US3217122A

US3217122A - Bi-stable reed relay

Info

Publication number: US3217122A
Application number: US149349A
Authority: US
Inventors: Joseph M Bernstein
Original assignee: Automatic Electric Laboratories Inc
Current assignee: Automatic Electric Laboratories Inc
Priority date: 1961-11-01
Filing date: 1961-11-01
Publication date: 1965-11-09
Anticipated expiration: 1982-11-09

Description

Nov. 9, 1965 Filed Nov. 1, 1961 J. M. BERNSTEIN 3,217,122

BISTABLE REED RELAY 2 SheetsSheet l to U 6% 21 FIG.1 I 14 H m is "2 FIG. 2

X I 20 s g N 5') 1 Vi SJZ I4 17 j II' I 22V l8' 1' FIG. 3 20' 6' g N 51/) 1 VI 5 $4. l4, :2 III 2| j INVENTOR. JOSEPH M BERNSTEIN ATTY.

1965 J. M. BERNSTEIN 3,217,122

BI-STABLE REED RELAY IN VEN TOR. JOSEPH M. BERNSTEIN ATTY.

United States Patent 3,217,122 BI-STABLE REED RELAY Joseph M. Bernstein, Bensenville, Ill., assignor to Automatic Electric Laboratories, Inc., Northlake, 11]., a corporation of Delaware Filed Nov. 1, 1961, Ser. No. 149,349 Claims. (Cl. 200-87) This invention relates to electromagnetic switching devices known in the art as reed relays. In addition, this invention relates to electrical switching networks or matrices utilizing these devices.

The encapsulated reed relays of the prior art, while otherwise satisfactory, have the drawback that their magnetic circuit is of relatively high reluctance. A reed relay according to the present invention reduces this by the use of a gapped magnetic core for actuating the reed relay which extends through the walls of the capsule to form an essentially complete magnetic path. Accordingly, the relay of the present invention provides a number of significant advantages. For instances, the amount of exciting current necessary to actuate the switch is materially reduced. Secondly, if the aforementioned magnetic core is constructed from such magnetic materials as ferrite the reed relay may be used to act as a magnetic memory element. Thus, according to the invention, magnetic core memory techniques are applied to electromechanical switches of the reed relay type.

One object of the invention is to provide a reed relay whose sensitivity is improved upon by a reduction of the leakage flux, thus, reducing magnetic interaction when a plurality of such relays are constructed in a matrix.

Another object of the invention is to provide an improved reed relay which is kept actuated with no power consumption.

Still another object of the invention is to provide a reed relay which can be actuated by a signal of extremely short duration, that is a duration suificient only to change the state of the core.

And still another object of the invention is to provide a matrix of reed relay-s having an improved magnetic circuit, wherein the relays are selectively energized by a coincidence select-ion circuit.

A still further object of the invention is to provide such a matrix of reed relays wherein the relays are interconnected in a word-oriented selection circuit.

With these objects in mind the embodiment of the invention shown herein features a vacuum sealed, polarized, bi-stable reed relay which is magnetically actuated. The magnetic circuit consists of a horseshoe-shaped gapped ferrite core at least the poles of which defining the gap are encapsulated inside of, and supported by, an evacuated glass capsule or the like. On one of the contact springs is placed a permanent magnet which is so positioned that it may be drawn perpendicularly towards the gap of the pole faces between the legs of the horseshoe. With the permanent magnet so positioned the gap length is materially shortened and thus the performance of the magnetic core is similar to that of a conventional toroidal ferrite core. In addition the permanent magnet, in view of the residual flux in the core, will maintain its position until a release signal actuates the ferrite core.

Further objects and features of the invention will become apparent from the following detailed description of an embodiment taken with the accompanying drawings of which:

FIG. 1 shows a cross-sectional side view of the electromagnetic reed relay.

FIG. 2 illustrates a cross-sectional top view of the reed relay shown in FIG. 1.

FIG. 3 shows a cross-sectional top view of a modification to the reed relay shown in FIG. 1 and FIG. 2.

ice

FIG. 4 discloses a side View of an alternative contact arrangement for the reed relays shown in FIG. 1 or FIG. 3.

FIG. 5 illustrates another packaging arrangement for the reed relay of this invention.

