Transparent structure on pcled for increasing luminous flux

Abstract

A transparent structure for attachment to a phosphor-converted LED (pcLED) is disclosed. The transparent structure increases the total light output of the pcLED without further increasing the light emitting area of the phosphor layer (which becomes challenging and unreliable for thin phosphor layers).

Description

[0001] Cross - Reference to Related Applications This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 432,521, filed on Dec. 14, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0002] The present invention generally relates to LEDs, pcLEDs, light sources including LEDs and pcLEDs, and vehicle lamps including LEDs. Background Art

[0003] 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 materials of which it is composed. By appropriately selecting the device structure and material system, an LED can be designed to operate at ultraviolet, visible, or infrared wavelengths.

[0004] An LED can be combined with one or more wavelength - converting materials (generally referred to herein as "phosphors") that absorb the light emitted by the LED and in response emit light of a longer wavelength. For such phosphor - converted LEDs ("pcLEDs"), the fraction of the 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, e.g., on the concentration of the phosphor material in a phosphor layer disposed on or around the LED and the thickness of that layer. A phosphor - converted LED can be designed such that all of the light emitted by the LED is absorbed by one or more phosphors, in which case the emission from the pcLED comes entirely from the phosphors. In such a 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, a pcLED can be designed such 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 the light emitted by the LED and the light emitted by the phosphor. By appropriately selecting the LED, the phosphor, and the phosphor composition, such a pcLED can be designed to emit, for example, white light having a desired color temperature and desired color - rendering properties.

[0005] Inorganic LEDs and pcLEDs have been widely used in manufacturing different types of displays, matrices, and light engines, including: motor vehicle adaptive headlights, augmented reality (AR) displays, virtual reality (VR) displays, mixed reality (MR) displays (AR, VR, and MR systems are referred to as visualization systems herein), smart glasses, and displays for mobile phones, smart watches, monitors, and televisions, as well as flash illumination for cameras in mobile phones. Depending on the size of the matrix or display and its pixel requirements per inch, each LED or pcLED in these architectures can have an area ranging from a few square millimeters down to a few square micrometers (e.g., microLEDs). SUMMARY OF THE INVENTION

[0006] This specification discloses a phosphor-converted LED having an LED die, a wavelength-conversion structure disposed on the LED die, and a transparent structure disposed on the wavelength-conversion structure. The wavelength-conversion structure has a thickness less than 110 μm and has an overhang portion suspended above a substrate to which the LED die is mounted. The height of the transparent structure ranges from 10 μm to 500 μm. The transparent structure increases the total light flux emitted from the pcLED as compared to a pcLED without a transparent structure.

[0007] In some embodiments, the transparent structure has a substantially parallel base surface and a light-emitting surface. In some embodiments, the sidewalls connecting the base surface and the light-emitting surface are planar. In other embodiments, the sidewalls are curved. In other embodiments, the sidewalls have a corrugated shape. In some embodiments, the light-emitting surface of the transparent structure is textured. In some embodiments, the base surface of the transparent structure is textured.

[0008] In some embodiments, the base surface of the transparent structure is larger than the light-emitting area of the wavelength-conversion structure, thereby creating an overhang distance between the edge of the base surface and the edge of the light-emitting surface of the wavelength-conversion structure. The overhang distance ranges from 0 μm to 500 μm. In some embodiments, the overhang distance is less than 300 μm. In some embodiments, there is more than one overhang distance between the edge of the base surface and the edge of the light-emitting surface of the wavelength-conversion structure. In some embodiments, the overhang distance in a first direction ranges from 0 μm to 500 μm, while the overhang distance in a perpendicular second direction is 0 μm. In some embodiments, the overhang distance in the first direction and the overhang distance in the perpendicular second direction are different.

[0009] In some embodiments, the transparent structure is in the shape of a frustum of a pyramid. The angle θ between the sidewall of the frustum and the height of the frustum ranges from greater than 10° to less than 75°. In some embodiments, the angle θ is approximately 45°.

[0010] The transparent structure is made of a transparent material having a refractive index less than that of the wavelength conversion structure and greater than 1. In some embodiments, the transparent material is glass. In other embodiments, the transparent material is silicone.

[0011] The pcLEDs disclosed herein can be used in various devices and applications such as those listed in the background section above. In particular, the pcLEDs disclosed herein can be used in motor vehicle lighting applications where an increase in total luminous flux is beneficial. For example, the pcLEDs disclosed herein can be used in headlamps, tail lamps, turn signal indicators, and interior vehicle lighting and indicators.

