WO2010078299A1

WO2010078299A1 - Magnetic array for securing an object to a ferromagnetic surface

Info

Publication number: WO2010078299A1
Application number: PCT/US2009/069650
Authority: WO
Inventors: Christopher M. Cacioppo; Hector Padilla
Original assignee: Sanford L.P.
Priority date: 2008-12-30
Filing date: 2009-12-29
Publication date: 2010-07-08

Abstract

A magnetic array for attaching an object (14) to a ferromagnetic surface includes a plurality of magnets arranged in a matrix (20), the plurality of magnets being attached to one surface (22) of the object. Each magnet (20a) in the plurality of magnets has an opposite polar orientation from a magnet immediately adjacent (20b) in the matrix along a row or a column of the matrix. The plurality of magnets produces more magnetic holding force than that of a single magnet of comparable size or mass. The magnetic field of the plurality of magnets is also more closely bound to a surface of the plurality of magnets, thus the magnetic field decays more quickly moving away from the matrix than the magnetic field of a single magnet of comparable size or mass.

Description

MAGNETIC ARRAY FOR SECURING AN OBJECT

TO A FERROMAGNETIC SURFACE

BACKGROUND

Field of the Disclosure

[0001] The disclosure generally relates to magnetic arrays for attaching objects to a surface and, more particularly, to magnetic arrays for attaching objects to a ferromagnetic writing surface, such as the writing surface of a whiteboard.

Related Technology

[0002] Existing technologies for capturing and storing handwritten notes include digitized writing surfaces such as electronic whiteboards. Such electronic whiteboards typically capture handwriting by either photocopying the writing surface, or by using the writing surface itself as an input device, such as an electronic template. These whiteboards may be touch sensitive or responsive to light or laser pens such that the writing surface itself detects the position of the writing instrument. Thus, known electronic whiteboards tend to be large, cumbersome, expensive and immobile.

[0003] To overcome the deficiencies of the whiteboards discussed above, new detection systems have been developed. One such system is disclosed in U.S. Patent No. 7,109,979, which is hereby incorporated by reference. U.S. Patent No. 7,109,979 discloses a system in which the location of a writing instrument is detected by a detector assembly using ultrasound and infrared light waves. The locations of the writing instrument are then transmitted to a computer and uploaded into a graphics program to produce a representation of the handwriting on the whiteboard on an electronic display. An advantage of such a system is that it is portable and attachable to any typical whiteboard. Thus, one detection system may be moved from one whiteboard to another, thereby reducing acquisition costs and improving the utilization rate of the detection system. For example, such a system may be moved from a classroom that is scheduled to be empty for a certain period of time, to another classroom that is scheduled to be occupied for the same period of time. Such detection systems may be removably attached to the whiteboard by conventional means, such as clamps, suction cups, hook and loop fasteners, two sided tape, refreshable contact cement, or a magnet. However, such conventional attachment mechanisms have drawbacks. Mechanical attachment mechanisms such as suction cups and hook and loop fasteners tend to wear out over time and loose their attachment ability. Typical adhesive type fasteners, such as two sided tape and refreshable contact cement tend to loose their adhesive properties over time. A Magnet of sufficient size/mass to attach the detection device to the whiteboard, white tending to maintain its attachment ability over time, is generally heavy and expensive.

SUMMARY OF THE DISCLOSURE

[0004] A magnetic array for attaching an object to a ferromagnetic surface includes a plurality of magnets arranged in a matrix, the plurality of magnets being attached to one surface of the object. Each magnet in the matrix having an opposite polar orientation from an immediately adjacent magnet in the matrix along a row or a column of the matrix. The magnetic array produces more magnetic holding force than the magnetic holding force of a single magnet of comparable size and strength. The magnetic fields of each of the magnets in the matrix are more closely bound to a surface of the matrix than the magnetic filed of a single magnet of comparable size and strength, thus the magnetic fields of the magnets in the array decay more quickly moving away from the matrix than the magnetic field of a single magnet of comparable size or strength. As a result, magnetic attraction to the ferromagnetic surface generated by the array only becomes significant when the array is placed very close to the ferromagnetic surface. An added benefit of the magnetic array is that a plurality of smaller magnets is generally lighter in weight and less expensive than a single magnet of comparable magnetic field strength.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005 J Objects, features, and advantages of the present disclosure will become apparent upon reading the following description in conjunction with the drawing figures, in which:

