Patent Application
20050139739
The present invention relates to first structures each comprising a permanent magnets a magnet surface adapted to be positioned along a surface of a second structure comprising a layers of ferrous or ferromagnetic material so that one structures can be supported on the other structure by magnetic attraction, which first structure includes a layer of material that restricts relative movement between the first and second structures in the plane of their adjacent surfaces.
Many structures are known that each comprise at least one permanent magnet having a magnet surface adapted to be positioned along surfaces of structures comprising layers of ferrous or ferromagnetic material so that one of the structures can be supported on the other structure by magnetic attraction. Examples of such structures including a permanent magnet that has a planar surface intended to be supported by a planar surface of a structure including a layer of ferrous or ferromagnetic material are signs (which may bear pictures, sayings, memorabilia, advertising, etc.), hooks, spring clips, containers, or organizers which may be supported along refrigerators, metal furniture or cabinets, metal encased instruments, or the like. One example of such a structure including the permanent magnet which is intended to support the structure including the layer of ferrous or ferromagnetic material is described in U.S. Pat. No. 5,992,807 (Tarulli). In that structure a magnet permanently secured to the dashboard of a vehicle is adapted to removably retain a cell phone along a vertical surface of the magnet due to the magnetic attraction between the magnet and metal parts of the cell phone. Magnetic attraction between such structures provides instant attachment of the structures and good resistance to separation of the structures by pulling one from the other in a direction normal to their planar surfaces, however, it has limited ability to restrict slippage of the planar surfaces of the structures relative to each other. Thus when the planar surfaces of the structures are generally vertical the weight of the supported structure will often cause it to slide along the planar surface of the supporting structure, particularly when the structures are exposed to vibration, shock, or centrifugal forces. U.S. Pat. No. 5,992,807 describes providing “a thin layer of rubber or other suitable material” over the surface of the magnet that “provides a frictional resistance which is supplementary to the magnetic and prevents the cell phone from slipping down”, but provides no specifics concerning the type of rubber or other material to be used, or their effectiveness in preventing such slipping down.
Like the prior art described above, the present invention provides a first structure comprising a permanent magnet having a magnet surface adapted to be positioned along a surface of a second structure comprising a layer of ferrous or ferromagnetic material so that one of the structures can be supported on the other structure by magnetic attraction. The present invention is significantly improved from those prior art structures, however, in that the first structure further comprises a layer of removable pressure sensitive adhesive having a surface parallel with the magnet surface that is positioned to releasably adhere to the surface of the second structure and thereby significantly restrict slipping of the surfaces of the first and second structures relative to each other. While the adhesion of the layer of removable pressure sensitive adhesive to the planar surface will provide a high force in shear to restrict such slipping, it does not significantly increase the force required to separate the structure from the second structure, which separation is typically caused by manually pulling and/or pealing the supported structure away. This combination of magnetic attraction provided by the magnet to retain engagement of the structures against pulling and/or pealing forces and adhesion of the layer of removable adhesive that retains the relative positions of the structures against shear forces acting in the plane of the engaged surfaces allows the supporting structure to support a supported structure of significantly greater weight in a fixed position than could be supported if the layer of removable adhesive were not present, or if that layer or removable adhesive were replaced by a layer of non-adhesive material such as a layer of “rubber or similar material” as is described in U.S. Pat. No. 5,992,807.
The layer of removable pressure sensitive adhesive can extend over the planer magnet surface, or can be in a layer having a surface coplanar with the planer magnet surface which, for example, could extend around that magnet surface or be positioned on a side of that planer magnet surface where it will be biased into engagement with the planar surface of the second structure by torsional forces caused in the first structure resulting from the weight of the supported structure.
By removable pressure sensitive adhesive we mean to include the micro-structured relatively low tack and low adhesion type of removable and repositionable pressure sensitive adhesive available from 3M company, St. Paul, Minn. under the trademark “Post-it” (e.g., the removable and repositionable adhesive layer on No. 9416 “Post-it”0 brand transfer tape commercially available from 3M Company, St. Paul, Minn.), and any other relatively low tack and low adhesion removable and repositionable pressure sensitive adhesive that will adhere to most surfaces, but can be pealed away without leaving a residue and can then again be adhered to a surface, particularly including such adhesives which are micro-structured.
By perminant magnet we mean to include the type of flexible or molded permanent magnets sold under the trademark “PLASTIFORM” by the Plastiform division of Arnold Magnetics, Norfolk, Nebr.), and other perminant magnets that may have other structures such as all metal structures.