[0012] These and other embodiments, features, and advantages of the present invention will become more apparent to those skilled in the art when the following more detailed description of the invention is taken in conjunction with the accompanying drawings, which are briefly described first. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic cross-sectional view of an exemplary pcLED is shown.

[0014] Figure 2A And Figure 2B Schematic cross-sectional and top views of a pcLED array are shown, respectively. Figure 2C A schematic top view of an LED wafer is shown from which an LED array such as Figure 2A And Figure 2B The LED arrays shown in can be formed.

[0015] Figure 3 A schematic top view of an electronic board on which an LED or pcLED array can be mounted is shown, and Figure 4 Similarly shown is a pcLED array mounted on the Figure 3 Electronic board.

[0016] Figure 5 An exemplary camera flash system is schematically shown.

[0017] Figure 6 An exemplary display system is schematically shown.

[0018] Figure 7 A block diagram of an exemplary visualization system is shown.

[0019] Figure 8 A schematic cross-sectional view of an exemplary pcLED is shown.

[0020] Figure 9 , Figure 10 And Figure 11Shows a schematic cross-sectional view of an example pcLED having a transparent structure.

[0021] Figure 12 and Figure 13 Shows a schematic plan view of an example pcLED having a transparent structure.

[0022] Figure 14 、 Figure 15 、 Figure 16 、 Figure 17 、 Figure 18 and Figure 19 Shows simulation results completed using Design of Experiments (DOE) in JMP software. Detailed Description

[0023] The following detailed description should be read with reference to the drawings, in which like reference numerals refer to like elements throughout the different figures. The drawings, which are not necessarily to scale, depict alternative embodiments and are not intended to limit the scope of the invention. The detailed description illustrates, by way of example, and not by way of limitation, the principles of the invention.

[0024] Figure 1 Shows an example of a single pcLED 100, which includes a light-emitting semiconductor diode (LED) structure 102 disposed on a substrate 104, and a phosphor layer 106 (which may also be 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. Applying a suitable forward bias across the diode structure causes light to be emitted from the active region. The wavelength of the emitted light is determined by the composition and structure of the active region.

[0025] For example, the LED can 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 can also be used. Other suitable material systems can include, for example, Group III phosphide materials, Group III arsenide materials, and II-IV group materials.

[0026] Any suitable phosphor material can be used, depending on the desired optical output and color specifications from the pcLED. The phosphor layer can, for example, include phosphor particles dispersed in a binder material or bonded to each other with a binder material, or can be or include a sintered ceramic phosphor plate.

[0027] Figure 2A - Figure 2BA cross-sectional view and a top view of an array 200 of pcLEDs 100 including a phosphor layer 106 disposed on a substrate 202 are shown, respectively. 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 formed monolithically on a shared substrate, but alternatively, an array of LEDs or pcLEDs may be formed of individually mechanically separated LEDs or pcLEDs. The substrate 202 may optionally include CMOS circuitry for driving the LEDs and may be formed of any suitable material.

[0028] Although Figure 2A - Figure 2B a three-by-three array of nine pcLEDs is shown, such an array may include, for example, dozens, hundreds, or thousands of LEDs or pcLEDs. The width (e.g., side length) of each LED or pcLED in the array plane may be, for example, less than or equal to 2 millimeters (mm), less than or equal to 1 mm, less than or equal to 500 micrometers, less than or equal to 100 micrometers, less than or equal to 50 micrometers, or less than or equal to 10 micrometers. The LEDs in such an array may be spaced apart from each other by a street or a lane having a width in the array plane of, for example, hundreds of micrometers, less than or equal to 100 micrometers, less than or equal to 50 micrometers, less than or equal to 10 micrometers, or less than or equal to 5 micrometers. Although the illustrated example shows rectangular LEDs or pcLEDs arranged in a symmetric matrix, the LEDs or pcLEDs and the array may have any suitable shape or arrangement and do not all need to have the same shape or size. For example, an LED or pcLED located in the central portion of the array may be larger than an LED or pcLED located in the peripheral portion of the array. Alternatively, an LED or pcLED located in the central portion of the array may be smaller than an LED or pcLED located in the peripheral portion of the array.

