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Publication numberUS3648218 A
Publication typeGrant
Publication dateMar 7, 1972
Filing dateApr 12, 1971
Priority dateApr 12, 1971
Publication numberUS 3648218 A, US 3648218A, US-A-3648218, US3648218 A, US3648218A
InventorsKellerman David
Original AssigneeKellerman David
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Wound resistor arrangement
US 3648218 A
Abstract
A wound resistor arrangement having a very high-resistance value in a comparatively compact form is described herein. In the wound resistor, a multicoated flexible continuous body means is wound on a bobbin means. The body means comprises a substrate, which is dielectric in nature, and may comprise a dielectric filament, a dielectric tape, and electrically conductive wire coated with an inner dielectric coating, or an electrically conductive tape coated with an inner dielectric coating upon which is provided a coating of a high resistance, continuous, electrically conductive means. The high-resistance means is the resistive element for the resistor. An outer dielectric coating is provided on the outside of the high resistance, continuous, electrically conductive means for insulating adjacent turns of the body means as wound on the bobbin from each other and from adjacent layers of turns. Lead means are provided connected to each end of the high-resistance continuous electrically conductive mans and the length of the high-resistance electrically conductive means is selected to provide the desired resistance for the resistor. The invention also comprises arrangements utilizing such a wound resistor in which the resistance may be varied during utilization and, also, a coaxial arrangement in which the high-resistance, continuous, electrically conductive means is sandwiched between an electrically conductive coating deposited on the outside of the outer dielectric coating and the electrically conductive member of the substrate. Also the resistance is coated on a flexible base, the base being wound on a bobbin. A slide contact is used to form a variable resistor.
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Description  (OCR text may contain errors)

l United States Patent Kellerman 1 Mar. 7, 1972 [54] WOUND RESISTOR ARRANGEMENT the wound resistor, a multicoated flexible continuous body means is wound on a bobbin means. The body means com- [72] inventor: Dav'd Kenn-5mm 148.5 South L05 prises a substrate, which is dielectric in nature, and may com- Angeles' Cahf' 90035 prise a dielectric filament, a dielectric tape, and electrically [22] Filed: Apr. 12, 1971 conductive wire coated with an inner dielectric coating, or an electrically conductive tape coated with an inner dielectric PP 133,323 coating upon which is provided a coating of a high resistance,

continuous, electrically conductive means. The high-resistance means is the resistive element for the resistor. An

[52] outer dielectric coating is provided on the outside of the high 5 l] Int Cl lmlc 5/02 resistance, continuous, electrically conductive means for insu- 58] Fie'ld 176 21 l lating adjacent turns of the body means as wound on the bob- 7 bin from each other and from ad acent layers of turns. Lead means are provided connected to each end of the high-resistance continuous electrically conductive mans and the [56] References C'ted length of the high-resistance electrically conductive means is UNITED STATES PATENTS selected to provide the desired resistance for the resistor. The

invention also comprises arrangements utilizing such a wound 2,759,081 8/1956 Mounteer ..338/ 176 resistor in which the resistance may be varied during utiliza- 2,804,529 8/1957 Boums .,338/296 X ti'on and, also, a coaxial arrangement in which the high-re- Primary Examiner-E. A. Goldberg A tt0rney-Finkelstein and Mueth [57] ABSTRACT A wound resistor arrangement having a very high-resistance value in a comparatively compact form is described herein. In

sistance, continuous, electrically conductive means is sandwiched between an electrically conductive coating deposited on the outside of the outer dielectric coating and the electrically conductive member of the substrate. Also the resistance is coated on a flexible base, the base being wound on a bobbin. A slide contact is used to form a variable resistor.

14 Claims, 20 Drawing Figures PAIENTEWR 7:972 3,648,218

sum 2 UF 3 r PATENTEDMAR 7 I972 SHEET 3 [IF 3 Lf \se ZIZMHZIZZIM N VE/v TOA? DAV/0 KELLER/WAN By mf %m WOUND RESISTOR ARRANGEMENT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the electrical resistor art and more particularly, to an improved wound resistor arrangement for providing high resistance values in comparatively small physical envelopes.

