Motion Control Resources
Advantages of Linear Encoders over Rotary Encoders
Lika Electronic USA Posted 05/24/2019
In a large number of applications, linear encoders with magnetic sensing technology can be an excellent replacement for rotary encoders. Thanks to their mechanical and electrical features, they offer several advantages, even in the most advanced automation systems.
What are their main benefits?
They adopt the magnetic sensing technology, so they work without contact and ensure virtually wear-free and maintenance-free operation. There are no moving parts and all the mechanical components found in rotary encoders (flange, shaft, bearings, etc.) are not need, which eliminates mechanical failures . The limited use of both mechanical parts and miniaturized circuits minimizes the overall footprint of the devices. Furthermore, magnetic technology is highly immune to external interferences such as light, oil, grease, water, chemical contaminants, etc. Additionally, magnetic technology enables easy adoption of PCB protection methods such as encapsulating, tropicalization, conformal coating, varnishing, etc. In this way they can achieve the highest protection rates (IP67 to IP69K) and reliably operate in the harshest industrial environments.
Linear encoders have a modular structure; they basically consist of a readhead and a magnetic tape that are not in contact, so the risk of failures due to vibrations, shocks or mechanical stresses is limited.
The range of linear encoders from Lika Electronic has grown more and more and includes today a wide variety of both incremental and absolute devices. Furthermore, it is enriched with solutions that are dedicated to specific applications such as lateral reading sensors, sensors for toothed wheels and racks, sensors for UHV installations, etc. Among the most widely used models from Lika are SME53 and SME54 incremental linear encoders and SMA2 absolute linear encoder.
SME53 is the incremental linear encoder with very high resolution down to 0.08 μm designed for demanding motion control applications.
SME54 incremental linear encoder offers engineers a fully programmable solution, its resolution can be set in the range of 1.25 mm – 0.08 μm along with Index mark duration and counting direction. It provides complete adaptability, versatility and freedom for any type of industrial application. Thanks to their rugged frame and encapsulated electronics, they are optimally protected against dust, oils, liquids, contaminants, shocks and vibrations (IP67 protection). The large permissible tolerances and air gap (up to 2 mm) ease installation and enable minimum installation time. They generate quadrature signals with inverted and Index signals via Push-Pull (HTL) and Line Driver (TTL) output circuits and offer diagnostic LEDs as a standard.
SMA2 is ideally suited for position and speed feedback applications where small size, finest resolution and greatest accuracy are mandatory. It provides high resolution down to 1 μm and high accuracy of ±2 μm. The maximum measuring length is 8.1 m (26.57 ft) and the maximum speed is 10 m/s. It is paired with MTA2 double track magnetic tape, so it is able to deliver both the absolute information for position feedback through the BiSS-C and SSI interfaces and the incremental information for speed feedback through the NPN output circuit. SMA2 is outstanding also in its mechanical characteristics: although the sensing head is very compact and slim, it preserves its toughness. The fully encapsulated electronics is optimally protected against dust, oil, grease, water, shocks, vibrations. Typical applications are for example linear motors, pick & place robots, electronic assembly systems.