US3470333A - Multiposition rotary switch - Google Patents

Description

Sept. 30, 1969 Filed June 20, 1967 s. SCHNEIDER ET AL 3,470,333

MULTIPOSITION ROTARY SWITCH 2 Sheets-Sheet l ,5 i ge INVENTORS ROBERT L. FER L STANLEY SCI'N R ATTORNEY Sept. 30, 1969 s. SCHNEIDER ETAL MULTIPOSITION ROTARY SWITCH 2 Sheets-Sheet 2 Filed June 20, 1967 INVENTORS ROBERT L. FERRELL STANLEY SCFNEIDER w g A TORNEY' United States Patent US. Cl. 200-11 3 Claims ABSTRACT OF THE DISCLOSURE,

A multiposition rotary switch including an array of contact elements connecting with stationary terminals positioned through a base of a housing member enclosing a cavity. The contact carrying rotor is mountedwithin the cavity and adapted to move an electrically conductive wiper into contact with successive contact elements. In order to provide detent action and to positively locate the position of the wiper with regard to the contact elements there is provided a detent means including a camming surface on the rotor having a plurality of protruding-teeth arranged around the camming surface with depressions therebetween and a spring member having a convexshaped section mounted within the housing and forced against the teeth of the camming surface so that the convex-section of the beam spring tends to center itself between two adjacent teeth of the rotor camming surface.

The present invention relates generally to multiposition rotary switches and is more particularly directed to a precise detent indexing mechanism andmounting arrangement for the rotor of such a switch.

The trend toward smaller and smaller electronic components has created a need for a very precise multiposition rotary switch mechanism having a very positive indexing means for positioning and precisely locating the switch components. As a rotary switch becomes smaller and smaller the electrical contacts forming the switch elements are arranged closer and closer'together and the detent arrangement for positioning and locating the movable switching contact must be very precise. It must locate on the contact elements with little or no back-lash and must be precisely held in position once located. I

Accordingly, it is an object of the present invention to provide a new and improved rotary switching mechanism having a detent arrangement designed to virtually eliminate back-lash and movement of the switching contact after a switching operation.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention W11 be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the invention reference may be had to the accompanying drawings in which:

FIGURE 1 is a plan view of a multiposition rotary switch;

FIGURE 2 is a side view of the rotary switch of FIG- URE 1 illustrating the housing having terminal elements extending therefrom; 1

FIGURE 3 is an enlarged cross-sectional view taken essentially along line 3-3 of FIGURE 1;

FIGURE 4 is an enlarged cross-sectional view taken along line 4-4 of FIGURE 3 and illustrating the lower 3,470,333 Patented Sept. 30, 1969 side of the rotor and its electrically conductive contact member; I

FIGURE 5 is an enlarged plan view of the upper surfaces of the rotor; and

FIGURE 6 is an enlarged plan view of the switch with a portion of the rotary knob and cover lid broken away to show the detent mechanism.

Referring now to the drawings, there is shown in FIG- URES l and 2 a miniature rotary switch of a type adapted to be mounted on a circuit board or the like. The switch is generally denoted by the reference numeral 5, and includes a housing 6 formed of a base section 7 and a cover lid 8. Mounted parallel to the cover lid 8 for actuating the electrical components mounted within the housing cavity is a rotatable knob 9 which may be indexed to any of a plurality of positions.

As may best be seen in FIGURES 2 and 3, a plurality of stationary terminals 11 are mounted in an array within the base section 7 of the housing. Each of the terminals 11 and a center post terminal 11a are preferably molded into the base member 7 with one end thereof forming a contact pad or element 12 (12a on the end of center terminal 11a) exposed on the inner surface of the base member within the cavity 13. In the embodiment illustrated, the terminals 11 are concentrically located in a circle around the base terminal 11a which forms a common terminal for the switching mechanism. The terminals are preferably fabricated of a gold plated nickel or other suitable electrically conductive material. Base section 7 is' preferably molded of a plastic material such as glassfilled nylon or the like which is easily molded into the requisite shape with the terminals embedded therein. This material provides a number of advantages, such as appropriate self-lubricating qualities, non-conductivity, and is comparatively inexpensive.

Rotatably mounted within the cavity 13 is a rotor, generally designated by the reference numeral 14. The rotor carries an electrically conductive contact member 15 including a first movable contact or wiper 16 which is resiliently biased into contact with the contact elements 12. Wiper contact is disposed to engage successive contacts during rotation of the rotor within the cavity. The contact member 15 also includes at least one common resilient wiper 17 which is biased into electrical contact with the contact element 12a of the central terminal post 11a and remains in electrical contact therewith during rotation of the rotor. The common wiper 17 and its contact element 12a and terminal 11a form a convenient means for connecting the contact member 15 into an external electrical circuit. The contact member 15 is preferably formed of a one-piece construction, which may be stamped or otherwise formed from a sheet of spring-like material such as beryllium copper, or other suitable material. The contact member is preferably gold plated to assure good electrical contact or conductivity with the contact elements.

