US2974299A - Miniature variable resistance device - Google Patents

Miniature variable resistance device Download PDF

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Publication number
US2974299A
US2974299A US784561A US78456159A US2974299A US 2974299 A US2974299 A US 2974299A US 784561 A US784561 A US 784561A US 78456159 A US78456159 A US 78456159A US 2974299 A US2974299 A US 2974299A
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US
United States
Prior art keywords
base
shaft
cover
bushing
resistance element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US784561A
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English (en)
Inventor
Karl W Youngbeck
Charles R Goerg
Donald K Schuette
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Globe Union Inc
Original Assignee
Globe Union Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Globe Union Inc filed Critical Globe Union Inc
Priority to US784561A priority Critical patent/US2974299A/en
Priority to GB42465/59A priority patent/GB906445A/en
Priority to DEG28663A priority patent/DE1176241B/de
Priority to CH8221259A priority patent/CH375070A/de
Application granted granted Critical
Publication of US2974299A publication Critical patent/US2974299A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C10/00—Adjustable resistors
    • H01C10/30—Adjustable resistors the contact sliding along resistive element
    • H01C10/32—Adjustable resistors the contact sliding along resistive element the contact moving in an arcuate path

Definitions

  • This invention relates to improvements in variable electrical resistance devices, especially those of the type used with miniature electrical apparatus such as hearing -is smaller than those heretofore made and may be used for small transistor type hearing aids and other miniature applications.
  • Another object is to produce a highly compact, sensitive variable resistance device which is inexpensive to manufacture.
  • the first of these objects is accomplished by a novel arrangement of parts which reduces the size of the present device to a compactness previously unobtainable.
  • a thin, flat-sided, molded 'base is employed. All the flat terminals are molded into the base and project from an edge between the fiat sides.
  • the shaft for mounting the rotating element is also 'molded into the base and does not project beyond the It is connected outer or mounting side of the base. within the base to the center terminal.
  • the inside of the base has an annular groove in which is flushly seated and cemented a preformed resistance element. Such resistance element when made as a separate unit can be held to close electrical tolerances anduniformity.
  • the electrical connection between the ends of the resistor element and the outer terminals is accomplished by silver painting the ends of the resistance element and employing silver epoxy cement to secure the silvered ends of the resistance element to exposed surfaces of the ter-
  • the rotating element consists of a cover-knob which completely encloses the electrical elements and rides against the periphery of the base to effect a seal and prevent wobble.
  • the rotating elements consist of a contact spring and a center take-off spring which, with the cover, are staked to a bushing.
  • the bushing is rotatively mounted on the shaft by a retaining ring on the end of the shaft projecting through the bushing.
  • an efiicient variable resistor made in accordance with this invention may be less than 0.115 inch and its diameter less than 0.283 inch.
  • the second object is attained by use of a minimum number of small parts which are held in subassemblies during the molding operation to facilitate handling.
  • Fig. 1 is an enlarged top view of a variable resistor embodying this invention
  • Fig. 2 is an enlarged sectional view taken on the line 22 of Fig. 1 showing the contact spring in contact with the resistance element;
  • Fig. 3 is an enlarged sectional view taken on the line 3--3 of Fig. 1;
  • Fig. 4 is an enlarged bottom view of the movable element removed from the unit
  • Fig. 5 is an enlarged top view of the base with the movable element removed showing the contacts, resistance element and mounting shaft;
  • Fig. 6 is an enlarged fragmentary sectional view taken on the line 66 of Fig. 5;
  • Fig. 7 is a top view of the base showing the terminals and mounting shaft molded in place before detachment of the terminal strip;
  • Fig. 8 is a sectional view taken on line 8-8 of Fig. 7;
  • Fig. 9 is a bottom view of the base shown in Fig. 7.
  • the variable resistor exemplifying one form of this invention has a base 1 molded of any suitable nonconductive material such as phenol-formaldehyde or polyester molding compounds.
  • a shaft or post 2 and terminals 4, 5 and 6 are molded into the base and are relatively positioned as shown in Fig. 5.
  • the center-terminal 4 has a collar 34 in which the shaft is staked to assure a good electrical contact and provide a seat for anchoring the assembly in and strengthening the base.
