US3311717A

US3311717A - Electrical switch with improved movable contact and detent structure

Info

Publication number: US3311717A
Application number: US514247A
Authority: US
Inventors: Melvin A Lace
Original assignee: Oak Electro Netics Corp
Current assignee: Oak Electro Netics Corp
Priority date: 1965-12-16
Filing date: 1965-12-16
Publication date: 1967-03-28
Anticipated expiration: 1984-03-28
Also published as: NL6617610A; GB1127689A; DE1665294A1; DE1665294B2; FR1505074A

Description

March 28, 1967 M. A. LACE ELECTRICAL SWITCH WITH IMPROVED MOVABLE CONTA AND DETENT STRUCTURE 4 Sheets-Sheet 1 Filed Dec. 16, 1965 INVENTOR mfid/ ATTORNEYS March 28, 1967 M A LACE 3,311,717

ELECTRICAL SWITCH WiTBdMPROVED MOVABLE CONTACT AND DETENT STRUCTURE Filed Dec. 16, 1965 4 Sheets-Sheet 2 March 28, 1967 ELECTRICAL SWITCH WJETH IMPROVED MOVABLE CONTACT AND DETENT STRUCTURE Filed Dec. 16, 1965 M A. LACE 4 Sheets-Sheet 3 64 60 4 v r 60 58 I I I 5 l fii yj 6/ 62% g i I 1 37 March 28, 1967 M. A. LACE 3,311,717

ELECTRICAL SWITCH WITH IMPROVED MOVABLE CONTACT AND DETENT STRUCTURE 7 Filed Dec. 16, 1965 4 Sheets-Sheet 4 United States Patent ELECTRICAL SWITCH WITH IMPROVED MOVABLE CONTACT AND DETENT STRUCTURE Melvin A. Lace, Prospect Heights, [1]., assignor to Oak Electro/Netics Corp., a corporation of Delaware Filed Dec. 16, 1965, Ser. No. 514,247 13 Claims. (Cl. 200-8) This invention relates to an electrical switch, and more particularly to an electrical switch capable of being constructed in a miniature size.

Conventional switch constructions are impractical for electrical switches of greatly reduced size. Individual components forming the switch, which are easily manufactured for switches of conventional size, are difficult to manufacture economically in miniature. The large number of components used in conventional switch designs make assembly diflicult, and increase the possibility of failure and poor electrical contact between switching terminals. It is also difficult to provide a strong detent action, desirable for many applications, in a miniature switch.

In accordance with the present invention, a greatly simplified design for an electrical switch is presented. This design allows a switch to be constructed in a miniature size, while providing good electrical contact and positive detent action when desired. Furthermore, a variety of switching arrangements are possible.

One object of this invention is to provide an electrical switch of improved and greatly simplified design.

Another object of. this invention is to provide an electrical switch capable of being constructed in a miniature size.

One feature of this invention is the provision of an electrical switch using an electrically conductive ball as the bridging element between electrical contacts.

Another feature of this invention is the provision of an electrical switch using a plurality of elongated, electrically conductive members, as wires, for forming electrical switching contacts.

Still another feature of this'invention is the provision of an electrical switch occupying a minimum of space, and having a minimum number of components.

A further feature of this invention is the provision of an electrical switch using resilient wires for electrical contacts, and a movable electrically conductive ball for forming a bridging electrical path between the contacts.

Further objects and features of the invention will be apparent from the following specification and from the drawings, in which:

FIG. 1 is a perspective view of one embodiment of the invention;

FIG. 2 is an exploded view of the switch of FIG. 1;

FIG. 3 is a side view, partly in section, of the switch of FIG. 1;

FIG. 4 is a top view, partly in section, of the switch of FIG. 1;

FIG. 5 is a view similar to FIG. 4 of a switch with a modified switching contact construction; FIG. 6 is a side view, partly 'in section, of another modification of the switch of FIG. 1;

FIG. 7 is a diagrammatic plan view of another embodiment of switch contacts;

FIG. 8 is an exploded view of a switch embodying the contacts of FIG. 7;

FIG. 9 is a top view, partly in section, of the switch of FIG. 8;

FIG. 10 is a top view, partly in section, of another embodiment of the electrical switch;

FIG. 11 is a side view, partly in section, of the switch of FIG. 10,

"ice

FIG. 12 is a top view similar to FIG. 5 of a switch with a modified detent construction; and

FIG. 13 is a side view, partly in section, of a sealed switch construction.