[0006J FIG. l is a plan view of a system that captures writing on a whiteboard; [0007] FIG. 2 is a bottom view of a detecting device of the system of FIG. 1 ;

[0008] FIG. 3 A is a close up perspective view of one embodiment of the magnetic array of FIG. 2;

[0009] FIG. 3B is a plan view of a second embodiment of a magnetic array; and

[0010] FIG. 4 is an exploded perspective view of a charging tray for storing and recharging a pen of the system of FIG. 1.

DETAILED DESCRIPTION

[0011] As shown in FIG. 1, electronic whiteboards typically include a writing surface or board 10, and a writing instrument 12, such as a dry erase marker or a water soluble marker. Additionally, some electronic whiteboards may include a detection device 14 for transmitting handwriting on the board 10 to a computer, and/or a charging tray (See FlG. 4). The detection device 14 and/or the charging tray may be removably or permanently attached to the board 10, The detection device 14 may detect coordinates of the writing instrument 12 by, for example, triangulation using sound and light waves, as disclosed in U.S. Patent No. 7,109,979. Such detection devices 14 are not significantly affected by magnetic fields. Because most whiteboards are ceramic (e.g., porcelain) coated steel sheets, the detection device 14 may be magnetically attached to the board 10. An advantage of magnetically attaching the detecting device 14 to the board 10 is that the detecting device remains removable from the board 10 and thus transportable to other boards 10. In this way, a single detection device 14 may be used on multiple boards 10, saving capital costs.

[0012] Instead of using a single magnet to removably attach the detecting device 10 to the board 10, the inventors have discovered that an array or matrix of smaller magnets alternating in polar orientation within the array or matrix is much more efficient and effective in removably mounting the detecting device 14 to the board 10. In addition to whiteboards, the disclosed magnetic array may be used to mount virtually any object to virtually any ferromagnetic surface. For example, the disclosed magnetic array may be used to removably mount chalk to a blackboard, a marker to a dry erase board, a radio frequency transmitter to a vehicle, etc.

[0013] Turning now to FIG. 2, the detecting device 14 is shown with an array or matrix 20 of small magnets mounted in a bottom surface 22 of the detecting device. The matrix 20 of magnets may be mounted in a cavity 24 in the bottom surface 22 of the detecting device 14. Moreover, the cavity 24 and the matrix 20 may be covered with a lid (not shown) that may include a high friction coating or material. Alternatively the high friction coating or material may be provided directly on the matrix of magnets. The high friction coating or material may inhibit movement of the detecting device 14 in a direction parallel to the surface of the board 10 by producing friction between the detecting device 14 and the board 10, thus preventing accidental dislodgement of the detecting device 14. Alternately, an adhesive, such as double sided tape, may be used as a supplemental securement means to prevent accidental dislodgement of the detection device 14. Often such detecting devices 14 need a reference point, such as the upper left hand corner of the board, from which coordinates of the writing instrument 12 may be calculated. Thus, once the detection device 14 is properly placed on the board 10, it is desirable to have the detection device 14 resistant to accidental movement. [0014] The matrix 20 shown in FIG. 2 includes 16 small magnets alternating in polar orientation. For example, in the matrix 20 shown in FIG. 2, the magnet 20a in the upper right hand corner of the matrix 20 is oriented with the north pole facing outward, away from the bottom surface 22. The magnet 20b immediately to the right of the magnet 20a is oriented in an opposite manner having its south pole facing outward, away from the bottom surface 22. The remaining magnets in the matrix 20 continue to alternate polar orientations throughout the matrix 20 so that any particular magnet's polar orientation is opposite to the polar orientation of an immediately adjacent magnet along rows and columns of the matrix 20.

