Complete Guide to Incremental Encoders: How They Work and Where They Are Used

Incremental encoders are key components in many industrial systems for measuring motion, monitoring position, and regulating the speed of rotating equipment. They operate by producing a sequence of electrical pulses that correspond to the rotational or linear movement of a shaft or axis. By counting and processing these pulses, control systems can determine how fast something is moving and how far it has travelled, which makes incremental encoders indispensable in automation and motor-control applications.

What Is an Incremental Encoder?

An incremental encoder is a motion and position sensor that outputs signals only when movement occurs. In contrast to absolute encoders, which assign a unique digital value to every position, incremental encoders emit a continuous, repetitive pulse train as the object moves. Each pulse represents a defined step of motion, so the encoder reports changes in position or speed relative to a reference point rather than an absolute coordinate.

Operating Principle of Incremental Encoders

Most incremental encoders are built around a rotating disk, a light source, and a light sensor. The disk carries a series of evenly spaced slots or markings along its circumference. As the shaft turns, the disk rotates between an LED and a photodetector. When a slot passes between them, light reaches the detector; when a solid section blocks the beam, it does not. This alternating light–dark pattern is translated into electrical pulses. An external controller counts these pulses and, knowing the number of slots on the disk, calculates speed and displacement. A higher number of slots provides finer resolution and more precise measurement.

Typical Applications of Incremental Encoders

Because they offer reliable, real-time motion feedback, incremental encoders are used across a broad range of sectors that demand accurate motion control, including:

Factory automation: They support accurate positioning and synchronisation in assembly lines, robotic systems, and conveyor equipment.

Motor control: They help regulate the speed and rotational position of motors used in machinery, electric drives, and renewable-energy systems such as wind turbines.

Industrial machinery: They are integrated into CNC machines, lathes, milling machines, and similar equipment to track spindle rotation and guide tool motion.

Medical and precision devices: In imaging systems and medical robots, incremental encoders contribute to highly controlled, precise movements.

Advantages of Incremental Encoders

Several characteristics make incremental encoders a preferred choice in many designs:

They are generally more economical than absolute encoders, which is attractive for applications where relative positioning is sufficient and position memory is not required. Despite this, they can still deliver high resolution and good accuracy, enabling fine speed regulation and precise positioning.

They interface well with many standard industrial drives, controllers, and PLCs, which simplifies integration into existing installations. Many models are engineered for demanding environments, with robust housings and protection against dust, moisture, and vibration. Because they provide immediate, continuous pulse feedback during motion, they are well suited to dynamic processes that require rapid response and tight control loops.

Incremental Encoders versus Absolute Encoders

Both incremental and absolute encoders are used to measure position and speed, but they do so in different ways and serve different needs. Incremental encoders are typically selected when relative position information is adequate and cost, simplicity, and fast response are priorities. Absolute encoders, by contrast, output a unique digital code for each physical position on the disk. This means that the system always knows the exact position, even after a power interruption or restart, making absolute encoders preferable in applications where position must be retained at all times and recovery after power loss is critical.