Micro light-emitting display device

This application claims the priority benefit of Taiwanese application serial no. 110126889, filed on Jul. 22, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

This disclosure relates to a micro light-emitting display device.

The current mass transfer technology for display devices formed by micro light-emitting diode (micro LED) cannot be made over a large area at a time on the display region, but is made by multiple transfers over a small area to splice the display devices. However, the multiple transfers also causes the display device to be prone to splicing lines after lighting up. The phenomenon may come from chip shift or brightness difference between different display regions and cause shift between groups, which may easily produce splicing lines.

The disclosure provides a micro light-emitting display device capable of reducing a phenomenon of splicing lines.

An embodiment of the disclosure provides a micro light-emitting display device having multiple display regions. The micro light-emitting display device includes a substrate, multiple micro light-emitting elements, and multiple first light-emitting auxiliary structures. The micro light-emitting elements are disposed on the substrate, and positions of the micro light-emitting elements define ranges of the display regions. The micro light-emitting elements have a same first pitch between each other in any one of the display regions. The micro light-emitting elements have a second pitch between each other at a boundary across any two adjacent display regions. The first pitch is different from the second pitch. The first light-emitting auxiliary structures are respectively disposed on the micro light-emitting elements. The first light-emitting auxiliary structures have a same third pitch between each other.

An embodiment of the disclosure provides a micro light-emitting display device having multiple display regions. The micro light-emitting display device includes a substrate, multiple micro light-emitting elements, and multiple light-emitting auxiliary structures. The micro light-emitting elements are disposed on the substrate, and positions of the micro light-emitting elements define ranges of the display regions, the micro light-emitting elements have a same first pitch between each other in any one of the display regions, and the micro light-emitting elements have a second pitch between each other at a boundary across any two adjacent display regions. The first pitch is different from the second pitch. The light-emitting auxiliary structures are respectively disposed on the micro light-emitting elements. The light-emitting auxiliary structures are reflective layers or absorbing layers, and each of the light-emitting auxiliary structures has an opening. Areas of the openings of the light-emitting auxiliary structures gradually increase or decrease at the boundary across the any two adjacent display regions.

Based on the above, in the micro light-emitting display device according to an embodiment of the disclosure, since the light-emitting auxiliary structures have the same pitch between each other, effective area of light-emitting is redefined, and therefore the phenomenon of splicing lines between the display regions is mitigated.

To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows.

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

FIG. 1 A is a schematic top view of a micro light-emitting display device according to a first embodiment of the disclosure.

FIG. 1 B is a schematic side view of the micro light-emitting display device of FIG. 1 A .

FIG. 2 is a schematic side view of a micro light-emitting display device according to a second embodiment of the disclosure.

FIG. 3 A is a schematic top view of a micro light-emitting display device according to a third embodiment of the disclosure.

FIG. 3 B is a schematic side view of the micro light-emitting display device according to the third embodiment of the disclosure.

FIG. 4 A is a schematic top view of a micro light-emitting display device according to a fourth embodiment of the disclosure.

FIG. 4 B is a schematic side view of the micro light-emitting display device of FIG. 4 A .

FIG. 5 is a schematic side view of a micro light-emitting display device according to a fifth embodiment of the disclosure.

FIG. 6 is a schematic side view of a micro light-emitting display device according to a sixth embodiment of the disclosure.

FIG. 7 A is a schematic top view of a micro light-emitting display device according to a seventh embodiment of the disclosure.

FIG. 7 B is a schematic side view of the micro light-emitting display device of FIG. 7 A .

FIG. 8 A is a schematic top view of a micro light-emitting display device according to an eighth embodiment of the disclosure.

FIG. 8 B is a schematic side view of the micro light-emitting display device of FIG. 8 A .

FIG. 9 is a schematic side view of a micro light-emitting display device according to a ninth embodiment of the disclosure.

