Led array between flexible and rigid substrates

Abstract

A light source may include a transparent flexible substrate. A sparse array of light emitting diodes (LEDs) may be disposed on a transparent flexible substrate. The rigid substrate may be adhered to the transparent flexible substrate such that the sparse array of LEDs is located between the rigid substrate and the transparent flexible substrate. The rigid substrate may be adhered to the transparent flexible substrate with an adhesive layer. The sparse array of LEDs may be encapsulated in the adhesive of the adhesive layer. The refractive index of the adhesive may be between the refractive index of the transparent flexible substrate and the refractive index of the rigid substrate, including the refractive index of the transparent flexible substrate and the refractive index of the rigid substrate. The sparse array of LEDs may have a light emitting area that is less than or equal to a specified portion of the surface area of the sparse array, such as 5% or 1%.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 352,517, filed on June 15, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to sparse arrays of light emitting diodes (LEDs). Background Art

[0004] Efforts are currently underway to improve the technology using sparse arrays of LEDs, such as micro-LEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 A cross-sectional side view of an example of a light source is shown.

[0006] Figure 2 It shows that it can include Figure 1 A block diagram of an example of a light source visualization system.

[0007] Figure 3 and Figure 4 Shows Figure 1 Figures showing side views of a light source in various stages of assembly.

[0008] Figure 5 A flow chart showing an example of a method for manufacturing a light source.

[0009] Throughout the several views, corresponding reference numerals indicate corresponding parts. The elements in the drawings are not necessarily drawn to scale. The configurations shown in the drawings are merely examples and should not be construed as limiting in any way. DETAILED DESCRIPTION

[0010] For the purposes of this document, the term "micro-LED" is intended to be synonymous with an LED in a sparse array of LEDs. Efforts are currently underway to improve micro-LED display technology. For example, displays such as direct-view displays and projection displays can use micro-LEDs to improve efficiency and increase brightness.

[0011] In a direct-view micro-LED display, the LEDs may occupy a relatively small share of the display area. Because most of the display area is unaffected by the LEDs, the LEDs may not substantially change the optical properties of the surface on which they are assembled. For example, in the presence of LEDs mounted on a black surface, the black surface may remain black. Similarly, in the presence of LEDs mounted on a reflective surface, the reflective surface may remain reflective. Other examples and optical surface properties may also be used.

[0012] In some examples, micro-LEDs can be assembled onto a transparent flexible substrate. The transparent flexible substrate can then be laminated onto a substrate having desired optical properties, such as reflectivity, etc. Using a transparent flexible substrate in this manner can allow micro-LEDs to be applied to curved or irregularly shaped substrates, which may be incompatible with micro-LED assembly techniques using rigid flat substrates, such as wafers.

[0013] In some examples, the flexible substrate can be laminated to the substrate with the LED side facing down using a transparent adhesive having a thickness sufficient to encapsulate the micro-LEDs. For these and other examples, the transparent substrate and adhesive can also serve as a barrier that can protect the micro-LEDs from environmental influences. Because the transparent substrate can provide protection for the micro-LEDs, the transparent substrate can reduce or eliminate the need to use an additional transparent cover or protective layer to provide protection for the micro-LEDs.

[0014] Figure 1 A cross-sectional side view of an example of a light source 100 is shown. The light source 100 can include a sparse array of LEDs 102 (e.g., "micro-LEDs") disposed on a transparent flexible substrate 104 and a rigid substrate 106 adhered to the transparent flexible substrate 104 with an adhesive layer 108 such that the sparse array of LEDs 102 is located between the rigid substrate 106 and the transparent flexible substrate 104. The sparse array of LEDs 102 can be encapsulated in an adhesive 110 of the adhesive layer 108.

[0015] The transparent flexible substrate 104 may be a polymer sheet having a relatively high transmittance, or equivalently, a relatively low loss, due to absorption and scattering in the visible portion of the electromagnetic spectrum, such as between wavelengths of about 400 nm and about 700 nm. Suitable materials for the transparent flexible substrate 104 may include transparent polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), etc. The transparent flexible substrate 104 may have a thickness between about 20 μm and about 200 μm, although thicknesses outside this thickness range may also be used.

