LED luminaire with optical element

Abstract

An LED luminaire comprising an LED array of LED elements and an optical element. The optical element comprises one or more partially reflective or partially transmissive elements positioned normal to the plane of the LED array. In this way, the partially reflective elements create virtual sources or virtual LED elements by reflecting a portion of the light emitted by the LED elements, while allowing the original or "real" LED elements to remain visible by partially transmitting the light.

Description

Technical Field

[0001] This disclosure relates to the field of LED luminaires, and more particularly to an LED luminaire with additional optical elements. Background Technology

[0002] LED luminaires are increasingly being used in commercial lighting installations, such as road lighting and industrial lighting. In these cases, LED luminaires typically consist of an array of LED elements, each formed by a visible light LED and a corresponding lens.

[0003] This optical architecture is particularly advantageous in commercial lighting installations because of their high energy efficiency. However, using a separate lens for each LED results in LED luminaires with increased glare, for example, compared to a single uniform light source of the same size as the array.

[0004] Therefore, it is desirable to provide an LED luminaire that offers the benefit of reduced glare without lower energy efficiency.

[0005] One possible approach is to reduce the pitch of the LED array, that is, to reduce the distance between the individual LED elements in the array. A smaller pitch means the human eye is less able to distinguish individual LED elements, resulting in more uniform and less glaring light emitted by the illuminator. However, as the number of LED elements increases twice, reducing the pitch of the LED array leads to higher costs. The size of the lenses also needs to be reduced, making them more difficult to manufacture. Summary of the Invention

[0006] This invention is defined by the claims.

[0007] According to an example of one aspect of the invention, an LED illuminator is provided, comprising: an array of LED elements, each LED element configured to emit light, disposed in a first plane; and an optical element comprising one or more partially reflective elements, each partially reflective element positioned to directly receive light emitted by the LED elements of the array of LED elements and including a light incident surface positioned perpendicular to the first plane, wherein each partially reflective element is configured to reflect a first portion of the received light using at least the light incident surface and transmit a second different portion of the received light, and wherein at least one partially reflective element is positioned such that a virtual source of the first portion of the directly received light reflected using the light incident surface is located between the LED element from which the partially reflective element directly receives light and adjacent LED elements.

[0008] This disclosure uses one or more partially reflective elements to effectively separate light emitted by an LED element, such that a first (reflected) portion of the light emitted by the LED element appears to originate from a virtual source located on the side of the LED element, and a second (transmitted) portion of the light emitted by the LED element appears to originate from the LED element itself.

[0009] This results in a reduction in the effective pitch of the LED element array by creating one or more virtual sources (virtual LED elements) between the (real) LED elements, without providing additional LED elements in the array. Therefore, the light emitted by a particular LED element appears to be redistributed at least partially across the real LED elements and at least one virtual LED element, thereby reducing the apparent brightness of any single LED element (with minimal impact on the total value of light output by the LED illuminator), thus softening the appearance of the LED illuminator and reducing noticeable glare.

[0010] In addition, existing LED panels and lens panels can be reused, thereby minimizing costs for end users.

[0011] A partial reflective element includes a light-incident surface that reflects at least some of the directly received light, thus contributing to light reflection performed by the partial reflective element. Therefore, the light-incident surface acts as an interface for reflecting light. A partial reflective element may include one or more other interfaces for reflecting the received light, i.e., a first portion of the light that contributes to reflection.

[0012] Positioning the light-incident surface for reflecting light perpendicular to the first plane causes light reflected from at least the light-incident surface to appear to originate from the same dummy LED element, thereby reducing the apparent or effective spacing of the LED array. This method also implies that the reflected and transmitted portions of the beam are guided away from the first plane to maintain the total amount of light output from the LED illuminator (assuming scattering and absorption are negligible). The proposed method avoids light (previously already output by the LED illuminator) being reflected back into the LED array.

[0013] Preferably, the light incident surface is a substantially flat and / or smooth surface region (i.e., a smooth surface) to increase the apparent brightness uniformity of the LED illuminator and reduce deviations from the original luminous intensity distribution. A flat surface region helps prevent the surface from deviating from the vertical plane of symmetry. An (optically) smooth surface reduces scattering, making reflections and / or transmissions specular or near-specular.

[0014] At least one partially reflective element is disposed between two adjacent LED elements in the array of LED elements, such that a virtual source of light, which is directly received from one of the two elements and has been reflected by at least a light-incident surface, is located between the two adjacent LED elements. This increases the apparent positional uniformity (e.g., distribution) of the real and virtual LED elements, as well as the brightness uniformity of the light output from them. Preferably, at least one partially reflective element is disposed between two adjacent LED elements such that the virtual source is located (approximately) in the middle between the two adjacent LED elements.

[0015] In some embodiments, each LED element of the array of LED elements is configured to emit light with a luminous intensity distribution having at least one mirror-symmetric plane, and the light-incident surface of each partially reflective element is positioned parallel to one or more luminous intensity distributions of the LED element from which each partially reflective element directly receives light. Arranging the light-incident surface of each partially reflective element parallel to the mirror-symmetric plane causes the virtual source to appear to have a partially luminous intensity distribution symmetrical to a portion of the luminous intensity distribution of the LED element from which each partially reflective element directly receives light. This increases the uniformity of the luminous intensity output on the LED illuminator, which is perceived by the observer relative to a particular viewing direction and reduces glare. In particular, this method makes all sources (real and virtual) appear to have more uniform brightness across a range of viewing directions.

[0016] Preferably, the optical element is configured such that, for each partial reflective element, the first light output by the LED illuminator that is last reflected by the partial reflective element has a corresponding second light output by the illuminator, the second light being last reflected by another partial reflective element, the corresponding second light having mirror symmetry with respect to the first light with respect to a plane of symmetry parallel to the partial reflective element.

[0017] In other words, each of the multiple light rays (which have already been reflected by any partial reflective element) or multiple reflected light rays can be one of the reflected light rays from a group of two reflected light rays (which have already been reflected by any partial reflective element) output by the LED illuminator. The first light ray in the group of two light rays has mirror symmetry with respect to the plane of symmetry of the partial reflective element that was last reflected by the first light ray (before the group of light rays output by the illuminator).

[0018] Preferably, each of the plurality of reflected rays may have its own unique corresponding mirror-reflected ray.

[0019] Multiple light rays may include at least 90%, for example at least 95%, or for example at least 99%, of all light rays output by the LED illuminator that have already been reflected by the partially reflective elements.

[0020] Compared to LED illuminators that do not include this optical element, this configuration results in an unchanged overall luminous intensity distribution of the LED illuminator (within a reasonable margin of error, such as ±10% or ±1%), but with improved apparent brightness uniformity.

[0021] This configuration can be achieved through proper positioning and arrangement of some reflective elements.

[0022] Specifically, the partial reflective elements can be arranged such that each combination of an LED element and a partial reflective element (which reflects the light emitted by the LED element) corresponds to another combination of another LED element and another partial reflective element that reflects the light emitted by the other LED element. The light reflected by the other partial reflective element (received from the other LED element) is a mirror image of the light reflected by the original partial reflective element (received from the original LED element).

[0023] For example, this configuration can be achieved by shaping each partial reflective element into one of two partial reflective elements (which form a group of two partial reflective elements). The two partial reflective elements in the group are positioned parallel to each other, and preferably positioned (and the LED array is appropriately configured) such that the light reflected by the first partial reflective element is a mirror image of the light reflected by the second partial reflective element.

