US3426302A - Sealed reed switch with adjustable reed - Google Patents

Description

' Feb. 4, 1969 w A UNDENBERGER 3,426,302

SEALED REED SWITCH WITH ADJUSTABLE REED Filed Oct. 31, 1966 I F IG. 6 v lNl/ENTOA 6058 WA. L/NDENBERGER 2 I (en {LCM United States Patent 3,426,302 SEALED REED SWITCH WITH ADJUSTABLE REED William A. Lindenberger, Glendale, N.Y., assignor to Bell Telephone Laboratories, Incorporated, Murray Hill, NJ., a corporation of New York Filed Oct. 31, 1966, Ser. No. 590,896 US. Cl. 335-154 Int. Cl. H01h 1/66 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to switching devices, and particularly to so-called sealed switch contacts wherein at least one of two contactors enclosed in a sealed chamber is magnetically actuated into and out of electrical contact with the other, for completing electrical connections in telephone switching circuits.

In an especially suitable switch contact of this type, two magnetic reeds cantilevered from heat seals 'at opposite ends of a glass tube extend inwardly into the tube toward each others vicinity so that their flat surfaces face each other across a gap. A magnetic field applied to the tube bends the reeds against their inherent resilience and into alignment until they close the gap. By extending the reeds outwardly from the heat seals, electrical circuits connected to the reeds may thus be joined. Removing the magnetic field permits the resilience of the reeds to open the gap and disconnect the outside circuits.

To obtain low impedance connections and reliable operation with such contacts, the reeds must be spaced and oriented accurately. This accuracy requires holding the reeds in their exact ultimate positions relative to each other throughout the operation that forms the heat seals. Failure to do this often results in contact rejects. Thus manufacture of such switch contacts is time-consuming and expensive.

The overall structure and the requisite accuracy also impose special shapes and close tolerances on the reeds. Within the glass tube the reeds must have suitable flat contact surfaces. On the otherhand, at the heat seals the reeds must exhibit a round cross section about which molten glass can flow and cool if the glass is to remain as strain-free as possible. The contact structure demands from the reeds that, in addition to their essential magnetic and electrical properties, they also possess heat expansion coefiicients compatible with glass-to-metal seals. This combination of requirements often involves comprising these electrical, magnetic or mechanical properties.

Such switch contacts are also susceptible to breakage when even light shocks are applied to the glass tubing.

An object of this invention is to improve such sealed switch contacts and to simplify their process of manufacture.

Another object of the invention is to improve the character of reed performance by permitting materials of improved magnetic and electrical qualities while nevertheless avoiding deleterious effects in the glass-to-metal seals.

Still another object of the invention is to eliminate the effect of flowing glass and its ultimate cooling position upon the cantilever position of the thus-supported reed.

Still another object of the invention is to eliminate the criticality of the heat-sealing operation, as well as the 3,426,302 Patented Feb. 4, 1969 criticality of alignment and rotation of the reeds during sealing, upon the ultimate gap and operation of the switch contact.

Still another object of the invention is to simplify the reed for contacts of this type.

According to a feature of this invention, these objects are obtained in whole or in part by extending the glass tube with a soft metal sleeve one of whose ends is heatsealed to an open end of the glass tube and the other of which surrounds the reed and cantilevers it inwardly from a flange which is formed by crimping the end of the sleeve about a portion of the reed and welding it. According to the invention, the reed is adjusted relative to another contactor in this tube by flexing the flange that cantilevers the reed. The sleeve serves as a terminal for connection to outside electrical circuitry.

According to another feature of the invention, the reed comprises a flat strip cut from a sheet of magnetic material coated at least on one side with a precious metal contact material. 7

Still another feature of the invention involves locating the interior end of the reed so cantilevered from the sleeve in a gap between two other conductive members extending into the glass-surrounded chamber and adjusting the sleeve so that the reed in a magnetized state touches one but not the other conductive member.

By virtue of these features, particularly the sleeve, the internal position of the reed may be adjusted even after assembly, by moving the flange. These features also eliminate the need to make the reed material compatible with a glass-to-metal seal. A greater degree of latitude in materials and structures is thereby possibly without sacrificing the quality of operating characteristics.

These and other features of the invention are pointed out in the claims. Other objects and advantages of the invention will become apparent from the following detailed description when read in light of the accompanying drawing wherein:

FIGS. 1 and 2 are respective plan and elevatio? sectional views of a switch contact embodying features of the invention;

FIGS. 3 and 4 are respective plan and elevation sectional views of another switch contact embodying features of the invention;

FIG. 5 is a section of still another embodiment of the invention; and

FIG. 6 is a section of the reed in FIG. 5.

In FIGS. 1 and 2 the ends of a cylindrical glass envelope or tube 10 embrace and support, by means of heat seals 12, two axially projecting metal sleeves 14 and 16.

