US3124774A

US3124774A - Lafont

Info

Publication number: US3124774A
Authority: US
Priority date: 1961-07-05
Filing date: 1962-07-05
Publication date: 1964-03-10
Anticipated expiration: 1981-03-10
Also published as: FR1301409A; GB947984A

Description

March 5 M. LAFONT 3,124,774

PRECISION.POTENTIOMETER Filed July 5, 1962 United States Patent 3,124,774 PRECESION POTENTIOMETER Michel Lafont, Paris, France, assignor to Les Laboratoires de Physique Appliquee, Paris, France, a corporation Filed July 5, 1962, Ser. No. 207,610 Claims priority, application France July 5, 1961 3 Claims. (Cl. 338162) The present invention relates generally to electric precision potentiometers and, more particularly, to coils of otentiometers of the toroidal type having their sliding contact efiecting a continuous rotation, with no provision for a stop member; more particularly, it relates to the electrical insulation of the ends of said coil at their junction point.

In this class of potentiometer-s, the insulation of the ends of the coil is commonly obtained by separating the two end portions of the toroidal support carrying the coil by means of an isolating wedge inserted in the junction plane thereof. This method is however rather difficult to achieve in practice since the upper portion of the isolating wedge used must in this case be exactly on a level with the turns of the winding, so as to allow the slider to pass without being interfered with.

According to the invention, the two end portions of the toroidal-shaped support of the potentiometer are directly joined together and a few of the end turns of the coil are cutout over a portion of their length with which the slider does not come into contact, said turns being located on both sides of the junction plane of said end p ortions and covering up a length of said support which is slightly larger than the width of the contact area of the slider.

Preferably, said turns are cut out by causing a substantially radial cavity or notch to be formed in the toroidal support, accommodating therein an isolating wedge which serves to accurately position the toroidal support on its carrier element.

The invention will be best understood from the following description and appended drawing, the single figure of which illustrates, by way of an unlimitative example, on a greatly enlarged scale, the two ends of a toroidal winding, in which a few of the end turns of the winding have been cut out.

Referring to the drawing, a toroidal support 1 is shown having thereon a winding 2, a sliding contact 3 and two terminal voltage taps 4 and 5. Said taps may be for instance keyed between an isolating wedge 6 and a. carrier portion 7 of the toroidal support.

The various components described being well known in the art, have been illustrated in the drawing in a very diagrammatic manner only, since they may assume any desired shapes.

According to the invention, a substantially radially extending cavity or recess 8 has been formed in the toroidal support 1. Said recess is located about the junction plane 9 of the two

end pieces

10 and 11 of the toroidal support and is arranged to sever three turns of the winding (although this number is in no way limitative) over a given portion of their length. Said turns normally adhere to the support and cannot therefore get loose from member 1; they simply play a mechanical part which consists in ensuring the passage of the sliding contact 3.

The width of the dead area thus formed may obviously 2 be readily adjusted, which is a highly desirable feature of this invention. It must however remain greater than the contact area of the slider so as to avoid a short-circuit at the passage thereof, and smaller than the distance separating the

terminal supply contacts

4 and 5 of the p otentiometer.

Said recess in the support may be for instance formed by milling the already manufactured toroidal support members.

As noted the recess serves to accommodate the isolating wedge 6, thus ensuring an accurate positioning of the toroidal member on carrier element 7.

It is to be understood that various modifications may be brought to the embodiment described and illustrated, without departing from the spirit and scope of the invention.

What is claimed is:

1. *In a potentiometer of the continuous rotation type: an electrical resistance coil having a plurality of turns; a toroidal insulating member for supporting said coil; two terminals electrically connected to said coil at two respective points thereof; said coil having a first portion having turns which are cut out over a part of their length and a second portion having complete turns, said first portion being located in the space between said two points, the cut-out turns individually adhering on said insulating member, whereas the complete turns are spirally wound on said insulating member; a contact member in sliding relationship with each of said cut-out and complete turns successively, whereby an electrical connection is established between said contact member and said complete turns, while the cut-out turns co-operate with said contact member for ensuring the mechanical passage thereof.

