US3711667A

US3711667A - Spring loaded pushbutton switch

Info

Publication number: US3711667A
Application number: US00147818A
Authority: US
Inventors: G Farrell
Original assignee: Chicago Switch Inc
Current assignee: Chicago Switch Inc
Priority date: 1971-05-28
Filing date: 1971-05-28
Publication date: 1973-01-16
Anticipated expiration: 1990-01-16

Abstract

A switch including opposed, spaced apart contacts, and a movable contact mounted in a carrier. The movable contact may comprise a transversely extending pin adapted to bridge the spaced apart contacts when the carrier is moved into one position. A spring is disposed within the carrier for normally biasing the movable contact in the direction of the spaced apart contacts whereby engagement of the movable contact with the spaced apart contacts will impart a force to the movable contact in opposition to the force of the resilient means. A pair of pins may be employed to provide redundancy, and pins may be located at opposite ends of the carrier with a separate set of spaced apart contacts being bridged by one or more separate pins.

Description

[ 1 Jan. 16, 1973 United States Patent [191 Farrell Primary Examiner-Robert K. Schaefer Assistant Examiner-M. Ginsburg I Attorne.y-McDougall, Hersh & Scott 60606 [73] Assignee: Chicago Switch Inc.,

[57] ABSTRACT A switch including opposed, spaced apart contacts,

and a movable contact mounted in a carrier. The

movable contact may comprise a transversely extending pin adapted to bridge the spaced apart contacts when the carrier is moved into one position. A spring is disposed within the carrier for normally biasing the [52] U.S. Cl. R [51] Int. 3/12 of Search R, A 159 B, 5 R movable contact 1!] the dIrectIon 0f the spaced apart 200/5 A 5 B, 5 C, 5 D. 5 E 5 EA, 5 EB 5 F, contacts whereby engagement of the movable contact 169 P3 with the spaced apart contacts will impart a force to the movable contact in opposition to the force of the resilient means. A pair of pins may be employed to provide redundancy, and pins may be located at opposite ends of the carrier with a separate set of spaced apart contacts being bridged by one or more separate pins.

2,363,854 Bierenfeld ......................200/l69 PB 1,744 626 1/1930 Getchell ...........................200/159 R FOREIGN PATENTS 0R APPLICATIONS 12 Claims 12 Figures 5/1968 Germany...I....................,.200/159R PATENTEUJAH 16 I975 SHEET 2 BF 2 FIG, 5 F1619 FIGJO FIG. 1 1

SPRING LOADED PUSIIBUTTON SWITCH This invention relates to an improved switch construction employing resilient means for engaging contacts in the switch. The invention is particularly concerned with a switch construction having greatly improved operating characteristics, particularly from the standpoint of bounce" characteristics.

Many circuit applications require switches which require movement of switch contacts into engagement at high relative speeds. For example, an operator may engage a push button which will move one set of contacts rapidly into engagement with another set of contacts and, of course, a degree of energy will be involved in this movement proportional to the speed and force of application.

The energy must be dissipated in some fashion, and in many switches, the dissipation involves bounce of the contacts. For example, where a movable contact is driven against a stationary contact, the movable contact will often bounce back or disengage momentarily because of the reaction force. This can create significant problems in sensitive circuits since the momentary disengagement of the contacts will provide a break which could lead to a false signal. For example, a signal could be transmitted upon initial engagement of the contacts, and then a second signal transmitted subsequent to the bounce.

It is a general object of this invention to provide an improved switch construction which overcomes problems which particularly occur with switches employed in sensitive electrical circuits.

It is a more particular object of this invention to provide a switch construction which is characterized by freedom from bounce to the extent that no apparent effect on circuit operation will occur even in highly sensitive circuitry.

These and other objects of this invention will appear hereinafter, and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is an elevational view of the switch construction of this invention, partly in section, and taken about the line I-l of FIG. 3;

FIG. 2 is an elevational view of the switch construction illustrating the contact carrier in the depressed position;

FIG. 3 is a vertical sectional view of the switch construction taken about the line 33 of FIG. 1;

FIG. 4 is an elevational view, partly in section, taken about the line 4-4 of FIG. 3;

FIGS. 5, 6 and 7 are horizontal sectional views taken about the lines 55, 6-6 and 77, respectively, of FIG. 1;

FIG. 8 is an exploded perspective view of the switch construction shown in FIG. 1;

FIG. 9 is an elevational view, partly cut away, illustrating a modified form ofthe invention;

FIG. 10 is an exploded elevational view of the switch construction shown in FIG. 9;

FIG. 11 is an enlarged plan view of the switch housing taken about the line 11-11 of FIG. 10; and,

FIG. 12 is a bottom plan view of the switch housing taken about the line I2-l2 of FIG. 10.

This invention generally concerns a switch construction which includes opposed spaced apart contacts mounted within a housing. A movable contact is located on a carrier, and means are provided for displacing the carrier within the housing to thereby move the movable contact into and out of bridging relation with the spaced apart contacts. The movable contact is held within the carrier by means of a spring or other resilient means which biases the movable contact in the direction of the spaced apart contacts.

