Plasma and LCD TV: The Same, but Different
Outward appearances are deceiving when it comes to LCD and Plasma TVs.
Plasma and LCD TVs are flat and thin, and also incorporate many of the same operating features.Both can be wall-mounted and may offer the internet and local network streaming.Both offer up the same types of physical connectivity options.Both allow you to watch TV programs, movies, and other content in a variety of screen sizes and resolutions.
However, despite their similarities, how they produce and display images is quite different.
How Plasma TVs Work
Plasma TV technology is based loosely on the fluorescent light bulb.
The display consists of cells. Within each cell, a narrow gap that contains an insulating layer, address electrode, and display electrode, separates two glass panels. In this process, neon-xenon gas is injected and sealed in plasma form during the manufacturing process. When a Plasma TV is in use, the gas is electrically charged at specific intervals. The charged gas then strikes red, green, and blue phosphors, creating an image on the screen. Each group of red, green, and blue phosphors is called a pixel (picture element — the individual red, green, and blue phosphors are called sub-pixels). Since Plasma TV pixels generate their light, they are referred to as “emissive” displays.
Plasma TVs can be made thin. However, even though the need for the bulky picture tube and electron beam scanning of those older CRT TVs is not required, Plasma TVs still employ burning phosphors to generate an image. As a result, Plasma TVs suffer from some of the drawbacks of CRT TVs, such as heat generation and possible screen burn-in of static images.
How LCD TVs Work
LCD TVs use a different technology than plasma to display images.
LCD panels are made of two layers of transparent material, which are polarized, and are “glued” together. A specialized polymer that holds the liquid crystals coats one of the layers. Current passes through individual crystals, which allow them to pass or block light to create images. LCD crystals do not produce light, so they need an external source, such as fluorescent (CCFL/HCFL) or LEDs, for the picture created by the LCD to become visible to the viewer.
Since 2014, almost all LCD TVs employ LED backlights. Since LCD crystals do not produce light, LCD TVs are referred to as “transmissive” displays. Unlike a Plasma TV, since there are no phosphors that light up, less power is needed for operation, and the light source in an LCD TV generates less heat than a Plasma TV. There is no radiation emitted from the screen.
Advantages of Plasma Over LCD
Better contrast ratio and ability to display deeper blacks. Better color accuracy and saturation. Better motion tracking (little or no motion lag in fast-moving images due to Sub Field Drive Technology). Wider side-to-side viewing angle.
Disadvantages of Plasma vs. LCD
Plasma TVs are not as bright as most LCD TVs. They perform better in a dimly lit or darkened room.The screen surface is more reflective than most LCD TVs, which means they are susceptible to glare — screen surface reflects ambient light sources.Plasma TVs are more vulnerable to burn-in of static images. However, this problem diminished over the years due to “pixel orbiting” and related technologies.Plasma TVs generate more heat and use more energy than LCD TVs, due to the need to light phosphors to create images.Plasma TVs do not perform as well at higher altitudes.Potentially shorter display lifespan. Early models had 30,000 hours or 8 hours of viewing a day for nine years, which was less than LCD. However, screen lifespan improved and 60,000-hour lifespan rating became the standard, with some sets rated as high as 100,000 hours, due to technology improvements.
Advantages of LCD Over Plasma TV
No burn-in of static images. Cooler running temperature. No high altitude use issues. Increased image brightness over Plasma, which makes LCD TVs better for viewing in brightly lit rooms. Screen surface on most LCD TVs is less reflective than Plasma TV screen surfaces, making it less susceptible to glare. Lighter weight (when comparing the same screen sizes) than Plasma TVs of the same screen size. Longer display life, but the gap has narrowed.
Disadvantages of LCD vs. Plasma TV
The lower real-contrast ratio is not as good as rendering deep blacks, although the increasing incorporation of LED backlighting has narrowed this gap. Not as good at tracking motion (fast-moving objects may exhibit lag artifacts). However, this has with the implementation of 120Hz screen refresh rates and 240Hz processing in most LCD sets, but that can result in the “Soap Opera Effect,” in which film-based content sources look more like a videotape than film. Narrower effective side-to-side viewing angle than Plasma. On LCD TVs, it is common to notice color fading or color shifting as you move your viewing position further to either side of the center point. Although LCD TVs do not suffer from burn-in susceptibility, single pixels can burn out, causing small but visible, black or white dots to appear on the screen. Individual pixels are not fixable. Replacing the whole screen is the sole option if the pixel burnout becomes unbearable. An LCD TV was typically more expensive than an equivalent-sized (and equivalent featured) Plasma TV. However, that is no longer a factor, since companies have ceased manufacturing Plasma TVs.
The 4K Factor
Manufacturers chose to incorporate 4K resolution only in LCD TVs, using LED back and edge-lighting, and, in the case of LG and Sony, incorporating 4K into TVs using OLED technology. Although it was possible to incorporate 4K resolution display capability into a Plasma TV, it was prohibitively expensive. When the sales of Plasma TVs started declining, TV makers decided against bringing consumer-based 4K Ultra HD Plasma TVs to market, which was another factor in their demise. The only 4K Ultra HD Plasma TVs manufactured were for commercial application use.
The Bottom Line
Plasma has a distinguished place in TV history as the technology that popularized the flat panel, hang-on-the-wall TV.
