Display dimming with PWM?

[blue42]

Hi all

I wonder wether or not t530/430 use PWM in display dimming? And if so, what frequencies?

(It's easy to verify, using a cam and a "test" image... a thin white line on black ground -> http://www.flatpanelshd.com/focus.ph...&id=1362457985
Then "How to test for PWM yourself" -> "The more accurate method:")

Cheers
Chris

Edit:
Meanwhile I own a T430, and yes, it uses PWM dimming, at 220 Hz. Oh well... Lenovo just doesn't care.