US3510812A - Polarized reed relay - Google Patents

Description

*My 5, 1970 MASAO'TAKAMURA ETAL I 3,510,812

POLARIZED REED RELAY Filed April 19, 1968 7,111,111.11. "11111 lll F. E i INVENTORS d Mosao Tokamuro Ig f Koisuhro Kom l Tokeo Shnohurcl Hsuhide Kikuchi Sodoyuk Mifsuhosh ATTORNEYS United States Patent O U.S. Cl. 335-153 10 Claims ABSTRACT OF THE DISCLOSURE Polarized reed relay apparatus is provided which is highly stable and in operation requires only relatively low current magnitudes to change the state thereof. In one embodiment, the state of the reed switch is determined by the magnetic condition of remanent material disposed in a parallel relationship therewith. The unitary remanent material is magnetically separated into two portions wherein a first portion may be magnetically driven to a first or second state and the second portion thereof in maintained in a first magnetically polarized state. The reed switch will be maintained in the closed condition when said first portion is magnetized in the same direction as said second portion and the open position will be established when said first portion is magnetized in another direction.

This invention relates to magnetic switch or relay apparatus and, more particularly, to polarized reed relay apparatus of the latching type having a series magnetic circuit.

Although this invention is not limited to use with any particular apparatus or in conjunction with any specified combination, the polarized reed relay apparatus according to the present invention admits of wide use within telephone switching systems and electronic equipment in general, and has particular application as a channel cutoff relay in electronic switching systems.

Present day polarized reed relay apparatus normally comprises a reed switch, a magnetic shunt plate for mag netically separating the reed switch into two portions in the longitudinal direction, a permanent magnet means disposed on one of said two portions, a semihard magnet material disposed on the other of said two portions, and coil means wound about said semihard magnetic material. The operation of these devices has, however, suffered because the magnetic coupling therein is inherently loose due to the presence and location of the shunt plate utilized therein. In addition, when the semihard magnetic material present in such devices is magnetized in the sarne direction as the permanent magnet means, a demagnetizing field is present in the vicinity of the end portions of these polarized elements which face each other over said magnetic shunt plate. This demagnetizing field thereby causes a weakening of the magnetic field in the area of the shunt plate which manifests itself in a corresponding reduction of the field intensity at the contact portions of the reed switch. Thus, to insure the proper operation of the polarized reed relay apparatus of the prior art, coil means having large ampere-turn products were necessary and such large ampere-turn products were normally achieved by using relatively high current magnitudes with their inherent expense and disadvantges.

Therefore, it is a primary object of this invention to provide polarized, latching reed relay apparatus which is operable with relatively low current magnitudes, is highly stable in operation, and is not subject to faulty operation due to the non-uniform magnetization of its respective ice remanent members. Various other objects and advantages of the invention will become clear from the following detailed description of the embodiments disclosed herein, and the novel features of the present invention will be particularly pointed out in connection with the appended claims.

In accordance with the invention, polarized, latching reed relay apparatus is provided wherein a reed switch is operated by the magnetizing force applied by a semihard magnetic material disposed in a parallel relationship with said reed switch; the semihard magnetic material being adapted for magnetic separation into first and second portions whereby said second portion thereof is polarized by a magnetically hard material in a first direction while the first portion thereof is acted upon by a field applying means which is capable of magnetizing said first portion in either a first or second direction. The invention will be more clearly understood by reference to the following detailed description of several embodiments thereof in conjunction with the accompanying drawings in which:

FIGS. 1(a)l(b) show a first embodiment of the polarized reed relay apparatus according to this invention wherein FIG. 1(11) is a detailed structural view, partially in section, of said first embodiment, and FIG. 1(b)-l (d) illustrate various coercive force distributions along the longitudinal axis of the FIG. l(a) structure; and

FIG. 2 is a detailed structural view, partially in section, of a second embodiment of the polarized reed relay apparatus according to this invention.

