LINEAR DISPLACEMENT MEASURING APPARATUS FOR DETERMINING AN ABSOLUTE POSITION, AND LINEAR GUIDE HAVING SUCH A DISPLACEMENT MEASURING APPARATUS

摘要

The linear displacement measuring apparatus (10) for determining an absolute position comprises a linear rail (30) which is composed of individual rail segments (30a, 30b) arranged after one another in the direction of a longitudinal axis. Each of the rail segments has a material measure (40a, 40b) which comprises at least one incremental track (41.1) which extends along the longitudinal axis and has equidistantly arranged position markings. In addition to the incremental track (41.1), the material measure (40a) of one of the rail segments (30a) has an absolute track (45) with position markings for coding a plurality of absolute positions. A scanning device (50) can be moved along the rail segments and comprises a sensor arrangement for scanning the material measures (40a, 40b) with a first sensor (51.1), a second sensor (51.2) and a third sensor (51.3). The first sensor and the second sensor are arranged in a manner offset relative to one another in the direction of the longitudinal axis and are used to detect the position markings of the incremental track (41.1). The third sensor detects position markings of the absolute track (45) of the material measure (40a) of the one of the rail segments (30a). An absolute value (AW2) for an absolute position of the scanning device (50) can be calculated from signals (S1, S2, S3) from the sensors (51.1, 51.2, 51.3).