FR2460532A1 - PERMANENT MAGNET FOR BISTABLE ELEMENT AND BISTABLE ELEMENT AND DATA VISUALIZATION UNITS WITH AT LEAST ONE MEMBER - Google Patents

Abstract

1. Permanent magnet (6) for a bistable element (1, 8) which may be actuated by magnetic means (10) and is a component of a data display unit (2, 30, 31), the said element comprising : - a rotor (1) formed by a body (2) on the exterior of which two opposite faces (2a , 2b ) are defined and bear markings (3a , 3b ) which are different from one another ; - the permanent magnet (6) made rotationally rigid with the body (2) of this rotor (1) and to which it is fixed in a position such that the line (7) passing through its NORTH and SOUTH poles is radial with respect to the rotation shaft (4) of the rotor (1), the magnet having a form such that its polar zones (23, 24) are symmetrical with respect to the said shaft (4) ; - a stator (8) comprising a support (9) ; - an electromagnet (10) fixed to this support (9) in a position such that its NORTH and SOUTH poles are substantially disposed both symmetrically with respect to the rotation shaft (4) of the rotor (1) and in the plane of rotation of the poles of the permanent magnet (6) with respect to the shaft (4) of the rotor (1) ; - a means for connecting the electromagnet (10) to a direct current source enabling a transient supply with reversible polarity, this magnet being characterized in that, in the plane of rotation of the permanent magnet (6), each of its polar zones (23, 24) has a contour (21, 22) which defines a first zone part (23a , 24a ) located on one side of the line (7) passing through the poles of the magnet (6) and a second part (23b , 24b ) located on the other side of this line (7), the contour of the first part (23a , 24a ) being further from the shaft (4) of the rotor (1) than the contour of the second part (23b , 24b ).

Description

The invention relates to a permanent magnet for a bistable element

  actuated by magnetic means and to those data display elements and units provided with

least such an element.

  In such a bistable element, the visualization of the data is obtained by means of a rotor formed of a cylindrical body (US Pat. No. 2,740,955), spherical (US Pat. No. 3,036,300) or even plate (US Pat. No. 1,191,023) of which one of the two surfaces that are, for each above-mentioned body shape, respectively, the halves of the lateral face, the hemispherical surfaces or the opposite faces, is carrying, at least locally, a

  indication different from that given by the other surface.

  For example, these different indications will be conventional color ranges such as white or yellow on the one hand

and black on the other hand.

  According to the surface thus offered to the view, this body thus displays an indication that is self-sufficient (US Patent 2,415,452 and 2,740,955), is / participates, in combination with other elements, the construction a more complex indication, such as for example & the restitution of characters (US Patent 1,191,023, 1,799,731 and 3,036,300). Cos characters allow

  then, among other applications, to compose

  recording of schedules, for stations, terminals, sports results, etc ... As announced above, to correctly orient each bistable telescopic rotor, it is actuable in rotation of one hundred and eighty degrees around its axis, by magnetic means. Such magnetic means are described in the aforementioned patents and in many other documents and for example in US Pat. No. 3,025,512 in which, in addition to the rotor, these magnetic means comprise: a permanent magnet secured to the rotor to which it is attached; in a position such that the axis passing through

  the NORTH and SOUTH faces of the permanent magnet are sensitive-

  radial arrangement with the rotation tax of the rotor, - a stator formed of a support for the component below, - an electromagnet fixed to the stator and in a position such that its north and south legs are arranged substantially

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  both symmetrically to the axis of rotation of the rotor and in the plane in which, together with this rotor, rotate the pins of the rotor permanent magnet, - a fugitive connection means of the electromagnet & a source of direct current of reversible polarity. It is known that: on the one hand, two magnets brought into contact with each other exert attraction forces at their ends of different polarity and repulsion at their ends of the same polarity and on the other hand, the inversion of the polarity of the direct current supplying the electromagnet leads to a reversal of the direction

  of the magnetic field of this electromagnet.

  It is therefore understood that, depending on the direction of the magnetic field created by the electromagnet of the stator, the permanent magnet and therefore the rotor are held in their place if the permanent magnet is well oriented or rotated on a angle of one hundred and four

  Twenty degrees so that the permanent magnet has its correct posi-

tion.

