Improved phosphor-converted light emitting devices

Abstract

The phosphor layer is attached to the LED with increased accuracy. In particular, the phosphor ceramic is attached to the LED with glue. During the attachment process, the glue must be hardened and / or cured. The phosphor ceramic includes a cap that contains glue in the cap when the glue hardens and / or is cured so that the phosphor ceramic is correctly aligned on the LED. The cover also improves light extraction by capturing light emitted from the side of the LED.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 356,819, filed on June 29, 2022, which is incorporated by reference in its entirety into this application. Technical Field

[0003] The present disclosure generally relates to LEDs, pcLEDs, LED arrays and pcLED arrays, light sources including LEDs, pcLEDs, LED arrays or pcLED arrays, and displays including LEDs or pcLED arrays. In particular, the present disclosure relates to methods and devices for integrating phosphors into semiconductor light emitting diodes. Background Art

[0004] Semiconductor light emitting diodes and laser diodes (collectively referred to herein as "LEDs") are among the most efficient light sources currently available. The emission spectrum of an LED typically exhibits a single narrow peak at a wavelength determined by the structure of the device and the composition of the semiconductor material from which it is constructed. By appropriately selecting the device structure and material system, an LED can be designed to operate at ultraviolet, visible, or infrared wavelengths.

[0005] The LED can be combined with one or more wavelength conversion materials (generally referred to herein as "phosphors") that absorb light emitted by the LED and emit longer wavelength light in response. For such a phosphor-converted LED ("pcLED"), the fraction of light emitted by the LED that is absorbed by the phosphor depends on the amount of phosphor material in the optical path of the light emitted by the LED, for example, on the concentration of phosphor material in a phosphor layer disposed on or around the LED and the thickness of the layer. The phosphor-converted LED can be designed so that all light emitted by the LED is absorbed by one or more phosphors, in which case the emission from the pcLED is entirely from the phosphor. In this case, for example, the phosphor can be selected to emit light in a narrow spectral region that is not directly and efficiently generated by the LED. Alternatively, the pcLED can be designed so that only a portion of the light emitted by the LED is absorbed by the phosphor, in which case the emission from the pcLED is a mixture of light emitted by the LED and light emitted by the phosphor. By appropriately selecting the LED, phosphor, and phosphor composition, such a pcLED can be designed to emit, for example, white light having a desired color temperature and desired color rendering properties.

[0006] Technical and commercial applications of LEDs and pcLEDs include use in displays, matrices, and light engines, including: automotive adaptive headlights, augmented reality (AR) displays, virtual reality (VR) displays, mixed reality (MR) displays, smart glasses, and displays for mobile phones, smart watches, monitors, and televisions, as well as flash lighting for cameras in mobile phones. For example, the backlighting of liquid crystal displays typically employs pcLEDs that include a combination of green and red phosphors. Individual LEDs or pcLEDs in these architectures can have an area of ​​a few square millimeters to a few square micrometers (microLEDs).

[0007] One specific type of wavelength conversion material is phosphor ceramic. Phosphor ceramics are widely used in the LED industry because of their high quantum efficiency light conversion and excellent thermal properties. The most common way to attach phosphor ceramics to LEDs is to use glue. However, due to unpredictable tension in the glue during the glue softening process, the placement of the phosphor ceramic on the LED die can be imprecise. This is undesirable from the standpoint of correctly centering the phosphor ceramic over the LED die. Furthermore, the imprecise gluing process means that the structure of the phosphor ceramic is limited to ceramics that are not offset from the die, which limits the type of devices that can be formed. Finally, light can escape from the sides of the LED die, which can result in light loss and reduce the overall efficiency of the device as a whole. Summary of the invention

[0008] Embodiments of the present invention include methods and devices for attaching phosphors to LEDs with increased precision, particularly having a cover containing glue in the phosphor ceramic during the attachment process so that when the glue hardens and / or is cured, it is properly aligned on the LED. The cover may also at least partially cover the sides of the LED, thereby reducing light losses, thereby increasing the efficiency of the light emitting device.

[0009] Embodiments of the present invention may be implemented in any application for general lighting, especially any application with high temperature and high power LEDs. In particular, embodiments of the present invention are suitable for use in motor vehicle headlights.

[0010] Additional aspects and advantages of the present disclosure will be readily apparent to those skilled in the art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be appreciated, the present disclosure is capable of other and different embodiments, and its several details are capable of modification in various obvious respects, all without departing from the present disclosure. Therefore, the drawings and descriptions are to be regarded as illustrative in nature, and not restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic cross-sectional view of an example pcLED is shown.

[0012] Figure 2A and Figure 2B A schematic cross-sectional view and a top view of a pcLED array are shown, respectively.

[0013] Figure 3A shows a schematic top view of an electronic board on which a pcLED array may be mounted, and Figure 3B Similarly, the installation Figure 3A pcLED array on an electronic board.

[0014] Figure 4A A schematic cross-sectional view of a pcLED array arranged relative to a waveguide and projection lens is shown. Figure 4B shows the difference between the case without waveguide and Figure 4A The arrangement is similar to the arrangement of .

