Digital television

Digital television (DTV) is the sending and receiving of moving images and sound by means of discrete (digital) signals, in contrast to the analog signals used by analog TV. Introduced in the late 1990s, this technology appealed to the television broadcasting business and consumer electronics industries as offering new financial opportunities.

Digital television is more flexible and efficient than analog television. When properly used by broadcasters, digital television allows higher-quality images and sound and more programming choices than analog does. However a digital signal does not necessarily carry a higher-quality image or sound than an analog signal.

Formats and bandwidth

With digital television, two formats–HDTV and SDTV–of TV programs are broadcast.

High-definition television (HDTV), which is usually used over DTV, uses one of two formats: 1280 × 720 pixels in progressive scan mode (abbreviated 720p) or 1920 × 1080 pixels in interlace mode (1080i). Each of these utilizes a 16:9 aspect ratio. (Some televisions are capable of receiving an HD resolution of 1920 × 1080 at a 60 Hz progressive scan frame rate — known as 1080p60 — but this format is not standard and no broadcaster is able to transmit these signals over the air at acceptable quality yet.)

Standard definition TV(SDTV), by comparison, may use one of several different formats taking the form of various aspect ratios, depending on the technology used in the country of broadcast. For 4:3 aspect-ratio broadcasts, the 640 × 480 format is used in NTSC countries, while 720 × 576 (rescaled to 768 × 576) is used in PAL countries. For 16:9 broadcasts, the 704 × 480 (rescaled to 848 × 480) format is used in NTSC countries, while 720 × 576 (rescaled to 1024 × 576) is used in PAL countries. However, broadcasters may choose to reduce these resolutions to save bandwidth (e.g., many DVB-T channels in the United Kingdom use a horizontal resolution of 544 or 704 pixels per line).^[1] The perceived quality of such programming is surprisingly acceptable because of interlacing—the effective vertical resolution is halved to 288 lines.

Each DTV channel is permitted to be broadcast at a data rate up to 19 megabits per second, or 2.375 megabytes per second. However, the broadcaster does not need to use this entire bandwidth for just one broadcast channel. Instead the broadcast can be subdivided across several video subchannels of varying quality and compression rates, including non-video datacasting services that allow one-way high-bandwidth streaming of data to computers.

A broadcaster may opt to use a standard-definition digital signal instead of an HDTV signal, because current convention allows the bandwidth of a DTV channel (or “multiplex“) to be subdivided into multiple subchannels, providing multiple feeds of entirely different programming on the same channel. This ability to provide either a single HDTV feed or multiple lower-resolution feeds is often referred to as distributing one’s “bit budget” or multicasting. This can sometimes be arranged automatically, using a statistical multiplexer (or “stat-mux”). With some implementations, image resolution may be less directly limited by bandwidth; for example in DVB-T, broadcasters can choose from several different modulation schemes, giving them the option to reduce the transmission bitrate and make reception easier for more distant or mobile viewers.

Reception

There are a number of different ways to receive digital television. One of the oldest means of receiving DTV (and TV in general) is using an antenna (known as an aerial in some countries). This way is known as Digital Terrestrial Television (DTT). With DTT, viewers are limited to whatever channels the antenna picks up. Signal quality will also vary.

Other ways have been devised to receive digital television. Among the most familiar to people are digital cable and digital satellite. In some countries where transmissions of TV signals are normally achieved by microwaves, digital MMDS is used. Other standards, such as DMB and DVB-H, have been devised to allow handheld devices such as mobile phones to receive TV signals. Another way is IPTV, that is receiving TV via Internet Protocol, relying on DSL or optical cable line. Finally, an alternative way is to receive digital TV signals via the open Internet. For example, there is a lot of P2P Internet Television software that can be used to watch TV on your computer.

