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Optical Sensor vs Optical Encoder

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quanghoc@gmail.com - 31 Aug 2006 00:06 GMT
Are those two the same thing?
http://www.mouser.com/catalog/627/1256.pdf
Chris - 31 Aug 2006 01:44 GMT
> Are those two the same thing?
> http://www.mouser.com/catalog/627/1256.pdf

http://en.wikipedia.org/wiki/Shaft_encoder
http://en.wikipedia.org/wiki/Optoelectronics
Jonathan Kirwan - 31 Aug 2006 03:17 GMT
>Are those two the same thing?
>http://www.mouser.com/catalog/627/1256.pdf

The first one on the page includes a 1/8" steel shaft.  You might put
a knob on the end of it for a manual control of some kind.  The next
one accepts a keyed shaft, as I gather it.

These are some of the most outrageously expensive units I've seen in
my life, though.  I guess you really pay for the 1024 PPR.  But I'd
consider the idea of learning how to make my own at that price and
then go into a business competing with them.  Sheesh!

Jon
Chris - 31 Aug 2006 03:43 GMT
> >Are those two the same thing?
> >http://www.mouser.com/catalog/627/1256.pdf
[quoted text clipped - 9 lines]
>
> Jon

Hi, Mr. Kirwan.  Sadly, these *are* reasonably priced.  BEI has a
reputation as one of the most reliable industrial optical encoders, and
they always are within specified tolerance.

Thus it has always been.  Precision optics (they photomask the
quadrature pattern onto a glass disk), a small electronics board and a
lot of manual assembly labor.  If you can figure out a way to beat
their price, I'll be standing at the head of the line.

Cheers
Chris
Greg Hansen - 31 Aug 2006 16:31 GMT
>>>Are those two the same thing?
>>>http://www.mouser.com/catalog/627/1256.pdf
[quoted text clipped - 13 lines]
> reputation as one of the most reliable industrial optical encoders, and
> they always are within specified tolerance.

Oh, $200 isn't so bad.  They can get a lot more expensive that that.
I've used one that returned absolute angle with a precision somewhere in
the arcsecond or milliarcsecond regime-- sitting still on a fixed shaft,
it showed constant angle fluctuations from the vibrations in the floor
and the air.  The glass disk reflected rainbow colors, like a CD.  I'm
not the one who bought that one, but I know the price tag was in the
thousands.
Jonathan Kirwan - 31 Aug 2006 19:40 GMT
>>>>Are those two the same thing?
>>>>http://www.mouser.com/catalog/627/1256.pdf
[quoted text clipped - 21 lines]
>not the one who bought that one, but I know the price tag was in the
>thousands.

OMG!  Now there is an idea!  Picking the right CDROM/CD writer combo
and then writing a certain pattern on the disk, using those smaller CD
ROMs that are sometimes used by vendors.  Then the right pickup design
for decoding the pattern into pulses.

Could even purchase the manufacture using custom disk sizes and
pressed patterns.

Hmm.

Jon
Jonathan Kirwan - 31 Aug 2006 19:36 GMT
>> >Are those two the same thing?
>> >http://www.mouser.com/catalog/627/1256.pdf
[quoted text clipped - 13 lines]
>reputation as one of the most reliable industrial optical encoders, and
>they always are within specified tolerance.

I wasn't disparaging them, only noting the cost compared to lower
resolution optical units I _have_ purchased before (32 and 64 counts
per rev) for knobs (at $6 each, btw.)  I've used 1024PPR encoders
before for an infusion pump tester, but someone else actually did the
design and purchase of them, so this was a surprise to me.  I accept
your point that this is reasonable, if too high for anything I'm
likely to care about in hobby work.

It does make me more interested in dismantling them, though.

>Thus it has always been.  Precision optics (they photomask the
>quadrature pattern onto a glass disk), a small electronics board and a
>lot of manual assembly labor.  If you can figure out a way to beat
>their price, I'll be standing at the head of the line.

Hehe.  You are buying these things, too?

I need to look at the complexity of solving the etched/photomasked
issue.  Sounds interesting to think about, anyway.  Thanks for the
info.

Jon
quanghoc@gmail.com - 31 Aug 2006 16:35 GMT
> The first one on the page includes a 1/8" steel shaft.  You might put
> a knob on the end of it for a manual control of some kind.  The next
[quoted text clipped - 4 lines]
> consider the idea of learning how to make my own at that price and
> then go into a business competing with them.  Sheesh!

Then I wonder why Mouser put the Optical Encoder under Sensor category.
Pls check it out in mouser.com
 
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