FIG. 6 illustrates yet another packaging arrangement for the reed relay of this invention.

FIG. 7 is a schematic view which illustrates a matrix of reed relays of the type of this invention wherein these relays are selectively energized by a coincidence selection circuit.

FIG. 8 is a schematic view which illustrates a matrix of reed relays of this invention wherein these relays are interconnected in a word-oriented selection circuit.

Referring now to FIGS. 1 and 2 which illustrate crosssectional orthogonal views of the preferred embodiment of the invention claimed in this application. As can be noted from an examination of these two figures, the relay assembly is contained in a tubular envelope 1, or capsule, preferably constructed of glass. Inserted through opposite ends of the glass capsule are two cantilevered spring contacts 5 and 6, and also inserted'through one end is a mag netic core 2 which is in the shape of an elongated horseshoe. A permanent magnet 9 is mounted on contact spring 6. A number of coils are wound on the closed end portion 20 of the magnetic core 2 which is outside of one end of the glass capsule.

The tubular capsule 1 must be constructed from a nonmagnetic and non-conductive material. While it is preferable that this capsule be constructed of glass, other amorphous or solid materials which are non-magnetic and nonconductive may also be used. Whatever the material used, it must be capable of forming a hermetically sealed unit since it is preferable that the capsule be evacuated of air and backfilled With a gas to reduce contact erosion or contamination. This requires that the contact springs 5 and 6 and the

core legs

18 and 19 be bonded to the glass, or other material, with air-tight seals. Specifically, contact spring 5 must be sealed at opening 14, contact spring 6 must be sealed at opening 15, while core leg 18 must be sealed at opening 16, and core leg 19, must be sealed at opening 17.

Magnetic core 2, which is in the shape of an elongated horseshoe, is preferably fabricated from a ferrite material. This ferrite material must have magnetic characteristics such that a core constructed from this ferrite material would exhibit essentially a square hysteresis curve. As reported in the literature, a small air gap inserted in such a ferrite core will not materially affect the square hysteresis curve characteristics of the core; see for instance the article published in the Journal of Applied Physics, volume 29, July 1958, titled Switching in Rectangular Looped Ferrite Containing Air Gaps by U. P. Gianola. As will be discussed in detail subsequently, this physical phenomenon is utilized in the operation of the reed relay of this invention. In this connection it is to be noted that the gap in the core must be made as small as possible, i.e., the separation between pole faces 3 and 4 of magnetic core 2 should be as small as possible.

The cantilevered contact springs 5 and 6 are the electrical switching elements of the reed relay. Contact spring 5 is anchored and supported at opening 14 in one end of the glass capsule, while contact spring 6 is anchored and supported at opening 15 in the other end of the glass capsule. Contact spring 6 must be appropriately adjusted and positioned with respect to the magnetic core 2, which is also embedded in glass capsule 1, in such a manner that upon initiating of attractive magnetic forces between permanent magnet 9 and pole faces 3 and 4 of the ferrite core, the permanent magnet 9 on contact spring 6 is drawn up vertically towards the air gap between the pole faces. Since permanent magnet 9 is to be rigidly fastened to contact spring 6, the magnetic force on the permanent magnet causes contact spring 6 to deflect so that contact is made between it and contact spring 5 at contact surfaces 7 and 8. The contact pressure exerted by spring 6 on spring 5 at surfaces 7 and 8 causes contact spring 5 to partially deflect upward as would be viewed in FIG. 1 so that good electrical contact is made at contact surfaces '7 and 8.

Contact springs 5 and 6 should be constructed from material which is a good electrical conductor. There is no requirement that this material be magnetic. The fact that there is no requirement that the contact spring material be constructed of magnetic material represents a significant departure from most of the other reed relays in the prior art. The contact spring material should have good mechanical contact characteristics, such as light weight, high resiliency, give little evidence of fatigue even after millions of operations, and be capable of forming a hermetical seal with the glass at the two ends of the capsule. Berylliumcopper and Phosphor bronze are perhaps the most suitable materials for this application.