While illustrative embodiments of the invention are shown in the drawings and will be described in detail herein, the invention is susceptible of embodiment in many different forms and it should be understood that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

In FIGS. 1-4, one embodiment of the invention in a rotary electrical switch is illustrated. A plurality of electrically conductive wires 20, extending above a support 21, form the electrical contacts of the switch. End portions 22 of wires 20 extend below base 21 and form terminals for connection to an external electrical circuit (not illustrated). A ball 24 of electrically conductive material is wedged in the space between adjacent wires 20 and a central ball contact wire 25. A sliding member (not illustrated), composed of electrically conductive material, could be used in place of the rolling ball 24.

Wires 20 are arranged in the shape of a ring, concentric with wire 25. A bridging electrical path between adjacent wires 20 is formed through the ball 24. A ball carrier 26 is used to move ball 24 around the ring and into engagement with different electrical contacts.

Carrier 26 is a cylindrical body of insulating material, having a generally U-shaped recess 28 therein. Recess 28 is defined by a pair of side walls 29 and a back wall 30, seen best in FIG. 4. The width of recess 28 is slight ly greater than the diameter of ball 24, and the surfaces of walls 29 abut the ball. A screwdriver slot 32 on carrier 26 allows the carrier to be rotated concentric with wire 25, moving ball 24 into engagement with adjacent pairs of wires 20. Resilient wire 25 is used both as an electrical contact terminal and as a spring for holding ball 24 in contact with the ring of wires 20. This switch provides a bridging action between the center wire 25 and any two adjacent wires 20. Of course, it is not necessary toause wire 25 as an electrical terminal, as the ring of elongated electrical contacts 20 may be used by themselves in certain types of switching arrangements.

To distribute the stress in wire 25, and hence" increase the life of the switch, a central portion 33 of base 21 can be relieved, as seen in FIG. 3, exposing a greater length of wire 25. Recess 33 may be filled with a material that is more resilient than the material forming base i 21 in order to distribute the stress on the wire 25 where it enters base 21. Similarly, wire 25 may be tapered in order to distribute the stress and provide a longer lasting switch.

As seen in FIGS. 1 and 3, the upper ends of wires 20 extend over the top of carrier 26, forming a rotatable mounting for the ball carrier. The lower portions 22 of Wires 20 may be directly inserted into a printed circuit board and soldered thereto.

The switch construction described above, using a minimal number of easily formed components, can be economically manufactured in a miniature size. For example, the switch illustrated in FIGS. 1-4 was constructed.

using 0.015 inch diameter gold plated music wire, and a 0.046 inch diameter ball. The switch is not to be limited to a miniature size, however, since the simple and extremely compact design can be used in switches of any desired size.

In FIG. 5, a modified switch incorporating a positive detent mechanism, is illustrated. In place of electrical contacts 20, an outer ring of electrical contact wires or pins 36 is provided, A second smaller ring of detent wires 37 extends outward from base 21 concentric with the ring of wires. Pins 37 are spaced equidistant from adjacent pins 36, and need not be of electrically conductive material. Similarly, since detent wires 37 are not used as electrical contacts, ball carrier 26 can be formed from an electrically conductive material. With the construction illustrated, five pairs of switching contacts are provided, each using a single pin 36, with wire 25 as the common electrical contact terminal.

Wires 37 form a positive detent mechanism for ball 24. The detent action can be made heavier by using wires 37 of larger diameter or stiffer construction than the

other wires

36 and 25. The spacing of the detent wires can also be varied to change the detent action. As ball 24 is moved out of engagement with a particular pin 36 by rotation of the carrier 26,

wires

25 and 37 give, allowing ball 24 to pass through and snap into the next detent position.

In order to increase the number of switching contacts,

a greater number of equally spaced wires maybe placed ina ring around common wire 25. As the number of contacts is substantially increased, the diameter of the ring must be increased, and hence also the diameter of ball 24.

The switch construction illustrated in FIG. 6 allows the number of contacts to be increased without increasing the size of ball 24. An electrically conductive cap 39, carried by central wire 25, has an arcuate peripheral surt ace 40 which abuts ball 24. The ball rests on an O- shaped washer 41 which is raised from base 21 by fingers 42. Ball carrier 26 is rotatably mounted between an upper support 44, formed from insulating material, and

base 21. The conductive cap for wire 25 can be used with either of the embodiments illustrated in FIGS. 4 or 5.

For some applications, a separate electrical contact for each pin 36 is desired. The switch contact arrange.- rnent illustrated in FIG. 7 provides an unlimited number of pairs of contacts. Pins 36 form one contact for each of the pairs of contacts. The other contact is formed trom a pin or wire 46 spaced radially inward from and opposite each wire 36. Wires 46 are arranged in a ring of smaller diameter than either of the rings of

wires

36 or 37. In FIG. 7, each pair of switching contacts 36-46 is indicated by the same number of primes. Ball 24 is located in the space between the rings of

wires

36, 37 and wires 46.

