| 摘要 |
A measurement apparatus has five light barriers (L1... L5) of which three (L1, L2, L3) lie at a determined mutual distance (M1, M2, M3) in a first plane (E1) parallel to the vehicle running track at the site of use of the measurement apparatus, forming three pairs (P1, P2, P3) of light barriers. Two light barriers (L4, L5) are arranged in a parallel plane (E2) thereto as a fourth light barrier pair (P4) at a mutual distance (M4) equal to the distance (M3) between the light barriers (L2, L3) of one light barrier pair (P3) among the three light barrier pairs (P1, P2, P3) located in the first plane (E1). Four time measuring devices measure the time elapsed between the interruption of the first light barrier and the interruption of the second light barrier of the same light barrier pair. In an evaluation circuit, the times elapsed between the interruption of the light barriers of determined light barrier pairs are on the one hand compared with each other and on the other hand with the distance that separates both light of the corresponding light barrier pair. When the comparison values coincide, the ratio between the distance (M3) that separates both light barriers (L1, L3) of one light barrier pair (P3) and the time (T3) elapsed between their interruption is formed and displayed and/or recorded as a speed value. |
