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Subject: Re: [Homebrew_PCBs] etched 5/5 results

From: DJ Delorie <dj@...>
Date: 2008-07-04

"Bertho Boman" <boman01@...> writes:
> Your system is getting better and better!

Thanks!

> I am curious though why the comb pattern is only on one side. Did
> you figure out why?

It seems to be related to paper feed through the printer. I mean,
moving a sheet of paper with 1/2880" accuracy isn't easy. The weaving
algorithms, which are designed to hide these inaccuracies, means that
half the dots are printed with the top jets on the printer, and later
the other half are printed with the bottom jets. Even accumulated
error in paper motion is enough to cause the later passes to be off.
If, for example, 1/4 of the pixels are drawn after the paper is "off",
you'll see those ink drops on the clear background, but it's far less
likely to see a clear spot in a dark background - drop overlap hides
the missing pixels.

The comb doesn't happen in the other orientation because the print
head can be positioned more accurately (and repeatedly) than the paper
can.