What the component does
The code pattern is the optical reference for shaft rotation. Its signal format must be compatible with the motor feedback electronics.
Servo Motor Feedback
Measure motor shaft position so that a servo drive can regulate motion and, with the appropriate architecture, establish commutation position.
Where the component works
Disc follows the motor shaft
- Motor body and bearing support
- Shaft-mounted code disc
- Fixed optical reader
The disc is mechanically coupled to the shaft, while the reader stays on the housing.
The drive uses the measured position
- Rotating track
- Reader produces position signals
- Drive regulates motor response
Incremental signals and an index are not automatically a complete absolute startup or commutation reference.
How the system works together
An incremental design usually combines repeated tracks with a reference strategy; absolute coding can support position identification at startup.
What an unsuitable choice changes
Runout, disc tilt and contamination can vary the readout signal over a revolution. Controller performance cannot compensate for every optical reading defect.
Components for this application
Incremental Encoder Discs
Periodic code tracks for angular increments and speed-derived measurements.
Absolute Encoder Discs
Code patterns for servo systems requiring direct position identification.
Optical Encoder Discs
Existing glass disc examples and a starting point for custom track layouts.
Principles and selection details
System context
A shaft-mounted code disc is read optically as the motor rotates. Repeated tracks support motion feedback; an index track establishes a reference. Code or commutation tracks may be included when required by the motor and readhead design. The disc is the passive pattern, while electrical interfaces are supplied by the encoder system.
Selection considerations
Match the optical periods to the readhead and distinguish periods per revolution from pulses or decoded counts. Disc eccentricity, angular pitch error and mounting runout contribute to the feedback error. Confirm speed, mechanical support and operating temperature as part of the assembly design.
Speed feedback comes from movement over time
The controller derives speed from measured motion and time. A stable, readable periodic pattern supports that estimate, but the disc itself does not output an electrical speed signal. Sensor bandwidth, interpolation and the control algorithm also affect the result.
Related applications
Planning your project
A servo-motor encoder disc rotates with the shaft and supplies periodic, index or coded references to its readhead.
The passive disc does not generate an electrical protocol on its own; speed estimation and interfaces belong to the encoder and controller.
Do A/B channels always need separate optical tracks?
It depends on the head. Some read phase-offset areas of one periodic track; others use distinct patterns. Manufacture for the actual sensor layout.