2. Description of the Prior Art In general, with the known techniques utilized in manufacturing resistors, it is difficult to provide resistors in values over l-million megohms having good thennal stability and yet be comparatively small in physical size. One type of resistor utilized includes a deposition of a thin metallic film on either a flat or cylindrical substrate in which by either masking means or machining a narrow spiral resistive path therethrough is provided. Such resistors generally achieve resistance values on the order of 80,000 ohms per square or 1.6 megohms with a 0.050-inch wide conductive path per inch of path length. With this construction, of course, only a single layer and therefore,

only a fixed length depending upon the spiral path length is practical and values above 100,000 megohms in comparatively small sizes and comparatively low costs have generally not been achieved.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved high-resistance wound resistor arrangement.

It is another object of this invention to provide an improved wound resistor arrangement wherein comparatively high-resistance values are achieved in a comparatively small physical size resistor.

It is yet another object of the invention to provide an improved high-resistance small physically sized resistor that is comparatively inexpensive to fabricate.

The above and other objects of the present invention are achieved, according to one aspect of the invention, by providing a bobbin means, which may be either flat, cylindrical or have any other desired cross-sectional shape, and may be either solid or hollow. A multicoated, flexible, continuous body means is wound on the bobbin means a preselected number of turns and a preselected number of layers or turns. The body means generally comprises a dielectric substrate having preselected coatings thereon. The substrate may be a dielectric filament having a rectangular, cylindrical or other desired cross-sectional configuration or, alternatively, may comprise an electrically conductive member such as a fine wire, or electrically conductive flat tape member upon which is deposited a dielectric coating to provide the dielectric substrate.

A high-resistance, continuous, electrically conductive means is deposited on the substrate and the high-resistance, continuous, electrically conductive means provides the re- .sistance for the high-valued resistor of the present invention.

The high-resistance, continuous, electrically conductive means is coated with a dielectric coating to provide insulation between adjacent turns and/or adjacent layers of turns of the high-resistance, continuous, electrically conductive means. In these embodiments of the present invention wherein the substrate comprises an electrically conductive member coated with an inner dielectric layer, the high-resistance, continuous, electrically conductive means is electrically insulated from the electrically conductive member of the substrate by the inner dielectric coating.

In this embodiment of the invention an electrically conductive connection means is provided, at each end of the body means, connected to the high-resistance, continuous, electrically conductive means.

The length of the body means wound upon the bobbin means is selected from considerations of the desired resistance. For example, if the high-resistance, continuous, electrically conductive means comprises a coating on the substrate having a resistance of 10,000 ohms per square, with a substrate diameter on the order of 0.005 inches there could be provided a resistor having 600,000 ohms per inch of length of the body means. Thus, a wound resistor according to the present invention, having a length on the order of approximately one inch and a 0.0375 inch diameter can have a resistance on the order of 10,000 megohms. By increasing the resistance per square and decreasing the wire diameter and increasing, as necessary, the length of the bobbin means and thus, the length of the body means wound thereon, resistors according to the present invention exceeding lO-million megohms having a high stability and a low inductance and low capacitance can be provided in comparatively small size.

In other embodiments of the present invention, wherein the substrate comprises a dielectrically coated electrically conductive member, the opposite ends of the electrically conductive member of the substrate may be joined together to reduce capacitance effects. Additionally, if desired, a shielding electrically conductive coating on the external surface of the outer dielectric coating can be provided so that the high resistance, continuous, electrically conductive means of the body member is shielded between the coaxial arrangement of the electrically conductive member of the substrate and the shielding coating. Such an arrangement has distinct advantages for distributed capacitance for delay line applications.

In another embodiment of the invention, the substrate may, for example, be a dielectric flat ribbonlike means and the high-resistance, continuous, electrically conductive means provided thereon and having a width less than the width of the substrate so that an area free of the high-resistance, continuous, electrically conductive means is provided on each side thereof on the substrate. In such an embodiment a variable resistance is provided by incorporating one of the lead means connection to a slide means that engages the external surface of the high-resistance, continuous, electrically conductive means.