FIG. 1 A is a schematic top view of a micro light-emitting display device according to a first embodiment of the disclosure. FIG. 1 B is a schematic side view of the micro light-emitting display device of FIG. 1 A . For the convenience of illustration, the drawings in the specification simply show two display regions R 1 and R 2 , but the number of the display regions R 1 and R 2 that a micro light-emitting display device 10 may have should be determined by actual production conditions. Moreover, the number of a micro light-emitting element 200 in each of the display regions R 1 and R 2 is simply shown as 3 ×3. For example, an area of the each of the display regions R 1 and R 2 falls in the range of approximately 20×20 to 30×30 mm 2 . Therefore, an order of magnitude of the number of the micro light-emitting element 200 in the display regions R 1 and R 2 is greater than 10 3 .

Referring FIG. 1 A and FIG. 1 B at the same time. An embodiment of the disclosure provides a micro light-emitting display device 10 having multiple display regions R 1 and R 2 . The micro light-emitting display device 10 includes a substrate 100 , multiple micro light-emitting elements 200 , and multiple first light-emitting auxiliary structures 300 . The substrate 100 is, for example, a thin-film transistor (TFT) substrate, a printed circuit board (PCB), a flexible printed circuit (FPC) board, or other types of circuit substrates. The micro light-emitting element 200 may be micro light-emitting diode (Micro LED), mini light-emitting diode (Mini LED) or other types of micro light-emitting elements. The micro light-emitting element 200 is electrically connected to the substrate 100 by a connection between a bonding pad 202 of the micro light-emitting element 200 and a bonding pad 102 of the substrate 100 .

According to this embodiment, the micro light-emitting elements 200 are disposed on the substrate 100 , and positions of the micro light-emitting elements 200 define ranges of the display regions R 1 and R 2 . In detail, the micro light-emitting elements 200 have a same first pitch P 1 between each other in any one of the display regions R 1 and R 2 . However, the micro light-emitting elements 200 have a second pitch P 2 between each other at a boundary across any two adjacent display regions R 1 and R 2 . The first pitch P 1 is different from the second pitch P 2 . Therefore, a distribution of the micro light-emitting elements 200 visually has a phenomenon of splicing lines at a junction between the display regions R 1 and R 2 .

In order to solve the phenomenon of splicing lines, according to this embodiment, the first light-emitting auxiliary structures 300 are respectively disposed on the micro light-emitting elements 200 . The first light-emitting auxiliary structures 300 have a same third pitch P 3 between each other. The first light-emitting auxiliary structure 300 is configured so that the first pitch P 1 is the same as the third pitch P 3 . That is, as shown in the top view of FIG. 1 A , the first light-emitting auxiliary structures 300 have the same pitch between each other, thus reducing the phenomenon of splicing lines at the junction between the display regions R 1 and R 2 .

According to this embodiment, the third pitch P 3 is less than or equal to 1 μm. According to one embodiment, the third pitch P 3 is less than or equal to 500 μm for a better display.

According to this embodiment, the first light-emitting auxiliary structures 300 may be light-guide structures, and refractive index of the first light-emitting auxiliary structures 300 is greater than 1 and less than refractive index of the micro light-emitting elements 200 . This refractive index difference helps to improve light-emitting efficiency of each of the micro light-emitting elements 200 . The light-guide structures may be inorganic materials, such as silicon dioxide or silicon nitride, in addition to increasing a light-guide effect, may also withstand high temperature and pressure in a process to protect a surface of the micro light-emitting elements 200 . The first light-emitting auxiliary structures 300 account for at least 0.5 of a surface 204 of the micro light-emitting elements, which may have better light-guide efficiency.

In addition, according to this embodiment, in the any two adjacent display regions R 1 and R 2 , minimum distances d 1 and d 2 between edges of the first light-emitting auxiliary structures 300 and edges of the micro light-emitting elements 200 are different from each other, and a light-emitting light pattern may be controlled.

Based on the above, in the micro light-emitting display device 10 according to an embodiment of the disclosure, since the micro light-emitting elements 200 are provided with the light-emitting auxiliary structures 300 thereon, and the light-emitting auxiliary structures 300 have the same pitch between each other, effective area of light emission is redefined, and therefore the phenomenon of splicing lines between the display regions R 1 and R 2 is mitigated.

