Optical Encoder Fundamentals

The most popular type of encoder is the optical encoder, which consists of a rotating disk, a light source, and a photodetector (light sensor). The disk, which is mounted on the rotating shaft, has coded patterns of opaque and transparent sectors. As the disk rotates, these patterns interrupt the light emitted onto the photodetector, generating a digital or pulse signal output.

The encoding disk is made from:

• Glass, for high-resolution applications (11 to >16 bits)
• Plastic (Mylar) or metal, for applications requiring more rugged construction (resolution of 8 to 10 bits)

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Glass NOT fragile
The assumed fragility of glass disks is a myth. Glass encoder disks easily withstand the levels of shock that destroy the ball bearings of any motor or other apparatus to which the encoder is mounted. While it is true that glass disks will chip or fracture when abused during installation, metal and mylar film disks are just as easily damaged if handled improperly. The supposed superiority of metal or film disks is a marketing claim, not an engineering fact.
- Jan 12, 2009

Very good, but too shortened
- osama salah, OSAMA. os.dexterity@ymail.com - Dec 9, 2008

That was it?
- Jul 27, 2007

ok.
very very elementary. needs to be further elaborated.
- sid - Jun 18, 2007

thanks
it was useful thanks
- jack, n & n. sasas@sa.com - Apr 24, 2006

Quadrature encoders?
Quadrature encoders are a very common way of sensing rotary or linear motion and direction. Shouldn't it at least be mentioned?
- Brad Mosch, Mosch Electronics. bmosch@cfl.rr.com - Jan 5, 2005

not enough info
This page, although informative lacks some of the more pertanent info. Like what types of output the optical encoder may be purchased with, such as what is NPN open collector, totem pole, line driver outputs and their importance in selecting the proper type of encoder for the application.
- Reza Khoshnoodi, Vigo Importing co.. go_rez75@yahoo.com - Feb 15, 2003

Engineer industrial electronics
Presentation is good.Had it been presented in different colours,with example/application,it would have got better effect to understand. Thanks.
- Ashok Awachar, icl. awachar@yahoomail.com - Feb 18, 2002