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Publication numberUS3250031 A
Publication typeGrant
Publication dateMay 10, 1966
Filing dateFeb 12, 1963
Priority dateFeb 12, 1963
Publication numberUS 3250031 A, US 3250031A, US-A-3250031, US3250031 A, US3250031A
InventorsBowman Richard G
Original AssigneeBowman Richard G
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Display unit for scoreboards or the like
US 3250031 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

y 1966 R. G. BOWMAN 3,250,031

DISPLAY UNIT FOR SCOREBOARDS OR THE LIKE Filed Feb. 12, 1963 4 Sheets-Sheet l g f 1 5 3 .'-i "1 1- I I /l/ //'I I V 1 I I0 ll I INVENTOR. Z2 /CHQ2D 6 BOWMAN ATTORNEY ay 10, 1966 R. G BOWMAN 3,250,031

DISPLAY UNIT FOR SCOREBOARDS OR THE LIKE Filed Feb. 12, 1963 4 Sheets-Sheet 2 l/JIIII INVENTOR. ,R/CHQED G, flow/MAN EMF 12 ATTORNEY V May 10, 1966 R. G. BOWMAN DISPLAY UNIT FOR SCOREBOARDS OR THE LIKE Filed Feb. 12. 1963 4 Sheets-Sheet 4 INVENTOR.

D. 2 5 S R ATTORNEY their actuated and released conditions.

United States Patent 3,250,031 DISPLAY UNIT FOR SCOREBOARDS OR THE LIKE Richard G. Bowman, 7652 Bella Vista, Los Angeles, Calif. Filed Feb. 12, 1963, Ser. No. 257,922 3 Claims. (CI. 40-28) This invention relates to an improved display unit for use in scoreboards or other signs, and adapted to selectively form any of the different numerals 0 to 9, or if preferred to form other desired indicia such as letters or the like. Some features of the display units have been disclosed in my co-pending application Serial Number 257,890, filed February 12, 1963, on Alpha Numerical Type Display System, which covers an overall scoreboard arrangement in which a display unit embodying the present invention may be employed.

A major object of this invention is to provide an alpha numerical type multiple condition display unit which is structurally much simpler and less expensive than prior expedients intended for the same purpose, and yet which forms a display pattern having improved legibility as compared With such prior devices. A displayunit embodying the invention is capable of forming numerals or other patterns which can be read very effectively from large distances either in an indoor artificially illuminated situation, or on an outdoor field where the natural illuminationby sunlight is so great as to prevent conventional light bulb type alpha numerical units from being read satisfactorily.

In a device embodying the invention, the different numerals or other display patterns are formed by different arrangements of a plurality of individual components or display elements, each forming only a part of the overall pattern. In this connection, a particular object of the invention is to provide a system in which a minimum number of such component elements will produce all of the different numerals from 0 to 9, and will do so with the disclosed increase in legibility as compared with prior devices. For this purpose, I preferably employ an arrangement including three parallel columns of elements capable of forming all of the numerals but the numeral four, with one added element being provided for use in conjunction with the others in forming a four. To enable the formation of all of the numerals 0 through 9 with this small number of components, I find it highly desirable that the elements in the center one of the three rows be substantially wider than the elements in the other two main rows. This relative widening of the center row of component elements is presently considered to be a highly important feature of the invention, for maximizing legibility of the formed numerals, and minimizing the number of individual elements required.

Further features of the invention relate to the operational characteristics of the individual component display elements, that is, the' manner in which these elements are converted between predetermined actuated and re. leased conditions, to form the various numerals or other patterns of which the overall assembly is capable. These individual elements desirably take the form ofmovable two condition parts, preferably pivotally mounted, and adapted to be actuated; by individual solenoids between Associated with individual ones of the solenoids, I find it desirable to employ separate control relays, which for best results include reed switches having individual holding coils and triggering coils. The triggering coils of the relays are connected together in appropriate patterns to form all the various numerals which are to be written. In one form of the invention, the solenoids for actuating the display elements serve themselves as the holding coils, to thus perform a dual function and reduce the number of windings required in the apparatus.

