Hope it's not the case, but...
People with photosensitive epilepsy are affected by lights that have different flash or flicker rates from as low as 3 to as high as 60 per second.
People with photosensitive epilepsy are affected by lights that have different flash or flicker rates from as low as 3 to as high as 60 per second.
> Summary
The specifications for the clock were as follows:
* Millisecond precision, with no perceptible jitter
* Display clearly, without flicker, when filmed at very high framerates (20,000fps or more). The brightness should still automatically adjust, of course, and without the use of PWM
The signals rates mentioned in the article are with respect to how frequently the segments are updated, not the brightness. (With the one exception being the colons being PWM controlled, IIRC).
PWM means Pulse Width Modulation. Controlling a (perceived) light intensity of an LED via PWM means (if we pretend for the sake of simplification that the voltage rise and fall is instantaneous, etc) quickly turning the LED fully on and fully off, varying the duty cycle to achieve the desired perceived brightness. This project avoids the flickering inherent with PWM by not using PWM: the voltage itself is set to some fixed value for a given target brightness.
(If one then wonders why this wouldn’t be the default approach for such things: microcontrollers often provide a built in means for PWM output, but it’s less common to have built in true, non-PWM analog outputs, requiring additional parts (thus more cost, more complexity) to implement variable voltage control).
I have to imagine that, as his 20,000fps-or-whatever example demonstrates, you’d run into exposure challenges at speeds fast enough to capture individual digits on this particular clock
I was just raising a general concern about flicker affecting people with photosensitive epilepsy, but if the multiplexing is indeed at 100 kHz per section, that’s definitely outside the problematic range.