Some signals carry encryption and specify use conditions (such as “may not be recorded” or “may not be viewed on displays larger than 1 m in diagonal measure”) backed up with the force of law under the WIPO Copyright Treaty and national legislation implementing it, such as the U.S. Digital Millennium Copyright Act. Access to encrypted channels can be controlled by a removable smart card, for example via the Common Interface (DVB-CI) standard for Europe and via Point Of Deployment (POD) for IS or named differently CableCard.

Types of media

Standard 35mm photographic film used for cinema projection has higher resolution than HDTV systems, and is exposed and projected at a rate of 24 frames per second. To be shown on television in PAL-system countries, cinema film is scanned at the TV rate of 25 frames per second, causing an acceleration of 4.1 percent, which is generally considered acceptable. In NTSC-system countries, the TV scan rate of 30 frames per second would cause a perceptible acceleration if the same were attempted, and the necessary correction is performed by a technique called 3:2 pull-down: over each successive pair of film frames, one is held for three video fields (1/20 of a second) and the next is held for two video fields (1/30 of a second), giving a total time for the two frames of 1/12 of a second and thus achieving the correct average film frame rate.

Non-cinematic HDTV video recordings intended for broadcast are typically recorded either in 720p or 1080i format as determined by the broadcaster. 720p is commonly used for Internet distribution of high-definition video, because all computer monitors operate in progressive-scan mode. 720p also imposes less strenuous storage and decoding requirements compared to both 1080i and 1080p. 1080p is usually used for Blu-ray Disc.

HDTV sources

The rise in popularity of large screens and projectors has made the limitations of conventional Standard Definition TV (SDTV) increasingly evident. An HDTV compatible television set will not improve the quality of SDTV channels. It will make it even worse because of scaling artifacts. To display a superior picture, high definition televisions require a High Definition (HD) signal. Typical sources of HD signals are as follows:

• Over the air with an antenna. Most cities in the US with major network affiliates broadcast over the air in HD. To receive this signal an HD tuner is required. Most newer high definition televisions have an HD tuner built in. For HDTV televisions without a built in HD tuner, a separate set-top HD tuner box can be rented from a cable or satellite company or purchased.
• Cable television companies often offer HDTV broadcasts as part of their digital broadcast service. This is usually done with a set-top box or CableCARD issued by the cable company. Alternatively one can usually get the network HDTV channels for free with basic cable by using a QAM tuner built into their HDTV or set-top box. Some cable carriers also offer HDTV on-demand playback of movies and commonly viewed shows.
• Satellite-based TV companies, such as Astra (in the Netherlands), Premiere (in Germany), DirecTV and Dish Network (both in North America), Sky Digital and freesat (in the UK and Ireland), Bell ExpressVu and Star Choice (both in Canada) and NTV Plus (in Russia), offer HDTV to customers as an upgrade. New satellite receiver boxes and a new satellite dish are often required to receive HD content.
• Video game systems, such as the PlayStation 3 and Xbox 360, and digital set-top boxes that rely on an Internet connection, such as the Apple TV, can output an HD signal. The Xbox Live Marketplace, iTunes Music Store, and PlayStation Network services offer HD movies, TV shows, movie trailers, and clips for download, but generally at lower bitrates than a Blu-ray Disc.
• Most newer computer graphics cards have either HDMI or DVI interfaces, which can be used to output images or video to an HDTV.
• The optical disc standard Blu-ray Disc (25GB-50GB) can provide enough digital storage to store up to 10 hours of HD video content, depending on encoder settings.^[9]
• A DVD-R disc (~4.7GB-9GB) can also provide storage for 20-40 minutes of HD video content, readable by a Blu-ray player, PlayStation 3 video game console or Blu-ray drives installed on PC towers, depending on encoder settings.

The rise of digital compression

As soon as the MPEG1 standard provided the foundation for digital TV, development of modern TV standards started worldwide. After finalization of MPEG2 in mid 1993, the DVB organisation within the International Telecommunication Union’s radio telecommunications sector (ITU-R) developed the ETSI standard 300-327 by the end of December 1993.