[0024] This can be achieved by positioning a first reflective element on one side of an LED element and a second reflective element on the opposite side of an LED element (which can be the same LED element or different LED elements with the same light intensity distribution). The distance between the first reflective element and its corresponding LED element can be the same as the distance between the second reflective element and its corresponding LED element. Except for their positions, the first and second reflective elements can be identical (within reasonable manufacturing tolerances).

[0025] If each partial reflective element is formed in this way (i.e., forming part of a group that meets these requirements), the overall luminous intensity distribution of the LED illuminator remains unchanged (within a reasonable margin of error, such as ±10% ±1%) compared to an LED illuminator that does not include this optical element, but with improved apparent brightness uniformity.

[0026] Preferably, the first and second partial reflective elements in the group of partial reflective elements are positioned such that at least some of the light reflected by the first partial reflective element appears to originate from the same virtual source as some of the light reflected by the second partial reflective element. This helps the virtual sources appear to have a light distribution similar to that of a real LED element. This method makes all sources (real and virtual) appear to have more uniform brightness across the range of viewing directions.

[0027] Preferably, the luminous intensity distribution of the light emitted by each (individual) LED element is the same. This increases the uniformity of the luminous intensity output on the LED illuminator, which is perceived by the observer relative to a specific viewing direction and reduces glare.

[0028] In some embodiments, the luminous intensity distribution of light emitted by each LED element in the array of LED elements has a finite number of mirror-symmetric planes.

[0029] Preferably, the distance between each partial reflective element and its directly light-receiving LED element is between 0.1 and 0.4 times the distance between its directly light-receiving LED element and its adjacent LED element.

[0030] This distance can be defined as the distance along the first plane, that is, the distance between the LED element and the partially reflective element relative to the projection of the first plane. As an example, the first plane can define a horizontal plane, and this distance can be defined as the horizontal distance between the partially reflective element and the LED element that directly receives light.

[0031] The inventors have realized that positioning each part of the reflective element in this way produces an LED illuminator with improved brightness uniformity.

[0032] Preferably, the distance between each partial reflective element and its directly receiving LED element is between 0.2 and 0.3 times the distance between its directly receiving LED element and its adjacent LED element.

[0033] In some preferred embodiments, the distance between each partial reflective element and its directly receiving LED element is different for each partial reflective element (and its corresponding LED element). In other words, there may be a slight randomization in the positioning of different partial reflective elements relative to their respective LED elements. This embodiment improves the uniformity of the apparent brightness of the light provided by the LED illuminator.

[0034] The distance between each partial reflective element and its directly receiving LED element can differ by no more than 20% of the distance between adjacent LED elements, for example, no more than 4% of the distance between adjacent LED elements. For example, if the LED elements are positioned 25 mm apart, the distance between each partial reflective element and its directly receiving LED element can differ by no more than 5 mm, for example, no more than 1 mm.

[0035] In a specific example, the horizontal position (i.e., the position relative to the first plane) of each partial reflective element is positioned to intersect with an imaginary line that passes through the LED element from which the partial reflective element directly receives light and adjacent LED elements at the intersection point. The distance between this intersection point and the LED element from which the partial reflective element directly receives light can define the distance between the partial reflective element and the LED element.

[0036] Preferably, the thickness of each partial reflective element is no greater than 1 mm, more preferably no greater than 0.8 mm, and most preferably no greater than 0.5 mm. For example, the thickness of each partial reflective element can be 0.5 mm. The inventors have noted that the thickness and shape of the element can affect the performance of the optical element, for example, because the edges of the element can cause undesirable beam artifacts. Thinner partial reflective elements provide better optical performance at the cost of ease of manufacture. The maximum thickness of 1 mm, 0.8 mm, and / or 0.5 mm provides a reasonable trade-off between optical performance and manufacturability.

[0037] Preferably, the edge rounding of each partial reflective element is no more than 0.3 mm, and more preferably no more than 0.2 mm, and even more preferably no more than 0.1 mm. This characteristic (edge ​​rounding) provides a reasonable trade-off between performance and manufacturability. The edge rounding is defined as the radius of the transition region between one side and the other side of the partial reflective element, located at the end of the partial reflective element, and particularly at the end of the partial reflective element opposite to the first plane (i.e., furthest from the first plane).

[0038] Preferably, at least one partially reflective element is configured to further receive a (reflected) first portion and / or (transmitted) second portion of light directly received by at least one other partially reflective element, and is also configured to partially reflect and partially transmit the received first portion and / or second portion of light.

[0039] In other words, light transmitted / reflected by one partially reflective element can interact with another partially reflective element (and be further partially reflected and transmitted). This creates an optical element in which light has multiple interactions with it. This embodiment further increases the uniformity of brightness distribution by creating additional virtual sources (e.g., outside the boundaries of the LED array).

[0040] This embodiment also reduces the need for high reflectivity in the partial reflective element, since alternatively, this embodiment relies on multiple Fresnel reflections (from interactions with multiple partial reflective elements) to achieve the same uniform effect as using a single partial reflective element with high reflectivity (e.g., >40% and <60%). Therefore, partial reflective elements with relatively low reflectivity (e.g., <40% or <30%) can be used.

[0041] Preferably, the length of at least one partially reflective element in the direction perpendicular to the first plane is not less than 0.4 times the distance between the LED element that directly receives light and the adjacent LED element, and preferably not less than 1 times that distance.

[0042] This embodiment can result in some of the reflective elements being long enough that the light reflected / transmitted by one of the reflective elements can further interact with another reflective element to achieve the same benefits as previously described (improved brightness uniformity, less dependent on interaction with a single reflective element).

[0043] It should be understood that in such embodiments, partially reflective elements closer to the edges of the LED array may have less interaction with light than partially reflective elements located at the center / middle of the illuminator. In some embodiments, partially reflective elements closer to the edges of the LED array may have a higher reflectivity than partially reflective elements located at the center / middle of the LED array. This further improves the brightness uniformity of the LED illuminator, particularly by increasing the apparent brightness uniformity of the dummy LED elements on the LED array.

[0044] Similarly, light rays emanating at a larger angle relative to the normal direction of the LED array (i.e., the direction perpendicular to the first plane) will interact with more of the partially reflective elements compared to light rays emitted closer to the normal direction. Therefore, it is advantageous for at least one partially reflective element to have greater reflectivity at a location farther from the first plane (compared to a location closer to the first plane). As an example, the partially reflective element can have a gradient of reflectivity relative to its distance from the first plane or the LED array, resulting in higher reflectivity at the far end of the board and lower reflectivity closer to the PCB. This gradient can be a gradual gradient or a stepped gradient. Such an embodiment will result in improved uniformity of brightness of the light emitted by the LED illuminator, achieved by increasing the similarity of the luminous intensity output by the dummy LED elements on the LED array.

[0045] In this embodiment, the first and / or second portion of the received light comprises not less than 25% and not more than 75% of the received light. In other words, the first portion of light / the second portion of light may comprise 25%-75% of the received light.

[0046] Preferably, the first or second portion of the received light comprises not less than 40% and not more than 60% of the received light. Even more preferably, the first or second portion of the received light comprises not less than 45% and not more than 55% of the received light. More preferably, the first or second portion of the received light comprises not less than 48% and not more than 52% of the received light. For example, the first portion of the received light may consist of about 50% (±1% or ±0.5%) of the received light, and / or the second portion of the received light may consist of about 50% (±1% or ±0.5%) of the received light.

