URL:https://www.reshine-display.com/what-is-the-difference-between-led-and-lcd.html

Although there are big differences between LCD and LED displays, there is a lot of confusion in the market, which shouldn’t happen. Part of the confusion comes from the manufacturers. We will clarify as below.

LCD Displays vs LED Displays

The abbreviation for "liquid crystal display" is LCD. LCD cannot produce light on its own; it must rely on a backlight. Previously, manufacturers used CCFL (cold cathode fluorescent lamps) as a backlight, which is bulky and unfriendly to the environment. Then, as LED (light-emitting diode) technology advanced, more and more backlights began to use LEDs. Manufacturers label them as LED monitors or TVs, leading consumers to believe they are purchasing LED displays. However, both LED and LCD televisions are liquid crystal displays. The basic technology is the same in that both types of television have two layers of polarized glass through which liquid crystals block and pass light. LED TVs are thus a subset of LCD TVs. Click here for TFT LCD Display.

Quantum Dot Displays

TVs with quantum dots have also received a lot of attention recently. This particular LCD TV has an LED backlight. While the image is produced exactly like it would be on an LCD screen, the color is improved by quantum dot technology.

When you turn on a typical LCD display, all of the LEDs illuminate, even in areas that shouldn't be lit up (for instance, some areas require black). No matter how flawless the LCD is made, a small amount of light will still pass through it, making it challenging to create a background that is completely black. The contrast gets dimmer.

Full-array backlit quantum dot TV sets with local dimming technology are available and improve image uniformity and deeper blacks. There can be edge-lit quantum-dot sets with no local dimming (thinner, but you may see light banding and grayer blacks).

Photo-emissive quantum dot particles are used in RGB filters, replacing traditional colored photoresists with a QD layer. The quantum dots are excited by the blue light from the display panel to emit pure basic colors, which reduces light losses and color crosstalk in RGB filters, improving display brightness and color gamut. Although this technology is primarily used in LED-backlit LCDs, it applies to other display technologies which use color filters, such as blue/UV AMOLED(Active Matrix Organic Light Emitting Diodes)/QNED(Quantum nano-emitting diode)/Micro LED display panels. LED-backlit LCDs are the main application of quantum dots, where they are used to offer an alternative to very expensive OLED displays.

Micro LEDs and Mini LEDs

Micro LED is a true LED display without hiding at the backside of the LCD as a backlight. It is an emerging flat-panel display technology. Micro LED displays consist of arrays of microscopic LEDs forming individual pixel elements. When compared with widespread LCD technology, micro-LED displays offer better contrast, response times, and energy efficiency.

Micro LEDs can be used in small, low-energy devices such as AR glasses, VR headsets, smartwatches, and smartphones. Micro LED offers greatly reduced energy requirements when compared to conventional LCD systems while having a very high contrast ratio. The inorganic nature of micro-LEDs gives them a long lifetime of more than 100,000 hours.

Micro LED displays have not yet been mass-produced as of 2020, though Luumii and Sony, Samsung, and Konka sell microLED lighting and microLED video walls, respectively. Prototypes have been shown by LG, Tianma, PlayNitride, TCL/CSoT, Jasper Display, Jade Bird Display, Plessey Semiconductors Ltd., and Ostendo Technologies, Inc. MicroLED screens, which can replace current cinema screens, are already available from Sony and Freedeo. Leyard, Epistar, and BOE all have plans for mass producing microLEDs. Like OLEDs, microLEDs can be made transparent and flexible. There is some misunderstanding regarding quantum dot displays and mini-LEDs used as LCD backlights.

According to our understanding, a mini-LED is simply a larger size of a micro LED that can be used for larger size movie theater screens, advertisement walls, luxurious home theaters, etc. The LED size is a key characteristic used to distinguish between Mini-LED and Micro-LED. Inorganic LEDs are the foundation of both Mini-LED and Micro-LED. Mini-LEDs are regarded as LEDs in the millimeter range, while Micro-LEDs are regarded as LEDs in the micrometer range, as their names suggest. The distinction is not as clear-cut in practice, and different people may have different definitions of it. However, it is generally acknowledged that mini-LEDs are much larger than micro-LEDs, which are typically under 100 m and even under 50 m in size.

When applied in the display industry, size is just one factor when people are talking about Mini-LED and Micro-LED displays. Another feature is the LED thickness and substrate. Mini-LEDs usually have a large thickness of over 100 µm, largely due to the existence of LED substrates. While Micro-LEDs are usually substrates and therefore the finished LEDs are extremely thin.

A third feature that is used to distinguish the two is the mass transfer techniques that are utilized to handle the LEDs. Mini-LEDs usually adopt conventional pick-and-place techniques including surface mounting technology. Every time the number of LEDs that can be transferred is limited. For Micro-LEDs, usually, millions of LEDs need to be transferred when a heterogenous target substrate is used, therefore the number of LEDs to be transferred at a time is significantly larger, and thus disruptive mass transfer technique should be considered.

It is exciting to see all the kinds of display technologies which make our world colorful. We believe that LCD and/or LED displays will play very important roles in the future metaverse.