Referring now to the drawings and more particularly to FIG. l thereof, there is shown a first embodiment of the polarized reed relay apparatus according to the present invention. The apparatus depicted in FIG. 1(a) comprises a reed switch 1, magnetic members 2 and 2', a magnetic shunt plate 3, magnetomotive force applying means 4-4; and permanent magnet means 5 and 5. The depicted reed switch 1 may take the well known form wherein two overlapping, thin magnetic reeds 1 are encapsulated within a sealed glass chamber. Magnetic members 2 and 2 which may take the form of two fiat bars of magnetic material, are mounted in a parallel relationship with the thin magnetic reeds 1 on the outside of the glass chamber. The magnetic members 2 and 2 are preferably formed of a semihard magnetic material whose domains are capable of remaining in a stable, aligned remanent condition once they have been subjected to an external magnetic field, but which domains are sufficiently mobile so that their orientation may be reversed to a second stable, aligned condition by an oppositely directed external field applied subsequently. The magnetic members 2 and 2 have located at their approxiate centers, a magnetic shunt plate which is made of soft magnetic material. The magnetic shunt plate 3 is positioned so that the magnetic members 2 and 2 may be magnetically separated, on either Side of the central axis of said shunt plate 3, into two adjacent magnetic portions. The two adjacent portions thereby formed are each located opposite one of the two thin magnetic reeds 1' which reeds in turn overlap in the area of the magnetic shunt plate 3. A first magnetic portion of each of the magnetic members 2 and 2', as herein shown to the right of the magnetic shunt plate 3, is wound by a magnetomotive force applying means 4 4' which may be an ordinary exciting coil, as indicated by the cross-sectional showing thereof which is annotated 4-4. The magnetomotive force applying means 4-4 is connected in the usual manner to a standard current driver, not shown herein, so that current pulses may be applied thereto and thus positive or negative current caused to flow therein in either a first or second direction to thereby establish a first or second axial field. Such first or second fields will respectively be directed toward or away from said magnetic shunt plate 3. The coercive force distribution along each of said magnetic members 2 and 2', as applied solely by the magnetomotive force applying means 4-4', when energized, is shown in FIG. l(b). The effect of magnetic shunt plate 3 is also clearly demonstrated in FIG. 1(1)) wherein the rapid dropoff in the magnitude of the coercive force on the opposite side of the magnetic plate 3 is clearly indicated by the shaded portion thereof.

A second magnetic poriton of each of the magnetic members 2 and 2', as herein shown to the left of the magnetic shunt plate 3, has its domains unidirectionally aligned by the magnetic and mechanical coupling thereto of permanent magnet means and 5 respectively. The permanent magnet means 5 and 5' each preferably exhibit a large amount of residual magnetism and hence manifest a coercive force which is substantially larger than that of the magnetic members 2 and 2. This coercive force should be sufficiently large so that neither the permanent magnet means 5 or 5' or the second magnetic portions of the magnetic members 2 or 2', which are respectively coupled thereto, will be demagnetized by the leakage flux produced by the exciter coil 4-4' as indicated by the shaded portion of FIG. l(b). In practice, when close coupling is achieved between the permanent magnet means 5 and 5' and the magnetic members 2 and 2', the values of the coercive force and the demagnetizing factor in the permanent magnet means 5 and 5 should be about three times greater than that of the magnetic members 2 and 2'.

In operation, the apparatus shown in the FIG. l embodiment is a basic bistable switching device which may be set in either the opened or closed switch position and thereafter retain this position unless the condition thereof is subsequently altered. The reed switch 1 operates in the well known manner such that the thin magnetic reeds 1' therein will be drawn together in response to flux present between their overlapping portions and will separate in the absence of flux between said overlapping portions. Thus an open or closed reed switch condition is achieved. The presence or obsence of flux in the overlapping portions thereof as will be seen hereinafter, is determined by the magnetic condition of the magnetic members 2 and 2' and more particularly the relative magnetic conditions of the respective first and second mangetic portions thereof.

The second magnetic portion of each of the magnetic members 2 and 2', as shown herein to the left of the magnetic shunt plate 3, is mechanically and magnetically coupled, as aforesaid, by the permanent magnet means 5 and 5' respectively, and is thus closely coupled thereto.

The continuous application of the coercive force manifested by the permanent magnet means 5 and 5' to the respective second magnetic portions of each of the magnetic members 2 and 2' causes the magnetic domains therein to be aligned in the direction of the constant magnetic field applied thereto. This direction of orientation is indicated by the arrows shown in the left hand portion of FIGS. 1\(a)1 (d). The second magnetic portions of each of the magnetic members 2 and 2' are, therefore, uniformly magnetized in the direction of the illustrated left-hand arrows and thus act to polarize the left hand portion of the reed switch 1 in the direction of the magnetic field applied thereby. This continuously applied field is indicated by the second quadrant portions of the coercive force distribution curves depicted in FIGS. 1(c) and l(d).

