Patent Application
20240395849
The micro light-emitting diode (micro LED) is a novel display technology formed by miniature light-emitting chips. In comparison to the LED or organic LED (OLED) display technology according to the prior art, micro LEDs own higher brightness, contrast, and color expressiveness as well as greater performance and longer lifetime.
Compared with the display technologies according to the prior art, micro LEDs own many advantages including primarily the brightness and contrast. The brightness of a micro LED can reach ten times the brightness of a general OLED. The contrast of a micro LED is also higher. These advantages make micro LED displays are apparently superior in color reproduction and image quality.
The advantage of micro LEDs is their color expressiveness. Since micro LED displays adopt pure light sources, they can display a broader color gamut and hence providing truer and more vivid colors. In addition, micro LED displays also provide local brightness adjustment. This means that they can adjust brightness in different regions of a display independently and thus achieving superior contrast and performance.
The third advantage is greater performance and longer lifetime. In addition, micro LEDs use pure light sources. Thereby, no backlight and color filter layer is required, which enhances the light-emitting efficiency.
Owing to the advantages of micro LEDs, they have become the primary choice for high-end display products, including smartphones, tablet computers, televisions, VR/AR helmets, and automotive displays.
As consumers requests for higher quality and resolution, the micro LED technology has attracted more attention. Compared to LCD displays, LED displays, and OLED displays, micro LED displays have higher brightness and better contrast. Besides, they also have a broader color gamut. Consequently, micro LED displays have been regarded as an important development direction for next-generation display technologies.
Furthermore, the advantages of micro LEDs also include reliability and long-term costs. Thanks to their long lifetime and durability, compared to other technologies, micro LEDs are more economical. In addition, due to their low power consumption and long lifetime, this technology can maintain high-quality displays for a long time without excessive maintenance or replacement of parts.
Unfortunately, owing to its miniature size, massive micro LEDs are required to be disposed on the display panel according to the prior art. Because of imperfect process yield, some LEDs cannot operate normally and thus resulting in defective pixels on a micro LED panel. Accordingly, the industry requires a micro LED panel structure capable of repairing abnormal pixels.
To solve the above problem according to the prior art, the present invention provides a micro LED panel structure, which comprises two or more regions on the substrate. The first region includes a plurality of light-emitting layers stacked vertically. When one of the plurality of vertically stacked light-emitting layers is damaged, an alternate light-emitting layer is disposed in the second region.
An objective of the present invention is to provide a micro LED panel structure, in which two or more regions are disposed on the substrate. The first region includes a plurality of light-emitting layers stacked vertically. When one of the plurality of vertically stacked light-emitting layers is damaged, an alternate light-emitting layer is disposed in the second region.
To achieve the above objective and efficacy, the present invention provides a micro LED panel structure, which comprises a substrate, a first light-emitting layer, a second light-emitting layer, and a third light-emitting layer. The substrate includes a first region and a second region thereon. The first region is disposed on one side of the second region. The first light-emitting layer is disposed in the first region. And connected electrically to the substrate via a first fan-out circuit layer from the bottom. The second light-emitting layer is disposed on the first light-emitting layer and connected electrically to the first light-emitting layer via a second fan-out circuit layer from the bottom. The second fan-out circuit layer is connected electrically to the substrate. The third light-emitting layer is disposed on the second light-emitting layer and connected electrically to the second light-emitting layer via a third fan-out circuit layer from the bottom. The third fan-out circuit layer is connected electrically to the substrate. The wavelengths of the light emitted from the first, the second, and the third light-emitting layers are different. When one or more of the first, the second, and the third light-emitting layers is damaged, one or more first alternate light-emitting layer is disposed in the second region. The one or more first alternate light-emitting layer is connected electrically to the substrate via a fourth fan-out circuit layer from the bottom. By using the structure, the micro LED panel structure can be repaired correspondingly.
According to an embodiment of the present invention, the material of the substrate is selected from the group consisting of gallium nitride, gallium arsenide, gallium phosphide, indium phosphide, silicon carbide, and aluminum oxide.
According to an embodiment of the present invention, the micro LED panel structure further comprises a quantum dot layer disposed on the one or more first alternate light-emitting layer.
According to an embodiment of the present invention, the micro LED panel structure further comprises one or more second alternate light-emitting layer disposed on the third light-emitting layer.
According to an embodiment of the present invention, the one or more second alternate light-emitting layer is connected electrically to the third light-emitting layer via a fifth fan-out circuit layer from the bottom.
According to an embodiment of the present invention, the wavelength of the light emitted from the one or more second alternate light-emitting layer is different from the wavelength of the light emitted from the third light-emitting layer.
According to an embodiment of the present invention, the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer include an n-type semiconductor, a p-type semiconductor, and a light-emitting layer, respectively.
