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LED VS LCD: All-round Interpretation

Customers often ask me whether LCD and LED look alike, are they the same thing? As a senior engineer who has been engaged in the research and development of LED displays for a long time, I will analyze  LED VS LCD from simple to in-depth based on the information I know.

First, let’s take a look at the definitions of the two:

LED VS LCD Definition

LED, the full name of light-emitting diode, is a semiconductor light source that looks like a reduced version of an incandescent lamp, but its light-emitting principle is actually different from that of an incandescent lamp.

The full name of LCD is liquid crystal display. It is a flat and thin display device that can place light sources or reflect ambient light sources. To understand it simply, it is more like a mirror.

I don’t know if you have noticed that LED is a light source, while LCD is a display device. The two are obviously different.

Technology Comparison

Materials used

LED is a filament made of various compounds (such as aluminum gallium arsenide, indium gallium nitride, etc.), which can emit light of different colors when energized.

LED Light
LED Light

As for the liquid crystal materials used in LCD, this depends on the high-level subjects we have studied before. All matter with uniform motion in the world belongs to phase state. In addition to the familiar solid state and liquid state, there are also unfamiliar liquid crystal states and plasma states.

Liquid Crystal
Liquid Crystal

LCD uses a liquid crystal state that we are not familiar with. This material has special optical properties and is sensitive to electromagnetic fields, making it very valuable for research.

Comparing the shapes of the two, although they both belong to the phase state, LED uses solid compounds, while LCD uses liquid crystal compounds, and the two are also different.

Luminous principle

LEDs emit light autonomously, and when current passes through them, the materials of these semiconductors move evenly, creating a light source. These semiconductor materials can only emit one color of light at a time. 

In order to display full-color colors, three different compounds need to be combined and energized together to produce full-color colors.

The LCD itself cannot emit light and needs to rely on a backlight to emit light, so the whole process is quite tortuous.

Depending on the liquid crystal material, there are nematic liquid crystals and smectic liquid crystals. The biggest difference between the two is that nematic liquid crystals have lower viscosity and stronger fluidity. Therefore, it is more widely used.

With the characteristics of nematic liquid crystal, only a very small force is needed to change the movement of liquid crystal molecules so that the optical axis of the liquid crystal is consistent with its molecular axis, thereby producing optical effects. 

The Arrangement Of Liquid Crystal Molecules In The Current State
The Arrangement Of Liquid Crystal Molecules In The Current State

After the liquid crystal electric field is removed, the liquid crystal molecules use their elasticity and viscosity to return to their previous state, that is, the way they were before they emitted light.

LCD currently has three backlight sources: EL (electroluminescence), CCFL (cold cathode fluorescent lamp) and LED (light emitting diode).

Since the first two types have certain defects, they have been gradually replaced by LED backlights. An interesting question even arises: Is an LCD using an LED backlight an LCD or an LED? Those who are interested can think about it.

Structure

LEDs currently come in two common forms, one is plug-in and the other is surface-mounted. Although they look different in form, the structure and principle are the same. All are achieved by sealing the luminescent material in a container. After the power is turned on, a light source will be generated.

The Composition Of LED Display
The Composition Of LED Display

LCD is a little more complicated. It needs to put liquid crystal material into the laminated glass, and then in order to make it shine, a reflector with a light source needs to be placed on the back to provide backlight for the liquid crystal.

The Composition Of LCD
The Composition Of LCD

Summary of the first paragraph

We analyzed the differences between LED VS LCD from three aspects: material, light-emitting principle and structure. Finally, we were surprised to find that LCD now incorporates some LEDs, and the two have become inseparable.

LED VS LCD Advantage Comparison

In the previous chapter, we introduced that liquid crystal itself does not have the conditions to emit light, so we chose finished products to compare the advantages of LCD vs LED.

Contrast

Contrast is the brightness at the whitest moment/the brightness at the darkest moment. Judging from the test data, LED performs better than LCD. Even if an LCD uses an LED backlight, according to the law of conservation of energy, there will always be more or less loss when reflecting the light source, so LED is better than LCD.

