PWM-collection (flicker)

babel-fisher · 09-25-2014, 11:56 AM

As it's very popular to test TFT-screens for PWM-flicker, it's nearly ignored within ereader-reviews.
So i want to start this thread to ask you about your knowledge. Which readers are PWM-proofed and which reviewers take a look at it?

Some people will say it doesn't matter. That's ok. But users seem to be different in cognition.

Short explanation for beginners:
PWM (pulse width modulation) controlls brightness of the light by turning it on/off very fast. At older screens you can see it looking at screen through a camera. But with newer devices not. PWM frequency can rise over 20 khz. This means your eyes/brains gets 20000 or sometimes more flickers in a second. It is said to cause eye-strain, headage, etc.

Thank's for joining!

babel-fisher · 09-25-2014, 04:00 PM

If i am allowed to link, i will start with a review IN GERMAN from chalid from 'allesebook':
http://allesebook.de/testbericht/ony...im-test-48509/
(if its not allowed please just delete the link)

He finds out that the android-reader Onyx T68 seems to use PWM. He only uses a camera and, as he says, a "simple-setup" with a selfmade soundcard-oscilloscope. I guess PWM of most readers has too high frequency to to be recognized this way, but at least the Onyx seems to use a low one.

babel-fisher · 09-26-2014, 04:54 AM

Here are more information about PWM. It's an article from the monitor-manufacture Eizo.

http://www.eizo.com/global/library/basics/eyestrain/

09-25-2014, 11:56 AM	#1
babel-fisher Junior Member Posts: 3 Karma: 10 Join Date: Sep 2014 Device: none	PWM-collection (flicker) As it's very popular to test TFT-screens for PWM-flicker, it's nearly ignored within ereader-reviews. So i want to start this thread to ask you about your knowledge. Which readers are PWM-proofed and which reviewers take a look at it? Some people will say it doesn't matter. That's ok. But users seem to be different in cognition. Short explanation for beginners: PWM (pulse width modulation) controlls brightness of the light by turning it on/off very fast. At older screens you can see it looking at screen through a camera. But with newer devices not. PWM frequency can rise over 20 khz. This means your eyes/brains gets 20000 or sometimes more flickers in a second. It is said to cause eye-strain, headage, etc. Thank's for joining! Last edited by babel-fisher; 09-26-2014 at 04:49 AM.

09-25-2014, 04:00 PM	#2
babel-fisher Junior Member Posts: 3 Karma: 10 Join Date: Sep 2014 Device: none	If i am allowed to link, i will start with a review IN GERMAN from chalid from 'allesebook': http://allesebook.de/testbericht/ony...im-test-48509/ (if its not allowed please just delete the link) He finds out that the android-reader Onyx T68 seems to use PWM. He only uses a camera and, as he says, a "simple-setup" with a selfmade soundcard-oscilloscope. I guess PWM of most readers has too high frequency to to be recognized this way, but at least the Onyx seems to use a low one. Last edited by babel-fisher; 09-25-2014 at 04:06 PM.

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09-26-2014, 04:54 AM	#3
babel-fisher Junior Member Posts: 3 Karma: 10 Join Date: Sep 2014 Device: none	Here are more information about PWM. It's an article from the monitor-manufacture Eizo. http://www.eizo.com/global/library/basics/eyestrain/