US1972499A - Woven resistor - Google Patents

Description

p 1934- R. E. TARPLEY 1,972,499

WOVEN RESISTOR Filed Jan. 14. 1932 3 Sheets-Sheet 1 Sept 1934' R. E. TARPLEY 1,972,499

WOVEN RESISTOR Filed Jan. 14. 1932 3 Sheets-Sheet 2 p 1934- R. E. TARPLEY 1,972,499

WOVEN RESISTOR Filed Jan. 14. 1932 5 Sheets-Sheet 3 &

J Mwgm 13-4 flzivrne Patented Sept. 4, 1934 p I woven RESISTOR Raymond E. Tarpley, Philadelphia, Pa., assignor to Leeds & Northrup Company, Philadelphia,

Pa., a corporation of Pennsylvania Application issues 14, 1932, Serial No. 586,518

. '11 Claims. (01. 201-63) My invention relates to resistors, or resistance pl, 112 are widely separated, and for like reasons units having low or negligible inductance and cathe separation of the warp elements, the diamepacity to ensure that their time constant is low ters of the conductors C and warp elements, is

- throughout a wide range of frequencies, and to exaggerated. The weave is the ordinary or norpermit their use in both direct current and'altermal weave in which the conductor C passes alternating current measuring systems. nately over and under the warp elements.

In accordance with my invention, resistance As shown most clearly in Fig. la, with this conductor is woven on a suitable warp to reduce ype of weave, each pair of picks forms an inth a acitative effects to negligible magnitude, ductive loop about each of the wire elements, and lo the picks'of conductor lying in the warp so that these loops are cumulative, so that each wa p their inductive effects annul one another. element or thread forms the core of an inductive More specifically, the conductor is woven in solenoid. Specifically, and referring to Fig. 111, such manner that the warp elements form the picks p1 and p2 in effect, and as indicated by the cores of non-inductive solenoids, or otherwise exa ows, form loops about the warp threa S0 is pressed, the loops formed by adjacent picks passthat hey are alternately of opposite p ri ing on opposite sides of a warp element are indi- Similarly, picks p3 n P form a- S ri s of invidually inductive but cumulatively non-inductive. ductive loops about the warp elements which are Moreparticularly, in some forms of y i ve alternately of opposite polarity. As indicated in tion, adjacent picks form a bifilar winding ex- I the fi u s t l p formed about n m t 1 20 tending across the warp and encircling the warp y h Picks 2 P i of the m p l i y as he element at a selvedge edge, and in one modifloa- D formed around the Same p element by tion, these loops are cumulatively non-inductive, picks 203, p4- Similarly, v ry subsequent p r f so that all of the warp elements form the cores picks l o f m a l p wh e inductive effect is of q d ti l id cumulative with the inductive effects of the other 25 My invention also resides in resistors having loops alone the e w p em t. e locus the features of construction and arrangement formed by the Picks around each of h nde hereinafter described and claimed, For an unof the warp elements are cumulative'in their inderstanding of my invention and for an illustraotive effects. tion of several of the'forms it may take, reference Resistors so woven exhibit substantial induc- 30 is to be had to the accompanying drawings in tance, so that the time constant of such a resistor which: v I is-of substantial magnitude and for resistors of Fig. 1 illustrates the weaving pattern of a prethe same value of resistance and supposedly simiviously known type of woven resistor. lar, the time constant varied widely. It was Fig. 1a is an explanatory sketch referred to in necessary to measure the time constants of the 35 description of Fig. 1. resistors and select those best suited for alternat- Figs. 2 and 3 illustrate the weaving pattern of ing current uses, and even they introduced large two forms of improved woven resistors; while errors in phase angle measurements at higher fre- Figs. 2a, 2b, and 3a are explanatory figures. quencies, for example 10,000 cycles and upwards. I Figs. 4 to 9 inclusive illustrate various mount- In accordance with my invention, the time 4 ings for woven resistors. constant of a woven resistor can be made so low Fig. 10 illustrates the weaving pattern of still that the error introduced for widely different frea further modified form of an improved woven quencies, is negligible and for resistors of the same resistor, and Fig. 10a is an explanatory figure. resistance and type, the time constant is sub- Resistors for use with alternating current, or stantially the same and does not vary widely as 45 both direct and alternating currents, inaddition with supposedly similar resistors as heretofore to the requirements of resistors satisfactory for made. direct current measurements, should have the Referring to Fig. 2 which illustrates one of the characteristic that their efiective resistance is modified forms of weave, it is to be noted that the independent of frequency, and their reactance conductor C in the first pick passes under both 50 negligible at least for a substantial frequency the warp elements ml and 102. The remainder range; of the pick is the normal weave, and'normal weave Referring to Fig. 1, the resistance conductor is continued until the warp elements wl and 102 or wire 0 is woven on a warp comprising the warp are again reached, whereupon the conductor now elements w1, w2, etc. of suitable material, as silk passes over both of these elements. The next 55 threads. For clarity of illustration, the picks pair of picks p3 and M are woven in the normal manner, but the next pair of picks p5, 106, are similar to the first pair of picks p1, p2, that is, in the first pick of the pair, the conductor passes under two adjacent warp elements wl, 102, and in the next pick the conductor passesover the same two elements. The next pair of picks isof normal weave, the same as picks p3 and p4. The pattern is repeated with alternate pairs of picks ofnormal weave and every otherpair of picks of the modified weave.

