# US 4,398,893 A · Erasable magnetic diagramming panel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,893 A - Document ID: US4398893A - Status: Granted - Kind: A - Application number: 06/301,738 - Filed: 1981-09-14 - Granted: 1983-08-16 - Earliest claimed: 1981-09-14 - Assignees: Motion Marker Systems, Incorporated - Inventors: Paul J. Johns - Web page: https://patentgrep.com/patent/US4398893A ## CPC - G09B 29/00: Maps; Plans; Charts; Diagrams, e.g. route diagram (star maps G09B27/04; devices for holding or supporting maps A47B97/02; for computing purposes G06G1/14, G09B1/16; display boards G09F) - B43L 1/008: {with magnetic action} - G09B 1/08: by means of magnets - G09B 19/14: Traffic procedures, e.g. traffic regulations - G09B: EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS (devices for psychotechnics or for testing reaction times A61B5/16; games, sports, amusements A63; projectors, projector screens G03B) - B43L: ARTICLES FOR WRITING OR DRAWING UPON; {WRITING OR DRAWING AIDS;} ACCESSORIES FOR WRITING OR DRAWING (workshop equipment for marking-out work B25H7/00; teaching hand-writing or drawing G09B11/00) ## Abstract To permit easy changes in a diagram made over an overlay on a vertically-mountable panel, the panel includes a ferromagnetic backing material and a transparent nonmagnetic front panel spaced a predetermined distance from the back panel to receive movable magnetic symbol pieces with a fixed diagram between them. The size of the magnetic pieces and the spacing between the ferromagnetic back panel and the nonmagnetic front panel is such that the pieces may be lifted a slight distance from the back panel by moving a magnet that slides along the front panel and moved from place to place and yet, when the moving magnet is pulled free, the magnetic attraction to the ferromagnetic backing and the distances are such that the symbol is pulled back against the ferromagnetic back panel and is held in place against gravity. The transparent nonmagnetic front surface is flat, relatively firm and impermeable to moisture so that it may be marked upon and erased. ## Claims ### Claim 1 A panel for diagramming adapted for selective positioning in one of a substantially vertical and horizontal position comprising: a flat diagramming area adapted to serve as a symbol piece holding means for holding symbol piece means; means for mounting said flat diagramming area in a substantially vertical position; said flat diagramming area including first and second spaced-apart plates; said first plate being a rear plate including a ferromagnetic backing having ferromagnetic characteristics across its area; means for mounting a design sheet between said first and second plates; said second plate being transparent, whereby the design on said design sheet may be viewed from the front of said diagramming panel; spacer means for mounting said first and second plates at predetermined distance from each other; magnetic symbol piece moving means for moving symbols within said first and second plates by moving said symbol means across the surface of said first plate; said magnetic symbol piece moving means including a positioning magnet; magnetic symbol piece means movable in response to said magnetic moving means; said second plate being sufficiently smooth and flat to receive marks; one of said first plate and design sheets having a first surface and one of said design sheets and second plate having a second surface; said first and second surfaces facing each other and being spaced from each other; and the static coefficient of friction between the contacting surfaces of each symbol piece means and the symbol piece holder means multiplied by the square of the flux density linking the symbol piece means and the ferromagnetic backing multiplied by the area of the linkage by flux being at least equal to the weight of the symbol piece means. ### Claim 2 (depends on 1) A panel according to claim 1 in which the square of the flux density linking the positioning magnet and the symbol piece means multiplied by the area of the linking flux is greater than the square of the flux density linking the symbol piece means and the ferromagnetic backing. ### Claim 3 (depends on 2) A panel according to claim 2 in which the static coefficient of friction between the contacting surfaces of the symbol piece means and the second surface multiplied by the square of the flux density linking the symbol piece and the positioning magnet multiplied by the area of the linking flux is at least equal to the weight of the symbol piece means added to the flux density linking the ferromagnetic backing and the symbol piece means multiplied by the area of this linking flux. ### Claim 4 (depends on 3) A panel according to claim 3 in which the square of the linking flux density multiplied by the area between the symbol piece means and the positioning magnet is sufficiently great to compensate for the forces of inertia, the static coefficient of friction between the contacting surfaces of the symbol piece means and second surface multiplied by the square of the linking flux density multiplied by the area between the symbol piece means and the positioning magnet and the weight of the symbol piece means. ### Claim 