The outer ends of the sleeves 14 and 16 are crimped and welded shut to form flanges 18 and 20. They are also welded about and to the rod- shaped handles 22 and 24 of respective magnetizable and conductive contact reeds 26 and 28. The latter form flat paddles 30 and 32 whose ends face each other across a contact gap 34. Connection from an outside circuit to the contact may involve soldering wires either to the handles 22 and 24 at their exposed ends or directly to the sleeves 14 and 16. In the latter case the handles outer ends may be clipped off at the flanges 18 and 20. In the embodiments of the invention illustrated in FIGS. 1 and 2, handle 22 is clipped ofi. Handle 24 passes through the flange 18.

The sleeves 14 and 16 are composed of a metal having expansion characteristics compatible with lead glass, such as Niron 52. Niron 52 is a trademark of the Wilbur B. Driver C0. of Newark, N.J., for a nickel-iron alloy containing about 52. percent nickel. The reeds are made of a resilient magnetic material, one whose heat expansion charatceristics need not be compatible with lead glass, such as Remendur or Perminvar. Remendur and Perminvar are trademarks of the Wulbur B. Driver Co. of Newark, N.I., for nickel-iron-cobalt alloys. Preferably, the reeds inner facing ends are coated with a layer of gold and silver alloy to form the contact covers 36 and 38. Such reeds are illustrated in U.S. Patent 3,251,121 of K. B. Prival, issued May 17, 1966.

Exemplary magnetic actuating means for the contact illustrated in FIGS. 1 and 2 appear in US. Patent 3,005,072 of J. T. L. Brown, dated Oct. 17, 1961. This involves applying to the contact a magnetic field. The magnetic properties of the reeds 26 and 28 cause the paddles to bend resiliently until their coated ends touch. This closes the gap 34. A continuous electrical connection then exists between the handle 22 and the handle 24 through the paddles 30' and 32. This closes any electrical circuit connected to the sleeves or reeds. Eliminating the magnetic field releases the reeds 26 and 28 so that by virtue of their natural resilience they return to the positions illustrated in FIGS. 1 and 2. This opens the gap 34 and any circuit connected to the sleeves or reeds.

According to another embodiment of the invention, the reeds are composed simply of flat strips cut from sheet stock having a magnetic substrate such as Remendur or Perminvar, coated on one or both faces with layers of the gold-silver alloy of the covers 36 and 38. This embodiment is illustrated in FIGS. 3 and 4. Here, two such flat reeds 39 and 40 are cantilevered from the flat flanges 18 and 20 of the sleeves 14 and 16 'between which they are also welded. The substrates 41 and 42 of the reeds hold the layers 44 and 46 so that the latter face each other across the gap 34. It is possible for the rectangular cross section of the reeds 39 and 40 to extend completely throughout their lengths even at the sleeves end. This is so because the glass seals 12 need not flow about the reeds rectangular configuration. They flow only about the round configuration at the inner ends of the sleeves 14 and 16. Making reeds flat throughout represents a considerable saving in their manufacture. Electrical contact may be made either to portions of the reeds 39 and 40 extending through the flanges 18 and 20 or directly to the sleeves 14 and 16. In the latter case, the reeds ends beyond the flanges may be cut off. To illustrate both possibilities in FIGS. 3 and 4, the reed 39 is shown passing through the flange 18 while the reed 40 is shown clipped ofl.

A suitable manufacturing sequence for assembling the contact of FIGS. 1 to 4 involves inserting the ends of the sleeves 14 and 16 into the ends of the tube 10, and inductively or otherwise heating the glass tube at its ends while simultaneously heating an end of each sleeve 14 and 16. Heating continues until a suitable glassto-metal seal obtains. The reeds 26 and 28 or 39 and 40 are positioned inside the thus-formed tube and sleeve assembly in the approximate position shown in FIGS. 1 and 2. A clamp crimps the outer end of the sleeves 14 and 16 at the locations 18 and 20 onto the handles 22 and 24 of the reeds 26 and 28 or onto the outer portions of reeds 39 and 40. A welding device closes the crimped-down flanges about the handles 22 and 24. This seals the interior of the chamber from ambient air. If desired, suitable evacuating means or gas-pumping means may evacuate, or pressurize the contact with inert gas, before or after the crimp-ing operation. It is possible also to perform the crimping operation prior to the heatsealing operation.

After completion of assembly, the gap 34 may be set bytwisting the flanges 18 and 20 that cantilever the reeds 26and 28 or the reeds 39 and 40 relative to the glass tube 10 and each other. Where desired the reed portions extending beyond the flanges, and even a portion of the flanges may be clipped off. Clipping the flanges prevents accidental reed reset.

The sleeves 14 and 16 serve to shield the precious metal layers 36 and 38 from the effects of the final sealin operation which may constitute the welding operation if that is last, or the glass-to-metal seal operation if that is chosen to be last. Since the sleeve material need not possess both spring and magnetic qualities which inhere in the reeds 26 and 28 or the reeds 39 and 40, a more substantial glass-to-metal seal is available from the variety of materials which can be chosen for this purpose. Moreover, the sleeves 14 and 16 separate the seals 12 from the reeds so that the sealing operation has no substantial effect upon the position of the ends of the reeds near the gap 34.