As may best be seen in FIGURE 4, the contact member 15, in the illustrated embodiment, is held in place on the rotor 14 by means of a protrusion 18 extending from the rotor over which edges 19 are bent outwardly when the wiper is assembled on the rotor. Edges 19 bite into the protrusion 18 of the rotor and retain the contact member 15 in place against the bottom surface of the rotor. In order to locate the contact member with respect to the rotor, the member is shaped to straddle a cylindrical flange 21 which extends downwardly from the rotor. As

. 3 will be seen in FIGURE 3, the wiper element 16 is positioned'externally of the downwardly extending cylindrical flange 21 and the common contact element 17 is positioned so that it extends within the confines of the cylindrically shaped flange 21 through a slot or opening 25 formed through the wall of the flange.

Means are provided for supporting the rotor 14 within the cavity 13 for rotation about an axis substantially normal to the base member 7. These means comprise, as may best be seen in FIGURE 3, the cylindrical flange 21 which extends into a mating circular groove or slot 22 formed in the base section 7. Groove 22 confines the rotor within the cavity and forms a bearing support for rotation of the rotor. The rotor 14 is also rotatably supported and axially. retained in position within the cavity 13 by the cover lid 8 of the housing. The cover lid is positioned above the rotor 14 and includes an opening 24 opposite from the base member through which the shaft 23 of the rotor extends. The cover lid is positioned over the exterior portions of the base member and securely attached thereto by means of an epoxy cement, or by ultrasonic welding techniques or other suitable means well known in the art. Beneath the surface of the cover lid 8 is positioned an O ring 26, which is positioned around the rotor shaft and recessed in a gland 27 formed in the upper surface of the rotor. The O ring 26, in cooperation with the gland 27, and the lower surface of the lid 8 seals the housing cavity 13 against environmental ingress and provides a certain amount of torque resistance to rotational movement of the rotor. Note that the cover lid 8 de presses the ring 26 within the gland 27 so that a certain amount of downward pressure is exerted thereon.

The rotor shaft 23, which is an integral part of the rotor 14, extends through the opening 24 and is attached directly to the knob 9. For this purpose a slot (see FIG- URE 29 is formed in the upper surface of the rotor shaft 23 which mates with a raised bar or shoulder 31 formed in a shaft hole 32 formed in the knob 9. The rotor shaft 23 is inserted in the knob opening 32 so that the raised bar 31 keys into the slot 29. The parts are then attached by means of a suitable cement, ultrasonically welded, or otherwise joined together.

A significant feature of the invention is a detent or indexing means for locating and retaining the contact member in any one of a plurality of predetermined positions with the movable wiper 16 in engagement with one of the contact elements. As will best be seen in FIG- URES 3, 5 and 6, this mechanism comprises a camming surface or toothed wheel 34 see FIGURE 5) which is an integral part of the rotor. The toothed wheel 34, as shown in FIGURE 5, comprises a plurality of triangular shaped teeth 36 separated by depressions or indentations 37 formed around the outer surface of the upper portion of the rotor. The apexes of the triangular shaped teeth 36 extend outwardly and engage a beam spring 38 during rotation of the rotor 14.

The beam spring 38, as may be seen in FIGURE 6, is preferentially fabricated of a material such as beryllium-copper alloy or the like. The spring is formed with .a central convex-shaped section 40 disposed so that it is convex in a direction toward the camming surface or toothed wheel 34 of the rotor. In the preferred embodiment illustrated, the convex section 40 of the spring is V-shaped with the apex 40a of the spring directed toward the camming surface. Note also that the outer sections 39 and 41 of the beam spring are also substantially V-shaped and that the very tips or end portions of the beam spring are mounted within or captured by slots v42 formed in the housing. The V-shaped sections 39 and 41 function to maintain indexing accuracy by allowing the spring tips 43 and 44 to remain in essentially the same position, even while the spring is distorted, thereby eliminating any translational movement of the spring with respect to-its mounting points.

