What Do I Need to Know About Flat Screen Refresh Rates?

A flat screen’s refresh rate is important to you because it reflects how often the picture is “drawn” on the screen every second.  Plasma displays refresh the screen at 60 times per second or 60 Hz.  LCD’s use a different method for refreshing the screen.  Consequently, may people can detect blur on LCD’s that refresh at 60 Hz.  Plasma displays don’t suffer from this.  LCD manufacturers, attempting to compensate for this shortfall, have engineered a technology into their sets called MEMC or “motion estimation-motion compensation”.  This technology actually creates another frame and displays it between existing content frames.  The industry creates confusion by calling MEMC 120 Hz technology because it is not actually refreshing the screen at 120 Hz. 

Further confusing the matter is the introduction of 240 Hz technology.  Samsung and Sony use MEMC again to double the frames displayed on the screen.  Interestingly, with Sony and Samsung 240 Hz LCD’s 75% of the frames that you see are actually mathematical interpretations of the actual content.  Other manufacturers such as Vizio, LG and Toshba blink the backlight rapidly to create what they are careful to call a 240 Hz “effect”. 

At this point, IRM does not recommend purchasing Vizio, LG or Toshiba 240 Hz LCD’s.  The MEMC technology does have a positive effect on perceived motion blur compensating somewhat for the shortfall of LCD vs. plasma displays. 

An excellent article which elaborates on these facts is found here.

Another article which talks about the details of human visual perception can be found here.