Overscan on digital TVs... why?

[George99]

Hello,

I've noticed that many of the digital HDTVs I've seen have overscan. That is, all of the transmitted picture is not displayed on screen.  On my set (a Flat Panel Display) it is a very small amount... less than 1/2%, but why should there be any at all?  Since we're dealing with a digital matrix of exact dimensions and pixel placement, I don't understand why they design in the overscan.
 
I'm not really bothered by this with my set as the overscan is very small, just curious as to why it exists at all.  Anyone know why this happens or can or help me understand this.

George

[StarvingForHDTV]

Good question.  I hope somebody knows the answer.

[Bebop]

Because, manufacturers don't think it is that important for them to adjust it. Besides most of the people in the forum, how many know what "over scan" is?


Actually, over scan is used to mask imperfection inherent in CRTs. If you ever try to fit your your desktop perfectly on your computer monitor. You'll will see pin cushions and geometry distortions on all four sides. IF you over scan the picture the imperfections are less noticeable. It's like putting moldings around your house's windows to make them look good.