Automatic umbrella having rib assembly formed with light grooved rib reinforced resilient rib

摘要

An automatic umbrella includes: a top rib and a stretcher rib each having a cross section of U shape or the like shape and made of light material including aluminum alloy, an outer rib gradually tapered outwardly and an auxiliary stretcher rib each having a cross section of circular shape or the like shape and made of composite or plastic materials having good resilience and mechanical strength to be respectively connected with the top rib and the stretcher rib, a flattened tensioning spring jacketed on the shaft and retained between a middle runner arid a lower runner having a cross section of the spring ring formed as rectangular shape for forming a slim umbrella shaft, and a top cap member firmly fixed on a top of the shaft, thereby providing an automatic umbrella having light weight, better resilience and strength, slim structure, and firmly fastened top cap.