[0047] It has been confirmed that the angle of incidence of light can affect the amount of light reflected by the partial reflective element. The percentages mentioned above refer to the average amount of light emitted by a particular LED element and received by the transmission / reflection partial reflective element.

[0048] The more similar the percentages of reflected and transmitted light, the higher the apparent uniformity of the brightness distribution (i.e., the greater the reduction in noticeable glare).

[0049] In some embodiments, a first portion of the received light comprises at least 75% of the received light having wavelengths within a first set of wavelengths; and a second portion of the received light comprises at least 75% of the received light having wavelengths within a different second set of wavelengths. In other words, the received light may be divided according to chromaticity such that the first set of wavelengths (most) is transmitted, while wavelengths from different sets (most) are reflected.

[0050] In some examples, each partial reflective element is configured such that, in the case where the received light comprises multiple rays, each ray is partially transmitted and partially reflected by the partial reflective element.

[0051] In other words, each ray of light received by the partially reflective element can be partially reflected and partially transmitted. In sub-embodiments suitable for providing this embodiment, any reference to "the portion that receives light" in any other embodiment described herein may be replaced by a reference such as "each portion that receives light".

[0052] In some examples, each partially reflective element includes a light-transmitting element (i.e., a light-transmitting element) coated with a partially reflective coating. A light-transmitting element is any material through which light can travel, for example, through which more than 80% or 90% of light incident on it is transmitted (rather than absorbed or reflected). Suitable examples of light-transmitting elements can be made of materials such as glass, polycarbonate, and / or resins (e.g., PMMA). The partially reflective coating is any coating that partially reflects light, such as a thin coating of aluminum or silver, although other embodiments are contemplated, such as any material with a high refractive index (n>1.5 or n>1.7).

[0053] As another example, a partially reflective coating may include a dichroic coating and / or a stack of one or more films or plates. An example of a dichroic coating is a multilayer stack of thin materials with different refractive indices (similar to a distributed Bragg reflector). The stacked reflectivity varies depending on the wavelength (and the angle of incidence).

[0054] A stack of one or more films or plates can be configured such that (cumulative) Fresnel reflections leaving the stack interface cause incident light to be partially reflected and partially transmitted.

[0055] In other examples, the partially reflective element includes a perforated reflective element. A suitable example of a perforated reflective element is a perforated metal reflector, although other examples will be apparent to those skilled in the art. In some embodiments, each partially reflective element includes a light-transmitting element coated with a pattern of partially reflective or fully reflective patches. In these embodiments, light incident on the partially reflective element is spatially separated.

[0056] Preferably, each LED element in the array of LED elements includes a light-emitting diode, an LED, and a lens configured to guide the light emitted by the light-emitting diode.

[0057] In some examples, the optical elements also include a carrier configured to couple each partial reflective element to an array of LED elements.

[0058] These and other aspects of the invention will become apparent from the embodiments described below. Attached Figure Description

[0059] To better understand the invention and to more clearly illustrate how to implement it, reference will now be made to the accompanying drawings by way of example only, in which:

[0060] Figure 1 An LED element used in an embodiment of the present invention is shown;

[0061] Figure 2 This is a side view showing the components of an LED illuminator according to an embodiment;

[0062] Figure 3 This is a side view showing the components of an LED illuminator according to another embodiment;

[0063] Figure 4 This is a side view showing the components of an LED illuminator according to yet another embodiment; and

[0064] Figures 5 to 10 A top view is shown of different configurations of LED luminaires according to various embodiments. Detailed Implementation

[0065] The invention will be described with reference to the accompanying drawings.

[0066] It should be understood that the detailed descriptions and specific examples, while indicating exemplary embodiments of the apparatuses, systems, and methods, are intended for illustrative purposes only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatuses, systems, and methods of this disclosure will become better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that the drawings are merely schematic and not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to indicate the same or similar parts.

[0067] This invention provides an optical element for an LED illuminator, comprising an LED array of LED elements. The optical element includes one or more partially reflective or partially transmissive elements having a light-incident surface positioned perpendicular to a plane of the LED array. The partially transmissive element reflects light received by the partially transmissive element using at least the light-incident surface. In this way, the partially reflective element creates a virtual source or virtual LED element by reflecting a portion of the light emitted by the LED elements, while allowing the original or "real" LED element to remain visible through the partially transmissive light. The partially reflective element is positioned such that the virtual LED element is located between adjacent LED elements from which the partially reflective element receives light directly.

[0068] While the embodiments are found to have specific uses in industrial lighting applications such as street lighting or factory lighting, they can be used in any lighting fixture that includes an LED array of LED elements.

[0069] Throughout this disclosure, under the assumption that absorption or scattering is negligible, it is assumed that any light that is not reflected is transmitted through the partially reflective element. Therefore, any reference to a% of light in this disclosure may refer to a% of non-absorbed and / or non-scattered light.

[0070] Figure 1 An LED element 100 for use in an embodiment of the present invention is shown. The LED element 100 includes a light-emitting diode (LED) 110 and a lens 120 for shaping the light emitted by the LED 110. The LED element 100 is located in a plane 190, which may be the plane containing all the elements of a larger LED array. The lens 120 may be replaced by any other suitable beam-shaping optics. Figure 1 This is a cross-sectional view of LED component 100.

[0071] The lens 120 of the LED element 100 is configured such that the shape / pattern 150 of the light emitted by the LED 110 has mirror symmetry with respect to a plane 195 perpendicular to the plane 190 in which the LED element is located. The LED element shown has a single mirror 195.

[0072] exist Figure 1 In the diagram, an exemplary shape or pattern 150 of light is schematically shown in a manner similar to a conventional C-plane, and is intended to improve contextual understanding. The edges of the shown shape represent the light intensity relative to the direction of light from LED 110, where an increasing distance from LED 110 represents an increase in light intensity radiated in that direction.

[0073] Those skilled in the art will understand that the shape / pattern 150 of light can be different for different cross sections of the LED element (e.g., asymmetrical in other planes).

[0074] The LED element shown can be used for a specific purpose, such as in street lighting. For example, a long, narrow lighting pattern on a road can be created by positioning two intensity peaks 151, 152 of the light emitted from the LED element to fall in two directions along the road (away from the LED element 100). To form the intensity peaks, the lens bulges, as shown, such that the two peaks imply a lens with two convex sides. This helps to provide effective and uniform illumination along the road.

[0075] LED element 100 is merely one example of a suitable LED element applicable to embodiments of the present invention. Other LED elements may be associated with more than one mirror plane and / or not associated with any mirror plane (i.e., without mirror symmetry).

[0076] Preferably, the LED elements used in this disclosure have a limited number of mirrors to provide efficient LED elements with a suitable beam distribution for specific use case scenarios, such as road / street lighting. Such LED elements are particularly advantageous when adopted or used in the LED luminaires described herein.

[0077] Those skilled in the art will understand that LED element 100 is merely one example of a suitable LED element, and other embodiments (or examples) for LED elements will be readily apparent to those skilled in the art.

[0078] Figure 2 An LED illuminator 200 according to an embodiment of the present invention is shown. The LED illuminator 200 includes an LED array 210 formed of a plurality of LED elements 215, 216 and an optical element 220. The optical element 220 is formed of one or more partially reflective elements 250, 251, 260, each partially reflective element 250, 251, 260 being positioned to receive light directly from the LED elements 215, 216.

