US3228133A

US3228133A - Permanent magnet display board

Info

Publication number: US3228133A
Application number: US436499A
Authority: US
Inventors: Baermann Max
Original assignee: Max Baermann GmbH
Current assignee: Max Baermann GmbH
Priority date: 1965-03-02
Filing date: 1965-03-02
Publication date: 1966-01-11
Anticipated expiration: 1983-01-11

Description

Jan. 11, 1966 M. BAERMANN 3,228,133

PERMANENT MAGNET DISPLAY BOARD Filed March 2, 1965 2 Sheets-Sheet 1 20l S I s D S 30f 2 35N 8O N' BY f, S i, z wm, e gada,

ATTORNEYS Jan. 11, 1966 M. BAERMANN PERMANENT MAGNET DISPLAY BOARD 2 Sheets-Sheet 2 Filed March 2, 1965 NVENTOR. MAX BAERMANN ATTORNEYS United States Patent O 3,228,133 PERMANENT MAGNET DISPLAY BOARD Max Baermann, Bensberg Wulfshof, Bezirk Cologne, Rhine, Germany Filed Mar. 2, 1965, Ser. No. 436,499 22 Claims. (Cl. 40-142) This invention pertains to the art of display boards and more particularly to a parmanent magnet display board.

The present invent-ion is particularly applicable to a visual display board of the type used in hotels, railway stations, airports and the like for visually exhibting various information and messages and it will be described with particuluar reference thereto; however, it is to be appreciated that the invention has much broader applications and may be used in other visual display devices.

It has become somewhat common practice to mount individual letters on a display board in hotels, railway stations, airports and the like for announcing various information and messages, such as departure time, room numbers for selected activities, prices, etc. In the past, these visual display boards usually included a board with horizontally extending grooves or recesses arranged across the face of the board. The board was covered with a felt or other fabric which did not interfere with the horizontal grooves. Letters or other symbols to be used in conjunction with the board were constructed with a rearwardly extending lug or plug having a thickness corresponding substantially to the width of the horizontally extending grooves -in the display board. The letters were secured onto the board by pressing the rearwardly extending plug or lug on each letter into the grooves where the letters were held by friction. This type of display board was quite expensive because of the cost involved in making the horizontally extending grooves and the individual letters with rearwardly extending attaching means. In addition, these display boards were somewhat unsightly because the horizontally extending grooves were generally visible to a person reading the message on the board.

To overcome the obvious disadvantages surrounding the use of the horizontally grooved visual display board, it has been proposed to use a magnetic display board. In the past these magnetic display boards utilized one of two constructions. First, a high permeability material, such as soft iron, was used as a display board and the letters were made of permanently magnetic material. The permanent magnet material was attracted to the high permeability material to hold the letters in place on the surface of the display board. The second general construction involved a generally at sheet of permanently magnetic material provided with a plurality of north and south lpermanent magnetic poles and the letters were formed from high permeability, ferro-magnetic material. With this construction, the letters were attracted to the permanent magnetic sheet. Both of these permanent magnet display boards had a common disadvantage. There was no Way of aligning the letters in a straight line along the display board. For this reason, it was generally necessary to provide a special implement, such as a guiding ruler, for aligning all letters across the surface of the permanent magnetic display board. In addition, the letters quite often became dislodged. Thus, they required periodic alignment to maintain the straightness of the letters extending across the surface of the display board.

These and other disadvantages of prior magnetic display boards have been overcome by the present invention which is directed toward a visual display board of the magnetic type wherein the letters or symbols can be easily aligned horizontally on the board without accessory aligning implements.

ICC

In accordance with the present invention, there is provided a visual display board comprising a permanent magnet layer having a large area, substantially iiat mounting surface facing outwardly from the layer, a plurality of parallel equally spaced, alternate north and south magnetic poles extending along the mounting surface, a plurality of equiheight symbols to be mounted in a straight line on the mounting surface, the symbols each having a Ipermanent magnet attaching surface, a plurality of parallel equally spaced, alternate north and south magnetic poles extending along the attaching surface, the magnetic poles on the attaching surface extending substantially horizontal of the symbols and spaced the same as the magnetic poles on the mounting surface, and the lowermost pole on each symbol being of like polarity and positioned at the same location as the lower-most poles on the other like symbols.

