US3350673A - Adjustable electronic component - Google Patents

Adjustable electronic component Download PDF

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Publication number
US3350673A
US3350673A US556745A US55674566A US3350673A US 3350673 A US3350673 A US 3350673A US 556745 A US556745 A US 556745A US 55674566 A US55674566 A US 55674566A US 3350673 A US3350673 A US 3350673A
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Prior art keywords
cavity
brush
rotor
top surface
casing
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US556745A
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Robert W Spaude
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Allen Bradley Co LLC
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Allen Bradley Co LLC
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H19/00—Switches operated by an operating part which is rotatable about a longitudinal axis thereof and which is acted upon directly by a solid body external to the switch, e.g. by a hand
    • H01H19/02—Details
    • 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 an adjustable electronic component apparatus such as is commonly employed for variable potentiometers, rheostats, capacitors, switches and the like wherein the electrical properties between two or more terminals may be varied and controlled.
  • the invention resides more specifically in adjustable electronic components that may be compacted within small overall dimensions for use in electronic circuits having a great number of components confined within small space limitations, or in other instances where compactness or light weight are of dominating concern.
  • the invention comprises a casing having a molded rotor positioned within the casing and rotational therein, the rotor includes a cavity opening transverse to said rotational axis and having an inclined top surface; a stationary base member positioned within the casing in alignment with the rotor, the base supporting a plurality of individually spaced apart leads which extend through the base to the exterior thereof, the base further supporting a plurality of electrical contact surfaces spaced apart in insulative relationship and facing the cavity, each of said contact surfaces electrically engaging the internal end of a lead; an electrically conductive brush member having a front plane and a back plane and having contacts on the front plane to simultaneously engage said contact surfaces on the front surface of said stationary base, the brush member positionedat least in -part wtihin said cavity and rotatable with the rotor such that when the rotor is in the proper rotational position said brush contacts bridge said front contact surfaces; resilient means positioned within said cavity, a rounded member simultaneously engaging the resilient means, the inclined top surface of the cavity and handicap
  • the present design provides a structure which may be very easily manufactured and wherebyall necessary soldering steps may be accomplished'prior to assembly of the various components into the casing.
  • the various components of the apparatus may be individually made in large quantities prior to assembly. Theneach individual component may be sorted and assembled without the requirement of special tools or fasteners.
  • the design is such that dimensional tolerances of the individualcomponents is somewhat relaxed without hindering the operation of the apparatus. Accordingly, the apparatus is economical to manufacture andis rugged in design while maintaining small dimensions.
  • the invention further provides an assembly whereby as the brush contacts wear, there is automatic compensation for the wear and a constant pressure'maintained between the brush and contact surfaces.
  • the brush and ball assembly constantly engage the brush such that as the contacts wear the resilient means, e.g., a spring, expands, thereby maintaining the rounded member, e'.g., a small ball, against the back plane of the brush and urging it against the stationary member.
  • FIG. 1 is a perspective view of an assembled potentiometer according to the principles of the present invention with the back and side surfaces most evident (assuming that the conductive leads extend from the front surface).
  • FIG. 2 is a cross-sectional view taken along the line 22 of FIG. 1.
  • FIG. 3 is a perspective view, in part broken away, of a rotor component incorporated in the potentiometer of FIGS. 1 and 2.
  • FIG. 4 is a cross-sectional view of the rotor component taken along the line 44 of FIG. 3.
  • FIG. 5 is a perspective view of a stator component carrying the electrical leads of the illustrated potentiom eter.
  • FIG. 6 is a perspective view of a conductive brush in: corporated in the illustrated potentiometer. The back surface of the brush is most evident with the front surface hidden from view.
  • FIG. 7 is a view in perspective of a resistive element of the potentiometer of FIGS. 1 and 2 and designed to accommodate the brush of FIG. 6
  • FIG. 8 is a perspective view of the stator component of FIG. 5 mounted with the resistive element of FIG. 7.
  • FIG. 9 is an illustrated exploded view in perspective of the potentiometer with the back surfaces of the various components most evident.
  • FIG. 10 is another exploded view in perspective of the potentiometer with the front surfaces of the various components most evident.
  • the embodiment of the invention as illustrated in FIGS. 1-10, inclusive, is in a form suitable for use as a miniaturepotentiometer of the type commonly employed in communication and control circuits.
  • the illustrated embodiment has been. constructed of dimensions in the order of in height and width with highly satisfactory mechanical :and electrical results.
  • Theapparatus is designated by a general reference character 1.
  • the potentiometer 1 includes a cup-shaped, non-oriented casing 2 having a circular recess therein with an end aperture 3 the center of which coincides withthe longitudinal axis of the casing.
  • the potentiometer serves as ameans of providing strength and maintaining the other components of the potentiometer in properly assembled position.
  • the casing 2 may be stamped from a metallic substance or molded of a plastic material.
  • the potentiometer further comprises a substantially cylindrical rotor component, designated by the general reference character 4, positioned coaxially within the casing 2.
  • the rotor 4 is preferably formed of a molded synthetic resin. Viewing the rotor 4 from the rear surface, best illustrated by FIGS. 3, 4 and 9, it carries three distinct steps 5, 6 and 7.
  • the step 5 forms the'outermost diametrical dimension and its diameter is slightly less than the internal diameter of the casing 2 thereby permitting the rotor 2 to rotate therein.
  • steps 7 and 6 engages the internal bottom surface of the casing 2 leaving a void space between the corner of the casing 2 and the rotor 4.
  • the step 7 is also of circular cross dimensions with the diameter slightly less than the diameter of the aperture 3 thereby permitting the rotor to protrude therethrough.
  • the rotor 4 carries a slot 8 within the area protruding through the aperture permitting a tool, for instance a screwdriver, to engage and adjust the rotor position.
  • the otherwise void space intermediate steps 5 and 6 carries a pliant O-ring 9.
  • the O-ring 9 which may be comprised of silicone, neoprene, or other type rubber, simultaneously snugly engages the step 6 and the interior surface of the casing 2 thereby providing a moisture seal while permitting rotational movement.
  • a cofiin shaped cavity 10 opens towards the front.
  • the rotor 4 also carries an intermediate step 11 between the outermost step 5 and the cavity 10.
  • the step 11 permits rotational engagement with respect to the stationary members of the potentiometer 1 which will hereinafter be described in detail.
  • the step 11 further carries a stop member 12 such that the rotor 4 cannot be continuously rotated in one direction.
  • the cavity 10 is molded to include a fiat bottom surface 15 which is parallel with the rotational axis and normal to the back planar surface of the rotor 4. Engaging the bottom surface 15 and at an angle slightly greater than ninety degrees is a first back plane surface 16.
  • the surface 16 extends pa-rt way up the back of the. cavity 10 where its top edge engages the bottom edge of a plane surface 17.
  • the surface 17 takes the form of an isosceles-triangularshaped plane facing the front of the cavity 10 and normal to the bottom surface 15.
  • Engaging each of the equal sided edges of the plane 17 is the back edge of a first top surface in the form of an inverted substantially V-shaped surface 19.
  • Each plane of the V-shaped surface 19 merges with a common apex which is positively sloped with respect to the rotational axis towards the cavity opening. In the illustrated embodiment, thevertex slopes at ap proximately 45 with respect to the axis of rotation.
  • the top surface 19 does not extend to the front surface.
  • the front edge of the plane 19 engages the back edge of a second top surface in the form of an inverted substantially V-shaped planar surface 20.
  • Each plane of the V- shaped surface 20 merges with a common apex which is parallel with the rotational axis.
  • the front edge of the plane 20 extends to the front surface of the rotor 4.
  • Flanking each side of the cavity 10 is a five-edged side plane 21.
  • the bottom edge of each plane 21 is common to a side edge of the bottom surface plane 15.
  • a rear edge of each plane 21 joins a side edge of the back planar surface 16.
  • a first top edge of each plane 21 joins a side edge of the V-shaped planar surface 19 and a second top edge engages the side edge of the V-shaped planar surface 20.
  • the front edge of each side plane of the surfaces 21 is common to the front surface of the rotor 4.
  • a stationary structure comprising a molded base 30 of insulative material, the extreme outer dimensions of which are circular coinciding with the internal dimensions of the casing 2.
  • the base 30 which is best illustrated by FIGS. 5, 8, 9 and 10, carries three apertures 32, 33- and 34 which are designed to accommodate lead wires extending therethrough.
  • the front portion of the molded base 30 (see FIG. 10) carries three stand-off feet 35 which, when a metal casing is included, insulate the potentiometer 1 from a mounting surface, for example a printed circuit board (not shown). Each of the feet 35 carry an exterior step 36 (FIGS.
  • the step 36 engages the edge of the casing 2 thereby controlling the distance the molded base 30 slides within the casing 2.