To reduce the contact resistance between contact surfaces 7 and 8, and hence, to reduce the amount of microphonic noise introduced into the electrical circuit which is switched by the reed relay, the contact springs at contact surfaces 7 and 8 may be gold plated. In addition, for applications wherein high conductivity is mandatory, the entire surfaces of contact springs 5 and 6 may be gold plated.

In the operation of this reed relay permanent magnet 9 is preferably wholly or partially inserted into the air gap between pole faces 3 and 4 of ferrite core 2. As mentioned previously, permanent magnet 9 is rigidly fastened to contact spring 6 so that upon operation of the magnetic forces between permanent magnet 9 and pole faces 3 and 4 contact spring 6 is deflected to make contact with contact spring 5. While permanent magnet 9 may be fastened to contact spring 6 in a great variety Of ways, it is preferable that some form of mechanical fastening be used.

Permanent magnet 9 should be fabricated from some form of ceramic magnet material. This choice of material is dictated by the following considerations. First of all, it is desirable that the material produce a minimum of outgassing so that contact erosion or contamination is held to an absolute minimum as discussed for the ferrite core 2. Ceramic magnetic materials produce significantly less outgassing than conventional steel or cobalt-nickel permanent magnets. Secondly, it is desirable that the permanent magnet 9 have as little a mass as possible so as to increase the sensitivity and switching speed of the reed relay. The ceramic magnetic materials are significantly lighter than conventional steel or cobalt-nickel magnets.

As mentioned previously, a number of coils may be wound on the arc portion 20 of the ferrite core which is outside of the glass capsule. In FIG. 2 four such windings are shown. For the purposes of this discussion, coils 1t and 13 will be denoted as the actuating coils. Coil 11 denoted as the sense winding, while coil 12 is denoted as the inhibit winding. That is, when currents of the proper polarity and amplitude are passed through coils and 13, a magnetic flux is produced in ferrite core 2 which is suflicient to cause contact spring 6 to deflect mechanically so that contact with contact spring 5 is achieved. Sense coil 11 is used to determine the state of the remanent flux in the ferrite core. Inhibit winding 13 has the dual function of either producing a bucking flux to that produced by the actuating coils 10 and 13 so that the relay is not operated, or to produce a small change in the flux in the ferrite core 2 so that the state of the flux in the ferrite core may be ascertained by means of circuitry connected to sense winding 11.

In considering the method of operation of the reed relay device illustrated in FIG. 1 and FIG. 2, it will be assumed that initially the reed relay is in the inoperative state, i.e., switch contacts 5 and 6 are open as illustrated in FIG. 1. It is also assumed that permanent magnet 9 is magnetized so that its north pole is located at the top of magnet 9 as shown in FIG. 2, while its south pole is located at the bottom of the magnet as shown in FIG. 2. When the reed relay is in this inoperative state, the remanent flux in the ferrite core 2 is oriented so that pole face 3 represents the north pole of the core, while pole face 4- represents the south pole of the core. The magnetic forces between the aligned north poles and south poles of the penmanent magnet 9 and the ferrite core 2, respectively, with these as sumed conditions cause contact spring 6 to be forced away from contact spring 5.

As mentioned previously, the reed relay of this invention is actuated by passage of current through

coils

10 and 13, provided that a current is not simultaneously passed through inhibit winding 12. It is preferable that the amplitude of the current pass through either of

coils

10 and 13 alone be insuflicient to actuate the device. That is, it is preferably that the relay be actuated in a coincident manner by energizing both

coils

10 and 13 simultaneously with currents of appropriate polarity and amplitude. The magnetomotive forces produced by the coincident passage of current through

coils

10 and 13 must be suflicient to saturate ferrite core 2 in the opposite direction to that of the assumed initial remanent flux.

As mentioned previously, the core 2 is to be constructed from ferrite material having essentially a square hysteresis curve. Furthermore, the small air gap between pole faces 3 and 4 will not materially effect the characteristics of this hysteresis curve. Thus, when ferrite core 2 has been saturated in the opposite direction to that of the original remanent flux, the flux in the core will remain at essentially the same value even though the actuating currents pass through

coils

10 and 13 are eliminated. In other words, as soon as the ferrite core has been switched from the original remanent flux state to the new flux state, the current energizing coils It and 13 need no longer be present. Since the magnetic flux in a ferrite core can be switched from one state to another in an extremely short interval of time, in the order of microseconds, the actuating eurrent signals to

coils

10 and 13 may be in the form of short current pulses.