The ball when at rest is detented in either an outer position, between adjacent detent wires 37 and

wires

36, 46, e.g. position 48 in FIG. 7, or an inner position, e.g. position 49, between one detent wire 37 and adjacent wires 46. As ball 24 is moved counterclockwise, for example from position 48 in FIG. 7, it snaps into an inner detented position between

ball contacts

37, 46 and 46. As ball 24 is again urged counterclockwise, it moves into the outer position 48' illustrated in FIG. 7. The path of ball 24 is thus seen to follow a zigzag pattern around a circle concentric with the rings of ball contacts.

Ball 24 is more positively detented in the outer position than in the inner position, due to the larger distance between adjacent wires in the outer rings. The detent action may be made equal by using smaller diameter (or stifler) wires 46 for the inner ring. Alternatively, an electrically insulated ball can be placed on the opposite side of the ball path, detenting in an outer position when ball 24 detents in an inner position.

In FIGS. 8 and 9, a switch embodying the ball contact arrangement of FIG. 7 is illustrated. In this embodirnnt, an electrically insulated spacer 50 is inserted in the center of the ring of contacts 46. Spacer 50 has webs 51 which protrude into the space between adjacent electrical contacts 46 to prevent ball 24 from detenting in the inner position and bridging adjacent electrical con- 4 tacts 46, Thus, the pairs of separate switching contacts are completely independent from each other. i

The ball carrier is formed in the shape of a hollow cylindrical shell 54, located in the space between contacts 46 and

contacts

36, 37. A nylon ball 55 is located opposite ball 24 for balancing the detent action. Of course, ball 55 or other additional balls (not illustrated) may be made conductive to provide additional bridging contacts for the switch. i

The switch of FIGS. 8 and 9 can be modified as illustrated in FIGS. 10 and 11 to provide a single common terminal 57 in place of individual independent terminals 46. Electrically conductive common terminal 57 is resiliently mounted to base 21 by spring wires 58, for biasing ball 24 into firm engagement with contacts 36. A top portion of wires 58 protrudes through base 21 for connection with an external electrical circuit.

Common terminal 57, which may be formed from brass, has a hollow configuration in order to reduce its mass. This produces a light weight cylinder having a generally U-shape defined by an outer side wall 60, a bottom wall 61, and an inner side wall 62. Spring wires 58 are imbedded in the bottom wall 61. shell 54 is rotated by an attached shaft 64 which protrudes through the central openings in cylinder 57 and base 21. Base 21 further has an annular downwardly extending outer wall 65 which protrudes below the level of the switch mechanism. A cover 66 is secured to wall 65 to enclose the switch mechanism.

It is not necessary that ball 24 abut detent wires 37 to lock the mechanism against accidental rotation. In FIG. 12, a modification of the switch of FIG. 5 is illustrated in which the wires 37 detent on a corner of the ball carrier 26, instead of on the ball 24 itself. The outer periphery of ball carrier 26 has shallow, slightly recessed portions 70 which abut detent wires 37 and hold the ball carrier in place. The remaining outer surface periphery 71 of carrier 26 has a slightly larger diameter than the diameter of ball carrier 26 in FIG. 5, in order to snap the ball carrier into the detented position illustrated in FIG. 12,

Since ball 24 is of necessity smaller than ball 24 of FIG. 5 when the

contacts

36, 37 are of identical dimen: sions, the effective diameter .of central contact wire 72 must be proportionately increased. This may be accomplished by using a wire 72 of larger diameter than

wires

36 or 37, or by securing an electrically conductive cap, similar to cap 39 in FIG. 6, to the central wire 72. V

The various switches shown herein may be sealed by the constructionillustrated in FIG. 13. The switch itself is similar to that illustrated for FIG. 3, with the exception that the top portions of wires 20 are not turned over the top of ball carrier 26.

The switch is encased in a hollow cylindrical shell 75 of insulating material. A circular opening in the top of shell 75 allows the screwdriver adjustment 32 to protrude therethrough. An 0 ring 76, wedged between rotatable ball carrier 26 and shell 75, forms a seal between the opening in the shell and the switch mechanism. An outer steel shell 78 forms a protective covering for inner shell 75. The steel shell 78 is bonded to the plastic shell 75 by a layer 79 of synthetic resin such as silicone rubber. With this construction, the switch mechanism is protected against impact as well as moisture and atmospheric conditions. Any of the switch mechanisms illutrated in FIGS. 1-12 may be encased in the manner illustrated in FIG. 13.