3,250,031 Patented May 10, 1966 The above and other features and objects of the invention will be better understood from the following description of the typical embodiments illustrated in the accompanying drawings in which:

FIG. 1 is a front view, partially broken away, of a numerical display unit constructed in accordance with the invention;

IgIG. 2 is a horizontal section taken on line 2--2 of PI 1;

FIG. 3 is a vertical section taken on line 3-3 of FIG. 1;

FIG. 4 is an enlarged fragmentary horizontal section illustrating the manner in which one of the reeds and its associated coils are connected together;

FIG. 5 is a circuit diagram representing the manner in which the various trigger coils are connected together;

FIG. 6 is a front view similar to FIG. 1, but having letters applied to the different individual display elements for use in relating the trigger coils of FIG. 5 to their associated display elements;

FIG. 7 is a circuit diagram illustrating the manner in which three of the solenoids are controlled by a single reed switch;

FIG. 8 is a view representing fragmentarily a variational form of the invention; v

FIG. 9 is a view representing the manner in which all of the numerals 0 through 9 may be written by the device;

To describe first of all the structural aspects of the form 'of the invention shown in FIGS. 1 through 7, attention is at the outset drawn particularly to FIGS. 1, 2 and 3. As

seen in these figures, the display unit 10 includes a hollow rectangular housing 11 having parallel typically vertical front and rear walls 12 and 13, parallel vertical opposite side walls 14, and parallel horizontal top and bottom walls 15 and 16. All of these walls of the housing may be formed of a suitable rigid resinous plastic material, such as polystyrene. Also, a vertical partition 17 of this same plastic material may be mounted in fixed position within the housing, parallel to and approximately midway between front and back walls 12 and 13, with thin vertical partitions extending parallel to side walls 14 at the forward side of partition 17. To the back wall there may be mounted a non-conductive vertically extending resinous plastic member 18 of the channel shaped cross sectional configuration illustrated in FIG. 2. Parts 17, 18 and 125 may be secured to the engaged walls of the housing in any suitable manner, as by an appropriate cement or adhesive,

or may be molded integrally with the other walls insofar as possible.

Front wall 12 is planar and contains an opening 19 ofthe configuration illustrated in FIG. 1. At the location of this opening, there are mounted for viewing through the opening sixteen individual numeral components or display elements 20, arranged in three vertical columns C C and C with one additional element 20 being provided to the right of the column C ments 20 has two selectively exposable display faces of identical size and shape, and all of these faces of the various elements are complementary in forming together a composite display pattern which substantially completely fills the opening 19 formed in front wall 12 of the housing. As will be apparent from FIG. 1, the display faces of the individual elements 20 are desirably all of rectangular configuration, and in the case of each of the elements except those in the center column C should for best viewing be square in shape. The faces of the elements 20 in the center column C are wider horizontally than the other Each of the individual ele-' elements, and preferably wider than they are high, to have the illustrated elongated rectangular shape. For best re sults, the horizontal width of the viewing faces of elements in the center column is between about one and onefourth and one and one-half times (preferably approximately one and one-third times) the width of the other elements 20, and the height of the elements 20 in center column C As seen best in FIG. 3, the two'rectangular or square display faces of each individual element 20 are formed at 21 and 22 on two planar walls 23 and 24 which are disposed at a 60 angle A to one another, and meet along a horizontal edge 25. Walls 23 and 24 are connected together at the opposite sides of the individual element 20 by two parallel vertical side walls 26 having integrally formed ribs 27 at their inner sides. The elements 20 may be formed of resinous plastic material, such as a polystyrene, injection molded to the illustrated and discussed configuration. All of the elements 20 which are aligned in any particular horizontal row are mounted by a common horizontal shaft 28' (FIG. 1) for pivotal movement between two different positions in which the two display faces 21 and 22 respectively are positioned for viewing and aligned with and flush with the outer surface of front wall 12. For instance, the upper element 20 in FIG. 3 is positioned with its surface 21 exposed, While the next to top element 20 in that figure has its second surface 22 exposed. The five shafts 28' for mounting the five rows of elements 20 for their discussed pivotal movement extend through horizontally aligned apertures in the side walls 26 of elements 20, and in partitions 125, and are connected at their opposite ends to side walls 14 of the housing. Elements 20 may have short boss portions 20' at their opposite sides engaging partitions 1-25. The surfaces 22 of elements 20 are desirably of a neutral or background color such as white, while the surfaces 21 are of a diiferent and highly contrasting color for forming composite numerals on the background defined by such of the surfaces 22 as are in a particular instance visible. The numeral forming surfaces 21 may be of a reflectorized material, typically formed by applying an adhesive sheet of plastic tape 121 containing a multitude of glass beads to surfaces 21; or may if desired consist merely of paint having appropriate visual characteristics.

