Author Topic: Are there any RGB boards without visible PWM flicker?  (Read 1266 times)

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Offline jasonrohrer

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  • Location: Davis, CA
Are there any RGB boards without visible PWM flicker?
« on: Tue, 10 September 2019, 15:34:09 »
I'm a video game designer/programmer.

I recently showed my game at PAX West 2019.

For my booth, I wanted to get some nice mechanical keyboards with customizable RGB lighting.  The idea was to highlight the keys that were used in the game, and make the other, non-used keys dark, so that visitors to my booth would know which keys to press when trying the game for the first time.

I bought three Ducky One2 RGB keyboards.  I was amazed by the build quality.  But the RGB back-lighting was absolute garbage, with 100 Hz PWM.  This flickers constantly in your peripheral vision or when you turn your head.  Even worse, different parts of the board (vertical sections of keys) have different PWM phases, so the flicker isn't even constant across the board, but really makes a visual jumble in the periphery.  For example, the left half of the space bar flickers out of phase with the right half.

Waving the keyboard in the air produces a visible strobe effect, as captured by a 1/30 sec camera exposure here (where you can see the halves of the spacebar being out of phase---right half has 4 pulses while the left half has 3 pulses in between):

Anyway, I was heartbroken and disappointed.  I had no idea that this would be an issue with a high-quality keyboard.  I ended up turning the RGB off for my booth and installing some colored keycaps to mark the useful keys.  This works, but isn't as flexible as RGB coloring for marking keys.

Now I'm wondering if ANYONE has solved this problem.  We know that PWM of up to 10,000 Hz is visible to about 20% of the population, and various lighting standards orgs recommend at least 3000 Hz to be invisible to most people.  But still, we see low-Hz PWM eveywhere.... even on car tail lights and headlight accents.  Surely you're joking, Mr. Feynman!  But no, real industrial engineers are installing low-Hz PWM flicker in moving objects.  This is also a problem for any lighting that is going to be filmed.

Walking around PAX, I saw lots of RGB stuff on display from Razer, Corsair, Cougar, Asus, etc.  But upon inspection, all of it was flickering.  Some of it up around 1000 Hz, which is better, but still not good enough.

I saw someone else here complaining about bad PWM and "lipstick on a pig"....  is this really the current state of affairs?

Has no one attempted to solve this problem?

I did get word from the RGB integrated-chip supplier for Keyboardio, and they said they upgraded their chips to do 20,000 Hz PWM, particularly for film industry applications.  So that's a good sign (these guys have a patent on RGB LEDs with built-in IC drivers:

I haven't seen a Keyboardio in person, though.  It's also not a great fit for a booth.

Offline Prelim

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  • Location: Portugal
Re: Are there any RGB boards without visible PWM flicker?
« Reply #1 on: Tue, 10 September 2019, 16:12:25 »

once you master the art of touch-typing, you will never see any flickering from your RGB keyboard
GH60 rev.C - lubed Gat blacks 65g | Poker II - lubed vintage blacks 65g | Ducky Shine 3 TKL  - blacks, white led | Dolch PAC ISO - lubed blacks 65g | Raptor K1 G80-1890HUARF | G80-1800HPP - lubed blacks 65g
Floating on Cherry/GMK caps - WoB, Classic Beige, Dolch, Olivetti, Alcatel MMK and Hellgrau ;)

Offline jasonrohrer

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  • Location: Davis, CA
Re: Are there any RGB boards without visible PWM flicker?
« Reply #2 on: Tue, 10 September 2019, 16:59:17 »
This is for a booth, where I will be standing next to the keyboard 8 hours a day.

I.e., the keyboard will be in my peripheral vision all the time.

Also, even if I wanted an RGB for daily use, when touch typing, the keyboard is in my peripheral vision.

I know you were just joking, but....