Device for measuring the position, the path or the rotational angle of an object

Device for measuring the position, the path or the angle of rotation of an object, comprising a scannable material measure which can be connected to the object and assigns measurement values to a position range of the object, these measurement values being cyclically repeated in successive position ranges of the object, and comprising a coding unit, which codes the number of passed-through measurement value cycles and has at least two code discs driven via reduction gears of the material measure, wherein the code discs (3, 4, 5) have an absolute angle coding (34, 44, 54), wherein the code discs (3, 4, 5) are coaxially disposed and have axially mutually offset gears (30, 40, 45, 50), wherein the respectively successive code discs (3, 4 and 4, 5) are coupled in such a way by a differential gearing (21, 30, 40 and 22, 45, 50) that they are jointly driven by means of a drive gear (21 and 22) and their gears (30, 40, 45, 50) respectively have different tooth numbers, and wherein the number of passed-through measurement value cycles is determined from the mutual angular position of the code discs (3, 4, 5), characterized in that the gears (30, 40, 45, 50) of all of the code discs (3, 4, 5) are of annular configuration, in that the code discs are mounted one against the other such that they are freely rotatable, in that the code tracks (34, 44, 54) of the angle codings of the code discs (3, 4, 5) are located in a single plane on concentrically disposed annular discs (33, 43, 53) in the free interior of the gears (30, 40, 45, 50), and in that the code tracks (34, 44, 54) of all code discs (3, 4, 5) are irradiated by a joint light transmitter (14) with light path running in the free interior of the gears (30, 40, 45, 50) and are scanned by a scanner (15) radially sweeping the code tracks (34, 44, 54) of all of the code discs (3, 4, 5).