The official Philips BDM4065UC thread

hernaldo said:
Just done that, it looks exactly like you'd expect. Black bars top and bottom, image takes up whole horizontal screen, no scaling, pixels are mapped 1:1.
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Think I may be playing games a lot in that 21:9 ratio then :)

Makes it about the equivalent of a 38 inch 21:9 screen :D
 
a few things as i begin testing this screen:

- man is this screen huge!
- at native 3840 x 2160 the resolution is a sensible size on 40" without needing to use OS scaling even, so that's good news
- the panel coating is glossy. not mega reflective like some glass coated screens, but glossy like a lot of LCD TV's
- the screen uses PWM for backlight dimming unfortunately at 240Hz frequency
 
Baddass said:
a few things as i begin testing this screen:

- man is this screen huge!
- at native 3840 x 2160 the resolution is a sensible size on 40" without needing to use OS scaling even, so that's good news
- the panel coating is glossy. not mega reflective like some glass coated screens, but glossy like a lot of LCD TV's
- the screen uses PWM for backlight dimming unfortunately at 240Hz frequency
Click to expand...

The PWM dimming, is that once you go below a certain level of brightness? Or is it for anything less than 100%?

Still not sure if PWM dimming is something that affects me. Am sure I must have had monitors using PWM in past, but am sure I have never been aware of any noticeable flickering.
 
TheBigCheese said:
I'm a bit worried about the mention of PWM as well.

I'm trying to find out if any of my Dell monitors have the same thing as I've never noticed by or been bothered with it before.
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PWM dimming is used for anything below 100% brightness on the Philips BDM4065UC. It's a VERY common method for backlight dimming though and has been around for many years. have a read of this article which explains it a bit more:

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

it's more of an issue on modern LED backlights than on older CCFL backlit screens as that article talks about, and explains. so more people find it problematic on modern screens than they used to. Dell have used PWM on many of their monitors, although quite a few more recent screens are PWM-free. you can see a list of known PWM-free models here:

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

ps, didnt mean to alarm anyone, just reporting the facts and findings as i test them :)
 
Baddass said:
PWM dimming is used for anything below 100% brightness on the Philips BDM4065UC. It's a VERY common method for backlight dimming though and has been around for many years. have a read of this article which explains it a bit more:

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

it's more of an issue on modern LED backlights than on older CCFL backlit screens as that article talks about, and explains. so more people find it problematic on modern screens than they used to. Dell have used PWM on many of their monitors, although quite a few more recent screens are PWM-free. you can see a list of known PWM-free models here:

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

ps, didnt mean to alarm anyone, just reporting the facts and findings as i test them :)
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Thanks!

Out of curiosity, just how bright is thing thing on 100%?
 
Baddass said:
PWM dimming is used for anything below 100% brightness on the Philips BDM4065UC. It's a VERY common method for backlight dimming though and has been around for many years. have a read of this article which explains it a bit more:

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

it's more of an issue on modern LED backlights than on older CCFL backlit screens as that article talks about, and explains. so more people find it problematic on modern screens than they used to. Dell have used PWM on many of their monitors, although quite a few more recent screens are PWM-free. you can see a list of known PWM-free models here:

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

ps, didnt mean to alarm anyone, just reporting the facts and findings as i test them :)
Click to expand...


Thanks very much for your reply, I think half the internet is waiting for your conclusions! :D

Very happy with you reporting the facts, but it did sound a little ominous "unfortunately at 240Hz". Having read a little further though, that sounds quite high, does that mean that it won't be as much of a problem as I may be expecting?

Is it something that could give eye strain if used for long periods? I'm typically staring at a screen for around 15 hours a day (:eek:).

Also, does the glossy panel cause a problem at all? Are there reflections etc., in it or is it not so bad?

Thanks. :)
 
TheBigCheese said:
Very happy with you reporting the facts, but it did sound a little ominous "unfortunately at 240Hz". Having read a little further though, that sounds quite high, does that mean that it won't be as much of a problem as I may be expecting?
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I think that article stated 2000Hz is better for LED backlighting, so if thats the case, then the 240Hz here is low?

Either way, will figure something out. Even if means leaving at 100% brightness and making sure my environment is never too dim when playing to offset that brightness.

Managed to track down one monitor I had that used PWM - the LG DM2780D 3D monitor. I used to game on that in 3D for hours, so maybe I am good to go...
 
One thing that can help with running at 100% brightness is to use something like f.lux, it changes the colour temperature of the display so that whites and other bright colours are less intense. Whilst it's not the same as reducing brightness, I have found that it has a similar sort of relief as reducing brightness.
 
Thanks both for your replies.

Wow, that is low then! :eek:

A colour changing program (similar to Twilight on Android I would imagine) might be an idea. It would be useless when I need colour accuracy when editing photographs but if it can be switched on and off it's a thought, that a pain to have to keep thinking about using.
 
It sounds like the same sort of thing. F.lux has a toggle specifically for colour sensitive work. It's actually intended to be used as a warm filter for after dark viewing in non natural light, I however use it to some degree all say, I'll just turn it off when I'm doing work where I need the colours to be accurate.
 
eyetrip said:
I think that article stated 2000Hz is better for LED backlighting, so if thats the case, then the 240Hz here is low?

Either way, will figure something out. Even if means leaving at 100% brightness and making sure my environment is never too dim when playing to offset that brightness.

Managed to track down one monitor I had that used PWM - the LG DM2780D 3D monitor. I used to game on that in 3D for hours, so maybe I am good to go...
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This is the most important part of the article:

So how fast is PWM cycling backlights on and off? This seems to depend on the backlight type used, with CCFL-based backlights nearly all cycling at 175Hz or 175 times per second. LED backlights have been reported typically running from 180 - 420Hz, with those at the lower end flickering much more visibly. Some have even faster frequencies of >2000Hz so it really can vary. While this might seem too fast to be visible, keep in mind that 175Hz is not much faster than the 100-120Hz flicker observed in lights connected directly to the mains power.

100-120Hz flickering of fluorescent lights has in fact been linked to symptoms such as severe eye strain and headaches in a portion of the population, which is why high-frequency ballast circuits were developed that provide almost continuous output. Using PWM at low frequencies negates the advantages of using these better ballasts in backlights because it turns an almost constant light source back into one that flickers. An additional consideration is that poor quality or defective ballasts in fluorescent backlights can produce audible noise. In many cases this is exacerbated when PWM is introduced since the electronics are now dealing with an additional frequency at which power usage is changing.
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In think in that instance 240Hz does seem to be very low and with such a large screen it's all encompassing...I'm having doubts about it now.

No point in having a massive 4K screen if I can't look at it for the time I need to. :(
 
i don't think you will have problem if you never had problem before as most old LCDs after CRT would used PWM ? i heard about it but never happen to me. ( i wouldn't know my old monitors were PWM if i did not read it online )
 
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