US3671892A

US3671892A - Wiping contact reed switch

Info

Publication number: US3671892A
Application number: US29156A
Authority: US
Inventors: Bruce G Eaton
Original assignee: Westinghouse Electric Corp; First Pennsylvania Banking and Trust Co
Current assignee: CBS Corp; First Pennsylvania Banking and Trust Co
Priority date: 1970-04-16
Filing date: 1970-04-16
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20

Abstract

A reed switch containing two reeds at least one of which is controlled by a means for producing a magnetic field. Each reed or beam is twisted along a longitudinal axis such that during operation the means for creating a magnetic field is disposed perpendicular to one of the resulting surfaces and pulls one reed into physical contact with the other in such a direction that the contact surfaces are flush. A wiping action follows between the faces of the contacting surfaces in a direction parallel to the planes of the contacting surfaces due to a component of motion in the direction of the minimum flexure axis of the moving beam.

Description

United States Patent Eaton, deceased June 20, 1972 [54] WIPING CONTACT REED SWITCH [2 l Appl. No.2 29,156

[52] US. Cl. ..335/l54 FOREIGN PATENTS OR APPLICATIONS 1,347,244 8/1964 France...'. ..335/l 51 Primary Examiner-Harold Broome Assistant Emminer-R. N. Envall. .Ir. Attorney-A. T. Stratton and C. L. McHale ABSTRACT A reed switch containing two reeds at least one of which is controlled by a means for producing a magnetic field. Each reed or beam is twisted along a longitudinal axis such that during operation the means for creating a magnetic field is disposed perpendicular to one of the resulting surfaces and pulls one reed into physical contact with the other in such a direction that the contact surfaces are flush. A wiping action follows between the faces of the contacting surfaces in a direction parallel to the planes of the contacting surfaces due to a component of motion in the direction of the minimum flexure axis of the moving beam.

9 Claims, 7 Drawing Figures WIPING CONTACT REED swrrcn BACKGROUND OF THE INVENTION Reed switches or telephone relay switches as they are sometimes known are usually quite small and encased in an envelope made of glass or some suitable electrically insulating material. The main reason for encasing the reeds is to keep dirt or detrimental environmental substances away from the contacting surfaces of the reed switch since they are so small that even the smallest bits of material can interfere with the switching action. In the past, reed switches were not constructed with a concern for the phenomena of wiping to remove particulate matter, in which the surfaces of the contacting points or butts are rubbed tangentially against each other to remove any dirt or grease which may be present. It was generally thought that the protection of the envelope was sufficient to keep dust and other particles away from the contacts such that the switch could function many times without fouling. However, it has been found desirable to extend a reed switch's life by having a built-in wiping action. This means that a switch built to operate a predetermined relatively large number of times can be made to operate even a greater number of times.

Other types of switches such as knife switches have employed wiping actions in which the movement of one contact against the other has been used to remove grease, dirt, etc. from the contacting surfaces. But because of their small size and the necessity for a relatively low cost, it has been impractical in the past to try to do this with a reed switch.

SUMMARY OF THE INVENTION In accordance with the invention, a typical reed switch is constructed. to provide a wiping action. Generally the reed switch is sealed within an electrically insulating or glass case to prevent dust and associated particles from building up on the surface of the contacting points. The reeds or beams of the disclosed reed switch act as conductors of electricity and respond to applied magnetic fields by moving to open and close the switch. The associated electromagnet is mounted external to the envelope of the switch. At least one reed or beam, because of inherent flexibility, acts like a cantilever member in the presence of the magnetic field applied and moves toward the other reed or away from it depending on the direction of the magnetic field. The reeds are connected through the envelope to outside terminals so that external circuitry can be connected and disconnected by the action of the opening and closing reeds or beams.

