US20200083281A1 - Top emission microled display and bottom emission microled display and a method of forming the same - Google Patents

Abstract

A microLED display includes a first main substrate, microLEDs disposed above the first main substrate, a first light blocking layer disposed above the first main substrate to define emission areas, a light guiding layer disposed in the emission areas, and a plurality of connecting structures disposed in the emission areas respectively and electrically connected with the microLEDs.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation application of U.S. application Ser. No. 16/128,255, filed on Sep. 11, 2018, the entire contents of which are herein expressly incorporated by reference.
BACKGROUND OF THEINVENTION1. Field of the Invention
• The present invention generally relates to a light-emitting diode (LED) display, and more particularly to a top emission microLED display and a bottom emission microLED display.
2. Description of Related Art
• A micro light-emitting diode (microLED, mLED or μLED) display panel is one type of flat display panel, which is composed of microscopic microLEDs each having a size of 1-10 micrometers.
• Compared to conventional liquid crystal display panels, the microLED display panels offer better contrast, response time and energy efficiency. Although both organic light-emitting diodes (OLEDs) and microLEDs possess good energy efficiency, the microLEDs, based on group III/V (e.g., GaN) LED technology, offer higher brightness, higher luminous efficacy and longer lifespan than the OLEDs.
• Active matrix using thin-film transistors (TFT) may be used in companion with microLEDs to drive a display panel. However, microLED is made by flip chip technology, while TFT is made by complementary metal-oxide-semiconductor (CMOS) process which is more complex than flip chip technology. These two distinct technologies may cause thermal mismatch. A drive current of the microLED is small in gray display, which may be significantly affected by leakage current.
• Passive matrix is another driving method performed by a row drive circuit and a column drive circuit, which are disposed on the periphery of a display panel. When the size or the resolution of the display panel increases, output loading and delay of the drive circuits increase accordingly, causing the display panel to malfunction. Therefore, passive matrix is not suitable for large-size microLED display panels.
• A need has thus arisen to propose a novel microLED display panel, particularly a large-size or high-resolution display panel, which is capable of maintaining advantages of microLEDs and overcoming disadvantages of driving schemes.
• As adjacent microLEDs are near to each other, interference (e.g., color mixing) between adjacent microLEDs may happen and thus decrease contrast ratio. Moreover, non-uniform display may happen due to connecting wires composed of opaque or reflective material that connecting the microLEDs with other components or circuits.
• A need has thus arisen to propose a novel microLED display with luminous efficacy improvement over the conventional microLED displays.
SUMMARY OF THE INVENTION
• In view of the foregoing, it is an object of the embodiment of the present invention to provide structures and forming methods of a top emission microLED display and a bottom emission microLED display capable of prevent interference, color mixing and non-uniform display issues.
• According to one embodiment, a top emission microLED display includes a first main substrate; a bottom common electrode layer disposed on a top surface of the first main substrate; a plurality of microLEDs disposed on the bottom common electrode layer; a first light blocking layer disposed on the bottom common electrode layer to define a plurality of emission areas; a light guiding layer disposed in the emission areas; and a plurality of connecting structures disposed in the emission areas respectively and electrically connected with the microLEDs.
• According to another embodiment, a bottom emission microLED display includes a first main substrate; a plurality of microLEDs disposed above the first main substrate; a first light blocking layer disposed above the first main substrate to define a plurality of emission areas; a light guiding layer disposed in the emission areas; a plurality of connecting structures disposed in the emission areas respectively and electrically connected with the microLEDs; and a top common electrode layer disposed above the first light blocking layer and the microLEDs.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 schematically shows a side view of a top emission microLED display;
• FIG. 2A shows a top view of a top emission microLED display according to a first embodiment of the present invention;
• FIG. 2B shows a cross-sectional view ofFIG. 2A;
• FIG. 2C shows a cross-sectional view of a top emission microLED display according to a modified first embodiment of the present invention;
• FIG. 2D shows another top view of the top emission microLED display according to the first embodiment of the present invention;
• FIG. 3A shows a top view of a top emission microLED display according to a second embodiment of the present invention;
• FIG. 3B shows a cross-sectional view ofFIG. 3A;
• FIG. 3C shows a cross-sectional view of a top emission microLED display according to a modified second embodiment of the present invention;
• FIG. 3D shows another top view of the top emission microLED display according to the second embodiment of the present invention;
• FIG. 4A shows a top view of a top emission microLED display according to a third embodiment of the present invention;
• FIG. 4B shows a cross-sectional view ofFIG. 4A;
• FIG. 4C shows a cross-sectional view of a top emission microLED display according to a modified third embodiment of the present invention;
