Pulse-Width Modulation, or PWM, is one of the ways display makers can use to adjust the display's brightness. PWM is considered to be an easy (or cost-effective) way to control the brightness, but it has serious drawbacks, such as flicker that may cause eye strain and headaches. In this article we'll discuss PWM and its effects on OLED displays.
PWM basics
PWM is easiest to understand in displays that use backlight, like LCDs. In LCDs that use PWM, the backlight is always on at its fullest brightness. If you want to achieve a lower brightness, you turn the display on and off in a very high frequency. This frequency is not perceived by the human eye, which usually sees anything that flickers faster than about 60Hz (60 times per seconds) as consistent. Some people, however, are much more sensitive to flicker.
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Comments
Hi,
according to Rtings.com the LG Panels don´t use PWM.
best regards,
Rini
10% of the population suffering ill-health because of TV flicker is a stunningly large number of people. Globally this is billions of people. UK wide it is millions.Unfortunately everybody in our house suffers from it so I doubt that it is just 10%.Anyway, thanks for the article.
Unfortunately the article and the links give no help - where is the list of flicker-free TV's?So I am still looking for a PWM-free TV (and not one which blends PWM with something else instead of just properly getting rid of subliminal flicker).
You stated in your article “Some of this flicker, note, can be content related - as some streaming and video services may reduce the screen refresh rate or the frame rate below 60 Hz. Scrolling screen content also introduces additional flicker from the updating.”
what do you mean by this? I don’t think video service can control the display refresh rate unless you have a variable refresh rate display that adjusts to content being displayed. From what I know most tv content is 24fps aland has been that way forever. Even so if the display is sample and hold there shouldn’t be any flicker in between frames. Also what do you mean by scrolling content may introduce flicker? What is scrolling content and to what specific display does it introduce flicker to? Can you please explain?
Don't know about TV's, but for smartphones and laptops you can get good data here as to which ones have little or now PWM and which ones have a lot: https://www.notebookcheck.net/PWM-Ranking-Notebooks-Smartphones-and-Tablets-with-PWM.163979.0.html
But high brightness make it feel uneasy when we look away from the phone and it mostly feels way to bright to use. So should I use it at least brightness. Should I stop using phone at least brightness.
5. People with very high flicker sensitivity may need to switch to LCD displays, which have relatively slow response times that will dampen any flicker.
This sentence shows a gross misunderstanding of the nature of the problem from the author of the article. Slow response times of LCD displays are caused by the fact that the transparency of a subpixel is changed by physical reorientation of a liquid crystal in the filter. The PWM as a brightness control method, however, does not affect the LCD mask, it operates by switching the LED backlight on and off, which actually happens extremely fast (unlike in the older CCFL-backlit models), hence technologies like Lightboost or Turbo240 that use stroboscopic effect to achieve better motion clarity on LCD displays are even possible with LED backlit LCD.
I'm sorry to say I don't find any helpful information on notebookcheck. Com. It turns out that most of them say they're zero pwm when there is in fact pwm.
The pwm rates were not there, but the screen types were. I was wondering which of my devices were LCD, they all are. The device I have for work is LED, which answers a lot of questions for me. The highlighted model name just takes you to the review page.
As someone who lives in an OLED lit house I would want to know about any deleterious affects of a room lit by OLEDs at the half or quarter brightness setting. Of course it's a bit of an esoteric question that pertains to an audience of dozens or fewer.