[0079] The LED array 210 can be mounted on a printed circuit board (PCB) 295, a substrate, or any other suitable carrier. The PCB can be formed from any suitable material, such as paper, fiberglass (cloth), aluminum, resin, etc. The substrate can include any suitable material, such as silicon, SiO2, Al2O3, TiO2, etc.

[0080] Optical element 220 may also include carrier 229, for example formed of one or more carrier elements, configured to couple each partial reflective element to the array of LED elements, for example via a printed circuit board 295 (or other carrier mechanism, if present). The carrier may include, for example, silicon, steel, aluminum, or any other suitable mounting mechanism. The carrier may be omitted, in which case the partial reflective elements are mounted directly on the PCB or other carrier mechanism.

[0081] The LED array is located within a first plane 290, such that each LED element 215, 216 of the LED array is located within the first plane 290. Each LED element may be labeled as a “real light source” or a “real LED element.” The first plane 290 may, for example, be parallel to the plane of a printed circuit board 295 (or other suitable carrier). For the purposes of the following description, the first plane defines a horizontal plane of the LED array (e.g., a horizontal distance is a distance along an axis parallel to the first plane).

[0082] Each of the partially reflective elements 250, 251, and 260 includes a light incident surface 255 onto which light 280 emitted by LED elements 215 and 216 is incident. The light incident surfaces 255 are arranged perpendicular to the first plane 290. Preferably, the light incident surfaces are flat and / or smooth to reduce scattering effects. A flat surface may be a surface with an offset angle of less than 5 degrees (preferably less than 1 degree). A smooth surface may be a surface with a root mean square (RMS) roughness height of no more than 150 nm (preferably less than 80 nm, more preferably less than 50 nm).

[0083] At least one partial reflective element 250, 251 is positioned between two adjacent LED elements and is arranged to directly receive light from the (single) LED element (i.e., light that does not pass through or otherwise interact with the other partial reflective element). A partial reflective element positioned in this manner may be designated as a central partial reflective element or a non-edge partial reflective element.

[0084] The light incident surface 255 can be the outermost layer of a partially reflective element, or it can be an inner layer (e.g., if the light incident surface is coated beforehand with a protective (preferably transparent) medium). As will be explained later, a light incident surface is a surface or interface that interacts with light to at least partially reflect it.

[0085] Each partial reflective element 250, 251, 260 is configured to reflect a first portion 281 of light 280 incident on the partial reflective element and transmit a second portion 282 of light incident on the partial reflective element. The partial reflective elements 250, 251 use a light-incident surface 255 (and optionally, one or more other interfaces) to reflect light, such that the first portion 281 of the reflected light includes at least some of the light reflected using at least the light-incident surface. In other words, the light-incident surface 255 facilitates reflection performed by the partial reflective elements.

[0086] By partially reflecting the received light, the first portion 281 appears to originate from the virtual sources 218, 219 (or “virtual LED elements”) located on the side of the LED elements, thereby increasing the apparent density of LED elements in the LED array.

[0087] Therefore, the light incident surface 255 is defined as a surface for reflecting light by the partial reflective elements 250, 251, 260, and can facilitate full or partial reflection performed by the partial reflective elements 250, 251.

[0088] By using light incident surfaces to make the light emitted from individual LED elements appear to originate from the same virtual source 218, 219 (e.g.) rather than from different virtual sources, the apparent density of the LED array is made more uniform. This configuration also reduces the likelihood that light will be reflected back to the LED elements (instead of being output by the LED illuminator 200).

[0089] Some reflective elements can be configured such that the reflection of all directly received light appears to originate from the same virtual source. This can be achieved by arranging all interfaces (which contribute to light reflection) parallel to each other and perpendicular to the first plane 290.

[0090] In some examples, the intensity distribution of the LED element has mirror symmetry with respect to one or more planes (mirror planes), which are typically perpendicular to the plane containing the LED element (or LED array). Figure 1 An example of such an LED element with single-plane mirror symmetry is shown, in which each partial reflective element can be positioned parallel to the mirror surface.

[0091] Preferably, the light intensity distribution emitted by each LED element is the same.

[0092] In some embodiments, the intensity distribution of the LED element has mirror symmetry with respect to a finite number of planes (mirrors), such that the finite number of planes is, for example, one plane (e.g., ...). Figure 1 (As shown), 2 or 4 planes. In such an embodiment, preferably, each partial reflective element is positioned parallel to the mirror surface. Of course, it is conceivable that the intensity distribution of the LED element has perfect rotational symmetry, i.e., an infinite number of mirrors.

[0093] Preferably, the partial reflective elements 250, 251 are configured such that the transmission and / or reflection of light incident on them (e.g., on the light incident surface) are specular or near-specular. This helps to ensure that the overall (angular) light distribution remains effectively constant throughout the LED illuminator.

[0094] In other words, the introduction of a (small) diffuse component of the light reflected or transmitted by one or more partially reflective elements can smooth the light distribution from the LED illuminator, eliminating the need for a separate light diffuser. In particular, it is preferable that the dominant direction of the specularly reflected or transmitted light is maintained, i.e., so-called forward scattering. The deviation from the specular direction can be made as described by a Gaussian distribution with a standard deviation of 0.5–5 degrees (to achieve a "small" diffuse component).

[0095] The light incident surface of each partial reflective element can be positioned parallel or perpendicular to an imaginary line passing through two adjacent LED elements (this can vary for different partial reflective elements).

[0096] Each central partial reflective element 250, 251 can be positioned such that a virtual source of light 218 (or “virtual LED element”) reflected by the partial reflective element is positioned between two adjacent LED elements (including LED elements from which the partial reflective element receives light directly).

[0097] Specifically, the virtual LED element can be positioned between 0.2 and 0.6 times the distance from the LED element 215 from which the partial reflective element 250 directly receives light, since the adjacent LED elements 216 are far apart.

[0098] For example, when the adjacent LED element 216 is far away from the LED element, the virtual LED element 218 can be positioned at approximately half (±5% or ±1%) of the distance from the central portion reflective element 250 from which the LED element 215 directly receives light, or at an odd integer multiple of that distance, because the adjacent LED element 216 is far away from the LED element.

[0099] As shown in the figure, this can be achieved by positioning each central part reflective element such that the horizontal position of each central part reflective element intersects with an imaginary line passing through the first LED element 215 (i.e., the LED element from which the central part reflective element directly receives light) and the second LED element 216 (adjacent LED elements) at an intersecting position, wherein the distance d2 between the intersecting position and the first LED element 215 is between 0.1 and 0.4 times the distance d1 between the first LED element 215 and the second LED element 216.

[0100] In other words, the distance d2 between each central part reflective element and its directly receiving LED element is between 0.1 and 0.4 times the distance d1 between each central part reflective element and its directly receiving LED element and its adjacent LED element.

[0101] Preferably, the distance between each central reflective element and its directly receiving LED element is between 0.2 and 0.3 times the distance between the directly receiving LED element and its adjacent LED element, and more preferably between 0.23 and 0.27 times that distance. This makes the virtual LED elements appear more concentrated between two LED elements, thereby increasing the apparent positional uniformity / effective positional uniformity of the real and virtual LED elements in the entire LED array.

[0102] When the LED elements of an LED array are positioned with a regular pitch, the central reflective element can be positioned between 0.1 and 0.4 times the pitch of the LED element. Preferably, the central reflective element is positioned between 0.2 and 0.3 times the pitch of the LED element.

