What I need to know about PWM flicker?

A quick FAQ about the common questions about PWM flicker, because sometimes it may be confusing with all the information out there.

Write me somewhere if your question is not answered and I will answer it and add the answer here πŸ™‚

Do my monitor flicker?

Most of the time yes. This depends on whether your monitor uses PWM or DC dimming.

What is PWM flicker?

Some manufacturers use pulse-width modulation to control the brightness of the monitor.

What is Pulse-width modulation?

Basically turning the LED on the backlight ON and OFF.

Why is this unhealthy?

Your eyes start to contract like this

And you get eye strain and eye pain.

How to fix this?

Set your monitor Hardware brightness toΒ 100%Β using your monitor buttons.

Why set myΒ monitor Hardware brightness to the MAX?

Most monitors don’t use PWM at maximum brightness.

What happens if my brightness is set to 80%?

Your monitor may use PWM

What happens if my brightness is set to 50%?

Your monitor may use PWM

What happens if my brightness is set to 100%?

Your monitor probably is not using PWM and you don’t get this ON and OFF thing and eye strain.

Isn’t 100% brightness unhealthy?

Yes if your room lighting is really low.

Why is this unhealthy?

For best eye protection and least amount of eye strain and eye pain, your monitor should not look a light source in the room.

It should match the brightness of the room and not look like a light source.

100% brightness in dark room is bad?


And with 50% brightness, I may get even more eye pain?

Yes, if your monitor uses PWM.

Then what to do?

Iris can control the brightness of the monitor without using PWM.

I don’t want it, what else?

Turn ON the lights in the room all the time and use your monitor at maximum brightness.

I like a dark room, what else?

You can buy some new monitor which is flicker-free or use Iris.

So I should use Iris at maximum brightness?

No, Iris brightness is healthy and doesn’t use PWM.

You can use whatever value you want with Iris, but your monitor hardware brightness from the buttons is good to be at 100%.

Ideally, match the brightness with Iris to your room lighting.

So I will not get eye pain if Iris is set to 50% brightness?


Will I get eye pain if Iris is set to 40% brightness?


Will I get eye pain if Iris is set to low brightness?

If your room is really bright and your monitor brightness is dark you may get eye pain.

Try to match the room lighting to the brightness of the screen.

If brightness is set to 150% from Iris will I get less flicker?

It will be the same as any other value.

Iris can’t change the hardware but can remove the PWM flicker when controlling the brightness.

When backlight Hz is lower there is more eye strain?

Yes, you have bigger breaks between ON and OFF and your eye contracts more.

When backlight Hz is bigger you getΒ less eye strain?

Yes, you have really small breaks or there are just no breaks in the light and your eyes don’t contract.

What is our goal for Eye health?

Basically, our goal is to have a constant light level which is not possible with LED or the highest possible Hz rate with LED.

Lower Hz rate is like turning the lightbulb in the room ON and OFF all the time.

Is no flicker 0 Hz frequency?

No, we call flicker this ON and OFF.

Basically, in monitors, you strive for the biggest possible Hz for lowest eye strain.

In E-ink, you have 0 Hz frequency but the technology is different.

0 Hz is no flicker but you can’t have this thing with any light source.

You can get 0 Hz from a book or some physical object like a rock.

I’m confused, what to do?

Set your monitor hardware brightness to the MAX from the monitor buttons and use Iris to control the brightness.

Should I quit monitors altogether?

Well, this is the best solution but it is really hard in our world of technology and electronic devices altogether.

Are flicker andΒ EMF connected?

Well, both came from electrically charged objects but there is no big connection.

Do all monitor use PWM?

No, but a lot of them, the other monitors use something called DC dimming.

What is DC dimming?

Instead of using short breaks to control the brightness like this

You change the DC like this

And this doesn’t cause flicker.

So DC dimming doesn’t flicker?

Well, there is subpixel flicker and all kinds of other stuff but it doesn’t use PWM to control the brightness.

DC dimming is better than PWM.

Do Iris does the same as DC dimming?

Yes, but Iris changes the contrast a bit so DC dimming is better.

However, if you don’t want to spend a lot of money for a new monitor and want automation Iris is better.

Anything else?

Try IrisΒ for a couple of days and see if it helps you with eye pain and sleep problems.

If it doesn’t you can always uninstall it with 2 clicks.

Daniel Georgiev
CEO Iris Technologies

Publishing date: 15.05.2018

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