LED vs CCFL TV lifespan? failure rate? - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 37 Old 09-25-2009, 03:33 PM - Thread Starter
Member
 
avdigger's Avatar
 
Join Date: Sep 2009
Posts: 165
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
I saw a lot of saying LED backlight TV is supposed to have longer lifespan than CCFL TV, but all these saying are just "supposed" based on theoretical assumption. Any official quote or number from any TV manufacturers? I found longer lifespan seems not a strong marketing point by the TV manufacturers. They really not mention too much about longer lifespan when they talk about LED backlight TV. That makes me wonder maybe there is not too much advantage in term of lifespan of a LED TV vs CCFL TV in actual usage.

In actual usage, lifespan is one thing, but the failure rate is another thing. Since the LED backlight uses an array of LEDs, so if any one of the LEDs (or its driving circuit) is dead, the whole TV is dead. From this point of view, the LED TV might be even easier to have problem than the CCFL TV because CCFL TV only has one (or two) CCFL bulbs while the LED TV has tons of LEDs.

Any thoughts?
avdigger is offline  
Sponsored Links
Advertisement
 
post #2 of 37 Old 09-25-2009, 05:37 PM
Member
 
turbo3's Avatar
 
Join Date: Sep 2005
Posts: 166
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 10
Just read the specs. Some LED TVs have shorter lifespan, uses more power, weighs more and costs a lot more than the CCFL counterpart. Be careful what you buy.
turbo3 is offline  
post #3 of 37 Old 09-25-2009, 07:42 PM
AVS Special Member
 
chdwil's Avatar
 
Join Date: Jul 2009
Posts: 1,074
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Aren't ccfl bulbs replaceable?

I would think that other problems would arise with most of the current sets available before backlight failures arise.
chdwil is offline  
post #4 of 37 Old 09-25-2009, 08:28 PM
AVS Special Member
 
davegow's Avatar
 
Join Date: Jan 2005
Location: In the glorious open countryside of Eastern Ontario.
Posts: 1,686
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
It's really too soon to come to final conclusions. Flourscent tube technology is far older and more mature than LEDs. Indeed, TV-quality LEDs are only a couple of years old and more important the technology is evolving rapidly. In such a situation it's really difficult to pin down hard numbers.

I have no doubt that in the long run LEDs will take over, unless something comes along that's even better, like SED or OLED might eventually become. That's simply because LEDs are solid-state, and that almost always triumphs in electronics.

I expect to get an LED TV to replace my 720p projection set, but I'm not in a hurry. Next year's LED sets should be a considerable advance over present ones. And cheaper too, as mass production ramps up, and start-up investment is written off.
davegow is offline  
post #5 of 37 Old 09-25-2009, 08:31 PM
Newbie
 
Chance_Stevens's Avatar
 
Join Date: Sep 2009
Location: Atlanta, GA
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I remember when Samsung's LED DLP HDTVs came out. The big draw was that the LED picture would be good for 100,000 hours. Even if you watched 10 hours of television a day, you'd get 10,000 days which is a lot longer than anyone I know has held onto a television.

People change TV sets like they change houses (every 3 - 5 years). Odds are that once you are ready for a new set, there wouldn't have been enough time to pass for something to fail.

Many are called, few stand up
Many are chosen, few choose correctly
Chance_Stevens is offline  
post #6 of 37 Old 09-26-2009, 02:49 AM
Advanced Member
 
Benny42's Avatar
 
Join Date: Jan 2009
Posts: 905
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by chdwil View Post

Aren't ccfl bulbs replaceable?

Yes, and so are LEDs.

In both cases the problem is not the possible defect itself but the cost of repair.
I bet that a lot of BLU (back light unit - of whatever technology) repairs are too expensive after a few years so the owner will want to take a look at new models anyway.
Even if he doesn't want to: A set with a successful BLU repair may experience a failure of another component. One should carefully calculate if a repair really is economical.

Quote:


I would think that other problems would arise with most of the current sets available before backlight failures arise.

From what I've seen most defects are either somehow related to the failure of the PSU or the inverter board. These are the boards where most of the heat is generated or higher voltages are at work (being switched, transformed, whatever).

Then there is the failure of the LCD drivers or anything else related to the LCD itself which produces funny patterns on the panel (I'm excluding physical damage as that can happen with any set).

Then there seem to be quite a few of sets where the picture processing unit - the main controller chip(s) - are affected. Colors are missing, the picture is mirrored or frozen, inputs may be fried etc.