The central convex section 40 is preferably formed so that the opposite sides or legs 45 and 46 thereof are swept back at a substantial angle and engaged by the tips or apexes of two adjacent triangular shaped teeth 36. As will be seen in the illustrated embodiment of FIGURE 5 the apex 40a of the V-shaped section 40 is normally directed inwardly toward an indentation 47 between the respective teeth when the camming surface is properly seated. Preferably, the spring section is formed at an obtuse angle slightly greater than the angle formed by connecting sides of the two adjacent teeth 36 of the camming surface. This permits the side legs 45 and 46 to be engaged by two adjacent teeth without the apex 40a.of the central spring section 40 touching the camming surface. This construction eliminates back-lash and causes the camming surface to seek a centrally located position between the adjacent teeth 36 in contact with the respective sides of the central V-shaped section.

As the rotor 14 is turned, the tip or apex of one tooth 36 moves along a side leg 45 or 46 (depending upon the direction of rotation) of convex section 40 and raises it until the tip passes the apex 40a of the spring section. Then the resilient force of the spring forces the apex 40a of the central section 40 into the identation or notch, such as notch 47, and advances the contact wiper 16 to the center of a contact element 12. By employing the illustrated embodiment of the mechanism, wherein the convex section 40 is V-shaped, it is virtually impossible for the contact wiper to become lodged between switch positions.

Any number of different contact position indicators may be employed with the device of the invention. For

example (but in no way limiting), the knob 9 may be provided with notches 51, as shown in FIGURE 1. Notches 51 facilitate knob rotation as well as divide the knob edge into any number of sections 52 which are equivalent to the number of the switch positions for the content element array formed within the device. A shallow slot 53, formed in the top of the knob 9, may be used to indicate the actual position of contact wiper 16. The pointer or index mark 54 on the side of the base member 7 may also be employed as a reference point to indicate the particular position in which the wiper contact 16 is electrically contacting one particular contact element 12.

While in accordance with the patent statutes there has been described what at present is considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, the aim of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention. I

What is claimed is:

1. A multiposition rotary switch comprising:

a housing defining a cavity and including a base having a circular groove formed therein and an array ofequidistantly spaced stationary terminals positioned therethrough externally of said circular groove and having contact elements exposed within said cavity, said housing having an opening through a wall thereof opposite said base;

a non-conducting rotor disposed within said cavity and having a shaft extending through said opening in said housing, said rotor including a projecting cylindrical flange extending into said circular groove in said base and supporting said rotor for rotation about an axis of rotation extending through said circular groove and said shaft protruding through said opening in said housing, said flange having a slot formed in side wall thereof; g

a central terminal post extending through said base and having a contact element exposed within said cavity on the surface of said base substantially surrounded by said circular flange;

a contact member attached to said rotor and having a resilient wiper contact disposed to engage said contact elements and a second resilient wiper contact extending through said slot in said cylindrical flange and engaging said contact element of said central post;

detent means for locating and retaining said contact member in any one of a plurality of predetermined positions with said contact member engaging a contact element comprising:

a camming surface on said rotor with a plurality of protruding triangular shaped teeth arranged concentrically around the axis of rotation of said rotor with triangular shaped depressions between each adjacent pair of said teeth;

a beam spring member having a V-shaped section disposed substantially centrally thereon and supported at both ends thereof in a side wall of said housing, said V-shaped section of said spring having side legs thereof bent at an angle greater than said angle of said apex of said triangular shaped teeth, said V-shaped section being resiliently retained against said teeth of said camming surface with the apex of said V-shaped section directed toward said teeth and depressions of said camming surface so that the side legs of said V-shaped spring section tend to center the apex of said V-shaped section between two adjacent triangular shaped teeth of said rotor camming surface.

2. The multiposition rotary switch defined in claim 1 in which said beam spring is supported at both ends thereof in slots formed in the side wall of said housing and with the only portion of said spring engaging said slots being the tips thereof.

3. The multiposition rotary switch defined in claim 2 in which said beam spring member is formed substantially in the shape of a central V-shaped section and two outer V-shaped sections attached on opposite sides of said central V-shaped section with said outer leg of said outer V-shaped sections engaging the side wall of said slots and with the central V-shaped section adapted to extend into the depression formed between two adjacent teeth of said rotor camming surface.

References Cited UNITED STATES PATENTS 3,255,319 6/1966 Paine 20011.11 3,283,105 11/1966 Locke et al. 3,301,971 1/1967 Johnson 200-11.23

ROBERT K. SCHAEFER, Primary Examiner M. GINSBURG, Assistant Examiner US. Cl. X.R. 200-166 PO-1O5O UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent N 3470333 Dated September 30, 1969 Robert L. Ferrell and Stanley Schneider Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 63 "non-conducting" should be non-conductive Column 6, line 12 "leg" should be legs Sil: i. u Adm SEALED JAN 6 -I9'i8 (SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. IR Attesting Offi Gomnissioner of Patents

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