It became known as DVB-T for digital terrestrial TV. DVB-S and DVB-C standards soon followed for terrestrial, satellite and cable transmission of SDTV and HDTV. In the USA the Grand Alliance proposed ATSC as the new standard for SDTV and HDTV. Both ATSC and DVB were based on the MPEG2 standard. The DVB-S2 standard is based on the newer and more efficient MPEG4 compression standards. Common for all DVB standards is the use of highly efficient modulation techniques for further reducing bandwidth, and foremost for reducing receiver-hardware and antenna requirement.

In 1983, the International Telecommunication Union’s radio telecommunications sector (ITU-R) set up a working party (IWP11/6) with the aim of setting a single international HDTV standard. One of the thornier issues concerned a suitable frame/field refresh rate, with the world already strongly demarcated into two camps, 25/50Hz and 30/60Hz, related by reasons of picture stability to the frequency of their mains electrical supplies.

The WP considered many views and through the 1980s served to encourage development in a number of video digital processing areas, not least conversion between the two main frame/field rates using motion vectors, which led to further developments in other areas. While a comprehensive HDTV standard was not in the end established, agreement on the aspect ratio was achieved.

Initially the existing 5:3 aspect ratio had been the main candidate, but due to the influence of widescreen cinema, the aspect ratio 16:9 (1.78) eventually emerged as being a reasonable compromise between 5:3 (1.67) and the common 1.85 widescreen cinema format. (It has been suggested that the 16:9 ratio was chosen as being the geometric mean of 4:3, Academy Ratio, and 2.35:1, the widest cinema format in common use, in order to minimise wasted screen space when displaying content with a variety of aspect ratios.)

An aspect ratio of 16:9 was duly agreed at the first meeting of the WP at the BBC’s R & D establishment in Kingswood Warren. The resulting ITU-R Recommendation ITU-R BT.709-2 (“Rec. 709“) includes the 16:9 aspect ratio, a specified colorimetry, and the scan modes 1080i (1,080 actively-interlaced lines of resolution) and 1080p (1,080 progressively-scanned lines).

It also includes the alternative 1440 x 1152 HDMAC scan format. (According to some reports, a mooted 720p format (720 progressively-scanned lines) was viewed by some at the ITU as an “enhanced” television format rather than a true HDTV format^[4], and so was not included, although 1920×1080 and 1280x720p systems for a range of frame and field rates were defined by several US SMPTE standards.)

History of high-definition television

The term high definition once described a series of television systems from the 1930s and 1940s, starting with the British 405-line black-and-white system introduced in 1936, and including the American 525-line NTSC system established in 1941. However, these systems were only “high definition” when compared to earlier systems.

All such so-called high definition systems were based on the Thorn-EMI electrical system, as opposed to the Baird et al mechanical systems. The BBC approved the Thorn-EMI system for national use by the summer 1937.

A brief itemized history of early analog HD systems follows; these would be considered standard definition television systems today.

• 1936: System-A, UK: 405 lines @ 50 hz, discontinued 1986
• 1938: Several countries used a 441 line system, France in 1956 being the last to discontinue it
• 1939: System-M, USA: 525 lines @ 60 hz
• 1952-1956: European adoption of 625 lines @ 50 hz with PAL and SECAM color coming in 1956
• 1956: French (monochrome) 819 line @ 50 hz system launched, discontinued 1986

All used interlacing and a 4:3 aspect ratio except the 405 line system which started as 5:4 and later changed to 4:3.

The post–WWII French 819-line black-and-white system was high definition in the contemporary sense, but was discontinued in 1986, a year after the final British 405-line broadcast. Neither the 405 line nor the 819 line television system supported color transmission in any form.

Since the formal adoption of DVB’s widescreen HDTV transmission modes in the early 2000s the 525-line NTSC (and PAL-M) systems as well as the European 625-line PAL and SECAM systems are now regarded as (so called) standard definition television systems.

Epson Develops High-resolution 3D LCD

Set aside those oversized wayfarer-style goggles, Epson has developed a (QVGA) “high-resolution” (not really), autostereoscopic 3D liquid-crystal display. That’s just fancy way of saying 3D HDTV without the glasses.

