US3076878A

US3076878A - Switching assembly

Info

Publication number: US3076878A
Application number: US7157A
Authority: US
Inventors: Arthur J Koda
Original assignee: IXYS Integrated Circuits Division Inc
Current assignee: IXYS Integrated Circuits Division Inc; Arris Technology Inc
Priority date: 1960-02-08
Filing date: 1960-02-08
Publication date: 1963-02-05
Anticipated expiration: 1980-02-05
Also published as: FR1280285A; GB964591A; DE1182749B

Description

Feb. 5, 1963 A. J. KoDA swITcHING ASSEMBLY Filed Feb. 8, 1960 JNVENToR. ARTHUR J. Kom BY @0MM/Mmm,

Zzz/e/n mc( Wg ArroeA/E-a/s `3,038,976, are mounted adjacent United States Patent Oiilice aware Fired Feb. s, 1ero, ser. No. 7,157 13 Claims. (Cr. zoo- 93) This invention relates to a switching means and, more particularly, to a new and improved switching means using a sealed switch unit.

In sealed switch units or" the type in which a magnetic armature contained in a sealed dielectric envelope is a1- ternately moved from a center-stable position into engagement with a pair of spaced magnetic terminals, the operate and release current margins of a winding for operating the sealed switch unit are often adjusted by the use of permanent magnetic biasing means. In singleside-stable switch units, a cylindrical permanent magnet is secured to each of the pair of magnetic terminals to extend perpendicularly ou-tward therefrom, and these magnets are then adjusted so that the terminals are biased to opposite polarities by fields of unequal intensity. The magnetic armature is normally held in engagement with one of the terminals by the greater intensity field to provide a break contact, and the relative intensities of the fields produced by the two permanent magnets are adjusted to establish the desired operate or release currents yfor the winding. However, this biasing arrangement requires the use of two permanent magnets, and the strength and the positioning of these magnets also produces large stray fields that interfere with the operate and release current adjustments of adjacent switch units in a plurality unit assembly.

This interaction between the stray fields of the sealed switch units in a plural unit assembly is reduced by alternating the polarities of the biasing means for adjacent switch units in the manner shown Iin detail in the copend- -ing application of Arthur l. Koda, Serial No. 787,536, tiled January 19, 1959, now Patent No. 3,026,390. However, in applcations in which a shielding can is not used with the switching assembly and the individual switch units are positioned immediately adjacent each other, as when a plurality of printed circuit relays of the type shown in the copending application of Arthur I. Koda, Serial No. 731,390, filed April 28, 1958, now Patent No.

each other, the interaction between the biasing magnets becomes appreciable. Dichten, Ir. Patent No. 2,245,391 discloses a center' stable relay that is polarized by a single biasing magnet bridged or -disposed between a pair of magnetic terminals. However, this construction cannot be used in single-side-stable relays and does not permit an accurate adjustment of operate or release currents because the biasing magnet -must normally saturate both of the magnetic terminals.

Accordingly, an object of lthe present invention is to provide a new and improved sealed switch unit.

Another object is to provide a switching assembly in which magnetic interaction between the biasing means for adjacent switch units is prevented.

A `further object is to provide a sealed switch unit including new and improved permanent magnetic biasing means.

Another object is to provide a sealed switch unit including a single basing permanent magnet mounted adjacent one magnetic terminal of the switching unit and spaced `from another magnetic terminal thereof.

A further object is to provide a magnetically biased sealed switch unit in which a permanent magnet having a magnetic axis is positioned adjacent one magnetic terminal and extends toward another magnetic terminal with the axis of the permanent magnet forming an acute angle 3,076,878 Patented Feb. 5, 1963 relative to a line passing through the two magnetic terminals.

A further object is to provide a sealed switch unit in which a single biasing magnet longer than the distance between a pair of generally parallel magnetic terminals is positioned with one pole -face of the permanent magnet disposed adjacent one magnetic terminal and with an opposite pole face spaced from the other magnetic terminal.

A still further object is to provide a switching `assembly in which two parallel magnetic terminals of a sealed switch unit engage opposite sides of a `dielectric panel and in which a permanent biasing magnet is disposed adjacent one of the terminals and is spaced from the other of the terminals by the panel.