Each of the elements 20 is actuable between its two discussed display conditions by an associated solenoid 28 which may be wound upon an insulative spool 29 containing an armature 30 of magnetic material which is movable by the solenoid along a horizontal axis toward and away from the associated element 20. Each armature 30 is connected by a rigid link 31, typically formed of wire, to one of the side walls 26 of element 20, at the location of increased thickness rib 27. The connection between link 31 and each of the elements 30 and 20 is a pivotal connection, which may be made by turning the opposite ends 32 and 33 transversely through passages formed in parts 30 and 20 respectively.

The solenoids 28 associated with each of the different columns C C and C are mounted within a common vertically extending channel 34 formed of magnetic material, such as a suitable magnetically soft steel, with the spools 29 of the solenoids being cemented or otherwise secured in position within the associated channel '34, and with the various channels being secured to partition 17 by bolts 35 or otherwise (FIG. 3). Armatures 30 extend through apertures 36 in one of the two flanges of the associated channels 34, and are freely movable forwardly and rearwardly within their spools.

Each element 20 is so dimensioned that its forward edge portion 25 is heavy enough to normally return the element 20 to the position in which its face 22 is exposed, and in doing so to pull the associated link 31 and armature 30 forwardly to the position of the next to top assembly in FIG. 3. This swinging gravitationally induced movement of element 20 is limited by engagement of link 31 with rear edge 37 of wall 23. Upon energization of any of the solenoids 28, the armature in that solenoid is pulled rearwardly, to swing element 20 to a position in which its face 21 is visible, with this swinging movement being limited by engagement of the rear edge 33 of wall 24 with link 31. To properly position the parts for this extremely simple type of motion limiting action in which link 31 halts swinging movement in both directions, the pivotal axis of each rod 28' is preferably located somewhat above the horizontal axes 30" of the associated solenoids 28 and armatures 30, with the links 31 being connected to parts 20 at the locations illustrated. This renders unnecessary any extra webs, stops or other devices to limit the total rotation of the display element to a desired Thus, a simple molded plastic display part may be both operated and limited in its movement by a formed wire link attached to a soft iron armature, which may itself be a small cylinder made by cutting off a section of stock and drilling one hole for the wire link to pass through.

For controlling the pattern in which elements 20 are actuated, there are mounted to the two webs of insulative rear channel element 18 (FIG. 2) two vertical series of control assemblies 39. Each such assembly includes a plastic insulative spool 40 having an inner many turn holding coil 41, and having wound about coil 41 an outer triggering coil 42 of fewer turns. The spools 40 are cemented to the webs of element 18, and through each spool there passes a reed switch 43 (FIG. 4), suitably cemented or otherwise secured in place, and including a sealed glass envelope 44 containing two normally open reed contacts 45 and 46. Contacts 45 and 46 are magnetically actuable to closed position upon energization of trigger coil 42, by field produced by the coil, and are retainable in such closed condition by sustained energization of holding coil 41. The contacts 46 of all of the various reed switches 43 are connected to a common vertically extending terminal bar 47, desirably by soldering to that bar, with the bus 47 being connected by a lead 48 to one side of a power source 49. The other contact 45 of each reed switch is connected to one end of the holding coil 41 about that switch, with the other end of the same holding coil being connected by a lead 50 to an associated one of the solenoids 28. The second ends 51, 51a, 51b, 510, etc. all of the various solenoids, I in turn connect it to a common bus-bar or terminal 52, which is connected through an erase switch 53 to the second side of power source 49. Thus, so long as switch 53 is closed, holding current is available to all of the coils 41, and actuating crurent is available to all of the coils 28, upon closure of the corresponding reed switches 43.

For initially triggering reed switches 43 to closed condition to form appropriate patterns on the face of the display unit, the various triggering coils 42 are connected to a second power source 54 in different predetermined patterns associated with 10 different terminals 55 carried by the housing. 10 different control switches 56 are connected to terminals 55 in a manner to close'the circuit to each of the terminals when the corresponding switch 56 is closed. When the upper switch 56 of FIG. 5 is closed, the apparatus writes a 0, while closure of the second switch causes the apparatus to write a 1, etc. through the numeral 9 which is written by closure of the lowermost switch in FIG. 5.

