US2883501A

US2883501A - Variable resistor contact blade tension adjusting means

Info

Publication number: US2883501A
Application number: US629765A
Authority: US
Inventors: Reginald P Paget
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-12-20
Filing date: 1956-12-20
Publication date: 1959-04-21
Anticipated expiration: 1976-04-21

Description

R. P. PAGET April 21, 1959 VARIABLE RESISTOR CONTACT BLADE TENSION ADJUSTING MEANS 2 Sheets-Sheet 1 Filed Dec. 20, 1956 INVENTOR REGINALD F! PAGET BY S/ Z: w HTTUENEY R. P. PAGET 2,883,501

VARIABLE RESISTOR CONTACT BLADE TENSION ADJUSTING MEANS A ril 21, 1959 2 Sheets-Sheet 2 Filed Dec. 20, 1956 IN VEN TOR. REGI LD R PAGET BY I LU 4ND cud...

HTTOENE'Y United States Patent VARIABLE RESISTOR CONTACT BLADE TENSION ADJUSTING MEANS Reginald P. Paget, Costa Mesa, Calif., assignor to the United States of America as represented by the Secretary of the Air Force Application December 20, 1956, Serial No. 629,765

4 Claims. (Cl. 201-56) This invention relates to variable resistors such as potentiometers and, more particularly, to means for adjusting the contact pressure or tension between a stationary contact member and an adjustable contact spring in order to compensate for inaccuracies in the forming of the contact spring and variations in the contact tension between the movable contact spring or blade and a stationary contact member or ring.

A further object is the provision of a simple adjusting means disposed intermediate the opposite ends of an elongated flexible electrical contact blade member and an adjustable support therefor for controllably bending a portion of the blade adjacent its supported end for adjusting the free or outer contact end of the blade to regulate the contacting tension thereof with a cooperating stationary contact member.

A further object is the provision of a mounting support for an elongated flat contact blade and means for controllably bending the blade between predetermined points adjacent its supported end to adjust the free contacting outer end of the blade to vary the contacting tension thereof on a circular stationary contact member.

A further object is the utilization of the tension adjusting means as a means for securing the blade on the adjustable support and bending the blade adjacent the adjusting means to vary the contacting tension of the free end of the blade on a stationary contact element.

A still further object involves reducing the crosssectional area of the contact blade adjacent the adjusting means to decrease the stiffness of the contact blade in such area.

Another object includes the provision of means for supporting a flat resilient elongated contact blade transversely of its longitudinal axis at spaced points adjacent a fixed end thereof and means for adjustably applying pressure to the blade substantially midway between said spaced points to flex the free outer end of the blade in the opposite direction for adjusting the contacting tension of the free end of the blade on a circular contact element.

Other objects and advantages of the invention will become apparent from the following description and accompanying drawings in which like reference characters refer to like parts in the several figures.

Figure 1 is a perspective view of a variable resistor incorporating the invention, parts being broken away to more clearly illustrate the invention, the casing being omitted.

Figure 2 is a fragmentary sectional view taken approximately on the plane indicated by line 2-2 in Fig. 1, looking in the direction of the arrows.

Figure 3 is a fragmentary sectional view taken approximately on the plane indicated by line 3-3 in Fig. 1, looking in the direction of the arrows.

Figures 4 and 5 are enlarged detail views of the contact blades shown in Figs. 2 and 3, respectively, forming part of the invention.

Referring more particularly to Fig. 1, the reference numeral 1 denotes an adjustment shaft, which is adapted 2,883,501 Patented Apr. 21, 1959 to be journalled in suitable bearing in a casing not shown. Concentn'eally surrounding the shaft 1 is a circular or spiral shaped resistance coil element 2 comprising a plurality of turns 3 about the central axis of the shaft 1, said turns 3 of the resistance coil element 2 being uniformly spaced apart a distance at least equal to the crosssectional dimension of the resistance turn 3 of the coil 2 to provide a space 5 between the coils 3 having a similar dimension as the resistance element.

A rotor 6 is carried by the shaft 1 and preferably splined thereto to turn about the axis of the shaft 1. The rotor 6 is formed with an elongated guide block portion 7 traversing the coils 3 in inwardly spaced relation thereto.

A contact support element 8, formed with a guide channel 9 therein is slidably disposed on said guide block portion 7 for longitudinal adjustment between the rotor 6 and the convolutions of the resistance coil 2. The support element 8 is formed with spaced outer guide elements 10 and 11 extending into the space 5 between the convolutions of the resistance coil element and is formed with

circular channels

12 and 13 straddling the coils 3, the grooves or

guide channels

12 and 13 engaging alternate turns or coils of the resistance element 2 and is provided with an intermediate channel or space 14 disposed under the coil or turn 3 located between the coils riding in the

guide channels

12 and 13. This intermediate channel accommodates a resilient contact blade 15, with its free end 16 disposed in sliding contact with the inner surface of the resistance coil 2. The inner end 17 of the blade 15 is secured to the end face 18 of the slide block 8 and is inclined through the space or channel 14 to dispose the free end 16 thereof in contact with the coil 2.