There's a lot of stuff in a TV just waiting to fail - not just the BLU.

bye
Benny

bye
Benny
Benny42 is offline  
post #7 of 37 Old 09-26-2009, 09:28 AM
Advanced Member
 
notreally's Avatar
 
Join Date: Jan 2004
Location: Toto land
Posts: 591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
And the backlights are not your screw in type bulb, but a part of a larger whole. If you have a backlight issue, you may want to replace the set, rather than repair, because of cost.

If I knew for a certainty that a man was coming to my house with the conscious design of doing me good, I should run for my life.
Henry David Thoreau
notreally is offline  
post #8 of 37 Old 09-26-2009, 11:20 PM
Senior Member
 
display veteran's Avatar
 
Join Date: Sep 2009
Location: Southern California
Posts: 412
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
As of right now there is no conclusive history of LED vs. CCFL since the LED technology is so new. The real problem of both systems is that if one of the components (a single CCFL lamp or a single LED diode) fails. If one of the CCFL lamps fails to strike and turn on, the unit will shut down since it is unsafe to continue running the inverter circuits with an open line to one lamp.

LED backlit panels will vary depending on what structure they use to create the light. In local dimming structures where a RBGG array is used, each zone consists of an array of one red and blue LED along with 2 green. If any LED fails, that zone will produce the secondary color and will display a cyan, yellow or magenta spot on the screen. If all white LED’s are used, the zone will appear as a dark spot.

If the panel is edge-lit (such as the new Samsung and the upcoming Sony XBR10) an entire series of LED’s will become inoperative and the unit will shut down since this upsets the load on the inverter/converter circuits beyond its resonant design. The longevity of LED vs. fluorescent lamps is still an open debate.

The fluorescent lamp backlight design has reliable track record. As a rule, if your television does not suffer from a fluorescent backlight failure within its warranty period you should expect reliable performance from that point. Based on my observations of fluorescent backlit displays over the last 10 years you should achieve at least 10,000 hours from the lamps before they begin to exhibit noticeable color shift towards the magenta spectrum. This will alter the white balance settings of your display and can be compensated to a point. If the display comes on with a magenta contamination that slowly shifts to proper white balance it is a sure sign that the backlights have neared their end of useful life.

Those who think they know everything annoy those of us who do.
display veteran is offline  
post #9 of 37 Old 09-28-2009, 06:06 PM - Thread Starter
Member
 
avdigger's Avatar
 
Join Date: Sep 2009
Posts: 165
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by display veteran View Post

As of right now there is no conclusive history of LED vs. CCFL since the LED technology is so new. The real problem of both systems is that if one of the components (a single CCFL lamp or a single LED diode) fails. If one of the CCFL lamps fails to strike and turn on, the unit will shut down since it is unsafe to continue running the inverter circuits with an open line to one lamp.

LED backlit panels will vary depending on what structure they use to create the light. In local dimming structures where a RBGG array is used, each zone consists of an array of one red and blue LED along with 2 green. If any LED fails, that zone will produce the secondary color and will display a cyan, yellow or magenta spot on the screen. If all white LED’s are used, the zone will appear as a dark spot.

If the panel is edge-lit (such as the new Samsung and the upcoming Sony XBR10) an entire series of LED’s will become inoperative and the unit will shut down since this upsets the load on the inverter/converter circuits beyond its resonant design. The longevity of LED vs. fluorescent lamps is still an open debate.

The fluorescent lamp backlight design has reliable track record. As a rule, if your television does not suffer from a fluorescent backlight failure within its warranty period you should expect reliable performance from that point. Based on my observations of fluorescent backlit displays over the last 10 years you should achieve at least 10,000 hours from the lamps before they begin to exhibit noticeable color shift towards the magenta spectrum. This will alter the white balance settings of your display and can be compensated to a point. If the display comes on with a magenta contamination that slowly shifts to proper white balance it is a sure sign that the backlights have neared their end of useful life.

Thanks for your informative reply. I may stick with the CCFL models.
avdigger is offline  
post #10 of 37 Old 09-28-2009, 06:57 PM
AVS Special Member
 
MrBobb's Avatar
 
Join Date: Sep 2008
Posts: 3,253
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 27 Post(s)
Liked: 21
I would not buy LED-lit based on perceived longevity at this point.

