Arrangement for detecting the angular position of a rotatable part

Abstract

An arrangement for detecting the angular position for a rotatable part, for example, the printing head of an office machine comprises a shaft coupled to the rotatable part for rotating in synchronism therewith, a first rotatable cylinder arranged to rotate with the shaft and having disposed along a circumferential track a plurality of recognition apertures which are associated with predetermined discrete angular positions of the rotatable part. A first detecting unit is arranged to co-operate with the plurality of apertures to detect the predetermined discrete angular positions of the rotatable part. A second rotatable cylinder is rotatably mounted inside the first cylinder and is coupled to the shaft through speed reduction gears. On the second cylinder there is disposed at least one synchronizing element co-operating with a second detecting unit to detect complete revolutions of the rotatable part. The number of discrete angular positions of the rotatable part is equal to the number of the plurality of recognition apertures multiplied by the speed reduction ratio between the shaft and the second rotatable cylinder and divided by the number of synchronizing elements of the second cylinder.

Dependencies are inferred from the claim text.