US3408603A - Shielding arrangement for a reed relay - Google Patents

Description

Oct. 29, 1968 R. MORRISON SHIELDING ARRANGEMENT FOR A REED RELAY 2 Sheets-Sheet 1 Filed July 1, 1966 irrazaexr United States PatentOflice The present invention relates to an improved reed relay carried by' the current paths and wherein capacitive coupling across netizes the reeds, so they come together into electrical contact. Both single-throw and double-throw relays have been used in the past.

' In general, reed relays have been controlled current paths.

Another object of the present invention is to provide an improved electro-magnetic reed relay structure which may be inexpensively manufactured.

Still another object-of is employed, which material is eco- 3,408,601 Patented Oct. 29, 196i One other object of the present invention is to provide an improved relay structure in which nal coupling between open contacts is reduced.

These and other objects and advantages of the present invention will become apparent from a consideration of the following, taken' in conjunction with the drawings, wherein:

' FIGURE 1 is a perspective view of a reed relay constructed in accordance with the principles of the present invention;

FIGURE 2 is a fragmentary vertical sectional view taken along the central axis of the cylindrical structure of FIGURE 1;

FIGURE 3 is a sectional view taken through the structure of FIGURE 1;

FIGURE 4 is a diagrammatic representation of an illustrative structure incorporating the principles of the present invention;

FIGURE 5 is a sectionalized plan and diagrammatic view of an alternative structure in accordance with the present invention; and

FIGURE 6 is a diagrammatic representation of a system incorporating a structure somewhat similar that of FIGURE 5.

Referring initially toFIGURE erally cylindrical transversely 1, there is shown a genbody 12 comprising the reed relay, 14 in one end 16 and a conductor 20 in the other end 18. The conductors A second current path through the body 12 is provided by a single integral conductor 26 passing through the body 12 parallel the conductors 14 and 20 and providductors 28, one pair and 20 of the body 12, provide shield members within the body 12.

Functionally, the illustrative component represented in FIGURE 1 switches current flow (open or closed circuit) between the conductors 14 and 20 in accordance with a tion 31 (FIGURE 2) as shown connecting tact 32' to the conductor 20, outside the enclosure 34.

Various forms of reed contacts are well known in the prior art. Generally they are formed of a strip of flexible or resiliently deformable paramagnetic metal and are shaped to be disconnected (FIGURE 2) when in a quiescent state. Upon the applica'tion of the switching current to the component, a magnetic switching field is developed and the contacts 30 and 32 move into aligned electrical contact.

The enclosure 34 housing the contacts 30 and 32 is of generally cylindrical configuration and may be formed of'glass, having glass-to-metal seals in the ends thereof to support the reed contacts 30 and 32 and pass them to their respective junctions 31. The solid conductor 26 (FIGURE 2) operates in cooperative relationship with the reed contacts 30 and 31, lies contiguous to the glass enclosure 34 and is encompassed by a cylinder 36 of insulating material of a flexible or resilient nature, e.g. Mylar. Concentric cylinders are then placed about the insulating cylinder 36 to provide spaced-apart co-axial shields in the component structure. More specifically, in their order of occurrence from the cylinder 36, the following cylinders are provided; a conducting cylinder 38; an insulating cylinder 40; a conducting cylinder 42 and an insulating cylinder 44.

The insulating cylinders all may be similar (in material and form) to the cylinder 36, e.g. comprising Mylar. The conducting cylinders 38 and 42 may comprise a conducting fiber or paper material which has a specific resistance across points in any given area relationship. One example of a material suitable for the cylinders 38 and 42 is manufactured by the Minnesota Mining and Manufacturing Company, and is designated resistance or conductive paper X1175. The use of conductive paper in this application is not only economical in cost and fabrication but also provides shielding of an effective nature in the structure hereof.

Pursuing consideration of the detailed structure of the component element, the conductive cylinders 38 and 42 are connected at each end to the conductors 28 for providing individual electrical contact outside the body 12. Additionally, a conductor 28a (FIGURE 2) extends through the body, parallel the cylindrical axis and between the cylinders 36 and 38, connected at both ends to the conductors 28.

Electrical conductors 22 and 24 (FIGURE 1) for carrying switching signals, are connected to a cylindrical coil 46 (FIGURE 3) provided outside the cylinder 44 in concentric relationship to the other cylinders. The coil 46 provides the magnetic field to displace the reed for switching operations.

