Patent ID: 9579045
Date: 2017-02-28
CPC Classifications: A61B,G01B

Claim:
1. A length measuring device comprising: a measuring slide, a linear guide comprising a hollow profile, on which the measuring slide is mounted so as to be externally displaceable, to be able to bring the measuring slide into contact with an object to be measured with respect to an object length, an inner slide, which is mounted so as to be displaceable in an interior of the hollow profile, a magnet assembly, which magnetically couples the measuring slide and the inner slide, so that the inner slide follows every movement of the measuring slide along the hollow profile, a measuring unit for measuring a position of the inner slide along the hollow profile, and a display, which is visible in an exterior of the hollow profile, of a measured object length ascertained by the measuring unit in accordance with the measured position of the inner slide, wherein the measuring unit includes a sound source, a sound receiver, and a control and analysis unit connected to the sound source and the sound receiver, wherein the control and analysis unit is configured to excite the sound source to emit a sound signal and to analyze representative output signals of the sound receiver, to determine a runtime of a first reflected sound signal reflected on the inner slide at a reflection location and to calculate the position of the inner slide along the hollow profile, wherein the control and analysis unit is furthermore configured to capture a further reflected sound signal represented in the output signals of the sound receiver, wherein the further reflected signal has been reflected at a known point along the hollow profile or at a known distance from the reflection location of the first reflected sound signal, and to cause a runtime of the further reflected sound signal to be incorporated as a reference measurement in the calculation of the position of the inner slide.