Patent ID: 7406772
Filing Date: 2008-08-05
Classification: G01D,H03M

Abstract:
1. 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 ).