The concentric electrical structure (FIGURE 2) as described above is housed or embedded in a closure 48 which may comprise epoxy resin or various other insulating materials. Thus, the structure is substantially isolated from the effects of ambient environments.

In the manufacture of the component as shown in FIGURES l, 2 and 3 the central structure may be formed as a sub-assembly providing the reed contacts 30 and 32 sealed in the glass enclosure 34 with connecting junctions 31 to the conductors 14 and respectively by using various well known techniques of the prior art. Next, the concentric cylinders may be provided about the enclosure 34 with the conductors 26 and 28a held in position therein. In this regard, a single wrap of the various materials considered may be provided wtih seams 50 as shown in FIGURE 3 to accomplish the cylinders. It may be desirable to angularly offset the various seams 50 to provide space compensation; however, such a consideration is only of incidental significance hereto.

The sheets forming the conductive cylinders 38 and 42 carry connection tabs 52 and 54 (FIGURE 2) at each end which are in turn connected to the ends of the conductors 28a and the interconnected conductors 28. More outputterminals 70. The transducer specifically, a conductive adhesive 55 is applied to. asmall area of the sheets comprising the cylinders 38 and 42 by which the conductive tabs 52 and 54 are then affixed to the cylinders. The tabs 52 and 54 may comprise small sheets of copper or other conductiversheets which provide a base connection for the conductors 28 and28a, This connection may be provided by soldering or' various other techniques well known in theprior art.

Upon completion of the. internaLcylindrical sub-assembly as described above, the coil 46 is telescopically positioned thereon. The coil may be pre-wound as a subassembly and placed on the cylindrical assembly, or it may be wound directly on the partial assembly. The coil 46 is connected to the energizing conductors 22v and 24 as previously explained. Next, the assembly is encapsulated within the closure 48 as with epoxy potting compound, so that the extending conductors lie outside the closure.

Thus, the component is completed and ready for use. As;indicated above, the reed contacts 30 and 32 (FIG- URE 2) are formed to lie spaced apart in the quiescent state of operation; however, upon application a sufficinet electrical current to the coil 46 through the conductors 22 and 24 (FIGURE 1) a magnetic field is established. which magnetizes the reed contacts 30 and 32 (FIGURE 2) moving them into aligned engagement and thereby closing the circuit between the conductors 14 and 20 (FIG- URE 1). Removal of the magnetic field, by halting current flow in the coils46, allows the contacts 30 and 32 to spread, opening the circuit.

Considering a particular circuit hereof utilizing the structure hereof, reference will now be made the diagram of FIGURE 4, which illustrates the shield elements as well as the active signal paths. The reed relay element as described above is schematically represented in the block 58, the reed contacts 30 and 32 being shown simply as a switch 60. In a similar schematic fashion, the coil 46 is represented as are the conductive cylinders 38 and The coil 46 (FIGURE 4) is connected through a switch 62 across a source of potential thatis applied to terminals 64. Therefore, closure of the switch 62 energizes the coil 46 to close the switch 68, thereby completing the signal path from a transducer 66, through an amplifier 68 to 66 is provided within a shield 72 (grounded through a capacitor 73)-which also encloses conductors 74 and 76, that extend to the conductors 14 and 26 respectively, as described with reference to FIGURE 1. The shield 72 is also connected to the cylinder 38 and then through conductor 28a. At the amplifier side, a shield 73 is provided over the amplifier 68 and conductors thereto. The shield 73 is connected to the through conductor 28a and the cylinder 38 and grounded along with the cylinder 42.

It is to be noted that the structure hereof enables the use of a ground return conductor, i.e. conductor 26, to be used as part of a signal return path thereby reducing the magnetic pickup from the operating coil which avoids reliance upon the shield structure as a ground return. This mode of operation is extremely effective in many applications operation with shields as described.

Regarding the avoidance of spurious signals in the conductors 14, 20 and 26 resulting from the energization'of the coil 46, an internal conductive cylinder 38 cooperatively acts as a secondary shield. In function, the second shield diverts a second set of shield currents, so that these currents do not enter the signal-carrying structure. As a result, significant improvement is provided.

In some applications, capacitive coupling between switch contacts has been found to be a problem. For example, When the switch 60 (FIGURE 4) is open, the reed contacts are capacitively coupled to a degree which has been recognized to present a problem. This difficulty can be avoided by utilization of an alternative embodiment involving critical signals, particularly in cohereof as shown in FIGURES 5 and 6 and as will now be considered in detail.

