US3371167A - Miniature rotary switch with contoured contacts - Google Patents

Description

Feb. 27, 1968 G. SOULAKIS, JR 3,371,167

MINIATURE ROTARY SWITCH WITH CONTOURED CONTACTS Filed Dec. 13, 1965 United States Patent 3,371,167 MINIATURE ROTARY SWITCH WITH CONTOURED CONTACTS George Soulakis, Jr., Pasadena, Calif., assignor to Spectrol Electronics Corporation, City of Industry, Calif., a corporation of Delaware Filed Dec. 13, 1965, Ser. No. 513,203 4 Claims. (Cl. 200-11) ABSTRACT OF THE DISCLOSURE Disclosed is a miniature rotary switch having a plurality of discrete positions contactable by a movable contact member connected to a rotor or drive mechanism. The discrete positions are each constituted by a conduit surface extending upwardly into a cavity defined by the housing of the switch and the movable contact is defined by an arm having a contact surface which mates with the conduit surface of the stationary contacts and also includes a pair of cam surfaces extending from the contact surface but which are adapted to engage the conduit surface of the stationary contacts as the contact arm is moved, thereby to wipe against the clean c onduit surfaces of the stationary contact elements. The switch is sealed from the atmosphere by a rubberlike resiliently deformable washer member internally of a portion of the housing which mates against and seals with the rotor and the base of the housing.

This invention relates generally to switches and more particularly to a miniature rotary switch adapted for microcircuitry applications.

Switching devices adapted for use in the microcircuit field have been continuously reduced to smaller and smaller sizes in order to be compatible with the remainder of the circuit elements presently found in such applications. It has been found, however that as the switches grow smaller and smaller the reliability thereof; particularly under stress operation, decreases. Furthermore, the contact areas thereof also decrease. As the contact areas decrease, contact resistance thereof increases and as a result operating disadvantages and problems occur. The increased contact resistance experienced in the prior art switches appreciably raises the minimum amount of current which the switching devices will pass and as a result thereof greatly reduces the usability of the switching device in the microcircuit field for which it was designed originally.

Accordingly it is an object of the present invention to provide a miniature rotary selector switch having multiple positions each with the capability of passing a very low minimum current and which switch is extremely simple in configuration, is rugged in construction, and is extremely reliable in operation.

It is another object of the present invention to provide a miniature selector rotary switch having relatively large contact areas as compared to prior art switches of similar exterior dimensions.

It is another object of the present invention to provide a miniature rotary selector switch having high unit contact pressures to provide reliable contact which can be maintained even under adverse operating conditions.

It is another object of the present invention to provide a miniature rotary selector switch which is extremely small which has a plurality of contact points, and yet which is sealed to preclude the entry of foreign contarninants and moisture.

Additional objects and advantages of the present invention will become apparent from a consideration of the following description taken in conjunction with the accompanying drawing which is presented by way of example only and is not intended as a limit upon the scope of the claims appended hereto and in which:

FIG. 1 is a perspective view partially cut away of a miniature rotary selector switch in accordance with the present invention;

FIG. 2 is a cross-sectional view taken about the lines 22 of FIG. 1;

FIG. 3 is a top view partially in cross-section taken about the lines 3-3 of FIG. 2;

FIG. 4 is a view partly in cross-section taken about the lines 4-4 of FIG. 3 and illustrating the relationship of the movable and stationary contacts of a switch in accordance with the present invention.

A miniature rotary selector switch is accordance with the present invention includes a housing which defines a cavity. Disposed within the cavity is a plurality of stationary contact elements which are contacted by a rotary contact element which is rotatably supported within the cavity. Drive means extend through the housing and engage the rotary contact element in such a manner that upon actuation thereof rotary motion is imparted to the contact element to cause it to sequentially contact the stationary contact elements.