When the magnetic flux in ferrite core 2 is switched from the original remanent flux state to saturation in the opposite direction, pole face 3 of ferrite core 2 now becomes the south pole of the core while pole face 4 now becomes the north pole of the core. After the actuating currents through

coils

10 and 13 are no longer present, the flux in the ferrite core will remain at a new value which is almost equal to the saturation value of the flux due to the essentially square hysteresis curve of the airgapped ferrite core. The magnetic forces between the aligned north pole of permanent magnet 9 and the south pole now located on pole face 3 due to this new state of remanent flux in the ferrite core, and the south pole of the permanent magnet 9 and the north pole of the core now located on pole face 4 causes the permanent magnet 9 to be drawn towards the air gap between pole faces 3 and 4 of ferrite core 2. This of course, forces contact spring 6 to deflect and thereby make contact with contact spring 5 at contact surfaces '7 and 3, thus closing the electrical circuit connected to contact springs 5 and 6. It is extremely important to note that the magnetic force causing the closure of contact springs 5 and 6 is that due to the inter-action of the flux from the permanent magnet 9 and the remanent flux in the ferrite core 2. This face distinguishes the reed relay of this invention from all of the reed relays of the prior art. In these prior art reed relays the magnetic flux closing the contact springs is generated by the current passage through the energizing coil of the reed relay. It is also to be noted that in the reed relay of this invention contact spring 6 will remain in contact with contact spring 5 until the remanent flux in ferrite core 2 is switched to the other remanent flux state. In the reed relays of the prior art this maintenance or holding of the contacts in the closed position is achieved by means of a permanent and contact springs made of magnetic material.

It is also important to note that the reed relay of this invention must be designed so that the magnetic flux of ferrite core 2 is not sutficient to change the orientation of magnetic poles of permanent magnet 9. That is the coercivity of permanent magnet 9 must be greater than the induced magnetomotive forceof the flux across the air gap in ferrite core 2. In like manner, the magnetomotive force generated by permanent magnet 9 in ferrite core 2 must be insufficient to switch the magnetic flux in the ferrite core from the inoperative state to the operative state or from the operative state to the inoperative state. In addition, the magnetic force resulting from the interaction between the flux of permanent magnet 9 and the remanent flux of ferrite core 2 acting upon permanent magnet 9 must be sufficient to exert a sufiicient pressure between contact spring 6 and contact spring 5 at contact surfaces 7 and 8 to insure a good electrical contact.

To release the reed relay of this invention, current pulses of opposite polarity to that which actuated the reed relay must be passed through coils '10 and 13 simultaneously. The magnetomotive force in the ferrite core 2 resulting from this passage of current will reverse the magnetic flux in the core to saturation in the opposite direction. This will cause a north magnetic pole to be formed on pole face 3 of the ferrite core while a south magnetic pole will form on pole face 4. Since the north pole of permanent magnet 9 will be adjacent to the pole face 3 of the ferrite core while the south magnetic pole of permanent magnet 9 will be adjacent to the south pole of pole face 4, the resulting magnetic force on the permanent magnet and hence on contact spring 6 will force the permanent magnet and contact spring 6 away from the air gap between pole faces 3 and 4 of the ferrite core. As is the case to operate the reed relay, the current signals to

coils

10 and 13 to release the reed relay need only be present during the switching of the magnetic flux in the ferrite core. Since the switching of magnetic flux in the ferrite core can be accomplished in a very short interval of time, in the order of a few microseconds, the release current signals can be in the form of short current pulses. The repulsive force between permanent magnet 9 and the pole faces of ferrite core 2 is thus a result of the interaction of the flux from the permanent magnet 9 and the remanent flux from the pole faces of ferrite core 2.