  • the front edge of the base 30 is flattened to rovide an. c e surface 4 37 (see FIGS. 2 and 10).
  • the surfaces 37 permit a metal casing 2 to be crimped and engage the surfaces 37 thereby structurally securing the casing 2 and molded stationary base 30 in turn preventing the apparatus from pushing apart.
  • each positioning ear 38 has arcuate outer dimensions coinciding with the internal radial distance of the casing 2, thereby permitting the casing 2 to fit over the ears and engage the steps 36 of the stand-off feet 35.
  • the interior dimensions of each positioning ear form a chord with the chords of adjacent positioning ears being substantially normal to each other. As will be hereinafter described, this permits placement of a square-shaped resistive element within the positioning ears.
  • the positioning ear 38 carries a molded tip 42. The tip 42 serves in conjunction with the mechanical stop 12 of the rotor 4 to prevent complete rotation of the rotor 4.
  • Intermediate the positioning ears 38 and 39 is an arcuate raised ledge 43.
  • the positioning ears 38 and 41 is another arcuate raised ledge 44 similar to that of 43 such that the aperture opening 33 is intermediate the raised edges 43 and 44.
  • a pair of insulating bumps 45 are intermediate the positioning ears 39 and 41 and intermediate the apertures 32 and 34.
  • the raised ledges 43 and 44 and the insulating bumps 45 are all of equal height and less than the height of the positioning cars 38, 39, 40 and 41, thereby establishing a flat plane intermediate the positioning ears on which a resistance element may be positioned and supported.
  • the ledges 43 and 44 and bumps 45 form the side surfaces of a well so that a set of conductive lead wires 46, 47 and 48 may protroude through the apertures 32, 33 and 34, respectively.
  • the leads 46, 47 and 48 preferably comprise a material, such as copper, which is highly conduc tive, highly bendable and highly susceptible to soldering and welding. As shown, the lead wires are bent at a angle and follow along the back surface of the base 30 within the well. The leads 46 and 48 each pass on one side of a bump 45 and the lead 48 passes between them, thereby insulating the leads from one another. The internal end of each lead 46, 47 and 48, inclusive, is turnedup at approximately 90". Obviously, the leads 46, 47 and 48 can be preformed before insertion in their respective apertures or molded within the stationary base 30.
  • the illustrated potentiometer carries a film-resistive element 60 (see FIGS 7, 8 and 9).
  • the element 60 comprises a square-shaped, supporting medium 61 generally comprised of an insulative ceramic material.
  • the medium 61 supports a first contact surface in the form of a firedon, arcuate, printed resistive track 62 comprised of a material having a designated resistance according to the desired design and material makeup. Opposite ends of the resistive track 62 terminate at termination pads 63.
  • the film resistive element 60 further carries a second contact surface in the form of a collector track 64 comprised of highly conductive material and illustrated in the form of a fired circular pattern. The center of the circular collector is substantially concentric to the center of the arcuate track 62.
  • the collector track 64 extends to a third termination pad 65.
  • the termination pads 63 and 65 are preferably of a material, eg gold or silver, which can readily withstand high temperatures and accommodate soldering or welding. Viewing FIGS. 5, 7 and 8, it may be further appreciated that by extending the termination pads 63 and 65 to the edge of the supporting medium 61, the leads 46, 47 and 48 may be engaged without providing holes within the medium 61 for the leads to protrude.
  • the termination pads 63 and 65 are designed to accommodate the turned-up ends of the leads 46, 47 and 48.
  • the embodiment illustrates a rectangular-shaped resistive element 60. Obviously, the structure may be designed to accommodate arcuate resistive elements or resistive elements of other shapes. However, with present technology, rectangular-shaped elements are generally more easily andeconomically realized.
  • the film resistive element 60 is designed to fit within the confines of the positioning ears 38, 39,40 and 41 and be supported by the ledges 43 and 44 and the insulating bumps 45 with the resistance track 62 facing the cavity of the rotor 4.
  • the resistance element is positioned such that the resistance track 62 is a relatively substantial radial distance from the casing 2 thereby realizing high leakageresistance between-the track and casing.
  • the corners of the supporting medium 61 are bare of resistance material or pads. Thus, during assembly, these corner areas can be contacted by a tool to aid the assembler. For example, a tool may clamp on two corners and also push on the'element 60 for assembly.
  • Adhering the resistance element 60 and leads 46, 47 and 48 to the molded stationary element 30, is an adhesive epoxy 66 which is disposed within the well formed by the ledges 43 and 44 and the insulating mumps 45 (see FIG. 2).
  • the epoxy-66 may be disposed within the well by placing a pellet or epoxy preform over one of the leads 46, 47 or 48 after the leads are in position. The pellet is then heated so that it melts and fills the well and the voids around the leads and the apertures 32, 33 and 34. Next, the resistance element 60 is positioned. Then the entire stationary assembly may be heated to cure the epoxy 66 and provide a secure unit.
  • the forming of the leads 46, 47 and 48, and anchoring them with the epoxy provides mounted leads which can withstand substantial abusive handling of the exposed ends without dislocation of the embedded ends in electrical contact with the resistance and collector tracks.
  • the assembly may then be placed in a solder bath thereby simultaneously providing a solder connection 67 between each of the pads 63 and 65 with the appropriate lead 46, 47 and 48.
  • a resilient'member in the form of a low load rate helical coil spring 70 having a long free length and many turns with the longitudinal axis perpendicular to the rotational axis of the rotor 4.
  • One end of the spring 70 -engages the bottom surface 15.
  • the other longitudinal end of the spring 70 cups a spherical member having a spherical surface portion, the member being ideally in the form of a ball 71.
  • the ball 71 simultaneously contacts the top surface 19 of the cavity 10 and the back surface of a single piece brush member 75 comprised of highly conductive carbon black material of negligible riesistance.
  • the brush 75 fits within the cavity and has back surface edge 76 inclined towards theback of the cavity 10 opposing the inclination of the back surface 19.
  • the back surface of the brush 75 carries a substantially V-shaped groove flanked by a pair of inclined planes 77, each of which contact the ball 71.
  • the brush 75 has a substantially V-shaped top surface 79 designed to accommodate the V-shaped top surface of the cavity 10.
  • the front" of the brush 75 carries two.
  • contact feet 80 and 81 separated a radial distance coinciding with'the radial distance separating the resistance track 62and the collector track 64 of the resistive element 60.
  • I H I Viewing FIG. 2 when the brush 75 is in'proper position, the combination ofthe spring 70 and ball 71 provides two component forces against the brush 75. .One component of force urges the brush toward and in contact with the resistance element 60 thereby maintaining. low contact resistance between the feet 80 and 81 and the associated resistance track 62 and collector track 64 while the other component of force is normal to the brush feet 80 and 81 thereby maintainingthe-brush feet 80 and 81 properly located on the tracks while rotation-adjustment takes place.
  • the force loading points of contact of the ball 71 with the inclined angular'top' surface 19 of the' cavity10 and the inclined back surface 77 of the brush "7 5 also provide location locking and keying of the brush 75 within the cavity.
  • the 45 angle of the surface 19 reflects the force of the spring 70.
  • the use of a grooved substantially V-shaped back surface 77 of the brush 75 and the substantially V-shaped surface 19 of the cavity permits the ball to make two points of contactwith each. This, in turn, permits the use of a brush with only two feet over the commonly used three foot brush, without sacrificing stability of the brush member.
  • the two foot brush facilitates small size and retains minimum or no backlash between the rotor and brush during rotation adjustment.
  • the springand ball 71 can be preassembled in the cavity 10 and be self-retaining, before the brush or stationary base 30 are assembled. When the ball 71 contacts the surface 20, there is little, if any, force tending to push the ball 70 out of the cavity 10.
  • the engagement of the resistance element 60 and the brush 75 maintains the ball 71 against the inclined top surface 19.
  • the ball 71 is permitted to travel along the inclined surface 19 between the normal surface 17 and the top surface 20.
  • the brush 75 maintains engagement with the res'istance element 60 even though the contacts and 81 wear or there are dimensional differences in the various components.
  • Consistency of brush-contact resistance depends largely upon the pressure of the brush. against the resistance and collector tracks.
  • the design permits the use of a low load rate spring 71 having along free length and many turns. Such a spring gives little force change with dimension change.
  • center contact foot 81 hasadimple depression 82 at the center.
  • the dimple 82 is intended to prevent poor contact with the collector track surface 64 which may otherwise result from no wearing (wiping action) and at the same time not create off-center. contacting surfaces that would cause a rotation force component to be transmitted to the brush.
  • the plane 16 makes an angle of slightly greater than with respect to the plane 15. This is intended to aid in retaining the longitudinal axis of the spring 70 stable while permitting the spring to expand and compress without rubbing against the back surface 16.