[0029] Figure 2C A schematic top view of a portion of an LED wafer 210 is shown from which an LED array such as Figure 2A and Figure 2B the LED arrays shown in Figure 2CAn enlarged 3×3 portion of the wafer is also shown. In an example wafer, individual LEDs or pcLEDs 111 having a side length (e.g., width) of W1 are arranged in a square matrix, where the center-to-center distance of adjacent LEDs or pcLEDs is D1 and is separated by a channel 113 having a width of W2. W1 can be, for example, less than or equal to 2 mm, less than or equal to 1 mm, less than or equal to 500 microns, less than or equal to 100 microns, less than or equal to 50 microns, or less than or equal to 10 microns. W2 can be, for example, several hundred 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. D1 = W1 + W2.

[0030] For example, an array can be formed by cutting the wafer 210 into individual LEDs or pcLEDs and arranging the die on a substrate. Alternatively, the array can be formed from the entire wafer 210 or by dividing the wafer 210 into smaller arrays of LEDs or pcLEDs.

[0031] LEDs or pcLEDs having dimensions (e.g., side length) in the array plane less than or equal to about 50 microns are generally referred to as microLEDs, and an array of such microLEDs can be referred to as a microLED array.

[0032] In a pcLED array, all pcLEDs can be configured to emit light having substantially the same spectrum. Alternatively, the pcLED array can be a multicolor array, where different pcLEDs in the array can be configured to emit light having different spectra (colors) by employing different phosphor compositions. Similarly, in an array of direct-emitting LEDs (i.e., not wavelength-converted by a phosphor), all LEDs in the array can be configured to emit light having substantially the same spectrum, or the array can be a multicolor array that includes LEDs configured to emit light of different colors.

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

[0034] An array of LEDs or pcLEDs, or portions of such an array, can be formed as a segmented monolithic structure, where individual LEDs or pcLEDs are electrically isolated or partially electrically isolated from each other by trenches and / or insulating materials, but the electrically isolated or partially electrically isolated segments remain physically connected to each other through other portions of the semiconductor structure. For example, in such a monolithic structure, an active region and a first semiconductor layer of a first conductivity type (n or p) on one side of the active region can be segmented, and a second unsegmented semiconductor layer of opposite conductivity type (p or n) is located on the side of the active region opposite the first semiconductor layer. The second semiconductor layer can then physically and electrically connect the segmented structures to each other on one side of the active region, where the segmented structures are otherwise electrically isolated from each other and can thus operate as separate LEDs individually.

[0035] Accordingly, an LED or pcLED array can be or include a monolithic multicolor matrix of individually operable LED or pcLED light emitters. The LEDs or pcLEDs in the monolithic array can be, for example, microLEDs as described above.

[0036] A single individually operable LED or pcLED or a group of adjacent such LEDs or pcLEDs can 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 can correspond to a single color-tunable pixel in a display.

[0037] As Figure 3 and Figure 4 shown in

[0038] Figure 5 An LED or pcLED array 200 can be mounted, for example, 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 as well as signals from the sensor module 304, and the power and control module 302 controls the operation of the LED / pcLEDs 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 separate board (not shown) from the power and control module and the sensor module.Schematically illustrated is an example camera flash system 500 that includes an LED or pcLED array and an optical (e.g., lens) system 502. The example camera flash system 500 may be or include an adaptive illumination system as described above, in which the LEDs or pcLEDs in the array may be individually operable or operable in groups. In operation of the camera flash system, the illumination from some or all of the LEDs or pcLEDs in the array and the optical system 502 may be adjusted (deactivated, operated at full intensity, or operated at an intermediate intensity). As described above, the array may be a monolithic array or include one or more monolithic arrays. As described above, the array may be a microLED array.

[0039] 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 in accordance with instructions and profiles stored in a memory 510. The camera 507 and the LED or pcLED array and the lens system 502 may be controlled by the controller 504 to, for example, 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 being viewed by the camera as described above. The sensor 508 may include, for example, a position sensor (e.g., a gyroscope and / or an accelerometer) and / or other sensors that may be used to determine the position and orientation of the system 500.

[0040] Figure 6FIG. 600 schematically shows an example display system 600, which includes an array 610 of individually operable or group-operable LEDs or pcLEDs, a display 620, a light-emitting 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 monochromatic. Alternatively, the array can be a multicolor array, where different LEDs or pcLEDs in the array are configured to emit different colors of light, as described above. Thus, the array can be or include a monolithic multicolor matrix of individually operable LED or pcLED light emitters, which can be, for example, microLEDs as described above. An 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-tunable pixel in the display. Similarly, to provide redundancy in the case of a defective LED or pcLED, a group of six individually operable adjacent LEDs or pcLEDs including two red emitters, two blue emitters, and two green emitters can correspond to a single color-tunable pixel in the display. The array 610 can be used to project light in a graphic pattern or an object pattern, which can support, for example, an AR / VR / MR system.

