US3619532A

US3619532A - Self-aligning contact for switch

Info

Publication number: US3619532A
Application number: US858742A
Authority: US
Inventors: Fritz L Lyvang
Original assignee: Electrohome Ltd
Current assignee: Electrohome Ltd
Priority date: 1969-09-17
Filing date: 1969-09-17
Publication date: 1971-11-09
Anticipated expiration: 1988-11-09

Abstract

A resilient elongated wirelike contact which is self-aligning in an aperture in a base member. The aperture is circular and has a greater diameter than the wirelike contact, so that an end portion of the latter can be inserted in the aperture, oriented in a desired direction so as to make the end portion bind angularly in the aperture, and then fixed to the base member as by soldering.

Description

O Umted States Patent [11l3,6l9,532

[72] Inventor Fritz L. Lyvang [56] References Cited I N 3: a UNITED STATES PATENTS P 2 3,388,229 6/1968 Lyvang ZOO/166.1 [22] Filed Sept. 17, 1969 3,162,721 12/1964 Rayburn.. 339/17 C X [45] Patented Nov. 9, 1971 3,177,311 4/1965 Torrico ....200/166(.1)X [73] Assignee Electrohome Limited Ontario Canada 3,260,828 7/1966 Cartier 200/166 (.1 3,287,795 11/1966 Chambers et a1. ....29/630 (D) UX 3,345,622 10/1967 Matsushita 339/17 X 3,430,019 2/1969 Krautwald et a1 200/166 1) Primary Examiner-H. 0. Jones AnorneyThomas T. Rieder [54] SELF-ALIGNING CONTACT FOR SWITCH 6 4 ABSTRACT: A resilient elongated wirelike contact which is [52] 11.8. C1 200/1661, self-aligning in an aperture in a base member. The aperture is 339/17 circular and has a greater diameter than the wirelike contact, [51 Int. Cl H0111 l/00 so that an end portion of the latter can be inserted in the aper- [50] Field of Search 6. 200/166 C, ture, oriented in a desired direction so as to make the end por- 166PC,166B,166.1,166CT;339/17,17C,17 LC; 29/626, 630 D tion bind angularly in the aperture, and then fixed to the base member as by soldering.

PATENTEUNUV 9m: 3.619.532

11 V20 1'0 FIGB l1 IP20 15 q FIG4 FRHS L-LYVAN SELF-ALIGNING CONTACT FOR SWITCH This invention relates generally to self-aligning .resilient members, and more particularly to an elongated wirelike contact element adapted to be self-aligning in an apertured plate on which a printed circuit has been imposed, especially when the direction of alignment of the contact element is highly critical with regard to its proper functioning.

The contact element of this invention finds particular application as a component in a switch adapted for use as an attenuating stop for electrical organs, although it will be readily discerned from what follows that the contact element according to this invention is capable of many applications outside of this field.

The point of departure for the present invention is the invention disclosed in U.S. Pat. No. 3,388,229, issued June I l, 1968 to the present inventor, and entitled Switch Particularly for Electronic Organs." The switch therein disclosed utilizes elongated wirelike contact elements which, in order to function properly, must be aligned in a given direction, so that the free ends of the contact elements will, of their own accord, seek to lodge in the apices of cutout terminals, due to the resilience of the contact elements. The apices of the several cutaway portions of the terminals lie in a plane containing the position of the contact elementwhen the latter is at rest. The contact element is deformed along this plane away from its at rest position, and lodged within the apex of one of the terminals. If the stress in the contact element is such that it wants to move to one side or other of the apex, rather than in the exact direction in which the apex points, then there is a risk that the contact element will not lodge in the apex of the cutaway portion of the terminal, but will rather lie somewhat to one side or other of the apex, in which latter positions there is some risk that the contact element will come into electrical contact with one of the other terminals simultaneously, which is highly undesirable.

In view of the above disadvantage of the prior art contact element, it is an object of the present invention to provide an elongated, wirelike contact element for a switch, such as that shown and described in U.S. Pat. No. 3,388,229, the contact element and the base plate being such that the contact element is self-aligning with respect to the plate, when the free end of the contact element is lodged in the apex of one of the terminals, or otheranalogous structure, such that, once the contact element has found its desired aligned position, it can be welded or soldered in place at its contact with the plate.

Accordingly, this invention provides, for use with a base member provided with a circular hole, a resilient elongated member having its one end portion of circular cross section for insertion into the circular hole, the diameter of said one end portion being smaller than the diameter of the circular hole so that said one end portion can bind angularly within the circular hole when the other end portion of the resilient elongated member is urged in a given direction, the said one end portion having a bend spaced from its extremity and adapted to engage the edge of said circular hole and restrain said one end portion from sliding further into the circular hole.

One embodiment of this invention is shown in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which:

FIG. 1 is a partly broken-away perspective view of a switch utilizing the elongated member of this invention; and

FIGS. 2, 3 and 4 are sequential elevational views of three steps in the operation of the particular switch shown in FIG. 1.