• FIG. 5A shows a top view of a top emission microLED display according to a fourth embodiment of the present invention;
• FIG. 5B shows a cross-sectional view ofFIG. 5A;
• FIG. 5C shows a cross-sectional view of a top emission microLED display according to a modified fourth embodiment of the present invention;
• FIG. 6 shows a cross-sectional view of a top emission microLED display according to a fifth embodiment of the present invention;
• FIG. 7A toFIG. 13B show top views and cross-sectional views illustrating steps of forming a top emission microLED display according to one embodiment of the present invention;
• FIG. 14 schematically shows a side view of a bottom emission micro light-emitting diode (microLED) display;
• FIG. 15A shows a top view of a bottom emission microLED display according to a sixth embodiment of the present invention;
• FIG. 15B shows a cross-sectional view ofFIG. 15A;
• FIG. 15C shows a cross-sectional view of a bottom emission microLED display according to a modified sixth embodiment of the present invention;
• FIG. 15D shows another top view of the bottom emission microLED display according to the sixth embodiment of the present invention;
• FIG. 16A shows a top view of a bottom emission microLED display according to a seventh embodiment of the present invention;
• FIG. 16B shows a cross-sectional view ofFIG. 16A;
• FIG. 16C shows a cross-sectional view of a bottom emission microLED display according to a modified seventh embodiment of the present invention;
• FIG. 16D shows another top view of the bottom emission microLED display according to the seventh embodiment of the present invention;
• FIG. 17A shows a top view of a bottom emission microLED display according to an eighth embodiment of the present invention;
• FIG. 17B shows a cross-sectional view ofFIG. 17A;
• FIG. 17C shows a cross-sectional view of a bottom emission microLED display according to a modified eighth embodiment of the present invention;
• FIG. 18A shows a top view of a bottom emission microLED display according to a ninth embodiment of the present invention;
• FIG. 18B shows a cross-sectional view ofFIG. 18A;
• FIG. 18C shows a cross-sectional view of a bottom emission microLED display according to a modified ninth embodiment of the present invention;
• FIG. 19 shows a cross-sectional view of a bottom emission microLED display according to a tenth embodiment of the present invention;
• FIG. 20A toFIG. 26B show top views and cross-sectional views illustrating steps of forming a bottom emission microLED display according to one embodiment of the present invention;
• FIG. 27 shows a cross-sectional view of a bottom emission microLED display according to an eleventh embodiment of the present invention;
• FIG. 28 shows a cross-sectional view of a top emission microLED display according to a twelfth embodiment of the present invention;
• FIG. 29 shows a cross-sectional view of a bottom emission microLED display according to a thirteenth embodiment of the present invention;
• FIG. 30 shows a cross-sectional view of a bottom emission microLED display according to a modified thirteenth embodiment of the present invention;
• FIG. 31 shows a cross-sectional view of a bottom emission microLED display according to a fourteenth embodiment of the present invention; and
• FIG. 32 shows a cross-sectional view of a bottom emission microLED display according to a modified fourteenth embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
• FIG. 1 schematically shows a side view of a top emission micro light-emitting diode (microLED)display100. In the embodiment, microLEDs12 (e.g.,red microLED12R,green microLED12G andblue microLED12B) may be disposed on a top surface of amain substrate11 by a bonding technique. As themicroLEDs12 emit light upward (as shown by arrows) against the top surface of themain substrate11, thedisplay100 is called a top emission microLED display. In the specification, themicroLEDs12 have a size of 1-10 micrometers, which may be decreased or increased according to specific applications or technological development in the future.
• FIG. 2A shows a top view of a topemission microLED display200 according to a first embodiment of the present invention, andFIG. 2B shows a cross-sectional view ofFIG. 2A. In the embodiment, microLEDs22 (e.g.,red microLED22R,green microLED22G andblue microLED22B) may be disposed above a (first)main substrate21A. A (first)light blocking layer23A is disposed between adjacent microLEDs22 and above the (first)main substrate21A to prevent interference (e.g., color mixing) between adjacent microLEDs22 and to enhance contrast. A bottomcommon electrode layer28 may be disposed between themain substrate21A and themicroLEDs22. In the present embodiment (and the following embodiments), themicroLED22 may be a rectangle, for example, with a length of 25 micrometers and a width of 10 micrometers. According to one aspect of the embodiment, themicroLEDs22 may be disposed longitudinally. That is, the length of themicroLED22 is parallel to the longitude of thedisplay200, and the width of the microLED is parallel to the latitude of thedisplay200. As human eyes are more sensitive to vertically emitted light than horizontally emitted light, thedisplay200 of the embodiment can enhance viewing angle.
• The (first)light blocking layer23A of the embodiment may include black matrix (BM). In the embodiment shown inFIG. 2B, black resin is first formed, followed by adopting photo process and curing process to form the BM (first)light blocking layer23A. In another embodiment, ink-jet printing technique and curing process are adopted to form the BM (first)light blocking layer23A.