Additionally, the resistor may be trimmed to comparatively precise values. For a fixed length of the multicoated, flexible, continuous body means that is wound on the bobbin means, if it is desired to reduce the total resistance, this may be accomplished by reducing the length of the high-resistance, continuous, electrically conductive means on the body means. Such reduction in length may be achieved by removing the outer dielectric coating from a few adjacent turns of the body means and applying a conductive material, such as an electrically conductive epoxy, on the exposed high-resistance, continuous, electrically conductive means over those turns. This effectively provides a very low resistance path through those turns that are thus shorted together and the total resistance for the given length of the multicoated, flexible, continuous body means is reduced.

In order to provide an increase in the resistance for a given length of multicoated, flexible, continuous body means, the outer dielectric coating from several adjacent turns may be removed and only a portion of the high resistance, continuous, electrically conductive means removed from these turns. Since only a portion is removed, the cross-sectional area of the portion remaining of the high-resistance, continuous, electrically conductive means on the body means is smaller, and therefore, the resistance therethrough is greater. A dielectric coating such as a nonconductive epoxy, or the like, may be applied over the portions of the body means from which the portion of the high-resistance, continuous, electrically conductive means has been removed.

Further adjustments between higher and lower resistance values may be made by combining the above steps as desired to reduce the cross-sectional area or short out adjacent turns to decrease the equivalent length of the resistor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates one embodiment of a wound resistor according to the present invention;

FIG. 2 illustrates a cross-sectional view of the resistor shown in FIG. 1;

FIGS. 3, 4, 5, 6, 7 and 8 illustrate various multicoated, flexible, continuous body means useful in the practice of the present invention;

FIG. 9 illustrates another embodiment of the present inven tion;

FIGS. 10, 11, 12, 13, 14, 15, 16 and 17 illustrate other multicoated, flexible, continuous body means useful in thepractice of the present invention;

FIGS. 18 and 19 illustrate another embodiment of the present invention; and

FIG. 20 illustrates another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before providing a description of the preferred embodiments of the present invention is is to be pointed out that the many variations in the structural components comprising the present invention may be variously interchanged to provide wound resistors according to the present invention in any desired configuration. For example, as described below in greater detail, the bobbin means upon which the multicoated, flexible, continuous body means is wound, may be solid, hollow, rectangular in cross section, circular in cross section, tubular, or any other desired configuration. Similarly, the many different forms of the multicoated, flexible, continuous body means may be utilized on any of the different types of bobbin means to provide a high degree of flexibility in design selection. Additionally, the exact configuration of the lead connections to the resistor may be varied between the different types of bobbin means and the different types of multicoated, flexible, continuous body means utilized. Thus, the following description and the accompanying drawings are provided for illustrative purposes only and illustrate specific embodiments. The present invention, however, is not limited by the specific embodiment illustrated but is only limited by the scope of the claims appended hereto.

FIGS. 1 and 2 illustrate an improved wound resistor arrangement, generally designated 10, having a dielectric bobbin means 14 having walls 12 defining a tubular passageway 13 therethrough. Upon an outer surface 15 there is wound a multicoated, flexible, continuous body means 16. The multicoated, flexible, continuous body means 16 is wound on the bobbin means a preselected number of turns and with a preselected number of layers of turns. In this embodiment of the invention shown in FIGS. 1 and 2 there is provided three layers of turns. It will be appreciated that the number of turns and the numbers of layers of turns may be selected as desired to achieve a specific resistance since the resistance is dependent upon the total length of the multicoated, flexible, continuous body means 16.

The multicoated, flexible, continuous body means 16 has a first end 18 adjacent a first end 20 of the bobbin means 14 and a second end 22 adjacent a second end 24 of the bobbin means 14.