You may have noticed 3D is making a comeback and it looks better than ever. Today you can see groundbreaking 3D effects in blockbusters like Journey to the Center of the Earth and they’re looking better than ever. Gone is the green and red film-lenses-in-cardboard in favor of much more sophisticated plastic polarized lenses that fit right over your glasses. The new technology produces the effect in much greater detail that we’d ever seen watching The Creature From the Black Lagoon in 3D at the matinee. But what if we could ditch the glasses once and for all? That’s a trick Epson says they’re making reality.

The race has been on among top display companies to produce a promising 3D display without the glasses. LG, Westinghouse Samsung and others have been in the race for 3D displays. Epson has just upped the stakes with a new type of LCD display. Epson says it’s development prototype presents sharp, vivid 3D images over a wider viewing zone than previously possible. We’re not sure how vivid this can be with 320×240 resolution, but we’ll at least cheer on the advancements in technology.

Epson lays claim that its technology rises above the competition because of its superior viewing zone, meaning you can view its 3D effects at higher resolutions and from a wider viewing angle. The company wants to make its 31-32.5 mm view width a standard in the 3D display industry.

But seeing this device at market is one of those details that can only be seen in the distant future – at any resolution. So far, all Epson has is a prototype and has provided no evidence of its cost or timeframe for its release.

So Which Display Technology is Best?

LCD vs. Plasma Screen TVs: The Flat Picture

As I mentioned above, the Plasma TV has the edge in terms of cost per size and black levels. While refresh rates used to be better in plasma displays, LCD panels are now fast enough to really turn this into a non-issue. Plasma also remains a less expensive option for larger display sizes though we see this cost-crossover size increase with every new LCD manufacturing plant that opens. LCD displays continue to drop in price as they increase in terms of quality and black level reproduction and contrast. Once this happens, Plasma may lose its edge and LCD technology could win out – at least in terms of mass market appeal. Note: “could”, “might”, “may”… you get the idea… We might be going back and forth a long time – which is only to our advantage. As many of the CRT manufacturing plants are slated to close or convert over to LCD (Sony announced the closing of two more CRT plants in the first quarter of 2006 alone), you can imagine that the technology as a whole will benefit from smarter, more efficient manufacturing processes. Add to this the en-mass entry of Korean manufacturers who are willing to lose money on panels in order to gain market share (being subsidized by your government is a good thing) and you’ve got a wild commodity environment for LCD. As this goes on, prices will continue to drop and the LCD market will likely drive even larger flat panel display products into the homes of consumers. 50-inch LCD displays are now quite affordable whereas 30 inch versions were expensive just a couple years ago.

DLP vs. LCD vs. LCOS Rear Projection Televisions

This is where the competition gets interesting. This is essentially a battle between Texas Instruments and all of the LCD manufacturers (Sony, Philips, Toshiba, Samsung). Many companies are hedging their bets on this one (Samsung manufactures all 3), however the real winner will be the one who can produce the best picture at the lowest cost. My bet is on DLP. DLP is releasing its 1080p chips and has increased black levels and contrast ratios with its new DC3 (Dark Chip 3) technology. The advances in DLP both current and forthcoming are exceptional, but so is LCOS which is essentially a densely-packed LCD – creating a finer picture without any of the “screen door” artifacts found in many LCD displays. Still, DLP’s reluctance to allow 3-chip pricing to hit “mere mortals” means that rainbow effect is still a concern for many.

3LCD rear projection does have some advantages, however. It is being developed further and further and will benefit from rapid price drops as manufacturing ramps up and technologies improve. Right now you can find large, HD-ready LCD-based RPTVs for under $1500. A similar DLP or LCOS version (currently) will tend to cost you around $500 – $1000 more. 3LCD front projection is fantastic at the proper viewing distances, however DLP seems to be quickly eating up the entry level projector market (Optoma’s HD70 brings 720p DLP into the sub-$1000 price category for the first time). The emerging LED backlight technology, replacing color wheels on DLP and bulbs on all of the rear projection sets will only enhance the color reproduction and shelf life of all three technologies.

