Microdisplays

Abstract

The present invention discloses various aspects of device architecture, optoelectronic systems and methods of developing color microdisplay. In particular, the usage of walls in pixel subarrays is disclosed to prevent leakage of light wherein one sub-array can be covered by color conversion layers to convert the light from the sub-array to a different color. Further, usage of microLEDs with continuous pixelation and common electrode in different combinations is also disclosed.

Description

MICRODISPLAYSField of the invention

[0001] The present disclosure relates to a method of developing full-color microdisplays where the display has more than one sub-array, and each sub-array has only one color. The image from each sub-array is combined with the optical structure to form a full-color display.Summary

[0002] The present invention relates to a microLED display architecture comprising, a backplane with pixel circuits controlling brightness of pixels, the pixels arranged into at least more than one sub-array, wherein sub-arrays are populated with microLEDs, and a color conversion layer covering at least one sub-array.

[0003] The present invention also relates to a method to prevent light from leaking into different sub-arrays in an optoelectronic system, the method comprising, having a backplane and different sub-arrays of microLEDs, wherein the backplane includes pixel circuits controlling the microLEDs, bonding a driver system to the backplane to control the sub-arrays, having at least one sub-array covered by color conversion layers which convert the light from the sub-array to a different color and having an area between the sub-arrays separated by a barrier to prevent light from leaking into different sub-arrays.Brief description of the Drawings

[0004] The foregoing and other advantages of the disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.

[0005] Figure 1(a) shows a microLED sub-arrays for color MicroDisplay for blue sub-arrays.

[0006] Figure 1(b) shows micro LED sub-arrays for color converted sub-arrays.

[0007] Figure 2(a) shows isolated microdevices for the color conversion placement 3D-view.

[0008] Figure 2(b) shows isolated microdevices for the color conversion placement top-view.

[0009] Figure 3 shows isolated continuous microdevices for color conversion placement.

[0010] Figure 4(a)shows a structure with a substrate, microLEDs and walls going over the microLED in 3D view.

[0011] Figure 4(b)shows a structure with a substrate, microLEDs and walls going over the microLED in top view.

[0012] The foregoing description of one or more embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.Detailed Description

[0013] The following description of the invention shows various aspects of device architecture, optoelectronic system and methods of developing color MicroDisplay's.

[0014] The present invention relates to a method of developing full-color MicroDisplay' where the display has more than one sub-array, and each sub-array has only one color. The image from each sub-array is combined with the optical structure to form a full-color display.

[0015] A spacer can be used in the space between two arrays to reduce the light leakage between two arrays. This can allow us to move the arrays closer to each other. The spacer can be a polymer, metal, or dielectric.

[0016] In one related embodiment, at least one of the arrays is converted to different colors using color conversion material. The color conversion covers the array. In another case, another subarray can be converted to a different color by another color conversion layer.

[0017] In one related embodiment, the surface of the array is covered by a grid of walls encircling the emission area of each pixel. The walls can be polymer, metal, dielectric or other materials. The color conversion is then applied to the surface filling the space created by the color conversion materials.

[0018] The color conversion layer can be covered by other materials such as polymer or dielectric. A lens array can be formed on top of the color conversion layer.

[0019] The wall grid can be conductive, acting as the common electrode for the array. In another case, the surface of the array is covered by a dielectric; the metal grid is formed on top of the dielectric. The dielectric layer can have an opening for the electrode to couple to the emitting device or the common electrode.

[0020] Figure 1 shows an optoelectronic system comprising of a backplane 102 and different subarrays 104, 106 and 108 of optoelectronic devices (microLEDs). The backplane includes pixel circuits controlling the optoelectronic devices 104, 106 and 108. A driver system can be bonded to the backplane to control the arrays. At least one sub-array can be covered by color conversionmaterials 112 and 114, which convert the light from the sub-array to a different color. The colorconversion materials can be quantum dots, phosphors, or other nanoparticles. The area between the sub-arrays can be separated by barrier 122 to prevent light from leaking into different subarrays. The color conversion layer can be patterned per pixel in the sub-array. The patterning can be done through photolithography, wet etching, drying, etc. Also, the color conversion layer can be applied to the sub-array using stamping. In another embodiment, a molding structure can pattern the light conversion layer.

