United States Patent 3869684

A bistable latching relay comprising a pair of reversible permanent magnet cores extending through and attached to a soft magnetic baseplate by means of glass-to-metal seals. A soft magnetic reed contact is attached to one end of each core so that the reed contacts overlap and provide an electrical contact gap for the relay. The relay is hermetically sealed within a cover to provide a dust-free enclosure for the contacts. The magnetism of each core is transmitted to the soft magnetic reed contacts attached to the ends of the cores to provide magnetic latching. Electromagnetic coils surrounding each core determine the magnetic sense of the core when energized and, depending upon the direction of the current through the coil, cause the reed contacts to open or to close. The current pulse in one direction, for example, momentarily causes the contacts to close, wherein the bistable latching property is accomplished by the transmission of the remanent magnetism of the coil to the reed contacts.

Application Number:
Publication Date:
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Primary Class:
Other Classes:
International Classes:
H01H51/28; (IPC1-7): H01H1/66
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US Patent References:
3363203Bistable operating reed relay1968-01-09Schadewald
3321723Sealed switch assembly with improved connecting means1967-05-23Chanowitz
3275960Bistable magnetically controlled switch1966-09-27Gartner et al.

Primary Examiner:
Harris G.
Attorney, Agent or Firm:
O'halloran Jr., John Lombardi Menotti Menelly Richard T. J. A.
1. A bistable latching relay comprising:

2. The bistable latching relay of claim 1 wherein said soft-magnetic reed

3. The relay of claim 1 further including an auxiliary restoring spring

4. The relay of claim 1 wherein said reed contacts and said electrical terminal connection members are fixedly attached to said magnetic cores.

5. The relay of claim 1 wherein said reed contacts are connected to said

6. The relay of claim 1 wherein said reed contacts comprise spiral-shaped members surroundingly attached at one end to said magnetic cores whereby said opposite ends overlappingly oppose corresponding opposite ends of

7. The relay of claim 1 further comprising a plurality of pairs of magnetic

8. The relay of claim 1 wherein an electromagnetic coil surrounds more than

9. The relay of claim 1 wherein a series of said relays are arranged so that the cores of each said relay opposingly faces the cores of another said relay in the series and the coil of one said relay surroundingly

10. The relay of claim 1 further including a cover hermetically sealed to said base plate for providing a dust-free enclosure to the reed contacts contained therein.


The present invention relates to a bistable magnetic latching relay with hermetically sealed or protected reed contacts and permanent magnets capable of being subjected to polarity reversals by at least one coil respectively, operating on the series-ferreed principle.

The ferreed principle is described in German Pat. No. 1,154,870 and in two articles published in "The Bell System Technical Journal," of Jan. 1960 and Jan. 1964, respectively. The name "ferreed" is composed of the abbreviations for the words ferrite and reed contact, which basically consists of a suitable combination of reversible permanent magnets with reed contacts. Conventional types of ferreeds are all provided with reeds hermetically sealed into small glass tubes (envelopes).

Moreover, self-latching reed contacts contain reeds which are made from a reversible hard-magnetic material. In one conventional type of magnetic latching relay the had-magnetic reeds are given the necessary spring properties by way of flat stamping. Magnetically hard materials, however, are mostly also mechanically hard; and flat stamping of this material is very difficult because of the high tool requirements. In another conventional hard-magnetic reed, each of the contacts contain short flat springs which are secured to a rod-shaped part sealed into the (protective) contact tube by way of spot welding. This type of construction, however, is complicated and expensive, because four welding points have to be arranged inside the protective contact tube which are not very structurally reliable.


This invention, therefore, comprises reversible remanent-magnetic cores secured in pairs by means of glass-to-metal sealing in a baseplate. The cores transmit their magnetic flux through the baseplate, to soft-magnetic armature contacts cooperating in pairs. Electromagnetic coils supply magnetic energy to these cores to open and close the soft armature contacts. The relays are bistable since the permanent magnetic flux through the cores transmits to the contacts and allows them to remain magnetically coupled when the energizing magnetic field is turned off. Reversing the polarity of the energizing fields causes the contacts to open.

German Printed Application (DAS) 1,194,980 discloses an electromagnetic relay for polarized operation in which a permanent magnet is secured in a baseplate by means of glass-to-metal sealing. This permanent magnet, however, is not reversible and the aforementioned relay therefore does not operate on the ferreed principle.