Resolution

The LCD needs to be set before leaving the factory, and cannot be changed after it is set. LEDs can be spliced according to actual needs, and it is difficult to distinguish between the two. From the perspective of flexibility, LED is better, and from the perspective of simplicity, LCD is better.

Color gamut width

Wide color gamut is a color backlight technology. The international standard is that the color coverage reaches NTSC92%. The wide color gamut color coverage of most LCD screens on the market is between 92% and 109%, while the wide color gamut color coverage of LED displays is 110%. The wide color gamut color coverage of LED is slightly higher. 

Screen thickness

This LCD beats the LED completely. The LCD, including the frame, can still be 8-10 mm thick, while the splicing modules in most LED displays are 5 cm thick and require additional cabinets to function properly. Installed, the average thickness reached 20 cm.

Although a few types of LED displays (such as transparent LED displays) do not have the thickness of modules, they still have the thickness of a box, so there is still a certain gap compared with LCDs.

Energy saving

Energy saving is the strength of LED, and it is precisely for this reason that only the LED backlight remains among the three commonly used LCD backlight sources.

Service life

The average service life of LEDs is about 11 years, but LCDs only have a service life of 7–9 years.

Cost

This is one of the few strengths of LCD. For the same 100-inch display screen, if the LED display screen wants to achieve the clarity of LCD, the cost will be 3–5 times. 

In other words, if a 100-inch LCD screen costs 2,000 US dollars, then the LED display screen will cost at least 6,000-10,000 US dollars. US dollars.

Technology maturity

At present, both of them have experienced more than 10 years of development, and their technical maturity is very high, and they can achieve various customized effects.

Summary of the second paragraph

We analyzed the advantages of LED and LCD from multiple aspects such as contrast, resolution, wide color gamut, price, etc. We can find that although LED almost completely beats LCD, there is still an insurmountable gap in the field of small display devices.

Application Area

Indoor Application

Monitoring room

Monitoring Room With LED Display
Monitoring Room With LED Display

Because LED displays have better display effects, more flexible performance, and strong integration, many monitoring rooms have replaced LCDs with LED displays.

Meeting room

The Conference Room Uses A Smart LCD For Function Display
The Conference Room Uses A Smart LCD For Function Display

Compared with the monitoring room, the conference room does not have high requirements for screens. In order to save costs, the conference room still mainly uses LCD equipment.

TV

Smart LCD Manufactured Using LCD Panels
Smart LCD TV Manufactured Using LCD Panels

Although LED display screens can be used as rear-projection TVs, and LED materials can also be used to customize TVs, they are much more expensive than LCD TVs, so LCD TVs are still the mainstream.

Outdoor Application 

Most of the outdoor advertising market is covered by LED displays, leaving only some platforms and stores using LCDs. On the one hand, these scenes do not have high requirements for display, and on the other hand, the scene area is not large. , the use of LED displays is overkill.

The Outdoor LED Display Is Playing Advertisements
The Outdoor LED Display Is Playing Advertisements

Advantages of LED display in outdoor applications

  1. Flexible splicing: LED displays are very flexible in splicing, and in theory, as long as you have enough money, you can even have unlimited splicing. This kind of flexible splicing can well meet different outdoor areas.
  2.  Low maintenance cost: Once there is a problem with the LCD, the entire screen often needs to be replaced, but the usually LED only has a certain LED module failure. At this time, you only need to replace it with an LED module of the same model to display normally. . The maintenance cost will be much lower than that of LCD.
  3. High brightness: Due to strong sunlight outdoors, the brightness of ordinary display devices is not high enough, which will cause the screen to become blurry. However, the LED display can reach a brightness of 7000 or even 8000, so it does not affect the viewing experience under the sun. .
  4. Waterproof: If the LCD is placed for outdoor use, the entire screen needs to be completely enclosed with glass or acrylic plates, otherwise the screen will be easily damaged due to water intrusion. The LED display screen is specially designed for outdoor use. From the LED module to the LED box, it is designed to be waterproof and hydrophobic, which can effectively prevent rainwater from penetrating and causing screen damage.

Summarize

The above is the detailed introduction of LED vs LCD. We have conducted detailed analysis from many different angles. I believe that the above article can help you distinguish the difference between the two.

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