Patent Application
20070079520
This invention relates generally to tape measures and, more particularly, to a tape measure blade having an improved construction and a method for manufacturing the tape measure blade.
Tape measures typically consist of a flexible tape or blade that is wound on a reel within a housing. The blade is stored in the housing in a wound state and it is unwound and extended from the housing to measure linear distances. The blade can be rewound back into the housing either manually, such as by rotating an external crank, or automatically, such as by use of an internal spring. One typical blade consists of a thin steel strip having measurement indicia printed on a surface thereof such that when the blade is extended from the housing a user can measure linear distances by reading the indicia.
A problem with known blade designs is that over time the printed material wears off of the blade from use. As will be understood tape measures are subjected to relatively harsh conditions where they are used outdoors in all types of weather and under abrasive conditions on construction sites and the like. Moreover, the design of tape measures adds to the wear on the printed material. The repetitive winding and unwinding of the blade causes the printed material on the blade to contact and wear against any surface it contacts. Also, as the blade is retracted it has a tendency to “whip” as the blade enters the housing. This is especially true with automatic tape measures where the spring force applied to the blade causes the blade to accelerate as it retracts into the housing. The whipping of the tape measure blade against the housing further increases the wear of the printed material.
As the printed material wears off the blade, reading the indicia may become difficult or impossible leading to inaccuracies in measurement and unacceptable performance of the tape measure. Because the printed material may wear away before the other structural elements of the tape measure fail, the wear can be a source of frustration for the end user and may present an inaccurate indication of the overall quality of the tape measure.
Thus, an improved tape measure having a blade with improved wear characteristics and a method for manufacturing such a blade is desired.
The invention comprises a tape measure blade having improved wear characteristics, a tape measure utilizing such a blade, an a method of manufacturing such a blade. The blade of the invention includes a thin blade that is flexible enough to be wound on a reel in a tape measure housing. The blade may be formed as is known in the art to have a transverse cross-sectional shape that increases the rigidity of the blade and allows it to extend unsupported from the housing. A clear film made of polyester, nylon or other flexible, strong and relatively thin material is provided with the measurement indicia printed on one side thereof. The film is attached to the blade with the printed side contacting and secured to the blade such that the side of the film without printing is the side of the film exposed to the environment. Because the printed material is on the inner surface of the film, the printing is not in contact with the external environment and will not be worn away during normal use. Because the film is transparent the printed material is visible through the film.
Referring to
It will be appreciated that unwinding and extending blade 14 is typically done manually while the rewinding of the blade back into the housing is typically done automatically. To automatically rewind the blade, hub assembly 10 includes a spring 11 connected to hub 12 such that extension of the blade 14 deforms the spring to store energy therein whereby when the blade is released the spring releases the stored energy to rotate the hub 12 and rewind the blade. It is also known to provide tape measures in which the blade can be extended automatically using a motor and/or the blade can be retracted manually using an external crank.
To counter the rewind force of the spring and maintain the blade in the extended position a brake 22 is provided. Brake 22 may consist of a sliding member 24 that moves between a first position in which it contacts the blade 14 to trap the blade between member 24 and housing 2 to maintain the blade in an extended position and a second position where the member 24 does not contact the blade 14 such that the blade can be freely extended or retracted.
Blade 14 has one end connected to hub 12 and an opposite end extending from housing 2 and connected to an end hook 26 via fasteners 28 such as rivets. End hook 26 is used to prevent retraction of the blade 14 completely into the housing 2 and to temporarily secure the blade to a surface during use of the tape measure.
Referring to
A film 30 is applied to the upper surface 14a of blade 14. The film 30 is a thin length of transparent, durable and flexible material such as polyester, polyethylene, polyurethane, polypropylene, nylon or the like having a thickness of 0.001 to 0.015 inches. Measurement indicia, other markings and/or other printed material 32 are printed on the inner surface 30a of film 30. The “inner surface” as used herein refers to the surface of the film that contacts and is attached to the blade after the blade is assembled. The “outer surface” refers to the surface 30b of the film 30 that is exposed to the environment in the assembled blade. The measurement indicia may consist of linear units in the metric or English systems or both. The other markings or printed material may consist of branding information, application specific information such as sixteen inch “on center” stud markings or the like.
The film 30 is attached to the blade 14 by an adhesive such that the film is permanently and securely attached to the blade. The film is permanently affixed to said blade such that in normal operation of the blade, the film remains secured to the blade. An adhesive such as silicone or acrylic may be used. In one embodiment the film 30 extends over the entire upper surface 14a of the blade 14 for the entire length and width thereof.
Because the printed material 32 is on the inner surface 30a of the film 30, the unprinted outer surface 30b of the film is exposed such that the thickness of the film protects the printed material 32. In this manner the printing will not degrade or wear from the extension and retraction or use of the blade. Because the film 30 is transparent the printed material 32 is clearly visible to the end user through the film. The printed material 32 is printed on the inner surface of the film in reverse such that the printed material will be in the proper orientation for reading by the end user when viewed through outer surface 30b.
An alternate embodiment of the invention is shown in
While a separate first film 30 and second film 34 may be used, a single film 38 having both top markings 40 and bottom markings 42 may be used as shown in
One method of manufacturing the blade of the invention will be described with reference to
Another alternative to the method of manufacture, is to print the indicia and markings in a separate process such that coil 56 has wound thereon preprinted film stock. It is also contemplated that film pretreated with adhesive may be used. If such film is used it would typically be wound on coil 56 with a backing material placed over the adhesive to prevent the layers of film from sticking to one another. The backing material is removed from the film before the film enters the printer. In this embodiment the separate adhesive application step may be omitted. It is further contemplated that if film is to be applied to both sides of the blade, the film may be applied to both sides of the blade in a single process or the process may be repeated for each side of the blade.
Specific embodiments of an invention are disclosed herein. One of ordinary skill in the computing and financial arts will quickly recognize that the invention has other applications in other environments. Many embodiments are possible. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described above.
