LED TV and LCD TV (newbie)

Discussion in 'General Electronics Chat' started by NY10, Aug 20, 2010.

  1. NY10

    Thread Starter Member

    Jul 30, 2010
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    Hi,

    What is the difference between LED TV and LCD TV ?

    I would like to know electrical or electronics difference in detail.

    Thanks in advance.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. tom66

    Senior Member

    May 9, 2009
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    Usually, when a manufacturer of a consumer TV says "LED TV", they mean a traditional LCD TV backlit by white or RGB LEDs.
     
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  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    ^^yes. Just LED backlighting versus flourescent.
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I have one and there are several advantages. The contrast ratio is something like 2M:1 on mine, probably because they can better match the backlight frequency closer to what the LCD screen responds to. Theoretically nothing to burn out and they generate a lot less heat when in operation.

    Mine isn't the newest generation which also has the capability of modulating the backlight level to match lighter or darker areas of the picture.

    True "LED Pixels" have been produced in the lab but aren't practical yet. The color of the pixels would have to be exact and squeezing millions of LEDs onto a panel isn't a reality yet either. You will see it done on the absolutely huge displays though, those such as seen at a football stadium where 10801i resolution isn't a requirement.
     
  6. tom66

    Senior Member

    May 9, 2009
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    10801i resolution. I want to see a display with 10801 vertical pixels. Finally, a home cinema system with a greater resolution than the real world. :D
     
  7. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Read my signature line, I don't type well. Came from learning on a manual typewriter where you had to hammer on the keys and received a nice audible feedback with every letter, I also have to look at the keys when typing or I get lost real fast.

    As you can imagine, back when I had to program with punch cards on an IBM 26 or 29 keypunch I wasted a lot of cards. And if you think that was bad it was paper tape before that, not too easy to correct a single line on those.
     
  8. tom66

    Senior Member

    May 9, 2009
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    It wasn't intended as an insult, just as humour.

    I really would like to see one of those quad-4K displays. Not that I would ever need one. I can barely see the pixels on my 720p laptop screen at 3ft distance.
     
  9. marshallf3

    Well-Known Member

    Jul 26, 2010
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    This I realize.

    What really pisses me off is that there isn't a circuit on this thing that detects when a picture is obviously 16:9 but it only shows up small unless I press the Zoom button. I can understand 3:4 with the black on the sides and usually leave it that way because I don't like to artificially stretch things out, (makes people short and fat) but some things on Discovery or the History channel show as a small 16:9 box and have to be zoomed.

    You'd think a set could detemine if there was black both to the sides AND under/above a picture they could adjust accordingly.
     
  10. tom66

    Senior Member

    May 9, 2009
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    You'd think it would be simple. In fact such a circuit would be trivial; sync to the video signal, count lines and detect this. However, manufacturers want to lower the cost as much for themselves, so if they can save a few bucks on the more expensive chip which does this (or if the chip can do it but it is enabled by a 1k resistor for a $300 upgrade), they will. It also comes down to possible bugs in the system. You would need a long enough delay before switching over, otherwise dark scenes would falsely trigger it.
     
  11. retched

    AAC Fanatic!

    Dec 5, 2009
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    There would be no reason to count the lines. TV is broadcast in digital. The video header would have the resolution AND aspect ratio encoded. The display COULD EASILY switch to the video aspect.
     
  12. tom66

    Senior Member

    May 9, 2009
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    I think he is talking about double bars. Where the film production has bars on top, but is shown at 4:3, and your TV puts bars on the side, to show it at 16:9. Or something like that. Anyway, only the second set of bars can be eliminated by the TV.
     
  13. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I think it has to do with the program material being 720i or p yet the transmitter is sending out a 1080i signal so the set just displays it as bit for bit.

    Can't say that I've seen anything come in over the air as 1080p yet.

    The best HD "from the air" signals I've seen so far have come from PBS. I don't have a Hi-def cable in my bedroom/shop hideaway area but they give us the local stations in hi-def for free so long as you've got a box (or a TV that can tune in the 7xx channels as this one will) you can at least see them. I paid a ton for this 32" Sharp - LED or not - but it was the only model that would fit into the spot in which it has to reside.

    Anything other than a 32" would have been a step down in square inches of viewable picture at 3:4 when compared to the 27" Sony tube model it replaced, I actually lost a tiny amount. Yet TV isn't my life, it's more background material to me. I am however set up for when I eventually have to move into a place of my own again, currently my mother is 80 years old and needs a bit of help and companionship from time to time, being the only single child in the family it kind of became my duty. Doesn't kill me though, 3,400 sq ft 2 story house keeps plenty of distance between us and I've also got what was the game room as we grew up (23' x 24') at my disposal as an indoor shop area.