In the present invention, the problems of small size and economics are jointly solved by twisting at least one beam of the reed switch and orienting the controlling magnet such that the lines of magnetic flux are generally perpendicular to one flat surface of the twisted beam. The twist is made with respect to the contacting surface of the moving reed which remains parallel to the contacting surface of the other reed. As the magnetic force is applied, the part of the beam which is oriented perpendicularly to the direction of magnetic flux moves in the direction of the flux causing one contact surface to move toward the other contacting surface but on an angle with respect to it. The result is that one flat surface of the twisted beam does not contact the other flat surface in a perpendicular approach as with most types of reed switches but slides into it in an angular yet parallel approach. This can be likened to the way an aircraft approaches a runway during landing. In general, the attitude of the aircraft is oriented parallel to the runway though approaching it on a descending angle. This occurs because the rectangularly shaped beam has an axis of maximum flexure which allows the broadest side of the beam to bend or flex more easily than along its narrow side because of the inherent structural properties of the rectangular cross-sectional shape of the beam. It is for this reason that the broad or wide surface of at least one beam is oriented perpendicular to the lines of magnetic flux and as the magnetic force is applied, it easily flexes in that direction and causes contact to be made by the angularly displaced flat surfaces as previously described. However, once contact is made, the beam can no longer easily bend in the direction of the magnetic flux although it still has the propensity or tendency to move in that direction under the influence of the applied magnetic field. The only degree of freedom of motion remaining is in the direction of the narrow surface corresponding to the axis of minimum flexure. Motion in this direction causes the contacts to move or slide tangentially with respect to each other until a point is reached where the limit in elasticity along the minimum flexure axis prevents any further movement in that direction thus causing the beam to stop or cease moving in any direction regardless of the presence of the magnetic field and at that instant, the contact or closing cycle is completed. During an'opening operation, when the magnetic field or source of magnetic flux is removed or deenergized, the switch contacts are opened in a manner which is exactly the reverse of the closing operation just described.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a view of one example of a prior art reed switch;

FIG. 2 shows a partially cut-away side view of a reed switch illustrating a principal embodiment of the invention;

FIG. 3 shows a sectional view of the invention shown in FIG. 2 taken along line III-III in FIG. 2 prior to the start of the closing cycle when the switch is open;

FIG. 4 is a sectional view of the invention, similar to FIG. 3, at a time later in the closing cycle than that shown in FIG. 3;

FIG. 5 is a similar sectional view to those shown in FIGS. 3 and 4 at the end of the closing cycle;

FIG. 6 shows another embodiment of the invention; and

FIG. 7 is a sectional view of the embodiment shown in FIG. 6 shown along line VII-VII in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and FIG. 1 in particular, there is shown a prior art reed switch 8, in which a casing or envelope 10 made of any suitable dielectric or insulating material, such as glass, is used to enclose two reeds or beams 12 and 14. Beams l2 and 14 are flexible and each beam includes three separately identifiable sections or portions which are associated with it. Reed 12 has section 12a which is the anchoring end portion of the reed' 12 and is attached to the glass envelope 10 through an opening 16L in the glass envelope or enclosure 10. It may be attached by a glue or resin or merely by a pressure fit. Section 12a acts as both an anchor and a terminal. Section 12m is the main body of the reed or beam and is cantilevered outwardly from anchor section 12a and is flexible or springy, that is it can bend easily toward either the top or bottom of the glass envelope 10. Beam or flexible member 14 is constructed similar to beam 12. That is anchor or terminal section 14a is attached to envelope 10 at opening 16R and the main body of the beam 14m may also bend or flex similarly to beam 12. It will be noted that sections or portions and are the contacting points for this switch and respectively they form the third identifiable sections of each beam. Under the influence of a magnetic field perpendicularly oriented to

sections

12m or 14m, section or contact 12c will move toward section 140, or section or contact 14c will move toward contact 12c. Upon physical contact of the contacts 12c and 140, electrical continuity or a current carrying path will then exist between points 12a and 14a and of course any circuits which are attached to the associated terminals.

Referring now to FIG. 2, the reed switch 8' shown includes an ovaloid envelope 10' which is similar to the envelope 10 of switch 8 shown in FIG. 1. Envelope 10' may be substantially evacuated or filled with an inert fluid, such as argon to prevent oxidation.