[0041] Sensor 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 can be compactly arranged in a single structure, or one or more elements can be separately mounted and connected via wireless or wired communication. For example, the array 610, the display 620, and the sensor system 640 can be mounted on a headset or glasses, where the light-emitting array controller and / or the system controller 650 are separately mounted.

[0042] The system 600 can incorporate a variety of optical devices (not shown) to couple the light emitted by the array 610 into the display 620. Any suitable optical device can be used for this purpose.

[0043] The sensor system 640 can include, for example: external sensors that monitor the environment, such as cameras, depth sensors, or audio sensors; and internal sensors that monitor the position of an AR / VR / MR headset, such as accelerometers or two-axis or three-axis gyroscopes. Other sensors can include, but are not limited to, barometric pressure, stress sensors, temperature sensors, or any other suitable sensors required for local or remote environmental monitoring. In some embodiments, the control inputs through the sensor system can include detected touches or taps, gesture inputs, or controls based on the position of the headset or the display.

[0044] In response to data from the sensor system 640, the system controller 650 may send an image or instructions to the light emitting array controller 630. Changes or modifications to the image or instructions may also be made via user data input or automated data input as needed. User data input may include, but is not limited to, data input provided by audio instructions, tactile feedback, eye or pupil positioning, or a connected keyboard, mouse, or game controller.

[0045] As described above, AR, VR, and MR systems can be more generally referred to as examples of visualization systems. In a virtual reality system, a display may present a view of a scene (such as a three-dimensional scene) to a user. The user may move within the scene, such as by repositioning the user's head or by walking. The virtual reality system may detect the user's movement and change the view of the scene to account for the movement. For example, when the user rotates the user's head, the system may present a view of the scene that changes in the direction of view to match the user's gaze. In this way, the virtual reality system can simulate the user's presence in a three-dimensional scene. Additionally, the virtual reality system may receive tactile sensory input, such as from a wearable position sensor, and may optionally provide tactile feedback to the user.

[0046] In an augmented reality system, a display may incorporate elements from the user's surrounding environment into the view of the scene. For example, an augmented reality system may add text captions and / or visual elements to the view of the user's surrounding environment. For example, a retailer may use an augmented reality system to show a user what a piece of furniture would look like in a room in the user's home by combining a visualization of the piece of furniture over a captured image of the user's surrounding environment. As the user walks around in the user's room, the visualization interprets the user's movement and changes the visualization of the furniture in a manner consistent with the movement. For example, the augmented reality system may place a virtual chair in the room. The user may stand in front of the virtual chair position in the room to view the front side of the chair. The user may move within the room to an area behind the virtual chair position to view the back side of the chair. In this way, the augmented reality system can add elements to a dynamic view of the user's surrounding environment.

[0047] Figure 7Shows a general block diagram of an example visualization system 710. The visualization system 710 can include a wearable housing 712, such as a headset or goggles. The housing 712 can mechanically support and house the elements detailed below. In some examples, one or more of the elements detailed below can be included in one or more additional housings that can be separate from the wearable housing 712 and coupled to the wearable housing 712 wirelessly and / or via a wired connection. For example, a separate housing can reduce the weight of the wearable goggles, such as by including a battery, radio, and other components. The housing 712 can include one or more batteries 714 that can power any or all of the elements detailed below. The housing 712 can include circuitry that can be electrically coupled to an external power source, such as a wall outlet, to charge the battery 714. The housing 712 can include one or more radios 716 to communicate wirelessly with a server or network via a suitable protocol, such as WiFi.

[0048] The visualization system 710 can include one or more sensors 718, such as optical sensors, audio sensors, tactile sensors, thermal sensors, gyroscopic sensors, time-of-flight sensors, triangulation-based sensors, and so on. In some examples, one or more sensors can sense a user's location, position, and / or orientation. In some examples, one or more sensors 718 can generate a sensor signal in response to the sensed location, position, and / or orientation. The sensor signal can include sensor data corresponding to the sensed location, position, and / or orientation. For example, the sensor data can include a depth map of the surrounding environment. In some examples, such as for an augmented reality system, one or more sensors 718 can capture real-time video images of the surrounding environment near the user.