  • the stator 30 is assembled as previously discussed. That is, the leads 46, 47 and 48 are positioned and secured in place by the epoxy 66.. The. resistance element 60 is then positioned over the epoxy and the epoxy cured. Then the leads are soldered to the respective pads 63 and 65. Dipping into a p solder'bath has been found to be the most efiicient means of soldering. Obviously, solder stops may be used during the dipping process to maintain the solder only to the desired areas of the terminals 63 and 65. When these steps have been accomplished, the stator 30 appears as in FIG. 8. The spring 70 and ball 71 are then positioned in the cavity 10.
  • the O-ring 9 is then. placed within the recess of the casing 2 and the rotor assembly 4 slid into position until the step 6 engages the O-ring 9 and the step 7 protrudes through the opening 3. Then the brush 75 is set within the rotor cavity 10 in the proper location. The stator 30 is then slid within the casing 2 until the step 36 engages the end ofthe casing 2. At thispoint, the brush feet 80 and 81 are in engagement with the contact surfaces 62 and 64. Completing the assembly, the casing 2, if metallic, is crimped over the flattened edge surfaces 37.
  • the leads 46, 47 and 48 may be positioned to properly accommodate the grid patterns of standard printed circuit boards.
  • the standard grid pattern has holes spaced apart in multiples of 0.025 inch.
  • the above-described potentiometer is presently being constructed with the outlines of the leads forming an isosceles triangle.
  • the linear distance between the leads 46 and 47 is 0.200 inch with the lead 48 equally spaced from the leads 46 and 47 with the vertical distance being 0.100 inch.
  • the present invention provides a structure which is small in size while being easy to assemble. Also, the demensional tolerances, even though there is small size, may be relieved. The economic advantages realized by these features is obvious. Also, the various components of the casing, rotor and stator are in general non-oriented so that little assembly time is spent in positioning the various components with relationship to one another.
  • a switch may be realized by making one contact surface of highly conductive material and the other of at least two sections with one section being of highly conductive material and the other of insulative material.
  • the brush can rotate between bridging two conductive surfaces (on position) and bridging a conductive and insulative surface (off position).
  • a capacitive element could be realized by varying the dielectric value between the terminals as the rotor rotates.
  • An adjustable electronic component comprising, in combination:
  • a circular rotor having a diameter slightly less than the diameter of said recess positioned within the circular recess and rotational therein with the axis of rotation coincident with the longitudinal axis of the recess, the rotor having a cavity which cavity opens to the front face of the rotor, said cavity having a first top surface positively sloped with respect to the axis of rotation towards the front of said cavity;
  • the stationary base positioned With in the circular recess and in alignment with the rotor, the stationary base supporting a plurality of individual spaced apart electrically conductiveleads each having a shank portion emerging and extending outward from the base, the base further supporting a plurality of contact surfaces radially spaced apart in insulative relationship with one another, at least two of said contact surfaces electrically engaging the internal end of a conductive lead;
  • an electrically conductive brush member having a front surface facing the stationary base and a back surface, said front surface carrying spaced apart foot contacts with the distance between two of said foot contacts coinciding with the radial distance between two of said contact surfaces, one of said foot contacts making continuous wiping contact with one of said contact surfaces, said back surface of the brush extending at least in part within the cavity;
  • a spherical member simultaneously engaging one end of the compressible resilient member, the top surface of said cavity and the back surface of the brush, the spherical member simultaneously maintaining the resilient member under compression and urging the foot contacts of the brush member towards said contact surfaces whereby the brush member is maintained in locked position within said cavity and rotatable with the rotor, and
  • the electrically conductive brush member has an inclined back surface, with the angle of inclination opposing that of said first top surface of said cavity and sloping towards the back of said cavity.
  • the cavity includes a second top surface substantially parallel with the axis of rotation, the back edge of said second top surface joining the front edge of said first top surface.
  • the adjustable electronic component of claim 1 in which the first top surface is substantially V-shaped with two planes merging towards a common apex which apex is positively sloped with respect to the axis of rotation towards the front of said cavity.
  • first top surface is substantially V-shaped with two planes merging towards a common apex which apex is positively sloped with respect to the axis of rotation towards the front of said cavity, said spherical member contacting each plane of said first top surface;
  • said cavity includes a second top surface of substantially V-shape with two planes merging towards a common apex, the apex of said second top surface being substantially parallel with the axis of rotation and the back edge of said second top surface joining the front edge of said first top surface.
  • the electrically conductive brush member has a back surface of substantially V-shape with two planes merging towards a common apex and the spherical member contacting each plane of said back surface, said planes of said back surface of the brush being inclined at an angle opposing that of said first top surface of said cavity and sloping towards the back of said cavity, said brush further carrying a top surface of substantially V-shape for locking engagement with said second top surface of said cavity.
  • the compressible resilient member is a low load rate spring member having a relatively constant force of expansion while urging the spherical member along the first top surface.
  • the compressible resilient member is a low load rate helical spring having multiple turns, said spring being positioned within said cavity with the longitudinal axis of the spring substantially normal to the axis of rotation and with one longitudinal end supported by a bottom surface of said cavity which bottom surface is substatnially normal to the longitudinal axis of the spring.
  • the compressible resilient member is a low load rate helical spring having multiple turns, said spring being positioned within said cavity with the longitudinal axis of the spirng substantially normal to the axis of rotation and with one longitudinal end supported by a bottom surface of said cavity which bottom surface is substantially normal to the longitudinal axis of the spring, said spring having a relatively constant force of expansion while urging the spherical member along the first top surface.
  • said cavity includes a back surface joining the bottom edge of said first top surface and the edge of the 9- back surface, the bottom surface and back surface of the cavity joining at an angle greater than ninety degrees.
  • An adjustable electrical resistance component comprising, in combination:
  • a circular rotor having a diameter slightly less than the diameter of said recess positioned within the circular recess and rotational therein with the axis of rotation coincident with the longitudinal axis of the recess, the rotor having a cavity which cavity opens on the front face of the rotor, said cavity having a bottom surface plane radially spaced from the axis of rotation and a first top surface positively sloped with respect to theaxis of rotation towards the front of said cavity;
  • a stationary base positioned within the circular recess and in alignment with the rotor, the stationary base supporting a plurality of individual spaced and apart electrically conductive leads each having a shank portion emerging and extending outward from the base, the base further supporting a collector track and aresistance track radially spaced apartin insulative relationship with one another, said collector track and said resistance track being concentric and facing said cavity, said collector track electrically engaging the internalend of one of said conductive leads and said resistance track electrically engaging the internal'end of at least one of said conductive leads;
  • an electrically conductive brush member having a front plane facing the stationary base and a back plane, said front plane carrying spaced apart foot contacts with one foot contact making wiping engagement with said collector track and another foot contact making wiping engagement with said resistance track, said back plane of the brush extending at least in part within the cavity;
  • a spherical member simultaneously engaging one end of the resilient member, the first top surface of said cavity and the back surface of the brush member, the spherical member simultaneously maintaining the resilient member under compression and urging the foot contacts of the brush member towards their associate-d resistance and collector tracks;
  • variable electrical resistance component of claim 12 in which the electrically conductive brush member has a substantially V"-shaped back surface inclined toward the back of the cavity opposing the angle of in-- clination of said first top surface.
  • variable (electrical resistance component of claim 12 in which the brush member has a top surface and the cavity carries a second top surface, said top surface of the brush member and the second top surface of the cavity substantially coinciding in contour; whereby the spherical member urges said top surface into locking engagement.
  • variable electrical resistance component of claim 14 in which the first top surface of the cavity is substantially V- shaped with two planes merging towards a common apex which apex is positively sloped with respect to the axis of rotation towards the front of said cavity;
  • the second top surface is substantially V-shaped with two planes merging towards a common apex, the apex of said second top surface being parallel to the rotational axis and the back edge of said second top surface being common to the front edge of said first top surface;
  • the top surface of the brush member being of substantially V-shape for locking engagement with said second top surface; whereby the brush member can 10 travel within said cavity along the apex of said second top surface and said spherical member can travel along said top surface; and the compressible resilient member is a low load rate spring member having an axis of expansion normal to the axis of rotation and having a relatively constant force of expansion while urging the spherical member along the first top surface.
  • variable electrical resistance component of claim 17 in which said cavity has a back surface inter mediate said bottomvsurface and said first top surface, the back surface joining said bottom surface at an angle at least slightly greater than ninety degrees.
  • variable electrical resistance component of claim 15 in which said resistor track and collector track are'in the form of afilm supported by a planar substrate; theresistor track and collector track each carrying termination pads extendingto the peripheral edge of said planar substrate and electrically engaging the internal end of respective conductive leads.