[0103] As previously described, for distinction, the previously described partial reflective element (located between two adjacent LED elements) can be designated as a "central partial reflective element". Optical element 220 may also include one or more "side partial reflective elements" 260, each similar to the previously described (central) partial reflective element 250, but not positioned between two adjacent LED elements. Instead, the side partial reflective elements 260 are positioned at the side edges of the LED array. Other elements of the side partial reflective elements 260 may be implemented as with the previously described partial reflective elements.

[0104] Specifically, the side-reflective element may be located on an imaginary line intersecting the LED element (from which the side-reflective element directly receives light) and the adjacent LED element, but not between the LED element (from which the side-reflective element directly receives light) and the adjacent LED element.

[0105] The effect of the side-mounted reflective elements is to provide virtual LED elements 219 outside the boundaries of the LED array 210. This increases the apparent size of the LED array and thereby increases the average brightness across the entire LED illuminator, thus improving viewer comfort by reducing glare.

[0106] The horizontal distance d2 between the side reflective element 260 and the LED element 215 (at the edge of the LED array) can be between 0.2 and 0.6 times the distance between the side reflective element 260 and the LED element 215 that directly receives light from it and its adjacent LED element 216.

[0107] In some embodiments, each partial reflective element 250, 251, 260 is one of two partial reflective elements 250, 251, 260 that form a group of two partial reflective elements.

[0108] The two partial reflective elements of this group are positioned parallel to each other and are positioned such that the light reflected by the first partial reflective element 250 is a mirror image of the light reflected by the second partial reflective element 251.

[0109] This is achieved in the illustrated embodiment by positioning a first partial reflective element 250 on a first side of a first LED element 215 and positioning a second partial reflective element 251 on a second side of a second LED element 216, wherein the first and second partial reflective elements are parallel to each other and the distribution of light output from the first and second LED elements is substantially the same (within reasonable manufacturing tolerances).

[0110] The distance between the first part of the reflective element 215 and the first LED element is the same as the distance between the second part of the reflective element and the second LED element 216.

[0111] In a particular example, each of the partial reflective elements 250, 260 in a set of partial reflective elements is positioned on either side of the same LED element 215. However, this is not required.

[0112] As described above, it will be clear that the light 280 (emitted from LED element 215) incident on the (central or side) reflective elements 250, 251, 260 can conceptually be divided into reflected light 281 and transmitted light 282, and the light incident surface 255 perpendicular to the first plane 290 contributes to at least some of the reflection process. In other words, the light incident surface is used to perform at least some of the reflection.

[0113] The light-incident surface thus acts as an interface for reflecting some of the light incident upon it. Partial reflective elements may use one or more interfaces (e.g., transition regions between different materials or substances, such as glass-air interfaces or air-metal interfaces) to perform reflection.

[0114] The incident light can be divided in the following ways: by chromaticity (e.g., different wavelengths of light are reflected or transmitted); by intensity (e.g., a certain amount of light of each wavelength is reflected or transmitted); and / or by space (e.g., some reflective elements in certain areas transmit light, while other areas reflect light).

[0115] Of course, these divisions can be combined, for example, based on both intensity and wavelength, such that a certain percentage of a first group of wavelengths is transmitted (while the remainder of that group is reflected), and a different percentage of a second group of wavelengths is transmitted (while the remainder of that group is reflected). Other suitable combinations will be apparent to those skilled in the art.

[0116] In one embodiment, the partial reflective element includes a perforated reflective element, i.e., a reflective element comprising one or more perforations or holes. The surface of the perforated reflective element can serve as a light-incident surface. Suitable examples of reflective elements may include metallic reflectors. Light reaching the hole is transmitted through the partial reflective element, and light incident on other portions of the perforated reflective element (i.e., the light-incident surface) is reflected. In this way, light incident on the partial reflective element is partially transmitted (through the perforation) and partially reflected (from other portions of the perforated reflective element). Therefore, light incident on the partial reflective element is spatially divided into transmitted light and reflected light.

[0117] A perforated reflective element is an example of a partially reflective element that uses only one interface to perform reflection, although both sides of a perforated reflective element can be reflective (for light received from either side).

[0118] In another embodiment, the partially reflective element includes a transmissive (e.g., transparent) element having a partially reflective coating that forms the entire side of the partially reflective element (e.g., the side on which light is incident). In this embodiment, the partially reflective coating acts as a light-incident surface. The transmissive element provides support for the partially reflective coating. Light incident on the partially reflective coating is partially reflected and partially transmitted.

[0119] To prevent light transmitted by a partially reflective element from being reflected as it leaves the element, a partially reflective coating can be formed only on a single side of the transmission element, such as the side closest to the LED element or the "light-entry surface" (e.g., light-incident surface 255). Alternatively, the partially reflective element can be positioned on the light-exit surface of the transmission element such that light passes through the transmission element before being partially reflected. Providing a partially reflective coating on a single side of the transmission element increases the uniformity of light intensity output by each dummy LED element on the LED array.

[0120] In one sub-implementation, the partially reflective coating is configured to divide only the light incident upon it according to intensity (e.g., transmitting a certain amount of all the light incident upon it and reflecting a certain amount of all the light incident upon it). This can be achieved using a thin coating of a metallic reflector (such as aluminum or silver), but other methods will be apparent to those skilled in the art. As another example, a stack of thin films / plates can be used such that the total Fresnel reflection at the stack interface reaches a certain amount. As yet another example, a single coating (such as SNO2, Sb2O5, ZrO2, TiO2, CeO2, ZrO2, or a polycarbonate coating) of a material with a high refractive index (e.g., n>1.5, n>1.65, n>1.7, or n>1.9) can be used.

[0121] In another sub-implementation, the partially reflective coating is configured to segment incident light according to chromaticity, for example using a dichroic coating (such as a multilayer stack of thin materials with different refractive indices, similar to a Bragg reflector). Thus, a certain percentage of light of the first set of wavelengths incident upon it can be transmitted, while a certain percentage of light of the second set of wavelengths can be reflected. It is known that the angle of incident light can affect the wavelengths of the transmitted / reflected light, but will not significantly change the total ratio of transmitted / reflected light (assuming the incident light is white).

[0122] If some of the transmission elements are positioned parallel to the mirror and each ray has its own unique corresponding mirror reflection ray, then the spectrum of the LED illuminator will be the same as the spectrum of an illuminator element without that optical element.

[0123] In other embodiments, the partial reflective element omits the transmissive element, for example, such that the partial reflective coating is provided as a separate partial reflective element. This is possible when the partial reflective coating itself will be self-supporting, for example if the partial reflective element comprises a stack of thin films / plates, etc.

[0124] In a simple example, a partial reflective element includes a plate of a transmissive element because light incident on such a plate will cause Fresnel reflection, typically between 8-20% (depending on the angle of incidence / material). One or more surfaces of the plate of the transmissive element can act as light incident surfaces.

[0125] The partial reflective element can be configured to reflect 25% to 75% of the received light, for example, 40%-60% of the received light, 45%-55% of the received light, or 48%-52% of the received light. In a particular example, the partial reflective element can be configured to reflect about 50% (±1% or ±0.5%) of the received light.

[0126] Partial transmission elements can be configured to transmit 25%-75% of the received light, for example, 40%-60%, 45%-55%, or 48%-52%. In specific instances, partial transmission elements can be configured to transmit approximately 50% (±1% or ±0.5%) of the received light.