A Ifurther object is to provide a switching assembly including new and improved means for mounting a sealed switch unit and a winding therefor on a printed circuit panel.

In accordance with these and many other objects, an embodiment of the invention comprises a dielectric panel having a plurality of spaced openings and carrying a plurality of discrete electrically conductive layers forming a printed circuit pattern. The sealed switch units that are to be mounted on the printed circuit board each comprise an elongated and generally cylindrical dielectric envelope having a common terminal extending from one end thereof and a pair of spaced and generally parallel magnetic terminals extending lfrom the other end thereof. Each of the dielectric envelopes slidably supports a winding for moving a center stable magnetic armature contained within the envelope into alternate engagement with the inner `ends of the pair of magnetic terminals. An assembled switch unit and operating winding is inserted into each of the openings in the printed circuit board so that the engagement of the terminals with the board and the enwith the edges of the opening properly locates the Wlnding and switch unit relative to each other and to the board. In this position, one of -the magnetic terminals engages one side of the board and the other of the magnetic terminals engages the other side of the board at a location laterally -or transversely offset from the one magnetic terminal. One or more of the terminals is suitably secured to the conductive segments to electrically and mechanically connect the switch units to the printed circuit pattern.

In order to provide means for magnetically biasing the center stable armature into normal engagement with one of the magnetic terminals so as to provide a single-sidestable switching construction, each of the sealed switch units is provided with a permanent biasing magnet, preferably rectangular in contiguration, that includes a definite magnetic axis terminating at the opposite ends of the magnet in a pair of pole faces of opposite polarity. The length of the magnet measured along its magnetic axis preferably is greater than the spacing between the pair of magnetic terminals. Each of the permanent magnets extending generally parallel to the printed circuit panel. In this position, the magnetic axis of the biasing magnet forms an acute angle with a line passing through the two magnetic terminals, and the other pole face is spaced from the other magnetic terminal. The interposition of the printed circuit panel between the magnet and the other magnetic terminal serves to maintain a fixed separation between the other pole face and the other magnetic terminal.

With the biasing magnet arranged in .this manner, the inner end of the terminal adjacent the biasing magnet provides a eld of greater intensity so that the adjacent end of the center-stable magnetic armature is normally held in engagement with this magnetic terminal. Since the length of the permanent magnet in the direction of its magnetic axis is preferably greater than the separation between the parallel magnetic terminals and since the other pole face of the biasing magnet is spaced from the other magnetic terminal, the inner end of this other terminal provides a magnetic eld of lesser intensity that does not move the armature away from the more strongly biased terminal. By suitably adjusting the magnetic iield intensity of the biasing magnet and the separation between the other magnetic terminal and the spaced pole face, the opera-te or release current of the switching'unit is adjusted to a desired value. Further, by the elimination of one biasing magnet and because of the fact that the stray flux ield of the single biasing magnet is reduced in intensity, the magnetic interaction between adjacent switch units on the same printed circuit panel or on adjacent printed circuit panels is substantially eliminated. Y

Many other objects and advantages of the present invention will become apparent from considering the following detailed description in conjunction with the drawings in which:

FIG. l is a top plan view in partial section of a printed circuit relay embodying the present invention which illustrates an assembly of a sealed switch unit and a winding in different manners; j

K'FIG. 2 is a sectional view taken along line 2-72 in FIG. l;

FIG. 3 is a sectional view taken along line 3-#3 in FIG. l assuming that a complete switching assembly is shown therein; and

FIG. 4 is a fragmentary perspective view illustrating the relative positions of a biasing magnet and the magnetic terminals of a sealed switch unit.

v Referring now more specifically to FIG. l ofthe drawings, therein is shown a switching assembly, indicated generally as 10, which includes a dielectric panel 12 deiining a plurality of spaced openings 14 and carrying a printed circuit pattern comprising a plurality of individual conductive segments or layers 16. lA sealed switch unit 18 slidably supporting an individual operating winding 20 is disposed in each of the openings 14 with one or more of the terminals of each of the sealed switch units 1:8 engaging and soldered to portions of the printed circuit pattern. The openings 14 conform to the configurations of the windings and thus serve to locate these windings in a proper position relative to the sealed switch units 18.