The efiect upon the inductance of the woven resistor is apparent from Fig. 2a and by comparison with Fig. 1a. Taking the warp element w6, forexample, it is to be noted that the inductive loops formed. by the picks are alternately oi difierent polarity so that their inductive efiects annul each other, the warp element forming in efiect a non-inductive solenoid. Similarly, the warp elements w5, w4, etc., form the cores of noninductive solenoids. With this mode of weaving, however, the inductive loops about the warp element 101, at oneof the selvedge edges, arecumulative so that warp element 1 forms the core of an'inductive solenoid. However, this mode of weaving is substantial improvement over that in Fig. 1, as all of the inductive solenoids can be eliminated except one, irrespective of the number of warp elements.

' With this type of'woven resistor, the inductance is so low as to permit of its use in precision circuits such as used in measuring, through'a substantial range of frequencies, without introducing any serious error. It has also been noted -in manufacture, in resistors of this type, that the residual inductance of the resistors would be practically identical, whereas the inductance of the previously known type of woven resistor, such as exemplified in Fig. 1, would vary widely, for example, of two resistors having the same resistance and woven in accordance with Fig. 1, one would have three or four times the inductance of the other.

Referring to Fig. 2, it is pointed out that except at the selvedge edge about the warp element wl, the picks p2, p3 lie side by side in the warp, that is, both pass over warp element w2, under warp element w3, over warp element 104, etc. As the current flows through these adjacent picks inopposite directions, the picks in effect form a short, bifilar winding. Similarly, the next pair of picks p4, p5 lie side by side through the warp, both passing over 105, under 1124, over 203, etc., to form another short bifilar section. This is shown most clearlyin Fig. 2b. As the sections are bifilar, the inductive eifect of the picks forming each sec-. tion annul one another. At the end of each bifilar section, adjacent the right hand selvedge edge, there is formed an inductive loop about the warp element wl, and the inductive eifects of these loops are cumulative.

The form of winding shown in Fig. 3 is an improvement upon that of Fig. 2 in that all of the warp elements, including the warp elements at both selvedge edges, form the cores of noninductive solenoids.

Each pair of picks forms a bifilar winding, as-

in Fig. 2, but in addition the inductive loops formed at one selvedge edge annul one another.

. Specifically, the pick p1 is woven in the normal manner. In pick 102, however, the conductor passes over both warp elements 206 and 105, the

remainder of the pick being woven in the normal manner. The normal weave is continued for the remainder of pick p2 and all of pick p3. In pick p4, however, the conductor passes under both warp elements w6, w5. This'sequence is repeated through the weaving. As shown most clearly in Fig 3a, picks p1 and p2 form a bifilar winding lying side by side through the warp, except at the left-hand end where they loop about the warp 8! element w6. Similarly, the picks p3 and p4 form a bifilar section, lying side by side in the warp except at the left-hand selvedge edge, where they loop about the warp element w6. However, the loops formed by these adjacent pairs of picks, are 8: in opposition, the inductive efiect of one cancelling or annulling the inductive effect of the other. Similarly, throughout the pattern, each pair of picks forms a bifilar section, and the inductive loops'at corresponding ends of adjacent pairs of- 00 bifilar sections are in opposition. In view of the foregoing explanation it is apparent that with this type of weave, all of the warp elements are the cores of non-inductive solenoids, and that the residual reactance of a resistor so woven is negligibly small. I

In all of the described forms of woven re sistors, the distributed capacity is low, because of the fact that there is very small difi'erence of potential about the adjacent picks. As distin- "guished from a previously known type of resistor in which the distributed capacity is balanced against the distributed inductance, so that the resistance has insubstantial reactance for a given frequency, in accordance with my invention I independently reduce the inductance and capacity with the result that the reactance is low, for a substantial range of frequencies.

In Fig. 4, there is shown one method of mounting a woven resistor. The warp threads W, support the resistance unit R in the window or opening of a frame formed for example by a card 1 of suitable material as fibre, bakelite, or the like. Specifically, the ends of the warp threads are caught by threads 2 looped or stitched through holes in the card or frame 1. The terminal leads 1, 1 of the unit may be secured in, any suitable manner to the terminal card, forexample, the ends of the leads may be soldered to a loop of substantially heavier conductor 3. With this method of mounting both sides of the resistance r are exposed to the air, ofiering a substantial surface for radiation of heat, so that the efiective resistance is not appreciably affected by the current flowing through it.