Referring now to the drawing and more particularly to FIG. 1 thereof, a switch in accordance with the present invention as illustrated generally at 10 and includes a housing constructed of a base member 11 having an upstanding sidewall 12 which preferably is constructed integrally with the base member 11 to form a lower generalv ly cup shaped portion of the housing. Although the base 11 and upstanding sidewall 12 can be constructed of any material desired, preferably it is molded of an electrically nonconductive plastic material such as an epoxy resin. To complete the housing, there is provided a cover illustrated generally at 13 which includes atop plate 14 having a depending sidewall 15. The combination of the top plate 14 and the depending sidewall 15 form a generally inverted cup shape member which slips down over the lower cup shape portion of the housing in such a manner that the two sidewalls overlap. The combination of the cover 13 and the lower portion of the housing defines a cavity 16 to which access is provided through an aperture 17 in the top plate 14 of the cover 13.

A plurality of electrically conductive pin members 21 through 25 extend outwardly from the base 11 and provide electrical contact to stationary contact elements for example such as those shown at 26, 27 and 28. A rotary contact element illustrated generally at 31 is formed of a washer like portion 32 having an outwardly extended arm 33 preferably formed integrally therewith and is positioned upon a centerpost 35 extending upwardly and into the cavity 16.

A rotor or drive mechanism illustrated generally at 36 includes a main body portion 37 having a bore 38 provided centrally thereof which is adapted to receive centerpost 35. An upper extension 39 of the main body portion 37 of the rotor 36 extends through the aperture 17 in the top plate 14 of the cover 13 thus providing communication with the internal mechanism of the switch from outside the housing thereof. A slot or kerf 41 is provided in the upper member 39 for receiving an adjusting tool for actuating the rotary contact element 31. An outwardly extending flange 42 is provided as part of the rotor 36 and cooperates with a sealing washer 43 to prevent entry of contaminants or moisture through the aperture 17 in the cover 13. The sealing washer 43 also cooperates with the top portion of the upstanding sidewall 12 to preclude the entry of foreign contaminants through any space between the cover 13 and the sidewall 12 and base 11 of the housing.

A clearer understanding of the relationship of the various parts of the switch in accordance with the present invention may be obtained by the illustration of FIG. 2 to which reference is hereby made. As is illustrated in FIG. 2 the base 11 has a peripheral recess 51 therein which is adapted to receive the lower edge portion 52 of the depending sidewall 15 of the cover 13 in such amanner that the lower edge 52 is crimped into the recess 51 to thus aflix the cover 13 to the base 11.

As is also more clearly illustrated in FIG. 2, the electrically conductive pin members such as that illustrated at 24 are constructed of an integrally formed member which extends completely through base 11 and preferably which are insert molded into place at the time of the formation of the base 1 1. As is indicated, the pin members such as that shown at 24 include a flange 55 which is in engagement with the base 11. Extending upwardly from the flange 55 is the stationary contact 28 which forms a contoured surface 57. The contact surface 58 provided on the arm 33 of the rotary contact element 31 is designed to conform to the contoured surface 57 as will be more fully explained hereinafter. The rotary contact element also includes a pair of transversely extending cam surfaces as shown at 59 which cooperate with-the contoured surface 57.of the contact element 28 to insure firm reliable electrical continuity having low contact resistance between the contoured surfaces 57 and the contact surface '58. The function and further description of the cam-surfaces 59 will be provided below.

A central aperture 60 is provided in the washer like portion 32 of the rotary contact element 31 so that the rotary contact element 31 may be rotatably disposed on the centerpost 35 within the cavity 16 of the switch in accordance with the present invention.

As the rotary contact element 31 is moved into and away from engagement with contoured surface 57 on a stationary contact such as 28 the cam surfaces 59 cause the arm 33 to move up and-down. As the arm 33 approaches the contoured surface 57 the cam surface first causes the arm to move upwardly as shown by the arrow 62 into a recess 61 provided in the lower surface of the main body 37 of the rotor mechanism 36. As the arm leaves the contoured surface 57, it drops downwardly as illustrated by the arrow 63 so that the contact surface 58 is below the top most portion of the contour surface 57. It should however be understood that when the arm 33 moves downwardly as indicated. by the arrow 63, the movement is insufficient to cause any portion of the arm to contact the base 11 of the housing.

