posted on Aug, 28 2011 @ 01:57 PM
In today's world of rapidly developing technology, it would seem as though there's a new TV display technology coming out every year accompanied
with its own alphabet to add to the soup. What is the difference between LCD and LED? Or CRT and Plasma? More importantly, what does it mean to
-you- and your TV-watching preferences?
1.0: The Basics.
An entire book could be written on the history of display technologies and the electronics behind them. Suffice to say that TVs started out as an
expansion of Radio. The electronics were nearly identical, spare for some additional stages used to isolate the picture. This signal, effectively,
told the TV how to reproduce an image on its screen.
For several decades, a Cathode Ray Tube was -the- display. This blast from the past creates a stream of electrons that are then deflected by magnetic
coils along a 'track' (a series of horizontal lines, coated in phosphorus) that makes up the front of the display. When the beam hits the
phosphorus, the electrons excite the phosphorus, causing it to glow. By breaking the beam's movement into discrete steps, the screen can be treated
as a grid of cells, each assigned their own brightness. This is, more or less, what a "pixel" is - one of the cells within this grid that makes up
This was pretty cool, and all, but but you could only have one 'color' (white). It didn't take too long for more complex Cathode Ray Tubes to be
developed that could support multiple electron beams and hit smaller sub-pixels made to glow specific colors. This remained the top display method
for many decades to come, with advances in technology making them lighter, more efficient, and larger in size.
1.1: So, what happened? Why do we have so many different displays, now?
Cathode Ray Tube (CRT) technology has its limits. It's a vacuum tube, something people my age never really had to mess with. Vacuum tubes only work
in a vacuum, as the name would suggest. This requires thick, heavy glass to hold the vacuum, as well as thousands of volts to operate. They are big,
heavy, and leave their mark on your electric bill.
As people got accustomed to radios that could fit in their pockets and computers that sat on a desk; all things made possible by solid state
technology (the transistor... there was a day when radios used to be marketed by how many transistors they had in them); it was only a matter of time
before display technologies took a similar route and migrated away from vacuum tubes.
2.0: Who's Who in Whoville?
There are several types of TV displays marketed. There are even more that are or have been in research, that I will not bother covering at this point
CRT: Cathode Ray Tube. The CRT is becoming much more rare in today's market, but is popular in the 'bargain' markets and gaming enthusiasts. CRTs
still possess some of the fastest display capabilities, which minimizes 'ghosting' and other blurring effects when displaying fast-paced
environments, such as games.
Rear Projection TVs: You don't see these very often, anymore. For the most part, an image is generated and then projected onto a screen. The
display technologies inside has varied widely, from CRT-bases to PDP and some others. The displays are slimmer than CRTs of comparable size, and
usually lighter. The front screen is often quite fragile and care should be taken to avoid damage. There is also considerable 'glow' or 'halo'
to many displays of this type.
PDP: Plasma Display Panel. To be honest, I've never seen "PDP" used in the marketing or labeling of a Plasma TV. The Plasma display is,
essentially, a gridded system of colored florescent/neon lights. Plasma is, basically, never seen in displays smaller than 32 inches, as production
is not cost-effective. Plasma displays are popular with display enthusiasts as they currently offer the greatest color range, contrast, and response
time (speed of the display) of mass-marketed displays. However, the screen is susceptible to burn-in and will dim over time.
LCD: Liquid Crystalline Display. The prime competitor to PDP technology. LCDs operate by manipulating the properties of crystals with electric
current. Electricity can be used to disrupt the structure, allowing for light from a back-light to be passed/blocked by the cell. While light and
affordable, LCDs have long endeavored to improve response time and true contrast ratios (the back-light must be blocked in order to create dark
scenes). Exactly how severe these discrepancies are varies by individual preferences. It is also worth noting that LCD encompasses a number of
sub-varieties not discussed here - for example, my laptop's LCD display is a little different from your TV's LCD display - but the fundamental
technology is still the same.
