Bistable Reciprocable Switch Construction

Abstract

A reciprocable switch comprises a contact carrier movable to either of two operating positions in response to a cycle of operation of a pushbutton and in which the carrier is stable in either of its two positions. The carrier is coupled to a oscillatory actuator which is rockable between two extreme positions. The actuator supports an index slide which is straddled by indexing barbs carried by the pushbutton, engagement of the slide by one barb effecting rocking of the actuator from one position to the other. A spring urges the pushbutton to a normal position, maintains the carrier and the actuator in stable positions, and effects shifting of the slide from a position in which it is engageable by one of the indexing barbs to a position in which it is engageable by another of the indexing barbs. The parts of the switch are contained in a casing which removably may be fitted to a support on which the fixed contacts are mounted.

Description

The disclosed invention relates to an electrical switch having a pushbutton operator movable cyclically from a normal, projected position to retracted position and return, the pushbutton operator including means for indexing a movable contact carrier on alternate strokes from one position to another so as to enable movable contacts to engage and disengage selected fixed contacts. Pushbutton operated switches are well known in the art and generally are of two kinds. One kind operates on a two-stroke cycle wherein movement of the operator from a normal position to a retracted position either makes or breaks a circuit, and return movement of the operator to its projected position either breaks or makes such circuit. In the other kind of known pushbutton switch, the operation is the same as that just described, but the operator may be provided with means for latching it in its retracted position so as to maintain the movable contacts in a selected position corresponding substantially to that which they occupy when the operator is in its retracted position. In most switches of the latter construction, the latching means is effective only in response to partial return movement of the operator to its retracted position. In such constructions, the force applied on the movable contacts to maintain them in the selected position thus is less than that which is applied to them when the operator is in its fully retracted position. It is possible, therefore, that the decrease in force will permit some looseness or undesirable instability of the movable contacts, which may result in arcing or pitting of the contacts.

Pushbutton switches in general use heretofore usually have been self-contained in the sense that the movable and fixed contacts are supported within the same casing. There are many instances, however, especially in constructions utilizing printed or integrated circuits, when the fixed contacts are carried by a substrate or base. In such constructions switching can be effected by the provision of movable contact means only if they are associated with and properly oriented to the substrate and to the fixed conductors supported thereby.

An object of this invention is to provide a pushbutton operated switch having a contact carrier movable between two positions in either of which the carrier is maintained in an equally stable condition.

Another object of the invention is to provide a pushbutton-operated switch wherein the indexing of the contact carrier from one position to the other is effected by positive engagement between indexing means, rather than by reliance upon springs or other resilient means.

A further object of the invention is to provide a switch of the character described and wherein a single spring controls the pushbutton operator and the indexing means, and yieldably biases the contact carrier so as to maintain the latter in the position to which it has been moved.

Another object of the invention is to provide a pushbutton-operated switch provided with means for separably mounting it in an operative position on a support for fixed contacts.

Other objects and advantages of the invention will be pointed out specifically or will become apparent from the following description when it is considered in conjunction with the appended claims and the accompanying drawings, in which:

FIG. 1 is an isometric view of an assembled switch constructed in accordance with the invention;

FIG. 2 is an enlarged, transverse sectional view of the switch and illustrating the contact carrier in one of its two positions of adjustment;

FIG. 3 is a view similar to FIG. 2, but illustrating the contact carrier in its other position of adjustment;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 2, but with the power spring omitted; and

FIG. 5 is a sectional view taken on the line 5-5 of FIG. 4.

A switch constructed according to the invention comprises a casing 1 formed of nonconductive material having parallel sidewalls 2 and parallel end walls 3 defining a chamber 4 open at both its top and bottom. Within the chamber 4 is an actuator body 5 formed of nonconductive material having a depressed, flat center section 6 terminating at its opposite ends in upwardly diverging walls 7 which, in turn, terminate in vertical walls 8. At the upper end of each wall 8 is a stub shaft 9 that is rotatably accommodated in an opening 10 formed in the adjacent casing wall 2 so as to mount the body 5 for rocking or oscillating movement about the axes of the shafts 9.

Spanning the distance between the walls 2, and parallel to the walls 3 is a pair of spaced apart rails 2a. The rails straddle the body 5 and serve to limit the extent to which the body 5 may be rocked in either direction.

A contact carrier 11 is coupled to the body 5 for back and forth reciprocating movements in response to oscillation of the body. The carrier 11 comprises a generally U-shaped, conductive member having a web 12 terminating at each end in an upstanding flange 13 which is vertically slotted as at 14 for the pivotal accommodation of studs 15 carried by the body walls 8. Button contacts 16 are fixed to and project from the web 12.

