Q: When I read your article about OLED vs LCD TVs, I was puzzled. LCD does not exist anymore. When was the last time you saw an LCD TV for sale? I would say around 2010. I bought one in 2005. Three years later, I had to change the bulb for $120, and again three years after that. So, when it was about to die again, I bought an LG 55″ LED TV. I still have it, and it has not cost me anything for repairs over six years.
My question is, why do you call a Sony XBR an LCD TV when it’s an LED TV?
– Mike Lafortune
A: I’m really glad you asked this question! It highlights a serious misconception in the TV industry, one that manufacturers have encouraged with their misleading nomenclature. The term “LED TV” as it’s used today really means an LCD TV with LED backlighting.
The LCD TV you bought in 2005 was a rear-projection TV (RPTV) that used small LCD panels to form the picture. It used a bulb or lamp as the light source, and it needed to be replaced every few years, just as you experienced. In addition to LCD imagers, some RPTVs used DLP imagers, and a few used LCoS imagers. So, the complete and accurate name for such a TV should have been LCD RPTV, DLP RPTV, or LCoS RPTV. You bought an LCD RPTV in 2005.
You are correct that RPTVs of all types have completely disappeared. Now, all we have are flat-panel TVs, and there are two types: OLED and LCD. These terms refer to the technology of the imaging panel. In an OLED TV, each pixel consists of three sub-pixels—red, green, and blue—and these sub-pixels emit light directly when stimulated by an electric current. As a result, OLED is called an emissive display technology.
In an LCD TV, each pixel also consists of RGB sub-pixels, but in this case, the sub-pixels become more or less opaque when stimulated by an electric current. This allows more or less light to pass through them from the backlight located behind the LCD panel itself. In the graphic above, you can see the various layers within an LCD TV; the backlight is labeled “Light source,” and its light passes through all the other layers, including the liquid-crystal layer. Thus, LCD is called a transmissive display technology.
In the early days of LCD flat-panel TVs, the backlight consisted of several fluorescent tubes, much like the fluorescent lights in many offices, only much smaller. Now, the backlight in virtually all modern LCD TVs consists of LEDs. Many manufacturers took to calling these models LED TVs, probably because they thought the term was more appealing and modern-sounding than LCD TV. But it’s misleading.
Recently, Samsung introduced its QLED TV branding. This term refers to an LCD TV with LED backlight that incorporates quantum-dot technology—hence the “Q”—to achieve a wider color gamut and higher peak brightness. It’s a conventional LCD TV with an unconventional backlight. This technology is certainly not exclusive to Samsung; other manufacturers also use quantum dots in the backlight of their LCD TVs.
To reiterate, an LED TV is actually an LCD TV with LED backlighting. In an attempt to reduce confusion, I call it an LED-LCD TV. However, since virtually all LCD TVs now use LEDs in their backlights, it seems unnecessary to spell out this fact. On the other hand, it might be helpful for shoppers to know whether or not a TV uses quantum dots in its backlight, since QD technology offers several advantages over conventional LED backlights. So, maybe it would be best to use the terms LED-LCD TV and QLED-LCD TV.
At recent CES and CEDIA trade shows, several companies have demonstrated video displays in which the imaging panel consists of tiny LEDs that directly emit their own light. Examples include the Sony CLEDIS (Crystal LED Integrated System) and Samsung Cinema Screen. This is the only type of display that can rightly be called an LED TV.
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