    When I do move I'm set with plenty of electronics. Harman-Kardon surround receiver driving huge JBLs and a few other stereos, several TVs, lots of tools and parts. My home network is a bit complicated though. One nice desktop & a laptop in my room along with a set of three PCs built to be a media server setup. MS1 is used to download and store program material, it has 500G of OS and 4.5 TB of RAID 5 storage. MS2 is simply a file server with 500G of OS and 14 TB of RAID5 storage upgradeable to 30 TB. MP1 handles all the playing and distribution, it has the high end graphics, sound, TV tuner and multi video IO in it. Most everything has dual Plextor Lightscribe DVDs in them along with the various card readers, the desktop even has two floppy drives and a 10K RPM Raptor drive to serve as the cache for the pagefile and various browsers. Printers upstairs and down. It's mainly hard wired with gigabit ethernet but I also have wireless N for the laptops. Obviously I like to build other things as well. :)
     
  14. tom66

    Senior Member

    May 9, 2009
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    ^^ I am jealous.

    Well, since we're discussing computers...

    My hard drive collection consists of: 1x 80GB WD Caviar HDD, 1x 40GB IBM DeskStar (which I have renamed "DeathStar") HDD, a 1TB external HDD, a Seagate 250GB SATA for my media PC, and my laptop's 250 GB HDD. So in total, about 1.5TB of storage, and I'm using less than 30% of this total. Oh, and a few spare external HDDs which don't get used much...

    I have a media PC, it runs Windows XP, which is unlike all my other PCs which run Ubuntu (including my laptop.) It's a Scaleo E and it has been the only computer I ever bought (all the others were bought for me, or given to me as "it doesn't work" when all it took was a replacement power supply or reseating the graphics card.) It cost me £119.99, that was on sale. It didn't include a HDD or ODD, so I bought the 250GB SATA drive for £29.99, and I had a spare DVD±RW PATA drive so I used that, but it is silent as nothing else (my laptop's fan is louder than its two fans) and has SCART RGB outputs for legacy TV. I have recently bought a graphics card for when we upgrade to high definition TV, as it only has integrated graphics and I suspect this will have difficulty at 720p or 1080p.

    Also, I have, in total about 6 computers. 5 desktops and a laptop. Only one desktop machine and my laptop is in use at the moment.
     
  15. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Hitachi drives only had a short period of sub-quality product in which they earned their nickname. I pretty much use them exclusively, I figure if they're good enough for Google to use in some of their servers they're good enough for me.

    If you keep an eye on NewEgg (be sure you're signed up for their newsletter) as well as http://www.mwave.com you can sometimes hit on a Hitachi 2 TB for $110 with free shipping. The 1 TB & 500G are also to be found at good prices, last I saw a 500G was $40 with free shipping on NewEgg.

    As with ANY brand of hard drive some people have trouble with them and others don't, it's the luck of the draw. There's also a lot of people that don't know how to properly install, format or deal with them in general. They try to play the game of plug and play then when that doesn't work they begin fooling with them not having a clue how to get them back to an out of the box condition to start over with so they submit all these reviews about them being junk whereas people like me just ut them to work and forget them.

    Onboard graphics is improving, 1080p isn't unusual, but never expect any sort of performance from an internal chip. They're fine for plain displays but for my media player I wanted something that would help co-process .avi and DVD stuff instead of taxing the CPU.
     
    Last edited: Aug 21, 2010
  16. boging

    New Member

    Aug 27, 2010
    1
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    why is it LED TV is more expensive than LCD
    I am newbie please guide . thank.
     
    Last edited: Aug 27, 2010
  17. tom66

    Senior Member

    May 9, 2009
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    Because manufacturers have decided it so. It would cost very little to include LEDs instead of CCFLs. In fact, it would probably cost more to include CCFLs+inverter circuitry instead of LEDs.
     
  18. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I think it's a bit more complex than that. I don't believe that the entire rear of the screen is a full mattrix of LEDs pixel by pixel, it's just a lot of them that have to be perfectly diffused so the brighness remains uniform in all areas.

    Anything new is expensive, they have to completely set up an entirely new "factory" so to speak to make products with a major change in design. They have to re-coup their costs somehow.

    The price will start dropping in time, California has been working on yet another green initiative limiting the power consumption a certain size TV can consume and at present LEDs are the only way to reach it.
     
  19. tom66

    Senior Member

    May 9, 2009
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    Well, when I was ordering my laptop, there was an option to select between a CCFL screen or an LED screen, at no cost. I chose the LED screen because of the better efficiency (longer battery life) and because it means my LCD hasn't got toxic mercury in it.
     
  20. marshallf3

    Well-Known Member

    Jul 26, 2010
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    It's got toxic something else in it then but you made a wise choice due to display life and power consumption. The batteries themselves are probably the most toxic part of a laptop to begin with.

    As a person with a fair amount of physics and chemistry background I get some good laughs about how overboard some of these ecologists can go.

    Did you realize that we as humans contribute virtually no mercury to the environment? 97% of it comes from existing volcanic activity.

    Recent emissions estimates of annual global mercury emissions from all sources, natural and anthropogenic (human-generated), which are highly uncertain, are about 4800-8300 tons per year.

    U.S. anthropogenic mercury emissions are estimated to account for roughly 3 percent of the total global emissions, and the U.S. power sector is estimated to account for about 1 percent the total global emissions.
     
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