US3707690A

US3707690A - Reed switch apparatus

Info

Publication number: US3707690A
Application number: US128796A
Authority: US
Inventors: Michael Sakatos
Original assignee: Sigma Instruments Inc
Current assignee: Sigma Instruments Inc
Priority date: 1971-03-29
Filing date: 1971-03-29
Publication date: 1972-12-26
Anticipated expiration: 1989-12-26

Abstract

Two or more reed switches project through a single magnetic body. Winding means surround the reed switches to make them alternately pick up and drop out. The flux of the magnetized body latches the switches in the conductive state and, when the switch is made to drop out, allows it to remain in the non-conductive state.

Description

United States Patent Sakatos 1451 Dec. 26, 1972 [54] REED SWITCH APPARATUS [72] Inventor: Michael Sakatos, Union, NJ.

[73] Assignee: Sigma Instruments, Inc., Braintree,

Mass.

22 Filed: March 29,1971

21 App1.No.: 128,796

[52] US. Cl ..335/l53 [51] Int. Cl. ..H01h 51/22, HOlh 51/28 [58] Field of Search ..335/l52, 153, 205, 206, 207; I

324/28 R, 28 RS [56] References Cited UNITED STATES PATENTS 2,630,506 Buch ..335/152 2,902,558 9/1959 Peek, Jr ..335/152 FOREIGN PATENTS OR APPLICATIONS 29,821 12/1966 Japan ..335/152 Primary Examiner-Roy N. Envall, Jr. Attorney-Toren and McGeady [57] v ABSTRACT Two or more reed switches project through a single magnetic body. Winding means surround the reed switches to make them alternately pick up and drop out. The flux of the magnetized body latches the switches in the conductive state and, when the switch is made to drop out, allows it to remain in the nonconductive state.

18 Claims, 17 Drawing Figures PATENTED on: 2 6 I372 SHEET 2 OF 5 FIG.4

(S6 LL6 PPG NETWOR LL5 LL6 LL3 LL4 2 C2 C3 C4 C5 C6 'FIG.5

MICHAEL SAKATOS INVENTOR.

BY mam/Mfr? ATTORNEY PATEIITEDnmze 1972 3. 707,690

SHEET 3 [IF 5 I Bm0x-- T Bw PULL IN VALUES BI-- Bp Bp B B Bp 82'' w "Y" w BW B b b Bb -Bw b -Bw B5 Bw Bw Bd i t Bd Bd- DROP OUT VALUES B6 L 8n KN 1 s2 $3 $4 s5 56 B T P EFFECTIV ULL IN VA I I L Bp i I I EFFECTIVE Bb= Be l EFFECTIVE B DROP OUT VALUES Bd w SI S2 S3 84 I6 55 S6 I0 I I I I 1 I I I ID I PATENTEU 05325 3.707.690 sum 5 UF 5 FIG.|6

NETWORK 4o s1 s2 s3 s4 55 S6 N N N N N MICHAEL SAKATOS F I G INVENTOR.

TM Mow/(100? ATTORNEY REED SWITCH APPARATUS BACKGROUND OF THE INVENTION This invention relates to reed-switch apparatuses, particularly apparatuses that include means to actuate and latch reed switches.

A reed switch is usually composed of two magnetizable and conductive flat metal reeds cantilevered inwardly toward each other from glass-to-metal bonds at the ends of a surrounding tubular glass capsule. The reeds also extend axially outward from the bonds of the capsule as conductive leads. The capsule forms an airtight seal around the reeds. The flat reeds are cantilevered so the flat surfaces on their interior ends face each other, but are separated from each other by a gap.

Such a reed switch is actuated by a winding which applies an axial magnetic field. This magnetizes the reeds enough so their interior ends are attracted and moved toward each other across the gap until they pull in, i.e., contact each other. A reduced magnetic latching field is sufficient to hold in the reeds because the poles formed at the reed ends are now very close and exhibit a stronger attractive force than when they are apart. The field must be reduced to a lower value before the switch drops out, i.e., before the magnetic attraction between the interior reed ends is insufficient to overcome the stress forces that drive the reeds into their rest positions.

In the past the magnetic latching field, between the pull-in value and the drop-out value, that has latched the switch in state of conduction into which it was last actuated, has been provided by an adjacent permanent magnet. A winding then effected an alternately aiding or bucking magnetic field to achieve a conductive or non-conductive state in the reed switch.

While such latching magnets are useful for biasing individual switches, they cause problems when a large number of switches must be confined in a small space. Each magnet produces a specific field between the pull-in and drop-out values in each switch. Adjusting the arrangement of such magnets relative to each switch is critical. Magnets for nearby switches distort each others fields. This results in reduced reliability. Where high reliability is demanded, especially where a single winding must pull in or drop out several switches simultaneously, the problem of adjusting the switches within their assembly with the magnet becomes overwhelming. As a result, multiple pole latching relays are rare and difficult to manufacture.

THE INVENTION According to a feature of the invention these advantages are overcome by passing a plurality of reed switches through a single magnetized structure and surrounding the switches with winding means that aid or buck the bodys magnetic flux. According to another feature of the invention, the flux of the body is substantially parallel to the reeds in the switches in the vicinity of the gap. According to another feature of the invention, the structure is a magnetized body.

