Patent Application
20080030290
The following listed drawings depict only typical and preferred embodiments of the invention and are identified as follows:
Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The various exemplary embodiments provide a stylus for a visual display.
In the visual display, an image is formed by aligning flakes that can be either magnetic or magnetically permeable. The flakes are contained and mixed within a dispersion medium. Upon presentation of a magnetic field, the flakes orient along the flux lines of the magnetic field. Alignment of the flakes changes the translucency so that light may pass through the medium in the vicinity of the aligned flakes. Before alignment, the flakes are dispersed in the medium; and the flakes in effect scatter or block the light that is directed through the dispersion medium.
When a magnetic field is applied from a permanent magnet, for instance, such as one formed from a nickel alloy composition, an amorphous magnet of iron nickel boron composition, or other suitable magnetic material, magnetic particles or permeable, particles tend to be attracted to the magnetic field of the magnet and accumulate within the magnetic field. A magnetic field is sometimes depicted by illustrating a plurality of lines like lines 24 and 26 in
By dispersing the permeable particles in a viscous liquid, the viscosity of the liquid slows down the magnetic alignment of the particles but also holds the magnetic particles in the magnetically induced alignment so the image remains stable after formation. Of course the viscosity of the liquid containing the permeable or magnetic flakes must also be sufficiently low that permeable or magnetic particles may move through the liquid toward a magnetic field and or to be in alignment with he lines of flux of the magnetic field.
It has been observed that the overall geometry of each of these permeable particles exhibiting this attraction phenomenon which travel through the viscous liquid to the magnetic field have a geometry which is generally spherical. In fact, it has been observed that as these permeable particles become more spherical in shape, the travel of the particles through the viscous liquid to the applied magnetic field occurs with greater frequency and becomes more apparent. However, as the configuration of the permeable particles becomes less spherical and more flattened or flake-like, these particles tend to align along the flux lines of the magnetic field and not travel through the viscous liquid to the locus of the magnetic field, remaining relatively stationary. Thus, image in the visual display formed is dependent on the geometry of the permeable particles as well as on the nature of the magnet presented for forming the image.
One measure of the geometry of a particle is the ratio of a particle's length to width to height. For convenience, this ratio is defined as the aspect ratio of the particle. Determination of the aspect ratio of a magnetic particle provides a measurement in absolute terms of the geometry of a magnetic particle. Calculation of the aspect ratio thus provides a standard for selecting metallic particles for use in the visual display which have the desired alignment characteristics along the flux lines of the applied magnetic field.
For a spherical particle, the aspect ratio is 1:1:1, or unity. Particles with an aspect ratio approximating unity generally do not align along the flux lines of the magnetic field when contained in a viscous liquid, but exhibit the attraction and movement phenomenon as described above, traveling through the liquid and accumulating at the locus of the magnetic field.
In one example, commercially available metal particles such as Inco Nickel Powder Type 123 are used that have a particle size approximating four microns with the particles having a dendritic geometry. Due to the small, irregular size of the particles, however, it is difficult to determine which is the longest axis for determination of an aspect ratio of the particles. Nonetheless, these particular particles behave like spherical particles having an aspect ratio of unity when they are exposed to a magnetic field. In like manner, spherical nickel particles, such as those commercially available from Novamet, Inc., (Novamet 4SP), an eight-micron diameter sphere with an aspect ratio of unity, will travel through a dispersion medium when attracted to a magnetic field and not align along the flux lines of the magnetic field. (Commercially available ferrous powders, such as 325 mesh and 100 mesh by Hoeganaes, also exhibit the attraction phenomenon.)
When the aspect ratio of the particles varies from that of unity, the particles tend to line up with their longest axis in the direction of the flux lines of an applied magnetic field. This alignment provides a change in the light transmission through the visual display.
Permeable particles, including metallic and non-metallic particles having an aspect ratio greater than unity which exhibit the alignment phenomenon along the flux lines of an applied magnetic field, are hereinafter referred to as permeable flakes. Permeable flakes are thus defined as metallic particles exhibiting the alignment characteristics which provide the change in the light transmission characteristics of the dispersion medium. For instance, flakes that are 15 microns in length and width and 1 micron in height have an aspect ratio of 15:15:1. With an aspect ratio of 15:15:1, these flakes exhibit the alignment phenomenon along the flux lines of a magnetic field. Also, because of the induced magnetic field properties of the flakes after exposure to the magnetic field, the flakes exhibit both attraction and repulsion characteristics which assist in producing and maintaining flake alignment and resist translational movement of the flakes. The alignment of the flakes along the magnetic flux lines coupled with their attraction and repulsion properties relative to each other when aligned provide the desired change in light transmission characteristics in the dispersion medium.