By constructing the visual display board in accordance with the invention defined above, the parallel magnetic poles, extending along the attaching surface of the symbols, are attracted by the parallel magnetic poles on the mounting surface of the magnetic layer so that the symbols are automatically and exactly positioned on a straight line and at the same height across the face of the mounting surface. When properly positioned, the magnetic poles on the symbol face and are attracted to opposite polarity magnetic poles on the mounting surface. I-f a letter is positioned on the mounting surface in the incorrect vertical Iposition, the letter will automatically jump into the proper aligned position on the mounting surface with the magnetic poles on the symbols matching corresponding, lbut opposite polarity, magnetic poles on the mounting surface. Also, if the symbols are canted with respect to the intended straight line mounting position, the magnetic poles on the mounting surface and the magnetic poles on the symbol will coact to rotate the symbol into its proper position. This provides a simple and inexpensive arrangement whereby the letters or symbols can be easily placed in a straight line without requiring an auxiliary implement for aligning the symbols on the display board.

In accordance with another aspect of the present invention, the magnetic layer on the board and the magnetic surface of the symbol are formed from a mixture of high coercivity permanent magnet particles and a plastic binder with the particles dispersed throughout and bonded by the binder. In accordance with the preferred embodiment of the invention, the magnetic particles are formed from barium ferrite and the binder for both the mounting surface and the symbols is a thermoplastic flexible material which will allow flexing of these various elements. The magnetic layer forming the mounting surface may be secured onto a support plate to prevent ilexing of the layer when it is required that the board be somewhat rigid.

In accordance with the invention, the magnetic layer may be laminated, cast or injection molded. The same is true of the symbols when these symbols are formed from permanent magnet material. In the case of the symbols, the material may be cut `or punched into the proper shape before or after magnetization.

In accordance with another aspect of the present invention, the mounting surface of the board is provided with a decorative coating to impart the desired color or design thereto. This ican be accomplished by applying a coating of paint, lacquer or other such material by brushing, dipping, or spraying. In addition, a thin colored sheet may be adhesively secured 4onto the mounting surface to impart a decorative appearance to this surface.

In accordance with another aspect of the present invention, there is provided a visual display device comprising an endless belt `of flexible permanent magnetic material having a mounting surface facing outwandly from the belt, a plurality of parallel equally spaced, alternate north and south magnetic poles extending longitudinally along the belt and on the mounting surface, a plurality of equiheight symbols to be mounted in a straigiht line on tthe mounting surface and longitudinally of the belt, the symbols each being formed of a flexible permanent magnet material and having an attracting surface, a plurality of parallel equally spaced, alternate north and south magnetic poles extending along the attaching surface, the magnetic poles on the attaching surface extending substantially horizontal of the symbols and spaced the same as the lmagnetic poles on the mounting surface, the lowermost pole on each symbol being of like polarity and positioned at the same location as the lowermost poles on the other like symbols, a driven drum and onother drum, the belt being entrained around the drums and movable in a longitudinal direction by the driven drum.

In accordance with still a further aspect of the present invention, there is provided a visual -display board comprising a layer having a large area, substantially tlat mounting surface facing outwardly from the layer, a plurality 4of parallel equally spaced, ferro-magnetic pole pieces extending along the mounting surface, the layer including non-magnetic portions between the pole pieces, a plurality of equi-height symbols t-o be lmounted in a straight line on the mounting surface, the symbols each liaving a permanent magnet attaching surface, a plurality of parallel equally spaced, magnetic poles extending along the attaching surface, the magnetic poles on the attaching surface extending substantially horizontal of the symbols and spaced the same as the pole pieces lon the mounting surface.

The primary object of the present invention is the pnovision of a magnetic, visual display board having symbols magnetically attracted thereto which board is easy to produce and durable in use.

Another object of the present invention is the provision of a magnetic, visual display board having symbols magnetically attracted thereto which board allows easy alignment of the symbols in a straight line.

Another object of the present invention is the provision of a magnetic, visual display board having symbols magnetically attracted thereto which board allows alignment of the symbols is a straight line without auxiliary implements.