In order to provide means for rendering each of the vswitching units 18 single-side-stable so that a movable armature normally engages one of a pair of magnetic terminals, each of the sealed switch units 18 is provided with a biasing means comprising a single permanent magnet 22. Each of the magnets 22 provides a denite magnetic axis terminating at opposite ends of the magnet 22 vin pole faces of opposite polarity. |'l`he magnets 22 are mounted on one side of the board or panel 12 with one of the pole faces disposed adjacent one of the magnetic terminals on the switching units 18 and with the magnetic axis extending generally parallel to the dielectric panel 12. Thus, the other pole faces of the magnets 22 are spaced from the other magnetic terminals by intervening portions kof the dielectric panel 12. Because of this disposition of the permanent magnets 22, one of the magnetic terminals of each of the sealed switch units 18 is biased with a eld of a particular polarity that is of greater intensity so that the armature is normally held in engagement with this terminal while the other terminal is biased to an opposite polarity by a field of lesser intensity. By adjusting the position of the spaced magnetic terminal relative to the permanent magnet 22 and by adjusting the strength of the magnet 22, the operate or release currents of the windings 20 can be adjusted to a desired value. Further, the stray flux eld due to the ysingle biasing magnet 22 associated with each ofthe switching units 18 is so small that the magnetic interaction between sealed switch units 18 on the panel 12 or between sealed switch units 18 on adjacent panels 12 is prevented.

Referring now more specifically to the dielectric panel or board 12, this panel is formed of any suitable dielectric material and is provided with a printed circuit pattern on one or both sides thereof by any of the methods or processes well known in the art. The printed circuit pattern consists of the plurality of discrete segments or layers 16 of electrically conductive material, such as copper. Most of these segments include an enlarged end portion 16a formed adjacent an edge 12a which provides a male connector for interconnecting the switching assembly 10 with external circuits. yThe inner ends `o-f most of the segments 16 terminate in enlarged portions 16b or 16C of various configurations that are used to interconnect the components in the switching assembly 1t), such as the sealed switching units 18 or the windings 20, with the printed circuit pattern. ln the assembly 10 shown in FIG. 1 of the drawings, the enlarged portions 16h are used, for instance, to extend electrical connections to the windings 2G, and the enlarged areas 16e are disposed adjacent opposite edges of the elongated openings 14 to provide means for electrically and mechanically interconnecting the switching units 18 with the printed circuit pattern. The dielectric panel 12 also Vincludes a plurality of openings 24 that are u-sed in seof the openings 14 (FIGS.,1 and 2) is provided with a vnarrow opening 26 terminating in a circular opening 28.

The sealed switch units 18 can comprise dry type or mercury switch capsules of any of the types well known in the art. In general, each of the sealed switch units 16 includes a sealed dielectric or glass envelope Si) containing a magnetic and movably mounted armature 32 (FIG. 4) that is electrically connected to a terminal or header 34 extending lfrom the lower end of the envelope 30. A pair o-f generally parallel

magnetic terminals

36 and 38 are carried on the upper end of the dielectric envelope 3i) opposite the terminal 34. The lower ends of the

terminals

36 and 38 are offset inwardly toward each other (FIG. 4) to provide contacts into which the upper end of the armature 32 is alternately moved into engagement under the control of the flux field provided by the winding 2li.

Since the magnetic armature 32 is center-stable, i.e., is normally spaced midway between the lower ends of the

magnetic terminals

36 and 38, the biasing magnet 22 is provided to render the sealed switching unit 1S single-side-stable. ln this condition, the free end of the armature 32 is normally held in engagement with the lower end of the terminal 3b spaced from the terminal 36. When a llux field of a proper orientation is generated by the associated winding 20, the armature is moved out of engagement with the terminal 3S, which provides a break contact, and into engagement with ythe lower end of the terminal 36, which provides a make contact. The termination of the energization of the related winding 2h permits the armature 32 to be restored to its normal position engaging the terminal pin 3S by the ux 4field provided by the permanent magnet 22.