[0016] A sparse array of LEDs 102 may be disposed on a transparent flexible substrate 104. For purposes of this document, the term "sparse" is intended to mean that the light generating surface area of ​​the array is less than or significantly less than the total surface area of ​​the array. For example, the fill factor (e.g., the ratio of the light generating surface area to the total surface area) of the array may be less than or equal to a specified threshold, such as 10%, 5%, 4%, 3%, 2%, 1%, or another suitable threshold. As a specific example, the LEDs 102 may be arranged in a rectangular array, where the center-to-center spacing along one dimension is represented by the spacing x. Each LED 102 may have a light generating area sized along one dimension by a dimension s. The ratio of s divided by x may be less than or equal to 0.1. In the orthogonal dimension, a similar ratio applies, where the linear dimension of the light generating area is less than or equal to one-tenth of the linear center-to-center spacing of the LEDs 102. Combining the two linear dimensions, the surface area of ​​the light generating area of ​​the LEDs 102 is less than or equal to 1% of the surface area of ​​the array. In some examples, the light generating area of ​​each LED may be less than 200 μm on a side. In some examples, the light generating area of ​​each LED can be less than 50 μm on a side. Electrical traces can be deposited on the transparent flexible substrate 104 to power the LEDs 102 (e.g., deliver current to and from the LEDs 102). In some examples, the electrical traces can be metal traces that are narrow enough to be invisible under typical viewing conditions. In some examples, the electrical traces can be formed of one or more transparent conductive materials such as indium tin oxide (ITO).

[0017] In some examples, a sparse array of LEDs 102 may include two or more LEDs 102 that emit light at the same wavelength (or color). In some examples, a sparse array of LEDs 102 may include LEDs 102 that all emit light at the same wavelength. For example, a device such as a display may include a sparse array of LEDs 102 that all emit red light, a sparse array of LEDs 102 that all emit green light, and a sparse array of LEDs 102 that all emit blue light. In some examples, a sparse array of LEDs 102 may include two or more LEDs 102 that emit light at different wavelengths. For example, a device such as a display may include a sparse array of LEDs 102, some of which emit red light, some of which emit green light, and some of which may emit blue light. The red, green, and blue LEDs 102 may be arranged in repeating clusters, where each cluster forms a color pixel of the device. In some examples, the sparse array of LEDs 102 can include at least one LED that emits light at a visible wavelength (e.g., between about 400 nm and about 700 nm). In some examples, the sparse array of LEDs 102 can include at least one LED that emits light at an infrared wavelength (e.g., greater than about 700 nm). Such infrared wavelengths can be used for biometric sensing or other sensing techniques.

[0018] Because the sparse array of LEDs 102 (including the light emitting areas of the LEDs 102, corresponding electrical traces, and any corresponding circuitry) can have a relatively small fill factor, a majority of the surface area of ​​the sparse array of LEDs 102 can be transparent. For example, light incident on the sparse array of LEDs 102 (or incident from or on the transparent flexible substrate 104) mostly passes through the sparse array of LEDs 102, with only a relatively small portion being blocked by the light emitting areas and electrical traces of the sparse array of LEDs 102.

[0019] As a result, a sparse array of LEDs 102 can generate light on a surface and / or optical element (such as on a rigid substrate 106 described below) with additional functionality. For example, the surface and / or optical element can include a reflector with a specified reflectivity value. As another example, the surface and / or optical element can include a spectral filter with a specified reflectivity, transmittance, or absorptivity at one or more specified wavelengths. Other suitable functionality can also be used.

[0020] The rigid substrate 106 may be adhered to the transparent flexible substrate 104 .

[0021] In some examples, the rigid substrate 106 can be transparent. Suitable applications for the transparent rigid substrate 106 can include vehicle windshields, building windows, head-up displays, augmented reality headsets, etc. Suitable transparent materials for the transparent rigid substrate 106 can include glass, laminated glass, polycarbonate, or engineered plastics such as polymethyl methacrylate (PMMA).

[0022] In some examples, the rigid substrate 106 can be reflective. In some examples, the rigid surface can be specularly reflective (e.g., can have a relatively smooth reflective surface that causes relatively little scattering or diffusion when reflected). Suitable applications for the reflective rigid substrate 106 can include mirrors, such as vehicle rearview mirrors or side mirrors that can display information. Specifically, the specular reflective surface of the rigid substrate 106 can perform the function of reflecting light from the rear of the vehicle, and the sparse array of LEDs 102 can display information superimposed on the reflected light.