[0015] Figure 5 An example camera flash system is schematically shown.

[0016] Figure 6 An example display (e.g., AR / VR / MR) system is schematically illustrated.

[0017] Figure 7 A cross-sectional view of an LED having a phosphor ceramic with a cap including a glue structure is shown.

[0018] Figure 8 A cross-sectional view of an LED having a phosphor ceramic with a cap at least partially comprising a glue structure extending down the sidewalls of the LED is shown.

[0019] Fig. 9 A cross-sectional view of an LED having a phosphor ceramic with a cap including a glue structure extending completely down the sidewalls of the LED is shown.

[0020] Fig.10 A cross-sectional view of an LED having an offset phosphor ceramic with a cap including a glue structure is shown.

[0021] Fig.11 A cross-sectional view of an LED array having phosphor ceramics, each having a cover including a glue structure, is shown.

[0022] Fig.12 A cross-sectional view of an LED array having a continuous phosphor ceramic with a cover including a glue structure is shown.

[0023] Fig.13A plan view of an LED having a phosphor ceramic with a cover including a glue structure is shown. DETAILED DESCRIPTION

[0024] The following detailed description should be read with reference to the accompanying drawings, wherein the same reference numerals refer to similar elements throughout the different figures. The drawings, which are not necessarily to scale, depict selective embodiments and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the invention by way of example, not by way of limitation.

[0025] Figure 1 An example of an individual pcLED 100 is shown, which includes a light emitting semiconductor diode (LED) structure 102 disposed on a substrate 104, and a phosphor layer 106 (also referred to herein as a wavelength conversion structure) disposed on the LED. The light emitting semiconductor diode structure 102 generally includes an active region disposed between an n-type layer and a p-type layer. Application of a suitable forward bias voltage to the diode structure results in emission of light from the active region. The wavelength of the emitted light is determined by the composition and structure of the active region.

[0026] For example, the LED may be a Group III nitride LED that emits ultraviolet, blue, green, or red light. LEDs formed from any other suitable material system and emitting any other suitable wavelength of light may also be used. Other suitable material systems may include, for example, Group III phosphide materials, Group III arsenide materials, and Group II-IV materials.

[0027] Any suitable phosphor material may be used, depending on the desired optical output and color specifications for the pcLED.The phosphor layer may, for example, comprise phosphor particles dispersed in or bonded to one another with a binder material, or may be or comprise a sintered ceramic phosphor plate.

[0028] Figure 2A-2B A cross-sectional view and a top view are shown, respectively, of an array 200 of pcLEDs 100 including a phosphor layer 106 disposed on a substrate 202. Such an array may include any suitable number of pcLEDs arranged in any suitable manner. In the illustrated example, the array is depicted as being monolithically formed on a shared substrate, but alternatively, the pcLED array may be formed of individual mechanically separated pcLEDs disposed on a substrate. The substrate 202 may optionally include CMOS circuitry for driving the LEDs, and may be formed of any suitable material.

[0029] although Figure 2A-2BA three-by-three array of nine pcLEDs is shown, but such an array may include, for example, tens, hundreds, or thousands of LEDs. The width (e.g., side length) of each LED in the plane of the array may be, for example, less than or equal to 1 millimeter (mm), less than or equal to 500 microns, less than or equal to 100 microns, or less than or equal to 50 microns. The LEDs in such an array may be separated from each other by streets or lanes having a width in the plane of the array of, for example, hundreds of microns, less than or equal to 100 microns, less than or equal to 50 microns, less than or equal to 10 microns, or less than or equal to 5 microns.

[0030] LEDs having a dimension in the plane of the array (eg, a side length) less than or equal to about 50 microns are generally referred to as micro-LEDs, and an array of such micro-LEDs may be referred to as a micro-LED array.

[0031] Although the illustrated examples show rectangular LEDs or pcLEDs arranged in a symmetrical matrix, the LEDs or pcLEDs and arrays may have any suitable shape or arrangement and need not all be the same shape or size. For example, LEDs or pcLEDs located in the center portion of the array may be larger than LEDs or pcLEDs located in the peripheral portion of the array. Alternatively, LEDs or pcLEDs located in the center portion of the array may be smaller than LEDs or pcLEDs located in the peripheral portion of the array.

[0032] In a pcLED array, all pcLEDs can be configured to emit substantially the same spectrum of light. Alternatively, the pcLED array can be a multicolor array, where different pcLEDs in the array can be configured to emit different spectra (colors) of light by employing different phosphor compositions. Similarly, in an array of direct emitting LEDs (i.e., without wavelength conversion by a phosphor), all LEDs in the array can be configured to emit substantially the same spectrum of light, or the array can be a multicolor array that includes LEDs configured to emit different colors of light.

[0033] Individual LEDs or pcLEDs in the array may be individually operable (addressable) and / or may be operable as part of a group or subset of (eg, adjacent) LEDs or pcLEDs in the array.

[0034] An LED or pcLED array, or portions of such an array, can be formed as a segmented monolithic structure in which the individual LEDs or pcLEDs are electrically isolated from each other by trenches and / or insulating materials, but the electrically isolated segments are still physically connected to each other through portions of the semiconductor structure.

