US2881296A

US2881296A - Potentiometer constructions

Info

Publication number: US2881296A
Application number: US582381A
Authority: US
Inventors: Marlan E Bourns; Edward D O'brian
Original assignee: BOURNS LAB Inc
Current assignee: BOURNS LAB Inc; BOURNS LABORATORIES Inc
Priority date: 1956-05-03
Filing date: 1956-05-03
Publication date: 1959-04-07
Anticipated expiration: 1976-04-07

Description

April 1959 M. E. BOURNS ET AL POTENTIOMETER CONSTRUCTIONS Filed May 3, 1956 United States Patent 2,881,296 POTENTIOMETER CONSTRUCTIONS Riverside, and Edward D. OBrian, said OBrian assignor to Bourns Lab- Marlan E. Bourns,

Anaheim, Calif.; oratories, Inc.

This invention relates to new and improved potentiometer constructions. More specifically it relates to otentiometers including readout means so that the position of a wiper within a potentiometer may be determined through the use minimum of difficulty.

The terms miniature and sub-miniature are frequently mentioned in the electrical industry today because there is an ever increasing demand for electrical components and assemblies which are extremely small and light in weight. A great deal of work has gone into developing different types of so-called miniature and subminiature devices for a variety of purposes. In spite of this work there are, at present, no known small, compact units manufactured which combine a potentiometer with a readout member so that the relative adjustment or position of the wiper of the potentiometer can be readily determined by simple visual inspection.

A broad object of this specification is to provide a small, compact light-weight combined potentiometer and readout construction as briefly indicated in the preceding sentence. A further general object of the invention is to provide electrical instruments of this category which can be easily manufactured using established techniques, which are exceedingly reliable in use, and which are capable of withstanding a great deal of physical abuse.

Another object of the invention is to provide various means for actuating the readout means utilized as well as for simultaneously adjusting the potentiometer in accordance with an electrical signal. Thus, the instruments of this invention are extremely well adapted for use in various control applications where an analog quantity represented by an electrical current is used to adjust a potentiometer for any desired control purpose. The amount of such adjustment can, with the devices of this invention, be determined in a digital form by simple visual inspection of the readout means employed.

Other objects and advantages of the invention will apof such readout means with a pear to those skilled in the art to which this specification is addressed from a detailed examination of the remainder of this description, including the appended claims and the accompanying drawing, in which:

Fig. 1 is an isometric view of a potentiometer construction of this invention;

Fig. 2 is a cross sectional view in which certain parts are shown in elevation, taken at line 22 of Fig. 1;

Fig. 3 is a cross sectional view taken at line 3-3 of Fig. 2;

Fig. 4 is a cross sectional view taken at line 4-4 of Fig. 2; and

Fig. 5 is an isometric view showing the construction of a readout ring or wheel.

It is to be understood that the accompanying drawing is not to be considered as limiting the scope of this invention inasmuch as a number of differently appearing constructions can be readily created by skilled mechanics in the field to which this invention pertains by utilizing the features herein explained. Obviously various sizes, shapes, and arrangements of parts may be altered while retaining the mode of operation and construction involved with this invention.

As an aid to understanding the new potentiometer constructions of this invention it may be stated by way of an explanatory summary that each of these constructions involves a resistance element; a wiper positioned adjacent to the resistance element so as to be movable along it; means for causing said wiper to assume different positions along the length of the resistance element; and readout means operatively attached to said means for causing said wiper to assume different positions. The inventive concept back of the present application is more fully defined or summarized in detail by the appended claims.

The exact nature of potentiometer constructions of the present invention can be more fully explained by direct reference to Figs. 1 through 4 of the accompanying drawings. Here there is shown a device 10 of the present invention which includes a cylindrical metal housing 12, the ends of which are closed by non-conductive generally

circular plates

14 and 16 formed out of a phenolic or other equivalent composition. Around the periphery of each of these plates there is provided a flange 18 adapted to bear against the housing 12 so as to form a substantially sealed unit when these plates are secured to one another through the use of three shafts 20. The ends of these shafts'20 project through openings 22 in the

plates

14 and 16 and are threaded so that nuts 24 can be utilized to secure these plates and the housing 12 together.

