Wednesday, April 25, 2018
Publication Date: 05/1/2007
Archive >  May 2007 Issue >  New Products > 

Non-Contact Magnetic Encoders from Renishaw
Magnetic encoder.
Hoffman Estates, IL — The Renishaw RM22 encoder is designed for trouble-free performance in the harshest environments. The RM22 is designed and manufactured by the company's Slovenia-based partner company, RLS d.o.o. for high reliability in demanding applications and extreme environments.

Non-contact designs — basically a magnet and a sensing chip — the robust, solid-state encoders use a small actuator magnet that fits on the end of a shaft, while the Hall sensor ASIC chip is epoxy-embedded and encapsulated inside a metal housing/mount. Fully sealed to IP68, the encapsulated design provides superior resistance to shock, vibration and acc/dec forces.

While maximum operating temperature is specified as +125°C, the RM22 encoder still survives the very high temperature inside the clutch. The secret is placing the encoder in the heavy, machined aluminum clutch housing and removing it fast.

Available in 7-bit to 13-bit models and industry-standard absolute, incremental or linear output formats, the magnetic encoders deliver high-resolution positioning (up to 8,192 count per revolution), speeds to over 30,000 rpm, while withstanding temperatures from -40°C to +125°C, high levels of shock, vibration, acceleration and pressure.

Easy to integrate, the RLS mini mag encoders come in component, modular and packaged versions. Miniature size requires a fraction of the area for optical encoders, solving tight packaging situations. Designers who require the smallest possible encoder can incorporate encoder components or modular solutions into their own design. Packaged versions are available in non-contact (RM) versions or traditional bearing/shaft format (RE). Compact sealed versions are available with protection to IP68 for harsh environments, including immersion applications (e.g., pumps and gearboxes).

At the heart of every Renishaw magnetic rotary encoder are two core components — a small diametrically polarized magnet and a custom Hall sensor ASIC which contains an array of Hall effect sensors that generate a voltage when exposed to a magnetic flux field. The ASIC detects the change in magnetic flux as the magnet rotates above it. Through creative design, the ASIC is able to cancel magnetic interference, enabling it to operate in areas of high external magnetic fields and cope with imperfections in the shape of the flux field of the actuating magnet.

The RM22's non-contact, two-part design eliminates bearings or seals, allowing for rapid, easy installation and removal.

For more information, contact: Renishaw, Inc., 5277 Trillium Blvd., Hoffman Estates, IL 60192 847-286-9953 fax: 847-286-9974 Web:

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