ESF Thüringen - Liste der Vorhaben Förderperiode 2014-2020

Quality control of linear and rotary encoder

Real time geometry and field intensity quality control of magnetizations of linear and rotary encoders

magview-linear-encoderA linear or rotary encoder is a sensor, transducer or readhead paired with a scale that encodes position or angular rotation. The sensor reads the scale in order to convert the encoded position into an analog or digital signal, which can then be decoded into position by a digital readout controller. The encoder can be either incremental or absolute. Motion or rotation can be determined by change in position over time. Linear encoder technologies include optical, magnetic, inductive, capacitive and eddy current.     While linear encoders are mainly used in metrology instruments, motion systems and high precision machining tools ranging from digital calipers and coordinate measuring machines to stages, CNC Mills, manufacturing gantry tables and semiconductor steppers, rotary encoders are of growing demand espeacially in electrical motor industries and therefore electrical mobility.

In order to provide best measurement capabilities of the used linear or rotary encoders, it is necessary to control and check the quality of the installed magnetic encoder band and its magnetization qualities. The magview und cmos-magview can be used to assure geometric, as well as magnetic properties of all types of magnetic encoders.


Geometric quality control of linear encoder tapes

In order to measure and visualize the geometric pattern of magnetic linear encoder tapes the cmos-magview  or handheld magview s supported with a magneto-optical chip working in clipping mode. Therefore hard magnetization boundaries can be identified and analyzed very easily and on demand automated for 100% production control.




Encoder with geometric failure clearly visible in MO-image and analysis chart.


Quality control of magnetic properties of linear encoder tapes

In order to measure magnetitization intensities or magnetization states of a lineary encoder band a chip of type B is commonly best suited. By using the cmos-magview evaluation software magnetization intensities can be measured precisely and the changes or uniformity of field intensity amplitudes can be controlled in real time.




Measurement of magnetization intensities and amplitudes of encoder tape.



For comparison: green foil is not capable of identifiyng geometry defects. Furthermore there is no possibility of analysis of magnetic field intensities or pole orientation.


Quality control of magnetic properties and geometry of rotary encoder structures

A rotary encoder, also called shaft encoder converts the angular position or motion of a shaft or axle to an analog or digital code. Rotary encoders are often used to track the position of the motor shaft on permanent magnet brushless motors, which are commonly used on CNC machines, robots, and other industrial equipment as well as electrical automobility motors. To ensure reliability and functionality of the motor product it is highly recommended to check rotary encoders regarding to magnetization geometry as well as intensity.




Visualization of magnetization structures and amplitudes of rotary encoder.