  • variable electrical resistance component of claim 19 in which the supporting base forms a well flanked by supporting ledges of substantially equal height,
  • said terminal leads extending along said well with the internal ends advancing out of said well adjacent the periphery of said substrate and'a respective termination pad.
  • variable electrical resistance component of claim 20 in which the planar substrate is in the form of a rectangle.
  • An adjustable electronic component comprising in combination:
  • a brush actuator positioned within the casing and movable relative thereto, said actuator having a cavity which cavity opens to the front face thereof, said cavity having a top surface portion sloped towards the front of said cavity;
  • a stationary base positioned'to enclose the casing, the stationary base supporting a plurality of individual spaced apart electrically conductive leads each having a shank portion emerging and extending outward from the-base, the base further supporting a plurality of contact surfaces spaced apart in insulative relationship with one another, at least two of 'said contact surfaces electrically engaging the internal end of a conductive lead; i an electrically conductive brush member having a front surface facing the stationary base and a back surface,
  • said front surface carrying spaced apart foot contacts withthe distance between two of said foot contacts coinciding with the distance between two of said contact surfaces, one of said foot contacts making continuous wiping contact with one of said contact surfaces, said back surface of the brush extending at least in part within the cavity;
  • a compressible resilient member positioned within said cavity; a spherical member simultaneously engaging one end i of the compressible resilient member, the top surface portion of said cavity and the back surface of the brush, the spherical member simultaneously maintaining the resilient member under compression and 1 1 urging the foot contacts of the brush member towards said contact surfaces whereby the brush member is maintained in locked position within said cavity and movable with said actuator; and
  • first top surface portion is substantially V- s'haped with two planes merging towards a common apex which apex is sloped towards the front of said cavity, said spherical member contacting each plane of said first top surface;
  • said cavity includes a second top surface portion of substantially V-shape with two planes merging towards a common apex, the apex of said second top surface being substantially parallel with the back edge of said second top surface portion joining the front edge of said first top surface.
  • the electrically conductive brush member has a back surface of substantially V-shape with two planes merging towards a common apex and the spherical member contacting each plane of said back surface, said planes of said back surface of the brush being inclined at an angle opposing that of said first top surface of said cavity and sloping towards the back of said cavity, said brush further carrying a top surface of substantially V-shape for locking engagement with said second top surface of said cavity.
  • the compressible resilient member is a low load rate spring member having a relatively constant force of expansion while urging the spherical member along the first top surface 27.
  • the adjustable electronic component of claim 24 in which said cavity includes a back surface joining the bottom edge of said first top surface portion and the edge of the back surface, the bottom surface and back surface of the cavity joining at an angle greater than ninety degrees.
  • An adjustable electrical resistance component comprising, in combination:
  • a brush actuator positioned within the casing and movable relative thereto, said actuator having a cavity which cavity opens to the front face thereof, said cavity having a bottom surface plane radially spaced from the axis of rotation and a top surface portion positively sloped with respect to the axis of rotation towards the front of said cavity;
  • a stationary base positioned to enclose the casing, the stationary base supporting a plurality of individual spaced apart electrically conductive leads each having a shank portion emerging and extending outward from the base, the base further supporting a collector track and a resistance track spaced apart in insulative relationship with one another, said collector track and said resistance track being parallel and facing said cavity, said collector track electrically engaging the internal end of one of said conducive leads and said resistance track electrically engaging the internal end of at least one of said conductive leads;
  • an electrically conductive brush member having a front plane facing the stationary base and a back plane, said front plane carrying spaced apart foot contacts with one foot contact making wiping engagement with said collector track and another foot contact making wiping engagement with said resistance track, said back plane of the brush extending at least in part within the cavity;
  • a spherical member simultaneously engaging one end of the resilient member, the top surface portion of said cavity and the back surface of the brush member, the spherical member simultaneously maintaining the resilient member under compression and urging the foot contacts of the brush member towards their associated resistance and collector tracks;
  • variable electrical resistance component of claim 29 in which the compressible resilient member is a low load rate helical spring of long length and a plurality of turns, said helical spring having one end cupping the spherical member and the other end supported by said bottom surface of said cavity.

Description

c -31. 1961 Rw. SPAU E 3,350.613-
ADJUSTABLE ELECTRONIC COMPONENT Filed, June 10, 1966 2 Sheets-Sheet l M/VE/VTOR ROBERT w. SPAUDE Oct. 31, 1967 R. w. SPAUI DE 3,350,673
ADJUSTABLE ELECTRONIC COMPONENT Filed June 10, 1 966 2 Sheets-Sheet INVENTOI? ROBERT W. SPAUDE United States Patent Office 3,350,673 Patented Oct. 31, 1967 This invention relates to an adjustable electronic component apparatus such as is commonly employed for variable potentiometers, rheostats, capacitors, switches and the like wherein the electrical properties between two or more terminals may be varied and controlled. The invention resides more specifically in adjustable electronic components that may be compacted within small overall dimensions for use in electronic circuits having a great number of components confined within small space limitations, or in other instances where compactness or light weight are of dominating concern. The invention comprises a casing having a molded rotor positioned within the casing and rotational therein, the rotor includes a cavity opening transverse to said rotational axis and having an inclined top surface; a stationary base member positioned within the casing in alignment with the rotor, the base supporting a plurality of individually spaced apart leads which extend through the base to the exterior thereof, the base further supporting a plurality of electrical contact surfaces spaced apart in insulative relationship and facing the cavity, each of said contact surfaces electrically engaging the internal end of a lead; an electrically conductive brush member having a front plane and a back plane and having contacts on the front plane to simultaneously engage said contact surfaces on the front surface of said stationary base, the brush member positionedat least in -part wtihin said cavity and rotatable with the rotor such that when the rotor is in the proper rotational position said brush contacts bridge said front contact surfaces; resilient means positioned within said cavity, a rounded member simultaneously engaging the resilient means, the inclined top surface of the cavity and handicap resides in fabricating an assembly of such small components. The various components of the structures.
are generally very small and require tedious handling during the assembling process, especially where it is necessary to solder or weld various components. Also, manufacturing tolerances of the various components are generally critical due to the small size and when the tolerances are not held, the structure proves inoperable.
The present design provides a structure which may be very easily manufactured and wherebyall necessary soldering steps may be accomplished'prior to assembly of the various components into the casing. The various components of the apparatus may be individually made in large quantities prior to assembly. Theneach individual component may be sorted and assembled without the requirement of special tools or fasteners. Also, the design is such that dimensional tolerances of the individualcomponents is somewhat relaxed without hindering the operation of the apparatus. Accordingly, the apparatus is economical to manufacture andis rugged in design while maintaining small dimensions. a
The invention further provides an assembly whereby as the brush contacts wear, there is automatic compensation for the wear and a constant pressure'maintained between the brush and contact surfaces. The brush and ball assembly constantly engage the brush such that as the contacts wear the resilient means, e.g., a spring, expands, thereby maintaining the rounded member, e'.g., a small ball, against the back plane of the brush and urging it against the stationary member.
The above advantages and features of this invention will appear in the description to follow. In the description, reference is made to the accompanying drawings in which there is shown by way of illustration a variable resistive element in the form of a potentiometer incorporating the principles of this invention.
In the drawings:
FIG. 1 is a perspective view of an assembled potentiometer according to the principles of the present invention with the back and side surfaces most evident (assuming that the conductive leads extend from the front surface).
FIG. 2 is a cross-sectional view taken along the line 22 of FIG. 1.
FIG. 3 is a perspective view, in part broken away, of a rotor component incorporated in the potentiometer of FIGS. 1 and 2.
FIG. 4 is a cross-sectional view of the rotor component taken along the line 44 of FIG. 3.
FIG. 5 is a perspective view of a stator component carrying the electrical leads of the illustrated potentiom eter.
FIG. 6 is a perspective view of a conductive brush in: corporated in the illustrated potentiometer. The back surface of the brush is most evident with the front surface hidden from view.
FIG. 7 is a view in perspective of a resistive element of the potentiometer of FIGS. 1 and 2 and designed to accommodate the brush of FIG. 6
FIG. 8 is a perspective view of the stator component of FIG. 5 mounted with the resistive element of FIG. 7.
FIG. 9 is an illustrated exploded view in perspective of the potentiometer with the back surfaces of the various components most evident.
FIG. 10 is another exploded view in perspective of the potentiometer with the front surfaces of the various components most evident.