• The (first)light blocking layer23A definesemission areas24, which are not covered with the (first)light blocking layer23A. In other words, areas other than theemission areas24 are covered with the (first)light blocking layer23A. Alight guiding layer25, composed of light guiding material, is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. The light guiding material is transparent with high refractive index. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the (first)light blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than or equal to themicroLEDs22.
• FIG. 2C shows a cross-sectional view of a topemission microLED display200 according to a modified first embodiment of the present invention. In the embodiment shown inFIG. 2C, the (first)light blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the (first)light blocking layer23A and thelight guiding layer25 partially overlap each other, and the (first)light blocking layer23A is partially covered with thelight guiding layer25. In the embodiment shown inFIG. 2C, a chromium/chromium oxide film is first formed, followed by adopting photo etching technique to form the BM (first)light blocking layer23A.
• FIG. 2D shows another top view of the topemission microLED display200 according to the first embodiment of the present invention. A connectingstructure26, such as conductive electrode, is disposed on a top surface of themicroLED22 in eachemission area24. The connectingstructure26 may include transparent material (e.g., indium tin oxide), opaque material (e.g., metal) or reflective material. According to one aspect of the embodiment, the connectingstructures26 in theemission areas24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 3A shows a top view of a topemission microLED display300 according to a second embodiment of the present invention, andFIG. 3B shows a cross-sectional view ofFIG. 3A. The second embodiment is similar to the first embodiment with the exception that, in the second embodiment, the (first)light blocking layer23A is disposed between adjacent pixels (instead of adjacent microLEDs22) to prevent interference (e.g., color mixing) between adjacent pixels and to enhance contrast.
• The (first)light blocking layer23A definesemission areas24, which are not covered with the (first)light blocking layer23A. In other words, areas other than theemission areas24 are covered with the (first)light blocking layer23A. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the (first)light blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 3B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22.
• FIG. 3C shows a cross-sectional view of a topemission microLED display300 according to a modified second embodiment of the present invention. In the embodiment shown inFIG. 3C, the (first)light blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the (first)light blocking layer23A and thelight guiding layer25 partially overlap each other, and the (first)light blocking layer23A is partially covered with thelight guiding layer25.
• FIG. 3D shows another top view of the topemission microLED display300 according to the second embodiment of the present invention. A connectingstructure26, such as conductive electrode, is disposed on a top surface of themicroLED22 in eachemission area24. According to one aspect of the embodiment, the connectingstructures26 in theemission areas24 have the same pattern and the connectingstructures26 in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 4A shows a top view of a topemission microLED display400 according to a third embodiment of the present invention, andFIG. 4B shows a cross-sectional view ofFIG. 4A. In the embodiment, microLEDs22 (e.g.,red microLED22R,green microLED22G andblue microLED22B) may be disposed above a (first)main substrate21A. EachmicroLED22 corresponds to anemission area24. In the embodiment, a frame-shaped firstlight blocking layer23A surrounds theemission area24 and is disposed above the (first)main substrate21A. In the embodiment, a blockingsubstrate27 is disposed above the (first)main substrate21A and the firstlight blocking layer23A. A secondlight blocking layer23B, which covers areas other than theemission areas24 and the firstlight blocking layer23A, is disposed on a bottom surface of the blockingsubstrate27. The firstlight blocking layer23A and the secondlight blocking layer23B partially overlap each other. Accordingly, an aperture d1 of the firstlight blocking layer23A is different from (e.g., smaller than) an aperture d2 of the secondlight blocking layer23B. In another embodiment, the aperture of the firstlight blocking layer23A is greater than the aperture of the secondlight blocking layer23B. In the embodiment, the firstlight blocking layer23A and the secondlight blocking layer23B may include BM, and the blockingsubstrate27 may include transparent material such as quartz, glass or plastic material.
• Alight guiding layer25, composed of light guiding material, is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the firstlight blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 4B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22.
• FIG. 4C shows a cross-sectional view of a topemission microLED display400 according to a modified third embodiment of the present invention. In the embodiment shown inFIG. 4C, the firstlight blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the firstlight blocking layer23A is partially covered with thelight guiding layer25.
• According to one aspect of the embodiment, the connecting structures26 (not shown) in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 5A shows a top view of a topemission microLED display500 according to a fourth embodiment of the present invention, andFIG. 5B shows a cross-sectional view ofFIG. 5A. The fourth embodiment is similar to the third embodiment with the exception that, in the fourth embodiment, the firstlight blocking layer23A and the secondlight blocking layer23B are disposed between adjacent pixels (instead of adjacent microLEDs22) to prevent interference (e.g., color mixing) between adjacent pixels and to enhance contrast.