According to another feature of the invention, the magnetic effect of the body on each reed switch varies with the position of the switch relative to the body. Each of the reed switches extends into the body so as to be subjected to magnetic effects having values between the magnetic effects sufficient to pull in the switch and sufficient to drop it out.

According to another feature of the invention holding means secure each of the switches in place relative to the body.

According to still another feature of the invention the winding means is energizable to aid or buck the magnetic flux in the body sufficiently to pull in or drop out the switches.

According to still another feature of the invention, the switches are inserted into respective openings in the body.

According to yet another feature of the invention, a plurality of switches are inserted into a single opening in the body.

According to still another feature of the invention, the body constitutes a single integral body. According to yet another feature, the integral body is composed of a flexible magnetic rubber-like material. According to yet another feature of the invention the switches include elongated capsules placed side by side to form a radially spaced row through the body. According to another feature, the switches are aligned side by side in a plurality of rows and columns each extending transverse to the length of the switches.

According to still another feature of the invention, additional switch means are inserted into the'body and surrounded by second winding means that aid or buck the magnetic effects of the body to pull in the switches, i.e., make the reeds contact each other, or drop them out, i.e. allow the reeds to lose contact.

According to yet another feature of the invention, the reed switches are adjusted within the body so as to pull-in in a predetermined order as the total magnetic flux density to which the body and the winding means exposes the switches increases.

According to still another feature of the invention, the reed switches are adjusted within the body so as to drop out in a predetermined order as the total magnetic flux density to which the body and the winding means exposes the switches increases.

According to still another feature of the invention, the reed switches form part of a system composed of a network that connects itself through the reed switches to a plurality of circuit means. The network, when it must be connected to the circuit means energizes the reed winding means to pull in the reed switches. When deenergized, the switches are latched. A deenergizing current drops out the reeds to disconnect the network from the circuits. The reed switches may be adjusted to pull in or drop out sequentially in response to a time varying energizing current through the winding means.

Accordingly to another feature of the invention, the apparatus is made by inserting the switches through the body and the winding means, after the winding means and body are mounted on a board, and then adjusting the switches and securing them in place preferably with an adhesive.

According to still another feature of the invention adjustment is made in a jig that energizes the winding means and detects the continuity of each switch. The winding means is energized for pull in and each switch is inserted beyond the point where the indicator shows conduction. The winding means are then deenergized and the indicator checked to determine if it shows continued conduction. The winding means are then reverse energized to check drop out. For sequential pull-ins by the switches, the energizing current of the winding means are adjusted differently for each switch.

According to another feature of the invention the switches are inserted into the body for maximum magnetic effect thereon. The winding means is energized for drop out and the switches withdrawn until after the drop-out occurs. Tests for latching and pull in of each switch follow. Where sequential drop outs may be desired, each switch is adjusted to drop out with a difpanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating a switch reed apparatus embodying features of the invention.

FIG. 2 is a section 2 2 of the apparatus in FIG. 1.

FIG. 3 is a section 3 3 of the apparatus of FIG. 1.

FIG. 4 is a section 4 4 of the apparatus in FIG. 1.

FIG. 5 isa schematic representation of the apparatus of FIG. 1 as used in a system.

FIG. 6 is a graph illustrating the magnetic flux densities required to pull in and drop out the switches of FIG. 1 5.

FIG. 7 is a graph illustrating the subject matter of FIG. 6 with normalized values.

FIG. 8 is a schematic version of FIG. 3 illustrating possible reed positions in the switches of FIG. 3.

FIG. 9 is a schematic representation of another apparatus embodying features of the invention.

FIG. 10 is a sectional representation of the apparatus in FIG. 9.

FIG. 11 is a sectional representation illustrating another apparatus embodying features of the invention.

FIG. 12 is a schematic representation of the apparatus in FIG. 11 with alternate embodiment of the winding means.

FIG. 13 is a partly schematic representation of another apparatus embodying features of the invention.

FIG. 14 is a schematic representation showing another apparatus embodying features of the invention.

FIG. 15 is a schematic representation illustrating another apparatus embodying features of the invention.

FIG. 16 is a schematic representation illustrating a test circuit for testing the apparatus of FIG. 1.

FIG. 17 is a schematic diagram illustrating another embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS:

In FIGS. 1, 2, 3, 4 and 5, six elongated magnetically responsive reed switches S1, S2, S3, S4, S5 and S6 project through six parallel aligned openings 01, 02, 03,

' 04, 05 and 06 in a magnetized flexible rubber" body ever, it may also be composed of a number of windings in different directions, each of which surrounds all of the reed switches. A plastic flat rectangular base 16 to which the body 10 and bobbin 12 are secured, supports the body as well as the bobbin. Conductive outlet leads L1 through L6 emerging axially from one end of each of the respective switches S1 through S6, pass through the base 18 are respective ones of six terminals, T1, T2, T3, T5 and T6, where they are secured to form six respective connector pins, P1, P2, P3, P4, P5 and P6. Similar connector leads LLl through LL6 emerging axially from the other longitudinal ends of the switches 81 through S6, also pass through terminals TT1 through TT6 where they are secured to the base 18 and emerge on the other side of the base 18 as six pins PP1 through PP6. Adhesive rings 20 at the entrance to the openings 01 through 06 secure the reed switches in the body 10 to establish their longitudinal position with respect to the body 10. Similar adhesive material is used at theentrance to the interior of the bobbin 12 to maintain the switches S1 through S6 at their other ends. For clarity the openings 01 to 06 are shown as being large relative to the switch diameters. However, in the preferred embodiment of the invention they are sufficiently small for the body 10 to grip the switches. Since the body 10 is resilient, an interference fit between the switches and the body does not harm the switch capsules. In other embodiments the adhesive is omitted, and in still others other fastening means, such as wedges, are used.

