BEI Encoder Products - BEI Sensors

An Overview of the Rotary Encoder

There are two types of mechanical configurations for optical encoders: rotary encoders and linear encoders. Optical rotary encoders are most commonly found in motion control systems while linear encoders are used more specifically for linear-positioning applications such as piston or actuator monitoring systems.

A rotary encoder uses an optical sensing technology which relies on the rotation of an internal code disc that has opaque lines and patterns on it. The disc is rotated (hence the name rotary encoder) in a beam of light such as an LED and the markings on the disc act as shutters blocking and unblocking the light. An internal photodetector senses the alternating light beam and the encoder's electronics convert the pattern into an electrical signal that is then passed on to an external control system through the encoder's output.

Rotary encoders are also available in two formats: incremental or absolute. Check out our page on optical rotary encoders for more information.

Rotary encoders can be built in two different body styles: shafted or hollow shaft.

Shafted vs. Hollow Shaft Rotary Encoders
Shafted Rotary Encoders	Hollow Shaft Rotary Encoders
A shafted rotary encoder is built so that the rotor portion of the encoder is a short shaft that is usually attached through a flexible coupling to the shafts of various motion control equipment. The body of the shafted rotary encoder is commonly fixed by a rigid mounting bracket. See BEI shafted rotary encoder product line	A hollow shaft rotary encoder is composed in a way so that the rotor portion of the encoder is tubular, with the inner diameter of the rotor tube sized to accept and clamp to most standard shaft sizes. This style does not require the use of a coupling, however, the body of the rotary encoder must be constrained by a flexible tether arrangement. See BEI hollow shaft rotary encoder product line

BEI Industrial Encoders (IED) is a company of Custom Sensors & Technologies (CST). IED manufactures optical encoders, rotary encoder products, position sensors and associated electronics for the industrial market and motion control applications. IED is the market-leading brand of encoders in North America.

About Custom Sensors & Technologies
Headquartered in Moorpark, Calif., Custom Sensors & Technologies (CST) is comprised of industry-leading brands including Crouzet, Kavlico, Crydom, and former divisions of BEI Technologies – Newall and Systron Donner. CST provides sensors, controls, and actuation products for the Transportation, Industrial and Aerospace & Defense markets.