The embodiment of the invention as illustrated in FIGS. 1-10, inclusive, is in a form suitable for use as a miniaturepotentiometer of the type commonly employed in communication and control circuits. The illustrated embodiment has been. constructed of dimensions in the order of in height and width with highly satisfactory mechanical :and electrical results. Theapparatus is designated by a general reference character 1. The potentiometer 1 includes a cup-shaped, non-oriented casing 2 having a circular recess therein with an end aperture 3 the center of which coincides withthe longitudinal axis of the casing. As will be bereinafter further appreciated, the
' casing 2 serves as ameans of providing strength and maintaining the other components of the potentiometer in properly assembled position. Depending on the atmosphere of the actual application, the casing 2 may be stamped from a metallic substance or molded of a plastic material. The potentiometer further comprises a substantially cylindrical rotor component, designated by the general reference character 4, positioned coaxially within the casing 2. The rotor 4 is preferably formed of a molded synthetic resin. Viewing the rotor 4 from the rear surface, best illustrated by FIGS. 3, 4 and 9, it carries three distinct steps 5, 6 and 7. The step 5 forms the'outermost diametrical dimension and its diameter is slightly less than the internal diameter of the casing 2 thereby permitting the rotor 2 to rotate therein. The rise between steps 7 and 6 engages the internal bottom surface of the casing 2 leaving a void space between the corner of the casing 2 and the rotor 4. The step 7 is also of circular cross dimensions with the diameter slightly less than the diameter of the aperture 3 thereby permitting the rotor to protrude therethrough. The rotor 4 carries a slot 8 within the area protruding through the aperture permitting a tool, for instance a screwdriver, to engage and adjust the rotor position. As best illustrated in FIG. 2, the otherwise void space intermediate steps 5 and 6 carries a pliant O-ring 9. The O-ring 9, which may be comprised of silicone, neoprene, or other type rubber, simultaneously snugly engages the step 6 and the interior surface of the casing 2 thereby providing a moisture seal while permitting rotational movement.
Viewing the front surface of the rotor 4 (FIGS. 3, 4 and 10) a cofiin shaped cavity 10 opens towards the front. The rotor 4 also carries an intermediate step 11 between the outermost step 5 and the cavity 10. The step 11 permits rotational engagement with respect to the stationary members of the potentiometer 1 which will hereinafter be described in detail. The step 11 further carries a stop member 12 such that the rotor 4 cannot be continuously rotated in one direction. The cavity 10 is molded to include a fiat bottom surface 15 which is parallel with the rotational axis and normal to the back planar surface of the rotor 4. Engaging the bottom surface 15 and at an angle slightly greater than ninety degrees is a first back plane surface 16. The surface 16 extends pa-rt way up the back of the. cavity 10 where its top edge engages the bottom edge of a plane surface 17. The surface 17 takes the form of an isosceles-triangularshaped plane facing the front of the cavity 10 and normal to the bottom surface 15. Engaging each of the equal sided edges of the plane 17 is the back edge of a first top surface in the form of an inverted substantially V-shaped surface 19. Each plane of the V-shaped surface 19 merges with a common apex which is positively sloped with respect to the rotational axis towards the cavity opening. In the illustrated embodiment, thevertex slopes at ap proximately 45 with respect to the axis of rotation. The top surface 19 does not extend to the front surface. The front edge of the plane 19 engages the back edge of a second top surface in the form of an inverted substantially V-shaped planar surface 20. Each plane of the V- shaped surface 20 merges with a common apex which is parallel with the rotational axis. The front edge of the plane 20 extends to the front surface of the rotor 4. Flanking each side of the cavity 10 is a five-edged side plane 21. The bottom edge of each plane 21 is common to a side edge of the bottom surface plane 15. A rear edge of each plane 21 joins a side edge of the back planar surface 16. A first top edge of each plane 21 joins a side edge of the V-shaped planar surface 19 and a second top edge engages the side edge of the V-shaped planar surface 20. The front edge of each side plane of the surfaces 21 is common to the front surface of the rotor 4.
Within the recess of the casing 2 and aligned with the front of the rotor 4 is a stationary structure comprising a molded base 30 of insulative material, the extreme outer dimensions of which are circular coinciding with the internal dimensions of the casing 2. The base 30 which is best illustrated by FIGS. 5, 8, 9 and 10, carries three apertures 32, 33- and 34 which are designed to accommodate lead wires extending therethrough. The front portion of the molded base 30 (see FIG. 10) carries three stand-off feet 35 which, when a metal casing is included, insulate the potentiometer 1 from a mounting surface, for example a printed circuit board (not shown). Each of the feet 35 carry an exterior step 36 (FIGS. 2, 5 and 8) that extends over the end of the metal casing 2. The step 36, in turn, engages the edge of the casing 2 thereby controlling the distance the molded base 30 slides within the casing 2. Intermediate each of the feet 35, the front edge of the base 30 is flattened to rovide an. c e surface 4 37 (see FIGS. 2 and 10). The surfaces 37 permit a metal casing 2 to be crimped and engage the surfaces 37 thereby structurally securing the casing 2 and molded stationary base 30 in turn preventing the apparatus from pushing apart.
On the rear face of the base 30 facing the cavity 10, are four evenly spaced positioning ears 38, 39, 40 and 41. The ears each have arcuate outer dimensions coinciding with the internal radial distance of the casing 2, thereby permitting the casing 2 to fit over the ears and engage the steps 36 of the stand-off feet 35. The interior dimensions of each positioning ear form a chord with the chords of adjacent positioning ears being substantially normal to each other. As will be hereinafter described, this permits placement of a square-shaped resistive element within the positioning ears. It may be noted that the positioning ear 38 carries a molded tip 42. The tip 42 serves in conjunction with the mechanical stop 12 of the rotor 4 to prevent complete rotation of the rotor 4. Intermediate the positioning ears 38 and 39 is an arcuate raised ledge 43. Intermediate the positioning ears 38 and 41 is another arcuate raised ledge 44 similar to that of 43 such that the aperture opening 33 is intermediate the raised edges 43 and 44. Also intermediate the positioning ears 39 and 41 and intermediate the apertures 32 and 34 is a pair of insulating bumps 45. The raised ledges 43 and 44 and the insulating bumps 45 are all of equal height and less than the height of the positioning cars 38, 39, 40 and 41, thereby establishing a flat plane intermediate the positioning ears on which a resistance element may be positioned and supported. Furthermore, the ledges 43 and 44 and bumps 45 form the side surfaces of a well so that a set of conductive lead wires 46, 47 and 48 may protroude through the apertures 32, 33 and 34, respectively. The leads 46, 47 and 48 preferably comprise a material, such as copper, which is highly conduc tive, highly bendable and highly susceptible to soldering and welding. As shown, the lead wires are bent at a angle and follow along the back surface of the base 30 within the well. The leads 46 and 48 each pass on one side of a bump 45 and the lead 48 passes between them, thereby insulating the leads from one another. The internal end of each lead 46, 47 and 48, inclusive, is turnedup at approximately 90". Obviously, the leads 46, 47 and 48 can be preformed before insertion in their respective apertures or molded within the stationary base 30.
The illustrated potentiometer carries a film-resistive element 60 (see FIGS 7, 8 and 9). The element 60 comprises a square-shaped, supporting medium 61 generally comprised of an insulative ceramic material. The medium 61 supports a first contact surface in the form of a firedon, arcuate, printed resistive track 62 comprised of a material having a designated resistance according to the desired design and material makeup. Opposite ends of the resistive track 62 terminate at termination pads 63. The film resistive element 60 further carries a second contact surface in the form of a collector track 64 comprised of highly conductive material and illustrated in the form of a fired circular pattern. The center of the circular collector is substantially concentric to the center of the arcuate track 62. The collector track 64 extends to a third termination pad 65. The termination pads 63 and 65 are preferably of a material, eg gold or silver, which can readily withstand high temperatures and accommodate soldering or welding. Viewing FIGS. 5, 7 and 8, it may be further appreciated that by extending the termination pads 63 and 65 to the edge of the supporting medium 61, the leads 46, 47 and 48 may be engaged without providing holes within the medium 61 for the leads to protrude. The termination pads 63 and 65 are designed to accommodate the turned-up ends of the leads 46, 47 and 48. Also, the embodiment illustrates a rectangular-shaped resistive element 60. Obviously, the structure may be designed to accommodate arcuate resistive elements or resistive elements of other shapes. However, with present technology, rectangular-shaped elements are generally more easily andeconomically realized.
The film resistive element 60 is designed to fit within the confines of the positioning ears 38, 39,40 and 41 and be supported by the ledges 43 and 44 and the insulating bumps 45 with the resistance track 62 facing the cavity of the rotor 4. The resistance element is positioned such that the resistance track 62 is a relatively substantial radial distance from the casing 2 thereby realizing high leakageresistance between-the track and casing. It may be noted that the corners of the supporting medium 61 are bare of resistance material or pads. Thus, during assembly, these corner areas can be contacted by a tool to aid the assembler. For example, a tool may clamp on two corners and also push on the'element 60 for assembly.