The centerpost 35 includes an outwardly flared portion 65 which is supported within a raised boss 66. extending upwardly into the cavity 16. Aflange 67 extends outwardly from an electrically conductive pin 68in such amanner it cooperates with the outwardly flared portion 65 to prevent axial movement of centerpost 35. As is illustrated in FIG. 2, various component parts of the pin 68 and the centerpost 35 are constructed integrally of an electrically conductive material. The outwardly flared portion 65 provides a shoulder 69 upon which the. washer like portion 32 of the rotary contact element 31 rests and moves as' it is rotated. The contact between the shoulder 69 and the lower surface of the rotary contact element 31 provides the electrical contact extending externally of the housing for the rotary element of the switch in accordancewith the present invention;

A bead 71 extends upwardly from the flange 42 on the rotor mechaninsm 36. As is clearly illustrated in FIG. 2 the sealing washer 43 is a resiliently deformable-rubber like flat annular washer which is sandwiched between the interior surface of the top plate 14 of the cover 13 and the uppermost surface of the bead 71 and the uppermost surface of the upstanding wall 12. As the lower edge portion 52 of the cover 13 is crimped into place in the recess 51 the sealing member forceably engages the upper surface of the bead 71 and performs two functions there- 4 by. The first of these functions performed by the bead 71 and the rubber like sealing washer 43 is to provide the seal to prevent the entry of contaminants through the aperture 17 as above referred to. The second of these functions is to apply a downward pressure against the rotor mechanism so as to firmly press the rotary contact 31 into intimate electrical contact with the shoulder 69 on the outwardly flared portion 65 of the centerpost 35 thus insuring good noiseless electrical contact. A tang 72 depends downwardly from the, main body portion 37 of the rotor and engages a recess or indentation in the rotary contact element 31 to cause movement thereof when the rotor is moved by an adjusting tool inserted in the kerf 41. Y

The construction of the indentation and the cooperation of the tang therewith is more readily seen by reference to FIG. 3. As is therein illustrated, the rotary contact element '31 includes a peripheral recess 75. Since the rotor is loaded against the top portion of rotary contact 31 and the contact is precluded from moving downwardly as a result of the shoulder 69 the tang 72 firmly engages the recess 75 and drives the rotary contact element 31 as the rotor is moved.

As is more clearly illustrated in FIG. 3, the stationary contact elements such as those illustrated at 26, 27 and 28 are disposed about the outer periphery of the cavity 16 formedwithin the housing. Preferably the stationary contact elements are evenly spaced and are spaced in such a manner that the rotary contact element breaks contact with one of the stationary contact elements before making contact with the next. It is however to be expressly understood that the reverse order could be arranged should a particular application be demanded so that the electrical contact between two adjacent stationary contact elements was formed before the electrical contact with the preceding stationary contact element was broken.

As was 'above referred to and as is particularly illustrated in FIG. 1, the arm 33 of the rotary contact element at its terminal end portion 76 is provided with a pair of transversely disposed cars 77 and 78. By reference to FIG. 4, the specific construction of these ears may be better 'determined by taking that figure in conjunction with FIG. 3. As is therein illustrated, the ears are-formed by stamping the terminal end portion of the arm 33 into a configuration generally on the order of a W-shaped end portion providing a contact surface area 79 which-conformsto the contour surface 57 on the contact 28. The cam'surface '59 as above described, and its opposed portion 59A are formed'by the underside of the cars 77 and 78 respectively and operate in such a manner that as the terminal end portion of the rotary contactelement approaches the contour surface157 the outer edge of the cam surface (for example, at 81) contacts the contoursurface, 57 at a point such as (for example, at 82) and as additional force is applied, wipes upwardly toward theuppermost portion of the contour surface 57 until the lowermost portion of surface 59 is beyond the center line of surface 57-. At this point, spring pressure inherent in the contact arm tends to cause the contact to snap into place as illustrated in. FIG. 4. Thewiping action which occurs as a result of thecooperation between the cam surface 59 and the contour-surface 58 assures that a clean electrical contact surface is presented and the pressure which is. accomplishedby biasing the contact arm 31 ina downward direction as viewed in FIG. 2 assuressuflicient contact pressureto provide very low resistance electrical contact thus insuring a very low minimum current.