  The power supply of the electromagnet can immediately be inter-

  broken because mime if they did not offer remanent magnetization, being magnetic material, just bars

  bearing the North-South poles of the electromagnet would attract

  core of the permanent magnet and the rotor would remain so

  stabilized in the position imposed by the last commando.

  The operation of such a bistable element is therefore simple

in principle.

  However, a problem would arise if, before a rotation control, the rotor had stabilized in a position where the axis

  passing through the north-south poles of its permanent magnet confron-

  was perfectly in line with the North and South Pole

of the electromagnet.

  Indeed, the repulsive forces would not generate any

  torque, but would balance.

  In order to overcome this disadvantage, in combination with the magnetic actuation means, it is known to use other means which, for their part, intervene so that between the

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  commands, the axes of the North and South poles of the electromagnet and that of the permanent magnet are always shifted one by

report to the other.

  Among these other means, there are mainly mechanical stops generally limiting the angle of rotation of the rotor relative to the stator to less than one hundred and eighty degrees (US Patent 3,025,512) which obviously, on the one hand, when

  cylindrical or spherical body, reduces the surface area

  sand for the display and especially, on the other hand, in flat-shaped bodies, inclines the display surfaces and that of a different angle depending on the surface that is exposed to the view, which,

  in at least one of the positions, may hinder visibility.

  In alternative embodiments, some of which make it possible to maintain a complete pivoting of one hundred and eighty degrees, to the action of these mechanical stops, combines the action of a magnetic field created by an additional permanent magnet and which is carried by the stator (US Pat. No. 2,740,955 and 3,518,664) and / or the action resulting from a characteristic positioning of the permanent magnet of the rotors, which permanent magnet, when the rotor is stabilized, can indeed have the axis of its North and South poles which, with respect to that of the poles of the electromagnet is shifted in parallel (US Pat. No. 2,740,955) or is inclined (US Pat. No. 3,624,941). With all these other means, the removal of the poles of the electromagnet from those of the permanent magnet decreases the attraction at rest and therefore impedes the stability of the rotor between the controls. Moreover, because of these mechanical and / or magnetic means other than those indispensable for actuating the rotor, such a bistable element is both complex and above all

  bulky and high cost.

  These are all the more serious defects since said element is rarely used alone but, generally, is used in

very large quantity.

  For example, if only to constitute a single variable character, units of thirty-five of these elements, divided into five vertical rows of seven, are already commonly used.

elements each.

  Therefore, a result that the invention aims to obtain is a permanent magnet for a bistable element of the aforementioned type which, so that its rotor does not stabilize in positions where the axes of the permanent magnet of the rotor would merge with each other. of

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  of a display unit - Figure 7: schematically, such a unit view profile

  - Figure 8: schematically, the front of such a unit.

  Referring to Figures 1 and 2, we see that this bis-

  table comprises a rotor 1 formed of a cylindrical body 2, whose side surface carries, in known manner, in two diametrically opposite zones 2 a, 2 b 'different indications

  3 a '3 b' such as a pellet 3a of yellow color reflecting

  torisante and a pellet 3 b 'black and matte color.

  The rotor 1 is carried by an axis 4 which is free to rotate

  in a bearing 5 ensuring its rotational guidance and its immobili-

  translation in at least one direction and

this will be explained later.

  To orient the rotor correctly, in order to make it

  the indications 3a, 3b, which is

  it is operated in rotation by magnetic means.

  comprising: - a permanent magnet 6 secured in rotation with the rotor 1 to which it is fixed in such a way that the axis 7, passing through

  its North N 6 and South S 6 * flights are radial to the turnover tax.

  the rotor - a stator 8 formed of a support 9 for an electromagnet 10 - said electromagnet, fixed to the stator, and comprising a

  Il bar made of magnetic material folded in U and a., bobbin-

  ge 12 connected to two pins 13 of connection - a circuit 14 connecting the pins 13 to a source of direct current through a switch

  inverter 16 allowing a fugitive power supply and reversing

winding 12.

