Uniformization of LED arrays

Abstract

Luminaires and LED light engines are provided. The luminaire includes the LED light engine and an optical device. The LED light engine includes an array of LEDs and a partial diffuser. The partial diffuser diffuses light emitted from LEDs in a first subset of LEDs selected from the array of LEDs and leaves undiffused light emitted from LEDs in a second subset of LEDs. At least some of the LEDs are selected for inclusion in the first subset to emit light that produces undesirable fused colors in a light beam emitted by the array of LEDs. The optical device is configured to receive a light beam emitted by the LED light engine and emit a modified light beam.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application 63 / 279,537, entitled “Uniformization of LED Arrays” by Jan Vilem et al., filed November 15, 2021, which is incorporated by reference as if fully copied herein. TECHNICAL FIELD

[0003] The present disclosure relates generally to light emitting diode (LED) luminaires, and more particularly to methods of uniformizing the output of a luminaire using a multi-emitter LED array. BACKGROUND

[0004] Luminaires with automatic and remote control functionality, referred to as automated luminaires, are well known in the entertainment and architectural lighting markets. Such products are commonly used in theaters, television studios, concerts, theme parks, nightclubs, and other venues. A typical automated luminaire provides control of the output intensity, color, and other functions of the luminaire from a remote location, thereby allowing an operator to control these functions of many luminaires simultaneously. Additionally or alternatively, many automated luminaires provide control of other parameters (e.g., the position, focus, zoom, beam size, beam shape, and / or beam pattern of a light beam emitted from the luminaire) from a remote location. SUMMARY

[0005] In a first embodiment, a light emitting diode (LED) light engine includes an array of LEDs and a partial diffuser. The partial diffuser is configured to diffuse light emitted from LEDs in a first subset of LEDs in the array of LEDs and leave un-diffused light emitted from LEDs in a second subset of LEDs in the array of LEDs.

[0006] In a second embodiment, a luminaire includes an LED light engine and an optical device. The light engine includes an array of LEDs and a partial diffuser. The partial diffuser is configured to diffuse light emitted from LEDs in a first subset of LEDs in the array of LEDs and leave un-diffused light emitted from LEDs in a second subset of LEDs in the array of LEDs. The optical device is configured to receive a light beam (including light emitted by the LED light engine) and emit a modified light beam. BRIEF DESCRIPTION OF DRAWINGS

[0007] For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings in which like reference numerals represent like features.

[0008] Figure 1 A schematic diagram of a luminaire system according to the present disclosure is shown.

[0009] Figure 2 An LED array is shown;

[0010] Figure 3 An example of a luminaire output of a luminaire having Figure 2 an LED array mounted is shown;

[0011] Figure 4 A region of the LED array of Figure 2 is shown in relation to a color band and / or striation in the luminaire output of Figure 3 ;

[0012] Figure 5 A view of an LED light engine having a partial diffuser mounted according to the present disclosure is shown;

[0013] Figure 6 An example of a luminaire output of a luminaire having Figure 5 an LED light engine and a partial diffuser mounted according to the present disclosure is shown;

[0014] Figure 7 A schematic view of a portion of the optical system of a luminaire without a partial diffuser is shown;

[0015] Figure 8 Overlap between beams of light from adjacent LEDs in the luminaire of Figure 7 is shown;

[0016] Figure 9 A schematic view of a portion of the optical system of a luminaire according to the present disclosure is shown;

[0017] Figure 10 An isometric view of the LED light engine of Figure 9 is shown;

[0018] Figure 11 A view of the LED array of Figure 2 as seen by the output of the zoom optical system in a wide angle configuration is shown;

[0019] Figure 12 A view of the LED array of Figure 2 as seen by the output lens of the zoom optical system in a narrow angle configuration is shown;

[0020] Figure 13 A view of the LED light engine of Figure 5 as seen by the output of the zoom optical system in a wide angle configuration is shown;

[0021] Figure 14 A view of the LED light engine of Figure 5A view of the LED light engine. DETAILED DESCRIPTION

[0022] Preferred embodiments are illustrated in the drawings, wherein like reference numbers refer to like and corresponding parts throughout the several views.

[0023] Figure 1 A schematic diagram of a luminaire system 10 according to the present disclosure is shown. The luminaire system 10 includes a plurality of luminaires 12 according to the present disclosure. Each luminaire 12 includes an onboard multi-emitter LED light source, a light modulation device, and can optionally include a pan and / or tilt system to control the orientation of the head of the luminaire 12.

