Electricity: measuring and testing – Conductor identification or location – Inaccessible
Reexamination Certificate
2001-10-05
2004-02-24
Snow, Walter E. (Department: 2862)
Electricity: measuring and testing
Conductor identification or location
Inaccessible
C324S228000
Reexamination Certificate
active
06696827
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
(Not Applicable)
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
(Not Applicable)
BACKGROUND OF THE INVENTION
The present invention relates generally to magnets, and more particularly to a magnetic locator device suited for determining the location of embedded metallic objects such as wall studs, and providing a visual reference point corresponding to the location of such objects.
There is known in the prior art numerous stud finder devices which employ the use of a magnet to determine the location of a fully or partially embedded metallic object, such as a metal wall stud or a nail. Examples of such prior art stud finders are found in U.S. Pat. No. 3,845,384 entitled STUD FINDER, U.S. Pat. No. 4,700,489 entitled SQUARE LEVEL MEASURING TOOL, U.S. Pat. No. 4,896,131 entitled STUD FINDER WITH ONE-PIECE MAGNET ASSEMBLY, U.S. Pat. No. 5,148,108 entitled STUD FINDER WITH LEVEL INDICATOR, and D339,074 entitled STUD FINDER. In each of these prior art references, a relatively small, cylindrically configured magnet is pivotally or rotatably connected to a housing. When the housing is placed upon a surface such as a wall, and is not in close proximity to a metallic object such as a nail or a metal wall stud, the magnet typically extends along a first axis which extends in non-perpendicular relation to the wall. As the stud finder is slid along the surface of the wall to a location over a nail or an embedded metal wall stud, the force of magnetic attraction between the magnet and the nail or metal wall stud facilitates the pivotal movement of the magnet to a position whereat it extends along a second axis which is generally perpendicular to the wall, thus providing a visual indication that the stud finder is located over the nail or embedded metal wall stud. At this point, a scribe, pencil or other marking device is used to make a mark on the wall indicative of the location of the nail or metal wall stud.
Though the above-described stud finders are generally suitable for determining the location of a fully or partially embedded metal object, they possess certain deficiencies which detract from their overall utility. More particularly, as indicated above, the size of the magnet included in such prior art stud finders is relatively small, with the size being limited to the minimum needed to exert a level of magnetic force sufficient to cause the magnet to be pivoted to extend along an alternative axis once moved into a location adjacent or in close proximity to a metal object. Thus, the small size of the magnet is wholly insufficient to maintain the stud finder upon the vertical wall surface or a ceiling without external support. Indeed, as also indicated above, a scribe, pencil or other marking device must typically be used with such prior art stud finders to provide a permanent visual reference point corresponding to the location of the underlying metal object.
As will be recognized, it is oftentimes desirable to view the location of an underlying wall stud or ceiling joist from different, remote perspectives around the room. For example, if a picture is to be hung on the wall or a light fixture hung from the ceiling, it is often desirable to get a visual “feel” from a distance as to how the picture or light fixture may look upon installation if positioned in a location wherein a hanger device may be interfaced directly to the underlying wall stud or ceiling joist. A small mark created by a scribe or a pencil is typically insufficient to provide a visual point of reference from any distance exceeding a few feet.
The present invention addresses this deficiency in prior art stud finders by providing a magnetic locating device which is specifically adapted to exert a force of magnetic attraction against a metallic object such as an underlying metal wall stud or ceiling joist which is sufficient to maintain the device in a prescribed position upon a support surface such as a wall or ceiling. Thus, in addition to being operative to assist in locating a metallic stud or joist embedded within a wall or ceiling behind at least one layer of drywall, plywood or other building material, the present locating device is further operative to provide an easily discernable visual reference point observable from virtually any location within the room. These, as well as other features of the present invention, will be discussed in more detail below.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a device for locating a metallic stud disposed within a wall. The device comprises an elongate housing which is preferably fabricated from a lightweight material, e.g., plastic, wood, aluminum, etc. The housing itself comprises a base portion which defines a generally planar contact surface, and a handle portion which is integrally connected to and extends along the base portion. The base portion and contact surface defined thereby each have a generally oval shape. The handle portion itself is generally cylindrically shaped with a circular cross-sectional configuration.
In addition to the housing, the locating device comprises at least one magnet which defines a generally planar attraction surface. The magnet is disposed within the base portion of the housing such that the attraction surface extends in generally parallel relation to the contact surface. More particularly, the magnet is preferably disposed within the base portion such that the attraction surface is substantially flush with (i.e., extends in generally co-planar relation to) the contact surface. The attraction surface of the magnet is rectangularly shaped, with the magnet itself having either a rectangular or a square cross-sectional configuration. As an alternative to a single magnet, a series of magnets may be disposed within the base portion of the housing in end-to-end fashion such that the magnets collectively define the attraction surface.
In the locating device of the present invention, the magnet and the housing are sized relative to each other such that the force of magnetic attraction between the magnet and the stud, when the device is oriented in a particular location upon the wall, is sufficient to maintain the device thereon without any external support. Thus, in addition to being operative to assist in the location of a metallic stud embedded within a wall behind at least one layer of drywall or other wall surface, the present device may also be used to provide a visual reference point observable from any location within the room. In order to provide this capability, the device is constructed to maximize the force of magnetic attraction exerted by the magnet, while minimizing overall weight so as to be maintainable upon the wall as a result of such force of magnetic attraction. In this regard, the contact surface defined by the base portion of the housing has a surface area of approximately 3.14 square inches, with the attraction surface of the magnet having a surface area of approximately 0.86 square inches. As such, the proportion between the surface areas of the contact and attraction surfaces is about 27 percent. Additionally, the magnet has an overall weight of approximately 0.94 ounces, with the housing itself having an overall weight of approximately 0.58 ounces. Thus, the total weight of the device is only about 1.52 ounces, with approximately 62 percent of such weight being taken up by the magnet.
The locating device of the present invention may optionally include a pair of slide pads which are attached to the contact surface of the base portion adjacent respective ones of the opposed ends thereof. The slide pads preferably have circular configurations, and are fabricated from a soft, pliable material such as felt. The inclusion of the slide pads assists in the movement of the device along the wall and the prevention of scratches or other abrasive damage thereto. It will be recognized that the locating device of the present invention may also be used to locate metallic objects such as nails. Additionally, the device may be used to locate
Bernsen Collin
Fazekas Craig
Snow Walter E.
Stetina Brunda Garred & Brucker
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