The first magnetic portions of each of the magnetic members 2 and 2', as shown herein to the right of the magnetic shunt plate 3, are wound, as aforesaid, by a magnetomotive force applying means which is depicted as an ordinary exciting coil 4-4'. The standard current driver, not shown herein, which is connected in the usual :manner thereto, may be energized by the actuation of ordinary switching apparatus normally utilized therewith so as to apply current pulses of either a rst or second polarity, or in a first or second direction to the exciting coil 4-4'. The application of current pulses to the exciting coil 4e4 of a first or second polarity or in a first or second direction establishes, in the well known manner, first or second axial fields respectively in the space linked by said exciting coil 4-4'. The direction of such first or second axial fields is indicated by the right-hand arrows shown in FIGS. 1(0) and 1(d), respectively. The first magnetic portions of the magnetic members 2 and 2', are wound by said exciting coil 4-4 and thus the magnetic domains therein will tend to align with the axial fields produced thereby. Once the magnetic domains in said first portions have aligned with the applied magnetic field, the current driver may be de-energized as said first portions will retain, in the well known manner, the remanent -magnetic state to which it was switched. The first magnetic portions of each of the magnetic members 2 and 2' may be thus uniformly magnetized in either of said aforesaid first or second directions and may therefore act to polarize the right-hand portion of the reed switch 1 in the direction of the magnetic field applied thereby. These fields are indicated by the portions of the coercive force distribution curves depicted in the first quadrant of FIG. 1(d) and the fourth quadrant of FIG. l(c).

The magnetic field generated by the exciting coil 4-4' will have little or no effect on the second magnetic portions of each of the magnetic members 2 and 2' :because the magnetically soft shunt plate 3 will shield said second portions therefrom and any leakage fiux which may be applied thereto, as illustrated by the shaded portion of FIG. l(b), will be of insufficient magnitude for the reasons stated above, to change the remanent state of said second portions. Thus, it is seen that although the second manetic portions of each of the magnetic members 2 and 2' are maintained by the permanent magnet means S and 5' in a first magnetic state, the first magnetic portions of each of the magnetic members 2 and 2 may be remanently magnetized by the selective energization of the exciting coil 4-4' in either a first state which is the same as that of said second portions or a second state, opposite to that of said second portions.

When current pulses are applied to the exciting coil 4-4 so that the first magnetic portions of each of the magnetic members 2 and 2 are remanently magnetized in the first direction, both of said first and second magnetic portions of said magnetic members 2 andy 2 will be magnetized in the first direction. This creates at least a remanent condition in said first magnetic portions so that when the field applied by the exciting coil 4-4 is turned off, the desired magnetic state will =be maintained. Since the magnetic domains in each of said first and second magnetic portions of said magnetic members 2 and 2' all tend to align in the same direction, the magnetic domains at the Iboundary between said first and second portions, under the magnetic shunt plate 3, will also tend to align in this direction due to normal domain propagation. Thus the magnetic members 2 and 2' will tend to manifest the open fiux path lof a single piece of aligned magnetic material. Accordingly, both of the magnetic reeds 1 of the reed switch 1 are linked by a unidirection flux field which will cause the magnetic reeds 1 therein to close at the overlapping portions thereof and to be maintained in this closed condition until the coercive force applied thereto is modified by a change in the state of the first portion of said magnetic members 2-2'. The coercive force distribution along the magnetic reeds 1' when both of said first and second magnetic portions of said magnetic members 2 and 2 are magnetized in the same condition is illustrated in FIG. 1(d). As can be seen by the inspection thereof, a stable, uniform magnetizing force is applied to reed switch 1 to maintain it in its closed condition.

