LCD display is a very mature display technology. OLED screens are emerging and used in many mobile phones and TVs. Micro LED is a new generation of display technology that will provide better visual effects.
LCD
Liquid Crystal Display, the liquid crystal display. The LED display refers to a type of liquid crystal display (LCD), that is, a liquid crystal display with LED (light emitting diode) as the backlight source. Here is an explanation of the working principle of TFT LCD.
[Advantage]
- Low cost and long life: LCD display technology is relatively mature. Compared with OLED, LCD has lower manufacturing difficulty and cost, and has a longer lifespan
- No stroboscopic: The backlight of the LCD is an independent white LED backlight panel, so basically no flicker can be achieved;
- High Pixel Density: With the same resolution, the display effect of LCD is clearer than that of OLED.
- High power consumption: LCD products are thicker and consume more power than OLEDs because LCDs require additional backlights;
- Low Contrast: LCD cannot turn off the backlight when displaying black, but blocks the light by liquid crystal molecules, so it will appear a gray-white color.
OLED
Organic Light-Emitting Diode (OLED) refers to the phenomenon in which organic semiconductor materials and light-emitting materials are driven by an electric field and lead to light emission through carrier injection and recombination.
Under the action of the electric field, the holes generated by the anode and the electrons generated by the cathode will move, injected into the hole transport layer and the electron transport layer, respectively, and migrate to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated, thereby exciting the light-emitting molecules and finally producing visible light.
[Advantage]
- Each pixel of the OLED screen is self-illuminating, so it is thinner and lighter than LCD;
- Low power consumption and flexibility: Compared with LCD, OLED saves the structure of backlight, liquid crystal and color filter, lower power consumption, and can realize flexible display;
- High contrast ratio, high brightness, high luminous efficiency, and more vivid image colors: OLED is self-luminous, so it can be completely non-luminous when necessary, and the display black is more pure;
- The unit response speed of OLED screen is faster than that of LCD screen.
- OLED screen burn-in hidden danger;
- The lifespan of blue OLEDs is relatively short;
- The stroboscopic phenomenon is obvious, the color is bright and there is a color cast problem, which will cause harm to the eyes when used for a long time;
- Low pixel density, the same resolution, the display effect is not as good as the LCD display effect.
Micro LED
Micro LED (also known as μLed) refers to a chip with a size less than 100μm. Like ordinary LEDs, it is also self-illuminating. LED chips with three RGB luminous colors are used to form pixels one by one for display.
[Advantage]
- Compared with LCD and OLED, Micro LED display has fast response speed, high brightness, large viewing angle, good color effect and long life
- It has the characteristics of self-illumination without backlight, small size, light and thin, and can also achieve the effect of energy saving.
[Difficulties in production technology]
- Mass transfer technology: How to miniaturize LEDs requires wafer-level technology.
- Chip technology: For Micro LEDs that retain the substrate, the biggest challenge is cutting. As chip size gets smaller, the split yield also decreases.
- Driving IC technology: When Micro LED is in use, its power driving current is very low compared to small spacing. Under low current, the low gray-scale state of traditional IC is not good, which will cause Micro LED to have the same current but brightness The difference is large or even some parts are not bright.
- Inspection and maintenance: Because the size of Micro LED is too small, its electrode size is often smaller than that of the probe needle, so it cannot be inspected by conventional spot inspection technology.