According to an embodiment of the present invention, the energy bandgap of the first light-emitting layer is greater than the energy bandgap of the second light-emitting layer; the energy bandgap of the second light-emitting layer is greater than the energy bandgap of the third light-emitting layer.
According to an embodiment of the present invention, the energy bandgap of the first light-emitting layer is smaller than the energy bandgap of the second light-emitting layer; the energy bandgap of the second light-emitting layer is smaller than the energy bandgap of the third light-emitting layer.
According to an embodiment of the present invention, a first area of the first light-emitting layer is greater than a second area of the second light-emitting layer. The second area is greater than a third area of the third light-emitting layer.
In order to make the structure and characteristics as well as the effectiveness of the present invention to be further understood and recognized, the detailed description of the present invention is provided as follows along with embodiments and accompanying figures.
To solve the above problem according to the prior art, the present invention provides a micro LED panel structure, in which two or more regions are disposed on the substrate. A first region includes a plurality of light-emitting layers stacked vertically and connected electrically to one another. When one or more of the plurality of light-emitting layers is damaged, an alternate light-emitting layer is disposed in a second region for repairing the micro LED panel and hence solving the problem of defective pixels owing to abnormal or damaged LEDs on the panel according to the prior art.
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According to the present embodiment, the wavelength of the light emitted from the first light-emitting layer 20 is different from the wavelength of the light emitted from the second light-emitting layer 30; the wavelength of the light emitted from the second light-emitting layer 30 is different from the wavelength of the light emitted from the third light-emitting layer 40; and the wavelength of the light emitted from the first light-emitting layer 20 is different from the wavelength of the light emitted from the third light-emitting layer 40. For example, the first light-emitting layer 20, the second light-emitting layer 30 and the third light-emitting layer 40 emit light with different colors.
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According to the present embodiment, the one or more first alternate light-emitting layer 50 is connected electrically to the substrate 10 via a fourth fan-out circuit layer 52 from the bottom.
According to the present embodiment, the first fan-out circuit layer 22 of the first light-emitting layer 20, the second fan-out circuit layer 32 of the second light-emitting layer 30, the third fan-out circuit layer 42 of the third light-emitting layer 40, and the fourth fan-out circuit layer 52 of the one or more first alternate light-emitting layer 50 are formed by fan-out packaging. The significant feature of fan-out packaging is to make the redistribution layer broader and enable more pin count. Thereby, more functions can be integrated in a single chip and achieving substrate packaging, thinness, and low costs.
According to an embodiment, an air layer or an isolation layer can be disposed between the electrodes of the first fan-out circuit layer 22. Likewise, an air layer or an isolation layer can be disposed between the electrodes of the second fan-out circuit layer 32, the third fan-out circuit layer 42, and the fourth fan-out circuit layer 52. Nonetheless, the present invention is not limited to the embodiment.
According to the present embodiment, the first light-emitting layer 20, the second light-emitting layer 30, and the third light-emitting layer 40 are pervious to light correspondingly so that the light emitted from the first light-emitting layer 20, the second light-emitting layer 30, and the third light-emitting layer 40 can pass through.
According to an embodiment, the one or more first alternate light-emitting layer 50 can be, but not limited to, LEDs emitting blue ore ultraviolet light.
According to an embodiment, the material of the substrate 10 is selected from the group consisting of gallium nitride, gallium arsenide, gallium phosphide, indium phosphide, silicon carbide, and aluminum oxide. Nonetheless, the present invention is not limited to the embodiment.
According to an embodiment, the energy bandgap of the first light-emitting layer 20 is greater than the energy bandgap of the second light-emitting layer 30; the energy bandgap of the second light-emitting layer 30 is greater than the energy bandgap of the third light-emitting layer 40. Nonetheless, the present invention is not limited to the embodiment.
According to an embodiment, the energy bandgap of the first light-emitting layer 20 is smaller than the energy bandgap of the second light-emitting layer 30; the energy bandgap of the second light-emitting layer 30 is smaller than the energy bandgap of the third light-emitting layer 40. Nonetheless, the present invention is not limited to the embodiment.
According to an embodiment, the first light-emitting layer 20, the second light-emitting layer 30, and the third light-emitting layer 40 emit one of the red, green, and blue light. Nonetheless, the present invention is not limited to the embodiment.
According to an embodiment, the material of the first light-emitting layer 20, the second light-emitting layer 30, and the third light-emitting layer 40 are selected from the group consisting of gallium nitride, aluminum indium gallium phosphide, aluminum gallium arsenide, and aluminum gallium phosphide. Nonetheless, the present invention is not limited to the embodiment.