[0035] Thus, the LED or pcLED array may be or include a monolithic multicolor matrix of individually operable LED or pcLED light emitters.The LEDs or pcLEDs in the monolithic array may, for example, be micro-LEDs as described above.

[0036] A single individually operable LED or pcLED or a group of adjacent such LEDs or pcLEDs may correspond to a single pixel (picture element) in a display. For example, a group of three adjacent individually operable LEDs or pcLEDs including a red emitter, a blue emitter, and a green emitter may correspond to a single color-tunable pixel in a display.

[0037] like Figure 3A-3B As shown in FIG. 1 , the LED or pcLED array 200 can be mounted on an electronic board 300 that includes a power and control module 302, a sensor module 304, and an attachment area 306. The power and control module 302 can receive power and control signals from an external source and signals from the sensor module 304, and the power and control module 302 controls the operation of the LED / pcLED based on these signals. The sensor module 304 can receive signals from any suitable sensor (e.g., from a temperature or light sensor). Alternatively, the array 200 can be mounted on a board (not shown) separate from the power and control module and the sensor module.

[0038] Each LED or pcLED may optionally be combined or arranged in combination with a lens or other optical element positioned adjacent to or disposed on the phosphor layer. Such optical elements, not shown in the figures, may be referred to as "primary optical elements". Figure 4A-4B As shown in , the array 200 (e.g., mounted on an electronic board 300) can be arranged in combination with secondary optical elements (such as waveguides, lenses, or both) for use in the intended application. Figure 4A In FIG. 4 , light emitted by pcLED 100 is collected by waveguide 402 and directed to projection lens 404. For example, projection lens 404 may be a Fresnel lens. This arrangement may be suitable for use, for example, in a motor vehicle headlight. Figure 4B In the embodiment of the present invention, the light emitted by the pcLED 100 is collected directly by the projection lens 404 without the use of an intervening waveguide. This arrangement may be particularly suitable when the LEDs or pcLEDs can be spaced sufficiently close to each other, and may also be used in automotive headlights and camera flash applications. For example, micro LED display applications may use a method similar to Figure 4A-4B An optical arrangement of the optical arrangement depicted in .

[0039] In another example arrangement, a center block of LEDs or pcLEDs in an array may be associated with a single common (shared) optic, and edge LEDs or pcLEDs in the array located at the periphery of the center block are each associated with a corresponding individual optic.

[0040] In general, any suitable arrangement of optical elements may be used in combination with the LED arrays and pcLED arrays described herein, depending on the desired application.

[0041] LED arrays and pcLED arrays as described herein can be used in applications that require or benefit from fine-grained intensity, spatial, and temporal control of light distribution. These applications can include, but are not limited to, precise special patterning of emitted light from individual LEDs or pcLEDs or from groups (e.g., blocks) of LEDs or pcLEDs. Depending on the application, the emitted light can be spectrally distinct, adaptive over time, and / or environmentally responsive. Such arrays can provide pre-programmed light distributions in various intensity, spatial, or temporal patterns. The emitted light can be based at least in part on received sensor data and can be used for optical wireless communications. The associated electronics and optics can be distinct at the individual LED / pcLED, group, or device level.

[0042] An array of independently operable LEDs or pcLEDs can be used in conjunction with a lens, a lens system, or other optical devices or optical systems (e.g., as described above) to provide lighting suitable for a particular purpose. For example, in operation, such an adaptive lighting system can provide lighting that changes color and / or intensity across the illuminated scene or object, and / or aims at a desired direction. The beam focusing or steering of the light emitted by the LED or pcLED array can be performed electronically by activating the LEDs or pcLEDs in groups of different sizes or activating the LEDs or pcLEDs in sequence to allow dynamic adjustment of the beam shape and / or direction without moving the optical device or changing the focus of the lens in the lighting device. The controller can be configured to receive data indicating the position and color characteristics of an object or person in the scene, and based on this information, control the LEDs or pcLEDs in the array to provide lighting suitable for the scene. Such data can be provided by, for example, an image sensor, an optical (e.g., laser scanning) sensor, or a non-optical (e.g., millimeter wave radar) sensor. Such adaptive lighting is increasingly important for motor vehicles (e.g., adaptive headlights), mobile device cameras (e.g., adaptive flash), VR and AR applications (such as those described below).

[0043] Figure 5An example camera flash system 500 including an LED or pcLED array and a lens system 502 is schematically shown, which can be or include an adaptive lighting system as described above, in which the LEDs or pcLEDs in the array can be individually operable. In operation of the camera flash system, illumination from some or all of the LEDs or pcLEDs in the array and lens system 502 can be adjusted (disabled, operated at full intensity, or operated at intermediate intensities). As described above, the array can be a monolithic array, or include one or more monolithic arrays. As described above, the array can be a micro-LED array.