If current is thereafter applied to the exciting coil 4,-4 S0 as to apply a magnetomotive force to the first mag.-

netic portions of the magnetic members 2 and 2' in the opposite direction to thereby change their remanents state to the second state described above, said iirst portions will be remanently magnetized in an opposite direction to that of the second portions of said magnetic members 2 and 2'. The first and second portions of said magnetic members 2 and 2' will thereby exhibit oppositely directed open iiux paths and the sections of the magnetic members 2 and 2' underlying said magnetic shunt plate 3 will tend toward a magnetically neutral state which serves as a buffer between the oppositely magnetized first and second portions. The right and left magnetic reeds of the reed switch 1 will thereby be linked by oppositely directed flux and the overlying conL tact portions thereof will either not be linked fby the separate and oppositely directed flux paths or if any fringing ux from one of said magnetic portions happens to link said contact portions, it will be cancelled by fringing flux from the other of said magnetic portions. Thus, the overlapping contact portions of the magnetic reeds 1' are linked by zero effective flux and the reed switch 1 is maintained in an open condition. The coercive force distribution along the magnetic reeds 1 when each of said first and second magnetic portions of said magnetic members 2 and 2 are oppositely magnetized is illustrated in FIG. 1(0). As can be seen by inspection thereof, a zero magnetizing force is present in the area of the contact portions of the magnetic reeds 1 so that said reed switch 1 is readily maintained in the open condition. If it is thereafter desired to close the reed switch 1, it is merely necessary to energize the eX- citing coil 4-4 with current pulses tending to drive said first magnetic portions of said magnetic members 2 and 2 toward said first remanent state.

'Ihus it is seen that the apparatus described in the FIG. l embodiment of the instant invention provides polarized latching relay apparatus that is highly stable in each of its operating conditions and not subject to faults due to the nonuniform magnetization of its respective magnetic members.

The apparatus as shown in the FIG. 2 embodiment of the present invention illustrates multiple contact reed relay apparatus in accordance with the teachings of the invention. The depicted apparatus comprises rst and second reed switches and 10', magnetic member 12, a magnetic shunt plate 13, magnetomotive force applying means 14, and permanent magnet means 15. The reed switches 10 and 10 may again take the well known form described in conjunction with FIG. l(a) wherein two overlapping, thin magnetic reeds 11 and 11 are encapsulated within a sealed glass chamber. The magnetic member 12, which may take the same form and substance as described with regard to FIG. 1(a), except that it is double the thickness of the single members disclosed therein, as shown, is mounted in a parallel relationship with the th-in magnetic reed pairs 11 and .11 intermediate said reed switches 10 and 10'.

The magnetic member 12 has located at its approximate center, a magnetic shunt plate 13 which is again made of soft magnetic material and serves to magnetically separate the two portions of the magnetic member 12 on either side thereof. In addition, the magnetic shunt plate 13 is extended to the opposite -sides of the reed switches 10 and 10 to isolate the contact portions thereof from spurious fields which may be created by the magnetomotive force applying means 14. A first magnetic portion of the magnetic member 12 is wound by the magnetomotive force applying means 14 which again may take the form of an ordinary exciting coil. The magnetomotive force applying means 14 is also connected, in the usual manner, to a standard current driver, not shown herein, which is capable of performing the same functions as was that described with regard to FIG. 1(a). The second magnetic portion of the magnetic member 12 has its domains unidirectionally aligned 6 by the permanent magnet means 15 mechanically and magnetically coupled thereto. The permanent magnet means 15 may take the same form and have the same characteristics as that described with regard to FIG. 1(a).

In operation,l the multiple contact reed relay apparatus as shown in FIG. 2 has precisely the same mode and theory of operation as that described with regard to FIG. l. Here, however, the multidirectional characteristc of the magnetic iiux path is taken advantage of to provide for the operation of a plurality of reed switches 10 and 10 in unison. Thus, when the first and second magnetic portions of the magnetic member 12 are aligned in the same direction, both of the reed switches 10 and 10' will be in the closed condition and will remain in this stable, closed condition until such time as the magnetic state of the rst magnetic portion of the magnetic member 12 is reversed whereby said reed switches will be opened. As will be obvious, additional reed switches may be incorporated into embodiments similar to that shown in FIG. 2 so long as the thickness of the magnetic member 12 is continuously increased to provide additional magnetomotive force thereto.

Thus, the apparatus disclosed in the FIG. 2 embodiment of the present invention provides polarized multiple contact reed relay apparatus of the latching variety which is highly stable in operation and free from magnetic operating deficiencies.