Yet another object of the present invention is the provision of a magnetic, visual disp-lay board having symbols magnetically attracted thereto which board includes a magnetic layer with a plurality of parallel poles and symbols with a plurality of similar parallel magnetic poles with the poles being used to align the symbols in a straight line on the magnetic layer.

Still a further object lof the present invention is the provision of a magnetic, visual display board having s-ymbols magnetically attracted thereto which board is in the form of an endless belt of permanent magnet material and symbols of flexible permanent magnet material adapted to be magnetically attracted to the endless belt.

These and other objects and advantages will become apparent from the following description used to illustrate the preferred embodiment of the invention as read in connection with the accompanying drawing in which:

FIGURE l is a plan view illustrating the preferred embodiment of the present invention;

FIGURE 2 is a partial plan view illustrating a portion of the preferred embodiment as shown in FIGURE l;

FIGURE 3 is a partial cross-sectional view taken generally along line 3 3 of FIGURE l;

FIGURE 3A is a cross-sectional view similar to FIG- URE 3 showing a Imodification of the preferred embodiment of the present invention;

FIGURE 4 is a partial plan view illustrating a further modification of the present invention;

FIGURE 5 is a pictorial view illustrating a further aspect of the present invention;

FIGURE 6 is a pictorial view illustrating a modication of the aspect shown in FIGURE 5;

FIGURE 7 is 'a graphic view illustrating, somewhat schematically, the operating characteristics of the present invention.

FIGURE 8 is a pictorial View showing still a further modification of the present invention; and,

FIGURES 9, 10 and 11 are partial, pictorial views illustrating modifi-cations of the preferred embodiment of the invention as shown in FIGURES 1 8.

Referring now to the drawing wherein the showings are for the purpose of illustrating preferred embodiments of the invention only and not for the purpose of limiting same, FIGURES 1 3 show a visual display board A of the type used to exhibit symbols, such as letters, for constructing an appropriate message. In accordance with the invention, the board A is formed from a layer 1t) of permanent magnetic material. In accordance with the preferred embodiment of the present invention, the permanent magnet material is formed from particles of high coercivity, low permeability permanent magnetic material and a thermoplastic binder with the particles dispersed throughout and bonded by the binder. In accordance with a more limited aspect of the present invention, the permanent magnet particles within the binder are formed from barium ferrite and the binder itself is flexible whereby the layer Ill can be formed by casting, extruding or milling in accordance with known procedures.

The premanent magnet layer lll' is provided with an outwardly facing mounting surface 12 and a rearwardly facing surface I4. By an appropriate magnetizing device, such as a plurality of single wires extending parallel along the mounting surface and/tor the rear surface of the layer lll, a plurality of parallel opposite polarity, equally spaced

magnetic poles

20, 22 are provided on the mounting surface 12 and rear surface I4. In accordance with the illustrated embodiment of the invention, Ztl is a south magnetic pole and 22 is a north magnetic pole each of lwhich poles extend longitudinally across the face of the display board A. The provision of these parallel, opposite polarity magnetic poles forms an important part of the present invention as will be hereinafer explained in detail.

To rigidify the flexible layer lll, there is provided a support plate Ztl secured onto rear surface lli. In accordance with the embodiment of the invention shown in FIGURES 1 3, this support plate is in the form of a high permeability material so that magnetic poles at the rear surface 14 can direct llux lines through the high permeability plate for increasing llux density of the poles 2li, 22 extending across the mounting surface l2. As will be explained later, it is possible to provide the layer It) with magnetic poles only on the mounting surface 12 without departing from the intended spirit and scope of the present invention.

A plurality of equiheight symbols 40, in the form of letters, are to be mounted in a straight horizontal line across the mounting surface 12 to exhibit an appropriate message. In the past, such symbols were formed from high permeability material. There was no accurate way of aligning these symbols in a horizontal direction on the mounting surface. In accordance with the present invention, the symbols themselves are formed from a permanent magnet material, which, in accordance with the preferred embodiment of the present invention, is a material similar to that used in forming the permanent magnet layer 10. The symbols are provided with an attaching surface 42 having parallel, opposite polarity

permanent magnet poles

50, 52 which are equally spaced the same distance as

poles

20, 22 of the layer 10. In accordance with this embodiment of the invention, there are provided an odd number of magnetic poles because the height of the symbols substantially corresponds to the vertical distance occupied by an odd number of magnetic poles on the mounting surface 12. The

magnetic poles

50, 52 are provided on the attaching surface 42 of each symbol 40 so that the bottom-most magnetic pole of each symbol has a like polarity and is positioned substantially at the sarne location as the lowermost magnetic lpole of all equiheight symbols 40.