FIG. 2 is a schematic side view of a micro light-emitting display device according to a second embodiment of the disclosure. Referring to FIG. 2 , a micro light-emitting display device 10 A is substantially the same as the micro light-emitting display device 10 of FIG. 1 B , and main differences are as follows. According to this embodiment, first light-emitting auxiliary structures 300 A- 1 , 300 A- 2 , and 300 A- 3 have multiple different areas. FIG. 2 shows that the area of the light-emitting auxiliary structure 300 A- 1 is larger than the area of the light-emitting auxiliary structure 300 A- 2 , 300 A- 3 , and the area of the light-emitting auxiliary structure 300 A- 2 is equal to the area of the light-emitting auxiliary structure 300 A- 3 . For example, the light-emitting auxiliary structures 300 A- 1 , 300 A- 2 , and 300 A- 3 are respectively disposed on red, green, and blue micro light-emitting elements 200 . Generally speaking, light-emitting efficiency of red light-emitting diodes is lower than light-emitting efficiency of green light-emitting diodes and blue light-emitting diodes. Therefore, the first light-emitting auxiliary structures 300 A- 1 , 300 A- 2 , and 300 A- 3 are designed to have multiple different areas. For example, the light-emitting auxiliary structure 300 A- 1 corresponding to the red light-emitting device 200 is larger than the first light-emitting auxiliary structures 300 A- 2 and 300 A- 3 corresponding to the green light-emitting device 200 and the blue light-emitting device 200 , which helps to make brightness of each color light of the micro light-emitting display device 10 A more consistent.

FIG. 3 A is a schematic top view of a micro light-emitting display device according to a third embodiment of the disclosure. FIG. 3 B is a schematic side view of the micro light-emitting display device according to the third embodiment of the disclosure. Referring to FIG. 3 A and FIG. 3 B , a micro light-emitting display device 10 B is substantially the same as the micro light-emitting display device 10 of FIG. 1 B , and main differences are as follows. According to this embodiment, micro light-emitting elements 200 B- 1 , 200 B- 2 , and 200 B- 3 have multiple different light-emitting areas, but each corresponding light-emitting auxiliary structures 300 has the same area. FIG. 3 B shows that a size of the micro light-emitting element 200 B- 1 is larger than a size of the micro light-emitting element 200 B- 2 , 200 B- 3 , and the size of the micro light-emitting element 200 B- 2 is equal to the size of the micro light-emitting element 200 B- 3 . For example, the micro light-emitting elements 200 B- 1 , 200 B- 2 , and 200 B- 3 may be red, green, and blue light-emitting diodes, respectively, or light-emitting diodes of the same light color. The sizes of the micro light-emitting elements are different due to manufacturing process, and the sizes of the micro light-emitting elements reflect area sizes of light-emitting layers 206 - 1 , 206 - 2 and 206 - 3 . Therefore, the light-emitting auxiliary structures 300 on the micro light-emitting elements 200 B- 1 , 200 B- 2 , 200 B- 3 with different light-emitting areas are designed to have the same area, which helps to make brightness of each color light of the micro light-emitting display device 10 B more consistent, and it is possible to increase an utilization rate of chips by eliminating the need to binning the light-emitting elements first.

FIG. 4 A is a schematic top view of a micro light-emitting display device according to a fourth embodiment of the disclosure. FIG. 4 B is a schematic side view of the micro light-emitting display device of FIG. 4 A . Referring FIG. 4 A and FIG. 4 B at the same time, a micro light-emitting display device 10 C is substantially the same as the micro light-emitting display device 10 of FIG. 1 B , and main differences are as follows. According to this embodiment, first light-emitting auxiliary structures 300 C are reflective layers or absorbing layers, and each of first light-emitting auxiliary structures 300 C has an opening O. The openings O of the first light-emitting auxiliary structures 300 C have a same third pitch P 3 between each other. The first light-emitting auxiliary structures 300 C may be organic materials with high absorptivity, such as a black photoresist, or a metal material with high reflectivity. The openings O account for at least greater than or equal to 0.5 of a surface 204 of the micro light-emitting elements 200 , which may have better light-guide efficiency.