Attention is first directed to FIG. I, in which can be seen a base member 10, in the formof a plate, the base member being provided with two

holes

11 and 12. A plated-on portion 14 of a printed circuit," usually of copper, forms the bottom edge of the

circular holes

11 and 12. The base member also securely supports a first terminal 16, a second terminal 18, and a third terminal 20. The first and

third terminals

16 and 20 have V-shaped cuts in their upper edges, the

cuts forming apices

22 and 23, respectively. The second terminal 18 has a central opening 25, the upper margin of which defines an inverted V, constituting a further apex 26.

The essential component of the switch shown in FIG. 1, as far as this invention is concerned, is a resilient elongated member 28, which is preferably made from resilient wire stock such as piano wire. The elongated member 28 has an end portion 30 adapted for insertion in the circular hole 11 so that it can bind angularly therewithin as shown in FIG. 1. A bend 32 is spaced from the extremity 33 of the end portion 30, the bend being adapted to engage the upper edge 34 of the circular hole 11 to restrain the end portion 30 from sliding further into the circular hole 11. In actual practice, the frictional engagement between the end portion 30 and the edges of the circular hole 11 may be great enough that the angular binding suffices to retain the end portion 30 in the position shown in F IGS. 1 through 4, in which the bend 32 is not quite in engagement with the upper edge 34 of the circular hole II. The bend 32 thus acts as a kind of limit stop which prevents the end portion 30 from sliding beyond a certain point into the circular hole 11. The elongated member 28 has an S-configuration 36 beginning inwardly of the bend 32, and ending in an extended portion 38 which is shown in its unstressed position in broken lines in FIG. 1. It will be noted that, in its unstressed condition, the extended portion 38 is substantially rectilinear, although this is not essential to the invention.

The switch shown in FIG. 1 is in an incompleted state because (a) it is necessary to anchor the first, second and third terminals l6, l8 and 20 securely into the base member I0, by welding, glueing or other means, and (b) it is necessary to secure the end portion 30 in the circular hole 11. Prior to securing the end portion 30in the circular hole 11, however, the elongated member 28 must be correctly aligned with the

apices

22, 23 and 26 in the terminals I6, 18 and 20. This alignment is accomplished by first passing the extended portion 38 through the opening 25 in the second terminal 18, and then inserting the end portion 30 through the circular hole II to the position shown in FIG. 1 in solid lines. The angle between the end portion 30 and the extended portion 38 when the latter is in its unstressed position is such that, in order to bring the extended portion 38 down into its solid-line position of FIG. I, the S-configuration 36 of the elongated member 28 must be compressed, thereby causing the end portion 30 to bind angularly within the circular hole 11 as shown in FIG. 1. Because the hole 11 is circular, and because the end portion 30 is of circular cross section whose diameter is smaller than the diameter of the circular hole 11, the elongated member 28 will be self-aligning with respect to the apex 26 in the second terminal 18. That is to say, the end portion 30 will automatically take up a position within the circular hole 11 such that the extended portion 38, when in its unstressed condition (broken lines in FIG. 1) will lie directly above the

apices

22, 23 and 26 of the terminals.

When the end portion 30 binds angularly in the circular hole 11 as shown in FIG. 1, it is urged into contact with the printed circuit portion 14, and thus electrical contact occurs between them. It will be appreciated that the printed circuit could be located on either face of the base member 10, provided a portion of the printed circuit were arranged to define one edge or the other of the circular hole 1].

In the particular switch shown in the figures, which merely represents one of the many contexts in which the elongated member of this invention could be utilized, the extended portion 38 is made to contact one or another of the three

terminals

16, 18 and 20 by being urged downwardly at a point intermediate the S-configuration 36 at the terminals through the agency of an electrically nonconductive pad 40, which is secured to the end of an arm 42 which forms part of a mechanism (not shown) adapted to pivot the arm 42 about an axis oriented perpendicularly with respect to the solid-line position of the extended portion 38, the axis being located generally above the elongated member 28 between the ends of the latter.

Attention is now directed to FIG. 2, in which the elongated member 28 is shown to be welded into the'aperture II, the welding having taken place after the self-alignment mentioned above. The elongated member 28 is thus in permanent electrical contact with the portion 14, which is electrically connected with a wire 44 which is welded into the circular hole 12. Thus, permanent electrical contact is maintained between the wire 44 and the elongated member 28. The extended portion 38 of the elongated member 28 is entrapped within the opening 25 of the second terminal 18, and, in the absence of contact by the pad 40, resides in the apex 26 of the opening 25, as shown in FIG. 2.

As the arm 42 is pivoted in the clockwise direction (as seen in the figures) to the position shown in FIG. 3, the pad 40 comes into sliding contact with the extended portion 38, and pushes downwardly thereagainst. The downward movement of the extended portion 38 at a point midway of its ends causes the lefi-hand end of the extended portion 38 to be disengaged from the second terminal 18 and to move downwardly into the apex 22 of the first terminal 16. This situation is shown in FIG. 3, and the mechanism of which arm 42 forms a part is preferably constructed in such a way that the arm 42 has an at-rest" position in the H6. 3 situation. Thus, in FIG. 3, the wire 44 is in electrical contact with the first terminal 16.