It is readily apparent that by constructing the symbols 40 in accordance with the present invention, the symbols may be secured onto the mounting surface 12 with the

magnetic poles

50, 52 of each symbol being attracted by an opposite polarity

magnetic pole

20, 22 of the mounting surface 12 of board A. This arrangement of the magnetic poles causes the symbols to align themselves with respect to the mounting surface with the poles 50 being directly opposite poles and the poles 52 being directly opposite poles 22.

Referring now to FIGURE 7, the arrows x represent the vector direction of the magnetic fields from the north magnetic poles 22, S0 of the layer 10 and symbol 40, respectively. The arrows y represent the vector direction of the magnetic fields from south

magnetic poles

20, 52 of the layer 10 and symbol 40, respectively. The distance a represents the vertical spacing between the corresponding arrows x and y. In the equilibrium condition, the vector or arrows x and y must correspond and lie one over the other; therefore, the distance a must be reduced to Zero before the symbols 40 come to rest on the mounting surface 12. Consequently, since the spacing of the poles is the same on all symbols 40, when the symbols come to rest with the distances a being zero, all symbols 40 are positioned in a straight line with respect to the mounting surface 12. Although the FIG- URE 7 represents a vertical displacement between poles on the symbols l0 and thecorresponding poles on the surface 12, the same general principle applies when the symbols l0 are canted or rotated with respect to this proper position on the mounting surface 12. When this happens, the symbols 40 will not come to rest until the symbols are rotated by the magnetic force schematically represented by the distance a. The rotation will stop when the distance a is substantially zero. It is easily appreciated that this arrangement provides an efiicient arrangement for aligning the symbols 40 in a straight line across the mounting surface without accessory implements being required. This is a substantial advance over any known magnetic visual display board.

Referring now to FIGURE 3A, a slight modication of the present invention is illustrated. The layer 10 is not provided with a support plate so that the layer can be easily exed if the binder is flexible or can be substantially rigid if the binder is rigid.

Poles

20, 22 are provided on mounting surface 12 in a manner previously explained. Since a permanent magnet layer 10 may not have an inherently attractive color or design, in accordance with the invention, a coating 60 is provided on the mounting surface 12. This coating 60 may be a paint or lacquer sprayed, brushed or dipped onto the mounting surface. In addition, this coating 60 may be a vulcanized layer or it may be a sheet of non-magnetic material glued or adhered onto the mounting surface 12. irrespective of the particular manner or method for securing the coating 60 onto the mounting surface, this coating does form a decorative layer for the surface 12 so that the surface has a pleasing appearance. The embodiment of the invention shown in FIGURE 3A does not have magnetic poles at the rear surface 14; however, this does not affect the basic operating characteristics of this embodiment which are substantially identical to the embodiment shown in FIGURES 1-3.

Referring now to FIGURE 4, the symbol 70 is constructed substantially in accordance with the same procedure utilized in constructing the symbols 40; however, the symbol is larger to the extent that an additional set of opposite polarity

permanent magnet poles

50, 52 are provided thereon. The lowermost pole is aligned with the lowermost pole on similar symbols 70 so that they can be positioned onto the mounting surface 12 in accordance with the procedure previously described in detail. It is also appreciated that the symbol 70 may be utilized in combination with symbols 40 wherein the lower edge of each symbol can be accurately positioned in a straight line across the mounting surface 12 by the procedure previously described. It is also appreciated that the

symbols

40, 70 may be provided with an even number of opposite polarity magnetic poles spaced the same as the

magnetic poles

20, 22 with the lowermost pole on each symbol having the same polarity and being positioned in substantially the same location as the lowermost pole on other symbols to be used therewith.