Mounted upon the plate 16 which, if desired, may be considered a rear plate is a non-conductive ring 26, around the periphery of which there is located a curved, continuous groove 28 which forms the inner race for a ball hearing, as will be described in more detail presently. Positioned upon the ring 26 is a small reversible electric motor 30 which has a shaft 32 extending from the opposite end thereof. Screws 34 are employed to attach the ring 26 and the motor 30 to the plate 16. Other screws 34 are employed together with small cylindrical spacers 36 to position a small cylindrical speed multiplying device 38 of any desired internal construction upon the motor 30 so that this device 38 is axially aligned with the motor 30. The shaft 32 serves to connect the motor 30 and this device 38; it also serves to carry a small gear 40 which is employed as will be more fully explained later. A non-round driven shaft 42 extends from the device 38 along the axis of this device on the side opposite the motor 30 so as to fit within a correspondingly shaped socket 44 in a larger round shaft 46. The shaft 46 is rotatably supported within a cylindrical opening 48 in the plate 14, and carries a large drive gear- 50.

This drive gear 50 is designed so as to coact with an internal ring gear 52 formed within the interior of a first readout ring or wheel 54. Within the device 10 are four of these readout rings or Wheels of substantially identical construction except for certain minor details as will be explained later. For convenience of explanation these readout rings or wheels are designated as 54, 54', 54", and 54" respectively; as will be more fully apparent these wheels are used to indicate successive numbers, such as, for example, the numbers in a decimal fraction. At least one of the wheels are required with the invention as a readout means, and any desired number of these rings or wheels can be employed. All four of these readout rings or wheels are formed as indicated in Fig. 5 of the drawing so as to each include a centrally located internal flange 56. On one side of each of these flanges there is formed a continuous internal ring gear 52 as indicated in the preceding discussion. On the other side of each of these flanges 56 there is formed a segmental internal ring gear 58 which, in the form of the invention illustr'steaeitma'sroi 36 of a cirele around the interior of each" of these readout ring s'orwheels54f All of the read out rings or wheels 54 are preferably formed of a nontlu emate a su h as. s g gg e, n lis Q I Po i y. v 1011s M an. Numerals to 9a're'paint'edor otherwise applie on the exterior of each .of thesering's or wheels 5450 as to be equally spaced in o'rderfth'at he position of these wheels 54 maybe visually dete" "60' formed in a'line along the of transparent wi'dd wall of the housing 1 z.

The readout rings or'i'wlieels a're all supported with v respect to one another a'gainst undesiredmovement ment, and the centers of these spools 62 normally, bear against the flanges 56. Itlis considered obviousthat the various shafts 20 are spaced frorn one another a sufiicient amount so as toprevent shifting oi the readout rings or wheels 54in planes transverseto the axis of the housmg Within the device 7 n 5 eteaeri di l m ve th retra t w ned through a series 16 th I ll i title 0 .wh lsf5 i one another in accordance with -therotation of the preced- 7 ins readout. s n at wear -1 u fsfi se r-@09 5 6 rotatably mounted on a shaft supported within openings (not shown) in the plates ld and ldf Each ofthe ea SPOQIS 6. isib m dw t e d 7 ha ns e enera shape of gears so I by a segmental ring gear on orient the readout wheels the nt nu u ting, se .1 2 v wheel is operated so as H to turn this next adjacent ring or wheel. This mechanism of eorrelating the motion of a series of wheels in accordance with a predeterrnined that when one of these ends is engaged the next a ja e readou mathematical relationship enables these Wheelsto be used in designating the'digits in a nuniber Geneva cross or other indexing movements can be substituted for the specific gear type connection betwelen the various readout wheels 54 so long as snch means are locatedgenerally Q Q taiu mp et uni .I

within these wheels so v such other means are substituted care must be taken that these means do not nterfere with the other operative parts of the device 10.

One of these other parts is eyliridrical non;conduc tive support 72 formed ot ephenolic resin or similar eompo-.

sition so as to have grooves 74 similar to the groove 28 formed on the inside thereof in such 'amanner as to hold small ball bearings 76 in order to rotatably mount this support'72 on the ring 26' and'the deviee 38, Preferably the groove 28' and the 'groove 74 imrnediately adjacent thereto are formed as illustrated so that the ballbearings around the ring 26 serve to prevent shifting of the support 72 in'a direction along its axis. Small plugs 78 can be threaded within holes 80 in the support 72 for introducing the ball bearings 76 into either of the channels carrying these i s-j 4 Around the periphery of the support 72 there is located within the preferred embodiment of the device 10 a IO-turn helical'resistance elerrient 82. This element 82 in the form of the invention illustrated includes a corn tinuous "non-conductive, base 84 around which is wound resistance wire 86; other types ofresistance elements can be, employed. For mechanical stability it is preferred to locate the resistance element 82 so that at least half of its depth is secured within a helical groove. 88 in the sup port 72 by means ofa conventionaladhesive or the like.