[0127] In a more preferred embodiment, a portion of the transmission element may be configured to transmit at least 45% of the received light and reflect at least 45% of the received light, for example, to transmit at least 48% of the received light and reflect at least 48% of the received light, or to transmit at least 49% of the received light and reflect at least 49% of the received light.

[0128] A more uniform distribution between transmitted and reflected light (e.g., tending towards 50-50) leads to a balance in the apparent brightness of the real and virtual light sources, thereby further reducing glare without the need to provide additional “real” LED elements.

[0129] Therefore, preferably, the amount of light transmitted by each partial reflective element and the amount of light reflected by each partial reflective element are substantially the same (e.g., ±10%, more preferably ±5% or even more preferably ±1%).

[0130] for Figure 2 In the illustrated embodiment, the height of each (center or side) portion of the reflective element 250, 251 is preferably not less than 2 mm, for example not less than 4 mm. In such an example, the height is preferably not greater than 10 mm, for example, the height can be between 2 mm and 10 mm, and / or between 4 mm and 10 mm.

[0131] Preferably, the height of the partial reflective element should be as large as possible (while, for example, if it has a protective element, the partial reflective element is still assembled within the entire housing of the illuminator).

[0132] The height of each partial reflective element 250, 251 can be, for example, not less than 10% of the distance between two adjacent LED elements, for example, not less than 50% of the distance between two adjacent LED elements. The greater the height of the partial reflective element, the greater the reduction of glare by increasing the uniformity of brightness distribution on the LED illuminator.

[0133] exist Figure 2 In the diagram, partial reflective elements 250, 251, and 260 are shown positioned at the same distance from the LED element from which they directly receive light. In other words, the distance between the first partial reflective element 250 and the first LED element 215 (from which the first partial reflective element 250 directly receives light) is shown to be substantially the same as the distance between the second partial reflective element 251 and the second LED element 216 (from which the second partial reflective element 251 directly receives light).

[0134] However, in some embodiments, at least two (e.g., each) partial reflective elements are positioned at different distances (e.g., pseudo-random distances) from their corresponding LED elements. This slight randomization or variation in the relative positions of the partial reflective elements (relative to the LED elements) increases the uniformity of the brightness distribution provided by the LED illuminator, achieved by reducing the impact of the partial reflective elements (e.g., reducing the appearance of dark lines that might be produced by the partial reflective elements along their length).

[0135] Preferably, the distance is no greater than ±10% of the difference between them.

[0136] Another characteristic that can affect the effectiveness of an LED illuminator is the shape of the partial reflective elements (e.g., thickness or rounded corners). Preferably, as shown, each partial reflective element has a generally cubic shape with one or more interfaces (e.g., light incident surface 255) that partially reflect and partially transmit light incident thereon.

[0137] The thickness of each partial reflective element is preferably no greater than 1 mm, for example, no greater than 0.8 mm, for example, no greater than 0.5 mm. The thickness of the partial reflective element can be defined as the maximum dimension along the direction in which the partial reflective element is disposed between two LED elements. The lower the thickness, the fewer artifacts (generated by interaction with the two sides of the partial reflective element) in the luminous intensity of the LED element, and the higher the relative luminous intensity of the entire illuminator (due to reduced absorption).

[0138] Preferably, the top edge of each partial reflective element (i.e., the edge furthest from the first plane) has a rounded corner of not less than 0.2 mm (radius), and preferably not less than 0.1 mm (radius). The lower the rounded corner radius, the better the luminous output of the illuminator (due to reduced scattering).

[0139] Figure 3 An LED illuminator 300 according to another embodiment of the present invention is shown.

[0140] Figure 3 LED lighting 300 and Figure 2 The difference in the LED illuminator 200 is that the partial reflective elements 350, 351 of the optical array 320 are configured to further receive: a first portion of light 394 reflected by at least one other partial reflective element; and / or a second portion of light 395 transmitted by the at least one other partial reflective element, and are also configured to partially reflect and partially transmit the received first portion of light and / or the second portion of light.

[0141] In other words, light transmitted by one partially reflective element 350 is redirected to a partially transmitted, partially reflected state, manipulated by another partially reflective element 351. This creates multiple virtual sources at a considerable distance from the original source. Furthermore, these virtual sources can be located outside the area of ​​the real light source.

[0142] For the purpose of understanding, Figure 3 The diagram illustrates some of the transmission and reflection experienced by light 390 emitted by LED elements 315 of LED array 310. It can be seen how a single ray interacting with multiple different partially reflective elements 350, 351 can result in the creation of multiple different virtual LED elements or light sources.

[0143] The LED illuminator 300 increases the effective size of the (light) source area, which further reduces glare throughout the LED illuminator.

[0144] Furthermore, using multiple partially reflective elements in this way to reflect / transmit light emitted by the LED elements allows for the use of partially reflective elements with reduced reflectivity, for example, by using cheaper, more abundant, or more economical / ecological materials. This is because using multiple partially reflective elements creates additional virtual elements (e.g., beyond the physical boundaries of the LED array). In this way, the total amount of light output by the illuminator is maintained while further reducing glare.

[0145] In a specific example, the length or height of the partial reflective element (partially the length / height of the light incident surface of the partial reflective element) in the direction perpendicular to the first plane 290 may be no less than 0.4 times the distance between two adjacent LED elements of the LED array, preferably no less than 1 times that distance, and even more preferably no less than 2 times that distance. The longer / higher the partial reflective element, the greater the extension of the apparent size of the illuminator.

[0146] As an example only, when the distance between two adjacent LED elements in an LED array is approximately 25 mm, the length and height of each partial reflective element are preferably not less than 10 mm, for example, not less than 15 mm, for example, not less than 45 mm or 50 mm. Other suitable distances between two adjacent LED elements will be apparent to those skilled in the art, for example, between 3 mm and 50 mm, for example, between 3 mm and 10 mm (for indoor applications), or between 15 and 30 mm for outdoor lighting applications. It is conceivable, for example, that larger distances, such as between 10 cm and 30 cm, are feasible for large-area lighting fixtures covering ceilings.

[0147] Compared to partially reflective elements in the center of an LED array, partially reflective elements closer to the edges of the LED array will have less interaction with light. Therefore, partially reflective illuminators with higher reflectivity towards the sides of the LED array compared to those towards the center / middle may be advantageous. This will result in improved uniformity of the apparent brightness of the light output from the virtual source on the illuminator.

[0148] Similarly, light emitted at a larger angle relative to the first plane interacts less with the partially reflective elements compared to light emitted closer to the first plane (at a lower angle). Therefore, it is advantageous that at least one partially reflective element has greater reflectivity at a location further away from the first plane compared to a location closer to it. As an example, the partially reflective element can have a gradient of reflectivity relative to its distance from the first plane or the LED array, resulting in higher reflectivity at the far end of the board and lower reflectivity closer to the PCB. This gradient can be a gradual gradient or a stepped gradient. Such an embodiment will result in improved brightness uniformity of the light emitted by the LED illuminator, achieved by increasing the brightness uniformity of the dummy LED elements on the LED array.

[0149] Figure 4 An LED illuminator 400 according to another embodiment of the present invention is shown. Figure 4 LED lighting 400 and Figure 2 The difference in the LED illuminator 200 is that the optical element 420 includes one or more additional partial reflective elements 461, 462. For clarity, only a portion of the optical element associated with a single LED element is shown.