Openings

16L and 16R in the envelope serve the same purpose as

openings

16L and 16R of envelope 10 shown in FIG. 1. In this embodiment of the invention, the switch 8' includes two

beams

18 and 20. Beam 18 is similar to beam 14 shown in FIG. 1 except that it is relatively shorter. It has an anchoring or terminal end or portion 18a which projects or extends through an opening 16R in the envelope 10 along a longitudinal axis 21R of the switch 8'. It also has a contact point or section 18c similar to contact point 140 of the switch shown in FIG. I. Contact point 18c may be more highly conductive than the rest of beam 18 to reduce contact resistance and may be smoothed to reduce friction. It will be noted, however, that main body portion 18m is much shorter than the main body portion 14m of the switch shown in FIG. I and it does not possess the inherent flexibility or springiness of main body 14m. Beam 18 is therefore relatively rigid and any flexibility in switch 8' is provided in beam or flexible member 20. Flexible or resilient member 20 is similar to flexible member 12 in FIG. 1 in that it has an anchoring end or terminal 200 anchored or screwed in a convenient manner to envelope 10' as it passes through the opening 16L. It also has a main longitudinal axis 21 and a second longitudinal axis, 21L in the vicinity of opening 16L, which is the longitudinal axis of anchor 20a. It has a contact point 200 at the opposite end of beam 20 away from the terminal end 200 which is disposed to engage contact point 18c and complete a circuit which extends between the

terminal sections

180 and 20a. One difierence between the reeds or

beams

12 and 20 is the extended or relatively greater length of beam 20 to compensate for the shortening of the associated beam 18. But the most significant structural difference between the

beams

12 and 20 is the twist in beam 20 indicated at 19R in FIG. 2 about longitudinal axis 21. The twist causes the main body 20m of beam 20 to be angularly displaced from the region or portion 200 about the longitudinal axis 21 of beam 20. This twist in beam 20 defines two angularly displaced planes, one of which is defined by the main body portion 20m of beam or lever 20 and the other of which is defined by the contacting surface or region 20c.

For a better understanding of the operation of the main embodiment of the invention, reference may be had to FIG. 3 which is a sectional view of the switch shown in FIG. 2. It will be noted that in this embodiment, enclosure or envelope 10' is generally cylindrical and circular in cross-section as illustrated although different cross-sectional shapes may be employed in other applications. Any enclosing surface capable of allowing magnetic flux to pass through while keeping dirt and small particles out is acceptable regardless of material or shape provided that the space inside the enclosure is sufficient to permit the motions necessary within it during the operation of the switch 8'. As can be seen in FIGS. 2 and 3, an electromagnet 22 is provided and its face is oriented or disposed parallel to the plane of the main body section 20m thus creating magnetic flux lines 23 which flow in generally parallel path through envelope l perpendicularly through or with respect to surface 20m. As magnetic field 23 is first applied to the switch 8', at the instant after electromagnet 22 has been energized so as to start to close relay 8', a force indicated by directional arrow or vector 24, having

components

28 and 26 act on the beam 20. It will be noted for the sake of simplicity that this force 24 is shown to act on the geometric center of beam 20 or on axis 21. Upon the first application of power to electromagnetic 22, and the subsequent creation of the magnetic field 23, beam 20 begins to move in the direction of force indicated by arrow or vector 24. The force indicated by arrow 24 can be resolved into two components at right angles to each other; one is a force component 26 which acts to bring flat contact surface 20c closer to flat contact surface 180. The other is a force component 28 which acts to move contact surface 20c tangentially with respect to contact surface 180. The net effect of this motion in the initial application of magnetic force is to move beam 20 along an oblique angle of direction with respect to beam 18 such that surface of contact 200 slides into or angularly approaches surface 18c in the general direction of arrow 24.

