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14422 Views 40 Replies Latest reply: Feb 2, 2009 10:37 PM by Peter Jason
Currently Being ModeratedOct 27, 2008 4:39 PM (in response to YuriNiyazov)Very interesting, considering that illuminated pixels on LCD displays decay slowly, which makes most of them unsuitable for fast paced video games. I run my CRT's at 100hz to avoid flicker, but flicker shouldn't ever be present in LCD screens I'll be VERY interested if you find the source of your problem with that screen of yours. Keep us posted if you get some useful info on your issue.Windows Vista, Windows XP-SP3 - Ipod 4G, Ipod Mini, Shuffle 2G, Nano 2G, Touch 2G
Currently Being ModeratedOct 27, 2008 5:29 PM (in response to YuriNiyazov)You are not experiencing anything out of the ordinary. LED technology is basically the same - just in computer screens it is much smaller. Notice how the big 18 wheelers and state troopers have the new LED warning lights? Notice how much brighter they are? And the closer you get, the harder it is on your eyes. When you get almost next to the lights it practically blinds you. That's because LED technology operates on a different wave length than an incandescent bulb which simply uses voltage and wire to produce light. LED's use a dome lens to amplify the light. Without getting too involved here in the physics of LED's, suffice it to say that the "old" school computer screens that used a matte finish in front of a fluorescent bulb was considerably more palatable to the eyes. As you are now finding out.
Which is better? Let your eyes be the final judge.
Currently Being ModeratedOct 27, 2008 9:05 PM (in response to baypharm)Thank you very much for answering.
If you don't mind, let's actually get into the physics of LEDs. Because maybe this will enable me to find a solution to this problem. If this is an issue with the LED backlight, then this will be a huge problem for me because I noticed that many other manufacturers are also switching their backlights from CCFL to LED - and this means that I won't be able to work on any of the new laptops; what's worse, I am sure that this trend applies to regular LCD monitors as well (although I don't really keep up with that industry anymore since I've gone laptop-only) and that means that I will not be able to own desktop LCDs either; and I am not sure what other options I have.
I am not a physicist, so a lot of this is probably half-right, derived from what I've picked up just reading other people's semi-informed posts and Wikipedia articles:
LED backlights use PWM (pulse width modulation) to control the brightness of the screen. LEDs are basically either on or off, and do not have a "dimming" control - less current does not result in a less bright light. So, in order to control the brightness of the screen, they cycle the LED on and off many times a second, and the effect is that we perceive it as less bright. Or at least, this is what this guy writes:
The solution that he discovered is to crank up the brightness all the way so that the flicker that he sees is no longer perceptible.
I have a bunch of technical questions about his solution, but that discussion seems to have gone dead, so I will post it here.
The first question that I have is this: is flicker really the problem? I've always had issues with CRTs at 60HZ, but usually cranking them up to 75HZ made the problem go away.
Let's look at the specifications at this LED backlight controller:
I am going into some big assumptions here - for example, it is not clear that this is the controller that Apple uses in the new MacBooks, and if it's not, I am assuming that all LED backlights are made equal as far as PWM is concerned - this is not the sort of technical knowledge that I can come across on my own just Googling around. However - the minimum frequency that the controller supports is 100 HZ, which is considerably higher than the 60 HZ that caused problems on old CRTs.
So, maybe it is not the flicker, and your response suggests that it's not, and that it's just the frequency of the color of the LED itself. So, any ideas?2.0ghz MacBook (Late 2008), Mac OS X (10.5.5)
Currently Being ModeratedOct 28, 2008 12:55 PM (in response to YuriNiyazov)I would like to add some points to hopefully further help in understanding. The LEDs used in notebook screen backlights are white LEDs. But LEDs by nature are monochromatic devices and they cannot make white light, which is all colors of light mixed together. The way such LEDs work is that they make invisible, ultraviolet light and there is a phosphor coating within the LED structure that the UV light excites and the phosphor is what emits white light. This is not altogether unlike an old monochrome CRT in the way those devices made white light.
The presence or absence of detectable flicker in the backlight will have nothing to do with the refresh rate of the LCD panel, so trying to alter that would lead to a dead end as far as a solution goes IMO. But as that fellow RMartin111 points out in the thread you linked to, when you set the brightness to full, the backlight is on steady and there is no more pulsing of the backlight so the flicker will be gone. RMartin111 then used sunglasses to lower the brightness. Obviously not an ideal solution.
Older notebook computers also use PWM (pulse width modulation) to reduce the brightness of the CCFLs (cold cathode fluorescent lamps) in their backlights. And they also use phosphors to make white light. It's a bit of a puzzle why flicker would be more perceptible in the new crop of LED backlit screens versus the older CCFL ones for those who are sensitive to this. Obviously this will have to bear further study by Apple and the industry at large.
I agree the prospects for future computer screen use may seem gloomy for you since the whole industry, including for monitors, will be undergoing a conversion to LED backlights. But looking at the spec for that Freescale MC34844 you referenced in the second link, it says the PWM controller's minimum frequency of operation is 100 Hz, but the maximum is a whopping 20kHz, which is way beyond where any human would be able to perceive flicker. Furthermore, it says that the PWM frequency is programmable, which at least suggests the possibility of a firmware or software update, assuming such type of controller is similar to the one used by Apple. So you can be hopeful for something like that.
If this is even a problem for 1% of the population, meaning 1% of all users are susceptible to perceiving the flicker, or receiving some sensation from it, however they might describe it, then that will be a big enough problem that the industry will address it, and the long term prospects of better displays are, in that case, quite good. So I wouldn't worry that you are going to be completely left out from ever being able to use a computer screen comfortably ever again. But I am sorry to hear it is a problem for you with the computer you own today. Good luck.