Conductive leads 20 and 22 at the end of the winding 16 and the coil 14 emerge from the coil 14 and project through the base 18 at

terminal points

24 and 26 to emerge from the other side as connector pins 28 and 30. A magnetic shield 32 secured to the top of the bobbin prevents the magnetic field from the coil 14 from affecting, and being affected by, other items of equipment in a system within which the apparatus of FIGS. 1 to 4 is a part.

FIG. 5 illustrates the apparatus of FIGS. 1 to 4 in .a schematically connected manner as part of an electrical system. Here a signal from a network 40 energizes the winding 16 which simultaneously closes each one of the reed switches 81 through S6. The switches 81 through S6 then connect the network 40 with each one of circuits C1 through C6.

Reed switches S1 through S6 are of a type wellknown and have been described extensively in the literature. They are available from applicant's assignee as such. As shown in FIG. 2 and especially in FIG. 5, each reed switch, such as the reed switch S1, is composed of a pair of conductive and somewhat resilient

magnetizable metal reeds

42 and 44 cantilevered at their extreme ends from glass to

metal bonds

46 and 48 at the ends of a surrounding cylindrical and capsulating glass tube 50. The tube 50 and glass-to-

metal bonds

46 and 48 form an airtight seal around the

reeds

42 and 44. The

reeds

44 and 46 extend through the glass-

tometal seals

46 and 48 and terminate in the round conductor leads L1 and LLl. The flat reeds are cantilevered so that flat surfaces on their interior ends face each other but are separated from each other by a gap 52. These opposing separated flat faces at the interior ends of the

reeds

42 and 44 across the gap, are covered with a thin layer of gold or other noble metal to prevent corrosion and insure intimate electrical contact when they meet. When uneffected by a magnetic field, the reeds assume the position shown so as to maintain the gap 52. In the switches, as shown for the switch S1, the reed 42 is shorter than the reed 44. Thus the gap 52 exists closer to one end of the switch than the other. In other embodiments of the invention other types of switches, such as those having gaps near their centers, are used.

The reeds are composed of a magnetic material having comparatively low retentivity, namely a material composed of approximately 51 percent nickel and 49 percent iron.

When a reed switch such as S1 is subjected to a magnetic field with a direction as shown in FIGS. 1 through 5, namely one whose north-south direction extends parallel to the reed, the magnetic flux field of the magnet aligns itself along the magnetic reeds and forms a north-south pole along the gap 52. This produces a i mechanical attraction between the reeds across the gap.

If current through the winding 16 increases, the flux density increases. When the flux density becomes sufficiently strong, the attraction between the reeds across the gap eventually overcomes the inherent resistance of the reeds to distortion from their rest positions. This moves the end faces of the reed toward each other until they contact each other. Such a contact can then close an electrical circuit from a network such as the network 40 to a circuit such as C3. However, as the surrounding magnetic field is reduced, the reeds will not return to their rest positions until the magnetic field falls far below that necessary to attract the reeds into contact. This is so because now that the reeds are in contact, the north-south poles at the reed ends are far closer together than hitherto. Because of this and because the reluctance of the air gap is no longer present, they exhibit far greater mutually attractive forces for any particular magnetic field than when they are apart. As the magnetic field falls even lower, the stressed reeds tend to return to their open position. Eventually the forces of stress within the reed overcome the magnetic attraction and the reeds return to the rest position.

When the reeds are sufficiently attracted to each other to form contact, they are said to be pulled in. This terminology corresponds to the terminology normally used in the relay art. The same relay art furnishes terminology for a return to the rest position which is called dropping out. The magnetic field, that is the flux density, required initially to pull in the switch is called the pull-in flux and the magnetic field, i.e. flux density, to which one must return so that the switch drops out, is called the drop-out flux.

FIG. 6 illustrates pull-in values Bp and drop-out values Bd for switches S1 through S6. These values are measured in terms of flux density B. In the switch S1 if the total flux density rises from zero to the pull-in value illustrated, or any higher value, the switch pulls in. If the flux density drops to or below the drop-out value, the switch drops out. The switches S1 through S6 have different drop-out values and difierent pull-in values because of manufacturing tolerances. The drop-out values and pull-in values are dependent not only upon the resilience of the reeds used, but also the final position that they assume after the glass-to-metal seal has been. applied. Since this glass-to-metal seal usually is applied under conditions of heat, and since glass has a fluidity that cannot be precisely controlled, the gaps in each of the switches may vary and the pull-in values and drop-out values vary. In fact, the pull-in value Bp of one switch such as the switch S2 may be lower than the drop-out value Bd ofa switch such as S5.

