US2858397A

US2858397A - Rheostat with fixed resistors

Info

Publication number: US2858397A
Application number: US503254A
Authority: US
Inventors: Willis W Littleton
Original assignee: International Resistance Co
Current assignee: International Resistance Co
Priority date: 1955-04-22
Filing date: 1955-04-22
Publication date: 1958-10-28
Anticipated expiration: 1975-10-28

Description

06L 1953 w. w. LITTLETON RHEOSTAT WITH FIXED RESISTORS 3 Sheets-Sheet 1 Filed April 22, 1955 ATTORNEY lOc 0 r.28,1958 -w. w. LITTLETQN ,85 7

RHEOSTAT WITH FIXED RESISTORS Filed April 22, 1955 3 Sheets-Sheet 3 Fig.7

BM 34 W IN VEN TOR. WILLIS W. LITTLETON ATTORNEY tent 2,858,397 Patented Oct. 28, 1958 RHEOSTAT wrrrr rixnn nnsrsrons Willis W. Littleton, Boone, N. (1., assignor to international Resistance Company, Philadelphia, Pa.

Application April 22, 1955, Serial No. 563,254

14 Claims. (Cl. 201-55) This invention relates to a rheostat, i. e., a variable resistor, such as a volume or tone control associated in a convenient manner with one or more fixed resistors as a single unit.

In many electronic circuits used in electronic apparatus, such as radio and television equipment, it is necessary to provide a variable resistor having in series therewith, one or more fixed resistors. Heretofore, this was accomplished by wiring the various separate fixed and variable resistor components together in the desired arrangement. However, this method has many disadvantages in the manufacture of such apparatus. The wiring of such units must be done by hand and is time consuming and expensive, in addition, it is space consuming.

There are available, variable resistors having a stop for limiting travel of the movable contact along the resistance path so that a portion of the path forms a fixed resistor in series with the variable resistors. However, such a unit provides only one fixed resistor and also shortens the length of the variable resistor path thereby decreasing the resistance value obtainable.

It is therefore an object of this invention to provide a variable resistor with one or more fixed resistors in a single compact unit. Another object is to provide a variable resistor with one or more fixed resistors in the single unit without shortening the resistance path of the variable resistor. A further object is to provide a combined variable resistor and fixed resistor unit which will economize the manufacture of electronic apparatus, such as radio and television equipment. Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts, which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

Fora fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Figure l is a perspective view of the unit;

Figure 2 is a sectional view of the unit;

Figure 3 is an end view of the unit without the cover looking from left to right in Figure 2;

Figure 4 is a plan 'view of the fixed resistor element;

Figure 5 is a plan view of the variable resistor element;

Figure 6 is a semi-diagrammatic arrangement of the variable resistor and fixed resistors;

Figure7 is a circuit diagram of the resistor arrangement shown in Figure 6;

Figure 8 is a modified semi-diagrammatic arrangement of, the variable and fixed resistors;

Figure 9 is a circuit diagram of the resistor arrangement shown in Figure 8;

Figure 10 shows a further modified arrangement of the variable and fixed resistors; and

arrangement of the strips.

Figure 11 is a circuit diagram of the resistor arrangement shown in Figure 10. 7

Referring to Figure 2 of the drawing, the unit in general comprises a base plate 111 of an electrical insulating material. A fixed resistor element 11 coated with one or more resistance strips is mounted on one face of the base plate 1%. A variable resistor element 12 coated with a single resistance strip is mounted on the fixed resistor element 11 with the resistance strips on the two elements being insulated from each other. The ends of the strips on the fixed resistor element 11 are connected to the strip on the variable resistor element 12 and if desired, to each other to form the desired series or parallel A shaft generally indicated at 13 is rotatably supported on the base plate 10 to carry a contact which slidably engages the strip on the variable resistor element 12. Thus, a variable resistor is connected as desired with fixed resistors in a circuit arrangement.