Referring now to FIG. 4, it will be noted that although the magnetic force 23 still exists, beam 20 has completed its movement in the direction of arrow 24, and engages or is butted flush against surface 18c at the contact surface 200. Surface or main part 20m of beam 20 has not been further distorted or twisted with respect to 20 by the application of the magnetic field and it is not the purpose of this invention to deliberately change the angle theta (0) of section or twisted region 19R as shown in FIG. 4 at any time during the operation of the invention although that may occur to a slight degree. Contact surface 20c has laterally been displaced a distance d with respect to contact surface when the switch 8' is closed as shown in FIG. 4.

Referring now to FIG. 5, the main advantage of the disclosed switch structure is illustrated. Even though the beam 20 has made initial contact as shown in FIG. 4, the force resulting from magnetic flux lines 23 has not diminished, and beam 20 still has a tendency to move in the direction of force component 24' because of the acceleration imposed upon it by the action of the magnetic flux 23. But it is restrained from moving in direction 24' by the stopping action of beam 18. The motion corresponding to force 24 can only be accomplished if the flexible beam or member 20 is caused to slide sideways or move laterally in a direction 28'. It will be noted that in order to do this, there must be a component of force in the direction 30 acting on beam 20. The force component 30 is along the minimum flexure axis 31 of beam 20 in section 20m. It will be noted by examining the two superimposed views of beam 20 shown in FIG. 5, that the beam 20 has moved an additional distance d from the position shown in FIG. 4. This distance is measured tangentially along surface 18c. The movement of beam 20 through the distance d causes the wiping action that is necessary to remove any residue on either

surface

200 or 18c or both. The main direction of movement of beam 20 during this wiping action is direction 28' because of the restriction of movement in direction 24' due to the presence of the blocking or stopping surface 18c. It is not to say that beam 20 does not move at all in direction 24 since beam 18 has some slight residual springiness. But the motion in direction 24' is severely limited when compared to the kind of motion that was shown in FIG. 3 and in fact a new component of motion 30 is introduced into the overall motion of the beam 20.

FIGS. 3, 4 and 5 considered together show that contact surfaces 20c and 180 engage or meet due to the motion of contact surface 20c in an angular path as it approaches surface 18c and upon engagement, contact surface 20c slides or moves in a direction 28' causing wiping of contact surfaces 200 and 18c. This wiping or removal of dirt and grease or any other foreign matter is one of the main advantages of the disclosed reed switch structure since it provides for better physical contact and thus the electrical resistance between the engaged surfaces 20c and surfaces 180 is minimized during the life of the switch 8.

FIG. 6 shows another embodiment of the invention in a switch 9 in which two beams or reeds 20' and 32 are displaced within envelope or enclosure 10''. The switch structure 9, differs from the switch structure 8 shown in FIGS. 2 through 5 in that beam 20' shown in FIG. 6 is shorter than beam 20 shown in FIG. 2 and that beam or reed 32 shown in FIG. 6 is generally longer and otherwise is structurally different from beam 18 shown in FIG. 2. The most significant difference between beam 32 and beam 18 is that beam 32 more closely resembles beam 20. In other words, the beam 32 has inherent flexibility of its own. Consequently both of the

beams

32 and 20 act in a similar manner during the operation of the switch 9. First, beam 20' is anchored in the vicinity of end 20a to glass envelope 10" at opening or hole 16L". Second, there is a main section or portion 20m which is attached to anchoring end 20a. Also, in the region 19R, beam 20' is twisted such that a new surface or plane offset by a predetermined angle 0 is formed, as indicated at 20c. Portion or section 200' is the contacting surface for beam 20'. In a like manner, beam 32 is attached in the vicinity of anchoring end or terminal portion 32a to envelope 10" at hole or opening 16R". Beam 32 also has a main body portion 32m, similar to main section or portion 20m of beam. There is a twist 32L in beam or reed 32 forming a new plane 32c. Preferably, this causes surfaces 32c and 200' to be aligned substantially parallel to each other for subsequent flush physical contact or engagement upon closure of reed switch 9. There are two electromagnets or magnetic devices associated with reed switch 9, one on the left associated with beam 20 which is the electromagnet 22 and one on the right associated with beam 32 which is electromagnet 25. Upon energization of the

magnets

22 and 25, beam 20' is pulled toward beam 32', while beam 32' is pulled toward beam 20 causing a quicker or faster closure of parallel contact surfaces 200' and 32c and for greater wiping action between said contact surfaces.