But, I would buy LED-lit based on improved contrast... if they weren't so damn expensive.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
MrBobb is offline  
post #11 of 37 Old 10-01-2009, 12:02 AM
Senior Member
 
display veteran's Avatar
 
Join Date: Sep 2009
Location: Southern California
Posts: 412
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by MrBobb View Post

I would not buy LED-lit based on perceived longevity at this point.

But, I would buy LED-lit based on improved contrast... if they weren't so damn expensive.

It is a tough decision. I am currently enjoying a Sony KDL55XBR8 with RGB LED local dimming and I must say that it is quite an amazing picture. We'll see how long this amazing picture lasts.

Those who think they know everything annoy those of us who do.
display veteran is offline  
post #12 of 37 Old 10-01-2009, 02:28 AM
AVS Special Member
 
Extreme_Boky's Avatar
 
Join Date: Feb 2009
Posts: 1,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by MrBobb View Post

I would not buy LED-lit based on perceived longevity at this point.

But, I would buy LED-lit based on improved contrast... if they weren't so damn expensive.


Sharp CCFL's and LED models are very close in price.

It is MUCH cheaper to implement LED tubes as backlight source.... no need for mutiple high tension transformers, additional DC / AC switching, high tube voltage... what other companies are charging for their LED models (read SAMSUNG, and SONY - naturally...) is a crime!

Boky
Extreme_Boky is offline  
post #13 of 37 Old 10-01-2009, 06:07 AM
TNG
AVS Special Member
 
TNG's Avatar
 
Join Date: Apr 2006
Location: East Bay Area CA
Posts: 1,622
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Extreme_Boky View Post

Sharp CCFL's and LED models are very close in price.

It is MUCH cheaper to implement LED tubes as backlight source.... no need for mutiple high tension transformers, additional DC / AC switching, high tube voltage... what other companies are charging for their LED models (read SAMSUNG, and SONY - naturally...) is a crime!

Boky

While I see your point on the Edge Lit LED sets, those with LD and those with Tri-color LEDs with LD could be spendy just based on the control of the color LD. The Sharp XS1 is a example of this, and to a lesser extent the XBR8.
TNG is offline  
post #14 of 37 Old 10-01-2009, 04:34 PM
AVS Special Member
 
Extreme_Boky's Avatar
 
Join Date: Feb 2009
Posts: 1,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by TNG View Post

While I see your point on the Edge Lit LED sets, those with LD and those with Tri-color LEDs with LD could be spendy just based on the control of the color LD. The Sharp XS1 is a example of this, and to a lesser extent the XBR8.

True... locally dimmed LED arrays are expensive to implement and control.

Boky
Extreme_Boky is offline  
post #15 of 37 Old 10-01-2009, 09:54 PM
Senior Member
 
display veteran's Avatar
 
Join Date: Sep 2009
Location: Southern California
Posts: 412
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Extreme_Boky View Post

Sharp CCFL's and LED models are very close in price.

It is MUCH cheaper to implement LED tubes as backlight source.... no need for mutiple high tension transformers, additional DC / AC switching, high tube voltage... what other companies are charging for their LED models (read SAMSUNG, and SONY - naturally...) is a crime!

Boky

To the contrary, it is considerably more expensive to use LED's for backlighting and especially more so when local dimming is incorporated with tri-colored LED's. Even though the inverter circuits do not use the high voltage levels found in CCFL models they are still quite complex and expensive and cosume about the same power as CCFL. The use of local dimming reduces the power consumption because they are dynamic and most scenes contain a sufficient amount of dark areas.

To give you an example: The Sony KDL55XBR8 uses a total of 1792 LED's incorporated into 112 individual zones for local dimming. The "look ahead" processor to analyze the video for dimming control is quite sophisticated and expensive. In time all of this will drop in cost, as usual, but will always cost more to produce than fluorescent backlighting. The LED models that you see which are closer to CCFL models are the ones using white only LED's.

Those who think they know everything annoy those of us who do.
display veteran is offline  
post #16 of 37 Old 10-02-2009, 03:40 AM
AVS Special Member
 
Extreme_Boky's Avatar
 
Join Date: Feb 2009
Posts: 1,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by display veteran View Post

To the contrary, it is considerably more expensive to use LED's for backlighting

Completely opposite actually...

Quote:


and especially more so when local dimming is incorporated with tri-colored LED's.

what?...when??? When did I ever compared anything here in this thread with dimmable LED's????

Go back and read what I posted again!!!