While the operation of the reed relay and the release of the reed relay are accomplished in the same manner, there is a clear distinction in the magnetic circuit operation between the two states. That is, when the relay is to be switched from the inoperated state to the operated state, permanent magnet 9 is away from the air gap between the pole faces of the ferrite core; when the reed relay is switched from the operated state to the inoperated state, permanent magnet 9 is near the air gap between the pole faces of the ferrite core. With permanent magnet 9 not in the air gap between the pole faces, the ferrite core will have essentially a square hysteresis curve characteristic as discussed previously. However, when permanent magnet 9 is in the air gap, the hysteresis curve for the composite magnetic circuit will be asymmetrical with regard to the B and H axis. Since the flux of permanent magnet 9 Will tend to opose the change of flux in the ferrite core when the ferrite core is to be switched from the operative condition to the inoperative condition, a greater magnetomotive force will be necessary to switch the core from the operative state to the inoperative state than vice versa.

It should be noted that the time required for switching the flux state in the ferrite core 2 is not related to the time required to close or open contact springs 5 and 6. Normally the flux in the ferrite core 2 will be switched from one state to the other state before permanent magnet .9 and contact spring 6 have made more than an infinitesimal move. This fact justifies the analysis of the magnetic

core legs

18 and 19. of the current amplitude passed through

coils

13 and 22 forces between the permanent magnet and the pole faces of the ferrite core in two separate and distinct models, i.e., with permanent magnet 9 in the air gap between the pole faces of the ferrite core and with permanent magnet 9 outside of the air gap in the ferrite core.

As mentioned previously, inhibit winding 12 serves a dual function. First of all, it may be used to prevent the operation of the relay. That is, even though appropriate current signals are passed through coils 1t) and 13 the resulting magnetomotive force in ferrite core 2 can be reduced to a value insuflicient to change the state of flux in the ferrite core by means of a bucking magnetomotive force generated by the passage of current through the inhibit winding 12. This feature of the reed relay of this invention makes it particularly suitable for use in complex switching networks. The second function of inhibit winding 12 is to generate a disturbance flux in the fer-rite core 2 so that the magnetic state of the flux in the core can be ascertained. That is, the passage of a small current through the inhibit winding 12 will generate a small fluctuation in the value of the flux which can be sensed by suitable circuitry connected to sense winding 11. Through this use of the inhibit winding and the sense winding the state of the electrical contacts of the relay can be ascertained without making any electrical connection to the circuit connected through the contacts of the reed relay.

In FIG. 3 is shown a cross-sectional top view of a modification to the reed relay disclosed in FIGS. '1 and 2. All of the elements and parts of the modification shown in FIG. 3 which are denoted by a numerical time numberare identical to the corresponding par-t shown in FIG. 2. The distinctions between the reed relays shown in FIG. 3 and FIG. 2 are that the reed relay of FIG. 3 has a cross member 21 or in effect an additional magnetic path leg which can shunt the closed arc portion 20 of ferrite core 2. On this additional path leg 21 coil 22 is wound. Coil 22 corresponds to coil 10 of FIG. 2. Thus, in FIG. 3 the actuating coils for the reed relay are coils 22 and 13'. Path leg 21 is to be fabricated as an integral unit of ferrite core 2' and is composed of the same material from which ferrite core 2 is constructed.

As in the case of the reed relay of FIG. 2, the reed relay of FIG. 3 is designed to either operate or release by the simultaneous energization of both

coils

22 and 13. The magnetic flux resulting from the passage of current through coil 13' saturates the arc portion 20' of ferrite core 2, while the magnetic flux produced by passage of current through coil 22 saturates the added path leg 21 of ferrite core 2. The magnetic fluxes are oriented in the same direction in

legs

18 and 19 of ferrite core 2, thus saturating the remainder of ferrite core 2'. It is to be noted that if current is passed through only one of these two coils, the portion of the ferrite core which the other coil is wound will act as a magnetic shunt and thereby prevent, as a practical matter, the saturation of For these reasons, the regulation need not be as precise as is required in the case of the reed relay shown in FIG. 2.