A helical, slot-like groove,90 having the same pitch as.

the resistance element 82is formed adjacent to this resistance element within the exterior of the non-conductive support 72.

With this construction a small metallic contact member 92 having an extension 94 formed thereon is mounted upon a non-conductive block 96 so that this extension fits within the slot-like groove causing the block to slide along a shaft 98 secured between the

plates

14 and 16 from withinropenings (not shown) in each. The contact member 92 also has a curved resilient extension 100 designed to engage the resistance element 82 and another extension designed to engage the shaft 98 so that this shaft may serve as an electrical return.

The support 72 is rotated during the operation of the device 10 through the gear 40 coacting with another gear 104 held upon an idler shaft 106 positioned so as to extend between the motor 30 and the device 38. The gear 104 coacts with an internal ring gear 108 formed on a flange .of aring 110 secured to the interior of the support 72'as by .means of screws (not shown) or like equivalents. Electrical connection is made. to the ends of the resistance element 82 by meansof slip rings 112 mounted on the ends of the support 72 so as to beelectrically connected as by means of short wires (not shown) to the endsof this resistance element. One of these slip rings 112 is engaged by a brush 114 mounted upon the plate 16 so as to be connected directly to one of a series of terminals 116. The other of the slip rings 112 is designed to be engaged by means of another brush 114 (Fig. 3) mounted upon anon-conductive hollow brace 118 carried by the plates 14 and 16 A wire. 120 leading from the brush 114 engagingthis other slip. ring to another of the terminals 116 may be conveniently passed through, the brace 118.

Further, as desired, other slip -rings 115 or contact members may be located within the interiors of the readout rings, or wheels. Such other slip. rings or contact members can be interconnected in any desired pattern so that when engaged by brushes such as the brushes 114 various electrical devicesmay be actuatedin various sequential or other manners. Thus, conductors 115 having the general shape of slip rings having gaps formed therein on the interior of the readoutvwheel 54" can be used so as to cause either the motor 30' to stop rotation or to cause this motor to reverse its direction of rotation. The terminals 116 employed may be of any known category and vmay be arranged in various configurations with respect to .one another for convenient mountingin sockets or the like. 7 v

It is considered that the operation of the device 10 is essentially, obvious from the aforegoingdescription of the construction of this device. When the motor 30 is caused to be operated the support 72 is rotated and simultaneously the contact member 92 moves along the resistance element 82 disposed upon this support. Also, as the motor 30 is, operated the speed multiplying device 38, which, if desired, may be termed gearmeans, is actuated so as toturn the gear 50, turning the first readout ring or wheel 54. Once during every revolution of this member a gear spool'66 causes the second readout ring or wheel 54' to move a fraction of a turn. When the second readout ring or wheels 54 has been moved so as tofinish a complete ,turn the third readout .ring or wheel 54 is then turned a fraction of a. turn andso on until the fourth ring or wheel 54". is turned onecomplete revolution corresponding in a time interval to the period required ,for the contact member 92 to move completely along the resistance element 82. It will be realized fromthe aforegoing description that the device 10 is essentially a very compactefiective gear trains are attached to shafts projecting from each end of it to operate the readout wheels and the support 72. It is possible to replace the motor 30 with various other structures for causing rotation of a known category. Further, it is possible in some devices utilizing a series of concentrically mounted members as herein defined to incorporate an amplifier within certain of the members utilized. If desired the entire device may be mounted directly upon a small amplification unit used to operate the motor 30. Since this device 10 is, as formed, entirely reversible it is very advantageous for many applications. Obviously a five or other number of turn resistance element can be used instead of the specific resistance ele-- ment shown. With any construction of this invention care must be taken that the readout means and the potentiometer wiper are operatively interconnected so that they are both actuated simultaneously in accordance with a desired mathematical pattern or interrelationship.

Because of the fact that a large number of modifications such as are indicated above may be made in the structure shown without departing from the essential features of this invention, the appended claims are to be afforded wide scope, and are not to be considered as being limited by the specific construction disclosed.

