from an illumination device, the method comprising driving sets of segmented light emitting diodes (LEDs) of an LED array to produce a targeted illumination, the segmented LEDs of an associated set of the segmented LEDs being driven in parallel to produce light, the light from at least one of the segmented LEDs of the associated set of the segmented LEDs has a different radiance from the light from at least one other of the segmented LEDs of the associated set of segmented LEDs.
  20. 20. The method of claim 19, wherein the sets of the segmented LEDs include concentric rings around a center pixel.

Description

LED LUMINANCE TUNING TO ADJUST ILLUMINATION DISTRIBUTION PRIORITY CLAIM [0001] This application claims the benefit of priority to United States Provisional Patent Application Serial No. 63/523,459, filed June 27, 2023, which is incorporated herein by reference in its entirety. FIELD OF THE DISCLOSURE [0002] The present disclosure relates to light emitting diode (LED) arrays. In particular, embodiments are directed to adjusting illumination provided by LED arrays. BACKGROUND OF THE DISCLOSURE [0003] LED arrays are used in a wide variety of applications. In certain applications, the distribution of the illumination from the LED arrays is of little importance. In other embodiments, such as illumination for used to obtain images, it may be desirable to provide illumination having a predetermined distribution. Attaining a desired distribution may be dependent on a number of factors, including limitations on components within the device providing the illumination. BRIEF DESCRIPTION OF THE DRAWINGS [0004] FIG. 1 shows an example illumination apparatus, in accordance with some examples. [0005] FIG. 2 illustrates an example of a general device in accordance with some embodiments. [0006] FIG. 3 illustrates an example LED array, in accordance with some examples. [0007] FIG. 4A illustrates a cross-section of an LED in an LED array, in accordance with some examples. [0008] FIG. 4B illustrates a cross-section of another LED in an LED array, in accordance with some examples. [0009] FIG. 4C illustrates a cross-section of another LED in an LED array, in accordance with some examples. [0010] FIG. 5 illustrates a cross-sectional view of a single-die package architecture, in accordance with some examples. [0011] FIGS. 6A and 6B illustrate illumination without and with flux compensation in accordance with some embodiments. [0012] FIG. 7 illustrates an example lighting system, according to some embodiments. [0013] FIG. 8 illustrates an example lighting device, according to some embodiments. [0014] FIG. 9 shows a block diagram of an example of a system, according to some embodiments. [0015] FIG. 10 illustrates an example method of fabricating an illumination device, according to some embodiments. [0016] FIG. 11 illustrates a top plan view of an example array suitable for implementing embodiments described herein. DETAILED DESCRIPTION [0017] The illumination distribution of segmented LEDs may be controlled in various ways. Illumination as used herein may include visible illumination, infrared illumination, and/or ultraviolet (UV) illumination, and may be used in a variety of applications, for example in time-of-flight applications or for adaptive UV for industrial UV curing. In particular, adaptive flash may use segmented LEDs and a near-imaging lens to control the illuminance distribution of a target area (“scene”); that is, segmented emitters with one or more optical elements may be used to realize steerable illumination (either with or without mechanically adjusting the position of the segmented LEDs). By selectively illuminating specific segments, the scene is also selectively illuminated in those areas corresponding to the activated segments. Ideally, the current of each segment is individually set; individual segments can be switched on or off or tuned with different currents between segments such that the scene is illuminated selectively, with an illumination distribution proportional to the applied current density distribution. [0018] However, as the number of segments of the emitter increases (i.e., the higher the resolution of the MxN matrix forming the emitter), the greater the number of channels used for the driver(s). Moreover, hardware (and perhaps spatial) limitations may exist that limit increasing the number of drivers, limiting the number of channels to significantly fewer than the MxN elements, e.g., (N+l)/2 in some embodiments. A large number of current drivers (MxN) may result in an integration of the driver with the emitter. If, however, integration does not occur, choices for tunability may be employed. Such choices may result in, for example, only a variable beam collimation being implemented. In this case, several segments may be grouped together and fewer than one current source used per segment. In the above MxN rectangular array for example, the center segment may be driven by a first channel, adjacent segments may be driven together as a ring for a second channel, and similarly continuing outwards, groups of segments forming rings of driven together. Each channel thus drives the segments grouped together in parallel (which may be, as above, concentric rings around a center pixel), with the flux density per segment being equal to the current density and the segments of the channel emitting close to or substantially equal brightness or radiance. [0019] In addition to the tunability, the shape of the target area may be taken into account. For adaptive flash applications, the array may be incorporated