| 摘要 |
A retractable rule assembly includes a housing assembly and a reel rotatably mounted in the housing assembly. An elongated blade formed of a ribbon of metal having one end connected to the reel is constructed and arranged with respect to the housing assembly to extend from a position tangential to the reel outwardly through a spaced opening in the housing assembly. A coil spring formed of a ribbon of metal has a construction and arrangement between the housing assembly and the reel to rotate the reel in the housing assembly in a direction to wind up the elongated blade when extending outwardly of the housing assembly opening in a normal concavo-convex cross-sectional configuration onto the reel in an abutting volute coil formation in a flattened cross-sectional configuration. A blade holding assembly is constructed and arranged to be manually actuated to hold the blade in any position of extension outwardly of the housing assembly opening and to release the blade from any position in which it is held. A relatively short free end portion of the blade has a clear film of plastic material adhered to a concave side thereof. The clear film of plastic material protects the covered portion of the blade from cracking or tearing and protects the numbering and graduation lines on the end of the blade from wear.
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