To accomplish this, the permanent magnet 22 preferably is formed' of a rectangular configuration and is provided with a definite magnetic axis or eld orientaltion such that two pole faces 22a and 22h of `opposite polarities are provided at opposite ends of the magnetic axis. The length of the magnet 22 in the direction of the magnetic axis preferably is longer than the distance separating the

terminals

36 and 38. To provide a relatively stron-g ux field of a given polarity adjacent the lower end of the break terminal 33, one of the pole faces, such as the face 22a, is disposed immediately adportion of the magnetic terminal 38, and this magnet is adjusted -so that its magnetic axis forms an acute angle with. a line passing through the

magnetic terminals

36 and 38 transverse to their axes. Because of the angular displacement of the magnetic axis o-f the magnet 22 and because of the fact that the length of this magnet preferably is greater than the distance between the

terminal pins

36 and 38, the second pole face of lopposite polarity, such as the pole face 22b, is spaced from the make terminal 36. Because of the high reluctance air gap separating the terminal pin 36 from the pole face 22h, the intensity of the field provided by the biasing magnet 22 at the lower end of the terminal 38 is substantially greater than the intensity of the magnetic eld of opposite polarity induced at the lower end of the terminal pin 36. The perjaeent the outer or upper -manent magnet 22 is preferably Iformed of a material,

such as Alnico V, so that the `field of the permanent magnet 22 is concentrated at the pole faces 22a and 22b and there is a minimum leakage ilux from the sides of the magnet 22 disposed adjacent the terminal pin 36. It should also be noted that the magneti-c terminal 36 provides a lower reluctance path yfor the ux from the pole `face 22b than a path entirely through air in spite of the air gap separating the pole face 22h and the upper portion of `the terminal 36 so that the lower end of the terminal 36 is magnetically biased to assume a polarity opposite to that of the lower end of the terminal pin 38. Accordingly, the upper end of the armature 32 is magnetically retained in engagement with the lower end of the magnetic terminal 33 to provide the singleside-stable construction.

When the sealed switch 18 is inserted into an axial opening in one of the windings 20, and the assembled switch units and windings 2i are then inserted into each of the openings 14 so that the terminal 34 is positioned within the opening 26 with its lower end disposed within the opening 28. At the upper end of the sealed switch unit is placed in a position resting on the a conductive segment 16 on one side of the panel 12 while the other magnetic terminal 36 is disposed adjacent the lower or other surface of the panel 12 in a position laterally displaced from alignment with the terminal 38. A single bias magnet 22 is then placed on each of the enlarged end portions 16C adjacent the upper ends of the openings 14 (FIG. 1) with the magnetic axis of the magnet extending generally parallel to the panel 12. The iiux iield of the permanent magnet 22 holds this magnet in intimate engagement with the magnetic terminal 38 in a proper position in which the side of the magnet 22 is spaced from the magnetic terminal 36 by the intervening dielectric panel 12. In this position, the axis of the terminal pin 36 is intersected by a line extending perpendicular to the magnetic axis of the magnet 22. One or more panel 12, as by soldering these terminals to the adjacent portions 16e of the conductive segments 16. In addition, the permanent magnet 22 can be soldered to the terminal pins 38 or the enlarged portions 16e or to both of these elements.

In certain instances, it may be desirable to solder the permanent magnets 22 to the terminal pins 38 before assemblying the sealed switch units 18 on the dielectric and biasing magnet 22 are positioned on the board 12, the engagement of the side wall of the permanent magnet 22 with the panel 12 aids in properly locating the

terminals

36 and 38 relative to the panel 12.

