Ask Slashdot: Does LED Backlight PWM Drive You Crazy?

jones_supa writes "I would like to raise some discussion about a hardware issue that has increasingly started to bug me: backlight flicker, from which many LED-backlit monitors suffer. As you might know, the backlight and its dimming is driven by a pulse width modulated square wave, essentially flicking the LEDs on and off rapidly. Back in the CRT days a 100Hz picture was deluxe, due to the long afterglow of the display phosphor. LEDs, however, shut off immediately and my watering eyes and headache tell that we should be using frequencies in multiple kHz there. Unfortunately we too often fall behind that. As one spark of hope, the display review site PRAD has already started to include backlight signal captures to help assessing the problem. However with laptops and various mobile gadgets, finding this kind of information is practically impossible. This issue sort of lingers in the background but likely impacts the well-being of many, and certainly deserves more attention." So do LEDs bother your eyes? I think CRTs gave me headaches far more often than has any form of flat panel display, at least partly because of the whining noise that CRTs emit.

Comments

first world problems

[Anonymous Coward]

Waa my computer is too flickery, someone call the waambulance.

Re:first world problems

[Anonymous Coward]

It may not be real though. Every time a new display technology or variation comes out, a bunch of people spring up claiming it causes them such and such problems. In most cases, little or no scientific evidence ever emerges to back these claims up. It's made worse when those making the claim try to sound like they know what they're talking about, as with the author of this peice; if he is experiencing headaches, and they are associated with his monitor, he's got no actual reason to link that to the frequency of the backlight, that's a pure guess. He says he has watering eyes; I'm not aware of any mechanism by which any effect he's experiencing due to his monitor could cause that, that's far more likely to be associated with chemical or allergic reactions, or infection. Yet he states these things as facts. Just like the people that believe wifi signals cause them migraines (although in a blind test the effect never materialises), I'm sure he honestly believes what he's saying, but that doesn't mean it's true, and until there's some proper peer-reviewed medical research done to back up these claims, they should be taken with a grain of salt.