Another method of mounting in which both sides of the resistance webbing I is exposed, is shown in Fig. 5. The ends of the warp projecting beyond the resistance unit proper, are clamped against the hollow supporting members 4 and 5, by the bars 6 and 7, as most clearly shown in the detail plan view of Fig. 5a. [If desired, and as indicated, the terminal leads 1, 1' may be soldered or otherwise connected to the mounting columns 4 and 5 which are suitably fastened to a block of insulating material 8 to form a mounted resistor unit- As shown in Fig. 6, the woven resistor may be bent around one end of a card 9 of suitable insulating material, with the warp elements, on opposite sides of the card, projecting towards the other end. The resistor is held against the card in any suitable manner, for example, by binding threads 10, 11, which are wrapped around the projecting warp elements. Alternatively, or in addition, the ends of the warpthreads may be caught against the card by the thread 12 which is looped or stitched through the card. The leads 1 and 1' are soldered or fastened to the eyelets 13, 14, forming a mounted resistor unit.

' In Fig. 7, the resistance webbing R is entirely on one side of a card 15. The resistance is held in place by cloth tapes 16 and 1'! which, respectively, bind the oppositeends of the warp threads against the card. If desired, and as shown in preceding figures, the warp threads may alternatively, or in addition, be held by threads stitched through the card.

In Fig. 8, the resistance R is mounted by wrapping it upon a frame or spool 18, which is preferably of some material having a low dielectric loss and substantially unaffected by changes in humidity, such as for example, isolantite. The webbing should be mounted so that the warp threads'are parallel to the axis of the spool to avoid bringing into proximity, portions of the resistance which are of substantially different potential and to insure low capacity effect of the resistance. The leads as indicated are preferably brought outat opposite ends of the spool. Bringing the leads out at the same end increases the capacity slightly and should be avoided when possible. As indicated, the resistor may be held in place upon the spool by binding threads 19 and 20 which are wrapped around the warp threads projecting from opposite ends of the woven resistor. Particularly if the' resistance is of substantial width, one or more additional binding threads 21, 22 may be wrapped around the mounted resistor intermediate its edges.

In Fig. 9, the resistance R is also wrapped upon a frame, as a spool 23, but in this case the resistance is wrapped upon itself in a spiral. As in Fig. 8, the webbing is mounted with the warp threads parallel to the axis of the spool. This method of mounting is particularly advantageous for high resistances since the capacities to ground can be decreased. considerably by so rolling the webbing, without appreciably increasing the capacity effect within the resistor. For example, the time constant of a 20,000 ohm woven resistor, mounted upon a 1.5 inch bakelite spool, in a single layer, as in Fig. 8, was 3.4x10- seconds, while the time constant of a similar resistor rolled on a inch frame, was 1.4x10- seconds.

With resistors woven in accordance with my invention and ranging from 20 to 20,000 ohms,

the variation of resistance with a frequency range of from zero to about 50,000 cycles, is not greater than the precision of measurement. For example, the resistance error in 10,000 ohm woven units is less than .01% for frequencies. from zero to at least 50,000 cycles; for resistances under 10,000 ohms the error is less, until at 1000 ohms it does not exceed 001%. For all values of resistances up to 10,000 ohms, the error at 1000 cycles is less than .001%.

Thepattern of weave of Fig. 10, also results in a woven resistor of very low time constant,

suited for high precision measurement. In this resistor, the style of weave has been termed cross-shot, because it is formed by the simultaneous weaving of two similar conductors on the warp, that is, one shuttle moves across the warp in one direction and another shuttle moves across the warp in the opposite direction before the harness of the loomtransposes the positions of the warp elements.

As shown clearly in Fig. 10, the first pick p1 of conductor C, and the first pick P1 of conductor C1, lie side by side, that is, both pass under the same alternate warp elements for example 1, 3, 5, etc., and pass over every other warp element, as 2, 4, 6, etc. Specifically, both picks pass under the warp element ml at one selvedge edge, and

as clearly indicated in Fig. 10, in which the size and spacing has been exaggerated to clearly show the relation of the picks to each other and to the warp elements.

In the completed resistor, the ends x, ml of the different conductors are connected together, and the ends y, 111 are likewise connected together. The effect of winding the resistor from two conductors as described and connecting them in this manner is readily apparent from Fig. 10a. In each pair of picks p1, P1; p2, P2; p3, P3; etc., the current in one pick is flowing in one direction, while simultaneously current of the same value is flowing in opposite direction through the other pick of the pair, so that in effect each pair of picks form a bifilar winding. The resistor is therefore non-inductive, the individual warp elements forming the cores of non-inductive solenoids.