To bring the extended portion 38 of the elongated member 28 into contact withv the third terminal 20, the arm 42 is rotated further in the clockwise direction, to bring the pad 40 to a lower position with respect to the base member 10, and thus urge the extended portion 38 closer to the surface of the base member 10. As the pad 40 moves from the FIG. 3 to the FIG. 4 position, there will come a point where the extended portion 38 simultaneously contacts the

apices

22 and 23 of the first and

third terminals

16 and 20. A slight further downward movement of the pad 40, however, will cause the left-hand end of the extended portion 38 to be levered about the apex 23 of the third terminal 20 to lift the extended portion 38 away from contact with the apex 22 of the first terminal No. Thus, the third terminal 20 acts somewhat in the manner of a fulcrum to break the contact between the extended portion 38 and the first terminal 16. Again, the arm 42 preferably has an at-rest" position in the FIG. 4 situation, whereby electrical contact between the wire 44 and the third terminal 20 is maintained.

it will be appreciated that the elongated member 28 need not be entirely of circular cross section, the only critical portion being the end portion 30 which is adapted to be lodged in the circular hole 11.

It will also be clear that the S-configuration shown at 36 in FIG. I is not absolutely essential to the invention, but merely increases the resilience of the elongated member 28 generally, and for example permits greater departure from the broken line unstressed position shown in FIG. 1 without taking the material of the elongated member above the elastic limit in the stress-strain diagram.

It will also be obvious that the base member need not be in the form of a plate, but could rather be a solid member, with a blind" hole drilled therein, in which case the insert or printed circuit would have to be located on the upper surface of the base member, with the end portion 30 of the elongated member 28 coming into contact therewith at the upper edge ofthe blind" hole.

Although the binding material for securing the end portion 30 and the terminals to the base member 10 is preferably solder, it will be appreciated that other materials may be used as well. it is preferable to use an electrically conductive material to secure the end portion 30 into the circular hole 11, although nonconductive binding material could be used for the terminals l6, l8 and 20 provided the electrical wires 46 leading to the terminals were properly anchored to the terminals beforehand.

What I claim is:

1. In combination:

a platelike base member therethrough,

a terminal fixed to the base member at a location spaced from said circular hole and definin a contact notch, an electrically conductive, resrllent e ongated member having its one end portion substantially straight with a circular cross section of smaller diameter than said circular hole, the one end portion terminating in an obtuse-angled bend and received in said circular hole with the bend adjacent the base member, the elongated member having its other end portion extending to said terminal and being resiliently stressed to lodge within said contact notch, the said other end seeking a hypothetical unstressed position in a plane normal to the base member and containing the said other end when said other end is lodged in said contact notch,

Whereby the stress in the elongated member when lodged within said contact notch causes the said one end portion to bind angularly in said circular hole.

2. The invention claimed in claim 1, in which the elongated member is a wire of uniform circular cross section, and is configured to define an Scurve extending from said obtuse-angled bend toward said terminal, then curving back toward said circular hole, then curving again in the direction of the terminal, the contact notch opening toward the base member.

3. The invention claimed in claim 1, in which the platelike base member has a printed circuit thereon of which a portion abuts said circular hole, whereby when said one end portion binds angularly in said circular hole it is urged into electrical contact with said printed circuit.

4. The invention claimed in claim 3, in which an electrically conductive binding material anchors the said one end portion in said circular hole and provides a conductive bond between said one end portion and said printed circuit.

5. The invention claimed in claim 4, in which the said binding material is solder.

6. The invention claimed in claim 4, in which the contact notch opens toward the base member, in which the said hypothetical unstressed position of the said other end is further from the base member than its stressed position lodged in said contact notch, and in which the elongated member is a wire of uniform cross section and is configured to define an S- curve extending from said obtuse-angled bend first toward said terminal, then curving back toward said circular hole, then curving back again in the direction of said terminal.

* I l l having a circular hole

Claims

1. In combination: a platelike base member having a circular hole therethrough, a terminal fixed to the base member at a location spaced from said circular hole and defining a contact notch, an electrically conductive, resilient elongated member having its one end portion substantially straight with a circular cross-section of smaller diameter than said circular hole, the one end portion terminating in an obtuse-angled bend and received in said circular hole with the bend adjacent the base member, the elongated member having its other end portion extending to said terminal and being resiliently stressed to lodge within said contact notch, the said other end seeking a hypothetical unstressed position in a plane normal to the base member and containing the said other end when said other end is lodged in said contact notch, Whereby the stress in the elongated member when lodged within said contact notch causes the said one end portion to bind angularly in said circular hole.

2. The invention claimed in claim 1, in which the elongated member is a wire of uniform circular cross-section, and is configured to define an S-curve extending from said obtuse-angled bend toward said terminal, then curving back toward said circular hole, then curving again in the direction of the terminal, the contact notch opening toward the base member.

6. The invention claimed in claim 4, in which the contact notch opens toward the base member, in which the said hypothetical unstressed position of the said other end is further from the base member than its stressed position lodged in said contact notch, and in which the elongated member is a wire of uniform cross-section and is configured to define an S-curve extending from said obtuse-angled bend first toward said terminal, then curving back toward said circular hole, then curving back again in the direction of said terminal.