Miniaturized optical rotary encoder

Angle measurement in narrow spaces has so far been an almost impossible task. Especially, if an optical method is to be used and a high resolution is required, a satisfactory solution has not yet been found. Hahn-Schickard, in collaboration with IMS Chips, has found a new approach to solving this task.
 
The basic idea of the new method is to integrate the angle information directly on an opto-ASIC. This makes it possible to realize encoder discs with very small diameters (> 1 mm). Large diameters or even encoder discs for hollow shafts are also possible. On the encoder disc there is only a uniformly structured diffraction grating, which is optically scanned. Upon rotation of the shaft or encoder disc, a light spot on the opto-ASIC rotates similarly to an optical pointer. With this approach, the rotary encoder is free from measurement errors, which occur in conventional rotary encoders due to unavoidable eccentricities between encoder disc and rotary shaft and can only be minimized with major adjustment efforts.
 
The demonstrator was able to achieve a resolution of 10 bits within a diameter <10 mm. The optical concept allows the angular information to be provided both in absolute and in an incremental way, other combinations are also possible. If a higher resolution is required, this can be achieved by interpolation methods. Special interfaces can be realized with the help of the opto-ASIC.
 
The competencies of Hahn-Schickard in the field of the design and development of miniaturized optical systems, as well as their production and characterization, are illustrated by the example of this miniaturized optical rotary encoders. Due to the simplicity of the design, production costs for an industrial implementation of the concept are expected to be low. Any connection of the system to a specific application can be designed individually.
 
Contact: Hahn-Schickard, Claudia Feith, Claudia.Feith@hahn-schickard.de