Method and apparatus for detecting abnormal thickness conditions such as folded and/or missing corners of moving sheets

摘要: Sheets moving in a feed direction and arranged at spaced intervals are fed through nips to rollingly engage opposing sides of the sheet, each nip being formed by roller rotating about fixed axis cooperating swingably mounted roller. Resilient adjustable biasing means urges an assembly upon which is pivotally mounted, as well arm forming part assembly, first direction. A sensor positioned adjacent free end said arm. cause displacement pivotal against force accordance with thickness sheet passing nip. The comprises thick, accurate resilient element designed permit follow even abrupt changes rapidly accurately without experiencing overshoot or undershoot. senses position field generating provide signal representative size displacement. output signals developed during passage compared threshold. sensors periodically examined offset for automatically compensating strength due temperature, new zero generated time that no between aforesaid nips. combined compensated then reference level representing predetermined thickness.