Boky
Extreme_Boky is offline  
post #17 of 37 Old 10-02-2009, 04:01 AM
Advanced Member
 
bowmah's Avatar
 
Join Date: Nov 2006
Posts: 842
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 16
So does that mean LCD's with CCFL have a bulb inside? Do these need to be replaced like those older LCD projector TV's?
bowmah is offline  
post #18 of 37 Old 10-02-2009, 04:30 AM
AVS Special Member
 
chdwil's Avatar
 
Join Date: Jul 2009
Posts: 1,074
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by bowmah View Post

So does that mean LCD's with CCFL have a bulb inside? Do these need to be replaced like those older LCD projector TV's?

very different type of bulbs. The ccfl bulbs are not unplug and plug in like the projector bulbs. The bulbs in projectors burn so bright and hot that their lives are considerably shorter than ccfl. They burn so hot in fact that they are culprit for the Optical Block failures in so many Lcos, sxrd, and Lcd projection sets.

A direct view LCD set is far more likely to fail in an area other than the ccfl bulb.
chdwil is offline  
post #19 of 37 Old 10-02-2009, 04:30 AM
AVS Special Member
 
Bailey151's Avatar
 
Join Date: Apr 2006
Posts: 1,948
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 68
Quote:
Originally Posted by bowmah View Post

So does that mean LCD's with CCFL have a bulb inside? Do these need to be replaced like those older LCD projector TV's?

Yes they have a bulb, no it's not a consumable. It's not a "user replaceable" bulb like projectors - it can be replaced, but it's generally cost prohibitive.

CCFLs have a far longer MTBF than bulbs used in projectors, in the thousands of hours. Likely other parts will fail first.

Quote:
Originally Posted by Extreme_Boky View Post

Completely opposite actually...

I'd argue that it depends, if they're using high intensity LEDs it can get complicated & costs can add up. I'd wager that's one reason (although they hype it for the "cool thin" factor) for the move to edge lit = fewer LEDs & less complicated circuitry.

Low intensity LEDs are pennies retail, high intensity are dollars (like $7 for 107 lumens @ 350mA variety)..............the same cost scale would apply to manufacturers. Even though they'd being paying pennies on their scale the cost could be much higher than a CCFL which is fairly cheap.

It's just my opinion & it's worth exactly what you paid for it.
Bailey151 is offline  
post #20 of 37 Old 10-02-2009, 05:01 AM
Senior Member
 
obeck's Avatar
 
Join Date: Nov 2003
Location: Dahlonega, GA
Posts: 310
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I am going to agree and disagree with both sides.

SOME LEDs are dirt cheap. Others are very expensive. I have no idea what they are using in TV sets. Further, there is a wide variation in lumens-per-watt and the color(per input watt) of the LED in a given batch. I imagine that they have to be binned and very closely matched for LED backlighting applications.

I have had high $$$ LED flashlights for a while, and I can tell you that there was a visual difference even in the LEDs that were binned the same.

Thus, I can see that if you are using more expensive LEDs, and if you are using many and if they have to be an almost exact match, then LED backlighting could be more expensive even if the circuitry that controls them is much less complicated.
obeck is offline  
post #21 of 37 Old 10-02-2009, 06:05 AM
TNG
AVS Special Member
 
TNG's Avatar
 
Join Date: Apr 2006
Location: East Bay Area CA
Posts: 1,622
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
OK we all agree that Local Dimming and Tricolor sets have electronics that will be expensive, but the edge lit sets and the standard sets with LED BL and no dimming should be cheap.

I have not priced the parts, but I think that I could build one for less than $100. Even cheaper buying in bulk. A simple power supply, and distribution to LEDs mounted on what amounts to a board.
TNG is offline  
post #22 of 37 Old 10-02-2009, 02:17 PM
AVS Special Member
 
Extreme_Boky's Avatar
 
Join Date: Feb 2009
Posts: 1,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Why is almost everyone talking here about cost of LED tubes only???

