Re: plastic strips for encoders

On Sun, 6 Jun 1999 12:27:54 -0400, "Mark Ehle" <mehle@...> wrote:

>I have been in contact with them, too, about a 250 line/inch scale and they
>said no dice. Does anybody know why not? Sure seems to me that this would be
>a better unit than 200 or 360!

It's really quite simple. I chased this waskelwy wabbit down a few
months back, meself, so hopefully I know of what I speak.

The SENSORs that US Digital relies on, namely those made by HP, are NOT
made in a resolution that will accomodate 250 lines/inch, at present. NO
bloody reason by HP couldn't make some at that res, but they don't, and
although I DID talk to the Product Marketing Mgr. of this sensor line,
for some reason I couldn't seem to convince him that us hobbyists should
be considered in their overall product scheme. B)

Bottom line is that the quadrature sensors with their arrays of leds &
sensors, are NOT made by HP at the moment in such a resolution to allow
US Digital to make the films/gratings work, and make us all happy. You
CAN use gratings of slightly varying resolutions from the nominals that
the sensors are rated at, but apparently 250 *IS* too far off from 200
to just whip out a 250lpi grate, and get it to work properly with a
200lpi sensor from HP. Sad, but apparently we're toast on that hope.

Gar