Liquid crystal display technology continues to advance, from the most frequently heard LCD, LED, OLED, to the industry's most popular display technology Micro LED, Mini LED, Micro OLED, have you ever wanted to understand, but you still see it in a fog water?
In this regard, we will briefly introduce the characteristics of these new generation display technologies, as well as the differences with the old technologies, so that readers can quickly understand.
LCD
LCD is a "liquid-crystal display". At present, most of the market uses "Thin Film Transistor Liquid Crystal Display" (TFT-LCD) technology. A layer of liquid crystal is sandwiched between two glass substrates. The upper glass substrate is a color filter. The light sheet and the lower glass are inlaid with transistors. When the electric current passes through the transistors, the electric field changes, which causes the original rotation arrangement of the liquid crystal molecules to be twisted, which in turn changes the rotation amplitude of the light passing through, and irradiates the color filter in different proportions. , And then produce different colors.
At present, LCD technology is quite mature, used in general computer and TV screens, and at low cost, it has become the basic technology of consumer products.
LED
LED is called "light-emitting diode". It uses electrical energy to convert into light energy. A voltage is applied to the two terminals of the positive and negative electrodes in the semiconductor. When the current passes, the electrons and holes are combined, and the remaining energy is The form of visible light is released. According to the different materials used, the photon energy will produce light of different wavelengths. Direct-display LEDs are often used in outdoor TV walls or traffic lights, while LED chips are currently the mainstream products for TVs, screen backlights and lighting.
OLED
The driving concept of LED and OLED is quite similar, but the materials used are completely different. OLED is called "Organic Light-Emitting Diode" (Organic Light-Emitting Diode). The basic structure is to make a light-emitting layer of organic material on indium tin oxide (ITO) glass, and then cover the light-emitting layer with a layer of low work function. Metal electrode. Driven by an external voltage, the positive electrode holes and the cathode electrons will combine in the light-emitting layer to generate energy and emit light. The three primary colors of R, G, and B are generated due to different material characteristics to form the basic colors.
The biggest difference between OLED and LCD is self-emission. LCD requires LED backplane and filter, while OLED can self-emission.
Although OLED presents a bright picture, low power consumption, and bendable, organic materials will oxidize, so the lifespan is relatively short, and the problem of color burn will occur. In addition, the cost is high and the technology content is high. At present, most of them are suitable for small screens, such as mobile phones. Screen.
After understanding the basic differences between LCD, LED and OLED, let's look at the high-end display technologies Mini LED, Micro LED and Micro OLED.
Mini LED
The most intuitive difference between Mini LED and Micro LED is the particle size of the LED crystal, but there is a little difference from a conceptual point of view. The official name of Mini LED is "sub-millimeter light emitting diode". Micro LED refers to "micro light emitting diode". The crystal size of the two is basically 100 microns as the boundary, which is about 0.1 mm.
Mini LED is regarded as a transitional period of Micro LED. It is an improved version on the basis of traditional LED backlight. It is used as the backlight source of LCD panels; Micro LED is a new generation of display technology, miniaturizing and matrixing LED backlight sources. Committed to independently driving inorganic self-luminescence (self-luminescence), making products longer life, and even better than OLED, which is regarded by the industry as the next-generation display technology.
At present, Mini LED technology is mainly used for "multi-zone backlight displays" and "large RGB small-pitch displays." The "multi-zone backlight control" function in Mini LED technology can achieve partition dimming, which is like enhancing the high contrast and high resolution of the picture, achieving HDR effect, and the effect is similar to that of OLED displays. Another technology is to use Mini LED chips to create A large screen with a display pixel pitch lower than 1.0 mm pitch can not only improve the resolution of the LED display screen, but also create a new mainstream display screen specification.
Micro LED
As for Micro LED, it will bring new technological breakthroughs, and its use is not limited to backlights. Because Micro LED's crystal grains are indistinguishable to the naked eye, the crystal grains of the three primary colors of R, G, and B can be directly combined into a pixel point. The concept of "one pixel" eliminates the need for filters and liquid crystal layers. It is precisely because this technical feature is completely different from the light-emitting structure of previous LCD display screens, it will bring a new revolution to the LCD industry.
In addition to being expected to create a new situation for the LCD industry, Micro LED will have a broad range of applications in the future, including AR/VR devices, car screens, and high-resolution wearable products. However, there are many difficulties in Micro LED technology that need to be resolved. From the early stage of the epitaxial technology bottleneck, Mass Transfer yield, packaging and testing issues, to subsequent inspections and maintenance are great challenges, affecting Micro LED Can it be mass-produced.
Micro OLED
Micro OLED is a hot topic this year, because Apple has found TSMC to cooperate in the development of Micro OLED panels. The biggest feature of Micro OLED is that unlike traditional TVs, high-end mobile phones, LCD or OLED, the screen is built on a glass substrate, but directly mounted on a wafer.
Micro OLED uses monocrystalline silicon wafer as the backplane, which has the advantages of making the display lighter, thinner, shorter, less power consumption, self-luminous, and high luminous efficiency. It is especially suitable for display wearable devices such as AR and VR.
It is reported that the Micro OLED under development by Apple is less than 1 inch (2.54cm) in size and will be used in Apple's latest augmented reality (AR) products. However, the Micro OLED plan is currently in the trial production stage, and it will take several years to reach the mass production stage.
At present, Sony, Samsung, and BOE are all developing Micro OLED display technology and plan to mass-produce and use it in future wearable devices and AR devices.