According to this embodiment, more specifically, projection of the micro light-emitting elements 200 on the substrate 100 completely covers projection of the openings O of the first light-emitting auxiliary structures 300 C on the substrate 100 , i.e., the opening O is smaller than a light-emitting surface of the micro light emitting element 200 , and the light-emitting light pattern may be controlled.

In addition, according to this embodiment, in the any two adjacent display regions R 1 and R 2 , minimum thicknesses t 1 and t 2 between edges of the first light-emitting auxiliary structures 300 and the openings O thereof are different from each other, and design of the openings O may be controlled.

Based on the above, in the micro light-emitting display device 10 C according to the embodiment of the disclosure, the first light-emitting auxiliary structures 300 C are designed as reflective layers or absorbing layers, and positions of the openings O are adjusted so that a light-emitting position of the each of the micro light-emitting elements 200 are consistent. Therefore, by adjusting display areas, the phenomenon of splicing lines between the adjacent display regions R 1 and R 2 of the micro light-emitting display device 10 C is mitigated.

FIG. 5 is a schematic side view of a micro light-emitting display device according to a fifth embodiment of the disclosure. Referring to FIG. 5 , a micro light-emitting display device 10 D is substantially the same as the micro light-emitting display device 10 C of FIG. 4 B , and main differences are as follows. According to this embodiment, the micro light-emitting display device 10 D further includes multiple second light-emitting auxiliary structures 400 . The second light-emitting auxiliary structures 400 are respectively disposed in the openings O of the first light-emitting auxiliary structures 300 C. The second light-emitting auxiliary structures 400 have a same fourth pitch P 4 between each other, and the fourth pitch P 4 is the same as the third pitch P 3 .

According to this embodiment, the second light-emitting auxiliary structures 400 are light-guide structures, and refractive index of the second light-emitting auxiliary structures 400 is greater than 1 and less than the refractive index of the micro light-emitting elements 200 .

According to this embodiment, projection of the second light-emitting auxiliary structure 400 on the substrate 100 and the projection of the micro light-emitting element 200 on the substrate 100 overlap with each other. More specifically, the projection of the micro light-emitting element 200 on the substrate 100 completely covers the projection of the second light-emitting auxiliary structure 400 on the substrate 100 , i.e., the second light-emitting auxiliary structure 400 is smaller than the light-emitting surface of the micro light-emitting element 200 .

Based on the above, in the micro light-emitting display device 10 D according to the embodiment of the disclosure, in addition to adjusting the positions of the openings O of the first light-emitting auxiliary structures 300 C to make the light-emitting position of the each of the micro light-emitting elements 200 consistent, the second light-emitting auxiliary structures 400 are further disposed in the openings O. Therefore, the micro light-emitting display device 10 D may not only reduce brightness to mitigate the phenomenon of splicing lines between the adjacent display regions R 1 and R 2 , but also use the second light-emitting auxiliary structures 400 to improve the light-emitting efficiency of the micro light-emitting display device 10 D.

FIG. 6 is a schematic side view of a micro light-emitting display device according to a sixth embodiment of the disclosure. Referring FIG. 6 , a micro light-emitting display device 10 E is substantially the same as the micro light-emitting display device 10 D of FIG. 5 , and main differences are as follows. According to this embodiment, a portion of second light-emitting auxiliary structures 400 E is extended and disposed on surfaces of the first light-emitting auxiliary structures 300 C opposite to the micro light-emitting elements 200 . Here, projection of the second light-emitting auxiliary structures 400 E on the surface of the micro light-emitting elements 200 is greater than projection of the openings O on the surface of the micro light-emitting elements 200 , and the projections of the second light-emitting auxiliary structures 400 E on the surface of the micro light-emitting elements 200 are the same, so as to increase the light-emitting efficiency and consistent display effect. Advantages of the micro light-emitting display device 10 E are similar to advantages of the micro light-emitting display device 10 D, and therefore will not be repeated in the following