[0044] The flash system 500 also includes an LED driver 506 controlled by a controller 504, such as a microprocessor. The controller 504 may also be coupled to a camera 507 and a sensor 508, and operate according to instructions and profiles stored in a memory 510. The camera 507 and the LED or pcLED array and lens system 502 may be controlled by the controller 504, for example, to match the illumination provided by the system 502 (i.e., the field of view of the illumination system) to the field of view of the camera 507, or to otherwise adapt the illumination provided by the system 502 to the scene viewed by the camera as described above. The sensor 508 may include, for example, a position sensor (e.g., a gyroscope and / or accelerometer) and / or other sensors that may be used to determine the position and orientation of the system 500.

[0045] Figure 6 An example display (e.g., AR / VR / MR) system 600 is schematically shown, which includes an array 610 of individually operable LEDs or pcLEDs, a display 620, a light array controller 630, a sensor system 640, and a system controller 650. As described above, the array 610 can be a monolithic array, or include one or more monolithic arrays. The array can be monochrome. Alternatively, the array can be a multi-color array, in which different LEDs or pcLEDs in the array are configured to emit light of different colors, as described above. Thus, the array can be or include a monolithic multi-color matrix of individually operable LED or pcLED light emitters, which can be, for example, micro-LEDs as described above. A single individually operable LED or pcLED in the array or a group of adjacent such LEDs or pcLEDs can correspond to a single pixel (picture element) in the display. For example, a group of three individually operable adjacent LEDs or pcLEDs including a red emitter, a blue emitter, and a green emitter can correspond to a single color-adjustable pixel in the display. The array 610 can be used to project light in a graphic pattern or an object pattern, which can support an AR / VR / MR system.

[0046] Control inputs are provided to the sensor system 640, while power and user data inputs are provided to the system controller 650. In some embodiments, the modules included in the system 600 may be compactly arranged in a single structure, or one or more elements may be mounted separately and connected via wireless or wired communications. For example, the array 610, display 620, and sensor system 640 may be mounted on a headset or glasses, with the light array controller and / or system controller 650 mounted separately.

[0047] System 600 may incorporate a variety of optics (not shown) to couple light emitted by array 610 into display 620. Any suitable optics may be used for this purpose.

[0048] Sensor system 640 may include, for example: external sensors to monitor the environment, such as cameras, depth sensors, or audio sensors; and internal sensors to monitor the position of the AR / VR / MR headset, such as accelerometers or two-axis or three-axis gyroscopes. Other sensors may include, but are not limited to, air pressure, strain sensors, temperature sensors, or any other suitable sensor required for local or remote environmental monitoring. In some embodiments, control inputs may include detected touches or taps, gesture inputs, or controls based on the position of the headset or display.

[0049] In response to data from the sensor system 640, the system controller 650 can send images or instructions to the light array controller 630. Changes or modifications to the images or instructions can also be made through user data input or automatic data input as needed. User data input can include, but is not limited to, data input provided by audio commands, tactile feedback, eye or pupil positioning, or a connected keyboard, mouse, or game controller.

[0050] The device as described above may include a reflective side coating or an absorptive side coating on the light emitting elements. The side coating optically isolates adjacent light emitting elements, thereby reducing crosstalk and increasing contrast between adjacent light emitting elements.

[0051] The phosphor layer used in the above devices may be a phosphor ceramic. Phosphor ceramics are particularly suitable for high temperature and high power LEDs due to their resilience, which allows them to withstand use with certain LEDs without the potential for optical degradation that other phosphor materials may experience.

[0052] Typically, the ceramic phosphor is attached to the die by a glue layer. The placement accuracy of the ceramic over the die is set by the tension created by the softening of the glue during the curing process. Therefore, the placement accuracy is completely dependent on self-alignment, which makes it an imprecise process that depends on many factors, such as glue viscosity, amount of glue dispensed, etc. In addition, due to the self-alignment forces, the ceramic cannot be offset relative to the die (a configuration that may be useful for specific applications). When placed on the LED die, the phosphor only covers the top of the LED, leaving a large surface (where light can escape and be lost) and reducing the efficiency of the LED.

