US 3295238 A
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Description (OCR text may contain errors)
Jan. 3, 1967 D. WINROW SIGN ELEMENT Filed Oct. 28, 1964 FIG.I
INVENTOR DONALD W/NROW.
Bwj mmaj/ United States Patent f 3,295,238 SIGN ELEMENT Donald Winrow, Downsview, Ontario, Canada, assignor to Ferranti-Packard Electric Limited, Toronto, Ontario, Canada Filed Oct. 28, 1964, Ser. No. 407,071 Claims priority, application Canada, Nov. 1, 1963,
3 Claims. 20]. 40-28) This invention relates to an improvement in the design of signs of the type described in Canadian Patent No. 641,350, dated May 15, 1962, wherein a number of magnetically controlled rotatably mounted indicia-forming elements areprovided in an array and each element is provided with two surfaces arranged to contrast with each other. The magnetic control is achieved by providing the indicia-forming element with a permanent magnet and mounting near each indicia-forming element, mag netic pole pieces in a location where end will attract or repel the poles of the permanent magnet. By controllably reversing the polarity of the pole pieces the indicia-forming element may be reversed in orientation to change the colour or appearance of the surface displayed by it, and the combination of a number of such elements in an arnay, independently controllable, is used to produce indicia which convey information.
However, it will be noted that each time such poles are reversed, the indicia element will tend to rotate in one sense or the other to its new position of rest. Thus, a series of rotations may take place, which may, in common designs of the apparatus, be all in the same sense; and if the indicia element is mounted on a filament lWl'lOS6 ends are stationary, the build-up of torsion in the filament may at some point oppose and resist a rotation of the elements under magnetic force and prevent the proper rotation thereof and therefore cause faulty portrayal of information by-the sign. v
To prevent this, the indicia-forming element and mounting are provided with stop means limiting the range of rotation of the indicia-forming element to less than 180 in each direction, with the stop means located so that the indicia element surfaces are displayed substantially to their best advantage, one in each limit position. Because of the limit on rotation, each rotation of the indiciaforming element must be the reverse of the preceding one and therefore no cumulative torsion can be built up in the supporting filament, whereby a continued sequence of operations may be assured.
Care must be taken in the location of the stop means so that the indicia-forming element cannot reach a position where the force applied by the magnetic pole pieces, and intended to reverse the position of the indicia-forming element, will tend to drive the indicia-forming element in the wrong sense against a stop. This is avoided by locating the stop means so that, with either polarity, throughout the allowed range of movement, the resultant force exerted by said pole pieces on said element magnet poles is in one direction. Preferably this is achieved by locating the stop means so that, at either end of said range, a magnet element pole is at the closest location it can assume to one pole piece and at the farthest location it can assume from the other pole piece. Again, in a preferred form this is achieved by locating the pole pieces so that the plane including them, and parallel to the axis of rotation of the indicia-forming element, has one magnet pole located on one side thereof and the other magnet pole located on the other side thereof throughout the range of movements of the magnet element.
"Preferable the members forming the pole pieces for controlling the indicia-forming elements act as the stops for Patented Jan. 3, 1967 limiting rotation of such elements and are located to intercept during rotation a portion of the indicia-forming element.
In drawings which illustrate a preferred embodiment of the invention:
FIGURE 1 shows a sign-forming element made up of 35 indicia-"forming elements in accordance with the invention, and
FIGURES 2 and 3 show an indicia-forming element and the mounting therefor with the indicia-forming element assuming opposed positions in the two views.
In relation to FIGURE 1, for a full description of the operation of such an indicia-forming sign, reference should be made to Canadian Patent No. 641,350, dated May 15, 1962.
In FIGURE 2 is shown a mounting frame 10 for the indicia-forming element 12, having a cylindrical bore therethrough, at the front end of which is the indiciaforming element 12 mounted to rotate partially in the bore by a filament 14, which extends diametrically across the bore and is attached to the element 12 and is non-rotatably attached at each end to the frame 10. A permanent magnet 15 in flat strip form, providing poles at opposed ends, is mounted so that the poles of magnet 15 preferably define an axis extending transverse to the direction of the filament 12.
Magnetic pole pieces 17 are formed by the ends of a U-shaped permanently magnetizable magnetic member, mounted by means not shown to have the free ends of the U projecting along diametrically opposed side locations in the cylindrical bore into proximity with the indicia-forming element 12, and the pole pieces preferably define a line approximately transverse to the filament 12 with the bight of the U projecting rearwardly of the frame.
An electric winding 16 on the bight of the U is provided with two terminals 18, which terminals are adapted to be provided with reversible electric current to polarize the pole pieces 17 in either sense as desired, to repel and attract the poles of the magnet 15 on the indicia-forming element to cause its rotation.
-In accordance with the invention, it will be appreciated that the indicia-forming elements 12 need not be circular, but may assume any form (for balance, preferably symmetrical about filament 14) and that the frame 10 may be of different structural form also.
In accordance with the invention, the preferred means of limiting the rotation of the indicia-forming elements 12 to slightly less than is to utilize the pole pieces 17 as stops for the elements 12.