A first lead means 26 at the first end 20 of the bobbin means 14 is electrically connected to the first end 18 of the body means 16 by a first electrically conductive connection means 28. A second lead means 30 is electrically connected to the second end 22 of the body means 16 by a second electrically conductive connection means 32. In this embodiment of the invention, shown in FIGS. 1 and 2, the first and second electrically conductive connection means are substantially identical. It will be appreciated, however, that different lead connection arrangement can be provided as desired for each of the first and second lead means 26 and 30. That is, the first and second electrically conductive connection means 28 and 32, respectively, may be the same or one of them may be of different configuration, such as the various electrically conductive connection means described below in connection with other embodiments of the invention.

The bobbin means 14 is a cylindrical tubular member having an axis 34 and interior walls 12 defining a tubular passageway 13 extending from the first end 20 to the second end 24 thereof. The first and second electrically conductive connection means 28 and 32 are, in this embodiment of the invention, generally comprised of a lug means 36 and 38, respectively, extending through the tubular passageway 13 to regions external the bobbin means 14 for connection to the leads 26 and 30, respectively.

Each of the lug means 36 and 38 have portions 36a and 38a extending through the bobbin means to the outer wall 15 thereof for electrically conductive connection to an electrically conductive ring member 40 and 42, respectively.

As shown more clearly in FIGS. 3 and 4, the multicoated flexible continuous body means 16 is generally comprised of a substrate 44 which, in this embodiment of the invention, comprises an electrically conductive member 46 which may be a fine wire means or the like. In order to provide electrical insulation, the substrate 44 also comprises an electrical insulation 7 means such as electrical insulation coating 48 deposited thereon from the first end 16 to the second end 22 thereof.

A high-resistance continuous electrically conductive means 50 which may take the form of a coating on the electrical insulation coating 48 is deposited thereon and, in this embodiment of the invention, has a predetermined resistance per unit length and forms the high-resistance path in the present invention. It will be appreciated that the electrical insulation means 48 provides electrical insulation between the electrically conductive member 46 and the high resistance continuous electrically conductive means 50.

A dielectric coating 52 is provided on the high-resistance continuous electrically conductive means 50 to provide electrical insulation between adjacent turns and between layers of turns for the high-resistance path.

As shown more clearly on FIG. 2 the high-resistance continuous electrically conductive means 50 has a first end margin portion 54 at the first end 18 of the multicoated flexible continuous body means 16. The first end margin portion 54 provides electrical connection to the first electrically conductive connection means 28 and thus to the lead 26. In order to achieve the electrical continuity from the high-resistance continuous electrically conductive means 50 the outer dielectric coating 52 is removed from the end margin portion 54 thereof which, as shown on FIG. 2 comprises the three adjacent turns at the first end 20 of the bobbin means 14. An electrically conductive protective coating 60, which for example, may be an electrically conductive epoxy, is provided over the first end margin portion 54 to protect the high-resistance continuous electrically conductive means 50 and insure good electrical continuity to the first lead connection means 28. Similar electrical continuity from the high-resistance continuous electrically conductive means 50 at a second end margin portion 62 which is at the second end 22 of the multicoated flexible continuous body means is provided for electrical connection to the second electrically conductive connection means 32.

In this embodiment of the invention, with the three layers of turns, the second end margin portion 62 is wound onto the ring member 42 from the outermost layer of turns, as indicated by the dotted lines 66. Thus, a continuous path through all three layers of turns is provided by the high-resistance continuous electrically conductive means 50.

In order to reduce capacitance effects in the wound resistor 10, it may be desired to provide a shunt wire 68 that is connected to the electrically conductive member 46 of the substrate 44 in the passageway 13. In installation, the shunt wire 68 may be connected to any desired reference voltage in the circuit, such as a ground connection.

Thus, the shunt wire 68 extends from a first end 46a of the electrically conductive member 46 to the second end 46b thereof for a continuous electrical shunt path throughout the length of the multicoated flexible continuous body means 16.

