Re: [CAD_CAM_EDM_DRO] Linear Encoders

Ian Wright wrote:

> I was playing about with some grids printed on transparent film the
> other
> day and this got me to wondering (which, in turn, made me have to lie
> down
> to recover!). If we have a grid of, say, 10 lines to the inch and
> overlay it
> with a tilted moving grid of eleven lines to the inch, is there a
> vernier
> effect?

Yes, absolutely! But, the beauty of quadrature is that you only need 2
sensors. With
a vernier, you need to 'read' it, ie. scan along for the coincidence
between the lines.
One way it could work is if the grating had thin lines in an otherwise
transparent pattern,
and the analyzer had thin slits in an otherwise opaque pattern. You
would get light
shining through 9 of 10 places on the analyzer, and the one that wasn't
showing light
was the indication of the position reading. So, you'd need 10
photocells.

Jon