Referring now to FIG. 7, a sectional view of the reed switch of FIG. 6 is shown. Electromagnets 22' and 25 are shown with their respective magnetic fields 23' and 27. Electromagnet 25 is aligned substantially perpendicular to main body or section 32m of beam 32 and causes beam 32 to move in the general direction 48. This motion has a component 52 which is perpendicular to contacting surface 32c and a component 50 which is parallel to the surface 32c. Concurrently, magnet 22' is exerting a force on beam 20 causing main body or section 20m to move in a direction 44 with resulting component of force 42 which is perpendicular to surface 20c and a component of force 46 which is parallel to the surface 20c. The overall effect of the

electromagnets

22 and 25, is to move surfaces 32c and 20: toward each other in a parallel angled approach until'contact is made. When contact is made, the wiping efiect or action mentioned with respect to the switch 8' of FIG. 5 results except that both contacting members 32c and 200' have a tendency to slide or wipe tangentially with respect to each other. Beam 20' moves or is actuated to the left in a general direction 46, while beam 32 moves or is actuated to the right in direction 50. This creates a double tangential wiping motion which gives twice the wiping effect or action than if only one relatively movable beam were used as in the switch of FIGS. 2 through 5.

It is to be understood that with regard to either of the embodiments of the invention, the envelope indicated for example by 10 of FIG. 1 or 10'' in FIG. 6 can be of any general shape and of any kind of dielectric material and need not be evacuated. Its purpose is to protect the contacting surfaces from breakage during handling, detrimental environment, dust or dirt. It should also be realized that the angle theta (9) may be varied within a predetermined range in accordance with the invention. If the angle selected is very large, (such as approaching 90) there will be substantially no engagement between

surfaces

200 and 180 as shown in FIGS. 2 through 5 and if the angle selected is too small, such as approaching zero degrees, the switch operation will provide the advantages previously mentioned to a much lesser degree. The current carrying capabilities of the different embodiments of the invention described are limited by the surface remaining after wiping action has been completed. The electromagnets, such as 22 shown in FIG. 2 or 22' and 25 as shown in FIG. 6 may be of any standard type such as those generally associated with the reed switches. It should also be understood that general irregularities in contact surfaces have a tendency to cause friction which will retard the wiping motion as described in the previous embodiments of the invention. This, however, is not critical since, although contact friction cannot be completely eliminated it will, after a gradual wearing or seating of the contact surfaces, be reduced to a minimum. It should finally be noted that even with respect to beam 18 in FIG. 2 which is substantially inflexible, there is a slight flexibility in the direction of force 24, as shown in FIG. 3 and this is conductive to better wiping action as it allows beam 20 to move slightly more in direction 24 as shown in FIG. 5 which is of course more than would be allowed or pennitted had beam 180 been perfectly rigid.

The apparatus embodying the teachings of this invention have several advantages. For example, the disclosed switch structures are easily constructed and can be used to create a relatively simple contact wiping reed switch without the need for elaborate machining or mechanical operations. The twisting of the beam creates the angle theta (0) between the different portions of the beam structures which provides the contact wiping advantages in the operations of the switch structure previously described.