Adhering the resistance element 60 and leads 46, 47 and 48 to the molded stationary element 30, is an adhesive epoxy 66 which is disposed within the well formed by the ledges 43 and 44 and the insulating mumps 45 (see FIG. 2). The epoxy-66 may be disposed within the well by placing a pellet or epoxy preform over one of the leads 46, 47 or 48 after the leads are in position. The pellet is then heated so that it melts and fills the well and the voids around the leads and the apertures 32, 33 and 34. Next, the resistance element 60 is positioned. Then the entire stationary assembly may be heated to cure the epoxy 66 and provide a secure unit. The forming of the leads 46, 47 and 48, and anchoring them with the epoxy provides mounted leads which can withstand substantial abusive handling of the exposed ends without dislocation of the embedded ends in electrical contact with the resistance and collector tracks. The assembly may then be placed in a solder bath thereby simultaneously providinga solder connection 67 between each of the pads 63 and 65 with the appropriate lead 46, 47 and 48.
Within the cavity of the rotor 4 is positioned a resilient'member in the form of a low load rate helical coil spring 70 having a long free length and many turns with the longitudinal axis perpendicular to the rotational axis of the rotor 4. One end of the spring 70-engages the bottom surface 15. The other longitudinal end of the spring 70 cups a spherical member having a spherical surface portion, the member being ideally in the form of a ball 71. The ball 71 simultaneously contacts the top surface 19 of the cavity 10 and the back surface of a single piece brush member 75 comprised of highly conductive carbon black material of negligible riesistance. (FIG. 6 is-an enlarged view of the brush 75.) 'The brush 75 fits within the cavity and has back surface edge 76 inclined towards theback of the cavity 10 opposing the inclination of the back surface 19. The back surface of the brush 75 carries a substantially V-shaped groove flanked by a pair of inclined planes 77, each of which contact the ball 71. The brush 75 has a substantially V-shaped top surface 79 designed to accommodate the V-shaped top surface of the cavity 10. The front" of the brush 75 carries two.
contact feet 80 and 81 separated a radial distance coinciding with'the radial distance separating the resistance track 62and the collector track 64 of the resistive element 60. I H I Viewing FIG. 2, when the brush 75 is in'proper position, the combination ofthe spring 70 and ball 71 provides two component forces against the brush 75. .One component of force urges the brush toward and in contact with the resistance element 60 thereby maintaining. low contact resistance between the feet 80 and 81 and the associated resistance track 62 and collector track 64 while the other component of force is normal to the brush feet 80 and 81 thereby maintainingthe- brush feet 80 and 81 properly located on the tracks while rotation-adjustment takes place. The force loading points of contact of the ball 71 with the inclined angular'top' surface 19 of the' cavity10 and the inclined back surface 77 of the brush "7 5 also provide location locking and keying of the brush 75 within the cavity. The 45 angle of the surface 19 reflects the force of the spring 70. Also, the use of a grooved substantially V-shaped back surface 77 of the brush 75 and the substantially V-shaped surface 19 of the cavity permits the ball to make two points of contactwith each. This, in turn, permits the use of a brush with only two feet over the commonly used three foot brush, without sacrificing stability of the brush member. The two foot brush facilitates small size and retains minimum or no backlash between the rotor and brush during rotation adjustment.
. Further, the second substantially V-shaped top plane 20 aids in the assembly process. The springand ball 71 can be preassembled in the cavity 10 and be self-retaining, before the brush or stationary base 30 are assembled. When the ball 71 contacts the surface 20, there is little, if any, force tending to push the ball 70 out of the cavity 10.
On the illustrated embodiment, the engagement of the resistance element 60 and the brush 75 maintains the ball 71 against the inclined top surface 19. The ball 71 is permitted to travel along the inclined surface 19 between the normal surface 17 and the top surface 20. Thus, the brush 75 maintains engagement with the res'istance element 60 even though the contacts and 81 wear or there are dimensional differences in the various components. Consistency of brush-contact resistance depends largely upon the pressure of the brush. against the resistance and collector tracks. To maintain substantially constant spring pressure, the design permits the use of a low load rate spring 71 having along free length and many turns. Such a spring gives little force change with dimension change. Thus, there is substantially constant contact pressure between the brush contacts 80 and 81 and the contact surface 62' and 64 throughout the fullrange of brush movement along the surface 19. It may be further noted that the center contact foot 81 hasadimple depression 82 at the center. The dimple 82 is intended to prevent poor contact with the collector track surface 64 which may otherwise result from no wearing (wiping action) and at the same time not create off-center. contacting surfaces that would cause a rotation force component to be transmitted to the brush. Also, the plane 16 makes an angle of slightly greater than with respect to the plane 15. This is intended to aid in retaining the longitudinal axis of the spring 70 stable while permitting the spring to expand and compress without rubbing against the back surface 16.
' Viewing FIGS. 9 and 10, the simplicity of assembling the apparatus can be appreciated. First, the stator 30 is assembled as previously discussed. That is, the leads 46, 47 and 48 are positioned and secured in place by the epoxy 66.. The. resistance element 60 is then positioned over the epoxy and the epoxy cured. Then the leads are soldered to the respective pads 63 and 65. Dipping into a p solder'bath has been found to be the most efiicient means of soldering. Obviously, solder stops may be used during the dipping process to maintain the solder only to the desired areas of the terminals 63 and 65. When these steps have been accomplished, the stator 30 appears as in FIG. 8. The spring 70 and ball 71 are then positioned in the cavity 10. The O-ring 9 is then. placed within the recess of the casing 2 and the rotor assembly 4 slid into position until the step 6 engages the O-ring 9 and the step 7 protrudes through the opening 3. Then the brush 75 is set within the rotor cavity 10 in the proper location. The stator 30 is then slid within the casing 2 until the step 36 engages the end ofthe casing 2. At thispoint, the brush feet 80 and 81 are in engagement with the contact surfaces 62 and 64. Completing the assembly, the casing 2, if metallic, is crimped over the flattened edge surfaces 37.
' Once assembled, as the rotor 4 isrotated, for example by a tool inserted within the slot 6, the brush 77 bridging the resistance track 62 and the collector track 64 rotates varying the resistance between the pad 63 and the pad 65. Rotation is realized in either rotational direction and continues until the stop 12 on the rotor 4 engages the stop tip 42 on the positioning ear 38.
It may be noted that the leads 46, 47 and 48 may be positioned to properly accommodate the grid patterns of standard printed circuit boards. At the present time, the standard grid pattern has holes spaced apart in multiples of 0.025 inch. The above-described potentiometer is presently being constructed with the outlines of the leads forming an isosceles triangle. The linear distance between the leads 46 and 47 is 0.200 inch with the lead 48 equally spaced from the leads 46 and 47 with the vertical distance being 0.100 inch.
It should also be appreciated that the present invention provides a structure which is small in size while being easy to assemble. Also, the demensional tolerances, even though there is small size, may be relieved. The economic advantages realized by these features is obvious. Also, the various components of the casing, rotor and stator are in general non-oriented so that little assembly time is spent in positioning the various components with relationship to one another.
It should be fully appreciated that though the preceding detailed discussion has been limited primarily to a potentiometer component, the invention is by no means so limited. For example, a switch may be realized by making one contact surface of highly conductive material and the other of at least two sections with one section being of highly conductive material and the other of insulative material. Thus, the brush can rotate between bridging two conductive surfaces (on position) and bridging a conductive and insulative surface (off position). Furthermore, a capacitive element could be realized by varying the dielectric value between the terminals as the rotor rotates.
I claim:
1. An adjustable electronic component comprising, in combination:
a cup-shaped casing having a circular recess therein;
a circular rotor having a diameter slightly less than the diameter of said recess positioned within the circular recess and rotational therein with the axis of rotation coincident with the longitudinal axis of the recess, the rotor having a cavity which cavity opens to the front face of the rotor, said cavity having a first top surface positively sloped with respect to the axis of rotation towards the front of said cavity;
a stationary base positioned With in the circular recess and in alignment with the rotor, the stationary base supporting a plurality of individual spaced apart electrically conductiveleads each having a shank portion emerging and extending outward from the base, the base further supporting a plurality of contact surfaces radially spaced apart in insulative relationship with one another, at least two of said contact surfaces electrically engaging the internal end of a conductive lead;
an electrically conductive brush member having a front surface facing the stationary base and a back surface, said front surface carrying spaced apart foot contacts with the distance between two of said foot contacts coinciding with the radial distance between two of said contact surfaces, one of said foot contacts making continuous wiping contact with one of said contact surfaces, said back surface of the brush extending at least in part within the cavity;
a compressible resilient member positioned within said cavity;
a spherical member simultaneously engaging one end of the compressible resilient member, the top surface of said cavity and the back surface of the brush, the spherical member simultaneously maintaining the resilient member under compression and urging the foot contacts of the brush member towards said contact surfaces whereby the brush member is maintained in locked position within said cavity and rotatable with the rotor, and
means for adjusting the rotational position of the rotor within the casing.
