Why Do the FlexView Panels Go Dim Faster then Regular TFTs

[kurutta]

Several posts to this group have stated that the FlexView panels degrade in brightness (and perhaps in color) much more quickly then do the regular TFT panels. Does anyone understand why this is? That is, what changes -- the panel or the CCFL light source? Because the CCFL in IPS panels is no different then those used in plain TFT panels, I am guessing that the CCFL is not the problem.

I would like to get a feel how significant this problem is, because my current plan is to find a used T60 with an IPS panel.

[dr_st]

I do not know the underlying physical phenomena, but the dimming and yellowing is a known fact, and I've observed it on all Flexviews I've had - T42 and T60. Mine were all SXGA+ LG Philips panels, but I understand UXGAs are not different in this regard.

Back in the day, Flexview panels were rated 200 nits, where most other panels on contemporary Thinkpads were 150. So they started out brighter, but they did have a tendency to lose brightness.

In most cases, however, it is not crucial. While you will definitely see difference comparing a new screen to an old one, and perhaps a Flexview and a non-Flexview of the same age, it will be a very long time before the screen becomes hard to use.

I've just recently compared the Flexview on my T42 (~3 years old) with the TN screen on my 14" T60, which is ~1.5 months old (both screens were replaced under warranty for issues not related to brightness). The Flexview is noticeably yellower, and a bit dimmer. But the yellow tint only really shows in comparison to the other screen (which is more blue-pink), and the brightness is still way enough (in fact, in a dark room, I would have to turn it down a few notches).

A couple of years ago I had a rare opportunity to compare a new Flexview with a 18-month old one, on the same laptop type, side-by-side (I regret not having taken pictures). The old one was noticeably dimmer and noticeably yellower. But if I hadn't been comparing them side-by-side, I would not have noticed any flaw in the old screen.

[Harryc]

Just wanted to add that I believe the dimming/yellowing is probably common across all regular TFT LCD's as well, but nobody cares enough to take notice .

[dr_st]

Just wanted to add that I believe the dimming/yellowing is probably common across all regular TFT LCD's as well, but nobody cares enough to take notice .

I will take that as a challenge, and get more data points!

[pianowizard]

Just wanted to add that I believe the dimming/yellowing is probably common across all regular TFT LCD's as well

Of course all LCDs grow dim over time, but IPS screens do so at a faster rate. Among the Thinkpads I have owned, I typically set the TN ones at 4 or 5 notches of brightness (out of 7 notches), but 5 or 6 for IPS screens under similar lighting conditions because they were somewhat dimmer.

I have never owned an IPS Thinkpad long enough to monitor how the dimming progresses over several years, but I did pay attention to how the brightness of a colleague's SXGA+ IPS T60 changed over the course of ~4 years. The rate of decline was quite alarming.

I am less concerned about yellowing, because one can compensate for that by adjusting the color balance.

[dr_st]

Of course all LCDs grow dim over time, but IPS screens do so at a faster rate.

It's interesting to check whether it is true in general of IPS screens, or just the ones used in Thinkpads / laptops.

[fasteez]

According to this xbit article http://www.xbitlabs.com/articles/monito ... html#sect0 IPS matrix element design already causes a dimmer display, probably increase the "dimming" rate over time... just sayin.

I didn't know about the yellow tint, now I understand why my x41t has it.. tablet .. ips angles.. duh .. that was obvious.

[sjthinkpader]

IPS panels need brighter backlight. The CCF are driven harder so on the average, go dim sooner. I am not sure the yellowing is related. Yellowing may be caused by the various films inside the assembly such as polarizer and the color filter going yellow. This is more likely caused by UV light than the stronger backlight.

[kurutta]

Great. Lots of discussion. Just woke up so I am catching up with this thread.

fasteez suggested that IPS panels have greater attenuation and therefor the light source needs to work harder. I think this is the case. I have a NEC 26" IPS monitor and it's apparent that its panel has higher attenuation. This is inherent to IPS panels.

sjthinkpader figured that UV light played a role. Would this be UV light from the CCFL or from ambient light? The glass envelope of the CCFL filters out the strong and very destructive UV mercury line at 254 nm, but near visible UV comes through. And I understand that UV LEDs that emit near visible UV (~365 nm) and are packaged in molded plastic will yellow rather quickly.

[Troels]

From the relatively few complaints i've seen regarding dim flexviews, this always involved the LG 15" SXGA+ IPS LCD, rather than the ones from other manufacturers - even mentioned in this otherwise excellent review: http://www.robgalbraith.com/bins/multi_ ... -9320-9876 .

There are many different CCFLs all of different quality, color spectrums and life time. Other TFTs can also dim considerably over time simply due to the CCFL. Not that it's a bad CCFL per se, since it may have other aspects speaking for it such as a generally constant gamut in it's life time, rather than becoming tinted.

I have never seen an LG IPS SXGA+ (that i remember), but the IDTech 15" SXGA+, UXGA and QXGA haven't changed that much during their life. Neither has the Hydis 15" UXGA. The panels by IDtech have lower transmittance and in theory requires a stronger backlight than the Hydis AFFS panels, since these are based on the original IPS matrix structure, where much more of the area is used up by transistors.