What is claimed is:

l. A reed switch comprising a plurality of elongated electrically conducting flexible members mounted within an elongated protecting envelope, said members each having an anchoring end, a contacting end and an intermediate main body, said anchoring ends being axially spaced and secured to the opposite ends of said protecting envelope and extending through and into saidprotecting envelope, a portion of each said anchoring end projecting outside of said protecting envelope to define an electrical terminal, said contacting ends being disposed in proximity to each other and to axially overlap, means disposed adjacent to said envelope for providing separate magnetic fields to generally interact with said main body only of one said members and to generally interact with no other member, said main bodies of said flexible members being capable of motion under the influence of said magnetic field, said main body for each member having a minimum flexure axis and a maximum flexure axis displaced from said minimum flexure axis and having a tendency to move in a first direction corresponding to the direction of said maximum flexure axis when said magnetic field is applied thereto, whereby said anchoring end remains generally stationary while said main body and said contacting end move in reaction to the application of said magnetic field, each said main body having a separate longitudinal axis perpendicular to said maximum and said minimum flexure axes, a portion of at least one of said members being displaced angularly along said longitudinal axis by a twist in said member between said main body and said contacting end, said main body of at least the lastmentioned member moving in said first direction when said separate magnetic field is applied to the main body thereof until said contacting ends of said members engage, said contacting ends being disposed substantially parallel to each other upon engagement, generally thereafter at least one of said members moving in a second direction whilev under the influence of said magnetic field thus causing a component of movement in said at least one of said members generally in the direction of the said minimum flexure axis only, said subsequent movement in said second direction causing at least one of said engaged contacting ends to move tangentially with respect to the other to thereby cause a wiping action between said contacting ends, the friction between said contacting ends during engagement being generally of a value which allows at least one of said contacting ends to move tangentially in said second direction, whereby the contacting end of another of said members acts as a stopping surface to substantially restrict the movement of said at lest one of said contacting ends to substantially only said second direction.

2. A reed switch comprising two elongated electrically conducting flexible members mounted within an elongated protecting envelope, said members each having an anchoring end, a contacting end and an intermediate main body, said anchoring ends being axially spaced and secured to the opposite ends of said protecting envelope and extending through and into said protecting envelope, a portion of each of said anchoring ends projecting outside of said protecting envelope to define a terminal, said contacting ends being disposed in proximity to each other and to axially overlap, said main bodies of said flexible members being capable of motion toward one another, a pair of means for producing two magnetic fields, one for each member with the magnetic field for each member substantially intersecting only the associated member, said magnetic field associated with each member generally interacting with said main body only of the associated member, said main body of each member having a minimum flexure axis and a maximum flexure axis displaced ninety degrees from said minimum flexure axis and having a tendency to move in a first direction corresponding to the direction of said maximum flexure axis in the respective main body when its said magnetic field is applied thereto, whereby said anchoring end remains generally stationary while said main body and said contacting end pivot about said anchoring end, each said main body having a longitudinal axis perpendicular to said maximum and minimum axes, said main body of each said members being displaced angularly with respect to said longitudinal axis by a twist in said member between said main body and said contacting end, said main body of each member moving in said first direction when said magnetic fields are applied thereto until said contacting ends of said members engage, said contacting ends being disposed substantially parallel to each other upon engagement, at least one of said members thereafter moving in a second direction, causing movement of said at least one of said members generally in the direction of the minimum flexure axis, while under the influence of said separate magnetic field, said movement in said second direction causing said at least one of said engaged contacting ends to move tangentially with respect to the other to thereby cause a wiping action between said contacting ends, said protecting envelope is hollow ovaloid in shape and is formed from an electrically insulating material, said envelope extending along an additional longitudinal axis, said anchoring ends being disposed generally symmetrically with respect to said additional longitudinal axis, said main body and contacting ends of both said members being comprised of elongated rectangular beams, said beams of said main bodies being joined to said respective anchoring ends, said main bodies of said members lying respectively in a first pair of parallel planes, said contacting ends of said members each lying respectively in a second pair of parallel planes angularly displaced from said first pair of parallel planes due to said twist in each said member, said parallel contacting ends being adapted to overlap upon engagement along said longitudinal axis of said envelope, said magnetic fields being axially spaced and applied on opposite sides of said envelope and being oppositely oriented generally perpendicularly with respect to said associated set of parallel planes of said main bodies to actuate said members toward and to engage one another in a first direction of motion in each case and to move thereafter in each case in substantially only a second direction.

