Display technology has been continuously advancing, from the most commonly heard LCD, LED, OLED, to the most popular display technologies in the industry today: Micro LED, Mini LED, and Micro OLED. Have you ever thought about understanding them but found it confusing?In this article, we will briefly introduce the features of these new generation display technologies and how they differ from older technologies, allowing readers to quickly grasp the concepts.
LCD
LCD stands for “Liquid Crystal Display.” Currently, the market predominantly uses “Thin Film Transistor Liquid Crystal Display” (TFT-LCD) technology, which consists of two glass substrates sandwiching a layer of liquid crystal. The upper glass substrate is a color filter, while the lower glass is embedded with transistors. When an electric current passes through the transistors, the electric field generated causes the liquid crystal molecules to twist, altering the degree of light passing through and projecting different colors onto the color filter.
▲ TFT-LCD technology is most commonly used in LCD panels.
Currently, LCD technology is quite mature and is used in general computer and television screens, with low costs, making it a foundational technology for consumer products.
▲ The imaging principle of a typical LCD monitor.
After understanding LCD, let’s move on to LED and OLED.LEDLED stands for “Light Emitting Diode,” which converts electrical energy into light energy. By applying voltage across the positive and negative terminals within a semiconductor, electrons combine with holes, releasing the remaining energy in the form of visible light. Depending on the materials used, the photon energy will produce different wavelengths of light. Direct view LEDs are often used in outdoor TV walls or traffic lights, while LED chips are currently the mainstream products for television and screen backlighting and lighting.
▲ LED technology converts electrical energy into light energy.
OLEDLED and OLED have very similar driving concepts, but the materials used are completely different. OLED stands for “Organic Light Emitting Diode,” and its basic structure involves creating an organic material light-emitting layer on indium tin oxide (ITO) glass, covered by a low work function metal electrode. Under external voltage, positive holes from the anode and electrons from the cathode combine in the light-emitting layer, generating energy and emitting light, producing the primary colors R, G, and B to form basic colors due to the different properties of the materials.▲ OLED technology.The biggest difference between OLED and LCD is self-emission; LCD requires an LED backlight and filter, while OLED can emit light by itself.Although OLED presents vibrant images, has low power consumption, and can be bent, organic materials oxidize, leading to a relatively short lifespan and color burn-in issues. Additionally, due to high costs and technical complexity, it is mostly suitable for small screens, such as smartphone displays.After understanding the basic differences between LCD, LED, and OLED, let’s look at the advanced display technologies: Mini LED, Micro LED, and Micro OLED.Mini LEDThe most intuitive difference between Mini LED and Micro LED is the size of the LED crystals, but conceptually there are slight differences. Mini LED is formally known as “Sub-Millimeter Light Emitting Diode,” while Micro LED refers to “Micro Light Emitting Diode.” The crystal size of the two is generally divided by 100 microns, about 0.1 millimeters.
▲ Micro LED technology no longer requires a filter and liquid crystal layer.
Mini LED is seen as a transitional phase to Micro LED, an improved version based on traditional LED backlighting, used as a backlight for LCD panels. Micro LED, on the other hand, is a new generation display technology that miniaturizes and matrices the LED backlight, aiming for individual driving of inorganic self-emitting (self-emission), extending product lifespan and potentially outperforming OLED, being regarded as the next generation display technology by the industry.Currently, Mini LED technology is mainly used in “Multi-Zone Backlight Displays” and “Large RGB Small Pitch Displays.” The “Multi-Zone Backlight Control” feature in Mini LED technology achieves local dimming, enhancing high contrast and high resolution for HDR effects, comparable to OLED displays; another technology uses Mini LED chips to create large screens with pixel spacing less than Pitch 1.0 mm, improving the resolution of LED displays and creating new mainstream specifications for display screens.Micro LEDAs for Micro LED, it brings new technological breakthroughs; its applications are not limited to backlighting. Since the Micro LED crystals reach a level that is indistinguishable to the naked eye, they can directly combine the R, G, and B primary color crystals into one pixel point, transforming the concept of “one pixel” without the need for filters and liquid crystal layers. This technological characteristic is completely different from the light-emitting structure of traditional LCD displays, which will revolutionize the LCD industry.
▲ Mass transfer of crystals onto the circuit matrix is extremely challenging.
In addition to potentially creating a new landscape for the LCD industry, the future applications of Micro LED are extensive, including AR/VR devices, automotive displays, and high-resolution wearable products. However, the Micro LED technology faces many challenges that need to be resolved, from the initial crystal growth technology bottlenecks, mass transfer yields, packaging testing issues, to subsequent detection and maintenance, which are significant challenges affecting the mass production of Micro LED.
Micro OLED
Micro OLED has become a hot topic this year as Apple has partnered with TSMC to develop Micro OLED panels. The biggest feature of Micro OLED is that unlike traditional televisions or high-end mobile phones that build screens on glass substrates, it is directly mounted on wafers.Micro OLED uses single crystal silicon wafers as the backing, offering advantages such as making displays lighter, thinner, lower power consumption, self-emission, and high luminous efficiency, particularly suitable for AR, VR, and other wearable display devices.It is reported that Apple’s developing Micro OLED has a size of less than 1 inch (2.54 cm), which will be used in Apple’s latest augmented reality (AR) products. However, the Micro OLED project is currently in the trial production stage and will take several more years to reach mass production.Currently, Sony, Samsung, and BOE are all developing Micro OLED display technology, planning to mass produce and use it in future wearable devices and AR devices.Source: Technology News
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Source: Technology News
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