A transverse groove or channel 19 extends transversely across the end 18, as shown, with the inner end portion 17 of the contact blade 15 spanning the groove 19 in contact with the end 18 at opposite sides of the groove 19.

The end portion of the contact blade is apertured at 20, substantially over the center of the groove 19, and tension adjusting means, such as an adjusting screw 21, is passed through the aperture 20, and threaded into a threaded opening formed in the base of the groove 19 substantially midway between its side walls, the head of the screw engaging the outer surface of the contact blade to tension the blade toward the recess or groove 19. Adjustment of the screw 21 depresses the blade intermediate the supporting edges of the recess 19 to increase the tension of the free end of the blade 15 on the resistance coil 2.

A flexible conductor 22 connects the inner end 17 of the contact blade 15 to a second adjustable resilient contact blade 23. This second contact blade 23 is secured at its lower or fixed end 24 to an insulated support block 25 carried in a suitable complementary recess or notch 26 formed in the rotor 6.

The upper or contact end of the second contact blade 23 is bifurcated to provide spaced contacts 27 disposed at the upper end of the resilient blade portion 28 in equal radial displacement from the adjustment shaft 1.

A fixed resilient contact blade 29 is suitably secured to the casing (not shown) and is offset at 30 to pass the end of the guide portion 7 and carries a flat annular or ring portion 31 disposed to engage the contact elements 27.

The portion of the ring 31 which engages the contacts 27 is fiat, circular and concentric to the shaft 1, having a terminal adapted to be connected to one of a pair of electrical circuit conductors (not shown) while the other electrical input conductor is connected to one end of the resistance coil 2.

"sides of 'the notch. The opposite edge portions of the blade 23, between the opposite sides of the notch 32, are notched at 33 and also apertured at 34 substantially midway over the notch '32 to provide for greater flexibility of the contact blade portion spanning the notch 32. An adjustment screw 35 extending through the aperture 34 into a threaded opening formed in the base of the notch 32, the head of the screw engaging the outersurface of the blade. Adjustment of the screw 35 toward the notch 32 bends the portion of the blade 23 spanning the notch to move the contacts 27 of the blade into greater tensionin'g contactwith the slip ring contact member 31.

Loosening of either the screw 35 or the screw 21 reduces the tensioning contacts respectively of the free ends of the

blades

24 or 15 on the ring or resistance coil contacts 31 or '2.

The invention is shown and described in one embodiment for purposes of illustration, it being obvious that changes may be made thereon by those skilled in the art without departing from the spirit and scope of the invention as defined in the accompanying claims.

I claim:

1. -In a variable resistor, the combination of a resistance element providing a plurality of turns extending around an axis, there being a space between adjacent turns of the same configuration as said resistance element, a rotor journalled to turn about'said axis providing a channel traversing said turns, a'first contact means comprising a support element slidable along said channel, a first resilient contact blade carried by said support element having a free end engaging a turn of said resistance element, tension adjusting means between said blade and said support element for adjusting the tensional contact between said blade and said turn of said resistance element, means for advancing said support element along said resistance element during rotation of said rotor comprising a guide element carried by said support element and extending into said space to follow the convolutions of said resistance element, secondary contact means for establishing contact between one end of said resistance element and said first contact blade comprising a stationary contact blade having an annular contact ring surrounding said axis concentric thereto, an elongated resilient second contact blade secured at one end to said rotor in radially spaced relation to said axis and having a free end disposed in contacting relation with said contact ring, said rotor having a notch formed therein adjacent the secured end of said rotor carried second contact blade transversely thereof with the blade spanning the notch in contact with said rotor at oposite sides of said notch, and means for moving the portion of the blade spanning'the notch toward the notch to bend the blade to vary the tensional contact between the free end of said second contact blade and said contact ring.

2. A variable resistor as claimed in claim 1 in which said tension adjusting means for said first contact means includes a notch formed in said support element adjacent the end of the first contact'blade remote from said free end and transverse to said blade with said blade spanning said notch in contact with the support element at opposite sides of the notch and means between said first contact blade and said support element intermediate the ends of the cooperating notch for bending said first blade toward said notch for varying the tensional contact be tween the free end thereof and said resistance element.

3. Apparatus as claimed in claim 2, in which at least one of said contact blade portions spanning one of said notches is reduced in cross-sectional area intermediate the ends of the notch which it spans to cause the bending thereof to occur substantially midway between the ends of said notch.

4. Apparatus as claimed in claim 2 in which at least one of said resilient contact blades is formed with an aperture intermediate the sides of the notches and the side edges of the blade, and a tension adjusting screw threaded into the support element intermediate the sides of the notch and having a head thereon engaging the outer face of the blade intermediate the sides of the notch toward the base 'of the notch for bending the blade intermediate the'sides of the notch toward the base of the notch.

References Cited in the file of this patent UNITED STATES PATENTS 2,288,043 Stanton June 30, 1942 2,406,079 Krueger Aug. 20, 1946 2,454,986 Beckman Nov. 30, 1948 2,480,995 Armitage Sept. 6, 1949 2,486,931 Edwards et al Nov. 1, 1949 2,495,321 Gibbs et a1. Jan. 24, 1950 2,558,326 Van Dyke June 26, 1951 2,813,182 Van Alen Nov. 12, 1957