Magnetically Actuatable Reed Switch Assembly

Abstract

A reed switch assembly of the type comprising a pair of spaced-apart flexible magnetically permeable electrically conductive reeds adapted to contact each other when brought into proximity to magnetic flux. Herein, the magnetic flux is supplied from a permanent magnet formed of permanently magnetized particles distributed throughout a structurally continuous flexible resinous matrix, said permanent magnet-means being annularly C-shaped and resiliently constrictable and being employed in the switch assembly under conditions of unrelieved constricted stresses.

Description

With magnetically actuatable reed switch assemblies of the prior art, the permanent magnet means invariably comprises magnetized metallic particles sintered directly together, such sintered permanent magnets being expensive to manufacture and being exceedingly difficult to alter in size or shape. Moreover, when a plurality of such prior art switch assemblies are banked in close quarters, as in a keyboard installation, there is apt to be a magnetic interference from the magnet means of neighboring switch assemblies whereby malfunction of a given switch assembly might result.

It is accordingly the general object of the present invention to overcome the disadvantages and deficiencies of the prior art magnetically actuatable reed switch assemblies, particularly those that utilize sintered particles permanent magnets. These general objects are attained by employing a novel C-shaped resiliently constrictable magnet means comprising magnetic particles distributed throughout a structurally continuous resinous matrix, said C-shaped resinous magnet means being readily reduceable in gravimetric mass appropriate to manufacturing and installation exigencies and being utilized within the switch assembly under conditions of unrelieved constriction stresses with a support means.

In the drawing, wherein like characters refer to like parts in the several views, and in which:

FIG. 1 is a perspective view of a representative embodiment "T" of the magnetically actuatable reed switch assembly of the present invention.

FIG. 2 is a sectional elevational view taken along lines 2--2 of FIG. 1.

FIG. 3 is a sectional plan view taken along lines 3--3 of FIGS. 1 and 2.

FIG. 4 is a perspective detail view of the representative support means for the C-shaped resiliently constrictable magnet means.

FIG. 5 is a perspective detail view of the C-shaped resiliently constrictable magnet means employed in the switch assembly "T" of FIGS. 1-3.

FIG. 6 is a sectional elevational view taken along lines 6--6 of FIGS. 5 and 7.

FIG. 7 is a perspective detail view of the FIG. 5 magnet means schematically showing alterability, e.g., shortening, of the circumferential length thereof.

Representative reed switch assembly "T" is herein uprightly disposed along a longitudinal axis 9, said assembly "T" comprising a plurality of components and herein including; elongate reeds unit 30 including elongate flexible reeds 32 and 33 extending along axis 9; an external elongate housing herein including elongate tubular casing 10 with an open forward end 13 and further including a transversely extending rearward resinous plug 15; a C-shaped resiliently constrictable permanent magnet means 50 substantially surrounding axis 9 and having a pair of transversely extending ends including a forward end 56 and a rearward end 57 of opposite magnetic polarities, herein forward end 56 being arbitrarily selected as "North" or "N"; a pushbutton 21 extending forwardly of the housing forward end 13 and having spring means, e.g., 80, whereby the pushbutton is resiliently rearwardly depressible along axis 9, said pushbutton being longitudinally actuatably associated with the C-shaped magnet means 50; and a transversely rigidly dimensioned support means 25 for the C-shaped magnet means 50, the pushbutton 21 herein being integrally connected to the support means 25 to provide unitary component 20 of FIG. 4.

Referring now to FIGS. 5 and 6. The C-shaped resiliently constrictable magnet means 50, as shown in solid line in FIG. 5 for its normal nonconstricted form, has a pair of free ends 51 and 52. The cross-sectional shape as indicated in FIG. 6 is regularly rectangular. The structural material for the magnet means comprises magnetic particles 59, such as iron, iron oxide, nickel, etc., said magnetic particles 59 being distributed throughout a structurally continuous flexible resinous matrix, such as rubber. This particles and resinous matrix type magnet structure is permanently magnetized so that the forward end 56 thereof is of opposite magnetic polarity to the rearward end 57, said rearward end 57 being arbitrarily selected as "SOUTH" or "S." The C-shaped magnet means 50 is resiliently constrictable by virtue of the flexible resinous matrix, and as indicated in phantom line in FIG. 5, the free ends 51 and 52 might be brought closer together, even to the extent of actual physical contact if so desired. There is, of course, unrelieved flexural stress within magnet means 50 when made to assume a resiliently constricted form, said magnet means having some regular external radius r from axis 9 when in the said artificially constricted form.

