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The Scientific Reason We Don't Like LED Bulbs

posted by martyb on Saturday July 29 2017, @06:53AM   
from the need-a-faster-flicker dept.

Phoenix666 writes:

Interesting article at Business Insider on why we don't like LED bulbs:

There's a handy trick for reading station signs that otherwise fly past in a blur as you travel in a high-speed train. Look at one side of the window and then immediately at the other side of the window. When you change your gaze, your eyes will automatically make a rapid jerking movement, known as a saccade. If the direction of the saccade is the same as that of the train, your eyes will freeze the image for a split second, long enough to read the station name if you time things right.

Saccades are very fast movements of the eyes. Their exact speed depends on the size of the movement, but large saccades can move the eyes at the same rate as a high-speed train. The image of the station name becomes visible because it is travelling at the same speed as the eye, and the images before and after the saccade are blurred and so don't interfere with the image of the sign. This shows us that our vision is still working when our eyes move rapidly during saccades.

Scientists used to think we could see no more than about 90 flashes of light a second but now we know it's more like 2,000 because the eyes move so rapidly when we change gaze from one point to another. During the eye movement, the flicker of light creates a pattern that we can see. And this has some surprising consequences for our health thanks to the way some types of lighting can affect us. In particular, it could discourage people from using more energy-saving LED lightbulbs.

Most lighting is electric and powered by an alternating current supply, which makes the bulbs continually dim and then brighten again at a very fast rate. Unlike filament lamps and to a lesser extent fluorescent lamps, LEDs don't just dim but effectively turn on and off completely (unless the current is maintained in some way).

The answer is not to make them less piercing?

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Original Submission

• Re:Camera sensors Re:Camera sensors (Score: 3, Interesting) by zocalo on Saturday July 29 2017, @02:58PM (1 child)

  by zocalo (302) on Saturday July 29 2017, @02:58PM (#546271)

  There's another semi-related issue to this that can cause problems [dpreview.com] for digital cameras under certain conditions, and that's LED signage which tends to work by pulsing a matrix of RGB LEDs at a high rate - typically several kHz - to simulate different hues. Combine that with electronic camera shutters that try to achieve a high frame rate by reading out multiple rows of the array in parallel and you can get some very noticeable interference patterns being cast on subjects that are being lit by the signage when shutter speeds and pulse rate align. It's a pretty niche corner case, but for some sports photographers one that they are likely to run into quite often and with no easily predictable way of determining when since there are no real standards for the signage.

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• Re:Camera sensors (Score: 3, Interesting) by RedBear on Monday July 31 2017, @03:24AM

  by RedBear (1734) on Monday July 31 2017, @03:24AM (#546956)

  By a strange coincidence I just now clicked on a YouTube video of a TEDx talk showing a perfect example of that phenomenon. The giant screen behind the speaker is going nuts in the video. Cascading blank lines and other weirdness. Sharp lines between different sections of the LED array.

  https://www.youtube.com/watch?v=6t6rn1a-t6E [youtube.com]

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  ... Peace out. Got bear stuff to do. 彡ʕ⌐■.■ʔ

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