Although the permanent magnets 22 can be magnetized to provide magnetic fields of suitable strength and orientation prior to` being mounted adjacent the magnetic terminals 38, this practice may not be desirable because of the possibility of a change in the selected magnetic characteristics during the assemblying operation and because of the fact that the sealed switch units 18 may possess different operating characteristics that must be compensated for by providing biasing magnets of different iield intensities. Accordingly, it is preferable to mount unmagnetized magnetic material which is to form the permanent magnet 22 in a proper position adjacent the magnetic terminal 38 and to then subject the material to a magnetic field of sutlicient strength and than is required to blas the sealed switch unit 18 for single-side-stable operation. This magnet is then subjected to an alternating current eld which reduces the intensity of its magnetic field. During the application of the alternating current signals, test equipment connected to the sealed switch unit 18 indicates the operating characteristic of the unit 18 so that a desired release or operate margin can be established. When the desired operating characteristic is established, the application of the alternating current eld to the permaof the field of the permanent magnet 22 can be adjusted in the manner described above to control the operate and release characteristics of the sealed switch unit 18, the angular deilection of the permanent magnet about the axis of the magnetic terminal 38, the length of the permanent magnet 22 in the direction of its magnetic axis, and the consequent spacing of the pole face 22b from the magnetic terminal 36 can also be varied in order to control the operating characteristics of the sealed switch unit 18.

If desired, the windings Ztl can be secured in proper positions on the dielectric panel 12 and this panel, the conductive segments 16, and the other components car ried on the board 12 can be electrically insulated and protected from the atmosphere by bonding a pair of assembly 10.

In the normal condition of the switching assembly 10, the biasing magnets 22 magnetically retain the magnetic armatures 32 in engagement with the lower ends of the energizing signal is applied to one or ings 2t) over the conductive segments 16 connected thereo develop ilux elds which induce a polarity ends of the magnetic armatures 32 that is opposite to the polarity of the lower ends of the terminals 38, the upper ends of the magnetic armatures 32 are repelled from the lower ends of the terminals 38 and are attracted toward the lower ends of the terminals 36 so that the armatures 32 engage the terminals 36 to open lthe break contacts and to close the make contacts. When the energization of the coils 20` is terminated and the ux Vfields collapse, the intensity of the fields induced at the lower ends of the terminals 38 and the resiliency of the armatures transfer the armatures 32 from positions engaging the lower ends of the terminals 36 to ones in which these armatures engage the lower ends of the terminals 3S. Thus, the make contacts are opened and the break contacts are closed, and the a position in which said magnetic axis extends .sealed switch units 1S are restored to their normal condition.

Although the present invention has been described with reference to a -single illustrative embodiment thereof, it should be understood that numerous other modiiications and embodiments can be devised by those skilled Iin the art that will fall within the spirit and scope of the principles of this invention.

What is claimed and desired to be secured by Letters Patent of the United States is:

l. A switching unit comprising a sealed switch unit having a pair of magnetic terminals carried thereon, a permanent magnet having a pair of spaced pole faces at opposite ends of a magnetic axis, and means mounting said permanent magnet for magnetically biasing the two magnetic terminals with fields of opposite polarity with one of said pole faces adjacent one of said magnetic terminals and with a straight line connecting said pole faces extending generally transverse to said one terminal and outwardly at an acute angle from a line connecting said magnetic terminals so that the other pole face is spaced from the other terminal to apply diiferent degrees of magnetic bias to the two magnetic terminals.

2. A switching unit comprising a dielectric envelope, a pair of generally parallel magnetic terminals spaced from each other by a given distance, a permanent magnet having a pair of pole faces spaced from each other a distance along a magnetic axis of said permanent magnet that is greater than said given distance, and means positioning said permanent magnet for magnetically biasing the two magnetic terminals with iields of opposite polarity with one pole face adjacent one of said terminals and with said magnetic axis extending toward said other terminal at an acute angle relative to a line passing through both of said terminals so that said other pole face is spaced from said other terminal to apply different degrees of magnetic bias to the two magnetic terminals,

Y3. A switching unit comprising a sealed dielectric envelope, a movable magnetic armature in said envelope, a pair of magnetic terminals carried on said envelope and including a lirst portion positioned adjacent one end of said armature and a second portion disposed outside of said envelope, said magnetic armature having a portion disposed between the first portions of the pair of magnetic terminals and being free of mechanical stresses sufficient to bias said armature into engagement with either of said magnetic terminals, a permanent magnet having two pole faces positioned at opposite ends of a magnetic axis, and means securing one pole face of said permanent magnet to one of said second portions with said magnetic axis extending generally transverse to said one second portion and forming an acute angle with a line passing through both of said second portions, said other pole face of said permanent magnet being spaced from said other second portion, the two terminals being magnetically biased by said magnet with fields of opposite polarity.

