BenQ migraine

Adjusting BENQ Blur Reduction and DyAc (Dynamic Acceleration) including Blur Busters Strobe Utility. Supports most BenQ/Zowie Z-Series monitors (XL2411, XL2420, XL2720, XL2735, XL2540, XL2546)
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Joined: 11 Sep 2020, 14:20

BenQ migraine

Post by stafil » 11 Sep 2020, 14:39

For years now I have been suffering from random screen sensitivity and was wondering if anyone else has experienced similar symptoms and found the root cause.

The migraine, pressure at the back side of my eyeballs, doesn't start immediately, but only the night after, while I sleep. After I am done looking at the screen for a few hours however, the light in the room feels different. A bit less contrasty I would say.

I first noticed the problem with the iPhone X, after being a long time iPhone user (3G, 4, 5, 6, 7), and the latest problematic screen is my XL2536 that I use for playing CS:GO.

XL2536 is a 1080p, 144Hz TN panel. I have another BENQ for work, EL2870-B, which is a 4k, 60Hz, TN panel, that I can use all day with no problem. I also have an Asus VP249QGR, which is 1080p, 144Hz, IPS panel, that I can again use to play CS:GO for hours with no problem.

So to summarize, problematic screens:
- iPhone X, 11 - OLED, ???
- BenQ XL2536, 1080p, 144Hz, TN

Non problematic:
- BenQ EL2870-B, 4k, 60Hz, TN
- Asus VP249QGR, 1080p, 144Hz, IPS

So what doesn't seem to be triggering the symptoms are: panel type (TN vs IPS), resolution and ppi, refresh rate. I have also tried glasses that block blue light and that didn't help either.

I am now looking for a 240Hz TN monitor, but dread that it will cause headaches and will be wasted money.

Anybody else facing similar problems and have any solution?

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Re: BenQ migraine

Post by RealNC » 11 Sep 2020, 22:59

Check if the iPhone uses PWM and if the XL2536 has blur reduction enabled (DyAc). Those are known to cause the issues you described with some people. PWM uses flicker to control brightness or to prevent OLED burn-in, and DyAc is a blur reduction method that uses flicker to prevent sample-and-hold blur. Flicker makes some people feel very uncomfortable though.

Most monitors today do not use PWM to control brightness. This is sometimes described as "flicker-free". However, if you enable the blur reduction technology of the monitor (like "DyAC", "ELMB" or "ULMB") then it's not flicker-free anymore.
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Re: BenQ migraine

Post by Chief Blur Buster » 16 Sep 2020, 17:19

Many OLED screens automatically use PWM dimming at its dimmer settings (try full brightness + dark sunglasses), other times it is triggering a persons' sensitivity to blue light (try Night Mode), or a color-gamut sensitivity (try one of the colorblind modes, or test reduced-saturation photos temporarily).

Try turning off DyAc on XL2536, it is a strobed mode, or making sure framerate=Hz. Increase your framerate & reduce your stroberate (use a slightly lower Hz) if you prefer to keep strobing enabled, since low-framerate just look as ugly as PWM dimming, strobing only looks really, really good at framerate=stroberate (or when fps is far beyond, ala overkill framerate)

Also, PWM dimming can create motion artifacts that look like this, when framerate mismatches stroberate:


Sometimes some people get eyestrain from this specific kind of artifact, instead of directly from the flicker itself.

Are you sensitive to flicker universally (eyestrain from all flicker), or sensitive to duplicate-image artifacts (no eyestrain from framerate=Hz strobe, eyestrain from PWM dimming)? Different people have different sensitivities here. Sometimes framerate-stroberate matching solves the flicker eyestrain for some people, which is why some people has had no issues with 120fps ULMB or 60fps CRT, but got headaches from PWM dimming.

There are other causes (brightness strain, blue light strain), just giving extra information to make sure you don't leave stones unturned.
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