To clarify the manner in which the various trigger coils are interconnected within the display unit, reference is first made to FIG. 6 in which the different display elements 20 of the device are designated separately as elements 20a, 20b, 20c, 20d, 20), 20c, 20 20g, 2000, 2011, Zili, 20 20ii, 20k, 20L, and 20000. The trigger coils 42 associated with these various display elements 20a, 2012, etc. are designated in FIG. 5 as coils 42a, 42b, 420, etc. As will be apparent, the energization of coil 42a closes the circuit to the solenoid for actuating element 20a; the energization of trigger coil 42b causes actuation of display element 2012, etc. Element 20r may be a numeral 0.

dummy, or a part constructed like the other elements 20 but not free for movement from its'normal position in which the neutral face of that part is exposed, since it is found unnecessary when writing numbers to ever actuate the particular element designated 20r in FIG. 6 to a display condition. With regard to the trigger coil 420, it is noted that this single coil may control the three elements designated 200, 2000, and New in FIG. 6, since these are always actuated together. For this purpose, two solenoids 28cc and 280cc (FIG. 7) for actuating the elements 20cc and 200cc may be connected in parallel with solenoid 280 (for actuating element 20c) and its holding coil 41, so that all three solenoids are under the control of a single trigger coil 42c and a single reed switch 43. Similarly, the two elements 20f and 20ii may be controlled by a single trigger coil 42i of FIG. 5.

I find it desirable to connect across each of the solenoids 28 (or 28c), and its associated holding coil 41 and reed'switch 43, a diode 120, typically of the semi-conductor type, operable to provide a short circuit path across the coils and reeds during de-energization of the coils. This shunts out the voltage induced by de-energization, and thus prevents high voltage arcing of the reed contacts to greatly lengthen their useful life.

To now describe the operation. of the apparatus of FIGS. 1 through 7, assume first of all that it is desired to write the numeral 0, as indicated in FIG. 9. To do this, the upper one of the switches 56 in FIG. 5 is closed, to passan energizing current through coils 42k, 42L, 42d, 42], 42h, 42a, 42e, 42 42c and 42b before the current is returned to source 54 through lead 154. This actuates all of the elements k, 20L, 20d, 20 20h, 20a, 20c, 20 20c, 20cc, Zllccc, and 20b, to form the desired 0. Once the appropriate reeds have been triggered to closed condiiton, they are held in that condition by passage of a holding current from the second power supply 49 through the reeds and their holding coils 41 and solenoids 28 (assuming that switch 53 is closed). The solenoids of course actuate the desired elements 20a, 20b, etc. to their active writing conditions, in the proper pattern for writing the .When it is desired to erase the numeral written, this may be done by momentarily opening switch 5-3, to release the holding circuits. To write the numeral '1, the next to top switch 56 of FIG. 5 is closed, either before or after closure of switch 53, so that a triggering circuit through coils e, j, and c is completed from power source 54, to actuate the entire vertical column C of elements 20, and thereby write the desired numeral 1. Without tracing all of the other writing circuits individually in FIG. 5, it will be apparent that closure of the other switches 56 will energize such trigger coils as to write the numerals 2 through 9 respectively. The extra width of the elements 20b, etc. in the central column C of such elements increases the legi-bility of the numerals, and enables them to he formed with a minimum number of elements. It is noted that the elements 20i and 2% are used only for the numeral 4 with the latter of these serving to form the righ-twardly projecting portion of that numeral.

The use of reed switches in the apparatus allows complete triggering of any display numeral by a single one ampere pulse of extremely short duration, say slightly over one millisecond. A resistor 121 (typically 33 ohms) may be connected into the power supply lead to the trigger coils to limit the intensity of the pulse. Once triggered the character remains displayed until. reset (erased).