[0049] The visualization system 710 may include one or more video generation processors 720. The one or more video generation processors 720 may receive scene data representing a three-dimensional scene, such as a set of position coordinates of objects in the scene or a depth map of the scene, from a server and / or a storage medium. The one or more video generation processors 720 may receive one or more sensor signals from one or more sensors 718. 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 720 may generate at least one video signal corresponding to a view of the scene. In some examples, the one or more video generation processors 720 may generate two video signals, one for each eye of the user, the two video signals respectively representing views of the scene seen from the perspectives of the user's left eye and right eye. In some examples, the one or more video generation processors 720 may generate more than two video signals and combine these video signals to provide one video signal for both eyes, two video signals for both eyes, or other combinations.

[0050] The visualization system 710 may include one or more light sources 722 that may provide light for a display of the visualization system 710. Suitable light sources 722 may include any of the LEDs, pcLEDs, LED arrays, and pcLED arrays discussed above, such as those discussed above with respect to the display system 600. The visualization system 710 may include one or more modulators 724. The modulator 724 may be implemented in at least one of two configurations.

[0051] In a first configuration, the modulator 724 may include circuitry that may directly modulate the light source 722. For example, the light source 722 may include an array of light-emitting diodes, and the modulator 724 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 a digital manner. In some examples, the light source 722 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 724 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 specific image.

[0052] In a second configuration, the modulator 724 can include a modulation panel, such as a liquid crystal panel. The light source 722 can generate uniform illumination or near-uniform illumination to illuminate the modulation panel. The modulation panel can include pixels. Each pixel can 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 724 can include multiple modulation panels that can modulate light of different colors. For example, the modulator 724 can include a red modulation panel that can attenuate red light from a red light source (such as a red light-emitting diode), a green modulation panel that can attenuate green light from a green light source (such as a green light-emitting diode), and a blue modulation panel that can attenuate blue light from a blue light source (such as a blue light-emitting diode).

[0053] In some examples of the second configuration, the modulator 724 can receive uniform white light or near-uniform white light from a white light source (such as a white light-emitting diode). The modulation panel can include wavelength-selective filters on each pixel of the modulation panel. The panel pixels can be arranged in groups (such as three or four groups), where each group can form a pixel of a color image. For example, each group can include panel pixels with a red filter, panel pixels with a green filter, and panel pixels with a blue filter. Other suitable configurations can also be used.

[0054] The visualization system 710 can include one or more modulation processors 726, which can receive video signals (such as from one or more video generation processors 720) and, in response, can generate electrical modulation signals. For configurations in which the modulator 724 directly modulates the light source 722, the electrical modulation signal can drive the light source 722. For configurations in which the modulator 724 includes a modulation panel, the electrical modulation signal can drive the modulation panel.

[0055] The visualization system 710 can include one or more beam combiners 728 (also referred to as beam splitters 728) that can combine different color beams to form a single multi-color beam. For configurations in which the light source 722 can include multiple light-emitting diodes of different colors, the visualization system 710 can include one or more wavelength-sensitive (e.g., dichroic) beam splitters 728 that can combine different colors of light to form a single multi-color beam.

[0056] The visualization system 710 can direct modulated light towards the observer's eyes in at least one of two configurations. In a first configuration, the visualization system 710 can function as a projector and can include suitable projection optics 730 that can project the modulated light onto one or more screens 732. The screen 732 can be positioned at a suitable distance from the user's eyes. The visualization system 710 can optionally include one or more lenses 734 that can position a virtual image of the screen 732 at a suitable distance from the eyes, such as a close-focus distance, such as 500 mm, 750 mm, or another suitable distance. In some examples, the visualization system 710 can include a single screen 732 such that the modulated light can be directed towards the user's binocular eyes. In some examples, the visualization system 710 can include two screens 732 such that the modulated light from each screen 732 can be directed towards the corresponding eye of the user. In some examples, the visualization system 710 can include more than two screens 732. In a second configuration, the visualization system 710 can direct the modulated light directly into one or both eyes of the observer. For example, the projection optics 730 can form an image on the retina of one eye of the user, or on the retina of each of the two eyes of the user.

[0057] For some configurations of the augmented reality system, the visualization system 710 can include at least a partially transparent display such that the user can view the user's surrounding environment through the display. For such a configuration, the augmented reality system can generate enhanced modulated light corresponding to the surrounding environment rather than the surrounding environment itself. For example, in an example where a retailer displays a chair, the augmented reality system can direct the modulated light corresponding to the chair rather than the rest of the room towards the screen or towards the user's eyes.