  The bar 11 can therefore be temporarily magnetized in the chosen direction and the end of each of its branches 17,18 then alternately presents a north pole N 10 and South. The branches 17, 18 of the bar 11 are arranged both parallel and symmetrically to the axis 4 with their free end substantially in the plane where the N 6 '6 faces.

permanent magnet 6.

  If the power supply is such that the blades facing the permanent magnet 6 and the electromagnet 10 are of opposite polarity (FIG. 2), the resulting reciprocal attraction forces make the magnet permanent remains in place.

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  if said pins are of the same polarity, this results in repulsive forces which, if they do not balance, cause a rotation of one hundred and eighty degrees of the permanent magnet 6

  so that it regains the previous conditions.

  After cutting off the supply of the coil, because of the remanent magnetization of the bar 11 or because its branches 17, 18 are made of magnetic material, the pins of the permanent magnet 6 are held close to the branches 17, 18 and keep

  therefore the last position imposed.

  We will now describe how, according to the invention, without

  very mechanical and / or magnetic means, it is avoided that the rotor 1 is stabilized in a position where the radial line 7 passing through the pins of the permanent magnet 6 merges with that 19

  passing through the poles of the electromagnet 10.

  This situation that would be possible with a permanent magnet

  of known type, would lead, in fact, during the inversion of the

  (Figure 3) to a balance of forces F and FP of repetition.

  sion and would not allow rotation of the permanent magnet 20.

  It is therefore very necessary that at rest, these two lines 7 and 19 are out of phase by a certain angle m A w *

  According to an essential caradiristique of the invention, this result

  tat is obtained by means of contours or cuts 21,22 (FIG. 4) of the permanent magnet 6 in the zones 23, 24, which have the faces 8 and as soon as, relative to the axis of rotation 4, these cuts are diametrically opposed and locate, at different distances, the fractions of zones 23 to 24 a on the one hand, and

  23 b '24 b, on the other hand, delimited by the radial line 7.

  This result is due to the fact that in every magical attraction

  between two bodies, the stable position towards which the

  system is the one that corresponds to the maximum flow.

  Indeed, the flux, and thus the magnetic force, increases when

  that the air gap E 'decreases, assuming lines 7 and 19.

  would be initially confused, fractions 23a, 24 ase-

  would be subject to forces of attraction greater than those

  fractions 23b, 24b, and the difference would therefore create a neck.

  pie of rotation until balance of forces in presence (see

lines of force in Figure 5).

  The phase shift A is proportional to the size of the cut

  and the size of the branches of the electromagnet 10.

  4o By cons, the permanent magnet 6 may have any other form such for example that shown in bold lines in Figure 4 or symbolized in fine lines and hatched on

the same figure 4.

  This cut does not modify the effective position of the electromagnet pins when the magnetic field is reversed.

  that in electromagnet 10 one finds oneself in the same situation

  only if the permanent magnet had been tilted by mechanical and / or magnetic means. Therefore, at each current reversal, the forces F and Ft are unequal and the rotor thus rotates, and this, always in the same direction, namely, towards the cut edge, which distinguishes it from other known bistable elements which always rotate only one hundred and eighty degrees to

  maximum and alternately in one direction and the other.

  It is obvious that without departing from the scope of the invention, this permanent magnet can equip a bistable element whose

  rotor body would be of any shape such as cylindrical

drique, spherical or flat.

  In a preferred embodiment, if only for wind resistance, the rotor body is cylindrical or slightly curved and, according to a feature of the invention,

  The entire magnet is electromagnet 10 and the permanent magnet

  on the one hand to shelter them from clashes, dust, the action of external magnetic fields and, on the other hand, to offer the indications to be displayed, the largest surface area

possible.

  Another characteristic is the bearing 5 of the rotational axis.

  The rotor and therefore the permanent magnet 6 are rigorously positioned relative to the branches 17, 18 of the electromagnet and this by engagement of said branches in holes 25 of the ring 26 carrying the bearing 5. As a result, the air gap E can be reduced to the minimum value t which makes it possible to obtain

  high torque for very low consumption

  tion. The axis of rotation 4, secured to the rotor bit v implement engaged in the bearing 5 to abut on the bottom 26 'of the housing, without the need to provide a retaining element. Indeed,

  by virtue of the law of the maximum flow already set out above, the

  permanent mantle will be solicited towards the interior of the branches of

  the electromagnet and can not escape.