As indicated in FIG. 7, the magnet means 50, having an easily clippable or sliceable resinous matrix as the major volumetric proportion thereof, can be readily reduced in peripheral circular length, appropriate to the selected dimensional requirements of the switch "T." For example, when selecting smaller diameter reed envelopes 31, a portion at 52 might be removed to provide a new second free end 52C, and thus, an appropriately smaller constricted radius r might be attained commencing from the same original size magnet means 50. Such selectable shortening of the C-shaped magnet means 50 also provides a convenient means for reducing the gravimetric mass thereof appropriate to the use conditions of switch assembly "T." For example, when a large number of switch assemblies "T" are banked very closely together, as in a keyboard-type installation, one or more individual switches might misfunction because of magnetic interference from neighboring switches. However, with the readily clippable particles and resinous matrix magnet means 50 herein, the gravimetric mass thereof can be easily altered in one or more of the banked switches, whereby problems of inimical magnetic interference can be readily corrected. As will be explained later in greater detail, the C-shaped annular magnet means held in the said constricted state thereof (as by support means 25) substantially surrounds and is transverse to axis 9 and to a first flexible reed 32.

There is a pair of ferric or similar "magnetically permeable" flexible elongate reeds 32 and 33 disposed in substantially colinear relationship along axis 9, said flexible reeds being separated by a finite spatial gap at the free end of one reed. At least one of the two reeds is sufficiently flexible that said reeds will physically contact each other (as indicated in phantom line in FIG. 2) when subjected to magnetic flux (as when magnet means 50 is at its rearward second station at which 29 contacts 16 as indicated in phantom line in FIG. 2). At the forward first station for magnet means 50 (spring 80 forces support means floor 26 against casing neck 12 as indicated in solid line in FIG. 2), the magnet means 50 is said finite distance "FD" forwardly remote from the magnet means second station and there is an electrically nonconductive spatial gap between flexible reeds 32 and 33. In normal commercial practice such reeds 32 and 33 are encased as a reeds unit 30 in an elongate envelope 31 of glass or similar relatively "magnetically impermeable" material. There is a flexible elongate conductor wire 34 attached to the forward end of reed 32, forwardly of envelope 31, and electrical conductor 34 extends rearwardly of housing resinous rearward plug 15 through perforation 18 thereof. Reeds unit 30 is uprightly supported along axis 9 by the forward contour of housing rearward plug 15 and the rearward portion of reed 33 extends rearwardly of plug 15 through perforation 17 thereof.

As has been already alluded to, the housing has an open forward portion 12 to slidably accommodate a pushbutton, e.g., 21, the said housing comprising a casing portion 10 and a rearward resinous plug portion 15. Casing 10 has two integrally connected tubular parts, each herein circularly concentric about axis 9, and including the major length and larger diameter body 11 with lower transverse end 14 and the minor length and smaller diameter neck 12 with upper forward transverse end 13. Rearward plug 15 has a forward annular extremity 16 forwardly of 14, and 29 is abuttable against 16. Plug 15 has an annular shelf 19 surrounding axis 9, and helical spring 80 surrounding axis 9 extends forwardly from 19 and bears against magnet means rearward side 57. Thus, as pushbutton 21 (which is longitudinally coreciprocatably attached to magnet means 50) is moved along axis 9 relatively rearwardly of casing forward end 13 for said finite distance "FD," the magnet means 50 moves against helical spring means 80 to the phantom line second station whereupon the flexible reeds 32 and 33 are made to contact each other.