[0023] In some examples, rigid substrate 106 may be protective and / or decorative, such as a housing material for a mobile device such as a smartphone. Rigid substrate 106 may include other suitable optical properties, and also perform other suitable functions.

[0024] The rigid substrate 106 can be flat (e.g., substantially flat) or curved. The curved substrate can be used in a vehicle windshield, an augmented reality headset, a wearable device, or other suitable device. In some examples, the rigid substrate 106 is formed as a single unitary body. In other examples, the rigid substrate 106 can include multiple rigid substrate elements. For example, multiple rigid substrate elements can be used to create a folding display in a smartphone or other mobile device. As described below, a custom tool can support such a curved substrate during the lamination process.

[0025] The adhesive can adhere the rigid substrate 106 to the transparent flexible substrate 104. In some examples, the adhesive can be formed into an adhesive layer 108 so that the sparse array of LEDs 102 is located between the rigid substrate 106 and the transparent flexible substrate 104. Other suitable configurations can also be used. Suitable materials for the adhesive of the adhesive layer 108 can include silicone, epoxy silicone, acrylic film, epoxy film, etc.

[0026] In some examples, the adhesive of the adhesive layer 108 may be formed of a material having a refractive index that may match or substantially match the refractive index of the transparent flexible substrate 104 and / or the rigid substrate 106, or may be formed of a material having a refractive index that may be between the refractive indexes of the transparent flexible substrate 104 and the rigid substrate 106. Selecting the refractive index in this manner may reduce or eliminate reflections at the interface between the adhesive layer 108 and the transparent flexible substrate 104 and / or at the interface between the adhesive layer 108 and the rigid substrate 106. For example, the adhesive of the adhesive layer 108 may be formed of a material having a refractive index between about 1.4 and about 1.7. Using a refractive index in the range of about 1.4 to about 1.7 may reduce unwanted reflections between the adhesive layer 108 and the transparent flexible substrate 104 and unwanted reflections between the adhesive layer 108 and the rigid substrate 106. An optional thin film anti-reflective coating may also be used to help reduce or eliminate unwanted reflections at one or more interfaces between adjacent different materials or between a material and air.

[0027] In some examples, bonding layer 108 can fully encapsulate the sparse array of LEDs 102. By fully encapsulating the sparse array of LEDs 102, bonding layer 108 can protect the sparse array of LEDs 102 from environmental impacts and can form a smooth, unbroken interface with rigid substrate 106. To fully encapsulate the sparse array of LEDs 102, the adhesive of bonding layer 108 can have a sufficiently low resin viscosity so that the adhesive flows around LEDs 102 when deposited. In addition, to fully encapsulate the sparse array of LEDs 102, bonding layer 108 can be thick enough to fully cover the topography of the sparse array of LEDs 102.

[0028] Figure 2 It shows that it can include Figure 1 1 is a block diagram of an example of a visualization system 10 of a light source 100. The visualization system 10 may include a wearable housing 12, such as a headset or goggles. The housing 12 may mechanically support and accommodate the elements detailed below. In some examples, one or more of the elements detailed below may be included in one or more additional housings that may be separated from the wearable housing 12 and may be coupled to the wearable housing 12 wirelessly and / or via a wired connection. For example, a separate housing may reduce the weight of the wearable goggles, such as by including batteries, radios, and other elements. The housing 12 may include one or more batteries 14 that may power any or all of the elements detailed below. The housing 12 may include circuitry that may be electrically coupled to an external power source, such as a wall outlet, to charge the battery 14. The housing 12 may include one or more radios 16 to wirelessly communicate with a server or network via a suitable protocol, such as WiFi.

[0029] The visualization system 10 may include one or more sensors 18, such as optical sensors, audio sensors, tactile sensors, thermal sensors, gyroscope sensors, time-of-flight sensors, triangulation-based sensors, and the like. In some examples, one or more of these sensors may sense the location, position, and / or orientation of the user. In some examples, one or more of the sensors 18 may generate a sensor signal in response to the sensed location, position, and / or orientation. The sensor signal may include sensor data corresponding to the sensed location, position, and / or orientation. For example, the sensor data may include a depth map of the surrounding environment. In some examples, such as for an augmented reality system, one or more of the sensors 18 may capture real-time video images of the surrounding environment near the user.