In FIGS. 1 through 5 the body 10, at the very center of each of the openings 01 through 06, exhibits a magnetic flux density equal to B-max as shown in FIG. 6. At locations axially away from the center of the opening, the values decrease to B1, B2, B3, B4, B5, etc. The switches S1 through S6 are longitudinally adjusted within the openings so that the flux density at each gap corresponds to some flux density Bb between B-max and B6 which is approximately midway between the respective pull-in values and drop-out values. Thus, for example, the value Bb affecting the switch S1 is approximately between B3 and R4. The value of the flux density Bb of the body on the switch S2 is somewhere between B4 and B5. The values Bb for the switches S3 through S6 are approximately between B3 and B4, and between B1 and B2, and between B3 and B4 respectively. This is shown by the dotted line in FIG. 6. Thus, because of the adjustment of the switches within the body 10, the magnetic effect of the body is such as either to cause the switches to pull in or drop out. The body 10 in effect, latches each of the switches by sub jecting them to the flux Bb, which is a biasing flux. These effective values Bb for each of the switches S1 through S6 are shifted for clarity to the same level Be in FIG. 7. Here the pull-in values and drop-out values of FIG. 6 are arranged about this shifted level Be for the effective value of Bb and may be said to be normalized.

The winding 16 when energized by current in one direction causes a magnetic intensity H which produces an additional magnetic flux density Bw which when added to the respective flux densities Bb on each of the switches S1 through S6, is sufficiently great to exceed the pull-in value of the highest pull-in value. This winding flux value Bw plus magnetic flux density Bb equals Bm for each of the switches shown in FIG. 6. This is shown by the lines Bm. In FIG. 7 because the pull-in values and drop-out values are normalized" about an effective Bb, the value Bw which is always added to the effective value Bb creates a line Bm which is straight.

When the current through the winding 16 is reversed, the magnetic flux density-Bw is created by the winding 16. The value -Bw is added to, i.e. Bw is subtracted from, the value of the flux density Bb of the body and, for each of the switches S1 through S6, forms a total magnetic value Bn shown by the dot-dash line Bn on FIG. 6. FIG. 7 illustrates the same line Bn. However, because here the pull-in values and drop-out values are normalized about the effective Be at each one of the switches, the value Bn is represented by a substantially straight line. The effect of the currents in winding 16 therefore is to shift each of the switches beyond the pull-in value or below the drop-out value. The currents thereby actuate each of the switches.

If each of the switches were not longitudinally adjusted in the body 10, but all were subjected to a magnetic flux density such as B2, then the current creating the value -Bw would not be sufficient to deactivate or drop-out a switch such as S1. On the other hand, if the switches were subjected to a flux of a value such as B3, then the current which produces the magnetic flux density Bw would be unable to pull-in the switch S5.

The operation of the assembly of FIGS. 1 through 5 within a system such as shown in FIG. 5 is as follows:

Initially, the switches S1 through S6 are dropped-out. The body 10 maintains the switches in this drop-out position but applies a latching or biasing magnetic field Bb that is sufficient to maintain the drop-out condition without pulling in the switches. At a given time the network 40 recognizes that it is required to connect itself to each of the circuits C1, C2, C3, C4, C5 and C6. It then produces a current that in turn creates a magnetic flux density Bw or greater which aids the magnetic flux of the body. This magnetic flux density Bm then pulls in each of the switches 81 through S6, thereby closing the circuit from the network 40 to the circuits C1 through C6. In each case the current aiding the body flux density Bb has produced respective north and south poles on the end of each of the reeds in the switches and created sufficient forces between the ends of the reeds at the interior of the switches to overcome the resistance to stress within the reeds. This draws the reeds towards each other. It causes the longer reed to travel through a longer distance through the gap until it contacts the shorter reed. When the current in winding 16 stops, the magnetic flux density falls to the value Bb created by the body 10. Since the switches have been adjusted so that the magnetic field Bb on each switch is between the pull-in value and drop-out value, the reeds, by virtue of the proximity of the ends toward each other, continue to attract each other enough to maintain the reeds pulled in despite the stress to return to their rest positions.

When the network 40 is required to disconnect itself from the circuits Cl through C6, it produces a current which creates a magnetic field Bw that bucks or subtracts from, the magnetic flux density Bb produced by the body 10. The resulting field in each case is then lower than the drop-out value for each of the switches. The switches then drop-out. More specifically, the magnetic flux density of the switches becomes sufficiently low that the attraction, even at the close contact proximity between the ends of the reeds, is not sufficient to overcome the stress produced by the internal strain upon the reeds. The reeds thus open. The gap now exists and no continuous conductive path exists between the network 40 and the circuit Cl through C6.

According to another embodiment the values of Bw and Bw are not identical. They are sufficiently great so that Bb Bw exceeds the pull-in values and Bb Bw is less than the drop-out values.

The assembly of FIGS. 1 through 5 may be used in a system by plugging the pins into suitable sockets furnished in the chassis of a system. They may also be soldered directly.

FIGS. 1 through 5 show the switches in particular rotational orientations. However, the purpose of these orientations are merely to illustrate the gaps in the reeds. The gaps need not be vertical or horizontal because the magnetic field is substantially uniform across any one cross-section of the openings in the body 10. FIG. 8 illustrates other gap orientations within the body 10 for the switches S1 through S6.

FIGS. 1 through 5 illustrate the switches as arranged in a single radial row. According to the embodiment of the invention illustrated in FIG. 9, the switches are not arranged in a single row but are arranged in both radial rows and columns. In FIG. 9 a number of switches extend into the paper through a box-shaped magnetized flexible rubber body 50 corresponding to the body 10. The assembly of FIG. 9 corresponds otherwise to that of FIGS. 1 through 5 and is shown schematically as is the assembly of FIGS. 5 and 8. Here the winding 16 again surrounds all of the switches S10.