  • the terminals 5 and 6 are molded into the base so that their inner ends, 9 and 10 respectively, underlie and are exposed in an annular groove 7 into which a resistance element 8 is flushly seated.
  • the resistance element consists of a blanked out laminated phenolic strip with resistance paint on its upper surface. Such preformed elements are well known to those skilled in this art and can be made to close electrical tolerances and uniformity. The ends of the resistance element are coated with silver paint to provide a good electrical path from, the bottom of the element at such ends to the ohmic path on its top. When the element is cemented in the groove 7, silver laden epoxy is placed between the ends 9 and 10 and the silvered ends of such element to establish a good electrical connection between the terminals 5 and 6 and the resistance element 8 as shown in Fig. 6. The arrangement of flat terminals molded in the thin, flat-sided base and projecting from one edge of such base permits the thickness of the base to be kept at a minimum. In
  • the flat bottom of the base is cemented to the chassis of the hearing aid or the like. In other installations it is advisable to have locating nibs 39 projecting from the base to accurately determine the location of the unit.
  • a terminal carrier strip 32 with spaced openings 33 has groups of properly spaced terminals 4, 5 and 6 blanked out as integral parts. Oblong ends 35 on the shafts 2 are fitted in openings in the collars 34 of terminal 4 and parts thereof staked over such collars as indicated at 36.
  • a multiple cavity casting die and an associated jig have external pins which fit in the spaced holes 33 to properly align the terminal groups with respect to each cavity. The inner ends of the terminals and 6 and oblong end 35 of the shaft rest on supports in the cavities to properly center them within the base when molded.
  • the die is closed and molding material forced into the cavities in a well known manner. As the jig and die are well known in the art they are not shown.
  • the important item is the use of a carrier strip onto which the bases are molded and by which they are carried for further assembly operations. Such operations may include the insertion and cementing of the resistance element 8 in the groove 7 and assembly of the moving elements hereinafter described. When assembly operations are completed the units are disconnected from the carrier strip 32 by severing the terminals at the desired places.
  • the moving elements mounted on the shaft 2 consist of a cover or operating knob '22, a contact spring 16 and a take-off spring 24 all fixedly secured by a headed bushing 11.
  • the bushing 11 has a central bore which rotatably fits freely on the shaft 2. At its lower end the bushing has a downwardly extending projection 14 (see Figs. 2 and 4) which engages with a stop 15 formed on the shaft 2 (see Figs. 3 and 5) to limit the rotation of the movable elements with respect to the resistance element 8.
  • the body of the bushing has opposed slots 12 (see Fig. 3) which receive tabs on the cover, contact spring and take-off spring to prevent relative rotation.
  • the bushing is fitted into an opening in the cover 22 with its headed end out.
  • Cover tabs 23 extending into such opening fit in the slots 12.
  • the cover 22 has a peripheral flange 31 which makes an enclosure for the resistance element, movable contact spring and take-oif spring. The end of such flange rides on the inner face of the base to form a dust seal and a broad bearing preventing wobble of the moving elements with respect to the shaft.
  • the contact spring 16 is substantially circular in shape. It has a C-shaped slot 17 which divides it into an outer ring 18 and inner disc 19. A nipple 21 formed on the outer ring 18 rides on the resistance element 8. A central opening in the disc 19 has a tight fit on the bushing 11 and tabs 20 on the edge of such opening fit snugly in the slots 12. The inner disc 19 seats snugly against the inner wall of the cover 22 and the outer ring 18 is biased out from the plane of such disc as shown to keep a spring pressed sliding engagement between nipple 21 and the resistance element 8 to provide a substantially noiseless electrical contact during variance in the electrical resistance of the device. 7
  • the shaft 2 is provided with an annular shoulder or face 3 flush with the inner side of the base 1 against which the take-off spring 24 has a spring biased sliding contact not variable during operation.
  • the takeoff spring 24 has a C-shaped portion 25 (see Fig. 4) and a substantially circular portion 26 joined by a short U- shaped bridge 28 (see Fig. 2). An opening in the portion 26 fits snugly over the bushing 11 and tabs 27 on such portion fit into the slots 12. The portion 26 rests flatly against the inner disc 19 and parts 13 (see Fig. 4)