[0058] In many systems, an increase in the total light output ("total LOP") of an LED, pcLED, LED array, or pcLED array is desirable. Systems that may benefit from an increase in total LOP include motor vehicle lighting, which includes headlamps, tail lamps, signal indicator lamps, display lamps within a motor vehicle, camera flashes, etc. One way to increase the total LOP of an LED is to increase the light-emitting area ("LEA") of the phosphor layer, i.e., the wavelength-converting structure that contains the phosphor material. For a pcLED, the total LOP is proportional to the size of the wavelength-converting structure. Figure 8 A wavelength-converting structure 806 disposed on an LED die 805 (which includes a semiconductor diode structure) is shown. The LED die 805 is disposed on a substrate 801. The wavelength-converting structure 806 is attached to the LED die 805 using an adhesive 809. In Figure 8 , the LEA 807 of the wavelength-converting structure is larger than the LEA 808 of the LED die. As compared withFigure 1 Compared with the arrangement of the pcLED 100 shown in [reference], this arrangement increases the total LOP of the pcLED 800.

[0059] However, there are limitations to how much the LEA 807 of the wavelength conversion structure can be increased, especially when the wavelength conversion structure is thin (i.e., less than 110 μm thick). This is, for example, due to the protrusion 810 created by making the surface area of the wavelength conversion structure in contact with the LED die 805 larger than the LEA 808 of the LED die 805. The protrusion 810 of the wavelength conversion structure 806 is a projection of the wavelength conversion structure 806 beyond the sidewall 804 of the LED die 805, such that the protrusion 810 hangs over the substrate 801. For thin wavelength conversion structures (less than about 100 μm), it becomes challenging and unreliable to increase the LEA of the wavelength conversion structure by increasing the structural protrusion 810 because the structure may break due to insufficient support under the protrusion 810.

[0060] To further increase the total LOP of a pcLED in which the wavelength conversion structure is less than 110 μm thick, a transparent structure, typically in the shape of a frustum, is provided on top of the wavelength conversion structure, which helps extract more light from the pcLED while increasing the top LEA. The transparent structure is made of a transparent material having a refractive index less than that of the phosphor layer but greater than that of air (i.e., greater than 1). In some embodiments, the transparent structure is made of glass. In other embodiments, the transparent structure is made of silicone. The transparent structure can be attached to the wavelength conversion structure by a transparent adhesive (such as silicone epoxy or silicone).

[0061] In Figure 9 [figure], the transparent structure 901 is disposed on the wavelength conversion structure 806 to form the pcLED 900. In Figure 9The transparent structure 901 therein is in the shape of a frustum of a pyramid, where the base 902 faces the phosphor layer 806 and is in contact with the phosphor layer 806, and the base 903 is the light-emitting region of the pcLED. The base 903 is substantially parallel to the base 902. The transparent structure 901 has a height h between the bases 902 and 903 and an angle θ between the height h and the slant height L. The area of the base 903 is larger than the area of the base 902. In some embodiments, the area of the base 902 can be larger than the LEA 807 of the wavelength conversion structure 806, which creates a protrusion distance between the edge of the base 902 and the edge of the LEA 807. The portion of the transparent structure 901 covered by the protrusion distance hangs over the substrate 801. In some embodiments, there is nothing supporting the transparent structure 901 under the portion of the transparent structure between the edge of the base 902 and the edge of the LEA 807. In some embodiments, the base 902 has a textured surface. In some embodiments, the base 903 has a textured surface. The textured surface helps extract more light from the pcLED. In some embodiments, the surfaces of both the base 902 and the base 903 are textured. The height h can be between 10 μm and 500 μm. The angle θ can be between 10° and 75°. The protrusion distance can be between 0 μm and 300 μm. In some embodiments, the protrusion distance can be between 0 μm and 500 μm.

[0062] Figure 10 An alternative embodiment of the transparent structure 901 is shown, where the sidewalls of the transparent structure are curved instead of straight. In some embodiments, the shape of the curve can be circular. In some embodiments, the shape of the curve can be parabolic. The shape of the curve can be configured to direct light out through the LEA of the transparent structure.

[0063] Figure 11 An alternative embodiment of the transparent structure 901 is shown, where the sidewalls of the transparent structure are corrugated, i.e., the sidewalls have ridges or grooves or both. In some embodiments, the sidewalls can be corrugated in a sine wave shape. In some embodiments, the sidewalls can have a sawtooth corrugation shape.