• In the embodiment, each pixel (which includesred microLED22R,green microLED22G andblue microLED22B) corresponds to anemission area24. In the embodiment, a frame-shaped firstlight blocking layer23A surrounds theemission area24 and is disposed above the (first)main substrate21A. In the embodiment, a secondlight blocking layer23B, which covers areas other than theemission areas24 and the firstlight blocking layer23A, is disposed on a bottom surface of the blockingsubstrate27. The firstlight blocking layer23A and the secondlight blocking layer23B partially overlap each other. Accordingly, an aperture d1 of the firstlight blocking layer23A is different from (e.g., smaller than) an aperture d2 of the secondlight blocking layer23B. In the embodiment, the firstlight blocking layer23A and the secondlight blocking layer23B may include BM, and the blockingsubstrate27 may include transparent material such as quartz, glass or plastic material.
• Alight guiding layer25, composed of light guiding material, is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the firstlight blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 5B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22.
• FIG. 5C shows a cross-sectional view of a topemission microLED display500 according to a modified fourth embodiment of the present invention. In the embodiment shown inFIG. 5C, the firstlight blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the firstlight blocking layer23A is partially covered with thelight guiding layer25.
• According to one aspect of the embodiment, the connecting structures26 (not shown) in theemission areas24 have the same pattern and the connectingstructures26 in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 6 shows a cross-sectional view of a topemission microLED display600 according to a fifth embodiment of the present invention. In the embodiment, the topemission microLED display600 may include a firstmain substrate21A and a secondmain substrate21B, which are disposed at a same level but correspond to distinct microLED displays, respectively. A firstlight blocking layer23A is disposed above the firstmain substrate21A and the secondmain substrate21B. Similar to the fourth embodiment, the topemission microLED display600 may include a secondlight blocking layer23B, which covers areas other than theemission areas24 and the firstlight blocking layer23A, being disposed on a bottom surface of the blockingsubstrate27. As shown inFIG. 6, the firstmain substrate21A and the secondmain substrate21B correspond to thesame blocking substrate27, and the firstlight blocking layer23A of the firstmain substrate21A and the secondlight blocking layer23B of the secondmain substrate21B correspond to the same secondlight blocking layer23B at a joint of the firstmain substrate21A and the secondmain substrate21B. Accordingly, multiple microLED displays may be joined to become a seamless topemission microLED display600.
• FIG. 7A toFIG. 13B show top views and cross-sectional views illustrating steps of forming a top emission microLED display according to one embodiment of the present invention. As shown inFIG. 7A andFIG. 7B, a (first)main substrate21A, which defines anemission area24, is provided. As shown inFIG. 8A andFIG. 8B, a bottomcommon electrode layer28 is formed on a top surface of the (first)main substrate21A. According to one aspect of the embodiment, the bottomcommon electrode layer28 entirely covers theemission area24 to prevent nonuniform display issue.
• As shown inFIG. 9A andFIG. 9B, microLEDs12 (e.g.,red microLED12R,green microLED12G andblue microLED12B) are disposed on a top surface of the bottomcommon electrode layer28 by a bonding technique. As shown inFIG. 10A andFIG. 10B, a (first)light blocking layer23A is disposed in an area other than theemission area24 to prevent interference (e.g., color mixing) between adjacent pixels and to enhance contrast.
• As shown inFIG. 11A andFIG. 11B, alight guiding layer25 is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24. Thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 11B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22. It is noted that the order of forming the (first)light blocking layer23A (FIG. 10A andFIG. 10B) and forming the light guiding layer25 (FIG. 11A andFIG. 11B) may be exchanged.
• As shown inFIG. 12A andFIG. 12B, contact holes are formed above themicroLEDs22. Next, as shown inFIG. 13A andFIG. 13B, connectingstructures26 are formed to connect themicroLED22. The connectingstructures26 have the same pattern and the connectingstructures26 in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 14 schematically shows a side view of a bottom emission micro light-emitting diode (microLED)display1400. In the embodiment, microLEDs12 (e.g.,red microLED12R,green microLED12G andblue microLED12B) may be disposed above amain substrate11 by a bonding technique. As themicroLEDs12 emit light downward (as shown by arrows) against the top surface of themain substrate11, thedisplay1400 is called a bottom emission microLED display. In the specification, themicroLEDs12 have a size of 1-10 micrometers, which may be decreased or increased according to specific applications or technological development in the future.
• FIG. 15A shows a top view of a bottomemission microLED display1500 according to a sixth embodiment of the present invention, andFIG. 15B shows a cross-sectional view ofFIG. 15A. In the embodiment, microLEDs22 (e.g.,red microLED22R,green microLED22G andblue microLED22B) may be disposed on a top surface of a (first)main substrate21A. A (first)light blocking layer23A is disposed between adjacent microLEDs22 and above the (first)main substrate21A to prevent interference (e.g., color mixing) between adjacent microLEDs22 and to enhance contrast. A topcommon electrode layer28 may be disposed above themicroLEDs22 and thelight blocking layer23A.