  • the C-shaped portion 25 has its ends provided with dimples 29 and such portion is biased outwardly from the portion 26 to maintain a sliding electrical contact between such dimples and the shoulder 3.
  • the movable cover and contact spring assembly is rotatably held on the shaft 2 by a retaining ring 30 which is snapped into a groove near the outer end of shaft 2.
  • the tolerances are such that the wall of the cover is slightly deformed to maintain a sliding bearing between the edge of the flange 31 and the base 1. This is important not only to establish a seal against dust and lint but also to hold the cover 22 in selected position. In addition such bearing prevents the cover from wobbling when rotated thus insuring even contact between the sliding electrical connections.
  • variable resistor The operation of the variable resistor is in accordance with well known procedure.
  • the cover is rotated within the permissible limits to vary the resistance.
  • the problem solved by this invention is the reduction of size while maintaining necessary range, uniformity, long life, prevention of objectionable noise, and freedom from interference caused by dirt and lint.
  • a variable resistance device comprising, a molded base of insulating material having flat outer and inner sides, said inner side having a groove, a conductive shaft fixedly mounted on said base, and projecting from said inner side only, a resistance element secured in said groove, a plurality of terminals molded in the base, at least one of said terminals being in contact with said shaft and other of said terminals contacting said resistance element, a bushing rotatably mounted on said shaft, a cover secured to said bushing and having a downturned peripheral flange slidably bearing on said molded base, a contact spring secured to said bushing within the confines of said cover and said flange and biased into sliding contact with said resistance element, a takeoff spring secured to said bushing and to said contact spring within the confines of said cover and said flange and biased into sliding electrical contact with said shaft, and a retaining ring on said shaft to hold said bushing in place thereon.
  • variable resistance device the combination comprising, a thin fiat-sided molded base, a groove in one side of said base, a conductive shaft molded integrally into said base and projecting only from said one side, a resistance element in said groove, fiat terminals molded integrally into said base and projecting from an edge between said sides, one of said terminals being in electrical contact with said shaft, others of said terminals being in electrical contact with said resistance element, a movable assembly including a cover and a re sistance element contacting spring rotatably mounted on said shaft, said cover having a sliding bearing on said base, and means reacting between said shaft and said cover to keep said cover in sliding bearing with said base.
  • a miniaturized sensitive variable resistance device comprising, a flat-sided thin base having a peripheral flat bearing surface, a preformed resistance element in said base flush with one side thereof, a shaft fixed in said base and projecting from said one side, said shaft having a contact face flush with said one side, terminals connected to said resistance element and said shaft, a cover having a flange in flat bearing contact with said bearing surface, said cover being rotatably guided by said shaft, spring biased contacts carried with said cover and engaging said resistance element and said contact face, and means acting between said shaft and said flange to maintain it in sealing bearing engagement with said bearing surface.
  • a movable housing a substantially circular contact spring having a concentric C-shaped slot defining an inner disc with a central opening and an outer ring resiliently flexed out of the plane of said disc, a resistance element engageable nipple carried on said outer ring, a bushing in said opening fixedly mounting said disc to said housing, and a take-off, spring having a substantially circular portion with a central aperture surrounding said bushing and a O-shaped portion having take-off face engageable contacts on the extremities of said C-shaped portion and joined to said circular portion by a short bridge, said C-shaped portion being resiliently flexed at an angle with respect to said circular portion, said circular portion being 5 fixedly mounted on said inner disc by said bushing.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Adjustable Resistors (AREA)
US784561A 1959-01-02 1959-01-02 Miniature variable resistance device Expired - Lifetime US2974299A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US784561A US2974299A (en) 1959-01-02 1959-01-02 Miniature variable resistance device
GB42465/59A GB906445A (en) 1959-01-02 1959-12-14 Miniature variable resistance device
DEG28663A DE1176241B (de) 1959-01-02 1959-12-22 Steuerbarer Kleinwiderstand
CH8221259A CH375070A (de) 1959-01-02 1959-12-23 Regelbarer Widerstand