[0064] The transparent structure 901 can be arranged on the wavelength conversion structure 806 in a symmetric manner. Figure 12 Shown is Figure 9 - Figure 11 a plan view of the pcLED 900. As Figure 12 shown, the transparent structure is arranged on the wavelength conversion structure in a symmetric manner such that the protrusion distance between the LEA 807 of the wavelength conversion structure and the base 902 of the transparent structure is equal on all four sides of the pcLED 900. Specifically, as Figure 12As shown, the two protrusion distances in the x-direction are equal and equal to the two protrusion distances in the y-direction. Additionally, the angle θ is equal in all four directions (i.e., the positive x-direction, the negative x-direction, the positive y-direction, and the negative y-direction).

[0065] Figure 13 shows Figure 9 - Figure 11 a plan view of the pcLED 900, where the protrusion distances and the angle θ are not equal in the x-direction and the y-direction. In Figure 13 , there is a certain positive protrusion distance in the positive x-direction and the negative x-direction, but there is no protrusion distance in the positive y-direction and the negative y-direction. In some embodiments, the protrusion distances in the positive x-direction and the negative x-direction are equal. Additionally, Figure 13 the transparent structure in

[0066] has a certain angle θ in the positive x-direction and the negative x-direction, but has no angle θ in the positive y-direction and the negative y-direction (i.e., the angle θ is substantially zero in these directions). The effect of having a certain protrusion distance and angle θ in the x-direction while having no protrusion distance and angle θ in the y-direction is that the pcLED 900 will emit more light in the x-direction than in the y-direction. Having the protrusion distance and angle θ increases the luminous flux emitted in these directions.

[0067] Figure 14 shows for a 1 mm 2 LED die and a 1.06×1.06 mm 2 wavelength conversion structure (i.e., an LED die with LEA of 1 mm 2 and a wavelength conversion structure with LEA of 1.06 mm 2 ). In this LED and wavelength conversion structure configuration, Figure 14It shows that the optimal angle θ is 75°, the optimal height is 500 μm, and the optimal protrusion distance is approximately 58 μm. Using these optimized parameters, the transparent structure is expected to increase the total luminous flux of the pcLED by approximately 7.7% compared to a pcLED without a transparent structure, where the prediction confidence interval for the total flux increase is between approximately 6.2% and approximately 9.3%. In Figure 14 - Figure 19 the shaded area in the chart shown in Figure 14 - Figure 19 represents the confidence interval. The desire in

[0068] Figure 15 shows the simulation results for a 1 mm 2 LED die and a 1.15×1.15 mm 2 wavelength conversion structure. Configuration of the LED and the wavelength conversion structure: The optimal angle θ is 75°, the optimal height is 500 μm, and the optimal protrusion distance is approximately 77 μm. Using these optimized parameters, the transparent structure is expected to increase the total luminous flux of the pcLED by approximately 6.3% compared to a pcLED without a transparent structure, where the confidence interval is between approximately 5% and 7.6%.

[0069] Figure 16 shows the simulation results for a 1 mm 2 LED die and a 1.06×1.06 mm 2 wavelength conversion structure, where the height of the transparent structure is fixed at 200 μm. With h fixed at 200 μm, the optimal angle θ is 75°, and the optimal protrusion distance is approximately 200 μm. Using these optimized parameters, the transparent structure is expected to increase the total luminous flux of the pcLED by approximately 4.9% compared to a pcLED without a transparent structure, where the confidence interval is between approximately 3.3% and 6.4%.

[0070] Figure 17 shows the simulation results for a 1 mm 2 LED die and a 1.15×1.15 mm 2 wavelength conversion structure, where the height of the transparent structure is fixed at 200 μm. With h fixed at 200 μm, the optimal angle θ is 75°, and the optimal protrusion distance is approximately 77 μm. Using these optimized parameters, the transparent structure is expected to increase the total luminous flux of the pcLED by approximately 3.7% compared to a pcLED without a transparent structure, where the confidence interval is between approximately 2.4% and 5%.

[0071] Figure 18 shows the simulation results for a 1 mm 2 LED die and a 1.06×1.06 mm 2Simulation results of the wavelength conversion structure, where the angle θ of the transparent structure is fixed at approximately 45°. At an angle θ = 45°, the optimal height is approximately 454 μm, and the optimal protrusion distance is approximately 200 μm. Using these optimized parameters, the transparent structure is expected to increase the total luminous flux of the pcLED by approximately 5.5% compared to a pcLED without a transparent structure, with a confidence interval between approximately 4.2% and 7%.