• The (first)light blocking layer23A of the embodiment may include black matrix (BM). In the embodiment shown inFIG. 15B, black resin is first formed, followed by adopting photo process and curing process to form the BM (first)light blocking layer23A. In another embodiment, ink-jet printing technique and curing process are adopted to form the BM (first)light blocking layer23A.
• The (first)light blocking layer23A definesemission areas24, which are not covered with the (first)light blocking layer23A. In other words, areas other than theemission areas24 are covered with the (first)light blocking layer23A. Alight guiding layer25, composed of light guiding material, is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. The light guiding material is transparent with high refractive index. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the (first)light blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 15B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22.
• FIG. 15C shows a cross-sectional view of a bottomemission microLED display1500 according to a modified sixth embodiment of the present invention. In the embodiment shown inFIG. 15C, the (first)light blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the (first)light blocking layer23A and thelight guiding layer25 partially overlap each other, and the (first)light blocking layer23A is partially covered with thelight guiding layer25. In the embodiment shown inFIG. 15C, a chromium/chromium oxide film is first formed, followed by adopting photo etching technique to form the BM (first)light blocking layer23A.
• FIG. 15D shows another top view of the bottomemission microLED display1500 according to the sixth embodiment of the present invention. A connectingstructure26, such as conductive electrode, is disposed between the microLEDs22 and themain substrate21A in eachemission area24. The connectingstructure26 may include transparent material (e.g., indium tin oxide), opaque material (e.g., metal) or reflective material. According to one aspect of the embodiment, the connectingstructures26 in theemission areas24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 16A shows a top view of a bottomemission microLED display1600 according to a seventh embodiment of the present invention, andFIG. 16B shows a cross-sectional view ofFIG. 16A. The seventh embodiment is similar to the sixth embodiment with the exception that, in the seventh embodiment, the (first)light blocking layer23A is disposed between adjacent pixels (instead of adjacent microLEDs22) to prevent interference (e.g., color mixing) between adjacent pixels and to enhance contrast.
• The (first)light blocking layer23A definesemission areas24, which are not covered with the (first)light blocking layer23A. In other words, areas other than theemission areas24 are covered with the (first)light blocking layer23A. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the (first)light blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 16B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22.
• FIG. 16C shows a cross-sectional view of a bottomemission microLED display1600 according to a modified seventh embodiment of the present invention. In the embodiment shown inFIG. 16C, the (first)light blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the (first)light blocking layer23A and thelight guiding layer25 partially overlap each other, and the (first)light blocking layer23A is partially covered with thelight guiding layer25.
• FIG. 16D shows another top view of the bottomemission microLED display1600 according to the seventh embodiment of the present invention. A connectingstructure26, such as conductive electrode, is disposed on a top surface of themicroLED22 in eachemission area24. According to one aspect of the embodiment, the connectingstructures26 in theemission areas24 have the same pattern and the connectingstructures26 in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 17A shows a top view of a bottomemission microLED display1700 according to an eighth embodiment of the present invention, andFIG. 17B shows a cross-sectional view ofFIG. 17A. In the embodiment, microLEDs22 (e.g.,red microLED22R,green microLED22G andblue microLED22B) may be disposed above a (first)main substrate21A. EachmicroLED22 corresponds to anemission area24. In the embodiment, a frame-shaped firstlight blocking layer23A surrounds theemission area24 and is disposed above the (first)main substrate21A. In the embodiment, a blockingsubstrate27 is disposed below the (first)main substrate21A. A secondlight blocking layer23B, which covers areas other than theemission areas24 and the firstlight blocking layer23A, is disposed on a top surface of the blockingsubstrate27. The firstlight blocking layer23A and the secondlight blocking layer23B partially overlap each other. Accordingly, an aperture d1 of the firstlight blocking layer23A is different from (e.g., smaller than) an aperture d2 of the secondlight blocking layer23B. In another embodiment, the aperture of the firstlight blocking layer23A is greater than the aperture of the secondlight blocking layer23B. In the embodiment, the firstlight blocking layer23A and the secondlight blocking layer23B may include BM, and the blockingsubstrate27 may include transparent material such as quartz, glass or plastic material.
• Alight guiding layer25, composed of light guiding material, is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the firstlight blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 17B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22.