With the bistable latching relay of the instant invention it is possible to avoid the disadvantages of latching crosspoint elements employing self-latching reed contacts. Production thereof becomes simple because the relatively hard reversible permanent magnetic parts of the magnet circuit do not need to be stamped. The use of glass-to-metal sealing makes it possible to attach electromagnetic coils with a small number of turns.


FIG. 1 shows an electromagnetic switching device forming part of a crosspoint switching matrix array, on an enlarged scale and in a sectional side view;

FIG. 2 shows the reed contacts as secured to the cores, in a plan view; and

FIG. 3 shows the part of the crosspoint array according to FIG. 1, in a schematic three-dimensional representation.


FIG. 1 shows two oppositely arranged baseplates 1, 2 in each of which two reversible, remanent-magnetic cores 3 and 4 or 5 and 6 are secured by means of the glass-to-metal sealing method, respectively. The cores 3, 4, 5 and 6 of the baseplates 1, 2 are inserted each in common excitation coils 8, 9 or 10, 11 respectively, i.e. the cores 3 and 5 are surrounded by the two coaxial exciting coils 8, 9. The cores 3 and 5 or 4 and 6 are electrically separated from one another by means of insulations 20, and forward their magnetic flux at their ends 12, 13, 14, 15 extending through the baseplates 1, 2 to soft-magnetic reed contacts 16, 17, 18, 19 cooperating in pairs. The reed contacts 16, 17, 18, 19 are designed to act simultaneously as reset (restoring) springs, and are form-lockingly and intimately connected to the cores 3, 4, 5, 6. The electrical terminals of the contacts are formed by tapes 21, 22, 23, 24 which are secured to the cores 3, 4, 5, 6 in the same way. The baseplates 1, 2 each carry over the reed contacts 16, 17, 18 or 19 a protective capsule 25 or 26 respectively. Owing to the soft-magnetic baseplates 1, 2 the pairs of reed contacts 16, 17 and 18, 19 are prevented from mutually affecting one another. The magnetic circuit is comparatively well completed. The shape of the reed contacts 16, 17 is clearly recognizable from the plan view shown in FIG. 2. These contacts are of spiral-shaped design and form-lockingly surround the ends 12 or 13 of the cores 3 or 4 respectively. The form-locking connections are sealed at the edges of the reed contacts 16, 17 additionally with the aid of either electron beams or laser beams. The free contact-making ends 27 and 28 of the reed contacts 16 and 17 oppose one another overlappingly. Auxiliary contact restoring springs 16a as described in the aforementioned prior art can be attached between contacts 16 and rod-shaped parts 16b sealed into the contact by means of spot welding.

As regards the use in crosspoint arrays of telephone switching systems, there is especially to be noted the assembly of crosspoints extending via coordinates. A row-wise integration is possible because the switching device is built up in such a way that the protective capsule 25, 26 has no other functions besides providing the hermetic seal and the mechanical protection. Accordingly, the crosspoint or the row of crosspoint elements is completely accessible in its full functionable state. When using suitable contact materials it is sufficient to provide a dust-proof enclosure, and the protective capsule 25, 26 may be of the detachable type. In this way maintenance works on crosspoint arrays can be carried out in a sensible way.

In manufacturing the described latching relay the contact materials, prior to the singling out of the reed contacts 16, 17, 18, 19 are attached to tapes. Instead of the well-known spot weldings, the reed contacts 16, 17, 18, 19 are secured to the permanent magnetic cores 3, 4, 5, 6 by way of reliable edge weldings. Subsequently thereto, the cores 3, 4, 5, 6 are inserted into the baseplates 1, 2 by providing glass-to-metal seals 7. In so doing, they already carry the reed contacts 16, 17, 18, 19. The magnetic and, at the same time, the electrical operating airgap 29 is adhered to by the shape of the receiving device during the sealing process. The sealing times are very short, because heating is carried out in batches. Prior to the positioning of the protective capsule 25, 26 it is possible to readjust the reed contacts 16, 17, 18, 19.

While the principles of this invention have been described above in connection with specific apparatus, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention as set forth in the objects and features thereof and in the accompanying claims.