Sensitive to onscreen flickering? Take caution when purchasing these Lenovo ThinkPad SKUs
Pulse-width modulation (PWM) is an important but not often discussed property of laptop displays. PWM describes the flickering of the LED backlight that some laptop displays may employ in order to control the brightness of the screen. As our page on PWM details, the constant flickering can cause eyestrain and headaches for users especially if they have to stare at the screen for hours throughout the day.
Unfortunately, PWM is present on a wide array of laptops including some of Lenovo's most popular models. We've tested multiple SKUs of the ThinkPad T480, T480s, x380 Yoga, and P52s and most of them utilize PWM to control the brightness of the display. Whether or not each model exhibits PWM will depend on the native resolution as our table below shows.
What's more notable here is not the fact that PWM is present since it is a common method of brightness control. Instead, it is the fact that we can detect PWM at brightness levels of up to 99 percent on these ThinkPad models whereas most other notebooks normally utilize PWM at much lower brightness levels below 50 percent. This means that using one of the these laptops on a brightness setting other than maximum can potentially cause users to experience eye fatigue.
Thankfully, the majority of users will never notice any flickering from laptop displays during regular use. On the other hand, users who are sensitive to onscreen flickering may want to be wary of which ThinkPad models to buy according to the list below.
|Notebook||Native Resolution||PWM?||Frequency (Hz)|
|Lenovo ThinkPad T480||1920 x 1080||No||--|
|Lenovo ThinkPad T480s||1920 x 1080||Yes, from 0 to 99 percent brightness||990.1|
|Lenovo ThinkPad T480s||2560 x 1440||No||--|
|Lenovo ThinkPad X380 Yoga||1920 x 1080||Yes, from 0 to 99 percent brightness||1000|
|Lenovo ThinkPad T580||3840 x 2160||Yes, from 0 to 99 percent brightness||952.4|
|Lenovo ThinkPad P52s||1920 x 1080||Yes, from 0 to 91 percent brightness||21550|
|Lenovo ThinkPad P52s||3840 x 2160||Yes, from 0 to 99 percent brightness||980.4|