In the switch operation, the carrier moves the movable contact toward and away from the spaced apart contacts. When engaging the spaced apart contacts, the resilient means mounted within the carrier immediately resists any tendency of the movable contact to bounce away from the spaced apart contacts. The design of the switch construction is such-that this operation can be achieved in a highly efficient manner from a part cost and assembly standpoint whereby the switches can be economically produced for use in large numbers, particularly in circuits which benefit from the elimination of apparent bounce.

The embodiment of the invention shown in FIGS. 1 through 8 comprises a switch I0 including a housing 12. The housing includes a bottom recess 14, and a plurality of terminals 16 are exposed within this recess whereby the switch can be included in a circuit. The terminal 16 may be of the type requiring attachment of leads or may be suitable for insertion in a printed circuit board.

In the embodiment shown, the terminals 16 comprise extensions of sheet members which are located within the housing 12. A first sheet member 18 defines an exposed upper edge 20 and a second sheet member 22 defines an exposed edge 24 located in the same plane as the edge 20. A third sheet member 26 defines an exposed lower edge 28. A fourth exposed edge 32 is defined by the sheet member 22. Thus, as best shown in FIG. 8, the sheet member 22 defines a pair of terminals 16 while the

sheet members

18 and 26 are separate from each other and define individual terminals. As best shown in FIGS. 5, 6 and 7, these sheet members are located within passages defined by the interior walls of the housing whereby the respective sheet members are insulated from each other. T-

shaped portions

34 and 36 form passages at the bottom of the construction for confining the lower ends of the four members. The four rails 38 maintain the separation throughout the length of the housing.

The rails 38 also define grooves 40 which serve as guides for the side edges 42 of plate 44. The plate 44 includes an upper portion 46 extending outwardly of the housing 12, and a button 48 is secured on this extension. As will appear, the combination of the plate 44 and button 48 serve as a plunger mechanism for operating the switch.

The plate 44 defines a central opening 50 (FIG. 8) for receiving a carrier 52. This carrier defines a lower groove 54 adapted to engage the lower edge 56 of the opening 50. The combination of the groove 54 and upper tabs 58 provide a means for locating the carrier 52 on the plunger during the assembly operation.

The carrier defines a central bore 60 and slots 62 defined in its side walls. Contact pins 64 are inserted within the slots with the spring 66 being disposed between the contact pins. This arrangement resiliently holds the contact pins against the ends of the slots 62.

The pins 64 extend outwardly beyond the sides of the carrier whereby these pins are adapted to bridge the contacts provided by the aforementioned sheet members. In the example illustrated, the upper set of pins forms a bridge between the

edges

28 and 32 while the lower set forms a bridge between the

edges

20 and 24, the bridging condition depending upon the position of the switch.

The switch position is controlled by means of a spring 68 which is seated against the closed bottom 70 of the housing 12. The upper end of the spring is positioned around central arm 72 defined by the plate 44. With this arrangement, the switch is normally held in the position shown in FIGS. 1 and 3. Upon depression of the plunger, the position shown in FIG. 2 will be achieved.

In the operation of the switch construction, the depression of the plunger will result in breaking of the bridging contact between the upper set of pins 64 and the

contact edges

28 and 32. Continued depression will then serve to make bridging contact between the lower set of pins 64 and the

contact edges

20 and 24.

This break before make" arrangement is not required, however, since the structure can be easily designed to provide making of the lower set of contacts before breaking of the upper set, for example, by locating the sets of contact edges closer together, or by increasing the size of the carrier to provide longer slots. The switch can also be designed to provide a normally open condition wherein the carrier will hold the pins at some intermediate location. Similarly, an all contacts closed condition can be achieved without difficulty, and in this case, depression of the plunger will break one side while retracting of the plunger will break the other side.

The use of sheet members of the type shown which provide the contact edges also leads to a great deal of the versatility. For example, the sheet member 22 could be divided to thereby change the switching characteristics. It is also possible to design sheet members which are separated so that they will be engaged by only one pin whereby the redundant features which characterize the illustrated switch will be eliminated. It is preferred, however, to provide the redundant arrangement in order to decrease the possibility of losing contact because of contamination.

Irrespective of the particular design employed, the low bounce characteristics of the switch are achieved. This is accomplished due to the fact that the spring 66 mounted within the carrier 52 will immediately resist any tendency of the pins 64 to disengage from the contact edges. In this connection, the redundancy is also of value since, even if there is a slight bounce in both pins, chances are the bounces will not be in phase, and, therefore, contact will not be interrupted. It will be appreciated that in referring to the elimination of bounce, apparent bounce only is being considered. Thus, problems in very sensitive circuits are eliminated as long as the circuit interruption due to bounce is so short that even sensitive circuits will not detect the interruption. The switch structure described is highly effective for eliminating any detectable or apparent bounce.

FIGS. 9 through 12 illustrate one alternative design possible in accordance with the teachings of this invention. In this embodiment, the switch includes a housing 82 and a cover 84. This cover includes downwardly extending tabs 86 adapted to snap over shoulders defined by the housing 82. A central opening for receiving the upper end 88 of plunger. 90 is defined by this cover.

