US2943966A - Printed electrical circuits - Google Patents

Description

July 5, 1960 LENQ ETAL PRINTED ELECTRICAL CIRCUITS 2 Sheets-She et 1 Filed Dec. 10, 1954 A Home y July 5,1960 J A LENO ETQAL 2,943,966 PRINTED ELECTRICAL CIRCUITS Filed Dec. 10, 1954 2 Sheets-Sheet 2 FIGS.

Inventor: J. A. LENO- A. M. SEARLE A ttorn e y PRINTED ELECTRICAL CIRCUITS John Albert Leno and Arthur Mackenzie Searl'e, London,

England, assignors to International Standard Electric Corporation, New York, N.Y.

Filed Dec. 10, 1954, $81. No. 474,566

Claims priority, application Great Britain Dec. 30, 1953 1 Claim. (Cl. 154-80) This invention relates to improved methods for making inductive windings for electrical apparatus.

Methods for producing what are commonly called printed circuits are well known and comprise forming conductive tracks upon an insulating surface such as by printing with, say, a conducting printing ink or electroplating or otherwise depositing the tracks upon the surface of an insulating carrier.

It is known from British Patent No. 639,591, to provide a carrier having a plurality of uniplanar turns of conducting track thereon which form an inductive winding.

The main feature of the present invention is a method of producing an inductive electrical winding which comprises printing or otherwise depositing a continuous conductive track on one surface of a fiat insulating carrier and folding the carrier through substantially 180 along a line crossed by the track whereby portions of the track on the carrier on each side of the line are brought into relative position about an axis at right angles to the surface of the carrier to form one turn of the winding.

The invention will be particularly described with reference to the accompanying drawings illustrating various embodiments.

In the drawings:

Fig. 1 illustrates in plan view a conducting track on an insulating carrier;

Fig. 2 is a perspective view of the carrier in Fig. 1 during folding;

Fig. 3 is a plan view of the carrier after folding has been completed;

Fig. 4 illustrates in plan view another embodiment having a more elaborate conducting track;

Figs. 5 and 6 are perspective views of the carrier in Fig. 5 at different stages of folding;

Fig. 7 is a plan view after folding has been completed;

Fig. 8 illustrates in plan view a further embodiment having a track comprising a plurality of loops or turns and Fig. 9 shows in perspective how a number of carriers may be folded together ot provide a transformer.

Referring first to Fig. 1 it will be seen that an insulating carrier, in the form of a piece of paper or fabric 1, which may have been impregnated with an insulating resin, has printed or otherwise deposited upon it in wellknown manner a conducting track 2 which may comprise silver or other metallic paste.

The carrier may be regarded as comprising a number of substantially equal sections or areas 3, 4, 5, 6 bounded by imaginary lines 7, 8, 9, shown dotted, along which the carrier will presently be folded. The shape of the track is such that, on each of the sections 3, 4, 5, 6, there is a portion 10, 1'1, 12 or 13, so shaped that when, for example, the carrier is folded through 180 along line 7 the portions 10, 11, on sections 3 and 4 combine, in plan, to form a substantially enclosed figure, such as a circle. Thus, when the carrier 1, is folded fan-wise about lines 7, 8, 9, as shown in Fig. 2, the portions 12,

2,943,966 Patented July 5, 1960 'ice' 13, on sections 5, 6 form a substantially complete turn as shown in Fig. 3 and, likewise, the portions 10, 1 1, on sections 3, 4 form another substantially complete turn immediately behind, the various portions being arranged to meet their neighboring portions at. the folding lines -i {7,-8, 9, or to be joined together as shown in Fig. 1 by means of short track lines 14. The track 2 may be terminated as shown by areas 15 to act as terminals. It will beappreciated that some means (not shown) of preventing contact between the track portions on adjacent jsections will be necessany, when folding takes place. Such means maybe by printing with'an insulating material or by interleaving, as will be explained in connection with Fig. 9.

The winding, as shown in Fig. 3 and which may have a hole therethrough for a core, may be suitably consolidated by heat and pressure in known manner. It will be understod that while the carrier 1 has been shown divided into only four sections 3, 4, 5, 6, thereby producing only a two-turn winding, it may be as long as desirable and be divided into any desired number of sec tions, bearing in mind that an even number of sections enables both the terminals 15 to appear on the outside faces of the winding.

In order that the carrier 1 shall not be unduly long, the track may be arranged as a substantially complete loop or turn as shown in Fig. 4. In this case the carrier 16 is arranged to be folded first along a centre line 17 as shown in Fig. 5 and then in fanwise or other fashion along lines 18, 19, 20, as shown, for example, in Fig. 6. The configuration of the track is such that portions 21, 22, ultimately form one turn, 23 and 24 another turn, and so on. Thus the track shown in Fig. 4 forms a winding having four turns when folded as in Figs. 5, 6, 7, the terminal areas 25, being conveniently arranged side by side at one end of the winding.

A considerably larger number of turns can be provided without appreciable increase in the size of the insulating carrier by arranging the track as shown in Fig. 8. In this case the track comprises a number of loops or turns arranged one within the next in spiral form.

In Fig. 8 the track is of the same general configuration as in Fig. 4, but consists of five loops or turns, 26, 27, 28, 29, 30, substantially equidistant one from the next. It will be obvious that when folded along the centre line 17, the portions 31, 3-2, 33, 35 together with the respective portions 36, 37, 38, 39, 40, each form complete turns and that when folded fanwise as already explained there are produced five times as many turns as were provided from the track in Fig. 4, that is to say, the track shown in Fig. 8 provides a coil having twenty turns.

Fig. 9 shows how two carriers, having tracks thereon as in Fig. 8, may be folded together so that the two windings have a substantially common axis and are thereby inductively coupled as in a transformer.

The two carriers which are here designated 31, 32 are insulated from one another by means of an insulating foil or blank carrier 33, shown shaded. Other insulating foils (not shrown) or extensions of the foil 33, may be inserted where required to prevent undesired contact between portions of the track on each of the carriers 31, 32. By suitable arrangement of the carriers 31, 32, the terminals of each of the windings may be arranged to appear on an outside face of the transformer.

-It will be clear to those skilled in the art that various methods of interleaving or folding together of carriers may be employed and that the insulating material used may be plastic material equally well as resin-impregnated paper or fabric.

Furthermore the carriers 31, 32 may be replaced by a.

single carrierhaving the two tracks comprising the two windings printed one on each side thereof.

While the principles of the invention have been described above in connection with specific embodiments,

and particular modifications thereof, it is tube -clearly" understood that this: description is .madeonly by :way of Y exampleand not asa limit-ationon-thescope of the in vention.-

What ,we claim is:

An inductive electrical winding; comprising an -insu1at ing carrier having portions folded back-against each other,

thus forming aplurality of parallel surfaces, a printed circuit on certain of said surfaces, each- 0f saidprintedcircuits havin the configuration of portions only -of a plurality of complete turnsabout an axis perpendicular to said surfaces and cooperatingwith corresponding turn portions on another one of said surfaces to form a corresponding plurality of complete turns, said cooperating dicular to. each other, the printed circuits being arranged so that :both ends of the continuous conductor formed thereby are on the same portion of said carrier.

References Cited-in. the-file of this patent UNITED STATES PATENTS 5

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