Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!olivea!tardis!tymix!uunet!mcsun!news.funet.fi!cc.tut.fi!mk59200
From: mk59200@cc.tut.fi (Kolkka Markku)
Newsgroups: comp.robotics
Subject: Re: What is the cheapest shaft encoder you know of?
Message-ID: <1991Jun20.094249.27006@cc.tut.fi>
Date: 20 Jun 91 09:42:49 GMT
References: <3755@intvax.UUCP> <6185@ptsfa.PacBell.COM> <1991Jun19.044959.23200@wpi.WPI.EDU>
Organization: Tampere University of Technology, Finland
Lines: 23


In article <1991Jun19.044959.23200@wpi.WPI.EDU> ear@wpi.WPI.EDU (Eric A Rasmussen) writes:
>Excuse me if I am missing some subtle flaw in reasoning, but I think I have
>just come up with a very simple and cheap method of producing the optical disk
>part of an optical encoder.
>
>Steps
>-----
>1) Use a CAD package, drawing program, or whatever to design the simple radial
>lines and circle pattern which will appear on the disk.
>2) Make a good dark printout of said design on a laser printer.
>3) Convert this to a transparency such as used for overhead projectors with
>one of those thermal things often found in the office closet.
>4) Cut the design out of the plastic.

Yes, this should work fine if you don't need very fine resolutions.
If you have access to a Linotronic phototypesetter you could output
the encoder disk directly to film.  If you are a software hacker,
write a PostScript program to output the encoder wheel direcly.
I once made a 8-bit Graycode encoder this way.

--
	Markku Kolkka
	mk59200@cc.tut.fi