The external coil and shield structure for providing the magnetic field in the embodiment of FIGURE 5 and from the support 122 for mutual contact when the relay is not energized.

' shown, the shield and coil as previously described on the enclosure 92 the central placed about the various contacts.

When the relay is in an unenergized state with the two controlled paths therethrough open (contacts positioned of the reed contacts 110, 114, 112 and 116.

Of course, the concepts of the reed relay as illustrated be variously embodied gized.

The stationary contact 168 is connected to a movable contact 174 which comprises a double-throw switch with and 164. The contact 174 is also which engages the contact 156 when the relay is not energized.

to the shield 144 and to the contact 156. 1

In the operation of the system as shown in FIGURE 5, it is apparent that when the coil 142 is not energized (as depicted) the contacts 152 and 154 are not engaged. However, it is also apparent that ists from these contacts At a time when the relay coil 142 is energized by application of energizing coil, two electrostatic switches in the relay, and provision of a central section for terminating contact capacitance.

The system hereof also provides a unit which can be set forth below, forming a part of this application.

. 7 What iSclaimediis: i v p 1. A reed relay structure wherein at least one current path is controlled in accordance with control signals, comprising: a set of re d contacts adapted to be connected in said ,current path;

a magnetic coil means for controlling said reed con- I tactsto be opened and closed; p a first conductive shield fixed contacts; I I a second conductive shield fixed about said first conductive shield; and v insulation means for ohmically isolating said first and I said second conductive shields.

2. A reed relay structure according to claim 1 wherein said condi'lctive shields comprise cylinders of conductive P p r-i ,i V

3. A reed relay structure according to claim 2 further comprising connection leads affixed to said conductive paper and wherein said conductive paper has a resistance of at least ten ohms per inch. 4. A reedrelay structure according to claim I'further including a conductor extending substantially parallel to said set of reed contacts to be used as a part of the signal return path to reduce the magnetic pickup from the operating coil. p i

5. A reed relay structure according to claim 4 wherein said conductive shields comprise conductive paper having aresistance of at least 10 ohms per inch and further including terminal conductors atfixed to said conductive shields.

6. A reed relay structure according to claim 5 further including input signal means for providing a signal between said conductor and one of said reed contacts and further including means connecting said first shield.

about said set of reed 7. A reed relay structure according to claim 2 wherein said insulation means comprises a Mylar-like plastic material. i v

8. A reed relay structure according to claim 7, further comprising connection leads afiixed to said conductive paper and wherein said conductive paper has a resistance of at least ten ohms per inch; and further including a conductor extending substantially parallel to said set of reed contacts to be used as a part of the signal return path to reduce the magnetic pickup from the operating coil.

9. A reedfrelay'according to claim 1 including a plurality of sets of reed contactswhereby when said relay is open, certain of said reed contacts intermediate other of said reed contacts provide capacitive termination.

10. A'reed relay'according to claim 1 further comprisinga plurality of through conductors extending through said magnetic coil means.

I 11'. A reed relay according to claim 1 wherein a plurality of current paths-therethrough and therefore including additional setsof reed contacts.

12. A reed relay according to claim 11 including a plurality of sets of reed contacts whereby when said relay is open, certain of said reed contacts intermediate other of said reed contacts provide capacitive'termination.

References Cited UNITED STATES PATENTS 3.005069 10/1961 Sippach et al. 335-452 3,202,784 8/1965 Santangeli 200-153 XR 3,320,559 5/1967 Morrison 335-151 BERNARD A. GILHEANY, Primary Examiner. R. N. ENVALL, 1a., Assistant Examiner.

Claims (1)

1. A REED RELAY STRUCTURE WHEREIN AT LEAST ONE CURRENT PATH IS CONTROLLED IN ACCRODANCE WITH CONTROL SIGNALS, COMPRISING: A SET OF REED CONTACTS ADAPTED TO BE CONNECTED IN SAID CURRENT PATH; A MAGNETIC COIL MEANS FOR CONTROLLING SAID REED CONTACTS TO BE OPENED AND CLOSED; A FIRST CONDUCTIVE SHIELD FIXED ABOUT SAID SET OF REED CONTACTS; A SECOND CONDUCTIVE SHIELD FIXED ABOUT SAID FIRST CONDUCTIVE SHIELD; AND INSULATION MEANS FOR OHMICALLY ISOLATING SAID FIRST AND SAID SECOND CONDUCTIVE SHIELDS.

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