4. A switching unit comprising a sealed dielectric envelope, a pair of magnetic terminals carried on said envelope and extending along a pair of spaced parallel lines, a magnetic armature contained within said envelope and including a portion disposed between and movable relative to said magnetic terminals, said magnetic armature being free of mechanical stresses suicient to bias said portion into engagement with either of said pair of magnetic terminals, a permanent magnet having a pair of pole faces connected by a magnetic axis, and means mounting said permanent magnet for magnetically biasing the two magnetic terminals with iields of opposite polarity with one pole face adjacent one of said magnetic terminals and spaced from the other of said magnetic terminals, said permanent magnet being mounted in generally transverse to the axis of said one magnetic terminal and in lwhich a line perpendicular to said magnetic axis in- 'tersectsthe axis of said other magnetic terminal.

5. A switching assembly comprising a dielectric panel having an opening, a sealed switch unit having a pair of spaced magnetic terminals, means mounting said switch unit in said opening with the terminals disposed on opposite sides of said panel, a permanent magnet having a pair of opposite pole faces at opposite ends of a magnetic axis, and means mounting said permanent magnet on said panel for magnetically biasing the two magnetic terminals with fields of opposite polarity with one of said pole faces adjacent one of said terminals and with said magnetic axis extending substantially parallel to said panel.

6. A switching assembly comprising a dielectric panel having an opening therein and at least one electrically conductive layer disposedadjacent an edge of said opening, a sealed switch unit having at least a pair of spaced magnetic terminals at one end thereof, said sealed switch unit being positioned in said opening with one of said terminals secured to said layer on one side of said panel and with the other terminal positioned on the other side of said panel, and a permanent magnet mounted adjacent one of said terminals and spaced from the other of said terminals by said panel, with the two terminals magnetically biased by said magnet with elds of opposite polarity.

7 A switching assembly comprising a dielectric panel having an opening therein and at least one electrically conductive layer on at least one side of said panel disposed adjacent an edge of said opening, a sealed switch unit having a pair of magnetic terminals at one end thereof, said sealed switch unit being disposed in said opening with one of said terminals engaging said layer on one side of said panel and the other of said terminals positioned on the other side of said panel spaced laterally from said one terminal, means connecting said one terminal to said layer, and a permanent magnet mounted on said one side of said panel adjacent said one terminal and extending over said other terminal but spaced therefrom by said panel, with the two terminals magnetically biased by said magnet with fields of opposite polarity.

8. A switching assembly comprising a dielectric panel having an opening, a sealed switch unit having a pair of generally parallel and spaced magnetic terminals, said sealed switch unit being mounted in said opening with one of said terminals positioned on one side of said panel and the other of said terminals positioned on the other side of said panel, a permanent magnet having a pair of pole faces connected by a magnetic axis, and means mounting said permanent magnet on said panel for magnetically biasing the two magnetic terminals with fields of opposite polarity with one of said pole faces adjacent one of said terminals and so that a line perpendicular to said magnetic axis intersects the other of said terminals.

`9. A switching assembly comprising a dielectric panel having a plurality of spaced openings, a plurality of electrically conductive layers secured to spaced portionsof said panel and including portions disposed adjacent said openings, a plurality of sealed switch units each comprising a dielectric envelope having at least two spaced terminals, each of said switch units being disposed in one of said openings with the terminals secured to said portions, and ya winding disposed in each of said openings and carried on the dielectric envelope of the sealed switch unit, said openings generally conforming to the contiguration of the windings to locate said windings in proper positions on said sealed switch units.

l0. A switching assembly comprising a dielectrical panel havinga plurality of spaced openings, a plurality of electrically conductive layers secured to spaced portions of said panel and including portions disposed adjacent said openings, a plurality of sealed switch units each comprising a dielectric envelope having at least two spaced magnetic terminals projecting from one end of said envelope, permanent magnetic means secured to one of each pair of said terminals and disposed adjacent but spaced from the other one of the terminals in each pair thereof to magnetically bias the two terminals of each pair with fields of opposite polarity, each of said switch units being disposed in one of said openings with at least one of the terminals secured to one of said portions, and a winding disposed in each of said openings and carried on the dielectric envelope of the sealed switch unit, said openings generally conforming to the coniiguration of the windings to locate said windings in proper positions on said sealed switch units.