From a careful analysis of FIG. 5, it will appear that, in' order to simplify the writing of the ten numerical characters, two basic trigger circuits may be employed. One of these is based on the numeral 1 (single vertical column) to which may be added other elements to form the numbers 7, 3, 4 and 0. The other basic trigger circuit includes the top, bottom and center horizontal rows to form by addition of extra display elements the characters 2, 5, 6, 8 and 9. This'type of arrangement is desirable in order to reduce the cost of manufacture of the device. As an example, the numeral 7 is formed by adding triggering coils 42a and 42b to the basic numeral 1 which is triggered by coils 42c, 42c and 42 The numeral 0 is formed by adding to the numeral 7 coils 42k, 42c, 42b, 42 and 42d, to make a complete loop ,to closed condition. The reed switch is connected in series with its corresponding solenoid 28, and is positioned close enough to the solenoid that, once the solenoid has been energized by initial triggered closing of the reed switch, the solenoid will thereafter serve itself as a holding coil acting to electrom'agnetically maintain the reed switch in closed condition. Thus, the necessity for a separate holding coil is eliminated. As in the first form of the invention, all of the holding coils and reeds may be connected in parallel to a holding current power supply (such as that represented at 49 in FIG. 3) and through a control switch. Also, the various trigger coils 42 may be connected to a second power source, through individual triggering or control switches, in a pattern corresponding to that illustrated inFIG. 5. As in the first form of the invention, the reed which is associ-ated with the solenoid which actuates element 200 of FIG. 5 may control also the solenoids associated with elements 2000 and 200cc; and the reed switch associated with the solenoid which actuates element 201' of FIG. 5 may also control the solenoid associated with element Q0ii. Except in the respects specifically discussed above, the form of the invention illustrated in FIG. 8 may be essentially identical with the =first form of the invention.

FIGS. 10 and I1 illustrate another variational arrangement, including means for facilitating return of a number of actuated display elements from their actuated positions to their released positions, upon opening of the erase switch 53 of FIG. 4. In FIG. 10, I have shown one of the vertical rows of display elements 130, which may be identical with the elements 20 of FIGS. 1, 2 and 3, and which are solenoid actuated in the same manner as are elements 20. When the solenoid-sassociated with display parts 130 are energized, these parts are actuated to the broken line positions of FIG. 10, in which they engage a series of vertically spaced circular projections or rings 131, carried by a vertical tube 132 which is mounted about a vertical guide rod 133 secured at its upper and lower ends 134 and 135 to the top and bottom walls of housing 136. Rod 133 may be attached to the housing in a manner retaining this rod against any movement relative to the housing. Tube 13 2 and its rigidly carried rings 131 are spring urged upwardly by a coil spring 137 disposed about rod 133 beneath the tube. Rings 131 are spaced vertically apart distances corresponding exactly to the vertical spacing between the different horizontal pivot rods 138 by which elements 130 are mounted for swinging movement betwen'their full line and broken line positions.

Spring 137 normally holds tube 132 and its ring 131 in the full line position of FIG. 10. The rings 131 are in this position so located as to be in the path ofswingin-g movement which walls 139 of elements 130 follow upon energization of the associated solenoids, so that if any :one of the elements 130 is actuated to its broken line position, the wall 139 of that element will engage the corresponding ring .131, and thereby displace that ring and the connected tube- 132 downwardly to the broken line position of those parts, against the tendency of spring 137. When the solenoid or solenoids are subsequently de-energized, spring 137 acts through parts 131 and 132 to impart an upward kick to each of the engaged walls 139, to thereby initiate the returning movement of all of the elements 130 in unison, and thereby prevent interference by one of the parts 130' with returning movement of another of these parts. That is, if all of the elements 130 return at the same time, from their broken line positions to their full line positions, the various corners 140 of the different elements cannot engage or interfere with one another.

As seen in FIG. 11, each of the three vertical columns of elements 130 has associated with it ,a return assembly 131-132, mounted about an associated vertical rod 133, and acting to impart initial returning movement to the elements 130 in that particular vertical row. The single right-hand element 21ii of FIG. 6 of course does not need a return unit. Spring 137 of each of the units 131-132 should be relatively weak, so that its force may be overcome by the pull exerted by a single one of the solenoids for actuating elements 130, if only one solenoid and element 130 are in a particular instance actuated. Except in the respects specifically discussed, the form of the invention shown in FIGS. 10 and 11 may be considered as identical with that of FIGS. 1 through 7.

What is claimed as new is:

1. A display assembly including a plurality of display elements adapted to form together any of various different composite symbols, said individual elements being movable in different patterns between active display positions and inactive positions, a plurality of individual solenoids for separately actuating said elements between said active and inactive positions, individual armatures of magnetic material actuate-d by said solenoids and operable to shift said elements respectively between said positions, a plurality of individual magnetically actuated reed type switches for closing electrical circuits to different solenoids respectively, a plurality of individual triggering coils for actuating different ones of said reed switches respectively between open and closed positions, and means connecting said triggering coils together in a plurality of different multiple coil triggering circuits selectively energizable to actuate said elements in said different patterns.