[0053] Figure 7A light emitting device 700 is shown. The light emitting device 700 includes a phosphor structure 710 having a cover 740, a glue structure 720, and an LED 730. The LED 730 may be a chip scale package (CSP) and may be attached to a contact 770. The phosphor structure 710 may be a phosphor ceramic structure. The phosphor ceramic structure may be manufactured by various processes such as sintering or hot pressing phosphor powders together to form a phosphor ceramic structure. The phosphor structure 710 is attached to the LED 730 by the glue structure 720. The phosphor structure 710 has a cover 740 in which the glue structure 720 is disposed. The cover 740 may have a main attachment surface 750 facing the top light emitting surface 732 of the LED, and a cover sidewall 760 extending from the main attachment surface 750 (e.g., extending in a direction perpendicular to the plane of the main attachment surface 750). The plane of the main attachment surface 750 may extend parallel to the top light emitting surface 732 of the LED. The primary attachment surface 750 may have a larger area, a larger length, and / or a larger width (perpendicular to the length) than the area, length, and / or width of the top light emitting surface 732 of the LED 730. As a result, the phosphor structure 710 extends to overhang the LED sidewalls 734 of the LED 730. The cover sidewalls 760 of the cover 740 extend to vertically cover the LED sidewalls 734. When a path starting from the LED sidewall 734 and extending away from the LED 730 in a horizontal direction parallel to the plane of the primary attachment surface 750 intersects the cover sidewalls 760, a portion of the LED sidewall 734 is vertically covered. The cover sidewalls 760 of the cover may vertically cover at least a portion of the LED sidewall 734 while being spaced apart from the LED sidewall 734 without being in direct contact therewith. Alternatively, at least one of the cover sidewalls 760 may directly contact the LED sidewall 734. Because the cover sidewall 760 can at least partially vertically cover the LED sidewall 734, light propagating out of the LED (e.g., from the LED sidewall 734) can propagate into the cover sidewall 760 instead of into a reflective or absorptive side coating that may cause light loss. In this way, the cover increases the light efficiency of the light emitting device. The cover sidewall 760 may not cover the entire vertical height of the LED sidewall 734. For example, the cover sidewall 760 may cover less than most of the height of the LED sidewall 734, such as less than one-third of the height of the LED sidewall 734, such as less than one-quarter of the height of the LED sidewall 734.

[0054] Figure 7 A cross section of a light emitting device 700 is shown, wherein a cover side wall 760 surrounds the glue layer and part of the LED. Fig.13 Shows from Figure 7 A plan view of the light emitting device 700 observed in a vertical direction perpendicular to the plane of the LED top light emitting surface 730. Fig.13It is shown that the LED 730 can be completely surrounded by the cover sidewall 760 on all sides (e.g., on all four sides). In other words, each of the four LED sidewalls 734 is at least partially covered by one of the cover sidewalls 760, which is the same as described above with reference to FIG. Figure 7 Said Figure 7 The glue structure 720 can also be completely surrounded on four sides by the cover sidewalls 760. Thus, the cover 740 serves the purpose of containing the glue used to form the glue structure 720 so that it does not travel outside the cover 740 while the glue is setting or curing. This increases the alignment accuracy between the phosphor structure 710 and the LED 730 through the mechanical constraint of the cover. Fig.13 As shown, the cap 740 provides a boundary for the glue to properly center the phosphor ceramic over the LED in the xy plane and to limit rotation of the phosphor ceramic about the z-axis perpendicular to the xy plane.

[0055] A reflective or absorptive side coating 715 may be provided on the phosphor side surface 765 and the LED sidewall 734. Figure 7 , for ease of illustration, the side coating 715 is shown only on one side, and each side of the LED 730 and the phosphor structure 710 can be covered by the side coating 715 so that it surrounds the light emitting device 700. The side coating 715 can directly contact and / or conform to the phosphor side surface 765 and the LED side wall 734. The reflective or absorptive side coating 715 can prevent crosstalk between light emitting devices 700 arranged adjacent to each other, and / or reflect light that would otherwise escape the LED device back into the device to prevent light loss. The side coating 715 can be a thin film distributed Bragg reflector, scattering particles (such as TiO2 particles) in a binder used as a volume scatterer, or other similar coating. In Figure 7 , the side coating 715 is shown to leave an air gap 717 between the cover sidewall 760 and the LED sidewall 734. Alternatively, the side coating 715 can fill the remaining air gap 717 in the cover 740, so that there is no air gap 717, and / or the entire LED sidewall 734 is covered by the side coating 715.

[0056] The cover 740 may be referred to as a cavity in the phosphor structure. The cover may be formed by several techniques. For example, the cover may be formed by: 1) pressing a ceramic phosphor body into a mold having a cavity shape; 2) stamping or scratching the cavity shape into a flat body of the ceramic phosphor before sintering the ceramic phosphor; 3) etching the sintered ceramic phosphor at the cavity location; or 4) using laser ablation to create a cavity in a sintered ceramic phosphor structure.

[0057] The main attachment surface 750 of the cover 730 can be flat and can be designed to match the area of ​​the top light emitting surface 732 of the LED as closely as possible so that they have the same area or substantially the same area. Even so, due to tolerances, the main attachment surface 750 may be larger than the area of ​​the top light emitting surface 832 of the LED, for example, by about 10-20 microns. The phosphor structure 710 can have a phosphor light emitting surface 752 opposite the main attachment surface 750 of the cover 730, whose length and / or width is greater than the horizontal thickness of the corresponding side wall 760. That is, the phosphor light emitting surface 752 has a larger area than the main attachment surface 750. Based on the height of the side wall 760 in the horizontal direction, the phosphor structure 710 can be selected to have a phosphor light emitting surface 752 opposite the main attachment surface 750 of the cover 730. Figure 7 The height of the sidewall 760 obtained in the vertical direction in order to have sufficient mechanical integrity. In order to have sufficient mechanical integrity, the sidewall 760 with a higher height may need to have a greater thickness than the sidewall 760 with a lower height. The cover sidewall 760 can have a horizontal thickness of, for example, from 0.5-5 microns. The cover sidewall 760 can have a vertical height of, for example, from 20-120 microns. The phosphor structure 710 itself can have a vertical height of from 20-200 microns (e.g., from 40-150 microns).