11. The switchingy assembly set forth in claim including a dielectric material covering each side of said panel to electrically and mechanically protect said switching assembly and to electrically insulate said permanent magnetic means.

12. A switching assembly comprising a sealed and elongated dielectric envelope, a pair of magnetic terminals carried on one end of said envelope and each including a first portion disposed within the envelope and a second portion projecting out of said envelope, said second portions extending generally parallel to each other and being spaced from each other a given distance, a movable magnetic armature supported from the other end of said envelope and having a portion disposed between the first portions of the pair of magnetic terminals, said magnetic armature being free of mechanical stress suticient to bias said armature into engagement with either of said magnetic terminals, permanent magnet means having two pole faces of opposite polarity positioned at opposite ends of a magnetic axis, the length of said permanent magnet means along a straight line connecting the pole faces being greater than said given distance, and means securing one pole face of said permanent magnet means adjacent one of said second portions with said straight line extending transverse to said one second portion and forming an acute angle with a line passing through both of said second portions so that the other pole face of said permanent magnet means is spaced from said other second portion, the two terminals being magnetically biased by said magnet with fields of opposite polarity.

13. A switching assembly comprising a dielectric panel having an elongated opening therein, at least one electrically conductive layer having a portion disposed adjacent one end of said opening, a sealed switch unit including a pair of spaced magnetic terminals at one end thereof, said sealed switch being disposed in said opening with said pair of magnetic terminals disposed with at least one of said pair of magnetic terminals disposed ad- Jiacent said portion of the electrically conductive layer, means connecting said one magnetic terminal to the adjacent portion of the electrically conductive layer, and permanent magnet means for biasing the two terminals of said pair with fields of opposite polarity and including a pair or" opposite pole faces disposed at opposite ends of a magnetic axis, the length of Said permanent magnet means in the direction of said magnetic axis being greater than the distance between said pair of magnetic terminals, said permanent magnet means being connected to one ot the magnetic terminals with one of the pole faces adjacent this terminal and with the other pole face spaced from the other magnetic terminal, the magnetic axis of said permanent magnet means extending generally transverse to the connected one of the magnetic terminals and forming an acute angle with the plane passing through the pair of magnetic terminals.

References Cited in the file of this patent UNITED STATES PATENTS 2,821,597 Germanton et al. Jan. 28, 1958 2,823,360 Jones Feb. 11, 1958 2,877,315 Oliver Mar. l0, 1959 2,898,422 Peek Aug. 4, 1959 2,907,846 Wilhelm Oct. 6, 1959 2,922,857 Peek Jan. 26, 1960 2,929,895 Shebanow Mar. 22, 1960 2,957,961 Juptner Oct. 25, 1960 2,999,915 Peiderer et al Sept. 12, 1961 3,002,067 Baldwin et al. Sept. 26, 1961

Claims

1. A SWITCHING UNIT COMPRISING A SEALED SWITCH UNIT HAVING A PAIR OF MAGNETIC TERMINALS CARRIED THEREON, A PERMANENT MAGNET HAVING A PAIR OF SPACED POLE FACES AT OPPOSITE ENDS OF A MAGNETIC AXIS, AND MEANS MOUNTING SAID PERMANENT MAGNET FOR MAGNETICALLY BIASING THE TWO MAGNETIC TERMINALS WITH FIELDS OF OPPOSITE POLARITY WITH ONE OF SAID POLE FACES ADJACENT ONE OF SAID MAGNETIC TERMINALS AND WITH A STRAIGHT LINE CONNECTING SAID POLE FACES EXTENDING GENERALLY TRANSVERSE TO SAID ONE TERMINAL AND OUTWARDLY AT AN ACUTE ANGLE FROM A LINE CONNECTING SAID MAGNETIC TERMINALS SO THAT THE OTHER POLE FACE IS SPACED FROM THE OTHER TERMINAL TO APPLY DIFFERENT DEGREES OF MAGNETIC BIAS TO THE TWO MAGNETIC TERMINALS.