| 摘要 |
On the free end of the arm (16) extending sideways from the movable carriage (10) is arranged a pressure-monitoring component (161) which on activation causes the ignition of a light source (18) placed on the carriage (10). A measurement unit (20) transmits light towards the first prism (14) when measurement commences and towards the second prism (13) on the pressure-monitoring component (161) activation. The distance between the free end of the arm (16) and the carriage centre is calculated dependent upon the light reflected by the prisms and received by the measurement unit (20). The extendable arm is arranged for movement at right-angles from one side of the carriage (20). |