[0024] In addition to being connected to the mains either directly or through a power distribution system, the control system of each luminaire 12 is also connected in series or in parallel to one or more consoles 15 through a data link 14. When an operator initiates, the console 15 sends a control signal via the data link 14, where the control signal is received by the control system of one or more luminaires 12. The control system of the one or more luminaires 12 that receive the control signal can respond by changing one or more parameters of the luminaire(s) 12 that received the signal. The control signal is sent by the console 15 to the luminaires 12 using DMX-512, Art-Net, ACN (Architecture for Control Networks), Streaming ACN, or other suitable communication protocol.

[0025] The luminaire 12 includes a light source that includes a multi-emitter LED light source, sometimes referred to as a light engine. The multi-emitter LED light source can include multiple groups of LEDs, where each group of LEDs emits a different color of light. In some embodiments, the colors used for the groups of LEDs can be red, green, blue, amber, and lime. In operation, an operator can control the relative intensities of the groups of LEDs, through the control system, in order to additively combine the output and adjust the color of the emitted light beam. For example, illuminating only the red and green LEDs will produce a yellow light beam, the blue and green will produce a cyan light beam, and so on. By controlling the relative intensities of the groups of LEDs, the operator can produce a wide variety of colors, including deep saturated colors, pastels, and a wide range of color temperatures of white.

[0026] It is desirable to mix and homogenize the light from the different color LEDs to produce a single color in the output light beam of the luminaire, with no or little color banding or striations in the homogenized light beam. Some luminaires have a lens or optical system that is intended to help with this homogenization. However, luminaires can also have adjustable zoom optical systems that enable the light beam to be adjusted from wide to narrow, and in combination with fast (wide aperture) lenses used to provide high output, such luminaires can still produce colored edges or striations in their output.

[0027] Figure 2A view of an LED array 200 is shown. The LED array 200 includes multiple LED emitters arranged in an array: five groups of LEDs, designated red 201, green 202, blue 203, amber 204, and stone gray 205. Each group of LEDs can be distributed and mixed throughout the LED array 200 to help homogenize the colors from all LEDs into a single-color output beam in later stages of the optical system. The approximately octagonal LED array 200 shown is merely exemplary. Arrays contemplated in this disclosure include arrays of any shape or size having any number of LED groups, where each group includes any number of LEDs.

[0028] Figure 3 It shows that it is installed Figure 2 An example of an illuminator output 300 of an LED array 200. The LED array 200 emits a light beam, which the illuminator projects as illuminator output 300: a nominal rectangular image with a soft focus. Although the center 301 of the illuminator output 300 blends well, evidence of imperfect or incomplete color uniformity is schematically shown at the bottom edge 302 and left edge 303 of the rectangular image, where color banding and stripes are visible. Reference Figure 4 The illuminator output 300 is further shown and described. Partly because the LEDs in the LED array 200 do not share a common optical axis, the illuminator output 300 is not a perfect uniformity and homogenization of the different colors in the LED array 200. References will follow below. Figure 4 discuss Figure 3 Other reasons for imperfect color uniformity, as illustrated in the diagram.

[0029] Figure 4 Showing Figure 2 The area of ​​the LED array 200 and Figure 3 The mapping between colored bands and / or stripes in the illuminator output 300. Undesirable effects in the beam emitted by the LED array 200 and projected by the illuminator into the illuminator output 300 are particularly evident in the light from LED groups located at the edges of the LED array 200, where some LEDs have no directly adjacent LEDs on one or more sides. Figure 4LED regions 206a, 206b, 206c, and 206d of LED array 200 are shown as emitting light that produces poor color blending in the respective output regions 207a, 207b, 207c, and 207d of luminaire output 300. Because each of LED regions 206a, 206b, 206c, and 206d is on the edge of LED array 200, there are no adjacent LEDs on at least one side of some of the LEDs in the region, which can be referred to as edge LEDs. As a result, the color blending of light from each LED region is non-uniform, and the respective output regions do not have the same color proportions as presented in the center of the array, resulting in color bands and / or streaks. In one example, the prevalence of red and blue LEDs in region 206a results in a magenta shift in the corresponding output region 207a. The other indicated LED regions have similarly unbalanced color proportions, resulting in color shifts in their respective output regions. Color blending in the output regions is improved by the partial diffuser of the present disclosure, as explained in more detail below.

