Questions about LCD flicker

[beil]

Hello.

I have read that IPS monitors (maybe other types as well) can have flickering effect when brightness lowered. Depending on model this can be more or less noticeable.

The questions are:

1. How common is it with IPS monitors? How common is it with monitors with other types of panels?

2. What is typical frequency of flicker? 60 Hz? 85 Hz? 100+ Hz?

 

[sam_p_lay]

I think you're talking about PWM (Pulse Width Modulation) and it's nothing to do with IPS - it's used in all panel types. Frequency varies by monitor. The ASUS PB278Q for example is at 240Hz. It also depends on brightness - if you're set at 100% the PWM won't be active.

EDIT: Just to clarify, when I say "all panel types" I don't mean "all monitors" - lots of models don't use PWM. I just mean it's not something related to IPS specifically.

 

[Munchbot]

I have an IPS monitor (Dell u2713hm) and I don't notice anything, even at the lowest brightness setting. Sorry, I can't say much else.

 

[beil]

I think you're talking about PWM (Pulse Width Modulation) and it's nothing to do with IPS - it's used in all panel types. Frequency varies by monitor. The ASUS PB278Q for example is at 240Hz. It also depends on brightness - if you're set at 100% the PWM won't be active.

EDIT: Just to clarify, when I say "all panel types" I don't mean "all monitors" - lots of models don't use PWM. I just mean it's not something related to IPS specifically.

Yes, I was talking about PWM indeed.

What is typical PWM frequency in inexpensive monitors?

Does PWM frequency goes down when brightness decreased? By how much?

It seems, it is not mentioned in specifications if monitor uses PWM or not - is it possible to determine that? Maybe there is some database with such data?

Some people say they see PWM flicker, personally I can't stand standard TV for it's flicker (50 Hz in my country), but don't notice any flickering at all at 85 Hz CRT monitor, even when looking with peripheral vision (eyes notice flicker more when looking this way). The question is: how people can notice PWM flicker at 240 HZ? Does it goes down even below 85 Hz when brightness decreased, or does it looks differently compared to CRT?

 

[sam_p_lay]

I'm afraid that unless the manufacturer divulges that information (and they rarely if ever do) you'd need special equipment to tell. tftcentral.co.uk has that equipment, so you could check their reviews if your model happens to have been reviewed by them. And I don't think anyone could ever see 240Hz but other models will use lower frequencies. It's not something I'd be too concerned about personally and if you can't get the information on your particular monitor, maybe you could look at a display model in shop?

 

[sam_p_lay]

You might find this useful:

http://www.tftcentral.co.uk/articles/pulse_width_modulation.htm