[0030] The visualization system 10 may include one or more video generation processors 20. The one or more video generation processors 20 may receive scene data representing a three-dimensional scene from a server and / or a storage medium, such as a set of position coordinates of an object in the scene or a depth map of the scene. The one or more video generation processors 20 may receive one or more sensor signals from one or more sensors 18. In response to the scene data representing the surrounding environment and at least one sensor signal representing the location and / or orientation of the user relative to the surrounding environment, the one or more video generation processors 20 may generate at least one video signal corresponding to a view of the scene. In some examples, the one or more video generation processors 20 may generate two video signals, one for each eye of the user, the two video signals representing views of the scene from the perspective of the left eye and the right eye of the user, respectively. In some examples, the one or more video generation processors 20 may generate more than two video signals and combine the video signals to provide one video signal for both eyes, two video signals for both eyes, or other combinations.

[0031] The visualization system 10 may include one or more light sources 22 (such as Figure 1 Light source 100). Suitable light sources 22 may include light emitting diodes, monolithic light emitting diodes, multiple light emitting diodes, light emitting diode arrays, light emitting diode arrays disposed on a common substrate, segmented light emitting diodes disposed on a single substrate and having individually addressable and controllable (and / or controllable in groups and / or molecular sets) light emitting diode elements, micro light emitting diode (micro-LED) arrays, etc. In some examples, one or more of light sources 22 may include a sparse array of LEDs disposed on a transparent flexible substrate, and a rigid substrate adhered to the transparent flexible substrate using an adhesive layer, such that the sparse array of LEDs is located between the rigid substrate and the transparent flexible substrate.

[0032] The light emitting diode may be a white light emitting diode. For example, the white light emitting diode may emit excitation light, such as blue light or violet light. The white light emitting diode may include one or more phosphors that may absorb some or all of the excitation light and, in response, may emit phosphor light (such as yellow light) having a wavelength greater than the wavelength of the excitation light.

[0033] One or more light sources 22 may include light generating elements having different colors or wavelengths. For example, the light source may include a red light emitting diode that may emit red light, a green light emitting diode that may emit green light, and a blue light emitting diode that may emit blue light. The red light, green light, and blue light are combined in a particular ratio to produce any suitable color that is visually perceptible in the visible portion of the electromagnetic spectrum.

[0034] The visualization system 10 may include one or more modulators 24. The modulators 24 may be implemented in one of at least two configurations.

[0035] In a first configuration, the modulator 24 may include a circuit that can directly modulate the light source 22. For example, the light source 22 may include an array of light emitting diodes, and the modulator 24 may directly modulate the electrical power, voltage, and / or current directed to each light emitting diode in the array to form modulated light. The modulation may be performed in an analog manner and / or in a digital manner. In some examples, the light source 22 may include an array of red light emitting diodes, an array of green light emitting diodes, and an array of blue light emitting diodes, and the modulator 24 may directly modulate the red light emitting diodes, the green light emitting diodes, and the blue light emitting diodes to form modulated light to produce a particular image.

[0036] In a second configuration, the modulator 24 may include a modulation panel, such as a liquid crystal panel. The light source 22 may generate uniform illumination or near uniform illumination to illuminate the modulation panel. The modulation panel may include pixels. Each pixel may selectively attenuate a corresponding portion of the modulation panel area in response to an electrical modulation signal to form modulated light. In some examples, the modulator 24 may include a plurality of modulation panels that may modulate light of different colors. For example, the modulator 24 may include a red modulation panel that may attenuate red light from a red light source (such as a red light emitting diode), a green modulation panel that may attenuate green light from a green light source (such as a green light emitting diode), and a blue modulation panel that may attenuate blue light from a blue light source (such as a blue light emitting diode).

[0037] In some examples of the second configuration, the modulator 24 may receive uniform white light or nearly uniform white light from a white light source, such as a white light emitting diode. The modulation panel may include a wavelength selective filter on each pixel of the modulation panel. The panel pixels may be arranged in groups, such as three or four groups, where each group may form a pixel of a color image. For example, each group may include a panel pixel with a red filter, a panel pixel with a green filter, and a panel pixel with a blue filter. Other suitable configurations may also be used.