In FIGURE 5 there is illustrated a vertically shortened symbol which is to be positioned in line with, but somewhat midway between the top and bottom edge of

symbols

40 and 70. To accomplish this function, the symbol 80 is provided with a lower attaching surface 82 with a longitudinally extending permanent magnet pole 84, shown as a south pole. A north magnetic pole is positioned at the upper surface of the symbol 80. To secure the symbol 80 onto the mounting surface 12, the pole 84 is attracted onto the pole 22 of the vertical midpoint of symbol 40. If the symbol 80 were to be used with a symbol 70, the polarization of poles 84, 86 would have to be reversed since the center pole of symbol 70 is opposite in polarity to the central pole of symbol 40. This modification would be obvious to a person with ordinary skill in the art of permanent magnets after reading this application.

Referring now to FIGURE 6, another vertically shortened symbol 90 is disclosed having attaching surface 92 with longitudinally extending, opposite polarity

magnetic poles

94, 96. The spacing between these poles corretsponds to the sepaoing between

poles

20, 22 of the mounting surface 12. This particular shortened symbol can be utilized when an even number of poles are provided on 'the attaching surfaces of

symbols

40, 70. In addition, this particular type of shortened symbol could be utilized wit-h symbols 40, '70 if the symbol 90 were to be displaced vertically with respect to the 4midpoint between the top and bottom edges of these symbols.

The

symbols

40, 70, 80 and 90 can be constructed by first magnetizing a large sheet and then accurately cutting or punching the symbols from this sheet so that the lowermost pole -of each symbol has a like polarity and is positioned in the same position as .the other lowermost magnetic poles of symbols to be used therewith. Also, the symbols may be first cut or punched and -then m-agnetized with the same requirement on polarity and position of the lowermost magneti-c pole. It has been found that the symbols contemplated by the present invention may have a laminated construction with an outer ferromagnetic plate land/or an outer decorative coating. These modifications are lall within the contemplated scope of the present invention.

Another modification of the present invention is illustrated in FIGURE 8 wherein a visual display device 100 includes the layer 10 in the form of an endless belt 102. The belt is formed of a exible material as are the symbols 40, especially when the symbols have a large area. Bel-t 102 is entrained abound drum `110 which is in turn driven by schamatically represented mot-or 112 by a shaft 114. Spaced from drum is a second drum 116 around which the endless belt 102 is also entrained. In operation, the belt 102 is driven around the

drums

110, 116 so that the message formed by symbols 40 continuously -moves in a horizontal direction.

The embodiments of the invention disclosed lin FIG- URES l-S relied upon the magnetic `aligning characteristics of two sets of longitudinally extending, magnetic 7 poles for assuring proper alignment of the symbols on the display board. In FIGURES 9-11 a similar magnetic aligning charactertistic is used in three modifications of the preferred embodiment of the present invention.

Referring now to FIGURE 9, a layer or board 110 is formed from a non-magnetic material, such as wood or a non-magnetic metal, and a plurality of longitudinally extending grooves 112 are machined, molded or otherwise formed in the outwardly facing, mounting surface 114. In accordance with this embodiment of the invention .the parallel grooves 112 are filled witth a ferromagnetic rnateria-l, such as strip 116 of soft iron. These strips 116 form parallel, equally spaced pole pieces that align a symbol 120 with respect to surface 114 by the action of

magnetic poles

124, 126 on the attaching surface 128 -of the symbol. The interaction of the pole pieces and magnetic poles cause unbalancing aligning forces between -the symbol 120 and the layer 110 until the symbol assumes a position wherein the magnet poles and the pole pieces are parallel with respect to each other, in which position the symbol is horizontal. Vertical alignment of a plurality yof poles is assured because the magnetitc pole on each symbol will assume a predetermined vertcial position with respect to parallel pole pieces.

In FIGURE l0, the layer or board 110 is basically identical with the layer or board in FIGURE 9; however, the parallel grooves are filled with a ferro-magnetic material 130 comprising a mixture of ferro-magnetic particles and a non-magnetic binder. In accordance with the preferred embodiment -of the modification shown in FIGURE l0, the ferro-magnetic particles are formed from from soft iron and the binder is a plas-tic material.