Referring to Figures 1, 2 and 3, the unit in detail comprises an annular base plate 10 molded from a plastic having good insulation properties. The base plate 10 has a central aperture 10a and four ribs ltlb extending radially from and spaced around its periphery. Each of the ribs 10b has a hole therethrough. The fixed resistor element 11 comprises a C-shaped sheet 15 (Figure 4) of an insulating material having four

tabs

15a, 15b, 15c and 15d extending radially from and spaced around its periphery. These tabs are circumferentially spaced the same distance as ribs 19b on base plate 10 with two of the

tabs

15a and 15d being adjacent the free ends of sheet 15. Each of the tabs has a hole 152 therethrough. The sheet 15 is coated with one or more resistance strips in a manner to be explained later to complete the fixed resistor element 11 which is mounted on base plate 10 around aperture ltia, the tabs overlying the ribs 10b and the resistance strips facing away from the base plate 10.

The variable resistor element 12 comprises a C-shaped sheet 16 (Figure 5) similar to fixed resistor sheet 15 but having only two radially extending

tabs

16a and 16b adjacent its free ends.

Tabs

15a and 16b are circumferentiallythe same as

tabs

15a and 15d to be superimposed thereon and each has a hole 16c therethrough. Sheet 16 is coated with a resistance material in a manner to be explained later to complete the variable resistor element 12. This variable resistor element 12 is superimposed on the fixed resistor element 11 with

tabs

16a and 16b

overlying tabs

15a and 15d respectively and with the variable resistor strip facing away from the base plate 10. A U-shaped metal clip 17a fits over the end of the rib 10b

opposite tabs

15a and 16a, one leg of the clip fitting be tween tab 15a and tab 16a. A second U-shaped clip 17b fits over the rib 10b engaged by tab 15a in the same manner with a leg being similarly located between

tabs

15d and 16b. Each of the clips 17a and 17b has holes in its legs in alignment with the holes in the ribs and tabs. A headed metal rivet 18 fits through each set of aligned holes with the head 13a engaging the resistance strip on 'the variable resistor element 12. A metal terminal 19 fits on the other end of each rivet 18 and against clips 17a and 1752. An annular flange 13b on the other end of the rivets sandwiches the tabs, ribs, clips and terminals tightly together. Thus, the resistance strip on the variable resistor element 12 is connected to the resistance strips on the fixed resistor element 11 through the rivets 18 and U-shaped clips 17. Additional headed rivets 20 extend through the holes of

tabs

15b and 150 aligned with holes 100 in ribs 101) with the heads 20a engaging the resistance strips on the fixed resistor element 12. Metal terminals 21 fit on the other ends of the rivets 20 which are then formed with annular flanges 20b to sandwich the tabs, ribs and terminals together.

A shaft 13 having a reduced end portion 13a extends through aperture lilo in base plate ltl with the reduced end portion 22a extending beyond the face of base plate which has the resistor elements attached thereto. A cylindrical metal bushing '23 having a mounting plate secured to one end thereof fits around shaft 13 so that the mounting plate engages the face of base plate ltd opposite the resistor elements. A snap ring fitting in an annular groove 13b in the shaft 13 engages the end of the bushing 23 to hold the bushing against the base plate lit). A contact carrier plate 26 of insulating material is mounted on reduced end portion (Figure 2) of the shaft and a metal contact member (Figure 3) is secured to the carrier plate 26 by lugs 27a extending through holes 26:; in the carrier plate 26. Contact member 27 has a pair of contact arms 27!) (Figure 2) slidably engaging the resistance strip on the variable resistor element 12 and a spring arm 27c slidably engaging a metal collector ring 28 which is mounted on the base plate 10 (Figure 2); collector ring 28 is connected to terminal 29. A drive plate 359 (Figure 2) is also mounted on reduced end portion 13a and abuts against the carrier plate 26. The end of the shaft 13 is flanged at 130 to form a force fit with drive plate 30. Drive plate 30 has a drive flange 30a fitting into a slot 26b in the carrier plate 26 and a stop flange Sill) (Figure 3). A cup shaped cover 31 fits around the reduced end portion 13a of the shaft and the elements mounted thereon and abuts against the base plate lb. The cover 31 has tabs 31a (Figure 1) extending over the edge of base plate 10 and bent into engagement with the face of the bushing mounting plate 2% to hold both the cover and the bushing 23 to the base plate 149. The cover 31 also has an indentation 31b (Figure 2) extending into the path of rotation of the stop flange 30b of the drive plate 3!? to limit rotation of shaft 13 so contact arms 27b will not move from the ends of variable resistor element 12.