[0038] The visualization system 10 may include one or more modulation processors 26 that may receive a video signal (such as from one or more video generation processors 20) and in response may generate an electrical modulation signal. For configurations in which the modulator 24 directly modulates the light source 22, the electrical modulation signal may drive the light source 24. For configurations in which the modulator 24 includes a modulation panel, the electrical modulation signal may drive the modulation panel.

[0039] The visualization system 10 may include one or more beam combiners 28 (also referred to as beam splitters 28) that may combine light beams of different colors to form a single polychromatic light beam. For configurations in which the light source 22 may include a plurality of light emitting diodes of different colors, the visualization system 10 may include one or more wavelength-sensitive (e.g., dichroic) beam splitters 28 that may combine light of different colors to form a single polychromatic light beam.

[0040] The visualization system 10 can direct the modulated light toward the eyes of the observer in one of at least two configurations. In the first configuration, the visualization system 10 can be used as a projector and can include suitable projection optics 30 that can project the modulated light onto one or more screens 32. The screen 32 can be positioned at a suitable distance from the user's eyes. The visualization system 10 can optionally include one or more lenses 34 that can position a virtual image of the screen 32 at a suitable distance from the eyes, such as a close-focus distance, such as 500mm, 750mm, or another suitable distance. In some examples, the visualization system 10 can include a single screen 32 so that the modulated light can be directed toward both eyes of the user. In some examples, the visualization system 10 can include two screens 32 so that the modulated light from each screen 32 can be directed toward the corresponding eye of the user. In some examples, the visualization system 10 can include more than two screens 32. In a second configuration, the visualization system 10 can direct the modulated light directly into one or both eyes of the observer. For example, projection optics 30 may form an image on the retina of one eye of a user, or may form an image on each retina of both eyes of a user.

[0041] For some configurations of the augmented reality system, the visualization system 10 may include an at least partially transparent display so that the user can view the user's surroundings through the display. For such configurations, the augmented reality system may generate modulated light corresponding to an enhancement of the surroundings, rather than the surroundings themselves. For example, in the example of a retailer displaying chairs, the augmented reality system may direct modulated light corresponding to the chairs, rather than the rest of the room, toward the screen or toward the user's eyes.

[0042] Figure 3 and Figure 4 Shows Figure 1 1 and 2. Side views of light source 100 in various stages of assembly. Assembling light source 100 in this manner can help avoid air occlusions that can degrade the appearance and optical performance of the finished device. Other assembly techniques can also be used.

[0043] exist Figure 3 In the embodiment of the present invention, a sparse array of LEDs 102 has been arranged (e.g., mounted, grown, deposited, or otherwise formed) on a transparent flexible substrate 104. The transparent flexible substrate 104 has been removably mounted in or on a frame 302. A laminating tool 304 can advance the frame 302 toward an adhesive layer 306 that has been deposited on a support film 308. Alternatively, the laminating tool 304 can advance the adhesive layer 306 toward the frame 302, or advance the two toward each other. The sparse array of LEDs 102 will contact the adhesive layer 306 that has been deposited on the support film 308. The adhesive of the adhesive layer 306 can be in a solid form at room temperature. The adhesive has been applied to the support film 308 and has been covered by a cover film (not shown). A vacuum laminator having a temperature range that allows the adhesive to flow and conformally cover the topography of the LED array can laminate the adhesive layer 306 to the sparse array of LEDs 102 to encapsulate the sparse array of LEDs 102 in the adhesive layer 108. After lamination, the support film 308 may then be removed.

[0044] exist Figure 4 In the lamination tool 404 (optionally, with Figure 3 106) can advance the transparent flexible substrate 104 and the adhesive layer 108 toward the rigid substrate 106, wherein the sparse array of LEDs 102 is encapsulated in the adhesive layer 108. Alternatively, the lamination tool 404 can advance the rigid substrate 106 toward the transparent flexible substrate 104 and the adhesive layer 108, or toward each other. The lamination tool can laminate the adhesive layer 108 onto the rigid substrate 106, wherein the sparse array of LEDs 102 is encapsulated in the adhesive layer 108. After the adhesive layer 108 has been laminated to the rigid substrate 106, the entire layered structure can be subjected to temperature cycling to cure the adhesive.

