What is the principle of absolute encoder? What is the difference between incremental and absolute?

An encoder is a device that compiles and converts a signal (such as a bit stream) or data into a signal form that can be used for communication, transmission and storage.

According to its working principle, it is divided into two categories: incremental and absolute. There are three main differences, as follows:

1.Different principles

The Incremental Encoder converts the displacement into a periodic electric signal, and then converts this electric signal into a counting pulse, and the number of pulses is used to indicate the magnitude of the displacement.

There are many engraved lines on the code disc of the Absolute Encoder to arrange each position on the encoder. Since each position is different, if you want to know the magnitude of the displacement, you only need to know the starting position and the ending position, and you don`t need to keep counting like an incremental encoder.

To describe it as pouring water, an incremental encoder is like finding a cup of unknown size and pour water into it. When it is full, empty the cup once, then pour water, and finally calculate the distance based on the number of times the cup is filled.

An absolute encoder is like finding a taller cup with a scale, pour water into it, and finally calculate the distance based on the start and end scale.

There is a problem. What to do if the cup is full? The solution is to find a larger cup with graduations, pour the water in the small cup into the large cup, and finally add up to calculate the distance. This is a single-turn absolute encoder and a multi-turn absolute encoder.

2. Different memory for power on and off

Incremental encoders have no memory. Power off and restart must return to the reference zero position in order to find the desired position, and restart each time the power is turned on. The most common incremental encoder is the positioning of the printer scanner. Every time the printer is turned on, we can hear a crackling noise. In fact, this is the printer looking for the reference zero point, and it can only work after this.

The absolute encoder has a memory, and the target position can be known without returning to the zero position after power off and restart. This prevents the absolute encoder from being disturbed in the process, and its anti-interference characteristics and data reliability are greatly improved.

3. Different application areas

The presence or absence of breakpoint memory makes incremental encoders and absolute encoders very different in the field of use. Incremental encoders are more suitable for determining speed, distance or direction of motion, while absolute encoders are Features are more and more widely used in the field of industrial control positioning.