While several types of support means to maintain magnet means 50 in constricted condition might with equal facility be employed, the support means 25 is especially advantageous, especially since it lends itself to the FIG. 4 unitary overall combination 20 along with pushbutton 21. Support means 25 comprises a centrally open transverse floor plate 26 having the central opening 24. A vertical circular wall 28 surrounding axis 9 is attached to the lower rearward side of member 26, circular wall 28 having a rearward lower extremity 29 annularly surrounding axis 9. Moreover, circular wall 28 has an outside surface 28B, and has an inside surface 28A spaced a constant radial distance r from axis 9. Thus, it can be seen that the outside upright surface 50B of magnet means 50 is in continuous contact with upright inside surface 28A whereby magnet means 50 under conditions of unrelieved constriction stresses is so supported by the transversely rigidly dimensioned circular wall 28. Tubular pushbutton 21 has a closed forward end 23 and a longitudinal bore 24 extending rearwardly of 23 for a distance exceeding "FD" whereupon the rearward extremity of pushbutton 21 is at and attached to transverse plate 26.

It can be readily appreciated from FIG. 2 that switch "T" would be assembled in the following order; forward end 23 of unit 20 is inserted through casing 10 commencing at 14; magnet means 50 is cut to the proper circular peripheral length, and is then constricted to radius r and placed within support means 25; then, forward end 23 of unit 20 is inserted forwardly along axis 9 commencing at 14; then, spring 80 is inserted into 11 through 14; and finally plug 15 together with reeds unit 30 mounted therein is forwardly moved into place against 14.

Having now described a representative embodiment of the magnetically actuatable reed switch assembly, it is desired to claim the generic and specific concepts thereof as follows.

Claims

I claim:

1. A magnetically actuatable reed switch assembly to control the flow of electrical current between at least two distinctly separated reeds, said magnetically actuatable reed switch assembly comprising:

A. a pair of magnetically permeable flexible elongate electrically conductive reeds disposed in substantially colinear relationship along a longitudinal axis, said flexible reeds being normally separated by a finite spatial gap at a first reed free end, at least one of said reeds being sufficiently flexible that said reeds will be brought closer together when subjected to magnetic flux;

B. a transversely C-shaped and transversely resiliently constrictable magnet means substantially surrounding said reeds, said magnet means being adapted to reciprocate along the longitudinal axis and including a first station therefor relatively remote from the first reed free end at which first station said reeds remain spatially separated and further including a second station therefor located nearer to said first reed free end at which said second station the magnetic flux of the said permanent magnet means diminishes the interreeds spatial gap, the first and second stations being longitudinally separated by a finite distance, said magnet means having two transverse ends of opposite magnetic polarities including a "North" pole and a "South" pole, and C-shaped magnet means under conditions of unrelieved constriction stresses being supported against the transverse floor plate of a transversely rigidly dimensioned longitudinally reciprocatable support means;

C. a housing surrounding said longitudinally reciprocatable support means for the magnet means, said housing including a rearward end and an open forward end; and

D. a pushbutton disposed within and extending forwardly from the housing open forward end, said pushbutton extending rearwardly into the housing and being longitudinally reciprocatably actuatably engaged with the support means, the longitudinal reciprocatability for the pushbutton being at least equal to said interstations finite distance.

2. The magnetically actuatable reed switch assembly of claim 1 wherein the said pair of reeds are supported within an elongate envelope of relatively magnetically impermeable material; wherein the resiliently constrictable C-shaped magnet means comprises permanently magnetized particles distributed throughout a structurally continuous matrix of a resiliently flexible resinous material; wherein the support means comprises a centrally open floor plate positioned substantially normal to the longitudinal axis and an integrally connected circular upright annular wall portion having a uniform upright height, said annular wall having a circular upright inside surface spaced a constant radial distance from the longitudinal axis; wherein the constricted magnet means has a C-shaped upright outer wall in continuous contact with the support means upright inside surface; wherein the upright pushbutton is tubular surrounding the longitudinal axis and attached to the support means floor at the central opening thereof, the pushbutton bore having an upright length exceeding the interstations finite distance; and wherein an upright helical spring surrounds the longitudinal axis for resiliently normally urging the support means and the magnet means toward one station.

3. The reed switch assembly of claim 2 wherein the major volumetric fraction of the magnet means comprises the resinous matrix whereby said magnet means can be readily altered in peripheral length; and wherein the helical spring is disposed rearwardly of the magnet means.

4. A plurality of the magnetically actuatable reed switch assemblies of claim 3 banked together in a keyboard installation, each of said reed switch assemblies being identical in every structural and dimensional detail except that the gravimetric mass for the C-shaped resiliently constrictable magnet means differs so greatly from one reed switch assembly to the other that such gravimetric mass differential is readily visually apparent to the naked eye.