  The support 9 of the electromagnet 10 is formed of a radial plate extending to the axis of rotation and on which

  almost leaning the cantilevered end of the cylindrical body

  than the rotor and this, to perfect the seal.

  This plate may also have a flange 27 or a ring capped by the rotor body to provide guidance of the

  rotor or simply performing a sealing baffle.

  For greater stability, the plate further comprises a base 28 sleeping a good roof bistable element and / or pads 29 which will form positioning wedges

  by pressing against similar elements or other stops.

  For the same purpose, when setting up visu -

  with several rows of elements, the elements of the same row or the same-unit could be

a single support 30.

  Further protecting the bistable elements, in front of the display unit, can be dispc a mask 31 presenting next to each body 2 cutouts 32 of the form of the acronym to be made

  and, for example, circular, which then makes it possible to

  to pose on the bodies of the colored beaches 3 a 3b p of surface

  more important and of different shape.

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Claims (10)

  1. Permanent magnet for a bistable element operable by magnetic means and used in the composition of data display units, which element comprises for this purpose a rotor formed of a body on the outside of which are delimited   two opposing surfaces with different indications.   each other - a permanent magnet fixed in rotation to this rotor to which it is fixed in a position such that the line passing through its north and south faces is substantially radial to the axis of rotation of the rotor, a stator formed of a support and the component below, - an electromagnet fixed to the stator and in a position   such as his North and South Poles are   at the same time symmetrically to the axis of rotation of the rotor   and in the plane in which, together with this rotor, turn   the means for connecting the permanent magnet of the rotor; - a means for connecting the electromagnet to a direct current source allowing a -fugitive power supply and reversible polarity, said permanent magnet being characterized in that, in profile view, said permanent magnet, which has its poles North and   South placed on the same radial line to the axis of rotation, pre-   on its zones which carry said pins, contours which, with respect to said axis of rotation: - on the one hand, are diametrically opposed and - on the other hand, lie at different distances from this axis, the fractions of the aforesaid zones, according to whether they are   one side or the other of the aforementioned radial line.   2. Bistable element for data visualization, including ing:   - a rotor formed of a body on the outside of which are deli-   two opposing surfaces with different indications. from each other,   a permanent magnet secured in rotation with this rotor,   which is fixed in such a position that the line does not   by its North and South pins is substantially radial to the axis of rotation of the rotor - a stator formed of a support and the component hereafter: - an electromagnet fixed to the stator and in a position   as its north and south pits are   both symmetrically to the axis of rotation of the rotor and in the plane o, together with this rotor, rotate the pins of the rotor permanent magnet - a connection means of the electromagnet to a direct current source allowing a fugitive power supply and of reversible polarity, this bistable element being characterized in that   comprises, a permanent magnet according to claim 1.   Bistable element according to claim 2, the body of which   rotor has a shape at least substantially cylindrical, characterized   in that said body completely covers the electromagnet and the permanent magnet.   4. Bistable element according to claim 2 or 3, characterized   in that, in addition to the winding, the electromagnet comprises a   U-shaped magnetic bar with parallel arms   element to the rotation tax of the rotor.   5. bistable element according to claim 4, characterized in that the axis of rotation is carried by a bearing made in a ring rigorously positioned relative to the branches of the electromagnet and by engaging said branches in holes in this ring.   Bistable element according to one of the claims   2 to 5, characterized in that the support is formed of a plate, 2.5 radial to the fictitious extension of the rotation tax, adjoining   the cantilevered end of the rotor body.   Bistable element according to Claim 6, characterized in that   the radial plate has a base.   8. Data display unit, characterized in that   it comprises at least one bistable element, according to any one that claims 2 to 7.   Data display unit according to claim 8,   characterized on its front face, a mas-   than presenting cutouts opposite each body.   Data display unit according to claim 9, characterized in that the cutouts are in the form of the indicia to appear.