FIG. 10 illustrates the assembly of FIG. 9 in the form of a cross-section. Here 18 pins emerge at the rear from a base 52 corresponding to the base 18. These pins are all designated PP10 and correspond to the pins PPl through PP6.

Pins

54 and 56 which emerge from the winding 16, correspond to the

pins

28 and 30 in FIG. 3. The wires here that emerge from the coil are designated 57 and 58 and correspond to wire or

conductors

20 and 22. The openings through which the switches S10 extend are designated 010.

FIGS. 1 through 5 and 8 through 10 illustrate the switches as passing through individual openings through the magnetic bodies. In FIG. 11, the invention is embodied otherwise. Here four switches S12 extend through a single opening 60 in a magnetic body 62 made from the same material as the body 10. Four pins PP12 emerge from the rear of the assembly below a base 64 corresponding to the base 18.

Conductors

66 and 68 corresponding to the

conductors

22 and 20 emerge from the coil hidden from view and mounted on the bobbin 70 and end in

pins

72 and 74 below the base 64. The coil wound on the bobbin 70 contains a winding which surrounds each of the four switches S12. This embodiment of the invention requires slightly more critical spacing than those of FIGS. 1 5 and 8 10 hitherto discussed.

According to another embodiment of the invention, the coil is made up of two windings, each of which applies its own field. The windings may be wound in the same direction and oppositely energized. According to the embodiment illustrated in FIG. 12, the coil is composed of two

windings

76 and 78 wound in opposite directions and energized in the same direction. In FIG. 12 the reed switches S12 are shown schematically to be within the body 62. The structure, except for the windings, is identical to the structure of FIG. 11. Both

windings

76 and 78 are connected to a circuit C12. A single-pole double-throw contactor 79 selects the particular winding to be used for energizing the switches. When the contactor 79 is thrown to the left, the winding 76 is energized and when the contactor is thrown to the right, the winding 78 is energized. FIG. 13 illustrates an arrangement of the switches within a magnetic body 80 with some switches S14 which are placed within a single opening 014 and some switches S16 which have their individual openings 016.

The structure of FIG. 13 corresponds substantially to the structure of FIGS. 1 through 5 except that the body illustrated in FIG. 13 is substituted for the body of FIG. 1.

According to still another embodiment of the invention, separate windings energize or magnetize separate switches within the same, or projecting through the same, magnetic body. As illustrated schematically in FIG. 14, three switches S18 passing through a body 83 corresponding to the body 10, pass through a winding 84 and three other switches S20 pass through a winding 86, as well as the body 82.

FIG. illustrates still another embodiment of the invention. In this schematic showing of an assembly embodying the invention, similar to FIG. 1, switches S22 pass through individual openings 022 in a body 88 corresponding to the body 10, and a winding 90 so as to be energized. The winding 90 may be substituted by two windings operating alternately. The switches S22 form four rows and two columns. A single column of switches S24 extend through individual openings 024 in the body 88 and pass through an energizing winding 92 separate from the winding 90. A column of switches S26 project through a single opening 026 through the body 88 and through an individual winding 94. Four switches S28 project through their individual openings 028 in the body and four other switches S30 project through its opening through a single opening for all of the switches S30, which opening is designated 030. A winding 96 surrounds the portions of the switches S28 and S30 projecting through the body 88.

Each of the assemblies in FIGS. 9 through 15 is adjusted in the same way as the assembly'illustrated in FIGS. .1 through 5. In each case the switches are longitudinally passed through their respective openings and the gap placed in such positions as to cause the magnetic flux from the body to be between the pull-in value and the drop-out value as explained with respect to FIGS. 6 and 7. Each operates when a network such as 40 energizes a winding such as 16 to add to the magnetic field of the body enough magnetic flux to pull in all of the switches. That is to say, it adds sufficient magnetic flux to go beyond the pull-in value of the switch having the highest pull-in value beyond the magnetic flux it receives from the body.

When this current is turned off the magnetic body provides sufficient flux to maintain the switches in their pulled-in condition. That is, the magnetic value provides a biasing magnetic field to latch the switches. This maintains any connection that is made by the leads emerging from the reed switches to a circuit.

When the circuit is to be disconnected from the controlling network, the network reverses the current through the winding on each of the switches, thereby reducing the magnetic flux affecting the switches below the drop-out value so that the switches drop out. This reversal need not be accomplished by the same winding that caused the pull-in. It may be accomplished by another winding in each of these cases. When this current stops the magnetic body again maintains sufficient flux to latch the switches in their open positions.

In the above explanation each of the windings illustrated in FIGS. 8 through 15 may be connected to a different network, as shown in FIG. 15. Thus, each of the sets of switches surrounded by the windings operates independently of the other, while operating in unison with the switches surrounded by the same winding.

The assembly of FIGS. 1 through 5 is manufactured by mounting the body 10, and the coil-carrying bobbin 12 upon the base 18 and then passing the switches S1 through S6 through the openings 01 through 06 that are preformed through the body 10, as well as through the central opening of the bobbin 12. The leads L1 through L6 and LL1 through LL6 are then soldered into the terminals Tl through T6 so they project below the base 18 to form the pin P1 through P6 and PP] through PP6. The leads 20 and 22 are then connected to form the

pins

28 and 30. The entire assembly is electrically connected as shown in FIG. 16. It is placed into a jig for testing.

