| 摘要 |
There is provided an arrangement for maintaining in a first plane (1) the direction of a direction indicator (4) that is carried by a carriage (3) for parallel movement along a substantially straight guide (2) that extends parallel with said plane. The carriage (3) includes a first part (31, 32) which is guided by the guide (2; 21, 21'), and a second part (4) which carries the direction indicator (5) and which can be rotated about an axis (61) that intersects the plane (1) and that is generally perpendicular to the longitudinal direction of the guide (2). The arrangement also includes a reflector (12) which is generally perpendicular to the longitudinal direction of the guide (2) and which is mounted at an end region of the guide (2) or in the extension of said guide. The second carriage part (4) carries a light beam emitter (8) which emits generally parallel with the longitudinal direction of the guide a beam that can impinge upon the reflector (12). This second carriage part also carries a light sensor (10) which is adapted to detect a beam emitted by the emitter and reflected by said reflector (12) when said second carriage part (4) is rotated, so that the direction indicator (5) will take the same direction in the plane (1) with the various positions of displacement of the carriage along the guide (2).
|