It should be noted that the electrical switches described may be easily ganged together as by using gears, or in some cases hollow concentric shafts I claim:

1. An electrical switch comprising:

a support,

a plurality of elongated, electrically conductive contact Ball carrier' members extending from said support and arranged substantially equally spaced from each other in the shape of a ring,

a bridging contact of conductive material movable across said support tocomplete a circuit between contact members,

a resilient wire extending from said support and located at the center of said ring, 7 7

said bridging contact being located between said resilient wire and adjacent conductive contact members along said ring,

a carrier adjacent said bridging contact for moving said bridging contact along said ring, and

means mounting said carrier for rotation about the center of said ring.

2. The switch of claim 1 wherein the upper ends of a portion of said elongated, electrically conductive contact members extend over a top portion of said carrier, thereby forming said mounting means.

3. An electrical switch, comprising:

an insulated support;

a plurality of electrically conductive wires extending from said support and arranged substantially equally spaced from each other in the shape of a first ring;

electrically conductive contact means mounted on said support, defining a circle of different diameter than the diameter of said first ring and concentric therewith;

an electrically conductive member located between said first ring and said circle, the engagement of said member with one of said wires and said contact means forming a conductive path therebetween through said member;

a plurality of spaced detent wires for contacting and holding said member in engagement with only one conductive wire, said detent wires being mounted on said support and arranged the shape of a second ring with each detent wire being located between adjacent conductive wires;

and carrier means for moving said member.

4-. The switch of claim 3 wherein a portion of said carrier abuts said detent wires and is held thereby, said carrier holding said member in engagement with only one conductive wire.

5. The switch of claim 3 wherein said contact means comprises a single resilient wire located in the center of said first ring, forming a common electrical contact for each of said conductive wires.

6. The switch of claim 3 wherein said contact means comprises a cylindrical body having a conductive outer surface, said mass being resiliently mounted to said support, forming a common electrical contact for each of said conductive wires.

6 7. The switch of claim 3 wherein said contact means comprises a second plurality of electrically conductive wires spaced along said circle, each of said second wires forming an individual electrical contact for a corresponding conductive wire along said first ring.

8. The switch of claim 7 wherein said second plurality of wires is of smaller diameter than the wires of said first ring.

9. The switch of claim 7 including electrical insulating means attached to said support and located between said second wires for preventing said member from bridging adjacent second wires, each of said second wires there by forming an independent electrical contact for a corresponding conductive wire along said first ring.

10. An electrical switch comprising:

a support;

a plurality of elongated electrically conductive contact members extending from said support and arranged substantially equally spaced from each other in the shape of a ring;

a resilient electrically conductive contact wire extending from said support;

a ball of conductive material inside said ring, physically contacting at least one of said members in said ring and contacting and flexing said resilient wire, the fiexure of said wire creating a spring action force urging said ball toward said member;

a carrier adjacent said ball for moving said ball along said ring; and

means mounting said carrier for rotation about said ring.

11. The switch of claim 10 including means for reducing the'spring action stress along the portion of said resilient wire which extends above the plane of said support.

12. The switch of claim 11 wherein said stress reducing means comprises a recess formed in said support around said resilient wire below the plane of said support, exposing a length of resilient wire.

13. The switch of claim 3 wherein said second ring has a diameter intermediate that of said first ring and said circle.

References Cited by the Examiner UNITED STATES PATENTS 7 3,052,763 9/1962 Nathe 2008 3,197,579 7/1965 Romney 2008 X 3,214,528 10/1965 Seabury et a1 2008 X 3,226,496 12/1965 Seabury et a1. 2008 X ROBERT K. SCHAEFER, Primary Examiner. I. R. SCOTT Assistant Examiner.

Claims

1. AN ELECTRICAL SWITCH COMPRISING: A SUPPORT, A PLURALITY OF ELONGATED, ELECTRICALLY CONDUCTIVE CONTACT MEMBERS EXTENDING FROM SAID SUPPORT AND ARRANGED SUBSTANTIALLY EQUALLY SPACED FROM EACH OTHER IN THE SHAPE OF A RING, A BRIDGING CONTACT OF CONDUCTIVE MATERIAL MOVABLE ACROSS SAID SUPPORT TO COMPLETE A CIRCUIT BETWEEN CONTACT MEMBERS, A RESILIENT WIRE EXTENDING FROM SAID SUPPORT AND LOCATED AT THE CENTER OF SAID RING, SAID BRIDGING CONTACT BEING LOCATED BETWEEN SAID RESILIENT WIRE AND ADJACENT CONDUCTIVE CONTACT MEMBERS ALONG SAID RING, A CARRIER ADJACENT SAID BRIDGING CONTACT FOR MOVING SAID BRIDGING CONTACT ALONG SAID RING, AND MEANS MOUNTING SAID CARRIER FOR ROTATION ABOUT THE CENTER OF SAID RING.