[0072] Figure 19 Shows for a 1 mm 2 LED die and a 1.15×1.15 mm 2 Simulation results of the wavelength conversion structure, where the angle θ of the transparent structure is fixed at 45°. At an angle θ = 45°, the optimal height is approximately 443 μm, and the optimal protrusion distance is approximately 200 μm. Using these optimized parameters, the transparent structure is expected to increase the total luminous flux of the pcLED by approximately 4.4% compared to a pcLED without a transparent structure, with a confidence interval between approximately 3.2% and 5.7%.

[0073] This disclosure is illustrative and not restrictive. Given this disclosure, further modifications will be apparent to those skilled in the art and are intended to fall within the scope of the appended claims.

Claims

1. A pcLED, comprising: an LED die, which includes a light-emitting surface having a first area; a wavelength conversion structure, which includes a phosphor and a light-emitting surface having a second area larger than the first area, the wavelength conversion structure being disposed on the light-emitting surface of the LED die, the wavelength conversion structure having a thickness less than 110 μm; and a transparent structure, which includes a transparent material, the refractive index of which is less than the refractive index of the wavelength conversion structure and greater than 1, a base surface having a third area, and an oppositely positioned light-emitting surface, which has a fourth area larger than the third area and the second area, the transparent structure being disposed on the light-emitting surface of the wavelength conversion structure, wherein the base surface faces the wavelength conversion structure, and the transparent structure has a height less than 500 μm between the base surface and the light-emitting surface.

2. The pcLED according to claim 1, wherein the LED die is disposed on a substrate, and the wavelength conversion structure disposed on the light-emitting surface of the LED die creates a protruding portion of the wavelength conversion structure that protrudes above the substrate.

3. The pcLED according to claim 1, wherein the base surface and the light-emitting surface of the transparent structure are substantially parallel.

4. The pcLED according to claim 1, wherein the transparent structure includes sidewalls connecting the base surface and the light-emitting surface.

5. The pcLED according to claim 4, wherein the sidewalls have a corrugated shape.

6. The pcLED according to claim 4, wherein the sidewalls have a curved shape.

7. The pcLED according to claim 1, wherein the light-emitting surface of the transparent structure is textured.

8. The pcLED according to claim 1, wherein the base surface of the transparent structure is textured.

9. The pcLED according to claim 1, wherein the third area of the base surface is larger than the second area of the wavelength conversion structure, thereby creating a protruding distance between the edge of the base surface and the edge of the light-emitting surface of the wavelength conversion structure.

10. The pcLED according to claim 9, wherein the protruding distance is less than 300 μm.

11. A pcLED, comprising: an LED die, which includes a light-emitting surface having a first area; a wavelength conversion structure, which includes a phosphor and a light-emitting surface having a second area larger than the first area, the wavelength conversion structure being disposed on the light-emitting surface of the LED die, the wavelength conversion structure having a thickness less than 110 μm; and a transparent structure in the shape of a frustum of a pyramid, which includes a transparent material, the refractive index of which is less than the refractive index of the wavelength conversion structure and greater than 1, a first base surface having a third area, and a second base surface, which has a fourth area larger than the third area and the second area, The transparent structure is disposed on a light-emitting surface of the wavelength conversion structure, wherein the first substrate surface faces the wavelength conversion structure, and the transparent structure has a height of less than 500 μm between the first substrate surface and the second substrate surface.

12. The pcLED according to claim 11, wherein the LED die is disposed on a substrate, and the wavelength conversion structure disposed on a light-emitting surface of the LED die creates a protruding portion of the wavelength conversion structure that protrudes above the substrate.

13. The pcLED according to claim 11, wherein the second substrate surface of the transparent structure is textured.

14. The pcLED according to claim 11, wherein a third area of the substrate surface is larger than a second area of the wavelength conversion structure, thereby creating a first protrusion distance between a first edge of the substrate surface and a first edge of the light-emitting surface of the wavelength conversion structure.

15. The pcLED according to claim 14, wherein a second protrusion distance is created between a second edge of the substrate surface and a second edge of the light-emitting surface of the wavelength conversion structure, and the second protrusion distance is not equal to the first protrusion distance.

16. The pcLED according to claim 11, wherein the transparent structure includes a sidewall connecting the first substrate surface and the second substrate surface and an angle θ between the sidewall and the height, wherein the angle θ is greater than 10° and less than 75°.

17. The pcLED according to claim 16, wherein the angle θ is approximately 45°.

18. The pcLED according to claim 11, wherein the transparent material is glass.

19. The pcLED according to claim 11, wherein the height of the transparent structure is less than 200 μm.

20. A motor vehicle including a light-emitting device, the light-emitting device including the pcLED according to claim 1.

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