CCFL tubes are pluggable… they are around 4-5 mm in diameter and plug in to sockets at both ends. One end is connected to high tension inverter output; the other end straight to TV metal frame which serves as current return path back to inverter board. This is latest implementation that makes them reasonably easy to replace. Older CCFL’s have wire tails attached to their ends…

LED tubes are slightly thicker and contain individual LED bulbs connected together. I am referring here to Sharp 77 CCFL series and 700 LED series. They are easier to drive – hence the core reason for cost savings (that everyone here is referring to – but taking in to account the cost of actual LED’s ONLY…)

LED arrays can do without a whole PCB module inside a TV. They consume approximately same amount of current but at very low voltage. This is the main reason for excellent power consumption result – very low compared to CCFLs:

CCFL’s require an extra “power supply” to produce high frequency and hight tension rails needed to ionise the gas inside them. This power supply (inverter) draws a lot of current at around 24 – 60V DC from the main power supply board. Inverter has to further switch this DC bus to produce AC bus at high frequency and high voltage (amplitude). These are all main reason for heat dissipation and unnecessary looses compared to LED arrays, which you can drive straight from the main power supply board. These facts should contribute to substantially lower cost in implementing full LED arrays vs. full CCFL arrays.

Edge lit LED’s should consume least amount of power and be by far the cheapest of them all – not the case according to Samsung pricing - they are ripping-off us consumers (well, not me in particular)…

Edge lit technology utilises quite heavily the light manipulation. Light generated by edge LED tubes is re-bounced number of times until it approaches the prisms (part of brightness enhancing fill sheets) at appropriate angle – in which case it will shoot straight thru the LCD panel at 90 deg angle. This technic can save around 60% of the original amount of light photons generated by actual light source. The brightness enhancing film sheets - even the highest quality ones - are cheap!!! So, why are we being charged by Samsung the premium price for edge lit LED models???...

Sharp approach is simply to replace CCFL tubes with LED tubes behind the full diffuser area. If an LCD TV needs 18 CCFL tubes, it may need 16 or less LED tubes to produce same backlight brightness. They achieve this goal AND manage to remove inverter board completely.

However, the main driving force behind LED implementation is NOT anything of the above…. It is a fact that CCFL generated backlight has very unpleasant green, and to the lesser extent blue push… the white is not really white... the light source contains higher quantities of light photons oscillating at around 660 nm (I think…. this is without going back and checking what the exact “green” wavelength is). This HAS TO BE compensated by LCD panels providing famous “red-push” that we all hate so much…

LED light source can be very easily taylored to produce “pure” white backlight source.

Enough from me….

Boky
Extreme_Boky is offline  
post #23 of 37 Old 10-02-2009, 09:43 PM
Senior Member
 
display veteran's Avatar
 
Join Date: Sep 2009
Location: Southern California
Posts: 412
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Extreme_Boky View Post

Why is almost everyone talking here about cost of LED tubes only???


CCFL's require an extra power supply to produce high frequency and hight tension rails needed to ionise the gas inside them. This power supply (inverter) draws a lot of current at around 24 - 60V DC from the main power supply board. Inverter has to further switch this DC bus to produce AC bus at high frequency and high voltage (amplitude). These are all main reason for heat dissipation and unnecessary looses compared to LED arrays, which you can drive straight from the main power supply board. These facts should contribute to substantially lower cost in implementing full LED arrays vs. full CCFL arrays.


Boky

I believe a little basic electronics is needed here. If you wish to generate 100 watts of power from a fluorescent lamp array you must first supply them with around 1000 volts of AC power. That translates to 0.10 amps (or 100 milliamps).

If you wish to generate 100 watts of power from an LED array driven by 24 volts the current draw will be 4.166 amps.

Both backlight types are drawing the same amount of power. It does not matter if an inverter is used to generate high voltage. Wattage is wattage no matter how you put it. There is a give and take whenever voltage is increased or decreased from the source voltage. This is one of the most basic laws of electronics. The only reason a high voltage inverter is used for fluorescent backlighting is because that is what they need in order to ionize the gas. The LED lamps do not require this voltage but the current is increased to achieve the same power consumption.

The power necessary for the LED backlights is created by a converter on the power supply board. Just because it is mounted on the same board does not mean that power is being saved over an external inverter.

The real issue here is how much light can be generated with a given power rating. If one type of backlight device gives off more lumens of light at 100 watts (this wattage is only being used as an example based on the comparisons above) the efficiency has been increased. That is what it is all about. Increase the efficiency of light output and the power requirements are reduced.

Those who think they know everything annoy those of us who do.
display veteran is offline  
post #24 of 37 Old 10-02-2009, 09:52 PM
Senior Member
 
display veteran's Avatar
 
Join Date: Sep 2009
Location: Southern California
Posts: 412
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Extreme_Boky View Post

LED light source can be very easily taylored to produce pure white backlight source.