2. The adjustable electronic component of claim 1, in which the electrically conductive brush member has an inclined back surface, with the angle of inclination opposing that of said first top surface of said cavity and sloping towards the back of said cavity.
3. The adjustable electronic component of claim 2 in which the back surface of the brush member is substantial ly V-shaped with two planes merging towards a common apex and with the spherical member contacting each plane of said back surface.
4. The adjustable electronic component of claim 1 in which the cavity includes a second top surface substantially parallel with the axis of rotation, the back edge of said second top surface joining the front edge of said first top surface.
5. The adjustable electronic component of claim 1 in which the first top surface is substantially V-shaped with two planes merging towards a common apex which apex is positively sloped with respect to the axis of rotation towards the front of said cavity.
6. The adjustable electronic component of claim 1 in which the first top surface is substantially V-shaped with two planes merging towards a common apex which apex is positively sloped with respect to the axis of rotation towards the front of said cavity, said spherical member contacting each plane of said first top surface; and
said cavity includes a second top surface of substantially V-shape with two planes merging towards a common apex, the apex of said second top surface being substantially parallel with the axis of rotation and the back edge of said second top surface joining the front edge of said first top surface.
7. The adjustable electronic component of claim 6 in which the electrically conductive brush member has a back surface of substantially V-shape with two planes merging towards a common apex and the spherical member contacting each plane of said back surface, said planes of said back surface of the brush being inclined at an angle opposing that of said first top surface of said cavity and sloping towards the back of said cavity, said brush further carrying a top surface of substantially V-shape for locking engagement with said second top surface of said cavity.
8. The adjustable electronic component of claim 1 in which the compressible resilient member is a low load rate spring member having a relatively constant force of expansion while urging the spherical member along the first top surface.
9. The adjustable electronic component of claim 8 in which the compressible resilient member is a low load rate helical spring having multiple turns, said spring being positioned within said cavity with the longitudinal axis of the spring substantially normal to the axis of rotation and with one longitudinal end supported by a bottom surface of said cavity which bottom surface is substatnially normal to the longitudinal axis of the spring.
10. The adjustable electronic component of claim 7 in which the compressible resilient member is a low load rate helical spring having multiple turns, said spring being positioned within said cavity with the longitudinal axis of the spirng substantially normal to the axis of rotation and with one longitudinal end supported by a bottom surface of said cavity which bottom surface is substantially normal to the longitudinal axis of the spring, said spring having a relatively constant force of expansion while urging the spherical member along the first top surface.
11. The adjustable electronic component of claim 10 in which said cavity includes a back surface joining the bottom edge of said first top surface and the edge of the 9- back surface, the bottom surface and back surface of the cavity joining at an angle greater than ninety degrees.
12. An adjustable electrical resistance component comprising, in combination:
a cup-shaped casing having a circular recess therein;
a circular rotor having a diameter slightly less than the diameter of said recess positioned within the circular recess and rotational therein with the axis of rotation coincident with the longitudinal axis of the recess, the rotor having a cavity which cavity opens on the front face of the rotor, said cavity having a bottom surface plane radially spaced from the axis of rotation and a first top surface positively sloped with respect to theaxis of rotation towards the front of said cavity;
a stationary base positioned within the circular recess and in alignment with the rotor, the stationary base supporting a plurality of individual spaced and apart electrically conductive leads each having a shank portion emerging and extending outward from the base, the base further supporting a collector track and aresistance track radially spaced apartin insulative relationship with one another, said collector track and said resistance track being concentric and facing said cavity, said collector track electrically engaging the internalend of one of said conductive leads and said resistance track electrically engaging the internal'end of at least one of said conductive leads; i
an electrically conductive brush member having a front plane facing the stationary base and a back plane, said front plane carrying spaced apart foot contacts with one foot contact making wiping engagement with said collector track and another foot contact making wiping engagement with said resistance track, said back plane of the brush extending at least in part within the cavity;
a compressible resilient member positioned within said cavity;
a spherical member simultaneously engaging one end of the resilient member, the first top surface of said cavity and the back surface of the brush member, the spherical member simultaneously maintaining the resilient member under compression and urging the foot contacts of the brush member towards their associate-d resistance and collector tracks; and
means for adjusting the rotational position of the rotor within the casing. v
13. The variable electrical resistance component of claim 12 inwhich the electrically conductive brush member has a substantially V"-shaped back surface inclined toward the back of the cavity opposing the angle of in-- clination of said first top surface.
14. The variable (electrical resistance component of claim 12 in which the brush member has a top surface and the cavity carries a second top surface, said top surface of the brush member and the second top surface of the cavity substantially coinciding in contour; whereby the spherical member urges said top surface into locking engagement.
15. The variable electrical resistance component of claim 14 in which the first top surface of the cavity is substantially V- shaped with two planes merging towards a common apex which apex is positively sloped with respect to the axis of rotation towards the front of said cavity;
the second top surface is substantially V-shaped with two planes merging towards a common apex, the apex of said second top surface being parallel to the rotational axis and the back edge of said second top surface being common to the front edge of said first top surface;
the top surface of the brush member being of substantially V-shape for locking engagement with said second top surface; whereby the brush member can 10 travel within said cavity along the apex of said second top surface and said spherical member can travel along said top surface; and the compressible resilient member is a low load rate spring member having an axis of expansion normal to the axis of rotation and having a relatively constant force of expansion while urging the spherical member along the first top surface.
16. The variable electrical resistance component of claim 17 in which said cavity has a back surface inter mediate said bottomvsurface and said first top surface, the back surface joining said bottom surface at an angle at least slightly greater than ninety degrees.
1 19. The variable electrical resistance component of claim 15 in which said resistor track and collector track are'in the form of afilm supported by a planar substrate; theresistor track and collector track each carrying termination pads extendingto the peripheral edge of said planar substrate and electrically engaging the internal end of respective conductive leads.
' 20. The variable electrical resistance component of claim 19 in which the supporting base forms a well flanked by supporting ledges of substantially equal height,
said ledges supporting said planar substrate; 7
said terminal leads extending along said well with the internal ends advancing out of said well adjacent the periphery of said substrate and'a respective termination pad.
21. The variable electrical resistance component of claim 20 in which the planar substrate is in the form of a rectangle.
22. An adjustable electronic component comprising in combination:
c a casing;
a brush actuator positioned within the casing and movable relative thereto, said actuator having a cavity which cavity opens to the front face thereof, said cavity having a top surface portion sloped towards the front of said cavity;
a stationary base positioned'to enclose the casing, the stationary base supporting a plurality of individual spaced apart electrically conductive leads each having a shank portion emerging and extending outward from the-base, the base further supporting a plurality of contact surfaces spaced apart in insulative relationship with one another, at least two of 'said contact surfaces electrically engaging the internal end of a conductive lead; i an electrically conductive brush member having a front surface facing the stationary base and a back surface,
said front surface carrying spaced apart foot contacts withthe distance between two of said foot contacts coinciding with the distance between two of said contact surfaces, one of said foot contacts making continuous wiping contact with one of said contact surfaces, said back surface of the brush extending at least in part within the cavity;
a compressible resilient member positioned within said cavity; a spherical member simultaneously engaging one end i of the compressible resilient member, the top surface portion of said cavity and the back surface of the brush, the spherical member simultaneously maintaining the resilient member under compression and 1 1 urging the foot contacts of the brush member towards said contact surfaces whereby the brush member is maintained in locked position within said cavity and movable with said actuator; and
means for adjusting the position of the actuator within the casing.
23. The adjustable electronic component of claim 22, in which the electrically conductive brush member has an inclined back surface, with the angle of inclination opposing that of said first top surface of said cavity and sloping towards the back of said cavity.
24. The adjustable electronic component of claim 22 in which the first top surface portion is substantially V- s'haped with two planes merging towards a common apex which apex is sloped towards the front of said cavity, said spherical member contacting each plane of said first top surface; and
said cavity includes a second top surface portion of substantially V-shape with two planes merging towards a common apex, the apex of said second top surface being substantially parallel with the back edge of said second top surface portion joining the front edge of said first top surface.
25. The adjustable electronic component of claim 24 in which the electrically conductive brush member has a back surface of substantially V-shape with two planes merging towards a common apex and the spherical member contacting each plane of said back surface, said planes of said back surface of the brush being inclined at an angle opposing that of said first top surface of said cavity and sloping towards the back of said cavity, said brush further carrying a top surface of substantially V-shape for locking engagement with said second top surface of said cavity.
26. The adjustable electronic component of claim 22 in which the compressible resilient member is a low load rate spring member having a relatively constant force of expansion while urging the spherical member along the first top surface 27. The adjustable electronic component of claim 26 in which the compressible resilient member is a low load rate helical spring having multiple turns, said spring being positioned within said cavity with the longitudinal axis of the spring substantially normal to the axis of rotation and with one longituidnal end supported by a bottom surface of said cavity which bottom surface is substantially normal to the longitudinal axis of the spring.