[0150] Specifically, the optical element 420 includes a partially reflective element 450 positioned to directly receive light emitted by the LED elements 415 of the array 410 of LED elements. This partially reflective element is configured similarly to the partially reflective elements previously described.

[0151] Optical element 420 also includes additional partial reflective elements 461, 462, each of which differs from partial reflective element 450 in that it does not directly receive light emitted from the LED element. Instead, the additional partial reflective elements 461, 462 only receive light transmitted and / or reflected from partial reflective element 450 and / or another additional partial reflective element 461.

[0152] As shown in the figure, this creates additional virtual sources dispersed between two adjacent LED elements, thereby increasing the brightness uniformity of the light emitted by the illuminator. In particular, each additional partially reflective element can create a virtual source or virtual LED element located between the LED element from which each additional partially reflective element receives non-reflected light (e.g., only transmitted light) and the adjacent LED element.

[0153] Other features of the additional partial reflective elements 461, 462 can be implemented as with the previously described partial reflective elements. For example, each partial reflective element is adapted to partially reflect and partially transmit light incident thereon. Similarly, each additional partial reflective element includes a light incident surface perpendicular to the plane of the LED array, which facilitates the reflection of light by the additional partial reflective elements.

[0154] The (horizontal) distance between each additional partially reflective element and its LED element that receives non-reflective light (e.g., only transmitted light) is preferably between 0.1 and 0.4 times the distance between the LED element 415 and the adjacent LED element 416, and more preferably between 0.2 and 0.4 times the distance between the LED element and the adjacent LED element.

[0155] The precise distance will depend on the position of the partial reflective element 450, which transmits light incident on the additional partial reflective element.

[0156] Preferably, the distance between each additional partial reflective element and its LED element that receives non-reflective light (e.g., only transmitted light) is a multiple of the distance between the partial reflective element that transmits non-reflective light (incident on the additional partial reflective element) and the LED element.

[0157] Figures 5 to 10 Some top views are shown of suitable configurations or arrangements of partial reflective elements relative to an LED array. Exemplary or potential locations of virtual sources for partial reflective elements in different positions / arrangements are shown in dashed outlines.

[0158] Figure 5 An LED illuminator 500 is shown, comprising a 2D rectangular LED array of LED elements 515, 516, wherein a lens provides an intensity distribution with mirror symmetry relative to a (single) plane. Each partial reflective element 550 is arranged perpendicular to the plane of the LED array and is positioned at one-quarter of the distance between the first LED element 515 and the second LED element 516 of the array of LED elements.

[0159] In a specific example, and as shown in the figure, the intensity distribution of the LED elements has mirror symmetry with respect to a (single) plane, and each partial reflective element is positioned parallel to the mirror surface of at least one LED element, resulting in the reflection and transmission portions of the beam still accumulating into the original beam distribution.

[0160] Figure 6Another LED illuminator 600 is shown, comprising a 2D rectangular LED array of LED elements 615 and 616, wherein the lens provides a light intensity distribution with quadratic symmetry (i.e., such that the intensity distribution is mirror-symmetric with respect to two orthogonal planes). Each partial reflective element 650 is again positioned perpendicular to the plane of the LED array and is positioned at one-quarter of the distance between the first LED element 615 and the second LED element 616 of the LED element array.

[0161] In a specific example, and as shown in the figure, in order to maintain the original beam distribution, each partial reflective element is repositioned as a mirror parallel to at least one LED element. Because the light intensity distribution of the LED elements has a quadratic symmetry, the different partial reflective elements can be perpendicular to each other.

[0162] Figure 6 The configuration shown may also include one or more diagonally positioned partially reflective elements (e.g., parallel to the diagonals of each LED element). This is particularly advantageous if the intensity distribution of each LED element has mirror symmetry (e.g., perfect rotational symmetry) along the diagonals of the LED element.

[0163] Figure 7 Another LED illuminator 700 is shown, comprising a 2D rectangular LED array of LED elements 715, 716, wherein the lens provides an intensity distribution with perfect rotational symmetry (e.g., effective even in all directions, such that it is mirror-symmetric in all planes perpendicular to the LED array). The LED elements are staggered.

[0164] Each reflective element 750 of the LED illuminator 700 is again arranged perpendicular to the plane of the LED array and thus parallel to the mirror surface of each LED element, but positioned at one-eighth of the distance between the first LED element 715 and the second LED element 716.

[0165] In the example shown, the height of each partial reflective element 750 is high enough that the light emitted by the LED element can interact with multiple (e.g., at least two) partial reflective elements. It should be noted that only a virtual source corresponding to the illustrated LED element is shown.

[0166] Figure 8 Another LED illuminator 800 is shown, comprising a 2D rectangular LED array of LED elements 815, 816, wherein the lens provides an intensity distribution with rotational symmetry (e.g., effective even in all directions, such that it is mirror-symmetric in all planes perpendicular to the LED array). The LED elements are again staggered.

[0167] Each reflective element 850 of the LED illuminator 800 is again arranged perpendicular to the plane of the LED array, but positioned at a distance one-quarter of the distance between the first LED element 815 and the second LED element 816. This results in the LED illuminator having effective LED elements (i.e., a combination of real and virtual LED elements) that are uniformly spaced apart from each other, thus achieving improved brightness uniformity.

[0168] Figure 9 Another LED illuminator 900 is shown, comprising a 2D rectangular LED array of LED elements 915 and 916, wherein the lens provides an intensity distribution with rotational symmetry (e.g., effective even in all directions, such that it is mirror-symmetric in all planes perpendicular to the LED array). The LED elements are again staggered.

[0169] Each of the partial reflective elements 950A, 950B of the LED illuminator 900 is again arranged perpendicular to the plane of the LED array (and here therefore parallel to the mirror surface of the output light intensity). Each partial reflective element is again positioned at one-quarter of the distance between the first LED element 915 and the second LED element 916.

[0170] Compared to the previous example, each partial reflective element is positioned diagonally here. In particular, the first set of partial reflective elements is configured to be offset or tilted by 60° relative to the second set of partial reflective elements.

[0171] Figure 10 Another LED illuminator 1000 is shown, comprising a 2D rectangular LED array of LED elements 1015, wherein the lens provides an intensity distribution with rotational symmetry (e.g., effective even in all directions, such that it is mirror-symmetric in all planes perpendicular to the LED array). The LED elements are again staggered.

[0172] Each part of the LED illuminator 1000, the reflective elements 1050A, 1050B, 1050C, is again arranged in a plane perpendicular to the LED array (and therefore parallel to the mirror surface of the output light intensity).

[0173] The partial reflective elements are positioned diagonally (i.e., diagonally placed partial reflective elements 1050A and 1050B) and horizontally (i.e., horizontally placed partial reflective elements 1050C).

[0174] Multiple dummy sources 1031, 1032 associated with a single LED element are shown with dashed / dotted lines. The first set of dummy sources 1031 is shown with dashed lines and represents a dummy source generated by interacting with or encountering only a single partial reflective element. The second set of dummy sources 1032 is shown with dotted lines and represents a dummy source generated by interacting with or encountering two reflective elements (and therefore, this second set of dummy sources does not exist if the partial reflective elements are not high enough).

[0175] Compared to other examples, Figure 10 The configuration provides 1000 LED illuminators with an increased number of virtual sources, thereby further reducing perceived glare.