Boky

I had to comment on this line too. If you are stating that a white LED can be taylored to produce pure white, this is not true. White LED's do not not generate an even gamut just as a fluorescent tube does not. They both have areas of the color spectrum in which they tend to enhance. Fluorescent lamps tend to spike in the green spectrum and white LED's in the blue. This is why the quality display panels use the RGB array. Photo sensors are used to balance the red, green and blue to achieve a wider color gamut.

Those who think they know everything annoy those of us who do.
display veteran is offline  
post #25 of 37 Old 10-03-2009, 01:31 AM
AVS Special Member
 
Extreme_Boky's Avatar
 
Join Date: Feb 2009
Posts: 1,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by display veteran View Post

I believe a little basic electronics is needed here. If you wish to generate 100 watts of power from a fluorescent lamp array you must first supply them with around 1000 volts of AC power. That translates to 0.10 amps (or 100 milliamps) .

If you wish to generate 100 watts of power from an LED array driven by 24 volts the current draw will be 4.166 amps.

Both backlight types are drawing the same amount of power. It does not matter if an inverter is used to generate high voltage. Wattage is wattage no matter how you put it. There is a give and take whenever voltage is increased or decreased from the source voltage. This is one of the most basic laws of electronics. The only reason a high voltage inverter is used for fluorescent backlighting is because that is what they need in order to ionize the gas. The LED lamps do not require this voltage but the current is increased to achieve the same power consumption.

The power necessary for the LED backlights is created by a converter on the power supply board. Just because it is mounted on the same board does not mean that power is being saved over an external inverter.

The real issue here is how much light can be generated with a given power rating. If one type of backlight device gives off more lumens of light at 100 watts (this wattage is only being used as an example based on the comparisons above) the efficiency has been increased. That is what it is all about. Increase the efficiency of light output and the power requirements are reduced.

I am glad to see that you learned something from my previous posts, but why are you constantly re-wording what I have written and using it to prove something. is beyond me.

You still don't understand where the saving in driving LED's is actually coming from. LED LCD TV's use 30% less power compared to CCFL's to produce the backlight of same intensity . And this fact is not related to OHMs law.

Boky
Extreme_Boky is offline  
post #26 of 37 Old 10-03-2009, 01:43 AM
AVS Special Member
 
Extreme_Boky's Avatar
 
Join Date: Feb 2009
Posts: 1,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by display veteran View Post

I had to comment on this line too. If you are stating that a white LED can be taylored to produce pure white, this is not true. White LED's do not not generate an even gamut just as a fluorescent tube does not. They both have areas of the color spectrum in which they tend to enhance. Fluorescent lamps tend to spike in the green spectrum and white LED's in the blue. This is why the quality display panels use the RGB array. Photo sensors are used to balance the red, green and blue to achieve a wider color gamut.

and now you are starting to get on my nerves... when did I say WHITE LED???

I wrote :”LED source” – not WHITE LED source

And yes, the LED source can be tailored to produce white backlight. This is what Sharp did in their latest 700 series…

The only explanation is that you are new to these forums and are trying to prove something (to yourself)…. Just avoid stating my post in the future please… you use them in completely wrong context which I find offending.

Boky
Extreme_Boky is offline  
post #27 of 37 Old 10-03-2009, 08:40 AM
Senior Member
 
obeck's Avatar
 
Join Date: Nov 2003
Location: Dahlonega, GA
Posts: 310
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
You guys are arguing to prove the same point... that LED is much more expensive than lining up a boatload of cheap LEDs and calling it a backlight.
obeck is offline  
post #28 of 37 Old 10-03-2009, 08:09 PM
Newbie
 
tcatx's Avatar
 
Join Date: Aug 2007
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hey! all on this thread !
This maybe off the subject somewhat, but what is your opinons on the following subject matter. We have what seems to be electronic /led experts onboard with good knowledge about electronic components.

The samsung 8500 thoughts.

1) Has led lighting by it's Samsung's propietory bright white led lighting array (as shown on their ad) both top and bottom and positioned "not" on the edge but on the flat panel itself. Could it employee directional Led's inbetween the top and bottom (one way firing top and bottom) of an led array and fire through lightpipes or light tubes?