FIG. 4 discloses an alternative contact arrangement for use in either the reed relays of FIG. 1 or FIG. 3. That is, contact springs 24 and 26 in FIG. 4 correspond to contact springs 5 and 6 in FIG. 1, respectively, or to contact springs 5' and 6', respectively, in FIG. 3. The distinction between this new contact arrangement and the previously considered contact arrangements is the added contact spring 25 in FIG. 4. This contact spring is inserted through the end of the glass capsule wherein contact spring 24 also is inserted. Similar to the bonding of contact spring 5 or 5', which in FIG. 4 is denoted as contact spring 24, contact spring 25 is supported and anchored at opening 33 by bonding it to the end of the glass capsule thereat. Opening 33 in the end of the glass capsule is located a sufiicient distance below opening 32 in which contact spring 24 is inserted, to insure that contact spring 26, which corresponds to contact spring 6 of FIG. 1, makes contact with it in the previously defined inoperative state of reed relay. Contact between contact springs 26 and 25 is made at contact surfaces 30 and 31 respectively. Contact surface 30 is on the bottom side of contact spring 26 opposite to contact surface 29 which makes contact with the contact surface 28 of contact spring 24 when the reed relay is operative. Contact surfaces 30 and 31 may be gold plated to reduce contact resistance. The contact arrangement shown in FIG. 4 corresponds to a single pole double throw relay switch.

FIG. 5 discloses another packaging arrangement of the relay of this invention. Here, the ferrite core 39 is completely encapsulated within the capsule. Accordingly the capsule includes in addition to portion 38 an extension 43. Therefore, the extension is that portion of the capsule which encapsulates the closed end of the core. Windings 46 and 4-7, by way of example, illustrate the manner in which the relay of this package may be threaded. A distinction between this particular package and those shown in FIGS. 1 and 3 is that the windings are wound on the extension 43 which covers the core instead of on the core directly.

FIG. 6 discloses still another packaging arrangement for the relay of the invention. Here, capsule 59 includes two or more hard glass beads 63, one of which is shown. The beads are placed into apertures 64 of the capsule 59 and bonded thereto by any means common in the art. Each bead is substantially round-shaped and preferably constructed of a very hard and ductile glass material. Each bead has one aperture 64 through which extends a contact spring, for example, contact spring 61.

The advantage of the package is that with the inclusion of the glass beads a glass to glass bond can be made with capsule 59 as compared to a glass to metal bond. Furthermore, the contact spring can be assembled into the beads before the molding of the capsule takes place. This distinction is used to greatest advantage where a hermetical seal is desired.

The four windings mentioned in connection with the relay disclosed in FIGS. 1 and 2 may also be made common to an array of relays of the invention. FIGS. 7 and 8 illustrate embodiments of such arrays. These arrays may be used with computers, registers and other electronic devices.

FIG. 7 discloses an array of 16 relays arranged in columns and rows in a single plane. Each relay in this particular array is threaded or wound, by way of example, with a vertical coordinate winding 67, a horizontal coordinate winding 68, a sense winding 71 and an inhibit winding 70. The sense winding extends through and around the cores 66 in a substantially diagonal direction to the vertical and horizontal windings and the inhibit winding extends along the rows of relays parallel to the horizontal windings.

The array is responsive upon the coincidence of currents over the horizontal and vertical windings which together sets or drives the cores into one of its two aforediscussed saturation states and actuates the corresponding contact springs 72. After the contact springs are accordingly placed in one or the other of its two possible conditions the coincident currents are removed, leaving the remanent flux to maintain that condition. To determine in which position the contact springs are in, a readout or a determination can be made by pulsing the

coincident windings

67 and 68. It is understood that the core drive pulses and the read-out pulses are sent over the same windings. If the contact springs are already switched or in a desired state no induced magnetomotive force is noticed on sense winding 71. If they are not switched, however, the read-out pulses will change the flux state of the core momentarily and thereby produce a magnetomotive force over the sense winding. As men- .tioned this change if made occurs extremely fast and $5 within the time required to change or disturb the condition of the contact springs. Therefore, read and write pulses can be sent over

windings

67 and 68 without disturbing the condition of the contacts.

The inhibit winding 70 threads each relay of the array and functions primarily as a control winding. By applying a voltage to this winding one of the coordinate windings, that is either the vertical winding 67 or horizontal winding 68, is opposed and a result the setting up of the core is blocked. Since the inhibit winding would block an entire array in a single plane it is preferably used in situations where a number of arrays such as shown in FIGS. 7 or 8 are stacked one above the other, or a multiplane arrangement. The inhibit winding then would block the actuation of the contacts in certain planes. For example, in a 5 plane system, the inhibit winding may be used to block or oppose saturation of cores in planes 2 and 5 and allow the remaining planes, or more particularly the relays contained therein, to operate.