[0045] In the above example, the transparent flexible substrate 104 has been laminated with the LED side facing the rigid substrate 106, so that the LED 102 is located between the two substrates and encapsulated by the adhesive. Alternatively, the transparent flexible substrate 104 can be laminated with the LED side facing away from the rigid substrate 106, so that the LED 102 is exposed, and the transparent flexible substrate 104 is located between the exposed LED 102 and the rigid substrate 106.

[0046] In some examples, additional components can be assembled onto the transparent flexible substrate, such as integrated circuits (ICs), micro ICs, or transistors for display backplanes. In addition, additional layers can be integrated into the device to form a capacitive or resistive touch screen.

[0047] Figure 5 A flowchart of an example of a method 500 for manufacturing a light source is shown. The method 500 may be used to manufacture Figure 1 The light source 100 or any other suitable light source can also be made by other methods. Figure 1 A light source 100 is provided.

[0048] At operation 502, a transparent flexible substrate is provided.

[0049] At operation 504, a sparse array of light emitting diodes (LEDs) is disposed on a transparent flexible substrate.

[0050] At operation 506 , the rigid substrate is adhered to the transparent flexible substrate such that the sparse array of LEDs is located between the rigid substrate and the transparent flexible substrate.

[0051] To further illustrate the systems and related methods disclosed herein, a non-limiting list of examples is provided below. Each of the following non-limiting examples may exist independently or may be combined with any one or more other examples in any arrangement or combination.

[0052] In Example 1, a light source may include: a transparent flexible substrate; a sparse array of light emitting diodes (LEDs) disposed on the transparent flexible substrate; and a rigid substrate adhered to the transparent flexible substrate such that the sparse array of LEDs is located between the rigid substrate and the transparent flexible substrate.

[0053] In Example 2, the light source according to Example 1 may optionally be configured such that the rigid substrate is adhered to the transparent flexible substrate using an adhesive layer, and the sparse array of LEDs is encapsulated in an adhesive of the adhesive layer.

[0054] In Example 3, the light source according to any one of Examples 1-2 can be optionally configured such that: the rigid substrate is substantially transparent; and the refractive index of the adhesive is between (including) the refractive index of the transparent flexible substrate and the refractive index of the rigid substrate.

[0055] In Example 4, the light source according to any of Examples 1-3 can optionally be configured such that the rigid substrate is substantially transparent.

[0056] In Example 5, the light source according to any of Examples 1-4 can optionally be configured such that the light emitting area of ​​the sparse array of LEDs is less than or equal to 5% of the surface area of ​​the sparse array.

[0057] In Example 6, the light source according to any of Examples 1-5 can optionally be configured such that a light emitting area of ​​the sparse array of LEDs is less than or equal to 1% of a surface area of ​​the sparse array.

[0058] In Example 7, the light source according to any of Examples 1-6 can optionally further include a transparent electrical trace configured to supply power to the LEDs in the sparse array of LEDs.

[0059] In Example 8, the light source according to any of Examples 1-7 can optionally be configured such that the sparse array of LEDs includes two or more LEDs that emit light at the same wavelength.

[0060] In Example 9, the light source according to any of Examples 1-8 can optionally be configured such that the sparse array of LEDs includes two or more LEDs that emit light at different wavelengths.

[0061] In Example 10, the light source according to any of Examples 1-9 can optionally be configured such that the rigid substrate is specularly reflective.

[0062] In Example 11, the light source according to any of Examples 1-10 can optionally be configured such that the rigid substrate is substantially flat.

[0063] In Example 12, the light source according to any of Examples 1-11 can optionally be configured such that the rigid substrate is curved.

[0064] In Example 13, the light source according to any of Examples 1-12 can optionally be configured such that the rigid substrate is a single integral component.

[0065] In Example 14, the light source according to any of Examples 1-13 can optionally be configured such that the rigid substrate includes a plurality of rigid substrate elements.

[0066] In Example 15, a method for manufacturing a light source may include: providing a transparent flexible substrate; disposing a sparse array of light emitting diodes (LEDs) on the transparent flexible substrate; and adhering a rigid substrate to the transparent flexible substrate such that the sparse array of LEDs is located between the rigid substrate and the transparent flexible substrate.

[0067] In Example 16, the method according to Example 15 can optionally be configured such that the rigid substrate is adhered to the transparent flexible substrate using an adhesive layer, and the sparse array of LEDs is encapsulated in an adhesive of the adhesive layer.