Figures 6, 8, and 10 show various arrangements of the resistance strips on the fixed resistor element l1 and the variable resistor element 12. In the arrangement shown in Figure 6, the sheet 15' of fixed resistor element 11 is coated with a resistance strip which extends between

tabs

15a and 15b to form one resistor 32. Another resistance strip extends between

tabs

15c and 15d to form a second resistor 33 insulated from the first resistor 32. The sheet 16 of the variable resistor element l ft is coated with a resistance material extending between

tabs

16a and 16b to form a variable resistor 34-. One end 16a of variable resistor 34 is connected to end 15a of fixed resistor 32 through a rivet l8 and U-shaped clip 17a (Figure 2) as previously described and as diagrammatically indicated by dotted line 35. The other end 16b of the variable resistor 34 is similarly connected to end 15:! of fixed resistor 33 as diagrammatically indicated by dotted line 36. Thus, as shown in Figure 7, the variable resistor 34 has a fixed resistor 32 connected in series with one end and a fixed resistor 33 connected in series with its other end.

In the arrangement shown in Figure 8, the sheet 15 of fixed resistor element 11 is coated with a resistance strip extending between

tabs

15a and 15b to form a fixed resistor 32a and with a strip extending from tab 151; to tab 15c to form a second resistor 3'7 connected at one end to resistor 32a. The variable resistor element 12 is the same as previously described. In this arrangement one end 16a of variable resistor 34- is connected to one end 15a of fixed resistor 320 as indicated by dotted line 35a. As shown in Figure 9, this arrangement forms the variable resistor 34 with the fixed resistors 32:; and 37 connected in series with one end thereof.

In the arrangement shown in Figure 10, the resistor elements lit and 12 are the same as shown in Figure 6. However, in this arrangement, one end 15a of fixed resistor 32 is connected to one end 16!: of variable resistor 34 as again indicated diagrammatically by dotted line 35; end 15a is also connected to one end 15d of fixed resistor 33 as diagrammatically indicated by dotted line 37. This arrangement, as shown in Figure 11, provides the variable resistor 34 having in series therewith the parallel

fixed resistors

32 and 33,.

Other arrangements can be obtained by connecting the fixed resistors to each other and to the variable resistor to obtain a variety or" desired circuit arrangements. Sheet 15 may have more than two resistors by providing additional tabs on the sheet with resistance coatings therebetween which will be obvious from the above description. Thus, there is provided a single unit containing a variable resistor connected in any desired circuit arrangement with one or more fixed resistors. Furthermore, the construction of the unit provides for ease of manufacture of any desired circuit arrangement from the same combination of elements. For any change in the circuit arrangement it is only necessary to provide a fixed resistor element having the desired number and arrangement of fixed resistors while the remaining elements remain the same for each arrangement.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A resistor comprising the combination of a thin sheet of insulating material, a resistance material strip on said sheet, a second sheet of insulating material overlying said first sheet, a resistance material strip on said second sheet but insulated from the strip on said first sheet, a connection between one end of the strip on said first sheet and one end of the strip on said second strip and a contact movable along the strip on said second sheet.

2. A resistor comprising the combination of a thin sheet of insulating material, a plurality of resistance material strips on said sheet, a second sheet of insulating material overlying said first sheet, a resistance material strip on said second sheet but inulated from the strips on said first sheet, a connection between an end of the strip on said second sheet but insulated from the strips on said first sheet, and a contact movable along the strip on said second sheet.

3. A resistor comprising the combination of a sheet of insulating material, two resistance material strips on said sheet in spaced relation, a second sheet of insulating material overlying said first sheet, a resistance material strip on said second sheet but insulated from the strips on said first sheet, a connection between one end of the strip on said second sheet and one of the strips on said first sheet, a connection between the other end of the strip on said second sheet and the other of the strips on said first sheet, and a contact movable along the strip on said second sheet.

4. A resistor comprising the combination of a sheet of insulating material, two resistance material strips on said sheet, a second sheet of insulating material overlying said first sheet, a resistance material strip on said second sheet but insulated from the resistance strips on said first sheet, a connection between one end of the strips on said first sheet and one end of the strip on said second sheet, a connection between the other end of the one strip on said first sheet and the other strip on said first sheet and a contact movable along the strip on said second sheet.