FIG. 8 discloses the second embodiment for an array of relays of the invention. This particular arrangement is referred to in the art as a word-oriented arrangement. Here, the sense winding 74 threads each relay and extends vertically parallel to a Y-digit winding 75. Winding 76 represents the reed winding of the array and winding 77 represents a X-write winding of the array.

The coincidence of currents over

windings

75 and 77 are required to set up the core just as in the array of FIG. 7. In this array, however, the current over the read-winding 76 is of an amplitude equivalent to the combined amplitudes of the coincident currents over winding 75 and 77. Thus, in comparison to the array of FIG. 7 to drive the cores into saturation it is necessary to apply coincident currents but to read the state of the core the coincidence of currents is not required.

It is to be emphasized that in both arrays shown the time interval required to read and write is within the time interval required to change the condition of the contacts and thus the read-out can be made to determine the condition of the contact springs without disturbing them.

When using relays of the type depicted in FIG. 3 in an array such as shown in FIGS. 7 and 8 the read and write pulsing would not necessarily have been done within the time interval aforementioned for the contact springs to change. This is providing that the coincident current drive windings, such as 67 and 68, and if desired an inhibit windings such as 70, are placed on the cross member 21 and a X-read winding (not shown) and a Y-read winding (not shown) together with a sense winding are placed on the closed portion of the core. These windings would respond in a manner such that the flux through the cross member 21 is sufficient to maintain the condition of the contact springs even though current pulses over the X and Y-read windings are being sent. Therefore, a read-out could be made without changing the magnetic state of the core, or in other words, the core would function as a non-destructive type.

While what has been described above are the principles of the invention in connection with specific embodiments, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of this invention.

What is claimed is:

1. An electromagnetic relay comprising:

encapsulating means forming a sealed chamber; a core structure of square loop hysteresis material, said core structure being in the shape of an elongated U with two leg portions and a bite portion, having pole faces located at the ends of said leg portions to define an air gap, being rigidly connected to said encapsulating means and extending lengthwise thereto with said pole faces located within said chamber and said bite portion outside of said chamber; winding means posi- 9: tioned on said bite portion, said winding means, upon energization, switching said core from one remanent magnetic state to the other, thereby reversing the direction of the magnetic field across said air gap;

a pair of reeds secured to the opposite ends of, and having their free ends and a corresponding pair of cooperating contact portions movable within said chamber; a permanent magnet mounted on one of said reeds near said free end thereof and aligned with said air gap, said permanent magnet being attracted towards or repelled from the plane of said air gap by said field, said one reed thereby being carried along by said magnet, causing engagement or disengagement of said contact portions depending on the polarity of energization of said winding means.

2. An electromagnetic relay as claimed in claim 1, wherein said core structure has furthermore a cross member extending intermediate said two leg portions and located adjacent to but spaced from said bite portion outside of said chamber, the cross-sectional area of said cross member being less than the cross-sectional area of each of said leg portions, and wherein said winding means includes a plurality of windings, at least one of said windings being wound around said cross member, said cross member aiding or shunting the saturation of said leg portions depending on the polarity of ener-gization of said winding wound around said cross member.

3. An electromagnetic relay as claimed in claim 1 wherein said encapsulating means has two holes in the opposite ends thereof with a pair of glass beads received by said holes, and each of said beads having an aperture therethrough and each of said reeds extending through one of said apertures so that said free ends of said corresponding pair of cooperating contact portions are located movably within said chamber.

4. An electromagnetic relay comprising: an elongated vitreous tube forming a sealed chamber, an armature contact spring supported by and extending through one end of said vitreous tube and having its free end movable within said chamber, a pair of substantially fixed contact springs arranged and constructed to cooperate with said free end of said armature spring and extending through the other end of said vitreous tube, one of said fixed contact springs being positioned relative to said armature spring to serve as a make contact spring and the other being positioned relative to said armature spring to serve as a break contact spring, a ferrite core structure having a bite portion and two leg portions with pole faces located at the ends thereof to define an air gap, said core structure extending from the same end of the vitreous tube as said armature spring and lying in a plane parallel therewith, the bite portion of said core structure extending externally of said chamber and said leg portions extending internally of said chamber, winding means positioned on said bite portion, said winding means, upon energization, switching said ferrite core structure from one remanent magnetic state to the other, thereby reversing the direction of the magnetic field across said air gap, a permanent magnet element mounted near said free end of said armature spring and being aligned with said air gap, said permanent magnet element being attracted towards, or repelled from the plane of said air gap by said magnetic field, said armature spring being carried along by said magnet, disengaging from said break spring and engaging with said make spring.

