US2717943A

US2717943A - Variable resistor with improved terminal

Info

Publication number: US2717943A
Application number: US403164A
Authority: US
Inventors: Arthur M Daily; Joseph G Veatch
Original assignee: CHICAGO TELEPHONE SUPPLY CORP
Current assignee: CHICAGO TELEPHONE SUPPLY Corp
Priority date: 1954-01-11
Filing date: 1954-01-11
Publication date: 1955-09-13
Anticipated expiration: 1972-09-13

Description

Sept. 13, 1955 A. M. DAILY ET AL VARIABLE RESISTOR WITH IMPROVED TERMINAL Filed Jan. 11, 1954 United States Patent VARIABLE RESISTOR WITH IMPROVED TERMINAL Arthur M. Daily, Edwardshurg, Mich, and Joseph G. Veatch, Elkhart, Ind., assignors to Chicago Telephone gupply Corporation, Elkhart, Ind., a corporation of Kin iana Application January 11, 1954, Serial No. 403,164-

1 Claim. (Cl. Mil-55) This invention relates broadly to variable electrical resistors or volume controls of the type used in radio and television apparatus and refers more particularly to the terminals for the resistance elements of such controls.

The primary purpose of this invention is to provide an improved terminal for such variable resistors which is not only better suited to mechanized or automatic assembly of the control, but also better adapts the control to use with printed circuitry.

To this end it is more specifically an object of this invention to provide a terminal for the purpose described which is characterized by the fact that it is essentially a cylindrical pin or stem having one end portion thereof received in and passing through aligned holes in the insulated base of the control and the adjacent portion of the resistance element, and flanges integral with the pin or stem between which the overlying portions of the base and resistance element are clamped.

Still another object of this invention is to provide an improved terminal of the character described which is so designed that the heat imparted thereto during the soldering operation by which a lead is soldered to the terminal is effectively and quickly dissipated to assure against loosening of the terminal by the contending forces of expansion and contraction which might otherwise be set up in the base and terminal.

Still another object of this invention is to provide an improved terminal of the character described which is more easily mounted in position and which when mounted is more rigidly supported in a definite position than is the case with the conventional stamped and formed sheet metal terminals heretofore widely used in variable resistors.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claim, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claim.

The accompanying drawing illustrates two complete examples of the physical embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a side elevational view of a variable resistor embodying this invention and having parts thereof broken away and in section to better illustrate structural details;

Figure 2 is a perspective view of the variable resistor shown in Figure 1, illustrating the same principally from the back end thereof;

Figure 3 is a perspective view of one form of the terminal per se illustrating the same prior to its assembly in the control;

Figure 4 is an enlarged detail sectional view through the mounted end of the terminal;

Figure 5 is a perspective view similar to Figure 3 but 2 ,2 E1943 Patented Sept. 13, 1955 illustrating another form of terminal embodying this invention; and

Figure 6 is a fragmentary detail sectional view through a portion of a variable resistor base and its resistance element illustrating the terminal of Figure 5 mounted in position thereon.

Referring now particularly to the accompanying drawing, the numeral 5 designates generally a variable resistor of the type having a fiat base 6 of insulating material and a fiat split ringshaped resistance element 7 on the inner face of the base. The resistance element 7 is adapted to be traversed by a contactor which forms part of the rotating assembly of the control. This assembly, which is of conventional construction and hence not shown, is inside the housing of the control formed jointly by the base 6 and a cup-shaped stamped metal cover or casing 8 and is driven by a control shaft 9 which passes through the base 6.

The rotating assembly of the control in addition to the contactor which traverses the resistance element also has a contactor riding upon a collector ring (also not shown) which generally is provided with an integral terminal iii which projects perpendicularly straight out from the front of the base or more correctly from a radially outwardly extending terminal support 11 integral with the base.

The end portions 12 of the resistance element overlie the terminal support Ill and are secured thereto by means of the terminals 1?; of this invention. While the use of the terminals of the resistance element to secure the element in place on the base is not new in itself, the way in which this is done with the terminal 13 is new and has many advantages over the prior art. Thus for instance, by virtue of their construction and mounting the terminals 15 have greater rigidity than heretofore, and assurance against impairment of good electrical connection between the terminal and the resistance element is increased.

Another very important advantage of the present invention lies in the fact that the terminals 13 are far better suited to mechanized assembly and also by virtue of their added rigidity better adapt the control to use with printed circuitry.

in that form of the invention illustrated in Figures 1 to 4, inclusive, the terminals 13, which are of course identical in all respects, consist essentially of a cylindrical pin or stem having an inner end portion 14 and an outer end portion 15 with a flange 16 integral with and separating these two end portions. The flange 16 is undercut as at 17 for a purpose to be later described, and the extremity of the end portion 14 has an axial well or cavity 18 extending axially thereinto. The end portion 14 fits snugly in aligned holes in the base and the adjacent end portion 12 of the resistance element with the flat underside 19 of the flange 16 bearing against the outer face of the base and more specifically its terminal support 11.