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According to the present embodiment, the quantum dot in the quantum dot layer QD is a semiconductor nanostructure formed by confining excitons in three directions. The confinement can be formed by the electrostatic potential, the interface between two different semiconductor materials, the surface of the semiconductor, or the combination of the above. A quantum dot owns quantized energy spectrum. The corresponding wave function is located in the quantum dot in space but extended to several lattices. A quantum dot only has few integer multiples of electrons, holes, or electron-hole pairs with an integer multiple of fundamental charge.
According to the present embodiment, the fabrication method of quantum dots can be roughly classified into three types: growth by chemical solution, epitaxial growth (or namely extended growth), and confinement by an electric field.
The growth by chemical solution method is to synthesize cadmium sulfide colloid in aqueous solution. By changing the size of the cadmium sulfide colloid, the exciton energy will change accordingly and producing colloidal quantum dots. In an organic solution, uniform quantum dots will be synthesized. The growth by chemical solution method is to dissolve three chalcogens (sulfur, selenium, tellurium) in trioctylphosphine oxide. Next, it reacts with dimethyl cadmium in the organic solution at 200 to 300 Celsius degrees to produce quantum dot materials (cadmium sulfide, cadmium selenide, cadmium telluride) correspondingly. On this basis, many methods to synthesize colloidal quantum dots are developed in the industry. Currently, most semiconductor materials can be adopted to synthesize the corresponding quantum dots by using the growth by chemical solution method.
The epitaxial growth method refers to grow new crystals on a substrate material. If the crystal is tiny enough, quantum dots will be formed. According to different growth mechanisms, the method can be further classified into chemical vapor deposition and molecular beam epitaxy. The quantum dots by the epitaxial growth method is grown on another semiconductor and can be integrated with the traditional semiconductor devices with ease. In addition, since there is no organic ligand, the charge transfer efficiency of epitaxial quantum dots is higher than colloidal quantum dots with easily adjustable energy levels and fewer surface defects. Nonetheless, since both chemical vapor deposition and molecular beam epitaxy require high vacuum or ultra high vacuum, compared to colloidal quantum dots, epitaxial quantum dots are more expensive.
The confinement by electric field method is to distort the energy levels in semiconductor by controlling metal electrodes and forming confinement on carriers. Since the size of quantum dots is nanometer scale, the metal electrode must be fabricated by e-beam lithography making it most costly and lowest in yield. Nonetheless, the energy levels, the number of carriers, and spins of the quantum dots fabricated using this method can controlled easily by modulating the voltage.
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According to the present embodiment, the first light-emitting layer 20, the second light-emitting layer 30, and third light-emitting layer 40 are LEDs. The semiconductor material will be doped by impurities to form the p-n structure. Like other diodes, the current of an LED can flow from the p region (the anode) to the n region (the cathode) easily but not in the reverse direction. Two different carriers, holes and electrons, flow from the electrodes to the p-n structure under different voltages. When holes and electrons meet, they will recombine. Then the electrons will fall to lower energy levels and release energy by photons (the light). The first light-emitting layer 20, the second light-emitting layer 30, and third light-emitting layer 40 can be applied to micro LEDs, which are, but not limited to, micrometer-scale LEDs.
According to an embodiment, the one or more first alternate light-emitting layer 50 includes an n-type semiconductor, a p-type semiconductor, and a light-emitting layer (not shown in the figure) for forming an LED.
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According to the present embodiment, the one or more second alternate light-emitting layer 60 is connected electrically to the third light-emitting layer 40 via a fifth fan-out circuit layer 62 from the bottom.
According to an embodiment, the wavelength of the light emitted from the one or more second alternate light-emitting layer 60 is different from the wavelength of the light emitted from the third light-emitting layer 40. Thereby, the one or more second alternate light-emitting layer 60 and the third light-emitting layer 40 emit light with different colors (including ultraviolet and infrared).
According to an embodiment, the one or more second alternate light-emitting layer 60 includes an n-type semiconductor, a p-type semiconductor, and a light-emitting layer (not shown in the figure) for forming an LED.
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To sum up, the present invention provides a micro LED panel structure, in which two or more regions are disposed on the substrate. A first region includes a plurality of light-emitting layers stacked vertically and connected electrically to one another via fan-out packaging. A second region is reserved in advance. When one or more of the plurality of light-emitting layers is damaged, one or more alternate light-emitting layer is disposed in the second region of the substrate for replacing the abnormal light-emitting layer and repairing the micro LED panel. Hence, the problem of defective pixels owing to abnormal or damaged LEDs on the panel according to the prior art can be solved.
Accordingly, the present invention conforms to the legal requirements owing to its novelty, nonobviousness, and utility. However, the foregoing description is only embodiments of the present invention, not used to limit the scope and range of the present invention. Those equivalent changes or modifications made according to the shape, structure, feature, or spirit described in the claims of the present invention are included in the appended claims of the present invention.
