What the component does
Periodic divisions provide incremental information; coded tracks support absolute position identification when paired with the intended reader.
Motion Control & Encoders
Convert shaft or carriage movement into a position reference that a controller can use for feedback.
Where the component works
Patterned scale on the moving assembly
- Drive or rotating assembly
- Code disc coupled to the shaft
- Readhead on the stationary housing
The drawing shows a rotary arrangement. A linear scale uses relative translation instead of rotation.
Position feedback closes the control loop
- Pattern moves past the reader
- Optical readhead and signal output
- Controller compares feedback with demand
The encoder supplies position information; the drive and controller determine how the mechanism responds.
How the system works together
The pattern pitch, illumination and detector geometry must work together. The scale is a passive optical component within the sensing assembly.
What an unsuitable choice changes
An incompatible pitch, mounting offset or optical contrast can produce unstable signals even when the nominal division count is correct.
Components for this application
Incremental Encoder Discs
Periodic tracks for relative angular movement and index referencing.
Absolute Encoder Discs
Explore code families for direct angular-position identification.
Glass Linear Scales
Compare incremental and absolute scales for a linear axis.
Other relevant products and configurations
Optical Encoder Discs
Compare two existing disc design examples before defining a custom rotary pattern.
Gray Code Encoder Discs
Absolute angular code for a readhead designed for this encoding.
Binary Code Encoder Discs
Absolute angular code for a readhead designed for this encoding.
Principles and selection details
System context
An optical encoder reads a patterned disc or scale to convert mechanical movement into position information. A rotary disc measures shaft angle; a linear scale provides a reference along an axis. These components work with an optical readhead and electronics to form the complete feedback system.
Selection considerations
Start with the motion axis and readhead architecture. Incremental patterns provide relative movement and may use an index for homing. Absolute patterns encode position for a compatible decoder. Pattern resolution, installed accuracy and repeatability are separate requirements.
Match the feedback location to the task
A motor encoder reports motor-shaft movement; a scale on the load can observe motion after a transmission. Selecting where to measure is as important as selecting the code. Backlash and compliance between those locations remain system properties.
Related applications
Planning your project
Optical encoder discs and linear scales provide position references for motion-system readheads. Rotary axes use discs; linear axes use scales.
The controller uses the resulting signals for feedback. Match optical mode, pitch, reference marks and mechanical installation to the head.
Why is encoder line count insufficient?
Identical line counts can have different reading radii, pitch, index geometry and head arrangements. Define the optical and mechanical interfaces together.