Absolute encoders and incremental encoders are two types of encoders with different code disks. Besides the code disk itself, they also differ in performance after power failure, output code type, interference immunity, and price. Relatively speaking, absolute encoders are more suitable for machine tools with special needs, while incremental encoders are more commonly used in general applications. Let's learn about the differences between absolute encoders and incremental encoders.
I. What are the differences between absolute encoders and incremental encoders?
Encoders can be classified into two types based on the perforation method of the code disk: star encoders and absolute encoders. Both types are encoders, but they differ in many aspects:
1. First, the code disks are different: The code disk of a star-type encoder has a fixed number of gratings on the same circumference. The gratings cut the light to generate a certain number of pulses (the number of gratings on each revolution is the so-called resolution of the encoder); while the absolute encoder has different numbers and intervals of gratings on different circumferences on the same code disk. That is, when the code disk stops at a certain position, the fixed position can be formed by the combination of whether the light passes through each circumference of the code disk, and a fixed number is displayed after passing through the output line.
2. Secondly, absolute encoders and incremental encoders also behave differently after a power outage. Incremental encoders cannot record the current position after a power outage and can only be recorded with the help of devices such as counters; while absolute encoders can record the position themselves, so there is no need to worry about the problem of saving the record after a power outage.
3. In terms of output code system, absolute encoders have multiple output code systems (binary code, decimal BCD code, Gray code), which can be directly provided to display units, PCs and other devices, while incremental encoders cannot be directly provided to display units.
4. Compared with incremental encoders, absolute encoders can almost ignore issues such as speed and interference. As long as the encoder stops at a certain position, it can eventually display the current position regardless of the influence during rotation.
5. In terms of price, absolute encoders are generally much more expensive than incremental encoders of the same brand.
II. Which is better, an absolute encoder or an incremental encoder?
Compared to incremental encoders, absolute encoders have stronger anti-interference characteristics and data reliability. However, this does not necessarily mean that absolute encoders are better. Which is better depends on the application: incremental encoders are more universal and cheaper, so they are used in most cases; absolute encoders are more expensive and have a limited range, so they are generally used in machine tools with special needs.
