Rotary potentiometer with speed reduction gearing

Abstract

.Iadd.A rotary potentiometer with speed reduction gearing. A multi-tap closed loop distributed impedance is coupled by a mechanical configuration including a shaft to selected taps on an autotransformer. The mechanical coupling configuration permits the output from the wiper on the closed loop distributed impedance to change as a function of shaft position and to jump from one end of the autotransformer to the other while the shaft is continuously rotated in a given direction. .Iaddend.

I claim: 
     
       1. In electrical apparatus having a series of terminals, one of which is a reference terminal, means for maintaining a reference voltage on the reference terminal and voltages of predetermined values relative to the reference voltage on the respective other terminals along the series, means for deriving voltages intermediate those on the terminals including a continuous electrical path in the form of a closed loop of distributed impedance subdivided into sections by taps at at least three substantially equally spaced points thereon, switching means for connecting pairs of adjacent taps in rotation across successive pairs of adjacent terminals along the series, and a contact movable along that section of the impedance loop between the taps on said section connected to a first and second terminal, the improvement comprising switching means having at least three first conductive elements; each connected to one of said taps, a plurality of second conductive elements, each connected to one of said terminals, said first and second .[.terminals.]. .Iadd.conductive elements .Iaddend.comprising at least a portion of the surface of a substantially cylindrical drum; and electrical bridging means movable to interconnect each of said first conductive elements with one of said second conductive elements. 
     
     
       2. The apparatus of claim 1 wherein said first and second conductive elements are positioned on the inner surface of said drum. 
     
     
       3. The apparatus of claim 2 wherein said bridging means rotates about the longitudinal axis of said drum and against the inner surface thereof. 
     
     
       4. The apparatus of claim 1 wherein each of said first conductive elements is a circular washer-like annulus and is in stacking relationship with said second conductive elements, said second conductive elements being positioned to form at least one circular washer-like annulus, and electrically insulating material in separating relationship between said first and second conductive elements. 
     
     
       5. The apparatus of claim 1 wherein said electrical bridging means comprises a plurality of electrically conductive segments supported by a non-conductive rotor; rotor driving means comprising a driving shaft having thereon a bearing surface eccentrically disposed to the longitudinal axis of said shaft; first gear means concentric with said bearing surface and rotatable thereon; second gear means fixed with respect to said drum and encircling said first gear means, said second gear means being in concentric relationship with said driving shaft and having a portion of its inner surface meshing with a portion of the outer surface of said first gear means; and coupling means between said first gear means and said rotor for transferring the rotary motion of said first gear means to said rotor. 
     
     
       6. The apparatus of claim 1 wherein said bridging means comprises a substantially cylindrical rotor having on the surface thereof a plurality of spaced circumferential projections, said surface defining a groove substantially parallel to the longitudinal axis of said rotor and extending between said projections, and each of said projections defining a hole having an axis of symmetry coradial with and parallel to the longitudinal axis of said groove; rod-like locking means extending through and between said holes and positioned at least partially within said groove; and elongated, flat, electrically conductive blade means positioned between said locking means and said groove, the ends of said blade means being in contacting relationship with said first and second conductive elements. 
     
     
       7. The apparatus of claim 1 wherein said bridging means comprises a substantially cylindrical electrically non-conductive rotor having on the surface thereof a plurality of spaced circumferential projections, said surface defining a groove substantially parallel to the longitudinal axis of said rotor and extending between said projections, and each of said projections defining a hole having an axis of symmetry colinear with the longitudinal axis of said groove; rod-like electrically non-conductive locking means extending through and between said holes and positioned at least partially within said groove; and elongated, flat, electrically conductive blade means positioned between said locking means and said groove, the ends of said blade means being in contacting relationship with said first and second conductive elements. 
     
     
       8. Electrical switching apparatus comprising a first hollow cylindrical stator member; an inner rotor member; and rotor driving means; said stator member comprising at least one circular washer-like electrically conductive annulus in stacking relationship with at least one set of electrically conductive elements positioned to form a circular washer-like annulus, and electrically insulating material in separating relationship between said annuli and said elements; said rotor member comprising an electrically non-conductive cylinder having on the surface thereof a plurality of spaced circumferential projections, said surface defining a groove substantially parallel to the longitudinal axis of said rotor and extending between said projections, and each of said projections defining a hole having an axis of symmetry colinear with the longitudinal axis of said groove, rod-like electrically non-conductive locking means extending through and between said holes and positioned at least partially within said groove, and elongated flat electrically conductive blade means positioned between said locking means and said groove, the ends of said blade means being in contacting relationship with the inner surface of said cylindrical stator member; and said rotor driving means comprising a driving shaft colinear with said rotor having thereon a bearing surface eccentrically disposed to the longitudinal axis of said shaft, substantially circular driving means concentric with said bearing surface and rotatable thereon, annular track means encircling said circular driving means in concentric relationship with said driving shaft, fixed with respect to said stator and having a portion of its inner surface in engaging relationship with a portion of the outer surface of said circular driving means whereby rotation of said driving shaft causes said circular driving means to roll about the inner surface of said annular track means, and coupling means for transferring the rolling motion of said circular driving means to rotation of said rotor.