Another example of a permeable flake exhibiting the aspect ratio phenomenon which provides the desired alignment properties are magnetic fine cylindrical fibers. For example, when seven-micron diameter nickel-coated graphite fibers are cut to 50-micron lengths, these fibers have an aspect ratio of 50:7:7 and exhibit the desired alignment characteristics within the dispersion medium during exposure to a magnetic field.
In the exemplary embodiment, complete alignment of the flakes will occur when the flakes are exposed to the magnetic field, assuming that each of the flakes has the proper geometry or aspect ratio to align itself with the flux lines of the magnetic field. However, differences in the aspect ratios between individual flakes may produce an incomplete alignment of each flake in the system when a magnetic field is introduced thereto. The alignment effect, however, is most pronounced as the average aspect ratio increases within a given population of magnetic flakes.
A population of permeable flakes with an aspect ratio having at least two of the height, length or width measurements, for example, of approximately about 5:1 or greater, or, more specifically, approximately about 10:1 or greater is to overcome most effects of varying flake size. Permeable flakes having aspect ratios in these ranges have been observed to provide the desired change in light transmission in the dispersion medium during flake alignment. However, in the event irregularly-shaped flakes are used (which prevent true measurement of absolute length, width or height), the measurements used to calculate the aspect ratio correspond to the longest linear measurement along the geometry of the flake, the other aspect ratio measurements taken perpendicular thereto.
The relative strength of a magnetic field is often depicted not by the number or density of flux lines but may also be shown by the thickness of the flux lines. Notably, magnetic field strength varies both according to the relative strength of the magnetic field and to the configuration of the magnet or magnetic field source. Therefore, the strength of the magnet and density of the flux lines is an important factor to consider in inducing the flake alignment phenomenon of the visual display.
The relative strength of the magnetic field as reflected by the density of the flux lines is not here depicted. Rather, the strength may be selected somewhat empirically to effect the formation of an image.
Referring to the drawings,
The dispersion medium 12 with the permeable flakes 14 is retained within a volume 15 defined by opposing surfaces 18 and 19. In one example, the surface 18 has or includes a transparent or translucent area which allows observation of the flake alignment phenomenon through and in the dispersion medium 12 as light 17 passes through surface 19 through a translucent or transparent section toward the surface 18 as will be discussed in detail below.
The magnet 10 is here shown to be cylindrical with an axis 11 oriented normal to the surface 18. While the magnet 10 is shown to be cylindrical, it may be in any suitable or desired shape. For purposes of this invention, the magnet 10 is preferably one in which the height or length 58 exceeds the diameter 59. Indeed, the preferred magnet 10 of the present invention will have a height or length 58 that is at least two times bigger than the diameter 59 and even more preferably at least five times the diameter 59. While there is no particular limit to the height or length 58, practical use would limit it to about one foot or there about.
An electro magnet or permanent magnet like magnet 10 are sometimes said to have a north pole and a south pole or alternately a positive pole 20 and a negative pole 22. The magnet 10 has a magnetic field 24 which is three-dimensional force field around its entire perimeter or circumference 13. The force field 24 is typical for permanent magnets with the field being stronger closer to the outer surface 15 and generally weaker the farther away 21 from the magnet 10 in any direction generally normal to the axis 21 or even along the axis 11. Of course the force field at the poles or positive end 20 and negative end 22 is also strong as is known for magnets having poles and more particularly for permanent magnets. The magnetic field 24 is here depicted in two dimensions by a plurality of flux lines 26 radiating or extending between the positive pole 20 and the negative pole 22. Given that the magnet 10 has a preselected magnetic strength, the magnet 10 may be placed at a distance 16 from the surface 18 that is selected so that the magnetic field 24 is so weak that it can be said to have no effect on the permeable flakes 14 dispersed in the medium 12.