[0058] In an embodiment of the present invention, the glue structure 720 is completely disposed in the cover 740. The glue structure 720 is in direct contact with the main attachment surface 750 and may be in direct contact with at least one of the side walls 760. Alternatively, the glue structure 720 is in direct contact only with the main attachment surface 750 and not with any of the cover side walls 760. In any case, the glue structure 720 is here completely disposed in the cover 740, which means that it is bounded on all sides by the side walls 760 and does not extend beyond the vertical height of any of the side walls 760 taken in a direction perpendicular to the plane of the main attachment surface 750. The vertical thickness of the glue structure 720 between the LED top emitting surface 732 and the main attachment surface 750 may be from 1-5 microns, such as from 2-3 microns.

[0059] The adhesive structure 720 can be a cured polysiloxane material, or epoxy resin. The process of attaching the phosphor structure with a cover to the LED can include placing a certain amount of glue on the main attachment surface 750 of the phosphor structure or on the LED top light-emitting surface 752 of the LED. The glue can be placed on the surface as a glue line, a droplet, or any other shape or volume. If the glue is placed on the main attachment surface 750 of the phosphor structure, the phosphor structure can be reversed so that the phosphor light-emitting surface 752 of the phosphor structure rests on a surface. Then, the LED is contacted with the glue so that it spreads over the LED top light-emitting surface 752 and the cover. If the glue is placed on the LED top light-emitting surface 752, the cover of the phosphor is contacted with the glue so that it spreads over the LED top light-emitting surface 752 and the cover. Subsequently, the applied glue is cured or otherwise hardened to form the adhesive structure 720.

[0060] Figure 8 An embodiment of the invention is shown in the form of a light emitting device 800 having a phosphor structure 810, a glue structure 820 and an LED 830. In the vertical direction, a portion of the glue structure 820 farthest from the main attachment surface 850 extends beyond the cover sidewall 860 to partially cover the LED sidewall 734 vertically. Figure 8 The glue structure 820 is shown to vertically cover the LED sidewall 834 to a greater extent than the cover sidewall 860. Alternatively, the glue structure 820 can vertically cover the LED sidewall 734 to a lesser extent than the cover sidewall 860. In any case, at least a majority of the glue structure 820 is completely disposed in the cover. However, a portion of the glue structure 820 is disposed outside the cover, that is, vertically beyond the cover sidewall 860. Some of this portion of the glue structure 820 can also be horizontally disposed beyond the area of ​​the main attachment surface 850. As a result, a portion of the bottom surface 864 of the cover sidewall 860 can be in direct contact with the glue structure 820. The bottom surface 864 of the cover sidewall 860 can be perpendicular to the inner side surface 862 of the cover sidewall 864 and parallel to the main attachment surface 850 of the cover. The area of ​​the bottom surface 864 plus the area of ​​the main attachment surface 850 can be equal to or substantially equal to the area of ​​the phosphor light emitting surface 852.

[0061] When the glue structure 820 extends vertically beyond the cover sidewall 860, the entire inner surface 862 of the cover sidewall 860 is in direct contact with the glue structure 820. As a result, the entire volume of the cover is filled with the glue structure 820 and (at least portions of) the LEDs 830.

[0062] The glue structure 820 extending to vertically cover the LED sidewall 834 can help with light extraction, especially where the wings extend beyond the cover to cover additional portions of the LED. When light is emitted through the LED sidewall 834, it may propagate into the reflective or absorptive side coating, which may result in light loss. Alternatively, if it propagates into the glue structure 820, it can be directed to the phosphor ceramic without suffering much light loss. In this way, the light efficiency of the device is increased.

[0063] Fig. 9 An embodiment of the present invention in the form of a light emitting device 900 is shown, which has a phosphor structure 910, a glue structure 920, and an LED 930. In the vertical direction, the glue structure 920 can extend to completely vertically cover or substantially completely vertically cover the LED sidewall 934. The cover sidewall 960 can also extend to completely vertically cover or substantially completely vertically cover the LED sidewall 934. Therefore, the cover sidewall 960 can completely vertically cover or substantially completely vertically cover the glue structure 920. The cover 940 can completely contain or substantially completely contain the entire LED 930 and the glue structure 920. That is, any part or substantially any part of the LED 930 and the glue structure 920 may not extend vertically beyond the bottom surface 964. In other words, the glue bottom surface 924 and the LED bottom surface 944 can be flush or substantially flush with each other and flush or substantially flush with the bottom surface 964 of the cover sidewall 960. The bottom surface 964 of the cover sidewall 960 can be adjacent to but not directly contact any part of the glue structure 920.

[0064] The vertical height of the cover sidewall 960 may be equal to the vertical height of the glue structure 920. The vertical height of the glue structure 920 may be greater than the vertical height of the LED 930. The glue structure 920 may completely horizontally surround the LED 930, and the cover sidewall 960 may completely horizontally surround both the LED 930 and the glue structure 920.