[0030] In some luminaires, the non-uniform color mixing can be improved by individually controlling the light output intensity of the LEDs in the LED regions near the edges of LED array 200. For example, if a region has too many red and blue LEDs (compared to the other colors), as shown in Figure 4 the luminaire's controller can electrically dim the red and blue emitters in that region to reduce their output and correct the color mixing in the corresponding output region. In some such embodiments, the luminaire's controller can link such intensity changes for individual LEDs to the configuration of one or more optical devices of the luminaire. For example, when the zoom lens is in a wide-angle configuration (the light beam projected includes the edge LEDs), the controller can apply the intensity correction, and when the zoom lens is in a narrow-angle configuration (the light from the edge LEDs is not included in the projected light beam), the controller does not apply the correction. This is described in more detail below with reference to Figure 11 and Figure 12 This zoom lens is described in more detail below.

[0031] Figure 5 A view of an LED light engine 500 mounted with a partial diffuser 502 according to the present disclosure is shown. LED light engine 500 is suitable for use with the luminaire described with reference to Figure 1The one or more of the luminaire 12 described. The LED light engine includes an array of LEDs 501, mounted with a partial diffuser 502, indicated by diagonal shading. The partial diffuser 502 covers a first region of the array of LEDs 501, while a second region 503 of the array of LEDs 501 is not diffused by the partial diffuser 502. The partial diffuser 502 is referred to as a "partial" diffuser because it is configured to diffuse light emitted by LEDs in the first region, but leave undiffused light emitted by LEDs in the second region 503.

[0032] As Figure 5 indicated, the partial diffuser 502 covers LEDs, including at least some of the LED regions 206a, 206b, 206c, and 206d, as indicated. Figure 4 The selection of LEDs covered by the partial diffuser (in theory, empirically, or both) is intended to improve color blending in the projected light beam by reducing the number and intensity of output regions corresponding to projected light beams having color bands or striations or other undesirable blending of colors.

[0033] While the partial diffuser 502 covers LEDs primarily around the edges of the array of LEDs 501, in other embodiments, a partial diffuser according to the present disclosure can cover more or fewer LEDs than the partial diffuser 502 described, or can cover LEDs in other regions of the array of LEDs 501. The LEDs in the first region of the array of LEDs 501 are adjacent to one another. Thus, the first region can be said to be a contiguous region of LEDs. In other embodiments, the first region can include multiple non-contiguous regions of LEDs. Similarly, while the second region 503 of the array of LEDs 501 (not covered by the partial diffuser 502) is a contiguous region, in other embodiments, the second region 513 can include multiple non-contiguous regions.

[0034] While the partial diffuser 502 is shown in Figure 5 conformity with the edges of the LEDs in the first region, the first region is defined to include all LEDs that are covered, in whole or in part, by the partial diffuser 502. Thus, the first region includes a selected first subset of LEDs of the array of LEDs 501 that are covered, in whole or in part, by the partial diffuser 502. The second region 503 is complementary to the first region, including a second subset of LEDs that are all of the LEDs of the array of LEDs 501 that are not included in the first subset.

[0035] In some embodiments, the partial diffuser 502 comprises a material such as frosted glass or a frosted polymer. In other embodiments, the partial diffuser 502 comprises a thin film coating (e.g., titanium dioxide or other material) on the surface of an existing or additional optical element of the LED light engine 500 or illuminator 12. In still other embodiments, the partial diffuser 502 may comprise other suitable materials for providing light diffusion. In some embodiments, the partial diffuser 502 is manufactured as a diffuser covering all LEDs in the LED array 501, and a portion of the diffusing material is subsequently removed by cutting, ablation, or other removal techniques to form a second region 503. This manufacturing and removal may be performed on existing optical elements of the LED light engine 500 or illuminator 12, or on separate elements added to the LED light engine 500 or illuminator 12. In still other embodiments, the partial diffuser 502 may comprise individual sheets of diffusing material.

[0036] Figure 6 An example of a luminaire output 600 according to this disclosure is shown, the luminaire being equipped with Figure 5 The LED light engine 500 and partial diffuser 502. In the example shown in the figure, the illuminator projects light with... Figure 3 The image shown is the same nominal rectangular image, with soft focus. The center 601 of the illuminator output 600 blends well, and (for example) the bottom edge 602 and left edge 603 are better at homogenization (reduction in the size and color saturation of the striped areas) than... Figure 3 The significant improvement shown.