FIG. 7 A is a schematic top view of a micro light-emitting display device according to a seventh embodiment of the disclosure. FIG. 7 B is a schematic side view of the micro light-emitting display device of FIG. 7 A . Referring to FIG. 7 A and FIG. 7 B at the same time, a micro light-emitting display device 10 F is substantially the same as the micro light-emitting display device 10 C of FIG. 4 B , and main differences are as follows. According to this embodiment, first light-emitting auxiliary structures 300 F are connected to each other, and the first light-emitting auxiliary structures 300 F are disposed in space between the micro light-emitting elements 200 . Here, the first light-emitting auxiliary structures 300 F fill the space between the micro light-emitting elements 200 , so that splicing lines between the display regions R 1 and R 2 are covered, further reducing the phenomenon of splicing lines in the micro light-emitting display device 10 F and increasing a contrast ratio by a high black ratio. According to an embodiment not shown, the first light-emitting auxiliary structures 300 F may also fill only space between the display region R 1 and R 2 .

FIG. 8 A is a schematic top view of a micro light-emitting display device according to an eighth embodiment of the disclosure. FIG. 8 B is a schematic side view of the micro light-emitting display device of FIG. 8 A . Referring FIG. 8 A and FIG. 8 B at the same time, a micro light-emitting display device 10 G is substantially the same as the micro light-emitting display device 10 C of FIG. 4 B , and main differences are as follows. According to this embodiment, the micro light-emitting display device 10 G further includes a light-transmitting layer 500 . The light-transmitting layer 500 is disposed between first light-emitting auxiliary structures 300 G and the micro light-emitting elements 200 , and the light-transmitting layer 500 is disposed in the space between the micro light-emitting elements 200 . In other words, the light-transmitting layer 500 may be used as a protective layer of the micro light-emitting elements 200 , which helps prevent water in the air from contaminating the micro light-emitting elements 200 , further making the micro light-emitting display device 10 G have a better yield. The light-transmitting layer 500 may be a plastic material with refractive index greater than 1 and less than the refractive index of the micro light-emitting elements 200 , which allows the micro light-emitting elements 200 to have a better light-emitting effect. Here, the light-emitting auxiliary structures 300 G may be reflective layers or absorbing layers, so that light is emitted through the openings O.

FIG. 9 is a schematic side view of a micro light-emitting display device according to a ninth embodiment of the disclosure. Referring FIG. 9 , a micro light-emitting display device 10 H is substantially the same as the micro light-emitting display device 10 C of FIG. 4 B , and main differences are as follows. According to this embodiment, light-emitting auxiliary structures 300 H are reflective layers or absorbing layers, and each of the light-emitting auxiliary structures 300 H has openings O 1 , O 2 , and O 3 . Areas of the openings O 1 , O 2 , and O 3 of the light-emitting auxiliary structures 300 H gradually increase or decrease at the boundary across the any two adjacent display regions R 1 and R 2 , and same openings O 1 , O 2 or O 3 has a same opening size.

In addition, if an area ratio between the openings O 1 , O 2 , and O 3 is too large or too small, it will lead to a more obvious phenomenon of splicing lines. Therefore, according to this embodiment, the area ratio between the openings O 1 , O 2 and O 3 of the light-emitting auxiliary structures 300 H preferably falls within a range of 0.8 to 1.2.

Based on the above, by designing the areas of the openings O 1 , O 2 , and O 3 near the splicing line to gradually increase or decrease, it also helps to reduce a visual phenomenon of splicing lines at the junction between the display regions R 1 and R 2 . Preferably, only 10% of the light-emitting auxiliary structures 300 H at the boundary has an increase or gradual decrease of the openings, and the openings in a middle display region still maintain the same opening size, which may have a better display effect.

In summary, in the micro light-emitting display device according to an embodiment of the disclosure, since the light-emitting auxiliary structures have the same pitch between each other, effective area of light-emitting is redefined, and therefore the phenomenon of splicing lines between the display regions is mitigated.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.