As a further point, the sleeves 14 and 16 permit adjusting the contact after sealing and avoiding any hitherto necessary demagnetization of the reeds 26 and 28 during the heat-sealing process in order to set the gap 34. Adjustment of the reeds is possible not only in the up-anddown direction shown in FIG. 1 but also rotationally and in the side-to-side direction. This permits use of reeds with a wider range of rotary longitudinal and lateral alignment. In fact, adjustment may be made while the contact is subject to its operating magnetic field. The soft metal sleeves 14 and 16 also are capable of absorbing shocks applied to the assembly of FIGS. 1 and 2.

These advantages of the invention also inure to the embodiment of the invention shown in FIG. 5. Here, in operation a single reed 50 responding to an applied magnetic field travels across a gap 52 from one stationary contactor 54 to another stationary contactor 56. When the magnetic field is removed resilience of the reed 50 returns it across the gap to contact the terminal 54. The reed 50 may be the type illustrated in FIG. 1 as 26 or 28 or it may comprise a flat substrate 58 covered on both sides with the gold-silver alloy cover 60. The alloy composition is described in the above-mentioned Prival Patent 3,251,121. The reed preferably is cut from preplated sheet stock. It extends through a sleeve 62 whose flange 64 has been crimped and welded together about the reed 50. The uncrimped circular portion of the sleeve 62 is heat-sealed at seals 66 to a glass envelope 68 surrounding the assembly. Seals 70 secure the contactors 54 and 56 in position. However, sleeves such as 62 may also be used to hold these contactors.

The switch contact of FIG. 5 is manufactured by inserting or positioning the sleeve 62 and the contactors 54 and 56. Suitable heaters such as inductive heaters simultaneously heat these elements as well as the ends of a glass tube until the seals 70 and 66 form as shown in FIG. 5. The gap 52 can now be adjusted by inserting an instrument through the sleeve 62 to pry apart and otherwise position the terminals 54 and 56. Preferably these terminals are positioned together closer than finally required if this prying operation is included. The manufacture continues by inserting the reed such as shown either in FIG. 1 or in FIG. 6, crimping the sleeve 62 and welding the thus-formed flange together with the end of the reed 50. Either before the crimping or after, the chamber formed by the glass tube 68 is pressurized or evacuated as necessary. The position of the reed is now adjusted by twisting the flange 64. The configuration results in a magnetically-operated, double-throw switch contact. Its advantages are substantially the same as those for the embodiments of FIGS. 1 to 4.

While embodiments of the invention have been described in detail, it will be obvious to those skilled in the art that the invention may be embodied otherwise without departing from its spirit and scope.

What is claimed is:

1. A magnetically actuable switch contact comprising envelope means, metal sleeve means heat-sealed to an end of said envelope means and extending outward-1y therefrom, said sleeve means having an outer end forming grasping means, a magnetizable and electrically conductive contact reed cantilevered from said grasping means and extending through said sleeve means and terminating inside said envelope means, and conductive means projecting into said envelope means and extending to a position at which said reed may contact said conductive means when said reed is flexed by a magnetic field, said metal sleeve means where said reed extends therethrough having an interior diameter sufliciently larger than the dimensions of said reed transverse to reed length to form a clearance within which said reed may flex from said grasping means, said clearance being sufliciently large so said reed may respond to a magnetic force by flexing Within the clearance and moving one end of the reed to a flexed position in contact with said conductive means from a rest position out of contact with said conductive means.

2. A contact as in claim 1 wherein said conductive means include a second reed, second sleeve means grasping said reed with a flat grasping means, said second sleeve means being heat-sealed to said glass tube at the end opposite said grasping portion, said grasping means of said second sleeve means extending outside of said tube.

3. A contact as in claim 1 wherein said grasping means are welded together about said reed and to said reed, said clearance being further large enough to permit said reed while magnetically unstressed to move transverse to the reed length and within said clearance over an adjustment range in response to mechanical flexing of said sleeve means at said grasping means.

4. A contact as in claim 1 wherein said reed comprises a paddle-shaped portion extending into said envelope means and a rod-shaped portion extending into said grasping means.

5. A contact as in claim 1 wherein said reed comprises a flat strip having a magnetic substrate material and a precious-metal overlayer on said substrate.

6. A contact as in claim *1 wherein said conductive means comprise two contactors projecting into said envelope means, one of which remains in contact with said reed when said reed is magnetized and the other of which contacts said reed when said reed is not magnetized.

7. A contact as in claim 2 wherein each of said reeds comprise a substrate of magnetic material and an overlayer of precious-metal conductive material and wherein said reeds are positioned so said overlayers of conductive material face each other and contact each other when said reeds are magnetized.

8. A contact as in claim 6 wherein said reed comprises a substrate of magnetic material and two contact layers on opposite sides of precious-metal conductive material, said reed being of strip-shape and having said layers facing said respective contactors.

References Cited UNITED STATES PATENTS 3,032,628 5/1962 Ellwood 335154 3,165,608 1/1965 Wallace 335154X 3,250,875 5/1966 Wintriss 335-151 3,261,939 7/1966 Prival -l54 3,292,122 12/1966 Beli 335154 BERNARD A. GILHEANY, Primary Examiner.

ROY N. ENVALL, JR., Assistant Examiner.

U.S. Cl. X.R. 29622

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