Referring to
As stated hereinbefore the flakes 14 are permeable so they become magnetic in the presence of the magnetic field 24 of the magnet 10. In turn, each flake 14 in the presence of the magnetic field has a north pole and a south pole or a positive pole and a negative pole as indicated by the plus (+) and minus (−) signs 30 respectively Since it is well known that for two proximately positioned magnets, magnetic opposites attract (e.g., north and south poles) and magnetic likes (e.g., north pole and north pole) repel. The induced magnetic field in each of the flakes 14 is believed to be positive to negative as shown. With the induced magnetic field, the permeable flakes 14B-E align so that their positive (+) and negative (−) poles are attracted to each other and to the positive or negative pole of the magnet 10.
In the alignment zone 28, it can be seen that the flakes 14B near the pole 20 or close to the axis 11 tend to be oriented somewhat normal to the surface 18 and in general alignment with the axis 11. That is, the magnetic field 24 is at or less than angle 27. In turn, the aligned flakes 14C are closer to alignment with axis 11. With the thickness 29 of the volume 15 selected so that the magnetic field 24 extends through surface 19, it can be seen that the flakes 14C closest to the axis 11 (within the angle 27) are oriented to allow light 17 to pass through surface 19, through the medium 12, past aligned flakes 14C and through surface 18 to be visible. At the same time, the flakes 14D aligned in the magnetic field in a direction somewhat normal to axis 11 block or inhibit the light transmission to help define the image visible at the surface 18. Of course, the flakes 14E begin to align vertically as the magnetic field or lines of flux get closer to being generally parallel to the axis 11. Some additional light 17 may pass through the medium and create a short of halo or shadow of the image along the axis 11 between the aligned flakes 14D and the randomly dispersed flakes 14A that are outside the influence of the magnetic field 24. In turn, the perceived resolution of the perceived image is reduced and seen mare as a line that is not sharp and distinct. Thus one seeking to present letters or numbers is forced to present larger letters or numbers than if the lines were very sharp or with a high resolution.
From another perspective, it may be said that the light 17 transmission characteristics of the dispersion medium 12 in the alignment zone 28 is greater than in zones 29 and 36 on either side of zone 28. The magnetic field 24 imposes a somewhat V-shaped 33 orientation of the flakes 14E in outer zone 34 providing a “halo” effect along the edges of the alignment zone 28. The induced halo results in less resolution (larger lines) produced by the magnet 10. Similarly a V shaped orientation 35 is imposed on the flakes spaced somewhat from the axis 11 again contributing to a wider line with less resolution. At or beyond the outer zone 34, the flakes 14A remain essentially uninfluenced by the magnetic field and remain normally dispersed. It should also be noted that the angle of orientation 39 of the magnet 10 relative to the surface 18 may vary from about zero degrees to 90 degrees. As the angle 39 decreases from 90 degrees, the axis 11 crosses or intersects the surface 18 at an angle thereby modifying the location of the zones 28, 29, 34 and 36. As the angle 39 changes from 90 degrees to about zero degrees, it is believed that the alignment zones vary so that the resolution of the line or image created diminishes.
The alignment phenomenon, along with the number of influence zones of the permeable flakes 14, may vary depending upon the type and strength of magnet used as well as the geometry or shape of the magnet 10.
Inasmuch as smaller magnets are not as strong as large magnets and have not been found to have sufficient magnetic force field to induce the permeable flakes 14 to align and produce a useful image, only larger magnets 10 have been used in systems of this type and in turn only images having larger lines with more discernable halo's can be formed.
When these writing devices are used in a tablet form, the amount of text or other markings are limited to the size of the tablet and the thickness of the lines drawn on it. Small tablets provide better portability and storability. For example, in a multiplication layout on the tablet, previously there was only room to fit 10×10 rows and columns. It is more desirable to have a 12×12 arrangement to allow teachers to teach pupils 1 to 12 times tables. This has been impractical based on the size of a typical tablet having a volume 15 with a medium (e.g. a viscous liquid-type material) due to the thickness of the lines created by the available stylus. In addition, handwriting was hard to practice with thick lines. Smaller magnets were used to make thinner lines, but lines were not as visible or distinct because the magnetic field is weaker and in turn the quantity of permeable flakes 14 aligned is less.
In
The aperture or bore 60 is typically cylindrical in shape. The magnet 10 is typically formed to be cylindrical shape but it may also have facets or a plurality of sides to be triangular in cross section, elliptical in cross section, octagonal in cross section, or in some other suitable or desired cross section, all sized to snuggly receive the magnet 40. That is, the aperture 60 may be in any shape or combination of shapes sized to snuggly receive the magnet 10.
