US 3346708 A
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Oct. 10, 1967 I E. E. MORRA 3,346,708 ROTARY SWITCH WITH ROLLER DETENT APPARATUS DIRECTLY BIASING CONTACT STRUCTURE INTO OPEN AND CLOSED POSITIONS Filed July 27, 1966 .INVENTOR. EDW. E. MORRA United States Patent 3,346,708 ROTARY SWITCH WITH ROLLER DETENT APPA- RATUS DIRECTLY BIASING CONTACT STRUC- TURE INTO OPEN AND CLOSED POSITIONS Edward E. Morra, 950 Terminal Way, San Carlos, Calif. 94070 Filed July 27, 1966, Ser. No. 573,439 2 Claims. (Cl. 200-11) The present invention relates in general to a switch and in particular to an improved switch for use in printed circuit board application.
The rapid development of printed circuitry for use in electronic manufacture has necessitated the development of many switches for use therein. As printed circuitry becomes more and more available for general commercial and military application, the need for an inexpensive but highly reliable switch has arisen. Such a switch must not only be inexpensive, but also have the reliability necessary to meet rigid military standards. Further, the switch must be extremely versatile and flexible from an electronic standpoint.
The main object of the present invention is to provide a highly reliable but inexpensive switch suitable for use in printed circuitry.
One feature of the present invention is to provide a switch suitable for use in printed circuitry that can easily be stacked close together for a high density printed circuit board configuration.
Another feature of the present invention is to provide a switch suitable for printed circuitry in which a minimum amount of wear due to friction occurs on the contact blades and/or the printed circuit conductors.
These and other objects and features will become apparent to a person skilled in the art of switching after a perusal of the following specification and drawings, of which:
FIGURE 1 is a cross sectional view of the improved switch,
FIGURE 2 is an exploded perspective view of FIG- URE l, and
FIGURE 3 is a perspective view of an alternative contact blade.
Referring to the drawings, there is shown a switch comprising an elongated rectangular shaft 11 extending through a rotor assembly 12, actuating ring 20 and printed circuit board 25.
Rotor assembly 12 comprises a flat disk 13 made of a dielectric material, a plurality of electrical contact blades 14, and a plurality of actuator balls 15. An opening is provided in the center of disk 13 to accommodate shaft 11 in a close tolerance fit. Actuator balls 15 are movably secured or housed in a plurality of housing cavities 16 provided around the periphery of disk 13. Housing cavities are cut into disk 13 to a depth greater than their width to permit only radial movement of balls 15 therein. The bottom of the side walls of housing cavities 16 are each provided with an inwardly directed lip 17. The back wall of housing cavities 16 are each slotted near the top side thereof to accommodate contact blades 14 therein. Contact blades 14 are a metallic, spring-like members having a generally double bended configuration. Several configurations of contact blades may be employed to provide either snap action or simple spring biasing. FIGURE 3 shows a snap action contact blade 14 that could be substituted for contact 14 if desired. The contact or free end of each blade is bifurcated in its preferred embodiment. The inward or fixed end of blade 14 may be generally convex in shape as it is forced into the slots in the back wall of cavities 16. This convex shape provides a resistance to any upward force and tends to maintain the blades in a semirigid position. A small tab 19 is provided near the fixed end of blade 14 to serve as a lock to prevent the blades 14 from being accidentally removed. When contact blades 14 are secured Within the cavities 16, actuator balls 15 are forced inwardly against the back wall thereof by downward bend of the blades 14 as best seen in FIGURE 1.
The bottom surface of disk 13 has a circular recessed area 18 formed therein to accommodate an actuating ring 20. Actuating ring 20 is made of a dielectric material and is provided with a plurality of detents 21 spaced around the outer periphery thereof. The upper surface of actuating disk 20 is adapted to be received within the circular groove 18 provided within the bottom surface of disk 13. In its normal at rest position, a portion of each actuating ball 15- is resting against the base of detents 21.