[0176] Figure 10 The configuration may include additional reflective elements positioned vertically relative to the 2D rectangular LED array, for example, using... Figure 6 The method shown exists, which will further increase the number of virtual sources.

[0177] certainly, Figure 9 and Figure 10 The LED illuminator shown can be configured as a non-staggered array of LED elements (e.g., LED elements that are equally distributed in the vertical and horizontal directions).

[0178] exist Figures 5 to 10 In all the embodiments shown, some reflective elements are positioned parallel to the rows of LED elements. Although this feature is not essential, it does form a preferred aspect of the invention to ensure that the virtual source is positioned between the actual LED elements, thereby increasing the uniformity of the light output from the LED illuminator.

[0179] exist Figures 5 to 10 In all the embodiments shown, each partial reflective element is positioned as a mirror parallel to the LED element. Although this feature is not essential, it does form a preferred aspect of the invention to ensure that the (angular) light distribution of the entire LED illuminator remains effectively constant.

[0180] exist Figures 5 to 10 In the illustrated embodiment, the distance between the partially reflective element and the LED element that directly receives light is one-eighth or one-quarter of the distance between the LED element and adjacent LED elements. However, other distances are conceivable, for example, between 0.1 and 0.4 times the distance between the LED element and adjacent LED elements.

[0181] In the context of this disclosure, a “transmitting element” is any material (e.g., glass) that transmits most of the light incident thereon, such as at least 80% of the non-absorbed light incident thereon, and preferably at least 90% of the non-absorbed light incident thereon.

[0182] In the context of this disclosure, adjacent LED elements are the closest LED elements located in a specific / predetermined direction along the first plane (i.e., the plane of the LED array). In the context of this disclosure, distance generally refers to horizontal distance, i.e., distance along the first plane.

[0183] Preferably, the partial reflective element has a very low absorptivity, for example, <20% of the incident light is absorbed, more preferably, <10% of the incident light is absorbed.

[0184] Those skilled in the art will understand that the virtual sources shown may not always be visible to a viewer of the LED illuminator viewed from a single direction, but are intended to represent the typical location of virtual sources across the entire LED illuminator. It should also be noted that only a few possible virtual sources may be shown (as the number of virtual sources can depend at least on the height of some reflective elements) and is provided purely for the purpose of improving understanding.

[0185] By studying the accompanying drawings, this disclosure, and the appended claims, those skilled in the art can understand and implement various variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to obtain benefit. If the term "suitable" is used in the claims or description, it should be noted that the term "suitable" is intended to be equivalent to the term "configured as."

[0186] Any reference numerals in the claims should not be construed as limiting the scope.

Claims

1. An LED lighting device (200, 300, 400, 500, 600, 700, 800, 900, 1000), comprising: An array (210, 310, 410) of LED elements (215, 216, 315, 415, 515, 516, 615, 616, 715, 716, 815, 816, 915, 916, 1015, 1016), each LED element configured to emit light, is disposed in a first plane (290); as well as Optical elements (220, 320, 420) comprising one or more partially reflective elements (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C), each partially reflective element being positioned to directly receive light emitted by the LED elements (215, 315, 415) of the array of LED elements and comprising a light incident surface (255) positioned perpendicular to the first plane. Each of the partial reflective elements is configured to reflect a first portion (281, 394) of the received light using at least the light incident surface and transmit a second, different portion (282, 395) of the received light. At least one of the partial reflective elements (250, 251) is positioned such that a virtual source (218) of the first portion of the directly received light reflected by the light incident surface is located between the LED element from which the partial reflective element directly receives light and the adjacent LED element.

2. The LED lighting device (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to claim 1, wherein: Each LED element (215, 216, 315, 415, 515, 516, 615, 616, 715, 716, 815, 816, 915, 916, 1015, 1016) in the array of LED elements is configured to emit light with a luminous intensity distribution having at least one mirror-symmetric plane. The light incident surface of each partial reflective element (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C) is positioned as a mirror-symmetric plane parallel to one or more luminous intensity distributions of the LED element from which each partial reflective element directly receives light.

3. The LED lighting device (200, 300, 400, 500, 600) according to claim 2, wherein, The luminous intensity distribution of light emitted by each LED element (215, 216, 315, 415, 515, 615, 616) of the array of LED elements has a finite number of mirror-symmetric planes.

4. The LED illuminator (200, 300, 400, 500, 600, 800, 900, 1000) according to any one of claims 1 to 3, wherein the distance between each partially reflective element (250, 251, 260, 350, 351, 450, 550, 650, 850, 950A, 950B, 1050A, 1050B, 1050C) and the LED element (215, 216, 315, 415, 515, 516, 615, 616, 815, 816, 915, 916, 1015, 1016) from which each partially reflective element directly receives light is between 0.1 and 0.4 times the distance between the LED element from which the at least one partially reflective element directly receives light and the adjacent LED element.

5. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein the thickness of each partial reflective element (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C) is not greater than 1 mm.

6. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein at least one partially reflective element (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C) is configured to further receive a first portion of light reflected and / or a second portion of light transmitted directly received by at least one other partially reflective element, and is further configured to partially reflect and partially transmit the received first portion of light and / or the second portion of light.

7. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein at least one partially reflective element (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C) has a length in a direction perpendicular to the first plane of not less than 0.4 times the distance between the at least one partially reflective element and the LED element to which it directly receives light, and the adjacent LED element.

8. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein, The first and / or second portions of the received light comprise not less than 25% and not more than 75% of the received light.

9. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to claim 8, wherein the first and / or second portions of the received light comprise not less than 45% and not more than 55% of the received light.

10. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein: The first portion of the received light comprises not less than 75% of the received light having wavelengths located within a first set of wavelengths; and the second portion of the received light comprises not less than 75% of the received light having wavelengths located within a second, different set of wavelengths.

11. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein at least one partially reflective element is configured such that, in the case that the received light comprises a plurality of light rays, each light ray is partially transmitted and partially reflected by the partially reflective element.

12. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein at least one partially reflective element comprises a light-transmitting element coated with a partially reflective coating.

13. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein at least one partially reflective element comprises a perforated reflective element and / or at least one partially reflective element comprising a light-transmitting element coated with a pattern of partially or fully reflective patches.

14. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein the array of LED elements comprises one or more rows of LED elements, wherein each partial reflective element is positioned parallel to the row of LED elements.

15. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to any one of claims 1 to 3, wherein each LED element comprises a light-emitting diode, i.e., an LED, and a beam-forming optical element configured to guide light emitted by the light-emitting diode.

16. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to claim 2, wherein the luminous intensity distribution of the light emitted by each LED element is the same.

17. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to claim 5, wherein the thickness of each partial reflective element (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C) is not greater than 0.8 mm.

18. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to claim 5, wherein the thickness of each partial reflective element (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C) is not greater than 0.5 mm.

19. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to claim 7, wherein the at least one partially reflective element (250, 251, 260, 350, 351, 450, 550, 650, 750, 850, 950A, 950B, 1050A, 1050B, 1050C) has a length in a direction perpendicular to the first plane that is not less than 1 times the distance between the at least one partially reflective element and the adjacent LED element from which it directly receives light.

20. The LED illuminator (200, 300, 400, 500, 600, 700, 800, 900, 1000) according to claim 12, wherein the light-transmitting element coated with a partially reflective coating comprises a dichroic coating and / or a stack of one or more films or plates.

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