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US784561A US2974299A (en) 1959-01-02 1959-01-02 Miniature variable resistance device

Publications (1)

Publication Number Publication Date
US2974299A true US2974299A (en) 1961-03-07

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ID=25132808

Family Applications (1)

Application Number Title Priority Date Filing Date
US784561A Expired - Lifetime US2974299A (en) 1959-01-02 1959-01-02 Miniature variable resistance device

Country Status (4)

Country Link
US (1) US2974299A (de)
CH (1) CH375070A (de)
DE (1) DE1176241B (de)
GB (1) GB906445A (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3102173A (en) * 1958-12-12 1963-08-27 Damon Neil Electrical controls
US3119089A (en) * 1962-09-14 1964-01-21 Int Resistance Co Miniature potentiometer
US3124778A (en) * 1964-03-10 youngbeck
US3201737A (en) * 1962-11-13 1965-08-17 Bourns Inc Gear-adjusted variable resistor
US3205466A (en) * 1961-12-13 1965-09-07 Globe Union Inc Miniaturized variable resistor and switch
US3323093A (en) * 1964-07-03 1967-05-30 Litton Industries Inc Precision potentiometers
US3383635A (en) * 1967-11-13 1968-05-14 Continental Wirt Electronic Variable resistor
US3471820A (en) * 1967-03-14 1969-10-07 Sprague Electric Co Ceramic cased chromium-nickel variable resistor with undeformed contact
US4492950A (en) * 1983-03-01 1985-01-08 American Plasticraft Company Variable resistance assembly with improved contactor knob
GB2167981A (en) * 1984-11-21 1986-06-11 Piher Navarra Sa Adjustable potentiometers
US5592141A (en) * 1993-04-14 1997-01-07 Navarra De Componentes Electronicos, S.A. Miniature potentiometer

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0630290B2 (ja) * 1987-05-15 1994-04-20 株式会社村田製作所 可変抵抗器
JPH0630289B2 (ja) * 1987-12-10 1994-04-20 株式会社村田製作所 可変抵抗器
DE4335733C3 (de) * 1993-10-20 2001-07-26 Contelec Ag Biel Potentiometer
CN116864247B (zh) * 2023-08-14 2024-05-17 唐山恭成科技有限公司 一种贴片式陶瓷ptc热敏电阻调阻设备

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2176604A (en) * 1937-05-19 1939-10-17 Glen F Benkelman Resistor unit and method for making same
US2329949A (en) * 1941-11-12 1943-09-21 Sonotone Corp Rheostat device
US2479557A (en) * 1946-12-04 1949-08-23 David T Siegel Rheostat structure and method of molding
US2576044A (en) * 1949-03-02 1951-11-20 Sonotone Corp Rheostat

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB543919A (en) * 1939-11-09 1942-03-19 Sonotone Corp Improvements in rheostat devices
US2842647A (en) * 1954-03-18 1958-07-08 Globe Union Inc Adjusting means for resistance trimmers
GB796931A (en) * 1956-01-05 1958-06-25 Standard Telephones Cables Ltd Improvements in or relating to variable electric resistors

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2176604A (en) * 1937-05-19 1939-10-17 Glen F Benkelman Resistor unit and method for making same
US2329949A (en) * 1941-11-12 1943-09-21 Sonotone Corp Rheostat device
US2479557A (en) * 1946-12-04 1949-08-23 David T Siegel Rheostat structure and method of molding
US2576044A (en) * 1949-03-02 1951-11-20 Sonotone Corp Rheostat

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124778A (en) * 1964-03-10 youngbeck
US3102173A (en) * 1958-12-12 1963-08-27 Damon Neil Electrical controls
US3205466A (en) * 1961-12-13 1965-09-07 Globe Union Inc Miniaturized variable resistor and switch
US3119089A (en) * 1962-09-14 1964-01-21 Int Resistance Co Miniature potentiometer
US3201737A (en) * 1962-11-13 1965-08-17 Bourns Inc Gear-adjusted variable resistor
US3323093A (en) * 1964-07-03 1967-05-30 Litton Industries Inc Precision potentiometers
US3471820A (en) * 1967-03-14 1969-10-07 Sprague Electric Co Ceramic cased chromium-nickel variable resistor with undeformed contact
US3383635A (en) * 1967-11-13 1968-05-14 Continental Wirt Electronic Variable resistor
US4492950A (en) * 1983-03-01 1985-01-08 American Plasticraft Company Variable resistance assembly with improved contactor knob
GB2167981A (en) * 1984-11-21 1986-06-11 Piher Navarra Sa Adjustable potentiometers
US5592141A (en) * 1993-04-14 1997-01-07 Navarra De Componentes Electronicos, S.A. Miniature potentiometer

Also Published As

Publication number Publication date
GB906445A (en) 1962-09-19
CH375070A (de) 1964-02-15
DE1176241B (de) 1964-08-20

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