In its electrical connection the switches S1 through S6 connect across a check battery El through separate lamps H1 through H6. A battery E2 supplies current to the winding 16 through a cross-connect contactor and an adjustable resistor, 102. The cross-connect contactor constitutes a double-pole double-throw switch with extreme terminals cross-connected. When the poles are thrown in one position, the battery current flows through the winding 16 so that the flux of the winding aids the flux created by the body 10. When the switch 100 is thrown into the other position, the winding current creates a flux that bucks the flux of the body 10. The variable resistor 102 adjusts the current in the winding 16 to the values Bw and Bw. These values can, in fact, be changed. Or the positive value Bw can be different from the negative value.

The body 10 is chosen so that its magnetic field is sufficiently strong within the openings 01 through 06 at their centers so as to exceed substantially the highest drop-out value of all the switches S1 through S6. The example shown in FIGS. 6 and 7 shows a maximum flux density that more than performs to this requirement. In fact in FIG. 6 the maximum flux density exceeds all the pull-in values. The resistor 102 is adjusted to provide sufficient current through the winding 10 to increase the maximum flux density Bb exhibited by the body to a value that substantially exceeds the highest of the pullin values of the switches Sl through S6. Since the pullin values and drop-out values of any group of switches may vary considerably, the value of the maximum flux density in the body 10 should be chosen to be comparatively high and the value of the current also be chosen to be comparatively high. This assures reliable operation.

To adjust the switches S1 through S6 the contactor 100 is positioned so that the current through the winding 16 furnishes a flux that aids the flux in the body 10. One of the switches S1 through S6 to be adjusted is then moved longitudinally until the gap is sufficiently affected by the combination of the two fields to light the corresponding lamp. The contactor 100 is then opened to remove the current in the winding 16. The lamp that has been lit should remain lit. The current is then reversed. This should extinguish the lamp. If the lamp is not extinguished by reversal of the current then the switch capsule has been moved too far and the gap extends too far into the opening of the body 10. The switch capsule should then be withdrawn slightly until the lamp extinguishes. Opening of the switch should then leave the lamp extinguished and again reversing the current, should turn on the lamp. If the lamp does not turn on it requires a slight adjustment of the switch capsule into the body. Repeated back and forth testing may be necessary. However, in most cases it is necessary only to move the capsule longitudinally once. When adjusted, the switch capsule is sealed in place by an adhesive. If the fit between the body 10 and the capsule is tight enough, the capsule is simply left in place.

All the switches may be adjusted in similar manner. Under most circumstances, the range of effect of the operating currents upon the switch is sufficiently wide so that the initial adjustment of the capsule to turn on the lamp satisfies all the requirements. The circumstances under which the positioning requirement would not be satisfactory would be if the operating current in the winding produces such a powerful magnetic field that the capsule is not pushed in far enough for the body even to exceed the magnetic flux density required beyond the drop-out value. This will become obvious when the switch 110 is open because the reeds will fail to latch. The capsule can then just be pushed further into or more intimate engagement with the field of the body. A retest to relight the lamp and turn off the current should then allow the lamp to remain lit. The switch is then sealed in place by applying adhesive 20 to it and the body.

The invention may be embodied otherwise. For example, the capsules may be adjusted so that for particular operating currents through the winding 16 different ones of the relays pull in or drop out. This can be accomplished by first setting the contactor 100 to furnish an aiding fluxing. The resistor 102 is then set to provide the lowest pull-in current. An operator then adjusts the switch capsule of the switch, S1 for example, relative to the body 10, by moving the capsule so that the gap begins to enter the opening in the body until the lamp H1 lights. The capsule is then sealed in place by an adhesive between the capsule and the body 10. The resistor 102 is then adjusted to the second lowest desired operating value and the capsule of the switch S2 moved so that its gap begins to enter the opening of the body 10 until lamp H2 lights. Adhesive or a tight fit then holds the capsule of switch S2 in place. The resistor 102 is then set for the third value, at which one of the switches is to pull in and the switch S3 similarly adjusted. Successive switches are then adjusted for successive pull-in values. In each case, after the switch capsule has its position adjusted, the switch 110 is opened to make sure that the switch latches. A reversal current, sufficient to cause all the switches to drop out simultaneously, is then applied. This may be, but is not necessarily equal and opposite to the highest pull-in current.

The assembly of FIGS. 1 through 5 may also be adjusted to provide successive drop-out values with simultaneous pull-in values. In this case, each of the switch capsules is moved so that the gap is located in the strongest portion of the field of the body 10. A forward, or turn-on, current is then applied through the contactor 100 to turn on each of the lamps H1 through H6. The contactor 100 is then opened and the resistor 102 set to provide the lowest current, that is reverse current, for furnishing drop-out. The first switch, such as S1, is then moved so as to withdraw the gap from the concentrated flux in the body until the lamp H1 is extinguished. The contactor 100 is opened to test the latching effect of the body. The lamp should remain extinguished or the switch readjusted. The switch S1 is then sealed in place with the adhesive 20 or a tight fit. The resistor 102 is then adjusted to the second lowest current value that is desired for turning off a switch and the capsule of the switch S2 is withdrawn until the lamp H2 is extinguished. Latching is tested by opening contactor 100 to see if lamp H2 remains extinguished. Adhesive is applied to seal the capsule S2 in place or if the fit is tight enough the capsule is allowed to remain in place.

