Geometrical instruments – Distance measuring – By flexible tape
Reexamination Certificate
1999-08-04
2001-12-04
Hirshfeld, Andrew H. (Department: 2859)
Geometrical instruments
Distance measuring
By flexible tape
C033S757000, C033S769000
Reexamination Certificate
active
06324769
ABSTRACT:
The present invention is generally related to retractable tape rule assemblies and more particularly to tape rule assemblies of the spring retractable type.
BACKGROUND OF THE INVENTION
Spring retractable rule assemblies have been available commercially for many years. One of the most desirable characteristics commercial rule assemblies can possess is a relatively long blade standout. To date, as a practical matter, that standout length of most blades has rarely exceeded 7 feet or at most approximately 9 feet. Standout is generally measured by the length of the rule assembly blade that can be extended in a self-sustaining manner without the blade buckling under its own weight. An important characteristic of standout relates to the vertical bend that the blade takes in its maximum self-sustained extension. This is generally expressed in terms of the height the housing assumes from a horizontal surface when the free end of the blade is just touching the horizontal surface. The vertical height of the housing above the horizontal surface, the position at which the free end of the blade touches the horizontal surface and the vertical projection of the position of the housing onto the horizontal surface roughly define three points of a right angle triangle. The hypotenuse of the triangle represents a close approximation of the actual length of the blade extending from the housing and the horizontal leg of the triangle represents the linear horizontal extension of the blade. It is generally recognized to be desirable to maintain the ratio between the linear horizontal extension to the actual extension as near to one as possible. There always exists a need to provide a retractable rule assembly that will provide greater standout with a greater ratio of linear horizontal standout to actual standout.
BRIEF DESCRIPTION OF THE INVENTION
An objective of the present invention is to fulfill the need expressed above. In accordance with the principles of the present invention, this objective is achieved by providing a retractable rule assembly that includes a housing assembly and a reel rotatably mounted in the housing assembly. An elongated blade formed of a ribbon of metal is mounted on the reel. One end of the blade is connected to the reel. The blade 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 that is 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 the elongated blade about the reel when the blade is extending outwardly of the housing assembly opening. The blade has a “normal” concavo-convex cross-sectional configuration when extended and has a flat cross-sectional configuration when it is wound about the reel so that the wound reel is disposed about the reel in an abutting volute coil formation. A blade holding assembly is provided which is 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. The blade has a blade width, thickness and height of concavo-convex curvature sufficient to enable the blade to stand out arcuately a length measured along the blade of approximately 11 feet with a horizontal linear length of standout thereof greater than 97% of the arcuate length of standout.
Preferably, the width of the elongated blade in its flattened configuration is within the range of 1.10″-1.5″; the height of the elongated blade in its concavo-convex configuration is within the range of 0.25″-0.40″; and the thickness of the elongated blade in either configuration thereof is within the range of 0.0045″ to 0.0063″.
The geometry of the cross-section of the extended blade is also important in increasing blade standout. Preferably, the concavo-convex cross-sectional configuration of the elongated blade includes an arcuate central section having a predetermined radius of curvature and integral arcuate end sections each having the same radius of curvature (i.e., the radius of curvature of one integral arcuate end section is equal to the radius of curvature of the opposite integral arcuate end section); preferably, the radius of curvature of the central section is a dimension within the range of 0.35″ to 0.60″ and the radius of curvature of each end section is a dimension within the range of 1.0″ to 5.0″.
It is contemplated to provide a wide range of tape assembly embodiments having increased blade standout. More particularly, in the more specific aspects of the present invention, it is a further objective to provide a retractable rule assembly having a blade constructed according to the principles briefly described above to provide the improved standout characteristics previously described with any combination of the following additional features:
1. A retractable rule assembly wherein a relatively short free end portion of the blade has a clear film of plastic material adhered to a concave side thereof.
2. A retractable rule assembly wherein the metal ribbon of the spring has a width which is 95%-120% of the width of the metal ribbon of the blade.
3. A retractable rule assembly wherein the blade has an end hook member on the free end thereof, the end hook member being formed of sheet metal of a predetermined thickness to include a concavo-convex mounting portion having a U-shaped hook portion bent at a generally right angle from an end thereof, the end hook member being mounted on the free end of the blade with the mounting portion thereof secured in limited sliding engagement with a concave side of the free end of the blade so that the rule can be measured externally from an exterior surface of the U-shaped hook portion or internally from an interior surface of the U-shaped hook portion, the U-shaped hook portion including a bight section extending transversely from a convex side of the free end of the blade and spaced leg sections extending beyond transversely spaced corners of the free end of the blade.
4. A retractable rule assembly wherein the housing assembly includes a pair of cooperating housing members, each including an end wall having a peripheral wall extending from a periphery thereof and terminating in a free edge, the housing members being fixed together with their free edges interengaged by a plurality of bolts extending through one of the housing members and threadedly engaged in the other at spaced positions adjacent the peripheral walls thereof and by a fixed reel spindle having a non-circular interengaging recess-projection connection at each end thereof with the central interior of the adjacent end wall, each end of the spindle being interiorly threaded to threadedly receive a bolt therein extending through a central hole in the adjacent end wall and the recess-projection connection between the central hole and threaded interior.
5. A retractable rule assembly wherein the housing assembly includes a fitment defining a part of the housing assembly opening adjacent a convex side of the blade, the fitment having a plurality of tangentially extending transversely spaced elongated ridges defining surfaces for engaging the convex side of the blade extending tangentially from the reel to said housing assembly opening.
6. The housing assembly includes a bottom wall having an exterior portion at an end position adjacent the housing assembly opening which projects below the exterior surface portion extending therefrom toward an opposite end to provide a finger grip enhancing configuration.
7. The housing opening has a height dimension which exceeds the height dimension of the blade an amount that is at least approximately equal to the amount the hook portion extends below the bottom end surface of the housing assembly at the housing opening.
In the broader aspects of the present invention, it is an objective to provide any known retractable rule assemb
Hirshfeld Andrew H.
Pillsbury & Winthrop LLP
Smith R. A
The Stanley Works
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