3 ms·
Even tough LCDs sample and hold (so, no refresh flicker like a CRT) many employ a PWM to modulate the backlight brightness which will cause it to flicker in exc
by amlib 2y ago
Even tough LCDs sample and hold (so, no refresh flicker like a CRT) many employ a PWM to modulate the backlight brightness which will cause it to flicker in excess of your refresh rate, with the pattern varying according to the set brightness.
Some PWM flicker might reach a frequency that is low enough to bother you, I've read about people who bought a brand new LCD TV and had to return it due to headaches, supposedly attributed to the rate of flicking by the PWM.
Some monitors are sometimes even reviewed as not employing a PWM thus being easier on the eyes.
- Sohcahtoa82 2y agoI don't think I've ever noticed flicker on an LCD screen, even when I first started using LCD some time in the mid '00s. And I definitely notice the flicker in a CRT, especially when I'm not looking straight at it (oddly). Heck, I see the flicker of LED Christmas lights.
- amlib 2y agoYou will never visually see flicker on an LCD unless it's malfunctioning or you have activated black frame insertion. But the flicker is still there on PWM equiped ones, only visible with special equipment or slow motion cameras. The problem them is that your brain might be subconsciously sensitive to some specific flicker patterns, resulting in the aforementioned headaches.
- kanbankaren 2y agoFrom what I have read, the PWM frequency for LCD backlights is in the order of several kHz which is unlikely to be a nuisance.
- amlib 2y agoYes, but some implementations or edge cases (like putting some TVs/monitors in it's max brightness/dynamic mode) can have the PWM frequency drop to as low as 120hz with god knows what duty cycle.