Thus, in the preferred embodiment, the circular indiciaforrning element is made of a diameter to strike the pole pieces 17, but a portion is cut-out at 20 on one side of the element to allow passage of the pole piece to which the cut out portion is adjacent.
It will be noted that the pole pieces 17 are both located outwardly of the axis joining the poles of magnet 15. The result is that the pole of magnet 15 adjacent the cut-out 20 is, in either of the limiting positions shown in FIGURES 2 or 3, displaced inwardly with respect to the adjacent pole piece 17. Thus the energization of the pole pieces 17, to repel the adjacent poles of magnet 15, exerts magnetic force in the same direction on both indicia-element magnet poles and causes rotation of the indicia-forming element 12 in the direction which moves cut-out portion 20 inwardly, since by rotating in this sense both poles of magnet 15 are moving away from the pole pieces 17 which repel them and toward the pole pieces 17 which attract them. Thus, in either limit position of the indicia-forming element 12, the axis of the poles of magnet 15 is displaced angularly from the axis of the pole pieces 17 in the direction of rotation permitted by the pole pieces 17 acting as stops. Thus, on the energization of pole pieces 17 to repel adjacent poles of magnet 15, rotation of the indiciaforming element will always tend to and will take place away from the stops, while succeeding rotations Will always be the reverse of those just preceding, whereby continued operations do not accumulate torsion in filament 14.
It will be seen that proper operation is assured by eating the pole pieces 17 (which act as the stop means) so that, with either polarity of stop means 17 throughout the range of movement of element 12, the resultant force exerted by pole pieces 17 on the poles of magnet is in one direction. This is achieved, in the preferred embodiment, by arranging the contact of pole pieces 17 with the contacting side of element 12 so that, at either end of said range, a pole of magnet 15 is at the closest location it can assume to one pole piece and at the farthest location it can assume from the other pole piece. Again, in the preferred embodiment, this is achieved by looating the pole pieces 17 so that the plane including them and parallel to the axis of rotation of the indicia-forming element 12 has one pole of magnet 15 located on one side of such plane and the other pole of magnet 15 located on the other side of said plane within the range of movement of the magnet element.
FIGURE 2 shows the indicia-forrning element 12 in one limit position, and FIGURE 3 shows the indicia-forming element in the opposite limit position. In operation, with the indicia-forming element 12 in the position indicated in FIGURE 2, if the winding 16 is energized to create in pole pieces 17 a repulsive force to the respectively nearer poles of magnet 15, the indicia-forming element 12 is consequently rotated counter-clockwise (looking from left to right along the filament axis). The indiciaforming element 12 is, as a result, rotated to the position indicated in FIGURE 3 and stopped there as a result of the contact between the outer end of upper pole piece 17 and the ind-icia-forming element 12.
As a result of further energization of the winding 16, with a polarity opposed to that of the first energization, the polarity of the pole pieces 17 is reversed and the india- -forming element is rotated clockwise (looking from left to right along the filament axis) to the position in FIG- URE 2, where the rotation is stopped by the contact be tween the indicia-forming element 12 and the lower pole piece 17.
It will be noted that each rotation is just less than 180 and is the reverse of the previous one, so that no torsion is built up in the filament. It will :be noted that such reversal is assured by providing that in each limit position the indicia-forming element 12 is stopped so that the poles of magnet 15 and the axis between them are asymmetrical with respect to the axis and location of the pole pieces 17,
. tary frame for a large number of elements, as shown in FIGURE 1.
What I claim as my invention is:
1. In an indicating unit for a sign assembly, wherein an indicia-forming element having an axis of rotation and two surfaces of contrasting appearance is rotatably supported on a frame therefor, and a magnet adapted to respond to an applied magnetic field is mounted on said element with a pole on opposed sides of said axis; the provision of stop means arranged and constructed to limit the range of rotation of said element to less than said surfaces being so arranged on said element that one surface is displayed at one end of said range of rotation and the other surface is displayed at the other end of said range of rotation; a pair of pole pieces connectible to an electric current to assume opposed and reversible polarities, and located to provide, with either polarity, that, throughout said range of rotation, the resultant force exerted by said pole pieces on said element magnet poles is in one direction; said element and said pole pieces being so designed and located that one portion of said element contacts one pole piece on rotation in one direction and the other pole piece on rotation in the other direction whereby said stop means are thereby constituted.
2. In an indicating unit as claimed in claim 1, wherein said pole pieces are so located that, at either end of said range, an element magnet pole is at the closest location it can assume to one pole piece and at the farthest location it can assume from the other pole piece.
3. In an indicating device as claimed in claim 2, wherein said element is mounted on a filament and rotatable with an intermediate part thereof and wherein the ends of said filament are non-rotatably attached to said frame.
References Cited by the Examiner UNITED STATES PATENTS 1,191,023 7/1916 Naylor 40-28 X 3,025,512 3/1962 Bloechl 40-28 X 3,036,300 5/1962 Knight 40--28 X 3,140,553 7/1964 Taylor 40-28 EUGENE R. CAPOZIO, Primary Examiner.
W. J. CONTRERAS, Assistant Examiner.