Roll-to-roll printing on continuous plastic films could enable the production of flexibleelectronics at high speed and low cost, but the granularity of feature sizes is limited bythe system accuracy.Technologies such as gravure printing and nanoimprint lithography demand a levelof rotary motion precision that cannot be achieved with rolling element bearings. Manufacturingtolerances of the rotating parts, thermal drift and process forces in combinationwith structural compliance add up to additional error motions.In this master by research an active magnetic bearing (AMB) solution is designedfor a new, super-sized roll-to-roll flexible electronics production machine, which was sofar based on hydrostatic bearings. The magnetic bearing could actively compensate theaccumulated synchronous error and maintain high accuracy under all conditions.However, the asynchronous error of a conventional AMB with the required size andpower is a problem. In order to reduce the relatively high positioning uncertainty of activemagnetic bearings an innovative radial position measurement based on linear, incrementalencoders with optical conversion principle is proposed. A commercial encoder scanninghead faces a round scale with concentric, coplanar lines on its face. By counting theselines the radial position can be measured.Because such a scale is not readily available, it is made by micro-machining. Inexperiments, different machining methods are compared. Then a magnetic bearing isbuilt to demonstrate the efficacy of the proposed sensor. As a result, the best measurementnoise is 3.5nm at 10kHz and a position uncertainty of approximately 0.25µm has beenachieved for the magnetic bearing. These promising results are especially interesting forapplications with high precision requirements at low speed of rotation.
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