Currently Being ModeratedOct 28, 2008 1:06 PM (in response to BSteely)So, I went to see "The Genius Bar" people today, and I gotta tell you - naming those guys "geniuses" is an affront to the real geniuses out there.
The only thing those guys suggested is that I get an anti-glare screen. I ordered one to be delivered overnight; considering that the issue is present both at lowest and highest brightness settings, I am not too optimistic that it will solve anything.
Anyway; thank you for the clarification and the well-wishing. I am not entirely sure how to draw industry's attention to this problem; in fact, so far I am having difficulty getting someone at Apple to even acknowledge that this could potentially be a problem and not just me "not being used to the screen".2.0ghz MacBook (Late 2008), Mac OS X (10.5.5)
Currently Being ModeratedOct 28, 2008 3:07 PM (in response to YuriNiyazov)In all seriousness, the only way to get their attention is to return the product. If everyone returns merchandise that is subpar, the mfgr will update the product at some point, or face extinction. If everyone merely "takes it on the chin" when they get shoddy goods, then there is no incentive for a manufacturer to do better. IMO, it's up to consumers to wield their collective power to push for better products. It's YOUR money that you traded for their product. Was it worth the trade?Windows Vista, Windows XP-SP3 - Ipod 4G, Ipod Mini 2G, Shuffle 2G, Nano 2G, Touch 2G
Currently Being ModeratedOct 28, 2008 10:30 PM (in response to YuriNiyazov)I have experienced the same problems. Right out of the box the screen seemed blurry. I can't really put my finger on it, but it seriously strains my eyes. My wife is using the new MacBook Pro and when she saw my screen she instantly said, "wow thats wierd." My previous computer a MacBook air also had an LED display and I loved the display I had no problems at all with it. But I can barely use my MacBook because of the display. This in my opinion is not an LED problem. I'm gonna take it to the apple store and see what they will do.macbook (aluminum), Mac OS X (10.5.5)
Currently Being ModeratedOct 28, 2008 10:55 PM (in response to Alan H.)Alan, it would be great if you could detail your experience with the Customer Service people regarding this problem here. The guy who I talked to refused to even acknowledge that anything could be wrong with the display and immediately said that the problem was "environmental" in nature.2.0ghz MacBook (Late 2008), Mac OS X (10.5.5)
Currently Being ModeratedOct 29, 2008 3:51 AM (in response to Alan H.)This is something that I experienced with my alum Macbook 2.4ghz too, before I returned it - there was definitely something wrong with the screen. It emitted a strange blueish hue that made it very uncomfortable to look at. There was also notable blurring too.
Right before I returned it, I noticed that from an acute angle, looking at the from the right hand side, looking across to the left, that some if the backlighting was clearly visible. It appeared as though the LCD panel was not properly fitted on the left hand side and that some of this light was spilling across the front of the panel, probably causing the uncomfortable light issue. This was not something I have seen before, and was not apparent on a 2.0ghz alum Macbook in the store. Some people have had no trouble with their displays on the new MBs (although the alum Macbook apparently uses an inferior quality LCD panel than the new MBO). It is also apparently a different quality panel to the very good one used in the MBA - I had hoped that they would have been the same.
I now have a new MBP with no such problems. Its viewing angles are also noticeably better. It is of course a large and heavy machine, and not what I wanted. I can't say I'm very happy about it all.UnibMBP, MBA, Mac OS X (10.5.5), iPhone 3G
Currently Being ModeratedOct 29, 2008 8:57 AM (in response to YuriNiyazov)YuriNiyazov, are you sure you still experience this issue at full brightness of the screen? That is not consistent with the issue RMartin111 reports having to do with a pulsing backlight and saccadic eye movement. The backlight ceases to pulse when set to full on. If you still experience the same sensations at full brightness on your MB, then I have no idea what it is that you are sensing.
Currently Being ModeratedOct 29, 2008 1:50 PM (in response to BSteely)I am no no longer convinced that the cause of my issue is the flickering of the LED backlight. I do not see 'flicker', even at the lowest brightness; I just have a weird sensation of my eyes burning. Perhaps it's an issue with the brightness; I think the laptop is too bright even at its lowest setting. I am coming to this laptop from the IBM X31, where the lowest brightness setting is very dark but is still very contrasty so it is legible, and I am used to that screen.2.0ghz MacBook (Late 2008), Mac OS X (10.5.5)
Currently Being ModeratedOct 30, 2008 12:19 AM (in response to YuriNiyazov)YuriNiyazov, I live about two hours away from the nearest apple store, but I should be going this weekend to get them to look at it. So I'll give an update this weekend. I'm hoping I just have an "extra bad" display and that a sympathetic genius will help me out.MacBook (aluminum 2.4), Mac OS X (10.5.5)
Currently Being ModeratedOct 30, 2008 3:12 PM (in response to YuriNiyazov)Update: I bought an anti-glare screen from PowerSupport. I _do not_ recommend this product.
1) it is overpriced. $30 for a piece of plastic with one side sticky?
2) it is very difficult to put on. It immediately begins to attract dust and other types of stuff that's in the air no matter how quickly you put it on the display.
3) It doesn't fix my problem with the eye strain.2.0ghz MacBook (Late 2008), Mac OS X (10.5.5)
Currently Being ModeratedNov 2, 2008 8:14 PM (in response to Alan H.)Hey Alan H. Do you have any news, good or bad, about this issue?2.0ghz MacBook (Late 2008), Mac OS X (10.5.5)