• FIG. 17C shows a cross-sectional view of a bottomemission microLED display1700 according to a modified eighth embodiment of the present invention. In the embodiment shown inFIG. 17C, the firstlight blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the firstlight blocking layer23A is partially covered with thelight guiding layer25.
• According to one aspect of the embodiment, the connecting structures26 (not shown) in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 18A shows a top view of a bottomemission microLED display1800 according to a ninth embodiment of the present invention, andFIG. 18B shows a cross-sectional view ofFIG. 18A. The ninth embodiment is similar to the eighth embodiment with the exception that, in the ninth embodiment, the firstlight blocking layer23A and the secondlight blocking layer23B are disposed between adjacent pixels (instead of adjacent microLEDs22) to prevent interference (e.g., color mixing) between adjacent pixels and to enhance contrast.
• In the embodiment, each pixel (which includesred microLED22R,green microLED22G andblue microLED22B) corresponds to anemission area24. In the embodiment, a frame-shaped firstlight blocking layer23A surrounds theemission area24 and is disposed above the (first)main substrate21A. In the embodiment, a secondlight blocking layer23B, which covers areas other than theemission areas24 and the firstlight blocking layer23A, is disposed on a top surface of the blockingsubstrate27. The firstlight blocking layer23A and the secondlight blocking layer23B partially overlap each other. Accordingly, an aperture d1 of the firstlight blocking layer23A is different from (e.g., smaller than) an aperture d2 of the secondlight blocking layer23B. In the embodiment, the firstlight blocking layer23A and the secondlight blocking layer23B may include BM, and the blockingsubstrate27 may include transparent material such as quartz, glass or plastic material.
• Alight guiding layer25, composed of light guiding material, is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24.
• In the embodiment, the firstlight blocking layer23A has a thickness greater than thelight guiding layer25. Further, thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 18B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22.
• FIG. 18C shows a cross-sectional view of a bottomemission microLED display1800 according to a modified ninth embodiment of the present invention. In the embodiment shown inFIG. 18C, the firstlight blocking layer23A has a thickness less than thelight guiding layer25. Moreover, the firstlight blocking layer23A is partially covered with thelight guiding layer25.
• According to one aspect of the embodiment, the connecting structures26 (not shown) in theemission areas24 have the same pattern and the connectingstructures26 in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• FIG. 19 shows a cross-sectional view of a bottomemission microLED display1900 according to a tenth embodiment of the present invention. In the embodiment, the bottomemission microLED display1900 may include a firstmain substrate21A and a secondmain substrate21B, which are disposed at a same level but correspond to distinct microLED displays, respectively. A firstlight blocking layer23A is disposed above the firstmain substrate21A and the secondmain substrate21B. Similar to the ninth embodiment, the bottomemission microLED display1900 may include a secondlight blocking layer23B, which covers areas other than theemission areas24 and the firstlight blocking layer23A, being disposed on a top surface of the blockingsubstrate27. As shown inFIG. 19, the firstmain substrate21A and the secondmain substrate21B correspond to thesame blocking substrate27, and the firstlight blocking layer23A of the firstmain substrate21A and the secondlight blocking layer23B of the secondmain substrate21B correspond to the same secondlight blocking layer23B at a joint of the firstmain substrate21A and the secondmain substrate21B. Accordingly, multiple microLED displays may be joined to become a seamless bottomemission microLED display1900.
• FIG. 20A toFIG. 26B show top views and cross-sectional views illustrating steps of forming a bottom emission microLED display according to one embodiment of the present invention. As shown inFIG. 20A andFIG. 20B, a (first)main substrate21A, which defines anemission area24, is provided. As shown inFIG. 21A andFIG. 21B, connectingstructures26 are formed to connect themicroLED22. The connectingstructures26 have the same pattern and the connectingstructures26 in eachemission area24 have the same pattern, which can prevent nonuniform display issue.
• As shown inFIG. 22A andFIG. 22B, microLEDs12 (e.g.,red microLED12R,green microLED12G andblue microLED12B) are disposed on a top surface of the bottomcommon electrode layer28 by a bonding technique. As shown inFIG. 23A andFIG. 23B, a (first)light blocking layer23A is disposed in an area other than theemission area24 to prevent interference (e.g., color mixing) between adjacent pixels and to enhance contrast.
• As shown inFIG. 24A andFIG. 24B, alight guiding layer25 is disposed in theemission areas24 to spread the light emitted by themicroLEDs22. In the embodiment, thelight guiding layer25 is entirely formed in theemission areas24. Thelight guiding layer25 has a thickness greater than themicroLEDs22 as shown inFIG. 24B. In another embodiment, however, thelight guiding layer25 has a thickness less than or equal to themicroLEDs22. It is noted that the order of forming the (first)light blocking layer23A (FIG. 23A andFIG. 23B) and forming the light guiding layer25 (FIG. 24A andFIG. 24B) may be exchanged.
• As shown inFIG. 25A andFIG. 25B, contact holes are formed above themicroLEDs22. Next, as shown inFIG. 26A andFIG. 26B, a topcommon electrode layer28 is formed above thelight guiding layer25. According to one aspect of the embodiment, the topcommon electrode layer28 entirely covers theemission area24 to prevent nonuniform display issue.