While the above-described embodiment of this invention shown in FIGS. 1, 2, 3 and 4 incorporate a substrate 44 having a generally cylindrical cross-sectional configuration, it will be appreciated that other cross-sectional configurations may be utilized. For example, in FIGS. 5 and 6 there is shown a multicoated flexible continuous body means 80 having a substrate 82 generally comprised of a rectangular electrically conductive tape like means 84 having a dielectric coating 86 thereon. In this embodiment of the multicoated flexible continuous body means 80 the high-resistance continuous electrically conductive means 88 is deposited on the electrical insulation means comprised of the dielectric coating 86 to provide the high-resistance electrical path. An outer dielectric coating 90 is on the high-resistance continuous electrically conductive means 88 to provide electrical insulation between adjacent turns and/or adjacent layers of turns when the multicoated flexible continuous body means 80 is wound on a bobbin means in a manner such as that illustrated in FIG. 2.

It has also been found that providing the high-resistance continuous electrically conductive means sandwiched between two electrically conductive coatings may have certain advantages in distributed capacity for delay line use.

FIGS. 7 and 8 illustrate one form of a multicoated flexible continuous body means generally designated 100 providing such a coaxial arrangement. As shown in FIGS. 7 and 8 the substrate 102 may be comprised of an electrically conductive member 104 which, as shown in FIGS. 7 and 8, may be a cylindrical fine wire similar to the electrically conductive member 46 shown in FIGS. 3 and 4. The substrate 102 also comprises an inner dielectric coating 105 to provide electrical insulation means between the electrically conductive member 104 and the high-resistance continuous electrically conductive means 106 that forms the high-resistance path for the multicoated flexible continuous body means 100. A dielectric coating 108 is provided on the high-resistance continuous electrically conductive means 106 to provide electrical insulation between the high-resistance continuous electrically conductive means 106 and an electrically conductive shielding coating 110 that is provided on the outer dielectric coating 108. Electrically conductive shielding coating 110 may be, for example, a golddeposited coating and thus the high-resistance continuous electrically conductive means 108 is sandwiched between the electrically conductive member 104 and the shielding coating 110.

FIG. 9 illustrates an embodiment of the present invention wherein the multicoated flexible continuous body means utilized is the body means 100 shown in FIGS. 7 and 8. This embodiment of the invention, generally designated 112 is similar to the embodiment of the invention shown in FIGS. 1 and 2 except that only one layer of turns of the multicoated flexible continuous body means 100 is provided on the external wall 114 of a cylindrical tubular bobbin means 116 having internal walls 118 defining a tubular passageway 120 therethrough. The multicoated flexible continuous body means 100 has a first end portion generally designated 122 and the high-resistance continuous electrically conductive means 106 has an end margin portion generally designated 124 at the first end 122 of the multicoated flexible continuous body means. The end margin portion 124 is generally comprised of the last two turns of the multicoated flexible continuous body means and the shielding coating 110 and outer dielectric coating 108 are removed from the multicoated flexible continuous body means on the end margin portion comprising the last two turns of the high-resistance continuous electrically conductive means. An electrically conductive contact means 126 is provided on the external wall 114 of the bobbin means 116 as part of the electrically conductive connection means generally designated 128. The electrically conductive contact means 126 insures good contact for electrical continuity to the highresistance continuous electrically conductive means 106.

The electrically conductive connection means 128 also comprises an electrically conductive member such as an electrically conductive epoxy 130 over the end margin portion 124 of the high resistance continuous electrically conductive means and the lead means 132 may be bonded in the electrically conductive epoxy 130.

A shunt wire means 134 may be connected to the electrically conductive member 104 of the substrate 102 for functioning as a shunt wire in a manner similar to the shunt wire 68 shown in FIG. 2 in order to reduce capacitance and/or inductive effects in the resistor. 1

In order to insure electrical insulation of the high-resistance continuous electrically conductive means 106, insulating means are provided on the multicoated flexible continuous body means for insulating the high-resistance continuous electrically conductive means 106 from the electrically conductive shielding coating 110. In the embodiment of the invention as shown in FIG. 9 the insulating means for providing this insulation is the outer dielectric coating 108 in the two turns immediately adjacent to the end margin portion 124 of the high-resistance continuous electrically conductive means 106. Thus, in these two turns the electrically conductive shielding coating is removed and the outer dielectric coating 108 insulates the electrically conductive shielding coating 110 from the high-resistance continuous electrically conductive means 106.