The Cost Factor: How Much Do I Spend?

How much do you have? Seriously, though, budget and intended use will determine the direction you take in what technology you choose. Those with the strictest budgets will want to break into HDTV via LCD rear-projection or DLP/LCD front projection. We really no longer recommend CRT-based RPTVs as they represent a dying technology and we feel the advantages they once had are now far outweighed by the digital competition (die, convergence, DIE!)

If you are desperate for a flat panel, it’s going to be a question of size. LCDs cost more than Plasma TVs at the larger sizes (50-inches and up). The reason for this is production yields and undersupply. There is currently a condition of undersupply for many sizes of LCD displays due to the number of manufacturing plants available and the current configuration of those plants. Couple this with lower yields on larger display sizes due to burned out pixels and quality control, and you have a demand situation which forces LCD prices way up for displays over 42-50″. A fair estimate would be that at and above 50″ an LCD TV could cost 20-30% more than a comparable Plasma display. If you want the benefits of LCD above this size you will have to pay for it – and you thought Plasma was expensive!

If you are made of money and want the biggest flat panel around, Samsung and LG have been battling it out for years. I used to give the models and sizes of these TVs, but it’s become such a joke (they almost never ship – at least not in quantity) that we’ll just say they make big TVs. In addition, these oversized flat panels are priced at… well, more than you want to know.

So, as always, the choice is up to you. Spend your money wisely, and keep your eyes peeled for the new technologies as they break into the marketplace. Competition is always good and should do well to make all the technologies strive for better performance and lower costs to the consumer.

	OLED	DLP	LCD	Plasma
Contrast Ratio	very high	very high	medium	high
Typ. Brightness	600+ cd/m2	750+ cd/m2	700 cd/m2	1000†† cd/m2
Longevity (hours)	TBD	2-4k (lamp)	30k**	30k**
Burn-in	No	No	No†	Yes
Viewing Angle	160°+	170°	160°+	170°
Fully Digital Display	Yes	Yes	Yes	Yes
Refresh Rate	< 6ms	NA	< 12ms*	< 8ms
Max Resolution	1080p	1080p*	1080p	1080p*
Weight (lbs)	lightest	medium	light	medium
Set Depth	< 1-2″	6.5″ – 24″	2″+	3″ – 7″
Screen Size	< 10″	43″ – 73″*	< 82″*	< 103″*
Power consumption	Very Low	Medium	Low	Medium
*Fairly new development noticed at CES 2006 ** Expected LCD backlight lifespan or plasma half-life; note: differs from manufacturer claims †† Plasma “real-world” measurements after calibration are considerably lower

	LCOS/DILA	RP LCD	SED	CRT
Contrast Ratio	medium	medium	highest	highest
Typ. Brightness	750+ cd/m2	450 cd/m2	400 cd/m2	300 cd/m2
Longevity (hours)	2-4k (lamp)	2-4k (lamp)	TBD	20k+
Burn-in	No	No	No	No†
Viewing Angle	180°	170°	180°	180°
Fully Digital Display	Yes	Yes	Yes	No
Refresh Rate	< 8ms*	< 8ms*	< 2ms	NA
Max Resolution	1080p	1080p	1080p	1080i
Weight (lbs)	medium	medium	medium	heavy
Set Depth	24″ – 30″	13″ – 20″	< 4″	16″ – 30″
Screen Size	< 82″	< 70″	TBD	< 42″
Power consumption	Medium	Low	Low	High
*Fairly new development noticed at CEDIA 2006 † Fixed images can result in burn-in over long-term (unusual)

SED Surface-conduction Electron-emitter Display Technology

Technology Overview & Description

SED, or Surface-conduction Electron-emitter Displays are a new, emerging technology co-developed by Canon and Toshiba Corporation. The hope for this technology is a display which reproduces vivid color, deep blacks, fast response times and almost limitless contrast. In fact, if you take all of the claims made by the backers of SED you would think that there should be no reason to buy any other type of display. A long life filled with bitter disappointments and lengthy product-to-market times have increased my skepticism and lowered my tendency to act as a cheerleader until products start to hit the market. As far as the specs go, this is one hot technology.