From another aspect, it can be considered that the picks p1, p2, etc., of conductor C form inductive loops which are cumulative in their effect in causing the warp elements to be the cores of inductive solenoids, but the picks P1, P2, etc., of the conductor C1 also form inductive loops whose effects are cumulative but in opposition to the inductive effects of those of conductor C, with the result that the inductive effects of the individual windings annul each other.

The resistance webbing of Fig. 10 may be mounted in any desired manner, for example, in any of the various ways shown in Figs. 4 to 9.

It is also characteristic of this type weave that the variation in time constant is even materially less than the previously described modifications. An advantage ,of the weave shown in Fig. 10 is that it facilitates production of woven resistors of much lower value than can be conveniently 120 made with the styles of weaving shown in Figs.

2 to 3, which are more suited to the higher values of resistances. As it is difficult to weave resistors from wire larger than #35, the weaves of Figs.

2 and 3, are not as well suited for the lower re- 128 sistance values as the weave of Fig. 10 since the high resistance per unit length of .fine wire makes it diflicult accurately to adjust low values of resistance, and further the amount of wire used is so small that it is difiicult to obtain suflicient 130 radiating area for dissipation of heat. These difficulties are overcome in the cross-shot weave since fine wire, facilitating weaving, can be used and the lower values obtained by connecting the two conductors electrically in parallel. 138

Aside from the fact that thefcross-shot weave is better suited for the lower values of resistance, it has the further advantage that the inductance of a cross-shot woven resistor, having a certain resistance and certain total cross-sectional area for the two parallel wires, is appreciably less than that of a unit of the same resistance and cross-section produced by the methods of weaving of Figs. 2 or 3. The cross-shot woven resistor is specifically claimed in copending application of Tarpley and Behr, Serial No. 590,334, filed February 2, 1934.

While I have illustrated several preferred and specific forms of my invention, it is to be understood that my invention is not limited thereto but is comprehensive in scope with the appended claims. I

What I claim is:

1. A woven resistor comprising a warp of insulating material and in which adjacent picks of resistance conductor woven back and forth across the warp for carrying current in opposite directions lie side by side through the warp.

2. A woven resistor comprising a warp of insulating material and in which the picks of resistance conductor woven back and forth across the warp are disposed in pairs, with the picks of each pair disposed side by side across the warp, and with the picks of adjacent pairs crossing on opposite sides of elements of the warp.

3. A woven resistor comprising a warp of insulating material and in which each pair of picks of resistance conductor woven back and forth across the warp forms a bifilar section extending across the warp.

4. A woven resistor comprising a warp of insulating material and in which each .pair of picks of resistance conductor woven back and forth across the warp forms a bifilar section extending across the warp and encircling a warp element at the selvedge edge.

5. A woven resistor comprising a warp of insulating material and in which each pair of picks of resistance conductor forms a bifilar section extending across the warp and having a loop about a warp element at a selvedge edge, the

' alternate loops encircling said warp element in one direction and every other loop encircling said warp element in the reverse direction.

6. A resistor comprising a woven unit of resistance conductor and in which warp elements of insulating material constitute the cores of noninductive solenoids formed by the weaving of the conductor, and a form on which said unit is wrapped, without folding, with the warp elements substantially parallel to the axis of the form 10 ensure that the capacitative reactance shall be 7. A resistor comprising a woven unit of resistance conductor and in which warp elements of insulating material constitute the cores of non-inductive solenoids, and a form on which said unit is wrapped, without folding, in several layers with the warp elements substantially parallel to the axis of the form to reduce the constant of the resistor.

8. A woven resistor comprising a warp on which are woven picks of continuous resistance conductor, the relation of adjacent picks to each other and to the warp being such that the inductive eflects produced by looping of picks of conductor over and under warp elements are opposed by inductive eifects produced by looping of other picks over and under warp elements so-that they constitute the cores of non-inductive soleholds.

9. A woven resistor comprising a warp on which are'woven picks of continuous resistance conductor, the relation of adjacent picks to each other and to the warp being such that the inductive eflects produced by looping of picks of conductor over and under warp elements are opposed by inductive effects produced by looping of other picks over and under warp elements so that all warp elements constitute the cores of non-inductive solenoids. v

10. A woven resistor comprising a warp of insulating material on which is woven a single continuous resistanceconductor, all picks of said conductor having such relation to each other and the warp that elements of the warp constitute the cores of non-inductive solenoids.

11. A woven resistor comprising a warp of insulating material on which is woven a single continuous resistance conductor, all picks of said conductor having such relation to each other and the warp that all elements of the warp constitute the cores of non-inductive solenoids.

RAYMOND E. TARPLEY.

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