Actuating ring 20 is securely mounted on a printed circuit board 25 by a plurality of reference pins 26 extending therethrough. Reference pins 26 also function as limit stop pins and may be placed so as to limit rotation of the switch 10 at any detent point. A plurality of desired conductive traces 27 on printed circuit board 25 are shown as a typical illustration of printed circuitry for a switching arrangement.
Rotor assembly 12, actuating ring 20, and printed circuit board 25 are secured together on shaft 11 by any convenient means, for example, spring snap rings 28 adapted to fit within annular slots 29 in shaft 11. In the event stacked switches are desired, a single common shaft or a concentric shaft may be used.
During operation of switch 10, and when it is desired to change positions, shaft 11 is rotated moving rotor assembly 12 either clockwise or counter-clockwise as desired. A cam-like force is exerted outwardly on actuator balls 15 by the lobes of the detents 21 of actuating ring 20. This urges the actuating balls 15 radially outward, transferring force to the bottom side of contact blades 14, which in turn forces the outward fingers of contact blades to lift upward, breaking electrical contact between the contact blades 14 and the circuit board 25 as shown in phantom in FIGURE 1. As rotation continues, the next or adjacent detent point 21 on actuator ring 20 is reached. Contact blades 14, now in a biased position, will urge actuator balls 15 back into an at rest position against the back wall of cavity 16 and the base of detent 21, and contact blades 14 will return down to make electrical contact with the next contact position on the circuit board 25. As each switching occurs, a wiping action between the electrical contacts of contact clades 14 and the printed circuitry occurs. This feature allows good contact to be made and prevents excessive contact wear to preserve the metal surfaces. This becomes especially important when an expensive metal such as gold is used for the contact surfaces. The amount of wiping action may be changed by varying the surface are of each detent 21. A deep detent will give more wiping action if desired, and a shallow detent will pick up blades 14 almost immediately.
In its preferred embodiment it is expected that rotor assembly 12 would have a plurality of contact blades 14 to enable use of multiple pole switching. Each contact blade 14 is electrically independent of all other contact blades in the switch and each would have its own actuating ball 15 associated therewith. The use of bifurcated contact points on blades 14 permits nearly equal pressure to be exerted upon the contact points of circuit board 25, and allows for slight variations in surface height of circuit board 25.
It is considered that a skilled practitioner in the art of electrical switching could locate or position detents 21 in various positions around actuating ring 20 thereby permitting various switching possibilities. Also stacking of 3 a plurality of switch assemblies on a single shaft is contemplated as seen in FIGURE 2.
What has been shown is an inexpensive, versatile rotary switch having many advantages and improvements over state-of-the-art switches. It will become obvious to those skilled in the art that various changes and modifications may be made in the above switch without departing from the invention as defined in the following claims.
What is claimed is:
1. A rotary switch comprising in combination:
a fixed printed circuit board having a plurality of conductive traces thereon;
an actuating ring securely mounted upon said circuit board and having a plurality of spaced detents around the outer periphery thereof;
a rotor assembly movably mounted upon said actuating ring, said rotor assembly comprising a substantially circular member having a plurality of spaced housing cavities around the outer periphery thereof, a plurality of electrical contact blades each having one end fixed within each of said housing cavities and having a free end in movable electrical contact with the conductive traces of said circuit board, actuating means movably secured within each of said housing cavities in movable contact with the detents of said Cir actuating ring and said electrical contact blades and means for rotating said rotor assembly whereby a force is exerted on said actuating means by the lobes of said detents, said force being transmitted through said actuating means to said contact blades to force the free end thereof upward as said rotor assembly is rotated.
2. The rotary switch according to claim 1 wherein said actuating means includes an actuating ball, said actuating ball movably secured with said housing cavity, said housing cavity including a pair of side walls and a back wall, said side walls including lip members inwardly extending therefrom.
References Cited UNITED STATES PATENTS 2,724,033 11/1955 Lagon 200-1121 X 2,847,523 8/1958 Van Amelsfort 200-11.10 3,032,618 5/1962 Johnson 200-153 X 3,215,790 11/1965 Young 20011 3,300,594 1/1967 Paine et al. 200-166 ROBERT K. SCHAEFER, Primary Examiner.
H. HOHAUSER, Assistant Examiner.