5. A resistor comprising the combination of a sheet of insulating material, two resistance material stripsonsaid sheet in spaced relation, a second sheet of insulating material, a resistance material strip on said second sheet but insulated from the strips on said first sheet, a connection between one end of the strips on said first sheet and one end of the strip of said second sheet, a connection between said one end of said one strip and the other strip on said first sheet and a contact movable along the strip on said second sheet.

6. A resistor comprising the combination of a plate of insulating material having a hole therethrough, an annular thin sheet of insulating material mounted on a face of said plate and around said hole, a plurality of resistance material strips on said sheet, a second annular thin sheet of insulating material mounted on said plate and overlying said first sheet, a resistance material strip on said second sheet but insulated from the strips on said first sheet, means connecting an end of the strip on said second sheet to at least one of said strips on said first sheet, a rotatable shaft extending through the hole in said plate and a contact mounted on said shaft and slidably engaging the strip on said second sheet.

7. The combination as set forth in claim 6 in which the means for connecting the resistance material strips comprises a U-shaped metal clip fitting over the edge of the plate with one leg thereof contacting a strip on said first sheet and the other leg engaging the other face of said plate and a metal rivet extending through the sheets, plate and both legs of the clip and at one end engaging the strip on said second sheet and at the other end engaging the clip.

8. A resistor comprising the combination of a plate of insulating material having a hole therethrough, a thin annular sheet in insulating material mounted ona face of said plate and around said hole, two resistance material strips on said sheet in spaced relation, a pair of U-shaped metal clips fitting over the edge of the plate so that the legs of said clips straddle said plate, one of said clips having a leg contacting one of said strips and the other clip having a leg contacting the other of said strips, a second thin annular sheet mounted on said plate and overlying said first sheet, a resistance material strip on said second sheet having one end overlying the legs of one clip and the other end overlying the legs of said other clip, metal rivets extending through each end of the strip on said second sheet the strips on said first sheet, the legs of the clip and the plate, each rivet having one end engaging the strip on said second sheet and the other end engaging the clip, a rotatable shaft extending through the hole in said plate and a contact mounted on said shaft and slidably engaging the strip on said second sheet.

9. A resistor comprising the combination of a plate of insulating material having a hole therethrough, a thin annular sheet of insulating material mounted on a face of said plate and around said hole, a first resistance material strip on said sheet, a second resistance material strip on said sheet having an end engaging one end of said first strip, a U-shaped metal clip fitting over the edge of said plate so that the legs thereof straddle said plate, one leg of said clip engaging the other end of said first strip, a second thin annular sheet of resistance material mounted on said plate and overlying said first sheet, a resistance material strip on said second sheet having one end overlying the legs of said clip, aligned holes in the one end of the strip on said second sheet, the other end of said first strip, the legs of said clip and said plate, a metal rivet extending through the aligned holes having one end thereof engaging the strip on said second sheet and the other end engaging the clip, a rotatable shaft extending through said first mentioned hole in said plate and a contact mounted on said shaft and slidably contacting the strip on said second sheet.

10. A resistor comprising the combination of a plate of insulating material having a hole therethrough, a thin annular sheet of insulating material mounted on a face of said plate and around said hole, a first resistance material strip on said sheet, a second resistance material strip on said sheet having an end connected to one end of said first strip, a U-shaped metal clip fitting over the edge of said plate with the legs thereof straddling said plate, one of the legs of said clip engaging said one end of the first strip, a second thin annular sheet of insulating material strip on said second sheet having one end overlying said one end of the first mentioned strip, aligned holes through the one end of the strip on said second sheet, the one end of said first mentioned strip, the legs of the clip and the plate, a metal rivet extending through said aligned holes having one end engaging the strip on said second sheet and the other end engaging the clip, a rotatable shaft extending through said first mentioned hole in said plate, and a contact mounted on said shaft and slidably contacting the strip on said secon sheet.