• FIG. 27 shows a cross-sectional view of a bottomemission microLED display2000 according to an eleventh embodiment of the present invention. Compared toFIG. 19, the bottomemission microLED display2000 of the present embodiment may include at least oneshielding layer30 for blocking electromagnetic interference (EMI). In one embodiment, theshielding layer30 may include transparent conductive material such as transparent conductive oxide (e.g., indium tin oxide (ITO), indium zinc oxide (IZO) or aluminum doped Zinc Oxide (AZO)).
• Theshielding layer30 may be disposed between a top surface of the firstmain substrate21A and firstlight blocking layer23A. Theshielding layer30 may be electrically insulated from the topcommon electrode layer28 by an insulating layer29, and may be electrically insulated from the connectingstructure26 by an insulatinglayer31. Similarly, theshielding layer30 may be disposed between a top surface of the secondmain substrate21B and firstlight blocking layer23A. Theshielding layer30 may be electrically insulated from the topcommon electrode layer28 by an insulating layer29, and may be electrically insulated from the connectingstructure26 by an insulatinglayer31. Theshielding layer30 may be disposed between a top surface of the blockingsubstrate27 and the secondlight blocking layer23B. Generally speaking, theshielding layer30 may be disposed in one or more areas mentioned above.
• Theshielding layer30 may be adaptable to a top emission microLED display.FIG. 28 shows a cross-sectional view of a topemission microLED display2100 according to a twelfth embodiment of the present invention. Compared toFIG. 6, the topemission microLED display2100 of the present embodiment may include at least oneshielding layer30 for blocking electromagnetic interference (EMI). In one embodiment, theshielding layer30 may include transparent conductive material such as transparent conductive oxide (e.g., indium tin oxide (ITO), indium zinc oxide (IZO) or aluminum doped Zinc Oxide (AZO)). In the embodiment, theshielding layer30 may be disposed between a bottom surface of the blockingsubstrate27 and the secondlight blocking layer23B.
• FIG. 29 shows a cross-sectional view of a bottomemission microLED display2900 according to a thirteenth embodiment of the present invention. Compared toFIG. 15B, the bottomemission microLED display2900 of the present embodiment may include ananti-floodlight layer32 disposed on a bottom surface of the firstmain substrate21A and betweenadjacent microLEDs22. In other words, theanti-floodlight layer32 may be disposed on the firstmain substrate21A opposite the (first)light blocking layer23A.FIG. 30 shows a cross-sectional view of a bottomemission microLED display2900 according to a modified thirteenth embodiment of the present invention. Compared toFIG. 15C, the bottomemission microLED display2900 of the present embodiment may include ananti-floodlight layer32 disposed on a bottom surface of the firstmain substrate21A and betweenadjacent microLEDs22. In other words, theanti-floodlight layer32 may be disposed on the firstmain substrate21A opposite the (first)light blocking layer23A.
• After the light emitted by themicroLEDs22 enters the firstmain substrate21A, some of the generated light passes through the firstmain substrate21A, while other of the generated light laterally diffuses in the firstmain substrate21A due to total reflection, which may interfere withadjacent microLED22 or pixel to result in floodlight issue. Theanti-floodlight layer32 of the embodiment may absorb lateral diffused light and effectively avoid floodlight issue.
• Theanti-floodlight layer32 of the embodiment may include BM. In one example, a chromium/chromium oxide film is first formed, followed by adopting photo etching technique to form theBM anti-floodlight layer32. In another example, black resin is first formed, followed by adopting photo process and curing process to form theBM anti-floodlight layer32. In a further example, ink-jet printing technique and curing process are adopted to form theBM anti-floodlight layer32. Theanti-floodlight layer32 may be directly formed on the firstmain substrate21A, or may be first formed on another substrate, which is then attached on the firstmain substrate21A.
• As discussed above, theanti-floodlight layer32 may be disposed betweenadjacent microLEDs22. However, theanti-floodlight layer32 may be disposed between adjacent pixels.FIG. 31 shows a cross-sectional view of a bottomemission microLED display3100 according to a fourteenth embodiment of the present invention. Compared to the seventh embodiment shown inFIG. 16B, the bottomemission microLED display3100 of the present embodiment may include ananti-floodlight layer32 disposed on a bottom surface of the firstmain substrate21A and between adjacent pixels. In other words, theanti-floodlight layer32 may be disposed on the firstmain substrate21A opposite the (first)light blocking layer23A.FIG. 32 shows a cross-sectional view of a bottomemission microLED display3100 according to a modified fourteenth embodiment of the present invention. Compared to the modified seventh embodiment shown inFIG. 16C, the bottomemission microLED display3100 of the present embodiment may include ananti-floodlight layer32 disposed on a bottom surface of the firstmain substrate21A and between adjacent pixels. In other words, theanti-floodlight layer32 may be disposed on the firstmain substrate21A opposite the (first)light blocking layer23A.
• Although specific embodiments have been illustrated and described, it will be appreciated by those skilled in the art that various modifications may be made without departing from the scope of the present invention, which is intended to be limited solely by the appended claims.