Although the described embodiments of the present invention have relied upon the utilization of a magnetic shunt plate to shield and isolate the second magnetic portion of the magnetic member from rst magnetic portion of said member, it has been found that said magnetic shunt plate Iis unnecessary if the magnetic coupling between the permanent magnet means and the magnetic member is close and the ratio of their respective coercive forces exceeds five. Furthermore, a substantial increase in the length of the magnetic member with the retention of similar exciting windings and permanent magnet means would seem to accomplish the same result. In addition, although the permanent magnet means have been shown in the disclosed embodiments as coextensive in areas with the second portion of the magnetic member, such coincidence in area is not necessary as the illustrated embodiments will operate satisfactorily if only 10% of the permanent magnet means is overlapped by the second portion of magnetic member.

It will be noticed that the magnetic coupling between said first and second portions of said magnetic members approaches the ideal case because the entire coupling therebetween takes place through an integral piece of magnetic material. Thus, low switching current pulses may be applied to the exciting coil with their advantageous mode of operation and their inherent economy. Further, when both magnetic portions of the magnetic members are magnetized in the same direction, the magnetic separateness of said rst and second portions is destroyed thereby causing the magnetic members to exhibit a uniform, a stable magnetic condition.

It will thus be seen that the instant invention provides polarized, latching reed relay apparatus, operable at relatively low current magnitudes, which is highly stable in both of its switch positions and not subject to faults due to non-uniform magnetization of its respective remanent members.

While the invention has been described in connection with two specific embodiments thereof, it will be understood that many modifications will be readily apparent to one of ordinary skill in the art; and that this application is intended to cover any adaptations or variations thereof. Therefore, it is manifestly intended that this invention be only limited by the claims and the equivalents thereof.

We claim:

1. Polarized reed relay apparatus comprising:

reed switch means having at least first and second thin reed means mounted therein, said thin reed means having portions thereof adapted for contact theref between; i i

'.mag'netic member .means disposed in a parallel relationship with saidreed switch means, said magnetic member means exhibiting magnetic hysteresis and the incident remanent magnetic properties thereof;

`means. magnetically dividing said reed switch means at the contact portions of said thin reedmeans, said magneticidividing means further acting to magnetically divide a first portionlof said magnetic member means from a second-portion thereof;

first magnetomotive field applying means mounted in an operative relationship with said first portion of said magnetic member means, said first magnetomotive field applying means adapted when energized to selectively drive said first portion of said magnetic member means toward a first or second-magnetic state; and

second magnetomotive field applying means magnetically coupled to said second portion of said magnetic member means, said second magnetomotive field applying means comprising permanent magnet means adapted to maintain said second portion of said magnetic member means in a first magnetic state, whereby said reed switch means will be in a closed switch condition when said first and second portions of said magnetic member means are each in said rst magnetic state and said reed switch means will be in an open switch condition when said first and second portion of said magnetic member means are each in different magnetic states.

2. The apparatus of claim 1 wherein said second magnetomotive field applying means is mechanically coupled to said second portion of said magnetic member means.

3. The apparatus of claim 2 wherein said first magnetomotive eld applying means comprises coil means wound about said rst portion of said magnetic member means.

4. The apparatus 'of claim 3 wherein said means magnetically dividing said reed switch means comprises magnetic shunt plate means made of magnetically soft material.

5. The apparatus of claim 4 wherein said magnetic member means comprises at least a first and second discrete magnetic member, said first and second discrete magnetic members being disposed on either side of said reed switch means.

p 6. The apparatus'of claim 5 wherein said coil means is wound about said .first portion of eachofsaid first and second discrete magnetic members and in addition thereto is wound about a portion of said reed switch means.

7. The apparatus of claim 6 wherein said permanent magnet means constitutes at least first and second permanent magnet means fixedly mounted respectively to said second portion of each of said first and second discrete magnetic members.

8. The apparatus of claim 4 wherein said reed switch means having at least first and second thin reed means mounted therein includes at least first and second separate reed switches.

9. The apparatus of claim 8 wherein said magnetic member means comprises a single bar of magnetic material interposed between said first and second separate reed switches.

10. The apparatus of claim 9 wherein said coil means is Wound solely about'said first portion'of said magnetic member and said permanent magnet means is fixedly mounted to said second portion of said magnetic member.

References Cited UNITED STATES PATENTS 2,877,315V 3/1959 Oliver a 335-153 3,075,059 1/1963 Bla'ha et al. 335--153 3,382,468 5/1968 Mattes 335-153 BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, IR., Assistant Examiner

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