[0065] Fig.10An embodiment of the present invention in the form of a light emitting device 1000 is shown, which has a phosphor structure 1010, a glue structure 1020 and an LED 1030. The phosphor structure 1010 has an offset structure above the LED 1030. That is, the phosphor structure 1010 is asymmetrically arranged above the LED 1030. The offset phosphor ceramic can produce an asymmetrical emission profile with more light on one side of the device, which can simplify the primary and secondary optics used in conjunction with the light emitting device because they do not have to bend the light as much to give the final light beam its desired shape. The phosphor structure 1010 can be conceptually divided: a first portion 1091 of the phosphor structure 1010 is arranged directly above the top light emitting surface 1032 of the LED, and a second portion 1092 of the phosphor structure 1010 is arranged adjacent to the leftmost side wall 1034 of the LED ( Fig.10 ), and the third portion 1093 of the phosphor structure 1010 is disposed adjacent to the rightmost side wall 1034 of the LED ( Fig.10 on the right side of the page). Fig.10 The portions are shown divided by an imaginary dashed line. The second portion 1092 of the phosphor structure 1010 includes more phosphor structure 1010 (e.g., more volume) than the third portion 1093 of the phosphor structure 1010. The second portion 1092 can have the same (maximum) vertical thickness as the third portion 1093, but can have an area of ​​the phosphor light emitting surface 1052 that is larger than the area of ​​the phosphor light emitting surface 1052 in the third portion 1091. The second portion 1092 can have the same, smaller, or larger volume of the phosphor structure 1010 as the first portion 1091. The third portion 1093 can have a smaller volume of the phosphor structure 1010 than the first portion 1091. The second portion 1092 and the third portion 1093 can each include a respective cover sidewall 1060.

[0066] Another way to characterize the offset structure of the phosphor structure 1010 is that the phosphor structure 1010 has an asymmetrical shape and volume relative to a vertical and / or horizontal line extending through the center of the primary attachment surface 1050 and / or the center of the LED top emitting surface 1032. In addition, on one side of the cover ( Fig.10 The hood side wall 1060 on the left side of the hood is larger than that on the other side of the hood ( Fig.10 The cover side wall 1060 on the right side of the cover has a greater vertical thickness.

[0067] Without the cover 1040, if the phosphor structure 1010 is attached to the LED 1030 using glue that is then cured or otherwise solidified into the glue structure 1020, then the offset of the phosphor structure 1010 over the LED 1030 may result in misalignment of the phosphor structure 1010, particularly because the offset provides additional area for alignment of the hardened glue, thereby deviating from the phosphor structure without the offset. On the other hand, with the cover 1040, the self-alignment of the hardened glue can be limited to the cover area, thereby allowing the offset structure of the phosphor structure 1010 to be properly attached to the LED 1030.

[0068] Fig.11 An embodiment of the present invention is shown in the form of an array of light emitting devices 1100 on a substrate 1150, having a phosphor structure 1110, a glue structure 1120, and LEDs 1130. A cover 1140 reduces the gap between light emitting devices 1100 placed adjacent to each other. Small gaps are desirable to reduce dark areas in the emitting array. However, small gaps generally increase crosstalk between pixels in the array. The cover 1140 allows the devices to be placed close to each other, but reduces crosstalk between the LEDs and the phosphor. This is particularly true when the light emitting devices 1100 are covered with a reflective or absorptive side coating 1115. In Fig.11 For clarity, only one side coating 1115 is shown, but similar to Figure 7 As described above with respect to the side coatings in FIG. 1 , the side coating 1115 may cover any or all sides of each light emitting device 1100 .

[0069] Fig.12An embodiment of the present invention in the form of a light emitting device array 1200 is shown, which has a phosphor structure 1210, a glue structure 1220, and LEDs 1230. The phosphor structure 1210 is disposed over a plurality of LEDs 1230 and may be a continuous, integral structure over the LEDs and over the entire space between the LEDs. The phosphor structure 1210 has a plurality of covers 1240 designed to correspond to the position of each LED 1230. Adjacent covers 1240 may share a cover sidewall 1260 disposed therebetween. The shared cover sidewall 1260 may be thicker in the horizontal direction than the unshared cover sidewall 1260, for example, the cover sidewall 1260 on the outer portion of the array 1200 is not between at least two LEDs 1230 and / or is adjacent to only one LED 1230. Alternatively, the shared cover sidewall 1260 may have the same horizontal thickness as the unshared cover sidewall 1260. Individual, separate glue structures 1220 may be partially or fully contained in their respective covers 1240. Even when the glue structures 1220 are only partially contained in their respective covers 1240, they may not directly contact each other, and may directly contact only a respective one of the LEDs 1230 without contacting the other LEDs.

[0070] although Fig.12 The phosphor structure 1210 is shown disposed above two LEDs 1230 arranged along one dimension (e.g., along a horizontal line), but the phosphor structure 1210 can be disposed above multiple LEDs 1230 arranged in a two-dimensional arrangement (such as a 3×3, 7×7, or 9×9 LED array arranged in a rectangular grid) so that the phosphor structure 1210 has a 3×3, 7×7, or 9×9 cover array arranged in a rectangular grid to be disposed above the LEDs.

