| 摘要 |
Apparatus for measuring thickness, two light measuring heads (2, 3) being mounted by air bearings in housings on either side of the web (1). The measuring heads are provided with specially implemented nozzles blowing against the surface and maintaining a constant distance of 60-100 mu m to the respective paper surfaces. The thickness is measured by the distance between the nozzles being measured via an electrical measuring probe (13) in one, and a means (13') sensed by the measuring probe. By the especial implementation of the nozzles (12, 12') and by their being pneumatically pressed (via 11) against the surfaces, high accuracy (better than 0.5 mu m) can be achieved, and this is so even if the position of the paper is altered, rapidity also being considerable. The time to indication for a thickness alteration of about 100 mu m is about 0.5 ms. |