Claims (22)

What is claimed is:

1. A method of forming a top emission microLED display, comprising:

providing a first main substrate;

forming a plurality of microLEDs above the first main substrate;

forming a first light blocking layer above the first main substrate to define a plurality of emission areas;

forming a light guiding layer in the emission areas; and

forming a plurality of connecting structures disposed in the emission areas respectively and electrically connected with the microLEDs.

2. The method ofclaim 1, wherein the connecting structures have a same pattern.

3. The method ofclaim 1, wherein the connecting structures comprise transparent material.

4. The method ofclaim 1, wherein the connecting structures comprise opaque material.

5. The method ofclaim 1, before forming the microLEDs, further comprising a step of entirely forming a conductive layer in the emission areas of the first main substrate.

6. The method ofclaim 1, before forming the connecting structures, further comprising a step of forming contact holes above the microLEDs.

7. The method ofclaim 1, wherein the first light blocking layer comprises black matrix.

8. The method ofclaim 1, wherein a red microLED, a green microLED and a blue microLED in the emission area respectively correspond to the connecting structures with a same pattern.

9. The method ofclaim 1, wherein the step of forming the first light blocking layer comprises:

forming black resin; and

treating the black resin by photo process and curing process to form the first light blocking layer with black matrix.

10. The method ofclaim 1, wherein the step of forming the first light blocking layer comprises:

using ink-jet printing technique and curing process to form the first light blocking layer with black matrix.

11. The method ofclaim 1, wherein the step of forming the first light blocking layer comprises:

forming a chromium/chromium oxide film; and

treating the chromium/chromium oxide film by photo etching technique to form the first light blocking layer with black matrix.

12. A method of forming a bottom emission microLED display, comprising:

providing a first main substrate;

forming a plurality of connecting structures in a plurality of emission areas;

forming a plurality of microLEDs above the connecting structures;

forming a first light blocking layer above the first main substrate to define the emission areas covering the connecting structures; and

forming a light guiding layer in the emission areas.

13. The method ofclaim 12, wherein the connecting structures have a same pattern.

14. The method ofclaim 12, wherein the connecting structures comprise transparent material.

15. The method ofclaim 12, wherein the connecting structures comprise opaque material.

16. The method ofclaim 12, after forming the light guiding layer or the first light blocking layer, further comprising a step of entirely forming a conductive layer in the emission areas of the first main substrate.

17. The method ofclaim 16, before forming the conductive layer, further comprising a step of forming contact holes above the microLEDs.

18. The method ofclaim 12, wherein the first light blocking layer comprises black matrix.

19. The method ofclaim 12, wherein a red microLED, a green microLED and a blue microLED in the emission area respectively correspond to the connecting structures with a same pattern.

20. The method ofclaim 12, wherein the step of forming the first light blocking layer comprises:

forming black resin; and

treating the black resin by photo process and curing process to form the first light blocking layer with black matrix.

21. The method ofclaim 12, wherein the step of forming the first light blocking layer comprises:

using ink-jet printing technique and curing process to form the first light blocking layer with black matrix.

22. The method ofclaim 12, wherein the step of forming the first light blocking layer comprises:

forming a chromium/chromium oxide film; and

treating the chromium/chromium oxide film by photo etching technique to form the first light blocking layer with black matrix.

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