The resistor 102 is then adjusted for the third current, that is to drop out a switch, and the switch similarly adjusted. As the current values increase by the resistor 102, the switches S4 through S6 are similarly adjusted. The current then is reversed and raised to a value sufficient to pull in all of the switches. This reverse current may be, but need not be, the current that is equal and opposite to the highest drop-out current.

As with the switches S1 and S2, during each of the tests for adjusting the switches S3 through S6 an intermediate test is made by opening the contactor to make such that each one of the switches latches after it has dropped out.

These variable-current pull-in devices and variable current drop-out devices may be used in a system as follows. If the network 40 in FIG. 5 requires that the circuits C1 through C6 be connected sequentially, then the network first applies either a sawtooth wave form to the winding 16 or a step wave form corresponding to the respective pull-in values. With a sawtooth wave form when the current in the winding 16 reaches the value for the switch S1 to pull-in, the reeds of the switch S1 close and connect the circuit C to the network 40. Thereafter, as the current increases successive switches S2, S3, S4, S5 and S6 pull in respective circuits C2, C3, C4, C5 and C6. When the current falls to zero, the switches S1 through S6 remain latched and the circuits C1 through C6 remain connected.

The network 40 simultaneously disconnects the circuits C1 through C6 with a reversal current sufficient to drop out the switch with the drop-out value.

The embodiment of the invention wherein the switches S1 through S6 are actuated to drop out sequentially operates as in FIG. 5 as follows. When the network 40 desires to connect the circuit C1 through C6 to the network 40, it furnishes a pull-in current sufficient to pull in all of the switches S1 through S6. Each of the circuits C1 through C6 is then connected. To disconnect the circuits C1 through C6 sequentially, the network 40 produces a descending or reverse sawtooth or sawtooth step function or a successively descreasing pulse train which sequentially drops out the switches S1 through S6, thereby sequentially disconnecting the circuits C1 through C6. The wave forms necessary for the network 40 to sequentially connect or disconnect the circuits Cl through C6 need not necessarily be either sawtooth wave forms or step wave forms or pulse trains. They may be any time variable waveforms that pull in or drop out any of the switches in a desired time pattern. This lends great flexibility to connecting and disconnecting various numbers of circuits with desired voltage functions.

In FIG. 5 the winding 16 may be substituted by a plurality of windings such as 1 10, 1 12 and 114 as shown in FIG. 17. Here a switch system 116 accomplished the same result as the network 40 for providing, aiding and reversing currents. The currents through the

windings

110, 1 12 and 114 may be equal while the windings may be adjusted in number of turns to provide different magnetic effects. The windings for example may have turns in the

ratios

1, 2 and 4 so that combinations of energized windings produce additive magnetic efiects.

One of the windings may for example be a reverse winding so as to produce reverse effect. In each case a particularly desired sequence of pull-in and drop-out sequences may be obtained.

The switch capsules may be adjusted longitudinally with special tools, especially when the fit between the capsule and the magnetized body is tight.

Strictly speaking, the term latching" refers only to holding the reeds in their contacted state. After they drop out the magnetic field does not actually latch them. They would normally rest in that state. The field has a tendency to make them depart from the unconnected state. However, the term latching has at times been used herein also to refer to the state when, after drop-out current has been applied and then ended, the switches are open.

The invention makes possible a simple compact multiple switch system. The switches are controllable separately, simultaneously and sequentially in a simple manner from a simple source. A simple arrangement allows the apparatus to be manufactured in large quantitites by comparatively unskilled personnel. This saves labor in production. It assures a uniform reliable product that can be used in a number of applications. Moreover, the multiple reed switch apparatus is sturdy and protected from outside influences, both magnetic and mechanical. It also minimizes interference between switches. The magnetic field of one switch does not significantly affect the other. Each switch is effectively independent in operation. A system can leave room for the addition of future switches either by leaving them out altogether, or by locating them without connecting them, while nevertheless operating continuously and without being disturbed by the incorporation.

Aside from these advantages the apparatus according to the invention can be manufactured with components having wide tolerances without affecting the performance. Moreover, the apparatus may be manufactured as modules. They may be manufactured in large quantities at low cost as standard items having a given number of switches. These standard items may be placed in use in applications requiring smaller numbers of switches by simply ignoring the extra switches, without their presence or absence adversely affecting the performance of the system in which they are used. The possibility of small size and low cost makes such use practical and economical despite the presence of extra switches.

While embodiments of the invention have been described in detail, it will be obvious to those skilled in the art that the invention may be embodied otherwise without departing from its spirit and scope.

What is claimed is:

l. A reed switch apparatus, comprising permanent magnet means for producing a constant magnetic field whose flux density varies with the location relative to the permanent magnet means, a plurality of reed switches in the vicinity of said magnet means within the magnetic field, winding means in the vicinity of said reed switches for producing magnetic fields which aid and retard the flux densities at the magnetic field produced by said magnet means, each of said switches having an on condition and an off" condition and having a magnetically sensitive zone, said switches each assuming one of the conditions when a flux density ofa field at its zone is substantially zero, said switches each assuming the other of the conditions when the flux density at its zone arises beyond a given value and retains the other position when the flux density of the filed drops to a lower second value, each of said switches switching to the first position when the flux density of the field drops to a third value below the second value and retaining the one condition when the flux density rises to the second value, each of said switches being movable relative to said magnet means from a location where the field of said permanentmagnet means subjects the zone of the switch to a flux density less than the third value to a location where the zone is subjected to a flux density greater than the second value, said winding means being operative to increase the flux density of the magnetic field at the zone of each switch to and beyond the first value and to decrease the flux density to and below the third value.

