Start shopping around for monitors, TVs, or digital signage and you’ll encounter two very similar acronyms right away — LED and LCD. This can be confusing, as you might see these terms used prominently in marketing or on packaging without any explanation as to what they mean. Not to mention, these acronyms have become shorthand for much more complicated concepts as well, which can make it even harder to know what you’re buying when looking for a display.
In this article, we’ll define these acronyms, talk a little bit about how modern screens work, and hopefully give you a little more knowledge and confidence when it comes to buying a digital display.
LCD stands for Liquid Crystal Display. So, what are liquid crystals? Brace yourself for this, because we’ll need to get a bit into the weeds. Liquid crystals are substances that have the physical properties of both liquids and solid crystals. When it comes to liquid crystal displays (LCDs), there is a layer of this liquid crystal substance inside the screen that makes it possible to show complex images. Don’t worry, that’s about as technical as we’ll need to get. Just remember that it’s the most common type of screen technology for electronics right now.
While the topic of LCD screens has become more popular in recent decades thanks to the rise of affordable LCD televisions and computer monitors, this technology has been around longer than you might think, and you only need to look around your house to find countless everyday examples.
The little display on your microwave, that calculator you still have from math class, even that old-school digital watch — all of these are LCD screens. They’re much simpler, but they work on the same principle as your 4K TV and your computer monitor. Importantly, liquid crystals don’t produce any light on their own, so LCD panels need a separate light source, or backlight, to show images, but we’ll come back to that later.
LED stands for Light Emitting Diode. Basically, it’s a very small electrical component that lights up a certain color when you pass electricity through it. LEDs are everywhere — household light bulbs, flashlights, those electric Open/Closed signs in store windows, the string lights on your patio, the small colored indicators on your keyboard (like the one that lights up to tell you that you left the Caps Lock on) — if you see a little colored light on something, it’s probably an LED.
When it comes to digital displays, LEDs are also used as backlights for LCD screens.
This is where manufacturers have had to simplify terms to express a pretty complex idea. Unfortunately, this has complicated the topic for consumers who understandably think that the LED TVs they see advertised at electronics stores are totally different from LCD TVs. There are “true LED” displays that are made up exclusively of colored LEDs, but that’s not what you see in consumer electronics most often. We’ll cover those later on.
In general, if you see an LED screen for sale to consumers, it’s actually an LCD screen with an LED backlight. A more appropriate name would be “LED-backlit LCD,” but that’s a mouthful. You can see why manufacturers choose to go with a simpler term. If you recall that liquid crystals don’t produce any light on their own, it makes sense that they would be paired with an LED panel to create the light they need to show an image.
LCD panels didn’t always use LEDs as a light source. They used to use CCFLs or Cold Cathode Fluorescent Lamps, a type of fluorescent lighting similar to those long white tubes you’d see lighting up hospitals, office buildings, and grocery stores. These were bulkier and less efficient, so they’ve been all but abandoned nowadays in favor of LED backlighting.
Yes. Direct view LED displays use an array of many, many tiny colored LEDs mounted to a panel to show vivid, bright, full-color images. You’ll see them most often used as signage in very large formats. Electronic billboards, big storefront signs, that giant four-sided scoreboard hanging over the basketball court, and wall-sized screens that show information or advertisements in airports and other public spaces are just a few examples. They need to be viewed from farther away, which is why they don't work well as televisions or phone screens.
If you’re wondering about OLED (Organic Light Emitting Diode) screens, just remember that they are mostly relegated to consumer electronics like televisions and smartphones. While technically “true LED” displays, they are a different technology than those used in large-scale, direct view LED screens.
The biggest issue with direct view LED displays is resolution, or how densely packed the individual light elements (or pixels) are. If you find one of these signs in the wild and walk right up close to it, the image will become difficult to see. You’ll be able to notice the individual pixels and the spaces between them, which destroys the illusion of one cohesive image.
That’s why you’ll want to look at pixel pitch, which is the distance between one pixel and the next, measured in millimeters. The closer together they are, the higher the resolution, and the clearer the image from up close. For enormous billboards that are viewed from very far away, a larger pixel pitch works well, commonly about 26mm. Other signs are smaller and meant to be seen much closer. An LED panel sign that measures about 40” x 90” might have a pixel pitch of 3.9mm, which —s passersby to view a crisp, clean image at about 22 feet away.
Of course, a denser pixel pitch means more LEDs, which translates to a higher cost. It’s critical to know how your display will be used and how close you expect viewers to get.
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