[0037] Figure 7 A schematic diagram shows a portion of the optical system of an illuminator 700 without a partial diffuser. The illuminator 700 includes... Figure 2 The LED array 200. Light from the LED array 200 passes through the beam homogenization optics 701 and the condenser lens 702, is guided to the imaging plane 703, and then, as a beam 704, is directed downstream towards the projection optics. Figure 7 (Not shown in the image) is emitted.

[0038] Figure 8 Showing Figure 7 The overlap between beams from adjacent LEDs in the illuminator 700. For example, a beam 705 from a first LED and a beam 706 from an adjacent second LED (two LEDs from the LED array 200) are shown. These two beams 705 and 706 overlap in region 707 passing through the beam homogenization optics 701.

[0039] Figure 9A schematic diagram of a portion of the optical system of an illuminator 900 according to this disclosure is shown. The illuminator 900 may include a fixedly mounted device, a reference... Figure 1 The described illuminator 12 has a panning / tilting head, or a light engine for a moving mirror device. Illuminator 900 includes... Figure 5 and Figure 10 The LED light engine 500 emits a light beam that passes through optical devices such as a beam homogenization optics 901, a condenser lens 902, and an imaging plane 903, and then exits the imaging plane 903 as a beam 904 and passes through a projection optics, a zoom lens, and / or other optical devices (e.g., lenses, light shields, irises, or prisms). Figure 9 (not shown in the image) is emitted from illuminator 900 as an illuminator beam. In various embodiments, the light engine beam emitted by LED light engine 500 can be compared with a reference beam before being emitted as a modified beam. Figure 9 The more, fewer, or different optical devices shown and described.

[0040] Figure 9 The image also shows the overlap between beams from adjacent LEDs in the first region of LED array 501 (covered by partial diffuser 502). The figure shows beam 908 from the first LED and beam 909 from an adjacent second LED (both LEDs are located in the first region of LED light engine 500). These two beams (which have passed through the partial diffuser 502) are more... Figure 8 The beams 705 and 706 are wider, resulting in an overlap area 910 greater than... Figure 8 The overlapping region 707 shown is much larger. The larger overlapping region 900 entering the beam homogenization optics 901 improves beam uniformity. Region 911 represents light loss that has been diffused beyond the edge 912 of the optical system.

[0041] Figure 10 Showing Figure 9 An elevation view of an LED light engine 500. According to this disclosure, the LED light engine includes an array of LEDs 522 and associated light engine optics. The LEDs 522 are mounted on a substrate 521. Light from the LEDs 522 passes through a first lens array 523, a second lens array 524, and a partial diffuser 502. Figure 10 In the illustrated embodiment, the partial diffuser 502 is an optical element located in the beam emitted by the LED 522, following the second lens array 524. In other embodiments, the partial diffuser 502 may be an optical element in the beam emitted by the LED 522, located between the LED 522 and the first lens array 523, or between the first lens array 513 and the second lens array 524.

[0042] In some embodiments, a partial diffuser 502 can be applied as a coating to the optical surface of any of these components, including but not limited to the front (light-emitting) surface of the LEDs 522, the front or back surface of the first lens array 523, or the front or back surface of the second lens array 524. As used herein, the back surface of a lens is the surface that receives light, and the front surface of a lens is the surface that emits light.

[0043] Either of the luminaires 700 or 900 can include a zoom optical system. When the zoom optical system is configured to project a wide-angle beam of light, all of the light emitted by its light source (e.g., the LED array 200 or the LED light engine 500) enters the zoom optical system and is emitted from the zoom optical system. However, when the zoom optical system is configured to project a narrow-angle beam of light, all of the light emitted by the light source still enters the zoom optical system, but only the light emitted by the central region of the light source is emitted from the zoom optical system. Thus, it can be said that the “field of view” of the zoom optical system or the “field of view” of the light source changes as the beam angle is adjusted. Similarly, the central region of the light source can be said to be the only portion of the light source that is “seen” or “visible” to the output lens of the zoom optical system.

[0044] Figure 11 A view of the LED array 200 as seen by the output of the zoom optical system in a wide-angle configuration is shown. The entire LED array 200 is visible in the output of the zoom optical system. However, when the zoom optical system is in a narrow-angle configuration, the field of view of the array can be vignetted, resulting in only the central portion of the LED array 200 being visible. Figure 12 A view of the LED array 200 as seen by the output lens of the zoom optical system in a narrow-angle configuration is shown. The LEDs between the outer edge 1202 of the LED array 200 and the vignetting edge 1204 are not visible to the output lens. As a result, as the zoom optical system is moved between the wide-angle and narrow-angle configurations, the mix (or proportion) of different colored LEDs in the projected beam of light can change, resulting in varying amounts and intensities of color variation and / or colored bands and streaks in the projected beam of light.