5. An electromagnetic relay comprising: an elongated vitreous tube including a sealed chamber, a pair of reed members each having two ends and contact portions, said reed members being secured at and extending through opposite ends of said chamber, said contact portions being engageable with respect to each other within said chamber, a ferrite core structure being in the shape of an elongated U with two leg portions and a bite portion and having pole faces located at the ends of said leg portions to define an air gap, said core structure being encapsulated within said vitreous tube and extending parallel to one of said reed members, said pole faces located within said chamber and said bite portion located outside of said chamber, winding means positioned on said vitreous tube in such a manner that upon energization of said winding means, said core structure switches from one remanent magnet state to another, thereby reversing the direction of said magnetic field across said air gap, a permanent magnet mounted on said one reed member near said free end thereof and aligned with said air gap, said permanent magnet being attracted towards or repelled from the plane of said air gap by said field, said one reed thereby being carried along by said magnet, causing engagement or disengagement from said contact portions depending upon the polarity of energization of said winding means.

References Cited by the Examiner UNITED STATES PATENTS 2,170,694 8/39 Perry 340-174 X 2,360,941 10/44 Eitel 200-87 2,397,116 3/46 Armstrong 340174 X 2,907,846 10/59 Wilhelm 200-93.4 2,970,296 1/61 Horton M 340174 3,002,067 9/61 Baldwin 200--93.4 3,007,141 10/61 Rising et al 340-174 3,008,020 11/61 Mason 20093 3,008,021 11/61 Pollard 20093.4

IRVING L. SRAGOW, Primary Examiner.

Claims

1. AN ELECTROMAGNETIC RELAY COMPRISING: ENCAPSULATING MEANS FORMING A SEALED CHAMBER; A CORE STRUCTURE OF SQUARE LOOP HYSTERESIS MATERIAL, SAID CORE STRUCTURE BEING IN THE SHAPE OF AN ELONGATED U WITH TWO LEG PORTIONS AND A BITE PORTION, HAVING POLE FACES LOCATED AT THE ENDS OF SAID LEG PORTIONS TO DEFINE AN AIR GAP, BEING RIGIDLY CONNECTED TO SAID ENCAPSULATING MEANS AND EXTENDING LENGTHWISE THERETO WITH SAID POLE FACES LOCATED WITHIN SAID CHAMBER AND SAID BITE PORTION OUTSIDE OF SAID CHAMBER; WINDING MEANS POSITIONED ON SAID BITE PORTION, SAID WINDING MEANS, UPON ENERGIZATION, SWITCHING SAID CORE FROM ONE REMANENT MAGNETIC STATE TO THE OTHER, THEREBY REVERSING THE DIRECTION OF THE MAGNETIC FIELD ACROSS SAID AIR GAP; A PAIR OF REEDS SECURED TO THE OPPOSITE ENDS OF, AND HAVING THEIR FREE ENDS AND A CORRESPONDING PAIR OF COOPERATING CONTACT PORTIONS MOVABLE WITHIN SAID CHAMBER; A PERMANENT MAGNET MOUNTED ON ONE OF SAID REEDS NEAR SAID FREE END THEREOF AND ALIGNED WITH SAID AIR GAP, SAID PERMANENT MAGNET BEING ATTRACTED TOWARDS OR REPELLED FROM THE PLANE OF SAID AIR GAP OF SAID FIELD, SAID ONE REED THEREBY BEING CARRIED ALONG BY SAID MAGNET, CAUSING ENGAGEMENT OR DISENGAGEMENT BY SAID CONTACT PORTIONS DEPENDING ON THE POLARITY OF ENERGIZATION OF SAID WINDING MEANS.