2.,An apparatus as in claim 1, wherein said switches are adjustable relative to each other and to said permanent magnet means so as to establish a predetermined order of switching from one condition to the other in response to said winding means.

3. An apparatus as in claim 1, wherein said permanent magnet means includes a body of permanent magnet material and said switches pass through said permanent magnet material.

4. An apparatus as in claim 3, wherein said winding means surrounds said switches.

5. An apparatus as in claim 1, wherein said switches each include a pair of reeds, at least one of which is movable relative to the other so as to contact the other and break contact with the other in response to magnetic fields, said reeds forming a gap relative to each other when contact is broken and a contact area when contact is made, said zone being located at the gap and contact area.

6. An apparatus as in claim 5, wherein one of said reeds is substantially longer than the other, said other reed being relatively movable in comparison with the movable reed.

7. An apparatus as in claim 1, wherein said permanent magnet means includes a permanent magnet, said switches passing through said permanent magnet, said winding means surrounding said switches, said switches being elongated, said magnet extending along each of said switches for a minor portion of the length of each of said switches, said winding means being located along said switches adjacent said magnet and covering a major portion of the length of each of said switches.

8. An apparatus as in claim 7, wherein the zones in each of said switches are located closer to said magnet than said winding means.

9. An apparatus as in claim 1, wherein the switches are off in the one condition so that the switches pull in in switching from the one condition to the other condition and drop out in switching from the other condition to the one condition.

10. An apparatus as in claim 1, wherein said magnet means includes an elongated body, said switches extending transversely to the direction of the elongated body and extending through the body.

11. Apparatus as in claim 10, wherein said body forms a plurality of openings, and wherein each of said reed switches extend through respective ones of the openings.

12. An apparatus as in claim 10, wherein said magnet means includes a body forming an opening, said switches extending through said opening.

13. An apparatus as in claim 10, wherein said body comprises a single integral body of a flexible magnetic rubber-like material.

14. An apparatus as in claim 3, wherein said reed switches are adjusted within said body and the flux pattern of said body so as to pull in a predetermined order as the total magnetic flux density to which said body and said winding means expose said switches increases.

15. An apparatus as in claim 3, wherein said reed switches are adjusted within said body and the flux pattern of said body so as to drop out in a predetermined order, as the total magnetic flux density to which said body and said winding means expose said body, decreases.

16. A system comprising network means, a plurality of circuit means, switch means selectively connecting said network means to said circuit means; said switch means including a permanent magnetic body exhibiting a given magnetic flux, a plurality of reed switches each connecting said network means with one of said circuit means and changeable between a conductive state and a non-conductive state by application of aiding and bucking magnetic fluxes, winding means surrounding said reed switches for adding and subtracting magnetic flux and from the magnetic flux of said magnetic body; said network means including selector means connected to said winding means for applying a current through said winding means, sufficient to change the state of one of said switches, said switch means each being adjustable relative to said body from a position in which said body has substantially no effect on said switch and to a position wherein the field of the magnetic body is sufficient to latch the switches in response to current in said winding means.

17. An apparatus as in claim 1, wherein each of said switches responds to different flux densities to change conditions and wherein the position of each switch is adjusted according to its response.

18. A system as in claim 16, wherein said magnetic body exhibits a flux density according to a pattern which varies about and within said body, wherein said reed switches each pull in when subjected to one flux density and drop out at a lower flux density, the maximum and minimum flux density of the body and said winding means being sufficient to cause said switches to pull in and drop out respectively, said switches being adjusted in the flux pattern of said body so as to be subjected to a flux density between the pull-in and the drop-out densities.

Claims

1. A reed switch apparatus, comprising permanent magnet means for producing a constant magnetic field whose flux density varies with the location relative to the permanent magnet means, a plurality of reed switches in the vicinity of said magnet means within the magnetic field, winding means in the vicinity of said reed switches for producing magnetic fields which aid and retard the flux densities at the magnetic field produced by said magnet means, each of said switches having an ''''on'''' condition and an ''''off'''' condition and having a magnetically sensitive zone, said switches each assuming one of the conditions when a flux density of a field at its zone is substantially zero, said switches each assuming the other of the conditions when the flux density at its zone arises beyond a given value and retains the other position when the flux density of the filed drops to a lower second value, each of said switches switching to the first position when the flux density of the field drops to a third value below the second value and retaining the one condition when the flux density rises to the second value, each of said switches being movable relative to said magnet means from a location where the field of said permanent magnet means subjects the zone of the switch to a flux density less than the third value to a location where the zone is subjected to a flux density greater than the second value, said winding means being operative to increase the flux density of the magnetic field at the zone of each switch to and beyond the first value and to decrease the flux density to and below the third value.

2. An apparatus as in claim 1, wherein said switches are adjustable relative to each other and to said permanent magnet means so as to establish a predetermined order of switching from one condition to the other in response to said winding means.