The housing 82 defines a closed bottom 92, and spring 94 seats on this bottom. A central arm 96 defined by the plunger 90 receives the upper end of this spring whereby the plunger is normally maintained in the upper position and is adapted to be depressed through engagement of the extension 88.

A carrier 98 'of the type previously described is located within a central opening defined by the plunger. A compression spring 100 located within the body of the carrier presses downwardly on the contact pins 102. These pins are located within slots 104 and extend outwardly on either side of the carrier in the manner previously described.

A pair of contacts 106 are located within the housing 82. These contacts define edges 108 which are located in spaced relationship and which are adapted to be bridged by the pins 102. The terminals 110 of the switch comprise integral extensions of the sheet members 106. As best shown in FIG. 9, shoulders 112 are defined by the interior walls of the housing82, and these shoulders engage the lower edge portions 114 of the contacts 106 for purposes of accurately locating the contacts within the housing.

In the operation of the switch 80, the plunger 90 is normally in the raised position whereby the pins 102 are out of contact with the stationary contact'edges 108. Upon depression of the plunger, the pins-102 move into engagement with these edges. In the absence of latching means which could be employed for holding the plunger in a depressed condition, release of the plunger will result in breaking of the contacts.

The structure shown in FIGS. 9 through 12 is a relatively simple switch design which includes the low bounce characteristics but which can be manufactured at a very low cost. This is a highly important factor in that switches of this type must often be employed in very large numbers whereby any savings achieved in an individual switch will be multiplied many times.

It will be understood that various changes and modifications may be made in the above described construction which provide the characteristics of this construction without departing from the spirit thereof particularly as defined in the following claims.

That which is claimed is:

1. In a switch construction comprising opposed, spaced apart contacts, a movable contact, a carrier for said movable contact, said carrier being adapted to be located in a first position whereat said movable contact is spaced from said spaced apart contacts and in a second position whereat said movable contact bridges said spaced apart contacts, means for displacing said carrier to move the carrier between said first and second positions, resilient means associated with said carrier and bearing against said movable contact to bias said movable contact toward said spaced apart contacts, and a housing receiving said carrier, and said movable and spaced apart contacts, the improvement wherein said movable contact comprises at least one pin extending transversely relative to said carrier with the ends of the pin being exposed outwardly of the carrier for engagement with said spaced apart contacts, and wherein said spaced apart contacts comprise thin sheet members having edges extending along a line perpendicular to the axis of said pin, the ends of said pin contacting said edges, and passages defined by the interior walls of said housing for receiving said sheet members and holding the sheet members spaced apart.

2. A construction in accordance with claim 1 including terminals extending outwardly for including the construction in a circuit, said terminals comprising an integral portion of said sheet members.

3. A construction in accordance with claim 2 including a second set of spaced apart contacts positioned on the opposite side of said carrier relative to said first mentioned spaced apart contacts.

4. A construction in accordance with claim 3 including a second movable contact mounted in said carrier in spaced relationship with said first movable contact, said resilient means bearing against said second movable contact to thereby bias said second movable contact toward said second set of spaced apart contacts.

5. A construction in accordance with claim 3 including a second set of terminals extending outwardly for including said second spaced apart contacts in an electrical circuit, said second spaced apart contacts comprising sheet members defining exposed edges for engagement with a movable contact, and said terminals comprising integral portions of said sheet members.

6. A construction in accordance with claim 1 wherein said means for displacing said carrier comprising a plate member movable within said housing, said plate member defining an opening receiving said carrier and securing the carrier to the plate member.

7. A construction in accordance with claim 6 wherein said housing defines a closed bottom and a compression spring extending between said bottom and said plate member for normally holding said carrier in one of said positions.

8. A construction in accordance with claim 7 including grooved areas defined in the walls of said housing, the edges of said plate member being received in said grooved areas for guiding said plate member.

9. A construction in accordance with claim 6 wherein said plate member includes an extension disposed outwardly of said housing, and means engaging said extension for imparting movement to said plate member.

10. A switch construction comprising first and second pairs of opposed, spaced apart contacts, movable contacts, a carrier for said movable contacts, means whereby said carrier is adapted to be located in at least first and second positions, said movable contacts comprising pins and resilient means within said carrier for holding said pins in spaced relationship with each other, at least one of said pins bridging the first pair of spaced contacts in the first position of said carrier and at least one other pin bridging the second pair of spaced contacts in the second position of said carrier, said resilient means biasing the respective bridging pins against the bridged spaced contacts whereby engagement of a pin with spaced apart contacts imparts a force to said pin in opposition to the force of said resilient means.

. A construction in accordance with claim 10 wherein said resilient means comprises a compression spring mounted within said carrier.

12. A construction in accordance with claim 10 wherein each of said movable contacts comprises a pair of pins held apart by said resilient means to provide redundant contact with said spaced apart contacts.

Claims

11. A construction in accordance with claim 10 wherein said resilient means comprises a compression spring mounted within said carrier.