11. A resistor comprising the combination of a plate of insulating material having a central aperture and a rib extending substantially radially from the periphery thereof, a thin annular sheet of insulating material mounted on a face of said plate and around said aperture, said sheet having a pair of substantially radially extending tabs spaced around the periphery thereof, one of said tabs overlying said rib, a resistance material strip on said sheet and extending along and between said tabs, a U- shaped metal clip fitting over the edge of said rib with the legs thereof straddling said rib, one of the legs of said clip engaging the portion of the resistance strip on the tab overlying said rib, a second thin annular sheet I of insulating material mounted on said plate and overlying said first sheet, a tab on said second sheet overlying the rib, a resistance material strip on said second sheet having one end extending along the tab thereof, aligned holes through the overlying tabs, rib and legs of said clip, a metal rivet extending through said hole having one end contacting the strip on the tab of said second sheet and the other end contacting the clip, a rotatable shaft extending through said aperture and a contact mounted on said shaft and slidably contacting the strip on said second sheet.

12. A resistor comprising the combination of a plate of insulating material having a central aperture and a pair of substantially radially extending ribs spaced around the periphery thereof, a thin annular sheet of insulating material mounted on a face of said plate and around said aperture, said sheet having four substantially radially extending tabs spaced around the periphery thereof, a first resistance material strip on said sheet extending along and between two of said tabs forming a fixed resistor, a second resistance material strip on said sheet extending along and between the other two tabs forming another fixed resistor, one tab of each strip overlying a rib, a U-shaped metal clip fitting over the end of'each of said ribs, each of said clips having its legs straddling its respective rib and one leg contacting the strip on the respective tab, a second annular sheet of insulating material mounted on said plate and overlying said first sheet, a pair of spaced tabs on said second sheet each overlying one of said ribs, a resistance material strip on said second sheet extending along and between the tabs thereof to form a variableresistor, aligned holes through said overlying tabs, ribs, and legs of said clips, a metal rivet extending through each set of aligned holes having one end contacting the variable resistor strip and the other end contacting the clip, a rotatable shaft extending through said aperture, and a contact mounted on said shaft and slidably engaging the variable resistor strip.

13. A resistor comprising the combination of a plate of insulating material having a central aperture and a rib extending substantially radially from the periphery thereof, a thin annular sheet of insulating material mounted on a face of said plate and around said aperture, said sheet having three substantially radially extending tabs spaced around the periphery thereof, one of said tabs overlying said rib, a first resistance material strip on said sheet extending along and between said one tab and an adjacent tab to form a fixed resistor, a second resistance material strip on said sheet extending along and between the third tab and said adjacent tab to form a second fixed resistor having a common tab with said first resistor, a U-shaped metal clip fitting over the end of said rib with the legs thereof straddling said rib, one leg of said clip contacting the strip on said one tab, a second thin annular sheet of insulating material mounted on said plate and overlying said first sheet, a tab extending from the periphery of said second sheet and overlying said rib, a resistance material strip on said second sheet having one end extending along the tab thereof to form a variable resistor, aligned holes through said overlying tabs, rib and legs of said clip, a metal rivet extending through said aligned holes having one end contacting the strip on said second sheet and the other end contacting said clip, a rotatable shaft extending through said aperture, a contact mounted on said shaft and slidably engaging said variable "resistor strip.

14. A resistor comprising the combination of a plate of insulating material having a central aperture and a rib extending substantially radially from the periphery thereof, a thin annular sheet of insulating material mounted on a face of said plate and around said aperture, a pair of substantially radially extending tabs spaced around the periphery of said sheet, one of said tabs overlying said rib, a resistance material strip on said sheet extending along and between said tabs to form a first fixed resistor, a second resistance material strip on said sheet forming a second fixed resistor, means connecting one end of said second strip to the strip on said one tab, a -U-shaped metal clip fitting over the end of said rib with the legs thereof straddling said rib, one of said legs contacting the strip on said one tab, a second thin annular sheet of insulating material mounted on said plate and overlying said first sheet, a tab on said second sheet overlying said rib, a resistance material strip on said second sheet having one end I tending along the tab thereof to form a variable resistor, aligned holes through said overlying tabs, rib and legs of said clip, a metal rivet extending through said holes having one end contacting the variable resistor strip and the other end contacting said clip, a rotatable shaft extending through said aperture, and a contact mounted on said shaft and slidably engaging said variable resistance strip.

References Cited in the file of this patent UNITED STATES PATENTS Beck Nov. 23,