LED-LCD: Light Emitting Diode back-lit Liquid Crystalline Display. Typically marketed as "LED" - this display type is virtually identical to LCD
TVs except the florescent back-light has been replaced with white Light Emitting Diodes. It is important to note that each pixel is not a miniature
LED (much to my disappointment when doing my research on the display). Some of the higher-end sets have segmented back-lighting that can be
individually varied to further improve contrast (let's say you have one corner of the display that needs to be dark but the middle needs to be
bright-as-day). This display generally represents a marked improvement over plain-Jane LCDs.
OLED: Organic Light Emitting Diode. This form of display has only -just- seen market activity. Essentially, organic compounds are used to create
tiny light-emitting diodes on ... just about anything, really. Each cell is its own cache of light-emitting diodes. As such, there is no back-light.
The display can be made flexible (IE: "roll up") and is the thinnest, lightest display technology currently offered. While currently the most
expensive of displays in its class, it offers the greatest color range, contrast, and response times of all displays. Its primary drawback is the
volatility of the organic compounds, which break down in Ultra-Violet light and degrade over time (particularly the blue). It is, however, expected
to succeed both Plasma and LCD technologies in the future. QD LED (Quantum Dot Light Emitting Diode), or QLED is yet a further enhancement to OLED
technology that will likely appear in the coming years (though whether or not it will be marketed as QLED or just quietly phased in under the OLED
banner cannot be known).
2.1 So... What's best for me?
You are really only going to be able to decide that for yourself. However, here are some things to consider:
The size of your room. I've not met many people who like having to turn their head to see something toward either side of the TV. I've also not
met many people who like to feel like they are 'reaching through space' to focus on the TV. This is also going to relate to what you have available
in regards to stands/mounts. While a CRT may be cheaper to put into your room for personal use - you may find it far more practical to place a more
expensive LCD that takes up far less room.
What you plan to do with your TV. If you're just watching the news, Discovery, History, etc - you don't really need to have top-of-the-line color
gamut, contrast, and screen response. Further, displays susceptible to burn-in should not be used in applications where they are going to be
displaying static images for long periods of time (such as security displays or programs with static borders). Gamers and video enthusiasts will
likely go for the faster, higher-contrast displays (such as Plasma) - sports fans will likely find they prefer similar displays.
The times. OLED is poised to succeed both Plasma and LCD display technologies. It may very well be that, in a couple years, there will be little/no
sense in purchasing realistically obsolete technology. Sometimes you may be better served by holding off on a purchase for a few months to a year in
order to take advantage of new market offerings.
See it for yourself. It is almost always preferable to actually see what the display looks like before actually buying it. It's even better if you
can see what it will look like when displaying the types of scenes you will most often use it for. If you notice - most stores run slower, calmer
scenes on their TVs - this is likely due to many reasons, not the least of which being an attempt to avoid vexing customers wandering by a wall of
displays showing vertigo-inducing sequences. In many cases, this may be less than practical. However, you should at least check out reviews of that
particular model. Chances are there are some people who are using it similar to how you would, and have said a thing or two about how satisfied they
are with it.
3.0 The Future?
Basically, the future is shaping up to look like OLED and variations thereof. However, we are seeing some pretty interesting developments in lasers
and holographic display technologies. I don't expect we will see any of those come to market within the next 5 years, but you never know. CRTs will
likely still be around in their current market segment.
Projectors are seeing much wider use in fields of education and industry, and we may see some spill-over into the home entertainment market. That's
one I don't see being particularly wide-spread, but may certainly have some interesting applications (turning a wall into an alternate scene of some
sort, for instance - perhaps not a TV-related use, but more of an atmospheric/decorating tool).
E-ink displays being used by a number of specialized reading devices (Kindle, Nook, etc) may see some spill-over into the portable market. I can't
help but imagine my laptop with a large E-ink display on the cover (back of the screen) displaying my course-book or some other reading material. For
those interested - those displays are -very- similar to paper-and-ink. I generally do not like to read much on the computer as it tends to strain my
eyes in ways that reading from a book does not. These displays are electronic, but much easier on most people's eyes. I won't get into how they
work - but if you do a lot of reading, they are worth looking into.
4.0 Research, "lost," and Just-over-the-Horizon technologies?
Those interested can discuss and share below, as well as elaborate upon the running display technologies. There are simply too many branch and
'would have been' technologies to practically cover.