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It seems as Lenovo finally noticed and fixed the low PWM frequency issue

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Puppy
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It seems as Lenovo finally noticed and fixed the low PWM frequency issue

#1 Post by Puppy » Sun Apr 16, 2017 6:28 am

Many of Lenovo past models, especially the most expensive ones with higher resolution displays, used very low PWM frequency around 200 Hz in almost whole brightness levels range to control display backlight brightness. Such low frequency can cause eyestrain or headache. Recent NotebookCheck reviews reveals that Lenovo finally (?) noticed the issue and fixed it:

Lenovo ThinkPad T470s (Core i7, WQHD)
Screen flickering / PWM not detected

Lenovo ThinkPad 13 2017 (Core i7, Full-HD)
The display backlight flickers at 30860 Hz (Likely utilizing PWM) Flickering detected at a brightness setting of 90 % and below.

Lenovo ThinkPad X270 (Core i5, Full HD)
The display backlight flickers at 26040 Hz (Likely utilizing PWM) Flickering detected at a brightness setting of 50 % and below.

Lenovo ThinkPad T570 (Core i5, Full-HD)
The display backlight flickers at 26040 Hz (Likely utilizing PWM) Flickering detected at a brightness setting of 40 % and below.
ThinkPad (1992 - 2012): R51, X31, X220
Huawei MateBook 13

Puppy
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Location: Prague, Czech Republic

Re: It seems as Lenovo finally noticed and fixed the low PWM frequency issue

#2 Post by Puppy » Sun May 14, 2017 3:01 pm

With an exception :(

Lenovo ThinkPad T470s (7300U, FHD)

The display backlight flickers at 219.3 Hz (Likely utilizing PWM) Flickering detected at a brightness setting of 99 % and below.
ThinkPad (1992 - 2012): R51, X31, X220
Huawei MateBook 13

Thinkpad4by3
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Re: It seems as Lenovo finally noticed and fixed the low PWM frequency issue

#3 Post by Thinkpad4by3 » Sun May 14, 2017 9:07 pm

Lenovo solution on the T480 will be little shaded glass slides infront of the led backlight that will be embedded in the lcd to control the level of brightness. Take apart the entire lcd to go from 50% to 40% - David "make your eyes Hz from flicker" hill. Lol. Also, only 10% birghtness will come in the box. Each sold seperately at 40$ each.

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Thinkpad4by3's Law of the Universe.

The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

ac427
Posts: 21
Joined: Wed Jan 22, 2014 10:29 am
Location: London, UK

Re: It seems as Lenovo finally noticed and fixed the low PWM frequency issue

#4 Post by ac427 » Sun Jun 10, 2018 7:07 am

Is there any fix for and is the frequency known for the W530?

terannotterran
Posts: 7
Joined: Sun Feb 16, 2020 9:31 pm
Location: USA

Re: It seems as Lenovo finally noticed and fixed the low PWM frequency issue

#5 Post by terannotterran » Sat Dec 30, 2023 6:00 pm

Is there anything that can be done about this for the X230?

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