By virtue of the undercut formation of the flange the end portion 14 of the terminal may have a close fit in the holes in which it is received without interfering with the engagement of the fiat underside 19 of the flange with the face of the base against which it abuts.

After the terminal has been thus assembled, the hollow extremity of the stern portion 14 is rolled over or riveted .to form a second flange 2i? which overlies the surface of the resistance element and has good electrical connec tion therewith. The portions of the resistance element and base immediately adjacent to the aligned holes in which the terminal is received are thus clamped between the two flanges, and to improve the electrical connection between the terminal and the resistance element the flange 29 preferably has a plurality of radial indentations 21 formed therein during the clinching or riveting operation, which indentations as best shown in Figure 4, result in slight radially extending ridges 22 projecting from the underside of the flange Z9 and biting into the adjacent surface of the resistance element.

The terminal 13 is thus rigidly and firmly mounted upon the base of the control instrument and when thus positioned projects straight out from the front of the base in parallel relationship to the axis of the control shaft 9. Accordingly, when the control is mounted upon a panel 24 having printed wiring (not shown) on its front face, the terminals 13 as well as the center terminal 10 will project through appropriately located holes in the panel, to enable the terminals to be soldered in any suitable manner to their respective leads.

The heat imparted to the terminals 13 during the soldering operation is quickly dissipated by the relatively large area of contact between the flange 16 and the base 6 and as a result the effect of contending forces of expan sion and contraction is minimized so that there is less likelihood of the terminal being loosened during the soldering operation.

Attention is directed to the fact that the flange 16 has a diameter approximately twice that of the stern portion 15 and that it has substantial thickness so as to have adequate strength to withstand the riveting or clinching operation by which the terminal is secured in place.

in that embodiment of the invention illustrated in Figures 5 and the preformed flange 16', which like the flange 16 is undercut as at 17', is on the extreme end of the mounting portion 34 so as to overlie the resistance element rather than the front face of the base. Also,

in this case the mounting portion 14 of the terminal is larger in diameter than its outer end portion 15 which provides the terminal per se so as to form a step or shoulder 25 spaced from the fiat underside 19' of the flange 16' a distance suflicient to enable the attaching end portion 14' to reach all the Way through the aligned holes in the resistance element and base. During assembly the shoulder portion 25 is upset or swaged down over the adjacent face of the base to form the second flange 20.

As in the previously described embodiment of the invention, the terminal construction of Figures 5 and 6 also I has the advantage of rapidly dissipating the heat imparted to the terminal during the soldering operation over a relatively wide area but in this case, of course, the flange 16 carries this heat into the resistance element rather than directly into the base.

From the foregoing description taken in connection with the accompanying drawing it will be readily apparent to those skilled in the art that this invention provides an improved terminal for variable resistors wherein the resistance element is secured in position on its base by the attachment of the terminal, and that the terminal of this invention has the advantage of lending itself well to mechanized assembly of the control and of better adapting the control to use with printed circuitry.

What we claim as our invention is:

in a variable resistor: a flat base of insulating material; a resistance element on the rear face of the base; a rotatable contacto. assembly behind the base; a control shaft for the contactor assembly extending therefrom perpendicularly to the base and projecting through and beyond the front face of the base; and rigid terminals for the resistance elem nt secured to the base and projecting perpen" arly t'o ardly therefrom in parallel relation to t sh ft to pass through a panel upon which the resistor is mo ed with its shaft projecting through the panel, t. e pro, ..tion of the terminals through the panel ding the resistor against rotary motion about the shaft axis and providing for the connection of the resistance element to circuit leads printed on the front face of the panel, said terminals each comprising a still stem having one end portion thereof received in aligned holes in the base and the adjacent end portion of the resistance element and its other end portion extending a substantial distance out from the overlying base and resistance element, nd flanges on the stern overlying the outer surface porti as of the base and the resistance element boundthe edges of the holes therein and between which the e and resistance element are clamped, to thereby effect good electrical connection between the terminals and the resistance element and also rigidly mount the erminal with its other end portion projecting perpena arly outwardly from the base; one of said flanges being a preformed integral part of the stem, and the other flange being a part of the stern which has been deformed from its original shape.

References Cited in the file of this patent UiJtTED STATES PATENTS 1,874,594 Olson Aug. 30, 1932 2,157,428 Obszarny May 9, 1939 2,169,594 Schellenger Aug. 15, 1939 FOREIGN PATENTS 1,028,657 France Nov. 30, 1950