. .There has thus been disclosed a miniature rotary switch element which has dimensions of approximately 250 mils in diameter and mils inthickness in a typical device and which has relatively few moving parts which are constructed and assembled in such a manner that an extremely rugged, reliable low contact resistance switching apparatus is provided. Although this invention has been presented by way of illustrating and describing a specific embodiment thereof in'detail, it is to be expressly understood that such description and illustration is not to be taken by way of limitation of the present invention, but that the invention is to be measured by the scope of the claims appended hereto.

What is claimed is:

1. A miniature rotary switch comprising:

(a) a housing defining a cavity therein,

(1) said housing including an integral base and upstanding sidewall, and

(2) a cover member;

(b) a plurality of discrete stationary contact elements each having a surface with a predetermined contour extending upwardly from said base into said cavity,

(1) said stationary contact elements each including pin members extending through said base and externally of said housing thereby to provide electrical contact to said contact elements;

(c) an electrically conductive post member extending through said base externally of said housing;

(,1) said post being disposed centrally of said base;

(d) a rotary contact element rotatably disposed upon said post and in electrical contact therewith;

(1) said rotary contact element having an elongated extension for contacting said stationary contact elements and a recess therein;

(2) said extension having a contact surface conforming to said predetermined contour to mateably receive said contoured surface, and a pair of cam surfaces extending outwardly from said contact surface and adapted to engage and wipe against said contoured surface upon movement of said extension; and

(e) a rotor having a downwardly directed tang rotatably mounted upon said post with said tang in engagement with said recess in said rotary contact element and extending through said cover, whereby upon actuation of said rotor said rotary contact element sequentially contacts said stationary contact elements.

2. A miniature rotary switch as defined in claim 1 in which said rotor further includes a recess formed therein, said recess being aligned with said elongated extension of said rotary contact element.

3. A miniature rotary switch comprising:

(a) a housing defining a cavity therein,

(1) said housing including an integral base and upstanding sidewall formed of electrically nonconductive material, and

(2) a cover member;

(b) a plurality of discrete electrically conductive pin members formed integrally with said base and extending therethrough,

(1) the upper end of each said pin member extending into said cavity and forming a contoured surface,

(2) said pin members being equally spaced about the periphery of said cavity;

(c) an electrically conductive post member extending upwardly from said base into said cavity and extend ing through said base externally of said housing;

( 1) said .post being disposed centrally of said base;

(d) a washer like member defining an aperture therein rotatably received upon said post,

(1) said washer like member defining a peripheral recess therein and an arm extending outwardly therefrom and formed as an integral part thereof,

(2) said arm terminating in a contact member having a surface conforming substantially to the contoured surface of said pin members and a pair of transversely extending cam surfaces adapted to engage and wipe against the contoured surface of said pin members,

(3) said arm being biased to provide firm contact between said contact surface and said pin mem bers 'but to preclude engagement of said base by the terminal portion of said arm when said pin members are not in contact therewith;

(e) a rotor having a downwardly directed tang rotatably mounted upon said post with said tang in engagement with said recess in said washer like member and extending through said cover, whereby upon actuation of said rotor said washer like member sequentially contacts said stationary contact elements; and

(f) a sealing member sandwiched between said cover and said rotor and the top surface of said sidewall,

(1) said cover being crimped to said base to load said cover against said sealing member and said rotor against said washer like member.

4. A miniature rotary switch as defined in claim 1 in which said base defines a peripheral recess thereabout, said cover includes a centrally apertured top plate and a depending sidewall, said depending sidewall being in overlapping engagement with said upstanding sidewall, and said sealing member is a flat annular rubber-like member in engagement with the interior of said top plate of said cover, and the lower edge of said depending sidewall of said cover is crirnped into said peripheral recess in said base.

' References Cited UNITED STATES PATENTS 2,986,611 5/1961 Rugeris 20011.21 X 3,255,319 6/1966 Paine 2001 1.11

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

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