[0021] Figure 2(a) shows an embodiment consisting of a backplane 202, a color conversion layer 208 on top of the pixels 204 in the sub-array.

[0022] In the related embodiment, the sub-array around pixel 204 is covered by walls 206, creating housing for the color conversion layer.

[0023] Figure 2(b) shows the top view of the microLED array with walls 206 that the color conversion layer will fully cover.

[0024] Figure 3 shows another related embodiment consisting of a backplane 302 microLEDs 308, walls 304, color conversion layer 306 and a possible common electrode 310. The common electrode can be a blanket layer or patterned to traces — the housing structure coupled with the common electrode to improve the conductivity.

[0025] In another related embodiment, the common electrode is part of the microdevice array and is thinned between each pixel to facilitate light extraction. A dielectric exists between the backplane and the other layers on top of the backplane and the housing walls in another related embodiment. In some areas, openings in the dielectric layer allow the housing wall to couple to the common electrode or bias level.

[0026] In another related embodiment, the wall passes through the middle of microdevices. Figure 4 shows the related structure. Figure 4(a) shows a structure with a substrate 402, microLEDs 408, color conversion layer 404 and walls 406 going over the microLED. Here, the microLED can be covered by a dielectric layer and has an opening where the wall crosses over — the wall couples to the microLEDs. The wall here also acts as part of the common electrode structure.

[0027] Figure 4(b) shows the structure with a substrate, microLEDs and walls going over the microLED in a top view.

[0028] In one related embodiment to structures explained here. The microLEDs are continuous pixelation where at least one of the p-contact layers (p-pad, p-ohmic, p-doped layers or blocking layers) is pixelated. Here, after the array is bonded to the backplane, the n-side of the device faces up. The n-layer can also act as the common electrode. To further improve the pixelation, the n- layer can be made thin so the current from the pixelated p-structure is not spread to a larger area than the pixel. The n-layer is thinned only around the intended pixel in another related embodiment. In one related embodiment, the walls are coupled to the intended area for the pixel by an opening in the dielectric. As a result, the current only passes vertically between the pixelated p-layer(s) and the common electrode. The color conversion layer fills the areas between the walls and maybe over the walls.

[0029] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments or implementations have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of an invention as defined by the appended claims.

Claims

Claims1. A microLED display architecture comprising: a backplane with pixel circuits controlling brightness of pixels; the pixels arranged into at least more than one sub-array, wherein sub-arrays are populated with microLEDs; and a color conversion layer covering at least one sub-array.

2. The display architecture of claim 1, wherein first walls are formed between the sub-arrays to prevent a light leakage.

3. The display architecture of claim 1 wherein secondary walls are formed between the pixels in the sub-array.

4. The display architecture of claim 3, where the secondary walls are conductive and coupled to the common electrode.

5. The display architecture of claim 4, where there is a dielectric between layers on top of a backplane and the secondary walls and the dielectric layer has at least one opening connecting to the common electrode or a bias.

6. The display architecture of claim 5, wherein the microLEDs are continuous structures comprising of pixelated p-layers and common layers to n-layers.

7. The display architecture of claim 6, wherein a conductivity of the n-layer is reduced.

8. The display architecture of claim 7, where the opening in the dielectric layer is on a top of an expected pixel coupling the secondary wall to the n-layer in that area.

9. A method to prevent light from leaking into different sub-arrays in an optoelectronic system, the method comprising: having a backplane and different sub-arrays of microLEDs, wherein the backplane includes pixel circuits controlling the microLEDs; bonding a driver system to the backplane to control the sub-arrays; having at least one sub-array covered by color conversion layers which convert the light from the sub-array to a different color; and having an area between the sub-arrays separated by a barrier to prevent light from leaking into different sub-arrays.

10. The method of claim 9, wherein the color-conversion layer materials are quantum dots, phosphors, or nanoparticles composed material.

11. The method of claim 9, wherein the color-conversion layers are patterned per pixel in the subarray.

12. The method of claim 11, wherein the patterning is done through photolithography, wet etching, or drying.

13. The method of claim 9, the color conversion layer is applied to the sub-array using stamping.

14. The method of claim 9, wherein the color-conversion layers are patterned using a molding structure.

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