An SED display is very similar to a CRT (and now we come full circle) in that it utilizes an electron emitter which activates phosphors on a screen. The electron emission element is made from an ultra-thin electron emission film that is just a few nanometers thick. Unlike a CRT, which has a single electron emitter that is steered, SEDs utilize a separate emitter for each color phosphor (3 per pixel, or 1 per sub-pixel) and therefore do not require an electron beam deflector (which also makes screen sizes of over 42″ possible). Just for clarity that means a 1920 x 1080 panel has 6.2 million electron “guns”. The emitter takes roughly 10V to fire and is accelerated by 10kV before it hits the phosphor lined glass panel. Sound like a lot of power? It’s all relative as a typical SED display is expected to use about 2/3 the power of a typical plasma panel (and less than CRTs and LCD displays).

OK, here’s the real interesting news. SED display electron emitters are supposed to be printable using inkjet printing technology from Canon while the matrix wiring can be created with a special screen printing method. The obvious result is the potential for extremely low production costs at high volumes once the technology is perfected.

What’s Next?

Canon debuted an SED display prototype at the la Defense in Paris in October 2005. The specs referenced a < 1ms response time, 100,000:1 contrast ratio, brightness of 400 cd/m^2, and 180 degree viewing angle in all directions. Actual shipping models are expected to fist be released by Toshiba in 2007. Pricing is expected to be less than LCD and plasma for the same size – we’ll see.

SED Display Advantages

• CRT-matching black levels
• Excellent color and contrast potential
• Relatively inexpensive production cost
• Wide viewing angle

SED Display Disadvantages

• Unknown (though optimistic) life expectancy
• Potential for screen burn-in
• Currently prototype only

OLED Technology (also AM OLED, PM OLED, SM OLED, PLED & LEP)

Technology Overview & Description

Organic Light-emitting Diode displays (OLEDs) represent, like SED displays, a very promising format for use in home theater. The contemporary technology was developed by Eastman-Kodak and works via electroluminescence whereby a bright light is emitted whenever current is applied to conductors surrounding organic thin films. These displays do not require backlighting and can be manufactured in very thin, compact designs. Viewing angles are expected to be at least 160 degrees in all directions and operation occurs with just 2-10 volts. There is a lot of confusion within OLED technology however, as there are multiple manufacturing methods and technology approaches. As such, we’re waiting a bit for the industry to shake itself out and see which technologies will take off for each application type.

AM (Active Matrix) OLEDs seem to be the technology of choice when it comes to the types of displays that will make it into the home theater environment. In an AM OLED, the OLED pixels are placed onto a TFT (thin film transistor) array backplane which functions as a series of switches to control the current flowing to each of the pixels. Typically there are two TFTs at each pixel, which results in a the ability to have a constant current flow and eliminating the need for power-hungry current spikes as in passive OLED technologies.

A potentially more exciting form of the technology (though likely not home theater-related) is more commonly referred to as PLED (Polymer Light-emitting Diodes) or LEP (Light-emitting Polymers) whose emissive materials can be applied using techniques derived from commercial inkjet printing (thanks to Seiko Epson and a 30 micron printing process). This technology was developed by Cambridge Display Technologies (CDT). The end result is that these displays can be made in a very flexible (literally) and cost-effective manner. LEPs are very closely related to LEDs however instead of using a semiconductor material to produce light, LEPs use a 2-layer polymer.

