LCD TVs

[jtr1962]

A while back I started a thread after I broke my TV. I haven't bought one yet because my brother let me borrow his 27" until I saw one I liked. I initially was going to get a flat screen, and then when I saw the prices dropping I decided to wait for a CRT HDTV. Anyway, my dad recently purchased a 30" widescreen LCD HDTV (Westinghouse LTV-30w2) at Bestbuy for $1100 after rebate. I've been "borrowing" it while my dad cleans up and buys a cabinet.

I have to say I'm impressed. While I always would have preferred something flat (either plasma or LCD) over a bulky, heavy CRT the price difference was simply too high. Now I'm noticing that when on sale, 30" or so LCD TVs are only maybe $100 to $300 more than comparable CRT-based HDTVs. Furthermore. LCD seems to offer a huge advantage over plasma (and CRT for that matter). Backlight life is 50,000 hours. I can't imagine anything going wrong with the display itself unless subjected to impacts, vibrations, or temperature extremes. Basically then an LCD TV should last at least twice as long as any other type. The picture also looks great (and we're not even getting HD signals yet!). Are there any drawbacks to LCD TVs that I'm not aware of? I'm seriously considering going this route, in maybe the 32" or 34" size, once prices get into the $1000 or less range (I'll bet that happens in 6 months).

If/when LCD reaches price parity with CRTs, is there really any point to making CRTs any more? I heard using LED instead of fluorescent backlights should greatly increase the color gamut, if that is even an issue now. Another plus-without the strong electric field hitting the screen, you simply don't have the constant dust accumulation that CRTs always have.

BTW, this TV also has a VGA and a DVI connection for use as a PC display. I tried it-MS Train Simulator looks awesome. I'm thinking that I can double the LCD TV as a monitor rather than purchasing a new purpose-designed PC monitor. Any disadvantages to this (outside of the maximum resolution is 1024x768)?

 

[Mercutio]

The big problems with LCD sets basically come down to limited size, poor off-axis viewing and limited brightness. If you're happy with the size and brightness of the display then there really aren't any other issues.

Personally, I still prefer DLP/LCoS ("D-ILA") for my display. Both offer similar levels of brightness as well much larger screens. Both types cost more, and DLP sets have a bulb that needs to be replaced every few years, but the cost for either is rapidly shrinking to "reasonable" as well.

Also, if portability is truly a factor, you might find that you are better served with a projector rather than any kind of large conventional display.

 

[e_dawg]

Not a big fan of LCD or DLP when it comes to watching darker scenes (as appears on 24, CSI, Alias, movies, etc.) With HDTV signals and brighter scenes, LCD and DLP can look damn good, but it can also look stunningly bad if those conditions are not met. I have a Samsung 43" DLP RPTV and can't say I'm all that pleased with its performance on regular CATV or with any dark scene DVD, HDTV, or CATV. Most people I know with HDTV sets are also disappointed with regular CATV picture quality. Found similar problems (although not as bad) with the Sony Grand Wega III LCD RPTV and Sharp Acquos LCD flat panel display. Still find CRT RPTV and direct view TV has the best quality under all scene conditions.

 

[Handruin]

Rumor has it the newer samsung DLP's (HLRxx68W) will sport a 10,000:1 contrast ratio. This might help with the darker scense.

I haven't read the entire thread, it's 118 pages long. But it had some decent info to start.

 

[e_dawg]

It's not lack of sufficient maximal contrast that is the problem. My DLP set, like most of its ilk from the same vintage is vibrant and "pops" with contrasty images. Very excellent contrast. The problem is with the picutre quality of the darker scenes -- specifically, the gamma tracking and colour rendering.

Gamma tracking: (This is probably not technically accurate, but here goes...) This is basically how bright the TV in question makes the pixels or image in response to the luminance level of a given input signal. For example, the dark parts of a dark scene will have a luminance signal of 1.0 on a 10 point scale, and the resulting image will be very dark (the mirrors will respond in such a way that they will emit 10% of their max brightness). Brighter parts of that bright scene (say a face in the dark) will have a luminance signal of 2.0. The gamma curve might call for 18% max brightness from the mirrors, but what you might really want to see is 25% brightness to really be able to discern features on the faces.

