I don't think any mechanical scheme will come close to a flying spot=20
scanner (crt) in accuracy or speed.
Raster scanning is also self limiting. However, all of the Laser=20
printers I am aware of are raster printers so anything tighter that that=20
is wasted.

On 10/23/2012 6:28 PM, IVP wrote:
> Hi all,
>
> I'm working on a project which involves scanning line drawings into
> memory (a large SRAM). Ideally the images will be laser printed on
> white paper, so the contrast will be good and lines should be sharp.
> But other users may not adhere to recommendations, for a variety
> of reasons, so I'm looking for components or techniques that will
> reasonably cover all eventualities
>
> My aim is to be able to resolve to 0.5mm or better. I've made an
> X-Y bed, 600mm x 600mm (but I may well go bigger), with a
> couple of steppers and threaded rod that has good positional
> resolution, now I need a read head
>
> Some things I hope to try ASAP -
>
> Illuminate from the back with an LED with a opto sensor above the
> paper. This would involve an extra mechanism for the LED to follow
> the read head. No big deal
>
> A reflective or proximity opto, which would bounce IR off the paper
>
> Some lens system to enlarge the detection area
>
> I've used these techniques for other projects but not with resolution
> as the primary goal. Mostly for event detection. I expect I may have
> to restrict a sensor's field of view (eg pinhole mask)
>
> Any other ideas or experiences ? I keep daydreaming about cameras
> but I don't think that's necessary, and I want to use components that
> are cheap and repeatedly available. Even something like an optical
> mouse sensor perhaps. Cheap enough to scavenge from a bought one
> or pick up as broken
>
> TIA
>
> Joe

--=20
John Ferrell W8CCW
=93The greatest lesson in life is to know that even
fools are right sometimes.=94 Winston Churchill (1874-1965)


--=20
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