[0015] FIGS. 3 A and 3B show two different embodiments of magnetic matrices that may be used in the mounting assembly. However, those skilled in the art will realize that virtually any size or type of matrix is possible given a particular object. For example, matrices constructed in accordance with the teachings of the disclosure may range in size from 2 x 2 to 10 x 10, or larger. Moreover, matrices need not be symmetric with respect to both rows and columns of the matrix. For example, a 1 x 2 matrix to a 1 x 10 matrix or more may be used.

[0016] FIG. 3 A shows the matrix 20 of FIG. 2 in a perspective view. The matrix 20 includes 16 separate square-shaped magnets 20a having alternating polar orientations as discussed above. FIG. 3B shows an alternate matrix 20 having 4 rectangular-shaped magnets 20a having alternating polar orientations. The inventors have discovered that a matrix 20 of smaller magnets is superior to a single larger magnet of comparable size/mass in a number of ways. Without being bound by theory, it is believed that the overall aggregate magnetic field strength of the matrix 20 is stronger than a comparable single magnet because magnetic field lines are bent between multiple poles (e.g., a single north pole forms a magnetic field with each adjacent south pole) of the magnets in the matrix 20. Moreover, it is believed that the overall aggregate magnetic field of the matrix 20 dissipates more rapidly moving away from the matrix 20, at least in part because of the multiple magnetic field lines between magnetic poles. This means that the overall aggregate magnetic field of the matrix 20 is more focused and stronger near a surface of the matrix 20 than that of a single larger magnet of comparable magnetic strength. This particular characteristic of the matrix 20 means that the matrix 20 will not be significantly attracted to a ferromagnetic surface until the matrix 20 is very close to the surface. Therefore, the object having the matrix 20 is easier to control during removal of the object from the board 10 or attachment of the object to the board 10. Additionally, the more focused overall aggregate magnetic field results in less interference with detection systems that are magnetically sensitive. [0017] The inventors conducted a series of experiments to determine the effects of various magnet thicknesses and numbers of magnets in a matrix. The results are summarized below in Table 1 :

TABLE 1

[0018] Neodymium-iron-boron magnets were used in compiling the results summarized in Table 1. In general, the matrices having smaller individual magnets and more total magnets seemed to produce more magnetic holding force when the matrix is disposed on a ferromagnetic surface. For example, a four magnet matrix produces roughly 100% more magnetic force when disposed on a ferromagnetic surface than a single magnet of the same size/mass, and a sixteen magnet matrix appears to produce roughly 40% more magnetic holding force when disposed on a ferromagnetic surface than a four magnet matrix of similar size/mass.

[0019] FIG. 4 shows an exploded perspective view of a charging tray 40. The charging tray 40 includes a housing having a contact surface 42 along which the charging tray is attached to the board 10 of FIG. 1. The contact surface 42 has a cavity 44 into which the matrix 20 of magnets is disposed. The matrix 20 and cavity 44 may be closed with a cover 46 made of plastic or other suitable material. The cover 46 may include a high friction coating 48 to aid in maintaining position of the charging tray 40 when the charging tray 40 is mounted to the board 10.

[0020] While rare earth magnets are generally disclosed herein, virtually any type of magnet could be used to produce the magnetic array. For example, other suitable types of magnets include, but are not limited to, Samarium Cobalt (SmCo), Alnieo, and Ceramic or Ferrite magnets. Moreover, permanent magnets, temporary magnets, or electromagnets may be used to produce the magnetic array.

[0021] The magnetic array may be used on virtually any device that is to be removably attached to a ferromagnetic writing surface. For example, as will be appreciated by one skilled in the art, the magnetic array as described above may be used to attach various objects to writing surfaces as electronic whiteboards, chalkboards, overhead projectors, and the like. Such objects may include position detection devices, charging trays, writing instalments (e.g., pens, markers or brushes), and the like.

[0022] Although certain magnetic arrays have been described herein in accordance with the teachings of the present disclosure, the scope of coverage of this patent is not limited thereto. On the contrary, while the invention has been shown and described in connection with various preferred embodiments, it is apparent that certain changes and modifications, in addition to those mentioned above, may be made. This patent covers all embodiments of the teachings of the disclosure that fairly fall within the scope of permissible equivalents. Many variations of the invention may also be used without departing from the principles outlined above. Accordingly, it is the intention to protect all variations and modifications that may occur to one of ordinary skill in the art.