But wait, there's more. This would be fine if nothing else affected our ability to perceive brightness coming from the screen. But there is: the lighting level of the room in which you're watching TV. For most people, they watch TV in a moderately well lit room. This level of ambient light will reduce the viewer's ability to see anything with dark scenes. So that 18% should really be 35% in a well-lit room. So what's the solution? Turn off your room lights? But then the bright scenes where it's 60% for dark areas an 90% for bright areas is blinding.

IMO, there's two problems here: 1. the gamma tracking is not set correctly from the factory for dark scenes even in dark rooms, 2. gamma tracking needs to be adjustable so that users can watch TV in rooms of varying degrees of brightness comfortably.

Colour Rendering: You may have heard of a phenomenon called "clay faces"? The colours are washed out and poorly rendered, especially in dark scenes. This is related to gamma tracking, but in this case, it is a case of improper tracking of the chrominance and luminance input signals to produce the proper level of hue, saturation, and luminosity mix. This is partly due to the limitations of the way in which colour is "produced" in the DLP light engine. DLP uses a segmented colour wheel to split light into its component colours. Earlier colour wheels had fewer segments and rotated at slower speeds, making it more difficult to get the right colour where it's needed. But I have heard that newer generation colour wheels with more/variable pitch segments and faster rotation still have trouble with colour rendering in dark scenes.

Perhaps the 6th or 7th gen DLP technology will fix these ails (we are on the 4th or 5th gen depending on how you look at it), but so far I cannot recommend it without reservation (LCD is not much better IMO). Maybe the newer LCoS or OLED technologies have more potential?

 

[jtr1962]

I'm not looking at DLP sets at all because I don't have the room (most are 40" or larger) and they look dark compared to a CRT or a backlit LCD. Brightness is a big concern to me since I sometimes have the main light on when I'm watching TV. The "main" ceiling light in my bedroom has 4 32W T-8 fluorescent tubes putting out ~10,500 lumens. It would easily wash out any DLP set I've seen. Not so with this latest LCD set.

Maybe the newer LCoS or OLED technologies have more potential?

If you're referring to pure color rendering ability, then you're probably right. In fact, just plain LCD can provide amazingly true color when backlit properly using LEDs. By using four or five different color LEDs chosen to give a spectrum very close to the D65 used as the industry standard you can get excellent color rendering and color accuracy. Hopefully this will appear in products in the not too distant future, if it hasn't already. One problem is the need to use some sort of feedback to drive the different LED colors at the levels needed to give the desired spectrum. This is necessary because of the variation in LED characteristics.

Regarding adjusting the image for different light levels, why don't TVs incorporate some sort of feedback circuit which measures room light, and adjusts brightness accordingly?

On another note, I've also read somewhere about directional sound. Has this made it into a commercial product yet? This seems like a great thing to have since it means you can turn the volume up yet not disturb someone sleeping in the next room.

 

[i]

Has anyone had any experience with the Syntax "Olevia" line of LCD televisions? Syntax is apparently a newcomer to the LCD TV industry (just a year old I think). I think they predominantly use LG-Phillips displays so some might run screaming from the room right now.

Their current sets look interesting, and I've read some very positive reviews, but it's the products they expect to launch this year (they mention them in their press release from January) that interest me the most. From that press release:

Syntax will also introduce its first 1080p HD-compatible 37-inch (LT37HVDP) and 42-inch (LT42HVE) models featuring 1920x1080 resolution, 1200:1 dynamic contrast ratios, 8ms typical response times and built in ATSC tuners...

An alternate 42 inch LCD TV was announced just recently on April 5th. Unfortunately, with an MSRP of $3699, I think it's a little out of my league.

Anyway, there are a variety of things I find appealing about their models, including their prices compared to the competition. Their widescreen sets also have genuine 16:9 aspect ratios (1366 x 768), unlike the 15:9 aspect ratios (1280 x 768) that so many other manufacturers have but lie about.

 

[e_dawg]

Regarding adjusting the image for different light levels, why don't TVs incorporate some sort of feedback circuit which measures room light, and adjusts brightness accordingly?

Some TV's had something like that. I recall my parents' Pioneer CRT RPTV having it. Didn't make much of a difference, though. I don't know if a simple shift in brightness level would work, though. I think you would have to incorporate some kind of manipulation of the gamma curves (and for each colour, no less) if you wanted to do it right.