The present invention will be further described with reference to the accompanying drawing wherein like reference numerals refer to like parts in the several views, and wherein:
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A test was performed to determine the ability of a first structure or hook assembly 10 of the type described above to support weight along a vertically disposed surface of a second structure, compared to a similar hook assembly supported on that same vertically disposed surface only by a magnet (called a “magnet only” hook assembly herein), or only by a layer of removable pressure sensitive adhesive (called an “adhesive only” hook assembly herein). Three identical support members 12 of the type described above were used, each having a rectangular planer surface 13 that was 0.63 inch or 1.6 cm wide and 2 inches or 5.08 cm high. A flexible permanent magnet 14 of the type sold under the trademark “PLASTIFORM” by the Plastiform division of Arnold Magnetics, Norfolk, Nebr., about 0.06 inch or 0.15 cm thick and having the same peripheral dimensions as the surface 13 was adhered on the surface 13 of a first one of the support members 12. Over the surface of that magnet opposite the surface 13 was adhered a layer 20 of removable pressure sensitive adhesive (i.e., that layer 20 being provided by No. 9416 “Post-it” brand transfer tape commercially available from 3M Company, St. Paul, Minn., which included a support layer between a layer of strong or permanent pressure sensitive adhesive that was adhered to the magnet and the layer 20 of removable pressure sensitive adhesive), thereby forming a test hook assembly 10 having the structure described above. A magnet identical to the magnet 14 used in the test hook assembly 10 was adhered on the surface 13 of a second one of the support members 12 to form the “magnet only” hook assembly. A layer 20 of removable pressure sensitive adhesive formed of No. 9416 “Post-it” brand transfer tape and having the same peripheral dimensions as the surface 13 was adhered on the surface 13 of a third one of the support members 12 to form the “adhesive only” hook assembly. The three test hook assemblies were attached to the vertically disposed surface of a painted steel cabinet and increasing numbers of ½ pound weights were hung on the test hook assemblies until they began to slide down or separated from the vertically disposed surface. The “magnet only” hook assembly could only support one ½ pound weight and slid down the vertical surface when the second ½ pound weight was added. The “adhesive only” hook assembly could only support one ½ pound weight and separated from the vertical surface when the second ½ pound weight was added. The test hook assembly 10 having the structure described above supported four ½ pound weights or 2 pound before sliding, which was significantly more than the total amount of weight supported by the other two test hook assemblies. The test hook assembly 10 was found to be easily manually removed from and repositioned on the vertically disposed surface.
Another test was done with a product called a “Nifty Products Magnetic Locker Box” which is commercially available from Carolina Pad Company, Charlotte, N.C., and is a plastic rectangular container adapted to hold items that has a permanent magnet with a planar surface along a rear wall of the container by which the container can be magnetically attached to a vertical metal wall, such as the metal wall of a refrigerator, school locker, or office cabinet. The “Locker Box” was magnetically attached to the vertical painted metal wall of an office cabinet. A first ½ pound weight placed in the “Locker Box” did not cause it to move; however, when a second ½ pound weight was placed in the “Locker Box” it would slip along the wall and sometimes drop away from the wall. A strip of ¾ inch wide No. 9416 “Post-it” brand transfer tape commercially available from 3M Company, St. Paul, Minn., was then adhered across the bottom portion of the planer surface of the magnet, and the “Locker Box” was magnetically and adhesively attached to the same vertical metal wall. The “locker Box” could then support eight ½ pound weights (i.e., a total of 4 pounds), and could still be easily manually removed from and repositioned along the vertical wall.
Both tests described above were preformed during the first adhesion of the layers of repositionable adhesive to the vertical wall or surface. It was found that each removal and repositioning of those layers of repositionable adhesive along vertical surfaces decreased their effectiveness to help slipping of the perminant magnets along those surfaces, presumably because of increased surface contamination of the layers of repositionable adhesive.
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The present invention has now been described with reference to several embodiments and modifications thereof. It will be apparent to those skilled in the art that many changes can be made in the embodiments described above without departing from the scope of the present invention. For example, the hook-like structure 22, 42, or 62 on the support member 12, 32, or 52 of the first structure 10, 30, or 50 described above could be replaced by other means for engaging a third structure or object such as a spring clip or clamp, a pin, a cup-like structure or container, or an organizer; and/or the support members 12, 32, or 52 could have graphics (i.e., pictures, sayings, memorabilia, advertising, etc.) on their surfaces opposite the magnet 14, 34, or 54. The hook-like structure 22, 42, or 62 on the support member 12, 32, or 52 of the first structure 10, 30, or 50 described above could be replaced by other objects that need support such as sensors for instruments, novelty gadgets, shelves, electrical termination boxes, light fixtures, and radio antennas and other temporary articles mounted on automobiles, trucks and railroad cars. Release liners could be provided over the exposed surfaces of the layers of removable pressure sensitive adhesive on the structures described above to restrict contamination of those adhesive surfaces prior to use. Thus, the scope of the present invention should not be limited to the structures described in this application, but only by the structures described by the language of the claims and the equivalents thereof.