5 (depends on 4) A panel according to claim 4 in which the dynamic coefficient of friction between the contacting surfaces multiplied by the difference between two quantities, the first of which is the square of the flux density linking the symbol piece and the positioning magnet multiplied by the area of the linking flux and the second of which is the square of the flux density linking the symbol piece multiplied by its area is at least sufficiently large to compensate for momentum, and the weight of the symbol marker to enable the symbol piece means to fall into place when the positioning magnet is removed. ### Claim 6 (depends on 5) A panel according to claim 5 in which the square of the flux density linking the symbol piece means when it is against the second surface multiplied by the area of the linking flux is less than 192 multiplied by the separation, multiplied by the weight of the symbol piece. ### Claim 7 Apparatus for diagramming adapted for selective positioning in one of a substantially vertical and horizontal position comprising: a flat diagramming area; means for mounting said flat diagramming area in a substantially vertical position; said flat diagramming area including first and second spaced-apart plates; said first plate being a rear plate having ferromagnetic characteristics across its area; means for mounting a design sheet between said first and second plates; said second plate being transparent, whereby the design on said design sheet may be viewed from the front of said diagramming panel; spacer means for mounting said first and second plates at predetermined distance from each other; magnetic symbol moving means for moving symbols within said first and second plates by moving said symbol means across the surface of said first plate; magnetic symbol means movable in response to said magnetic moving means; and said second plate being sufficiently smooth and flat to receive marks. ### Claim 8 (depends on 7) Apparatus according to claim 7 in which: the height of said magnetic symbol means is slightly less than the space between said first and second plates; and said magnetic members have sufficient magnetic strength so that they may be slightly lifted from said first plate by said magnetic symbol moving means and moved from said second plate back to said first plate to be held therein when said panel is in a vertical position. ### Claim 9 (depends on 8) Apparatus according to claim 8 in which said magnetic symbol moving means includes means for placing a visible mark on said second plate as said magnetic symbol moving means is moved across the outer surface of said second plate. ### Claim 10 (depends on 9) Apparatus according to claim 9 in which said magnetic symbol moving means includes first and second magnets. ### Claim 11 (depends on 10) Apparatus according to claim 10 further including an elongated handle fastened to said magnetic symbol moving means, whereby said magnetic symbol means may be moved from a distance. ### Claim 12 (depends on 11) Apparatus according to claim 11 in which said first plate includes a flat plastic plate with relatively thin ferromagnetic material across one surface. ### Claim 13 (depends on 12) Apparatus according to claim 12 in which said first and second plates are spaced from each other by plastic walls along three edges thereof, whereby an opening is left at one edge to receive said magnetic symbol means. ### Claim 14 (depends on 13) Apparatus according to claim 13 in which said magnetic symbol means include ceramic magnets. ### Claim 15 (depends on 14) Apparatus according to claim 14 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 16 (depends on 13) Apparatus according to claim 13 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 17 (depends on 7) Apparatus according to claim 7 in which said magnetic symbol moving means includes a means for placing a visible mark on said second plate as said magnetic symbol moving means is moved across the outer surface of said second plate. ### Claim 18 (depends on 17) Apparatus according to claim 17 in which said magnetic symbol moving means includes first and second magnets. ### Claim 19 (depends on 18) Apparatus according to claim 18 further including an elongated handle fastened to said magnetic symbol moving means, whereby said magnetic symbol means may be moved from a distance. ### Claim 20 (depends on 19) Apparatus according to claim 19 in which said first plate includes a flat plastic plate with relatively thin ferromagnetic material across one surface. ### Claim 21 (depends on 20) Apparatus according to claim 20 in which said first and second plates are spaced from each other by plastic walls along three edges thereof, whereby an opening is left at one edge to receive said magnetic symbol means. ### Claim 22 (depends on 21) Apparatus according to claim 21 in which said magnetic symbol means include ceramic magnets. ### Claim 23 (depends on 22) Apparatus according to claim 22 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 24 (depends on 22) Apparatus according to claim 22 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 25 (depends on 7) Apparatus according to claim 7 in which said magnetic mover includes first and second magnets. ### Claim 