2. In a potentiometer of the continuous rotation type: an electrical resistance coil having a plurality of turns; a toroidal insulating member for supporting said coil, said insulating member having two end portions joined together along a junction plane; two terminals electrically connected to said coil at two respective points thereof, said coil having a first portion having turns which are cut out over a part of their length and a second portion having complete turns, said first portion being located in the space between said two points, the cut-out turns individually adhering to said insulating member, whereas the complete turns are spirally wound on said insulating member; a contact member in sliding relationship with each of said cut-out and complete turns successively, whereby an electrical connection is established between said contact member and said complete turns, while the cut-out turns cooperate with said contact member for ensuring the mechanical passage thereof, said first portion substantially being symmetrically arranged with respect to said junction plane, said toroidal member having a radially extending recess located along said first portion.

3. In a potentiometer of the continuous rotation type: an electrical resistance coil having a plurality of turns, a toroidal insulating member for supporting said coil, said insulating member having two end portions joined together along a junction plane; two terminals electrically connected to said coil at two respective points thereof; said coil having a first portion having turns which are cut out over a part of their length and a second portion having complete turns, said first portion being located in the space between said two points, the cut-out turns individually adhering to said insulating member, whereas the 4 complete turns are spirally wound on said insulating mern- References Cited in the file of this patent her; a contact member in sliding relationship with each UNITED STATES PATENTS of 58rd. cut-out and complete tur-ns successively, whereby n electrical connection is established between said con- 6 wzlmwnght 19:25 tact member and said complete turns, While the out-out 5 4' Elliott Sept 8 turn cooperate with said conta ot member for ensuring 2927293 D1011 1960 the mechanical passage thereof, said first portion sub- FOREIGN PATENTS stantially being symmetrically arranged with respect t 1,103,756 France June 1 1955 said junction plane, said toroidal member having a radial- 1y extending recess located along said first portion; an 10 isolating wedge being accommodated in said recess.

Notice of Adverse Decision in Interference In Interference No. 94,313 involving Patent No. 3,124,774, M. Lafont, PRECI'SI ON POTENTI-OMETER, final judgment adverse to the patentee Was rendered Feb. 1, 1965, as to claim 1.

[Ofiioz'al Gazette March 30, 1.965.]

Notice of Adverse Decision in Interference In Interference N0. 9%,313 involving Patent No. 3,124,774, M. Lafont, PRECISION POTENTI-OMETER, final judgment adverse to the patentee was rendered Feb. 1, 1965, as to claim 1.

[Ofiicial Gazette March 30, 1.965.]

Claims

1. IN A POTENTIOMETER OF THE CONTINUOUS ROTATION TYPE: AN ELECTRICAL RESISTANCE COIL HAVING A PLURALITY OF TURNS; A TOROIDAL INSULATING MEMBER FOR SUPPORTING SAID COIL; TWO TERMINALS ELECTRICALLY CONNECTED TO SAID COIL AT TWO RESPECTIVE POINTS THEREOF; SAID COIL HAVING A FIRST PORTION HAVING TURNS WHICH ARE CUT OUT OVER A PART OF THEIR LENGTH AND A SECOND PORTION HAVING COMPLETE TURNS, SAID FIRST PORTION BEING LOCATED IN THE SPACE BETWEEN SAID TWO POINTS, THE CUT-OUT TURNS INDIVIDUALLY ADHERING ON SAID INSULATING MEMBER, WHEREAS THE COMPLETE TURNS ARE SPIRALLY WOUND ON SAID INSULATING MEMBER; A CONTACT MEMBER IN SLIDING RELATIONSHIP WITH EACH OF SAID CUT-OUT AND COMPLETE TURNS SUCCESSIVELY, WHEREBY AN ELECTRICAL CONNECTION IS ESTABLISHED BETWEEN SAID CONTACT MEMBER AND SAID COMPLETE TURNS, WHILE THE CUT-OUT TURNS TO CO-OPERATE WITH SAID CONTACT MEMBER FOR ENSURING THE MECHANICAL PASSAGE THEREOF.