[0068] In Example 17, the method according to any one of Examples 15-16 can optionally be configured such that the refractive index of the adhesive is between (including) the refractive index of the transparent flexible substrate and the refractive index of the rigid substrate.

[0069] In Example 18, a light source may include: a transparent flexible substrate; a sparse array of light emitting diodes (LEDs) disposed on the transparent flexible substrate, a light emitting area of ​​the sparse array of LEDs being less than or equal to 10% of a surface area of ​​the sparse array; and a rigid substrate adhered to the transparent flexible substrate with an adhesive layer such that the sparse array of LEDs is encapsulated in an adhesive of the adhesive layer.

[0070] In Example 19, the light source according to Example 18 can optionally be configured such that the sparse array of LEDs includes two or more LEDs that emit light at the same wavelength.

[0071] In Example 20, the light source according to any of Examples 18-19 can optionally be configured such that the sparse array of LEDs includes two or more LEDs that emit light at different wavelengths.

[0072] Although only certain features of the system and method have been illustrated and described herein, many modifications and changes will be made by those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and changes. The method operations may be performed substantially simultaneously or in different orders.

Claims

1. A light source, comprising: Transparent flexible substrate; A sparse array of light emitting diodes (LEDs) disposed on a transparent flexible substrate; and A rigid substrate adhered to the transparent flexible substrate such that the sparse array of LEDs is located between the rigid substrate and the transparent flexible substrate.

2. The light source of claim 1, wherein the rigid substrate is adhered to the transparent flexible substrate using an adhesive layer, the sparse array of LEDs being encapsulated in an adhesive of the adhesive layer.

3. The light source according to claim 2, wherein: The rigid substrate is substantially transparent; and The adhesive has a refractive index between and including a refractive index of the transparent flexible substrate and a refractive index of the rigid substrate. The light source of claim 1 , wherein the rigid substrate is substantially transparent.

5. The light source of claim 1, wherein the light emitting area of ​​the sparse array of LEDs is less than or equal to 5% of the surface area of ​​the sparse array.

6. The light source of claim 1, wherein the light emitting area of ​​the sparse array of LEDs is less than or equal to 1% of the surface area of ​​the sparse array.

7. The light source of claim 1, further comprising transparent electrical traces configured to power LEDs in the sparse array of LEDs.

8. The light source of claim 1, wherein the sparse array of LEDs comprises two or more LEDs that emit light at the same wavelength.

9. The light source of claim 1, wherein the sparse array of LEDs comprises two or more LEDs that emit light at different wavelengths.

10. The light source of claim 1, wherein the rigid substrate is specularly reflective.

11. The light source of claim 1 , wherein the rigid substrate is substantially planar.

12. The light source of claim 1, wherein the rigid substrate is curved.

13. The light source of claim 1, wherein the rigid substrate is a single unitary component.

14. The light source of claim 1, wherein the rigid substrate comprises a plurality of rigid substrate elements.

15. A method for manufacturing a light source, the method comprising: Providing a transparent flexible substrate; A sparse array of light emitting diodes (LEDs) is provided on a transparent flexible substrate; and The rigid substrate is adhered to the transparent flexible substrate such that the sparse array of LEDs is located between the rigid substrate and the transparent flexible substrate.

16. The method of claim 15, wherein the rigid substrate is adhered to the transparent flexible substrate using an adhesive layer, the sparse array of LEDs being encapsulated in an adhesive of the adhesive layer. 17 . The method of claim 16 , wherein the adhesive has a refractive index between, and including, the refractive index of the transparent flexible substrate and the refractive index of the rigid substrate.

18. A light source, comprising: Transparent flexible substrate; A sparse array of light emitting diodes (LEDs) disposed on a transparent flexible substrate, the light emitting area of ​​the sparse array of LEDs being less than or equal to 10% of the surface area of ​​the sparse array; and The rigid substrate is adhered to the transparent flexible substrate with an adhesive layer such that the sparse array of LEDs is encapsulated in the adhesive of the adhesive layer.

19. The light source of claim 18, wherein the sparse array of LEDs comprises two or more LEDs that emit light at the same wavelength.

20. The light source of claim 18, wherein the sparse array of LEDs comprises two or more LEDs that emit light at different wavelengths.

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