We claim:

1. An electrical instrument of the class described which includes: a resistance element; a wiper mounted adjacent to said resistance element so as to be capable of being moved along said resistance element; means for moving said wiper along said resistance element; a series of readout wheels rotatably mounted around said resistance element and said wiper; means for rotating a readout wheel of said series as said wiper is moved along said resistance element; and means for rotating the other of said readout wheels in said series in accordance with the rotation of said readout wheel.

2. An electrical instrument of the class described which includes: a support; a resistance element mounted on said support; means for moving said support; a wiper mounted adjacent to said resistance element so as to move along said resistance element as said support is moved, said wiper continuously engaging said resistance element as said support is moved; a series of readout wheels rotatably mounted around said resistance element and said wiper; means for rotating a readout wheel of said series as said wiper is moved along said resistance element; and means for rotating the other of said readout wheels in said series in accordance with the rotation of said readout wheel.

3. An electrical instrument of the class described which includes: a housing; a resistance element rotatably mounted within said housing; a contact member mounted within said housing so as to engage said resistance element as said resistance element is rotated; at least one readout wheel rotatably mounted in said housing around said resistance element and said contact member; and means interconnecting said resistance element and said readout wheel so as to simultaneously rotate said resistance element and said readout wheel so that the position of said contact member with respect to said resistance element can be determined by the position of said readout wheel.

4. An electrical instrument of the class described which includes: a housing; a cylindrical support rotatably mounted within said housing; a helical resistance element mounted upon said support; a contact member movably mounted within said housing adjacent said resistance element, said contact member engaging said resistance element; means for moving said contact member along said resistance element as said support is rotated; movable readout means mounted within said housing around said resistance element and said contact member; and means connecting said readout means and said support so as to move said readout means in accordance with the rotation of said support whereby the position of said contact member with respect to said resistance element can be determined by the position of said readout wheel.

5. A potentiometer construction which includes: a housing; a resistance element rotatably mounted within said housing; a contact member mounted within said housing so as to engage said resistance element as said resistance element is rotated; a series of readout wheels rotatably mounted within said housing; a reversible electric motor mounted within said housing; gear means connecting said resistance element to said electric motor so that as said motor is operated said resistance element rotated; gear means connecting the first of said series of readout wheels to said electric motor so that as said motor is operated said first readout wheel is rotated and means for rotating said readout wheels of said series in accordance with the rotation of said first readout wheel.

6. A potentiometer construction which includes: a housing; a cylindrical support rotatably mounted within said housing; a helical resistance element mounted upon said support; a contact member movably mounted within said housing adjacent said resistance element, said contact member engaging said resistance element; means for moving said contact member along said resistance element as said support is rotated; a series of readout wheels rotatably mounted within said housing around said support and said contact member; means for rotating the first readout wheel in accordance with the rotation of said support; means for rotating the remainder of said readout wheels of said series periodically in accordance with the rotation of said first readout wheel; and terminal means electrically connected to the ends of said resistance element and said contact member.

7. A potentiometer construction which includes: a housing; a hollow cylindrical support rotatably mounted within said housing; a resistance element mounted on said support so as to extend around said support; a con tact member mounted within said housing so as to engage said resistance element as said support is rotated; a series of readout wheels rotatably mounted within said housing so as to be positioned around said support and said contact member; an electric motor positioned within said support; and gear means connecting said motor to said readout wheels and said support so that said readout wheels are rotated to positions indicating the position of said contact member with respect to said resistance element when said support is rotated through the operation of said motor.

8. A device of the class described which includes: a housing; a hollow, cylindrical support rotatably mounted within said housing; a helical resistance element mounted upon said support; a contact member movably mounted within said housing adjacent to said resistance element, said contact member engaging said resistance element; means for moving said contact member along said resistance element as said support is rotated; a series of readout wheels rotatably mounted within said housing around said support and said contact member; an electric motor positioned within said support; gear means operated by said electric motor for rotating said support; means operated by said electric motor for rotating the first of said series of readout wheels in accordance with the rotation of said support; means for rotating the remainder of said readout wheels of said series periodically in accordance with the rotation of said first readout wheel; and terminal means electrically connected to the ends of said resistance element and to said contact member.

Harrison Oct. 13, 1931 George Jan. 30, 1951