Maybe more Led's ( two sided directional firing led's) are employed between top and bottom pipes ( for the 55" model) to ensure that constant light output is achieved and that local dimming can be better used by the fast switching of the led's current between the top and bottom led's ( or middle). The lightpipes or tubes have the ability to adjust the color wavelenths and to localy dim or turn off. (see or google the patent "flickerless backlight for a disply panel"
2) Samsung has said that the 8500 has full backlighting similar to the A950 but has not said that that it is a full array of led"s directly behind the liquid crystals with local dimming. This opens up the question as to what "similar" means. Direct led's backlighting or direct backlighting by color, fast switcing, Lightubes.

3) Lightpipes or tubes can achieve full backlighting unlike the edglight with full panel diffusers that "spread light" and don't have the direct, behind the pixel backlighting.

With color lighting coming from the the lightpipes and using a "black" background (behind the light pipes to dampen reflections) it seems that you should achieve excellent results. Seems this helps with panel lighting uniformity and saturation. You should get great color Color( behind the crystals color lighting), like the RGB led's used in the Sony xbr-8. You should also benefit from the use of local dimming withoutout the complications of higher power supplies and complex costly drivers and also achive higher light output.
4) Lightpipes or tubes are much less expensive and use less power than "full arrays of direct led backlighting with local dimming" let alone the additional cost of hardware and software drivers.
5) With the use of of new tech regarding Liquid crystals and the alignment of molecues, for clarity, contrast ratios, and fast responce, it seems that using unique backlighting in LCD's is dimminshing.
6) I don't know what the cost is to implement such new, diverse tech, but it seems that it would be less expensive, to produce, to operate on a daily basis, than a full array direct backlighting with local dimming with thousands of led's and hundreds of zones controlled by hardware and software drivers.

anybody's thoughts ?
tcatx is offline  
post #29 of 37 Old 10-03-2009, 11:48 PM
Newbie
 
tcatx's Avatar
 
Join Date: Aug 2007
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Samsung company and/or spokesman

I know that new tech competition is extremly competitive and critical and you must use all your survival skills and all your PR skills to promote your tech and company image.

You must satisfy your shareholders and investors. You are in the buisness to make profits. Sharp, Lg, Philips, Sony, Panasonic and others are right beside you.

Can you step forward and explain, like or unlike your competition, what exactly you are offering to the public (newest and best picture quality tech) with your newest releases, without having someone take apart your products to discover the electronics you implement ?
Why ? because people on this and other forums are more technically knoweldgeable than the casual in store grocery shoppers and may be able to promote or explain your fine products.

Best Regards
tcatx is offline  
post #30 of 37 Old 10-04-2009, 09:59 PM
Senior Member
 
display veteran's Avatar
 
Join Date: Sep 2009
Location: Southern California
Posts: 412
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Extreme_Boky View Post

and now you are starting to get on my nerves... when did I say WHITE LED???

I wrote :”LED source” – not WHITE LED source

And yes, the LED source can be tailored to produce white backlight. This is what Sharp did in their latest 700 series…

The only explanation is that you are new to these forums and are trying to prove something (to yourself)…. Just avoid stating my post in the future please… you use them in completely wrong context which I find offending.

Boky

Now I am going to give you a nervous breakdown.

When you say "LED source" and are not specifying a tri-color array, you are talking about a white LED. Why does my naming upset you so much when that is the correct technical term for this type of LED?

No, I am not new to the forums on the net, just this one. I've been working with this stuff for a long time. I am mainly here to provide technical help to those asking for it. If a duscussion pops up (such as this one) where there is incorrect information and/or clarification is needed, I might jump in for the heck of it. There is usually one person who wants to "spar" with me. I am not in this to prove anything to myself. I've already proven myself in this industry and just recently received an award for what I have contributed.

The original post asked about the longevity of LED versus fluorescent lamps and I responded appropriately by responding that the LED technology was too new to provide accurate data. You jumped in with power consumption opinions which had nothing to do with the original question.

To end this thread and answer the power consumption issue I took 4 different LCD models (of the same year) with different backlight sources and hooked them up to an amp meter. They were all set to maximum backlight output. This should prove my point.

40" with CCFL backlights: 1.56 amps = 188 watts
40" with HCFL backlights: 1.16 amps = 140 watts
40" with edge lit LED: 1.86 amps = 205 watts

The only tri-color backlit model I have is a 55" so this would not make a good comparison and I believe the no one makes a 40" tri-color anyway. Can we move on now?

Those who think they know everything annoy those of us who do.
display veteran is offline  
Reply LCD Flat Panel Displays

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off