26 (depends on 25) Apparatus according to claim 25 further including an elongated handle fastened to said magnet symbol moving means, whereby said magnetic symbol means may be moved from a distance. ### Claim 27 (depends on 26) Apparatus according to claim 26 in which said first plate includes a flat plastic plate with relatively thin ferromagnetic material across one surface. ### Claim 28 (depends on 27) Apparatus according to claim 27 in which said first and second plates are spaced from each other by plastic walls along three edges thereof, whereby an opening is left at one edge to receive said magnetic symbol moving means. ### Claim 29 (depends on 28) Apparatus according to claim 28 in which said magnetic symbol moving means include ceramic magnets. ### Claim 30 (depends on 21) Apparatus according to claim 21 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 31 (depends on 29) Apparatus according to claim 29 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 32 (depends on 7) Apparatus according to claim 7 further including an elongated handle fastened to said magnetic symbol moving means, whereby said magnetic symbol means may be moved from a distance. ### Claim 33 (depends on 32) Apparatus according to claim 32 in which said first plate includes a flat plastic plate with relatively thin ferromagnetic material across one surface. ### Claim 34 (depends on 33) Apparatus according to claim 33 in which said first and second plates are spaced from each other by plastic walls along three edges thereof, whereby an opening is left at one edge to receive said magnetic symbol means. ### Claim 35 (depends on 34) Apparatus according to claim 34 in which said magnetic symbol means include ceramic magnets. ### Claim 36 (depends on 35) Apparatus according to claim 35 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 37 (depends on 35) Apparatus according to claim 35 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 38 (depends on 7) Apparatus according to claim 7 in which said first member includes a flat plastic plate with relatively thin ferromagnetic material across one surface. ### Claim 39 (depends on 38) Apparatus according to claim 38 in which said first and second plates are spaced from each other by plastic walls along three edges thereof, whereby an opening is left at one edge to receive said magnetic symbol means. ### Claim 40 (depends on 39) Apparatus according to claim 39 in which said magnetic symbol means include ceramic magnets. ### Claim 41 (depends on 40) Apparatus according to claim 40 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 42 (depends on 40) Apparatus according to claim 40 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 43 (depends on 7) Apparatus according to claim 7 in which said first and second plates are spaced from each other by plastic walls along three edges thereof, whereby an opening is left at one edge to receive said magnetic symbol means. ### Claim 44 (depends on 43) Apparatus according to claim 43 in which said magnetic symbol means include ceramic magnets. ### Claim 45 (depends on 44) Apparatus according to claim 44 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 46 (depends on 45) Apparatus according to claim 45 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 47 (depends on 7) Apparatus according to claim 7 in which said magnetic symbol means include ceramic magnets. ### Claim 48 (depends on 47) Apparatus according to claim 47 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 49 (depends on 47) Apparatus according to claim 47 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 50 (depends on 7) Apparatus according to claim 7 in which said second plate is made of a nonconductive diamagnetic material. ### Claim 51 (depends on 7) Apparatus according to claim 7 in which said second plate is made of a nonconductive paramagnetic material. ### Claim 52 A magnetic mounting system comprising: a compartment having first and second inner walls defining a predetermined width; magnetic symbol means having a predetermined weight and height; first magnetic means for holding said magnetic symbol means against said first inner wall when said wall is vertical; second magnetic means for selectively pulling said magnetic symbol means against said second wall and moving it along said wall; and said first magnetic means including means for pulling said magnetic symbol means back from said second wall against said first wall and holding it against said first wall when said second magnet means is released. ### Claim 53 (depends on 52) A magnetic mounting system according to claim 52 in which: one side of said compartment is transparent; said magnetic symbol means carries a symbol; and said second magnet means includes a manual control, whereby said magnetic mounting system may be used by an operator to illustrate. ### Claim 54 (depends on 53) A magnetic mounting system according to claim 53 in which said first magnetic means comprises a magnet mounted to one of said magnetic symbol means and first vertical wall. ### Claim 55 (depends on 52) A magnetic mounting system according to claim 52 in which said first magnetic means comprises a magnet mounted to one of said magnetic symbol means and first vertical wall.