Referring now to FIGURE l1, another embodiment is illustrated wherein the board 140 is formed from a sheet of ferro-magnetic material folded transversely t=o provide a plural-ity of parallel, longitudinally extending grooves 142 which grooves a-re equally spaced a distance corresponding to the spacing between -the

parallel poles

124, 126 on attaching surface 128 of symbol 120, as shown in FIGURE 9. To provide a fiat mounting surface 1433, the grooves 142 are filled with a plastic, nonmagnetic material 144. It is appreciated that various non-magnetic materials could Ibe provided within the groove or, under certain circumstances, the grooves could be left unfilled. The alignment of symbols onto the mounting surface 143 is substantially identical to the alignment accomplished with respect to the embodiments shown in FIGURES 9 and l0. The magnetic characteristics of the components shown in FIGURE 11 could be reversed and board 140 could be formed from a nonmagnetic metal, such as aluminum, and the material 144 could be a ferro-magnetic material, such as strips 116 or mixture 130.

The present invention has been described in conjunction with certain structural embodiments; however, it is to lbe appreciated that various structural changes may be made in the illustrated embodiments without departing from the intended scope and spirit of the present invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A visual display board comprising a perment magnet layer having a large area, substantially fiat mounting surface facing outwardly from said layer, a plurality of parallel equally spaced, alternate north and south magnetic poles extending along said mounting surface, a plurality of symbols to be mounted in a straight line on said mounting surface, said `symbols each having a permanent magnetic -attaching surface, a plurality of parrallel equally spaced, alternate north and south magnetic poles extending along said attaching surface, said magnetic poles on said .attaching surface extending in `a preselected direction with respect to said symbols and spaced the same as said magnetic poles on said mounting surface, and one outermost pole on each symbol being of like d polarity and positioned at the same location as the corretsponding outermost poles on the other like symbols.

2. A visual display board as defined in claim 1 including a vertically shortened symbol `to be mounted on said mounting surface midway ybe-tween said first-mentioned symbols, an odd number of parallel magnetic poles on said first-mentioned, symbols, said `shortened symbol having a permanent magnetic attaching surface with a single elongated magnetic pole, said single elongated magnetic pole having the same pola-ri-ty as the center magnetic pole of said first mentioned symbols.

3. A visual display board as defined in claim 1 including a vertically shortened symbol to be mounted on said mounting surface midway 4between said first-mentioned symbols, an even number lof parallel magnetic poles on said first-mentioned symbols, said shortened `symbol having `a permanent magnetic attaching surface with a pair fof elongated, opposite polarity magnetic poles, said pair of poles having the same polarity as the center pai-r of magnetic poles of said first-mentioned symbols.

4. A visual display board as defined in claim 1 wherein said permanent magnet layer is formed from a mixture of high coercivity permanent magnetic particles and a plastic Ibinder with .the particles dispersed throughout and bonded `by said binder.

S. A visual display lboard as defined in claim 4 wherein said permanent magnetic particles are barium ferrite.

6. A visual display board as defined in claim 1 wherein said permanent magnetic attaching surface is formed from a layer including a mixture of high coercivity permanent magnetic particles and a plastic binder with the particles dispersed throughout and bonded by said binder.

7. A visual display board as defined in claim 6 wherein said magnetic particles are barium ferrite.

8. A visual display board as defined in claim 1 including a ferro-magnetic plate, said magnet layer having an attaching surface on the side opposite said mounting surface and means for securing said attaching surface of said layer onto said ferro-magnetic plate whereby said plate forms a fiux director at said attaching surface of said layer.

9. A visual display board as defined in claim 1 including a somewhat rigid support plate, said layer being secured onto said support plate with said mounting surface facing outwardly from said plate.

10. A visual display board as defined in claim 1 including a thin, decorative, non-magnetic layer coextensive with said mounting surface and secured thereto.

11. A visual display board as defined in claim 1t) wherein said decorative layer comprises a colored paint.

12. A visual display board as defined in claim 11 wherein said paint is vulcanizable onto said mounting surface.

13. A visual display board as defined in claim 10 wherein said decorative layer comprises a thin non-magnetic foil adhesively secured onto said mounting surface.