What’s Next

AM OLEDs and LEPs are both positioned to take over LCD displays – though the fruition of this endeavor remains to be seen. Both OLED technologies promise several advantages including: elimination of backlighting, requiring a single layer of plastic as opposed to two sheets of glass, lower power consumption, and the possibility for physically flexible displays. They also face significant challenges in the area of life expectancy and color consistency over the life of the display. Samsung demonstrated a 21″ (1920 x 1080) prototype AM OLED display in January 2005 as well as a 40″ (1280 x 800) prototype AM OLED display in May 2005. The 40″ unit boasted 600cd/m^2 brightness, 5000:1 contrast ratio, 80% NTSC color gamut, and a panel depth of just 3cm. At CES 2007 they were nowhere to be found (on-site anyway). With LCD and plasma prices dropping and technology advancing, OLED has its work cut out for it.

OLED Display Advantages

• Excellent brightness
• Great color and contrast potential
• Relatively inexpensive to manufacture
• Thin, lightweight & durable
• Fast response time
• Eventually have capability of being physically flexible or rollable (LEPs)

OLED Display Disadvantages

• Short life expectancy (especially blue)
• Differing life expectancies for each color resulting for potential of color shift over time (needs to be controlled via electronics)
• Currently prototype-only for larger screen sizes – most OLED displays are for portable devices

LED Backlight Display Technology

Technology Overview & Description

A new technology player was in town this year at the 2006 CES. LED technology debuted as a future digital display backlight option that promised intensely saturated colors, the end of bulb replacement for rear projection displays, and increased color reproduction for direct view LCD televisions . It will also make you chicken soup if you are sick (OK, we added that part.) While the life expectancy of the LEDs was not fully addressed to my satisfaction (to convince us that bulbs will truly be a thing of the past), the color saturation does indeed look to be very impressive. The Sanyo model we saw, for example was absolutely stunning and boasted displaying 120% of the NTSC color gamut. Currently there are models being shipped by some (Sony’s QUALIA 005 for example), and prototyped by others – including Samsung, Sanyo, HP, JVC, Akai, Mitsubishi, and InFocus, and others have indicated upcoming use of this technology as well. Texas Instruments is excited about it and mentions the technology on their DLP website. Do you get the feeling that this LED thing is taking off? We’ll see. For one, their color extension claims are dubious at best. Not many panels that I’ve seen demonstrate 75% coverage of the NTSC chromacity spectrum – more like 90%.

What’s truly impressive about this technology is that it promises to do several things very well. One, it works with multiple rear projection technologies, including rear projection DLP, LCD, LCOS/D-ILA/SXRD and even palm-sized front projectors. Secondly, it promises to eliminate bulb replacement (100,000 hour LED life claimed – though we guess real world is more like 20-40,000) while providing better color reproduction at the same time. Thirdly, it eliminates warm up time and color instability since LEDs are pretty much instant on. It also functions, in Direct-LED systems, as a replacement for the fluorescent backlight in LCD flat panels. These features alone are worth the price of admission – which looks to be high for now, but only until volume sales begin sometime in 2007 (according to our sources). Samsung seems to be at least one of the companies leading the way on this.

What’s Next?

DLP TVs will almost invariably go the route of LED technology as it eliminates the color wheel and one more moving part. As for other technologies it’s a no-brainer that increases the shelf life of the backlight system and improves color – making products more competitive. I would suspect that even many LCD flat panels wil be replacing their fluorescent backlight systems with LEDs once the panel depths get better and the technology gets more affordable through mass production. Look for manufacturers to start bragging about color instead of contrast next year as this easily marketable feature takes off during 2007.

LED Backlight Technology Advantages

• Exceeds NTSC color gamut
• Excellent life expectancy (replaces typical 6000 hour bulbs in lamp systems)
• Replaces color wheel on DLP displays
• When used as LCD backlight, allows for execptional black levels
• “Instant-on” systems with almost no warm-up time.

LED Backlight Technology Disadvantages

• Expensive as “new technology” though expected to drop in price once it ships in quantity
• Panel depth for flat panel systems is a tad large at present in order to allow for combining of red, green, blue LEDs to make white.