2. A display assembly including a plurality of display elements adapted to form together any of various different composite symbols, said individual elements being movable in different patterns between active display positions and inactive positions, a plurality of individual solenoids for separately actuating saidelements between said active and inactive positions, individual armatures of magnetic material actuated by said solenoids and operable to shift said elements respectively between said positions, a plurality of individual magnetically actuated reed type switches for closing electricalcircuits to different solenoids respectively, a plurality of individual triggering coils for actuating different ones of said reed switches respectively between open and closed positions, means connecting said triggering coils together in a plurality of different multiple coil triggering circuits selectively energizable to actuate said elements in said different patterns, and individual holding coils, in addition to said triggering coils, for retaining said switches respectively in actuated positions, and connected into a plurality of different circuits, with said different solenoids respectively and their associated reed switches.

3. A display assembly including a plurality of display elements adapted to form together any of various different composite symbols and arranged in vertical columns of said elements, individual ones of said elements having first and second walls disposed at an angle to one another and visible respectively in predetermined active and inactive positions of the elements, means mounting said elements for pivotal movement about essentially horizontal axes between said active and inactive positions, solenoids for pivotally actuating said elements to one of said positions when energized and having armatures connected to said elements, said elements and armatures being constructed to return the elements to the other of said positions by gravity upon de-energization of the solenoids, a vertically movable vertically elongated tubular structure having a plurality of shoulders disposed essentially annularly thereabout adapted to engage respectively one of said walls of each of the elements in one of said columns and actuate said elements in said one column from said one position toward said other position, a vertical rod extending through said tubular structure and mounting it for said vertical movement, a coil spring disposed about said rod and urging said structure in an upward direction to actuate said elements toward said other position.

References Cited by the Examiner UNITED STATES PATENTS 1,191,023 7/1916 Naylor 40-28 2,043,511 6/ 1936 Handley et al 40-52 2,141,473 12/1938 Hubertz 40 28 2,814,893 12/ 1957 Aiken 40 -28 3,096,594 7/ 1963 Skrobisch 40-28 FOREIGN PATENTS 625,049 6/ 1949 Great Britain.

EUGENE R. CAPOZIO, Primary Examiner.

JEROME SCI-INALL, Examiner.

WENCELSO I. CONTRERAS, Assistant Examiner.

Patent Citations
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US2043511 *Sep 4, 1935Jun 9, 1936 Indicator
US2141473 *Nov 8, 1937Dec 27, 1938Hubertz Halvard PSignaling system
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3283427 *Oct 29, 1964Nov 8, 1966Ferranti Packard LtdMethod and apparatus for construction of an electromagnetically operated sign
US3685040 *Apr 13, 1970Aug 15, 1972Science Associates IncDisplay apparatus
US4161832 *Jan 18, 1978Jul 24, 1979Nuovo Pignone S.P.A.Seven-segmented electromechanical digital indicator
US4406077 *Jun 14, 1982Sep 27, 1983Gem Signs, Inc.Changeable exhibitor
US4411084 *Jun 5, 1981Oct 25, 1983Trans-World Manufacturing Corp.Display with changeable characters
US4542603 *Mar 6, 1984Sep 24, 1985Streeter Bert EDisplay sign including changeable numeral characters
US5524371 *Jun 24, 1994Jun 11, 1996Hunter; Richard S.Display apparatus
US5778577 *Jun 14, 1996Jul 14, 1998Bailey; James DavidChangeable numeric signs
US6262698 *Feb 6, 1998Jul 17, 2001Dieter W. BlumMethod and apparatus for display sign
US20020067280 *Dec 4, 2000Jun 6, 2002Gilbert CarrilloMethod and apparatus for a portable remotely controlled tennis scoreboard
DE3021502A1 *Jun 7, 1980Dec 24, 1981Merk Gmbh Telefonbau FriedAlphanumeric display using bistable electromagnetic display elements - each comprising prism-shaped armature with two alternate display faces selected via internal polarisation magnet
EP0073842A1 *Aug 27, 1981Mar 16, 1983Friedrich Merk-Telefonbau GmbHBistable electromagnetic optical display device
Classifications
U.S. Classification40/447, 340/815.62, 40/463
International ClassificationG09G3/16, A63B71/06, G09F9/37
Cooperative ClassificationG09G3/16, G09F9/375, A63B71/06
European ClassificationA63B71/06, G09G3/16, G09F9/37M