14. A visual display device comprising an endless belt of flexible permanently magnetic material having a mounting surface facing outwardly from said belt, a plurality of parallel equally spaced, alternate north and south magnetic poles extending longitudinally along said belt and on said mounting surface7 a plurality of equi-height symbols to be mounted in a straight line on said mounting surface and longitudinally of said belt, said symbols each formed of a fiexible permanently magnetic material and having an attaching surface, a plurality of parallel equally spaced, alternate north and south magnetic poles extending along said attaching surface, said magnetic poles of said attaching surface extending substantially horizontal of said symbols and spaced the same as said magnetic poles on said mounting surface, the lowermost pole on each symbol being of like polarity and positioned at the same location as the lowermost poles of the other symbols, a driven drum and another drum, said belt being entrained around said drums, and movable in a longitudinal direction by said driven drum.

15. A visual display device as defined in claim 14 wherein said fiexible magnetic material is formed from a mixture of high coercivity permanent magnetic particles and a fiexible plastic binder with the particles dispersed throughout and bonded by said flexible binder.

16. A visual display board comprising a layer having a large area, substantially flat mounting surface facing outwardly from said layer, a plurality of parallel equally spaced, ferro-magnetic pole pieces extending along said mounting surface, said layer including non-magnetic portions between said pole pieces, a plurality of equiheight symbols to be mounted in a straight line on said mounting surface, said symbols each having a permanent magnetic attaching surface, a plurality of parallel equally spaced, magneticpoles extending along said attaching surface, said magnetic poles on said attaching Surface extending substantially horizontal of said symbols and spaced the same a-s said pole pieces on said mounting surface.

17. A visual display board as defined in claim 16 wherein said layer pole pieces are formed from ferromagnetic particles dispersed throughout and bonded Within a non-magnetic binder.

1S. A visual display board as defined in claim 17 wherein said ferro-magnetic particles are formed from iron.

19. A visual display board as defined in claim 16 wherein said layer is formed from a non-magnetic material with longitudinally extending grooves on said mount- 30 ing surface, and said pole pieces are formed from ferromagnetic material secured within said grooves.

20. A visual display board as defined in claim 19 wherein said non-magnet material is formed from a sheet of non-magnetic metal, said sheet being folded in a transverse direction to form said longitudinally extending grooves.

21. A visual display board as defined in claim 16 wherein said layer is formed from a ferro-magnetic material with longitudinally extending grooves, said nonmagnetic portions between said pole pieces being formed from non-magnetic material secured within said grooves.

Z2. A visual display board as defined in claim 21 wherein said ferro-magnetic material is formed from a sheet of ferro-magnetic metal, said sheet being folded in a transverse direction to form said longitudinally extending grooves.

References Cited by the Examiner UNITED STATES PATENTS 1,168,949 1/1916 McKittriclt et al 40--142 1,395,982 11/1921 Gee 40-142 1,624,741 4/1927 Leppke et al 40--142 1,677,919 7/1928 Hansen 40-142 2,254,498 9/1941 Scharf 40--142 2,600,505 6/1952 Jones 40-142 2,959,832 11/1960 Baermann 24--201 3,008,209 11/1961 Kurt 24-203 3,095,668 7/1963 Dorsett 46--25 EUGENE R. CAPOZIO, Primary Examiner'.

SHELDON M. BENDER, Examiner.

Claims

16. A VISUAL DISPLAY BOARD COMPRISING A LAYER HAVING A LARGE AREA, SUBSTANTIALLY FLAT MOUNTING SURFACE FACING OUTWARDLY FROM SAID LAYER, A PLURALITY OF PARALLEL EQUALLY SPACED, FERRO-MAGNETIC POLE PIECES EXTENDING ALONG SAID MOUNTING SURFACE, SAID LAYER INCLUDING NON-MAGNETIC PORTIONS BETWEEN SAID POLE PIECES, A PLURALITY OF EQUIHEIGHT SYMBOLS TO BE MOUNTED IN A STRAIGHT LINE ON SAID MOUNTING SURFACE, SAID SYMBOLS EACH HAVING A PERMANENT MAGNETIC ATTACHING SURFACE, A PLURALITY OF PARALLEL EQUALLY SPACED, MAGNETIC POLES EXTENDING ALONG SAID ATTACHING SURFACE, SAID MAGNETIC POLES ON SAID ATTACHING SURFACE EXTENDING SUBSTANTIALLY HORIZONTAL OF SAID SYMBOLS AND SPACED THE SAME AS SAID POLE PIECES ON SAID MOUNTING SURFACE.