In article ,
says...

You're confusing DLP with liquid crystal.

Check out
http://www.hardwareanalysis.com/content/article/1645.7/

Notice the specific reference to screen door effects.

DLP is rapidly becoming the technology of choice among all the
projection makers. LCoS may be an option. Analog? History.

Not all LCD's have this problem. My sony grand wega does not exhibit
this behavior.
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Alex