See: http://www.beck-oled-lcd-tft-display.de ... _img01.gif (FFS to AFFS+) versus IPS (S-TFT): http://img329.imageshack.us/i/evolution ... 40ko2.jpg/

A "trick" that is used is to degrade how much light is absorbed by the color filters... a bit like dissolving water color in water. The more clear the water is the more light is not absorbed by the colored water, but the color is however pale in comparison to what it appears to be like on your 26" NEC. If you display any primary color on a flexview and compare it to your NEC, the NEC would produce a more solid (correct) representation.

Your NEC is the LCD2690WUXI or WUXI2, right? Those are H-IPS (~IPS-Pro) with a very high transmittance too, and multiple CCFLs, so it's bound to be much better, and the CCFL allows for a higher gamut too.
The IBM T210 was a 20" QXGA LCD using an IDtech IPS panel. The brightness is only rated at 235 cd/m2 but still has a built-in fan. I'm guessing the backlight is very powerful, due to the fact that it has a wider color gamut than their laptop IPS displays.

[sjthinkpader]

High end LCD monitors sometimes use CCFs with two different color temperatures to widen the backlight color spectrum. LCD backlight tends to wash out some colors by the narrow wavelength range of the backlight. Direct emissive displays such as plasma and OLEDs doesn't have this problem.

[kurutta]

My 26" NEC is the LCD2690WUXi2. Works well.

Not sure I understand the advantage of having multiple CCFL. I thought having nearly mono-chromatic red, green and blue light sources was how one got a large color gamut and saturated colors. Perhaps if one had two light sources of different color temperature you could, by changing the relative brightness of these sources adjust the color temperature of the display. Adjusting the color temperature of the back-light relieves the LCD panel from having to do it. This would mean the panel would preserve all of its contrast range for representing the displayed image. Was not this an advantage of LED back-light LCD displays where there are three primary color sources that can be independently adjusted to create various color temperatures. Do I have this right?

[geohsia]

I thought I read earlier that the yellowing was based on the LG vs the other manufacturer. Lenovo sells refurbed T60p's on eBay. Is there a way they can tell what LCD they use besides ripping the whole thing open? I am a photographer and am really thinking about the Frankepad. Do you guys know how well the IPS screens respond to profiling using a calibrator? If the screen yellows can the screen be calibrated to adjust for it?

[kurutta]

Is there a way they can tell what LCD they use besides ripping the whole thing open?

Check out the Hardware Maintenance Manual for the T60 and T60p:

http://download.lenovo.com/ibmdl/pub/pc ... 844_04.pdf

On page 203 of this document you can see that for 15" units with UXGA (1600x1200) IPS panels the only supplier is BOE-Hydis. There are two different part numbers though.

LCD panel, 15-in. UXGA FFS, BOE-Hydis, FRU No: 13N7076
LCD panel, 15-in. UXGA FFS (sRGB), BOE-Hydis, FRU No: 13N7194

I don't know what what the difference is between these panels, or what 'sRGB' refers to?

[goofyGAguy]

According to ThinkWiki, the IDTech UXGA 92P6753 was also used in the T60p.

[kurutta]

Thanks goofyGAguy. I checked ThinkWiki and you are correct that it shows several other UXGA panels used in the T60p.

I've been trying to figure this stuff out by carefully reading the T60/T60p Hardware Maintenance Manuals and by querying the Lenovo site with various Product Numbers. It appears that the hardware manual is not the last word on which components are used.

Also, according to the ThinkWiki display table, only the T60p was supplied with the UXGA (1600x1200) IPS panels. I suppose that this is long been understood by experienced ThinkPad users. Just figuring this out myself.

So, is it true that no T60 had a UXGA panel? Highest resolution is 1400x1050. Right?

[goofyGAguy]

So, is it true that no T60 had a UXGA panel? Highest resolution is 1400x1050. Right?

I believe only the "p" models of the T60 were available with UXGA, unless it's a FrankenPad.

[ajkula66]

goofyGAguy wrote:

I believe only the "p" models of the T60 were available with UXGA, unless it's a FrankenPad.

That is correct. Another fact to bear in mind is that a bunch of the late 15" T60p units were shipped with SXGA+ LCDs instead of UXGA...

[Binh]

In my experience, the type of LCDs in 15" 4:3 T60p is depended on the date of manufacture as follows:
- Before Nov. 2006: only BOE-Hydis AFFS UXGA
- Nov. 2006: BOE-Hydis AFFS UXGA or ID-Tech IPS UXGA
- Dec. 2006: only ID-Tech IPS UXGA (probably Lenovo experienced shortage of BOE-Hydis UXGA and it had to use ID-Tech from old reserve for T4x, most of ID-Tech were actually manufactured in 2004). Most of T60p manufactured in this month were the famous model 2007-WUK.
- After Dec. 2006: only SXGA+ are available (probably Lenovo still experienced shortage of BOE-Hydis UXGA and it decided to switch to SXGA+ resolution).