On another note, I've also read somewhere about directional sound. Has this made it into a commercial product yet? This seems like a great thing to have since it means you can turn the volume up yet not disturb someone sleeping in the next room.

One of the problems with directional audio is that lower frequencies are omnidirectional. You would be able to "beam" audio with a horn-loaded speaker, but only from say vocal frequencies and higher. You wouldn't be able to do that to the bass frequencies.

But after Googling for a bit, I think I may have found exactly what you're looking for. This is a cool way to get around this problem, and perhaps represents the first breakthrough in terms of bringing a solution like this to the market. ATC's ultrasonic directional sound is being licensed by Sony, who sells a commercial ultrasonic directional loudspeaker such as the HSS R-220B. But it's $1,800 US.

 

[e_dawg]

Here is an excellent article I read on ultrasonic directional sound and its two competing inventors. Here is an excerpt that I think you (and especially Merc) would appreciate:

In high school and during breaks from college, while working part time for Bose, the Framingham, MA, loudspeaker manufacturer, Pompei took note of the limitations of traditional speakers. But, he says, executives at Bose "were not interested in hearing about the future of sound from a 20-year-old." After receiving his electrical engineering degree from Rensselaer Polytechnic Institute, he went on to get his master's in psychoacoustics at Northwestern University. He says it was there, in the mid-1990s, that he got the idea for using silent ultrasound as a way of producing audible sound. "I was considered a mad scientist," Pompei recalls.

He first demonstrated the basic principle at the MIT Media Laboratory. While completing his PhD at MIT in 2002, Pompei launched Holosonic, bootstrapping the company with just a few thousand dollars of his own research stipend money. Pompei's system "really does behave like a spotlight," says David Rabkin, vice president of technology at Boston's Museum of Science, which uses the system in an exhibit. "You point the beam at one person and light them up with sound. But once you step outside the beam, the sound drops off quickly."

 

[e_dawg]

Here is another excellent article and an excerpt:

[...] Over the past few years, mainly in secret, he has shown the device to more than 300 major companies, and it has slackened a lot of jaws. In December, the editors of Popular Science magazine bestowed upon HSS its grand prize for new inventions of 2002, choosing it over the ferociously hyped Segway scooter. It is no exaggeration to say that HSS represents the first revolution in acoustics since the loudspeaker was invented 78 years ago -- and perhaps only the second since pilgrims used ''whispering tubes'' to convey their dour messages.

[...]

As night must follow day, there are Defense Department applications. Norris and A.T.C. have been busy honing something called High Intensity Directed Acoustics (HIDA, in house jargon). [...] If used from a battleship, it can ward off stray crafts at 500 yards with a pinpointed verbal warning. Should the offending vessel continue to within 200 yards, the stern warnings are replaced by 120-decibel sounds that are as physically disabling as shrapnel. Certain noises, projected at the right pitch, can incapacitate even a stone-deaf terrorist; the bones in your head are brutalized by a tone's full effect whether you're clutching the sides of your skull in agony or not. ''Besides,'' Norris says, laughing darkly, ''grabbing your ears is as good as a pair of handcuffs.''

[...]

Norris prods his assistant to locate the baby noise on a laptop, then aims the device at me. At first, the noise is dreadful -- just primally wrong -- but not unbearable. I repeatedly tell Norris to crank it up (trying to approximate battle-strength volume, without the nausea), until the noise isn't so much a noise as an assault on my nervous system. I nearly fall down and, for some reason, my eyes hurt. When I bravely ask how high they'd turned the dial, Norris laughs uproariously. ''That was nothing!'' he bellows. ''That was about 1 percent of what an enemy would get. One percent!'' Two hours later, I can still feel the ache in the back of my head.

 

[jtr1962]

All I can say about this ultrasonic directional sound is WOW! 8) The applications seem virtually endless, and the physical principles certainly seem sound. Excellent reading, e_dawg! I long for the day I can buy a set of directional speakers and watch TV without disturbing those around me. Right now this product needs to hit critical mass. Once it does, we may well see the end of the conventional loudspeaker.

I also found the "I was considered a mad scientist" line amusing. It seems this is the path any inventor goes through when pushing a new invention. Or to paraphrase Gandhi: First they think you're crazy and ignore you, then they laugh at you when they think you might be on to something, then they fight you when it turns out you really did invent a better mousetrap, and then finally you win.