Geometrical instruments – Distance measuring – By flexible tape
Reexamination Certificate
2000-04-17
2001-10-30
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Distance measuring
By flexible tape
Reexamination Certificate
active
06308432
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed generally to a twist lock mechanism and, more particularly, to a tape measure having a pivotable locking mechanism selectively positionable between engaged and disengaged orientations.
BACKGROUND OF THE INVENTION
Tape measures generally include a coiled tape that is spring biased towards a retracted position. A protective housing surrounds the tape and spring and includes an aperture through which a distal end of the tape extends. The distal end of the tape is pulled away from the housing during use in an extended position, and when released, the spring pulls the tape back into the housing such that the tape assumes the retracted position.
Various types of locking mechanisms are utilized for maintaining the tape in the extended position. Locking mechanisms are usually actuated by the user through a slide or push button positioned on an outer edge of the housing. Thus, the tape may be extracted to the desired length and the locking mechanism engaged to hold the tape at that distance. The locking mechanism may then be disengaged and the tape is retracted into the housing.
Many currently existing tape measures feature complicated locking mechanisms for holding the blade in the extended position. These locking mechanisms include a plurality of intermeshing parts which mate together and are selectively moveable between the open and engaged orientations. One drawback of these complicated locking mechanisms is that they result in a higher selling price to the consumer. The numerous individual pieces are often expensive to produce and assemble. Another drawback is that these complicated locking mechanisms are easily damaged if they are roughly handled, dropped, exposed to moisture or debris, and other like treatment.
Further, with existing locking mechanisms it is sometimes difficult for the user to determine when the mechanism is in an engaged or locked orientation. In one common embodiment, the device includes a thumb lock positioned on a front edge of the outer housing such as that disclosed in U.S. Pat. No. 4,489,494. The locking bar is selectively positionable between locked and unlocked orientations. As the thumb lock is slid from the unlocked towards the locked orientation, it is difficult for a user to determine whether it is in a full locked position that will restrict the tape from being retracted into the housing. Preferably, the locking mechanism provides for a definitive locked position in which the user can be assured that the locking mechanism is fully engaged to restrict retraction of the tape blade.
Thus, there is a need for a locking mechanism having a minimum of moveable parts, have adequate durability for use in harsh environments, and be positively locked in an engaged orientation to prevent tape retraction.
SUMMARY OF THE INVENTION
The present invention is directed to a tape measure having a twist lock mechanism for controlling the retraction and extraction of a tape measure. In one embodiment, the device includes a housing with a measuring tape disposed substantially therein and being moveable between an extended position and a retracted position. A locking member is rotatably mounted in the housing about an axis substantially orthogonal to the tape between a first orientation spaced from the tape and a second orientation contacting the tape.
The tape measure housing may include locking mechanism openings, and the locking mechanism may include an actuator that extends through the openings for rotating the locking mechanism between the first and second orientations. The locking mechanism may also include a substantially crescent-shaped head for contacting the tape. Ribs may extend from the housing adjacent to the tape such that the tape is deformed between the ribs and the crescent-shaped head in the engaged orientation to restrict movement of the tape.
In the disengaged orientation, the head may be substantially parallel with a centerline of the tape blade. In the engaged orientation, the head may be substantially perpendicular with a centerline of the tape blade. The tape blade may have a substantially concave shape having outer ends which extend upward from a middle section and the head may contacts the tape outer ends in the engaged orientation. Preferably, the head has a radius of curvature larger than the tape blade.
REFERENCES:
patent: 4288923 (1981-09-01), Duda
patent: 4489494 (1984-12-01), Duda
patent: 4697349 (1987-10-01), Lee
patent: 4927092 (1990-05-01), Ingram, II et al.
patent: 4938430 (1990-07-01), Chapin
patent: 5001843 (1991-03-01), Chapin
patent: 5210956 (1993-05-01), Knispel et al.
patent: 5379523 (1995-01-01), Wingert
patent: 5657551 (1997-08-01), Lin
patent: 6139373 (2000-10-01), Mann
patent: 6272764 (2001-08-01), Lin
patent: 6276071 (2001-08-01), Khachatoorian
patent: 0 066 322 (1982-05-01), None
Gilliam Edgar T.
Moody John B.
Bennett G. Bradley
Coats & Bennett, P.L.L.C
Cooper Brands, Inc.
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