| 摘要 |
The gearwheel and shaft (3) are rotated, and are illuminated with a narrow light beam (2) from a source (1), the light being directed so that it is reflected against one of the gear teeth. A part of the reflected light can be picked up by a lens (5) which focusses it on to a spot on a plane (6) in which a position-sensitive detector or two photo detectors are located. The detectors are so placed that the light spot moves over first one and then the other detector as the reflecting surface on the gear tooth moves during the rotation of the gearwheel. Thus, the relationship between the output signals from the position-sensitive detectors is proportional to the position of the spot, and such signals are compared in a comparator. - The time when the output signals are equal is recorded by a microprocessor, and a number of times are recorded, the mutual spacing of which corresponds to the time between two gear teeth passing the same point. The time intervals give an indication of the differences or similarity between the shape and position of individual gear teeth along the periphery of the gearwheel. |