The slots 14 are substantially greater in length than the diameter of the studs 15 so as to provide for limited lost motion between the body 5 and the carrier 11. The opposite ends of the carrier web 12 are deformed to form spring tongues 17 which bear against the studs 15 and constantly bias the carrier 11 downwardly, as viewed in FIG. 5.

Slideably accommodated in the body 5 is an indexing slide 18 of generally cup-shaped configuration having a bottom 19 and four upwardly diverging sidewalls 20. The slope of the walls 20 corresponds substantially to the slope of the two walls 7 of the body 5 so as to enable the slide 18 to nest in the body with the bottom 19 slideably supported on the center section 6. The rails 2a are so located as to lie in the path of sliding movement of the slide 18 and limit the extent to which the latter can move relatively to the body 5.

The upper end of each sidewall 20 terminates in a laterally extending flange 22 that slideably is accommodated in a groove 23 formed in the upper end of the adjacent wall 8. The upper end of each leg 8 has a flange 24 that overhangs the associated groove 23. Each end wall 21 of the slide member terminates in a projecting tongue 25, the upper surface 26 of which is inclined outwardly and downwardly of the slide member.

A pushbutton operator 27 is included and comprises a fingerpiece 28 provided at two of its opposite sides with depending legs 29 T-shaped in cross section and which are slideably accommodated in correspondingly shaped guide grooves 30 formed in the end walls 3 of the casing 1. Each end wall 3 has an inwardly extending enlargement 3a through which the associated leg 29 projects. The free end of each leg 29 terminates in an indexing or driving barb 31 which projects into the casing chamber 4. Each barb 31 has lateral extensions 31a which may abut the lower end of the adjacent enlargement 3a.

The operator 27 is reciprocable from a normal position indicated in full lines in FIG. 2 to a retraced position within the casing 1, as indicated in dotted lines in FIG. 2, and is biased toward its normal, projected position by a conical power spring 32, one end of which seats on a spring retainer 33 carried by the fingerpiece 28. The opposite end of the spring 32 has a rounded end 34 which is accommodated in a groove 35 formed in the bottom 19 of the index slide 18. Inward or retracting movement of the operator 27 is limited by abutments 36 on each wall 3 and lying in the path of movement of the legs 29.

The disclosed construction is especially adapted for use in conjunction with printed circuits and the like in which fixed, conductive strips 37 are supported on a suitable substrate or base 38. The casing 1, together with all of the parts contained therein, may be removably assembled with the base 38 by means of flexible, attaching lugs 39 which extend in prolongation of the casing end walls 3 and which may be accommodated in openings 40 formed in the base 38. The lugs 39 preferably have latching barbs 41 at their free ends for engagement with the under surface of the base 38, the lugs 39 being sufficiently flexible to enable the barbs to be disengaged and permit disassembly of the casing from the base. The length of the lugs 39 should be sufficient to pass through the base 38 and permit the contacts 16 on the carrier 11 to make engagement with the fixed contacts 37 in all positions of the carrier 11. The location and vertical height of the abutments 36 accomplishes this objective, together with the lost motion coupling of the carrier 11 to the body 5, in conjunction with the spring fingers 17.

When the casing 1 is in assembled relation with the base 38, as indicated in FIG. 2, the spring 32 will maintain the operator 27 in its projected position, the engagement of the barb extensions 31a with the enlargements 3a limiting outward movement of the operator. The spring 32 also exerts a force on the body 5 tending to rock it counterclockwise from the position shown in FIG. 2, but the engagement of the body 5 with the left-hand rail 2a prevents such rocking of the body. The carrier 11 thus is forcibly, but yieldably, maintained at one end of its path of movement. The force exerted by the spring 32 also urges the indexing slide 18 downwardly and toward the left from the position shown in FIG. 2 and in which the left-hand tongue 25 overhangs the associated end of the body 5. The engagement of the slide 18 with the left-hand rail 2a, however, precludes any movement of the slide 18 to the left from the position shown in FIG. 2.

Upon a retracting or inward stroke of the member 27, the legs 29 will move from the positions shown in full lines in FIG. 2 to the positions shown in dotted lines. The left-hand indexing barb 31 will engage the left-hand tongue 25 of the slide 18, the inclined surface 26 enabling the indexing barb 31 to cam or shift the slide 18 to the right, against the bias of the spring 32. When the barb 31 disengages the tongue 25, the spring 32 will return the slide to the left, whereupon the tongue 25 will overhang the barb 31. Upon release of the operator 27, the spring 32 will move the latter upwardly on its return stroke, whereupon the left-hand indexing barb 31 will engage the overhanging tongue 25 and rock the body 5 clockwise about the axis of the shafts 9. The indexing parts 25 and 31 will remain in engagement until the body has been rocked clockwise to a position in which it is inclined toward the opposite side of the casing, whereupon the spring 32 will rock the body to its other extreme position in engagement with the right-hand rail 2a, as shown in FIG. 3, and simultaneously shift the slide 18 to the right into engagement with the rail and locate the right-hand indexing tongue 25 in the path of movement of the right-hand indexing barb 31. Such movement of the slide 18 does not take place, however, until after the operator 27 has traversed a distance on its return stroke sufficient to enable the right-hand indexing barb 31 to be clear of the path of movement of the associated indexing tab 25.