[0071] Multiple caps in the phosphor structure allow multiple LEDs to be attached to a single phosphor ceramic structure using glue, thereby preventing tilting of the phosphor structure over the array and other possible misalignments (eg, caused by height differences of the LEDs), especially when the glue softens.

[0072] The present disclosure is illustrative and not restrictive. In view of the present disclosure, further modifications will be clear to those skilled in the art and are intended to fall within the scope of the appended claims. For example, in the description of the above specific embodiments, although not explicitly stated, the elements may share the same or similar characteristics with other embodiments described in this specification.

Claims

1. A wavelength conversion structure, comprising: A phosphor ceramic structure comprising: a flat top surface, the plane of the top surface including a horizontal direction perpendicular to the vertical direction, a cover, which is opposite to the top surface and includes: an attachment surface parallel to the top surface and having a smaller area than the top surface, the attachment surface being flat and configured to be attached to the light emitting die via a glue layer, and a cover side wall extending away from the attachment surface and the top surface in the vertical direction and completely surrounding the attachment surface horizontally, A phosphor side surface extends vertically away from the top surface in the vertical direction to a bottom of the cover side wall opposite to the top surface, the phosphor side surface is flat and includes a top area adjacent to the top surface and a bottom area below the top area, and the bottom area is a part of the cover side wall. The wavelength conversion structure of claim 1 , the attachment surface having a rectangular area. The wavelength conversion structure of claim 2 , the attachment surface having a square area. The wavelength conversion structure according to claim 2 , wherein the cover side wall is composed of four cover side walls.

5. The wavelength conversion structure of claim 1, the phosphor ceramic structure having an asymmetric shape with respect to an imaginary line extending through a center of the cover.

6. The wavelength conversion structure of claim 5, one of the cover sidewalls having a greater horizontal thickness than another of the cover sidewalls.

7. The wavelength conversion structure of claim 1, wherein the cover is a first cover, and the phosphor ceramic structure further comprises a second cover adjacent to the first cover, the second cover comprising: a second attachment surface opposite the top surface, parallel to the top surface, and having a smaller area than the top surface, the attachment surface being flat and configured to be attached to a second light emitting die via a second glue layer, and A second cover side wall extends away from the second attachment surface and the top surface in the vertical direction and completely horizontally surrounds the second attachment surface, the second cover side wall including a bottom area of ​​the phosphor side surface.

8. The wavelength conversion structure of claim 1, wherein the cover sidewall and the second cover sidewall each comprise a shared sidewall having a different vertical thickness relative to the other of the cover sidewalls and the other of the second cover sidewalls.

9. A light emitting device, comprising: An LED having an LED light emitting surface including a horizontal direction perpendicular to a vertical direction, and an LED side surface extending away from the LED light emitting surface in the vertical direction; A phosphor ceramic structure disposed on the LED and comprising: top surface; a cover opposite to the top surface, the cover comprising: Attachment surface, and a hood sidewall extending away from the attachment surface and the top surface, and At least partially vertically covers the LED side surface, and a phosphor side surface extending away from the top surface to a bottom portion of the cover side wall opposite the top surface such that an area of ​​the phosphor side surface is a portion of the cover side wall; and A bonding structure is between the LED and the phosphor ceramic structure and combines the LED and the phosphor ceramic structure.

10. The light emitting device of claim 9, wherein the glue structure is fully contained in the cover. The light emitting device according to claim 9 , wherein the glue structure vertically extends beyond the cover sidewall. 12 . The light emitting device according to claim 9 , wherein the cover side wall completely vertically covers the LED side surface. The light emitting device according to claim 12 , wherein the glue structure completely vertically covers the LED side surface. The light emitting device according to claim 9 , wherein the cover side wall completely surrounds the LED horizontally.

15. The light emitting device of claim 10, wherein the phosphor ceramic structure has an asymmetric volume with respect to an imaginary center line extending through a center of the LED light emitting structure. The light emitting device according to claim 9 , wherein the cover side wall does not completely vertically cover the LED side surface.

17. An array of light emitting devices according to claim 9.

18. A light emitting device array, comprising: LEDs, each LED having an LED light emitting surface including a horizontal direction perpendicular to a vertical direction, and an LED side surface extending away from the LED light emitting surface in the vertical direction; a continuous phosphor ceramic structure disposed on the LED and comprising: top surface; shields adjacent to each other and opposite the top surface, the shields each comprising: Attachment surface, and a cover sidewall extending away from the attachment surface, and a phosphor side surface extending away from the top surface to a bottom portion of some of the cover side walls opposite the top surface such that an area of ​​the phosphor side surface is a portion of some of the cover side walls; and A respective glue structure is between respective ones of the LEDs and bonds respective ones of the LEDs to the phosphor ceramic structure.

19. The array of claim 18, wherein the respective glue structures are each contained within a respective one of the covers and are not in direct contact with each other.

20. The array of claim 18, wherein the cover sidewalls include shared cover sidewalls shared between adjacent covers, the shared cover sidewalls having a greater horizontal thickness than other of the cover sidewalls.

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