[0045] In a similar manner, Figure 13 and 14 A field of view of the LED light engine 500, including the partial diffuser 502, is shown. Figure 13 A view of the LED light engine 500 as seen by the output of the zoom optical system in a wide-angle configuration is shown. Figure 14 A view of the LED light engine 500 as seen by the output lens of the zoom optical system in a narrow-angle configuration is shown. The LEDs located between the outer edge 1402 of the LED light engine 500 and the vignetting edge 1404 are not visible to the output lens.

[0046] InFigure 13 and Figure 14 In the embodiment shown in FIG. 14A, the diffusion applied by the partial diffuser 502 to the LEDs in the first region of the LED array 501 is fully visible to the output of the zoom optical system in the wide-angle configuration (as shown in FIG. 14B). When the zoom optical system is in the narrow-angle configuration, fewer of the LEDs in the first region of the LED array 501 are visible to the lens (as shown in FIG. 14C). However, some of the light from the LEDs in the first region between the outer edge 1402 and the vignetting edge 1404 is spread by the partial diffuser 502 toward the center of the beam, which results in the mixing (or proportion) of different colors of the LED array 501 remaining closer to constant in the homogenized beam as the zoom lens moves between the wide-angle and narrow-angle configurations, providing reduced color variation. Figure 13 Figure 14 As described with reference to FIG. 14A, the partial diffuser 502 covers a first subset of LEDs of the LED array 501, where the first subset of LEDs is selected to improve color blending in the beam projected by the luminaire 1400. As shown in FIG. 14D, some of the LEDs in the first subset can be selected to improve color blending in the beam projected when the zoom optical system is in the narrow-angle configuration.

[0047] As described with reference to FIG. 14A, the partial diffuser 502 covers a first subset of LEDs of the LED array 501, where the first subset of LEDs is selected to improve color blending in the beam projected by the luminaire 1400. As shown in FIG. 14D, some of the LEDs in the first subset can be selected to improve color blending in the beam projected when the zoom optical system is in the narrow-angle configuration. Figure 5 Figure 14

[0048] While only some embodiments of the present disclosure have been described herein, those skilled in the art who have the benefit of this disclosure will appreciate that other embodiments can be made without departing from the scope of the present disclosure. Accordingly, many modifications can be made by those skilled in the art without departing from the spirit and scope of the present disclosure.​​​

Claims

1. A light-emitting diode (LED) light engine, comprising: An LED array, the LED array comprising multiple groups of LEDs of different colors, wherein each group of LEDs emits light with a characteristic color, and the characteristic color of each color group is different from the characteristic colors of the other color groups; and A partial diffuser is configured to diffuse light emitted from LEDs in a selected first subgroup of LEDs in the LED array and leave undiffused light emitted from LEDs in a second subgroup of LEDs in the LED array, wherein the first subgroup of LEDs comprises LEDs with a first proportion of color groups, and the second subgroup of LEDs comprises LEDs with a second proportion of color groups, the first proportion being different from the second proportion.

2. The LED light engine of claim 1, wherein at least some of the LEDs in the LED array are selected to be included in the first subgroup, emitting an undiffuse beam that produces colored bands or stripes in the beam emitted by the LED array.

3. The LED light engine of claim 1, wherein the partial diffuser comprises a first optical element located in the light beam emitted by the LED array.

4. The LED light engine of claim 1, wherein the partial diffuser comprises a diffuser material applied to the surface of a second optical element of the LED light engine.

5. The LED light engine of claim 4, wherein the second optical element comprises a lens array, and the partial diffuser comprises a thin film layer on the front surface of the lens array.

6. The LED light engine of claim 1, wherein the LEDs of the first subgroup are adjacent to each other.

7. A lighting device, comprising: The light engine according to any one of claims 1 to 6; as well as An optical device configured to receive a light beam emitted by the light engine and to emit a modified light beam.

8. The illuminator of claim 7, further comprising a zoom optical system configured to receive the modified light beam, wherein when the zoom optical system is in a narrow-angle configuration, at least some of the LEDs in the first subgroup of LEDs are visible to the output lens of the zoom optical system.

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