As the actuator body rocks clockwise from the position shown in FIG. 2 to the position shown in FIG. 3, the carrier 11 will move from one end of the casing toward the other, whereupon the contacts 16 will engage different ones of the fixed contacts 37. During movement of the carrier the spring fingers 17 will deflect, as required, to enable the posts 15 to move longitudinally of the slots 14.

The carrier 11 may be returned to its initial position from the position shown in FIG. 3 upon the retraction of the operator 27 into the casing 1 a distance sufficient to locate the right-hand indexing barb 31 beneath the right-hand indexing tongue 25, whereupon the return stroke of the operator will rock the body 5 counterclockwise from the position shown in FIG. 3 to the position shown in FIG. 2. Thus, the operator 27 moves from and to its normal or projected position upon sequential strokes thereof, but the carrier 12 is shifted from one position to another on alternate strokes of the operator.

The disclosed embodiment is representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof.

Claims

I claim:

1. A switch construction comprising a casing; a body mounted in said casing for back and forth rocking movements about an axis between two extreme positions; contact carrier means coupled to said body for movements between first and second positions in response to back and forth rocking movement of said body; reciprocable operating means movable on sequential strokes from and to a normal position; first indexing means on said body; and second indexing means on said operating means and straddling said body, said first and second indexing means being operable in response to movement of said operating means to said normal position to rock said body from either extreme position to the other.

2. The construction set forth in claim 1, including spring means acting on said body for yieldably maintaining the latter in either of said extreme positions.

3. The construction set forth in claim 2 wherein said spring means acts on said operating means and biases the latter to said normal position.

4. The construction set forth in claim 1, wherein said first indexing means comprises a slide carried by said body and said second indexing means comprises a pair of arms carried by said operating means, each of said arms having drive means for engaging said slide and applying a force thereto sufficient to rock said body from one extreme position toward the other.

5. The construction set forth in claim 4 including spring means acting on said slide and urging it toward a position for engagement by a selected one of said drive means.

6. The construction set forth in claim 1, wherein said casing has an open side adjacent said carrier means.

7. The construction set forth in claim 6 including means carried by said casing for mounting the latter on a base with said open side and said carrier confronting said base.

8. A switch construction comprising contact carrier means movable along a path between first and second positions; actuating means rockable between two extreme positions; means coupling said actuating means to said carrier means for moving the latter from one of its positions to the other in response to rocking movement of said actuating means; reciprocable operating means straddling said actuating means and movable between first and second positions; and cooperable indexing means on said operating means and said actuating means engageable with each other in response to movement of said operating means from said first position to said second position, said indexing means being operable when engaged to rock said actuating means from one of its said positions to the other in response to movement of said operating means from said second position toward said first position.

9. The construction set forth in claim 8 including spring means biasing said operating means to said first position.

10. The construction set forth in claim 8 including spring means operable yieldably to maintain said actuating means in either of its said extreme positions.

11. The construction set forth in claim 8 including means for limiting movement of said actuating means beyond its extreme positions.

12. The construction set forth in claim 8 including spring means operable yieldably to maintain said carrier means in either of its said positions.

13. The construction set forth in claim 8 wherein said indexing means comprises a slide member slideably supported by said actuating means for sliding movements relative thereto.

14. The construction set forth in claim 13 including spring means acting on said slide member and yieldably maintaining the latter in a selected position relative to said actuating means.

15. The construction set forth in claim 14 wherein said spring means is operable to shift said slide member from said selected position to another position in response to movement of said actuating means from one of its said positions to the other.

16. The construction set forth in claim 15 wherein said slide member projects beyond one side of said actuating means in one extreme position of said actuating means and projects beyond the opposite side of said actuating means in the other extreme position thereof.

17. The construction set forth in claim 8 wherein said coupling means includes a lost motion connection between said actuating means and said carrier means.

18. The construction set forth in claim 8 including a casing in which said carrier means is mounted, said casing having an open side adjacent said carrier means; and means for mounting said casing on a support having conductive means confronting said carrier means through said open side.

19. The construction set forth in claim 18 wherein said mounting means comprises flexible extensions of said casing terminating in barbed ends accommodated in openings in said support.