In
In the various exemplary embodiments, the point 48 can extend beyond the sleeve 44 by various heights 54 depending on the application and desired line thickness. For instance, the point 48 can extend beyond the sleeve 44 by a height 54 (
The bore 60 in the sleeve 44 forms a wall 67 that surrounds the magnet 40 and has a thickness 68 of about 0.5 mm. The sleeve 44 can be quite short (about 10 mm) in length 65 and sized to fit into another structure or housing to function as a pen, pencil or similar writing instrument. It may be sized in length 65 from about 5 centimeters to about 10 or more centimeters to accommodate a magnet 40 of suitable strength but which is in effect long and narrow.
As shown in
The sleeve 44 is made of ferromagnetic material, such as iron. Of course other ferromagnetic compositions may also be used. While the material is not magnetic, is permeable. It is believed that the ferromagnetic material directs or limits the width 41B of the flux lines 41A to make the magnetic field projected into the dispersion medium 12 with flakes 14 of a gel pad or the like. The sleeve 44 can be seal coated to prevent or resist corrosion, for example, a ceramic based coating can be applied to the surface of the sleeve 44. The coating provides a smoother surface on the writing end 50.
The width 56 of the magnet 40 can vary depending on the desired size of the visual image and more particularly the lines being formed by movement of the tip 58 over the surface 18. For instance, one size can simulate a typical line formed by a ball-point pen or pencil; while another size (slightly larger) can be sized to simulate a line formed by a felt-tip marker. In yet other embodiments, the magnet 40 and sleeve 44 can be sized so that the line formed on the surface 18 simulates a piece of chalk. Some examples of the various embodiments are shown in Table A, below.
The sleeve 44 is placed around the various magnets like magnet 40 to narrow the magnetic flux or field. Typically, the sleeve 44 which surrounds the magnet examples listed in Table A to form the tip 42 has a thickness of about 0.5 mm to about 1.5 mm. The sleeve 44 has a slanted surface 72 around the writing end 50 of the tip 42 that is positioned at an angle 73 relative to the tip surface 41 that varies from about 60 degrees to about 15 degrees with the edges 80 and 82 preferably rounded or tapered to provide a smooth feel as the tip 42 is moved across the surface 18. If the surface 72 is rounded to a radius, the radius can be approximately the same as the thickness 68 of the sleeve 44. For instance, if the thickness of the sleeve is about 0.6 mm, then the radius can be about 0.45 mm at the writing end 50. Of course the surface 72 may also be shaped into any desired arcuate (in cross section) form so that the tip may move more easily over the display surface.
The tip 42 can then be inserted into, formed in, or otherwise disposed in an end 72 of a pen or stylus 74 as illustrated in
The flux lines of the magnetic field 70 pass through the surface 18 of the dispersion medium 12, causing the permeable flakes 14 mixed within the dispersion medium 12 to orient themselves and align along the flux lines of the magnetic field 70, creating an image. The alignment of the permeable flakes causes an image to be created as a result of a change in the transmission of light through and into the dispersion medium 12. When the flux lines of the magnetic field 70 are introduced to the flakes 14 as depicted in
The magnetic field 70 of the magnet 40 acts upon the suspended permeable flakes 14 in an area adjacent the tip 42. Moving the tip 42 over the dispersion medium 12 causes the flakes 14 in an area adjacent to the surface 18 to be oriented from a random position to another position that is essentially vertical to or in alignment with the axis 41C of the magnet 40. To the observer, this re-orientation of flakes 14 produces an image and preferably a black image, in contrast to the metallic sheen observed on the remainder of the surface 18 because light does not transmit therethrough. Alternately, it should be understood that light may transmit through surface 18 through the dispersion medium 12 toward the surface 19 which has an interior color so that upon reflection of the light back out of and through the surface 18 so that the user perceives a desired color.
While the stylus and tip have been described with reference to the specific embodiments described, the descriptions are only illustrative and are not to be construed as limiting the invention. As such, the optimal dimensional relationships for the parts of the exemplary embodiment of the invention can be varied in size, materials, shape, configurations, form, function and manner of operation. The optimal dimensional relationships, use and assembly that are readily apparent to those skilled in the art and all equivalent relationships to the embodiments illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