Claims

What Is Claimed Is:

1. A method of creating an object that is removably attachable to a ferromagnetic surface, comprising: providing a plurality of dipole magnets; arranging the plurality of dipole magnets in a matrix; and attaching the matrix of magnets to the object; wherein adjacent magnets in the matrix are oriented in opposite polar directions so that a north pole of one magnet in the matrix is adjacent south poles of surrounding magnets along a column or a row of the matrix.

2. The method of claim 1 , wherein the plurality of magnets comprises at least four magnets.

3. The method of claim 2, wherein the matrix is a 2 x 2 matrix.

4. The method of claim 1, wherein the plurality of magnets includes at least sixteen magnets.

5. The method of claim 4, wherein the matrix is a 4 x 4 matrix.

6. The method of claim 1, wherein at least one of the magnets in the plurality of magnets is a rare earth magnet.

7. The method of claim 6, wherein the at least one magnet is a neodyminu-iron-boron magnet.

8. The method of claim 1, wherein the object is a position sensing device.

9. The method of claim 8, wherein the position sensing device is not significantly affected by magnetic fields.

10. The method of claim 1, wherein the object is a charging tray.

11. The method of claim 1 , wherein the ferromagnetic surface is a writing surface of a whiteboard.

12. The method of claim 1, wherein a surface of the matrix is at least partially covered with a high friction covering.

13. The method of claim 1, wherein the magnetic force generated by the matrix is strong enough to create a frictional force between the object and the ferromagnetic surface sufficient to hold the object stationary on the ferromagnetic surface when the ferromagnetic surface is arranged in a vertical orientation.

14. The method of claim 1, wherein at least one of the magnets in the plurality of magnets has a square shape.

15. The method of claim 1, wherein the object further comprises an adhesive on at least part of an outside surface of the object.

16. An object adapted to be removably attachable to a ferromagnetic writing surface, the object comprising: a housing having a cavity; and a plurality of magnets disposed in the cavity, the plurality of magnets being arranged in a matrix wherein the magnets alternate in polar orientation along a row and/or a column of the matrix.

17. The object of claim 16, wherein the plurality of magnets is arranged in a 4 x 4 matrix.

18. The object of claim 16, wherein at least a portion of the cavity is covered by a high friction material.

19. The object of claim 16, wherein at least one of the magnets is square shaped.

20. The object of claim 16, wherein the housing comprises an adhesive on at least a part of an outside surface of the object.

21. A detecting device for attaching to a vertically oriented ferromagnetic writing surface of a whiteboard, the detecting device comprising, a housing having an upper surface and a lower surface, a cavity in the lower surface; a matrix of magnets disposed in the cavity, each magnet in the matrix of magnets being oriented in an opposite direction from adjacent magnets in the matrix of magnets along a row or a column of the matrix.

22. The detecting device of claim 21, wherein the detecting device is arranged to detect the position of a writing instrument on the ferromagnetic writing surface by using triangulation of light and sound waves.

23. The detecting device of claim 22, wherein the matrix includes a supplemental securement device.

24. The detecting device of claim 23, wherein the supplemental securement device is a high friction coating.

25. The detecting device of claim 23, wherein the supplemental securement device is a double sided adhesive tape.

26. The detecting device of claim 21 , further comprising a cover for holding the matrix of magnets in the cavity, the cover including a high friction material.

27. A tray for attaching to a ferromagnetic writing surface of a whiteboard, the tray comprising, a housing having a first surface for receiving instruments for using on the whiteboard and a second surface substantially perpendicular to the first surface; a cavity in the second surface; a matrix of magnets disposed in the cavity, each magnet in the matrix of magnets being oriented in an opposite direction from adjacent magnets in the matrix of magnets along a row or a column of the matrix.

28. A magnetic array for attaching an object to a ferromagnetic surface, the magnetic array comprising: a plurality of magnets arranged in a matrix, each magnet in the matrix being oriented in an opposite polar direction from adjacent magnets in the matrix of magnets along at least one of a row or a column of the matrix.