3. The combination as claimed in claim 1, wherein said plurality of members comprises two members, a first of said members is relatively less flexible and longitudinally shorter than the other of said members, the other of said members being relatively longer and more flexible due to its greater length, said protecting envelope being hollow ovaloid in shape and formed from an electrically insulating material, said envelope extending along an additional longitudinal axis, said anchoring ends being disposed generally symmetrically with respect to said additional longitudinal axis, said main body and said contacting ends of both said members being comprised of rectangular beams, said beams of said main bodies being joined to said respective anchoring ends, only said other member having said twist between its said main body and said contacting end such that said contacting ends of both said members are disposed in generally parallel planes before motion while the main bodies of said members are not, said parallel contacting ends being adapted to overlap upon engagement along the said longitudinal axis of said envelope, only said other of said members being placed upon the influence of said magnetic field for inducing movement and upon contact only said other member moving in the said second direction to wipe said first member.

4. The combination as claimed in claim 2, in which at least one of said pair of means for providing said magnetic field comprises an electromagnetic adapted to be energized from a controllable source of electrical energy.

5. The combination as in claim 3, wherein said means for providing said magnetic field comprises an electromagnet adapted to be energized by a source of controllable electrical ener 6. f he combination as claimed in claim 1 wherein said protecting envelope is initially substantially evacuated of atmospheric material.

7. The combination as claimed in claim 1 wherein said envelope is substantially filled with an inert fluid.

8. The combination as claimed in claim 2 wherein said protecting envelope is initially substantially evacuated of atmospheric material.

9. The combination as claimed in claim 2 wherein said envelope is substantially filled with an inert fluid.

I i k i

Claims

1. A reed switch comprising a plurality of elongated electrically conducting flexible members mounted within an elongated protecting envelope, said members each having an anchoring end, a contacting end and aN intermediate main body, said anchoring ends being axially spaced and secured to the opposite ends of said protecting envelope and extending through and into said protecting envelope, a portion of each said anchoring end projecting outside of said protecting envelope to define an electrical terminal, said contacting ends being disposed in proximity to each other and to axially overlap, means disposed adjacent to said envelope for providing separate magnetic fields to generally interact with said main body only of one said members and to generally interact with no other member, said main bodies of said flexible members being capable of motion under the influence of said magnetic field, said main body for each member having a minimum flexure axis and a maximum flexure axis displaced 90* from said minimum flexure axis and having a tendency to move in a first direction corresponding to the direction of said maximum flexure axis when said magnetic field is applied thereto, whereby said anchoring end remains generally stationary while said main body and said contacting end move in reaction to the application of said magnetic field, each said main body having a separate longitudinal axis perpendicular to said maximum and said minimum flexure axes, a portion of at least one of said members being displaced angularly along said longitudinal axis by a twist in said member between said main body and said contacting end, said main body of at least the last-mentioned member moving in said first direction when said separate magnetic field is applied to the main body thereof until said contacting ends of said members engage, said contacting ends being disposed substantially parallel to each other upon engagement, generally thereafter at least one of said members moving in a second direction while under the influence of said magnetic field thus causing a component of movement in said at least one of said members generally in the direction of the said minimum flexure axis only, said subsequent movement in said second direction causing at least one of said engaged contacting ends to move tangentially with respect to the other to thereby cause a wiping action between said contacting ends, the friction between said contacting ends during engagement being generally of a value which allows at least one of said contacting ends to move tangentially in said second direction, whereby the contacting end of another of said members acts as a stopping surface to substantially restrict the movement of said at lest one of said contacting ends to substantially only said second direction.

5. The combination as in claim 3, wherein said means for providing said magnetic field comprises an electromagnet adapted to be energized by a source of controllable electrical energy.

6. The combination as claimed in claim 1 wherein said protecting envelope is initially substantially evacuated of atmospheric material.