[sjthinkpader]

BOE-Hydis had a turbulent 10 years being acquired and sold off several times:
http://techon.nikkeibp.co.jp/english/NE ... 27/143106/

The premium for a "p" model cannot compensate the cost in making a low volume display like the IPS UXGA panel.

[geohsia]

So this makes life a little confusing. How do I pick the LCD that will last the longest? I am a photographer and am on the road a lot and budget-wise the Frankenpad is probably my best bet since I already have a T61. Should I pick up a T60p chassis and then just upgrade it to a BOE-Hydis LCD? Not sure where I can even get one of those. I'm concerned about dimming because the whole point of moving is for the screen and if the screen quality is going to fade, I might as well just stick with my T61. Any help would be greatly appreciated. Thanks.

[sjthinkpader]

My 26" NEC is the LCD2690WUXi2. Works well.

Not sure I understand the advantage of having multiple CCFL. I thought having nearly mono-chromatic red, green and blue light sources was how one got a large color gamut and saturated colors. Perhaps if one had two light sources of different color temperature you could, by changing the relative brightness of these sources adjust the color temperature of the display. Adjusting the color temperature of the back-light relieves the LCD panel from having to do it. This would mean the panel would preserve all of its contrast range for representing the displayed image. Was not this an advantage of LED back-light LCD displays where there are three primary color sources that can be independently adjusted to create various color temperatures. Do I have this right?

The human eye has a much wider spectrum sensitivity than most illumination source, other than sun light. The natural color that we judge is by sun light illumination. The gray scale in TFT are by design spaced evenly. The CCFL or LED backlight sources have relatively narrow spectrum with more emission intensity in their center wavelength area. Coherent light source such as lasers are make to extremely narrow spectrum just a few nanometers wide. RGB wavelengths are considered 650nm, 510nm and 475nm respectively. CCF or LED doesn't illuminate 475 to 650nm evenly. So using two types of CCF with different color temperature (center wavelength) helps to spread the intensity over a wider wavelength spectrum.

Color correction software uses TFT grayscale to even out this uneven illumination by backlight sources.

The human eye is more sensitive to wavelength near green. So most graphics controller and system software assign more bits to give green color grayscale more control in brightness, 1 or 2 bits more than red and blue. Most laptop manufacturers spec bright green (stuck) pixels more tightly than red and blue due to this.

Most "white" LEDs do not emit the wide spectrum light that we see. They emit most light around 450nm (blue) then have a yellow phosphorus coating to change the light to white. Over time the phosphorus coating will degrade and light change to blue.

Most "efficient" light sources don't emit wide wavelength spectrum. Tungsten filament emits lots of wavelengths including those we cannot see, such as infrared, hence its inefficiency.

[sjthinkpader]

So this makes life a little confusing. How do I pick the LCD that will last the longest? I am a photographer and am on the road a lot and budget-wise the Frankenpad is probably my best bet since I already have a T61. Should I pick up a T60p chassis and then just upgrade it to a BOE-Hydis LCD? Not sure where I can even get one of those. I'm concerned about dimming because the whole point of moving is for the screen and if the screen quality is going to fade, I might as well just stick with my T61. Any help would be greatly appreciated. Thanks.

15 inch IPS for T60/T60p are available in UXGA and SXGA+. SXGA+ IPS panels are just as nice as UXGA. Just set backlight off timer and they should last a long time. Bear in mind the "screen saver" does nothing for LCDs. The backlight has to be off.

[geohsia]

15 inch IPS for T60/T60p are available in UXGA and SXGA+. SXGA+ IPS panels are just as nice as UXGA. Just set backlight off timer and they should last a long time. Bear in mind the "screen saver" does nothing for LCDs. The backlight has to be off.

I need the extra resolution of the UXGA screen so hopefully they're not any worse. Is the backlight timer setting the same as turning off the display in the power settings? I don't see one specifically for backlight.

[goofyGAguy]

I need the extra resolution of the UXGA screen so hopefully they're not any worse.

I've used ThinkPads with FlexView screens from all three suppliers, and IMHO the Boe-Hydis UXGA is the nicest of the bunch.

[geohsia]

I've used ThinkPads with FlexView screens from all three suppliers, and IMHO the Boe-Hydis UXGA is the nicest of the bunch.

So how do I find out if the one I'm ordering is a Boe-Hydis? Or if I have to order an old one and swap it with a Boe-Hydis, were do I go to order one?

[sjthinkpader]

... Is the backlight timer setting the same as turning off the display in the power settings? I don't see one specifically for backlight.

Yes, display off timer in power manager.

[Worzyl]

So how do I find out if the one I'm ordering is a Boe-Hydis? Or if I have to order an old one and swap it with a Boe-Hydis, were do I go to order one?

If your a photographer and plan on installing a screen, you could always look at the IDTECH IAQX10N QXGA 15", offering a resolution of 2048 x 1536 panels that are also IPS.

[sjthinkpader]

Does the IDTech QXGA even work in T60 without EDID?

[GpsPasSion]

Not sure if the XGA screen of the X61 Tablet is FlexView or IPS but even though it is less than 3 years old it looks dimmer and yellower than the 8 year old screen on my x31!