218. The adjustable electronic component of claim 24 in which said cavity includes a back surface joining the bottom edge of said first top surface portion and the edge of the back surface, the bottom surface and back surface of the cavity joining at an angle greater than ninety degrees.
29. An adjustable electrical resistance component comprising, in combination:
-a casing;
a brush actuator positioned within the casing and movable relative thereto, said actuator having a cavity which cavity opens to the front face thereof, said cavity having a bottom surface plane radially spaced from the axis of rotation and a top surface portion positively sloped with respect to the axis of rotation towards the front of said cavity;
a stationary base positioned to enclose the casing, the stationary base supporting a plurality of individual spaced apart electrically conductive leads each having a shank portion emerging and extending outward from the base, the base further supporting a collector track and a resistance track spaced apart in insulative relationship with one another, said collector track and said resistance track being parallel and facing said cavity, said collector track electrically engaging the internal end of one of said conducive leads and said resistance track electrically engaging the internal end of at least one of said conductive leads;
an electrically conductive brush member having a front plane facing the stationary base and a back plane, said front plane carrying spaced apart foot contacts with one foot contact making wiping engagement with said collector track and another foot contact making wiping engagement with said resistance track, said back plane of the brush extending at least in part within the cavity;
a compressible resilient member positioned within said cavity;
a spherical member simultaneously engaging one end of the resilient member, the top surface portion of said cavity and the back surface of the brush member, the spherical member simultaneously maintaining the resilient member under compression and urging the foot contacts of the brush member towards their associated resistance and collector tracks; and
means for adjusting the position of the actuator within the casing.
30. The variable electrical resistance component of claim 29 in which the compressible resilient member is a low load rate helical spring of long length and a plurality of turns, said helical spring having one end cupping the spherical member and the other end supported by said bottom surface of said cavity.
References Cited UNITED STATES PATENTS 3,013,129 12/1961 Root ZOO-11.23 X
ROBERT S. MACON, Primary Examiner.
H. HOHAUSER, Assistant Examiner.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,350,673 October 31, 1967 Robert w. Spaude It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Column 1, line "44 for "engaegment" read engagement column 4, line 34, for"protroude" read protrude column 5, line 21, for "mumps" read bumps column 9, line 10, for "on" read to line 18, strike out "and; column 10, line 3, after "said" insert first column 11, line 45, for "longituidnal" read longitudinal Signedand sealed' this 31st day of December 1968.
(SEAL) Attest:
EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.
Attesting Officer

Claims (1)

1. AN ADJUSTABLE ELECTRONIC COMPONENT COMPRISING, IN COMBINATION: A CUP-SHAPED CASING HAVING A CIRCULAR RECESS THEREIN; A CIRCULAR ROTOR HAVING A DIAMETER SLIGHTLY LESS THAN THE DIAMETER OF SAID RECESS POSITIONED WITH THE CIRCULAR RECESS AND ROTATIONAL THEREIN WITH THE AXIS OF ROTATION COINCIDENT WITH THE LONGITUDINAL AXIS OF THE RECESS, THE ROTOR HAVING A CAVITY WHICH CAVITY OPENS TO THE FRONT FACE OF THE ROTOR, SAID CAVITY HAVING A FIRST TOP SURFACE POSITIVELY SLOPED WITH RESPECT TO THE AXIS OF ROTATION TOWARDS THE FRONT OF SAID CAVITY; A STATIONARY BASE POSITIONED WITH IN THE CIRCULAR RECESS AND IN ALIGNMENT WITH THE ROTOR, THE STATIONARY BASE SUPPORTING A PLURALITY OF INDIVIDUAL SPACED APART ELECTRICALLY CONDUCTIVE LEADS EACH HAVING A SHANK PORTION EMERGING AND EXTENDING OUTWARD FROM THE BASE, THE BASE FURTHER SUPPORTING A PLURALITY OF CONTACT SURFACES RADIALLY SPACED APART IN INSULATIVE RELATIONSHIP WITH ONE ANOTHER, AT LEAST TWO OF SAID CONTACT SURFACES ELECTRICALLY ENGAGING THE INTERNAL END OF A CONDUCTIVE LEAD; AN ELECTRICALLY CONDUCTIVE BRUSH MEMBER HAVING A FRONT SURFACE FACING THE STATIONARY BASE AND A BACK SURFACE, SAID FRONT SURFACE CARRYING SPACED APART FOOT CONTACTS WITH THE DISTANCE BETWEEN TWO OF SAID FOOT CONTACTS COINCIDING WITH THE RADIAL DISTANCE BETWEEN TWO OF SAID CONTACT SURFACES, ONE OF SAID FOOT CONTACTS MAKING CONTINUOUS WIPING CONTACT WITH ONE OF SAID CONTACT SURFACES, SAID BACK SURFACE OF THE BRUSH EXTENDING AT LEAST IN PART WITHIN THE CAVITY; A COMPRESSIBLE RESILIENT MEMBER POSITIONED WITHIN SAID CAVITY; A SPHERICAL MEMBER SIMULTANEOUSLY ENGAGING ONE END OF THE COMPRESSIBLE RESILIENT MEMBER, THE TOP SURFACE OF SAID CAVITY AND THE BACK SURFACE OF THE BRUSH, THE SPHERICAL MEMBER SIMULTANEOUSLY MAINTAINING THE RESILIENT MEMBER UNDER COMPRESSION AND URGING THE FOOT CONTACTS OF THE BRUSH MEMBER TOWARDS SAID CONTACT SURFACES WHEREBY THE BRUSH MEMBER IS MAINTAINED IN LOCKED POSITION WITHIN SAID CAVITY AND ROTATABLE WITH THE ROTOR, AND MEANS FOR ADJUSTING THE ROTATIONAL POSITION OF THE ROTOR WITHIN THE CASING.
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3445802A (en) * 1967-08-16 1969-05-20 Allen Bradley Co Adjustable electronic component
US3533043A (en) * 1968-11-21 1970-10-06 Allen Bradley Co Adjustable electronic component
US3601743A (en) * 1969-10-01 1971-08-24 Electra Midland Corp Miniaturized single turn potentiometer with hermetically sealed rotor and substrate
US3679847A (en) * 1971-08-26 1972-07-25 Gen Motors Corp Three position pivotal switch with improved spring biased joystick actuator and contact
US3808384A (en) * 1971-06-01 1974-04-30 Texas Instruments Inc Pushbutton keyboard system
US3839785A (en) * 1971-06-01 1974-10-08 Texas Instruments Inc Pushbutton keyboard system
US4121188A (en) * 1975-12-19 1978-10-17 North American Philips Corporation Closed frame single turn potentiometer with helical coil spring wiper adjustable through substrate
US4609793A (en) * 1983-12-13 1986-09-02 Itt Industries, Inc. Electrical slide switching device
US4621250A (en) * 1984-02-28 1986-11-04 Renix Electronique Rotary potentiometer, particularly for measuring angular position
US5039974A (en) * 1990-03-19 1991-08-13 Ericsson Ge Mobile Communications Inc. Protective cap for rotatably-adjustable electronic components

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3013129A (en) * 1958-02-28 1961-12-12 Bendix Corp Electrical apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3013129A (en) * 1958-02-28 1961-12-12 Bendix Corp Electrical apparatus

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3445802A (en) * 1967-08-16 1969-05-20 Allen Bradley Co Adjustable electronic component
US3533043A (en) * 1968-11-21 1970-10-06 Allen Bradley Co Adjustable electronic component
US3601743A (en) * 1969-10-01 1971-08-24 Electra Midland Corp Miniaturized single turn potentiometer with hermetically sealed rotor and substrate
US3808384A (en) * 1971-06-01 1974-04-30 Texas Instruments Inc Pushbutton keyboard system
US3839785A (en) * 1971-06-01 1974-10-08 Texas Instruments Inc Pushbutton keyboard system
US3679847A (en) * 1971-08-26 1972-07-25 Gen Motors Corp Three position pivotal switch with improved spring biased joystick actuator and contact
US4121188A (en) * 1975-12-19 1978-10-17 North American Philips Corporation Closed frame single turn potentiometer with helical coil spring wiper adjustable through substrate
US4609793A (en) * 1983-12-13 1986-09-02 Itt Industries, Inc. Electrical slide switching device
US4621250A (en) * 1984-02-28 1986-11-04 Renix Electronique Rotary potentiometer, particularly for measuring angular position
US5039974A (en) * 1990-03-19 1991-08-13 Ericsson Ge Mobile Communications Inc. Protective cap for rotatably-adjustable electronic components

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