Wow, there are more LED haters here than I realized...
LEDs are pulsed - they blink on and off rapidly, which may be part of the issue people have with them. Incandescent bulbs do this, too - it's a function of alternating current, which changes polarity in the US 60 times per second (passing through a zero-current moment each time). The …
Wow, there are more LED haters here than I realized...
LEDs are pulsed - they blink on and off rapidly, which may be part of the issue people have with them. Incandescent bulbs do this, too - it's a function of alternating current, which changes polarity in the US 60 times per second (passing through a zero-current moment each time). The difference is, on a filament bulb, the filament doesn't go all the way out at that zero-current moment, because it's still hot from the max-current moment 1/120th of a second before. It dips in brightness a little, but it happens so fast that we don't notice it.
Aside from the blue of the 6500K LED bulbs (vs. the 2700K "warm" bulbs that mimic incandescent bulbs), it could be the much-more-defined pulsing of the LED bulbs that people find annoying and even unhealthy. If you look at an LED and swipe your head to the side really quickly, under certain conditions you can see a "trail of dots" in your persistence of vision, as opposed to the "smear" you'll see under the same conditions with incandescent.
LEDs blink, by the way, because at the energy level they produce their brightest light, they would burn out almost instantly if they were held at that level constantly. The blink allows them to cool off during their off state, keeping them from burning out. Dimmers that work with LEDs vary the ratio between on time and off time - when off for longer than on, the LEDs appear as less-bright.
There's your physics lesson for today, folks. Yes, I know - I'm a geek.
BTW, fluorescent lights make me sleepy, for some reason. I had to fight to stay awake in school a lot of the time, because of those darned fluorescent tubes across the ceilings...
I’ve noticed lately that after reading text on a screen, when I look away, I see stripes, like lines of blurred text that remain in my vision for a while burned into my retinas after I look away from the screen. Do you know what’s going on there?
Persistence of vision. It's your vision system's natural response to staring at high-contrast images.
You can try lowering the brightness on your screen to reduce eye fatigue. As a matter of fact, I just did this on my monitor as I was replying - I often walk away from the screen with tears in my eyes from eyestrain. Thanks for the reminder!
Wow, there are more LED haters here than I realized...
LEDs are pulsed - they blink on and off rapidly, which may be part of the issue people have with them. Incandescent bulbs do this, too - it's a function of alternating current, which changes polarity in the US 60 times per second (passing through a zero-current moment each time). The difference is, on a filament bulb, the filament doesn't go all the way out at that zero-current moment, because it's still hot from the max-current moment 1/120th of a second before. It dips in brightness a little, but it happens so fast that we don't notice it.
Aside from the blue of the 6500K LED bulbs (vs. the 2700K "warm" bulbs that mimic incandescent bulbs), it could be the much-more-defined pulsing of the LED bulbs that people find annoying and even unhealthy. If you look at an LED and swipe your head to the side really quickly, under certain conditions you can see a "trail of dots" in your persistence of vision, as opposed to the "smear" you'll see under the same conditions with incandescent.
LEDs blink, by the way, because at the energy level they produce their brightest light, they would burn out almost instantly if they were held at that level constantly. The blink allows them to cool off during their off state, keeping them from burning out. Dimmers that work with LEDs vary the ratio between on time and off time - when off for longer than on, the LEDs appear as less-bright.
There's your physics lesson for today, folks. Yes, I know - I'm a geek.
BTW, fluorescent lights make me sleepy, for some reason. I had to fight to stay awake in school a lot of the time, because of those darned fluorescent tubes across the ceilings...
Doug, succinctly put.
Thanks for the physics and EE lesson.
Another option for LED screens--app removes blue light screen output on a schedule you set: https://justgetflux.com/
I’ve noticed lately that after reading text on a screen, when I look away, I see stripes, like lines of blurred text that remain in my vision for a while burned into my retinas after I look away from the screen. Do you know what’s going on there?
Persistence of vision. It's your vision system's natural response to staring at high-contrast images.
You can try lowering the brightness on your screen to reduce eye fatigue. As a matter of fact, I just did this on my monitor as I was replying - I often walk away from the screen with tears in my eyes from eyestrain. Thanks for the reminder!