In the embodiments of the invention described above the substrate of the multicoated flexible continuous body means has generally comprised an electrically conductive member upon which there is provided a dielectric coating. It will be appreciated that the substrate may also comprise a dielectric means. FIGS. 10 and 11 illustrate one embodiment of a mu]- ticoated flexible continuous body means generally designated that has provided a dielectric substrate 142 which, for example, may be a glass fiber, a plastic fiber or the like. In the embodiment of the multicoated flexible continuous body means 140 shown in FIGS. 10 and 11 the substrate 142 is cylindrical in cross section.

A high-resistance continuous electrically conductive means 144 is provided on the substrate 142 and is the high-resistance path in the multicoated flexible continuous body means 140. An outer dielectric coating 146 is provided for insulation of the high-resistance continuous electrically conductive means 144 when the multicoated flexible continuous body means 140 is wound on a bobbin means and utilized in a manner similar to that described in the embodiments of the invention shown in FIGS. 2 and 9 above.

The dielectric substrate may be any desired cross section configuration. FIGS. 12 and 13 illustrate a multicoated flexible continuous body means generally designated 150 useful in the practice of the present invention in which a dielectric substrate 152 is in the form of a flat dielectric tape. The substrate 152 has a high resistance continuous electrically conductive means 154 thereon and an outer dielectric coating 156 is provided for electrical insulation of the high-resistance continuous electrically conductive means 154.

An electrically conductive shielding coating may also be provided in those embodiments of the invention wherein the substrate comprises a dielectric means. For example, FIGS. 14 and 15 illustrate a multicoated flexible continuous body means generally designated 160 in which there is provided a dielectric substrate 162 generally comprised of a cylindrical dielectric filament which may be similar to the substrate 142 shown in FIG. 10. A high-resistance continuous electrically conductive means 164 is on the substrate 162 to provide the high-resistance path. An outer dielectric coating 166 is provided for insulating the high-resistance continuous electrically conductive means between adjacent turns and layers of turns thereof. An electrically conductive shielding coating 168 is provided on the outer dielectric coating 166 and the electrically conductive shielding coating 168 may be similar to the electrically conductive shielding coating 110 shown in FIGS. 7, 8 and 9. It will be appreciated, however, that in those embodiments of the present invention wherein the substrate comprises only a dielectric member, a coaxial shielding arrange ment or a shunt wire cannot be utilized.

The present invention may also be equally well utilized in a potentiometer or variable resistor application. FIGS. 16 and 17 illustrate an embodiment of a flexible continuous body means useful in the practice of the present invention for potentiometer applications. As shown in FIGS. 16 and 17 a flexible continuous body means generally designated 170 is comprised of a dielectric substrate 172. The dielectric substrate, in this embodiment of the invention, comprises a dielectric rectangular tape means. A high-resistance continuous electrically conductive means 174 is provided an upper surface 176 of the substrate 172 and the width of the high-resistance continuous electrically conductive means 174 is less than the width of the dielectric substrate 172 so that there are edge margins 176a and 176b on the supper surface 176 of the substrate 172 that are not coated with the high-resistance continuous electrically conductive means 174. FIGS. 18 and 19 illustrate a wound resistor generally designated 180 according to the present invention utilizing the flexible continuous body means 170 wound on a bobbin means 182. The bobbin means 182 is, in this embodiment of the invention, a cylindrical dielectric means.

A first electrically conductive connection means 184 is generally comprised of an electrically conductive slide means 186 slidably mounted on the high-resistance continuous electrically conductive coating means 174. The slide means 186 is slidably movable thereon in directions indicated by the arrow 188 in generally axially directions. A first lead means 190 is coupled to the slide means.

A second electrically conductive connection means 192 is generally comprised of an electrically conductive means such as an electrically conductive epoxy 194 covering the second end margin portion 196 of the flexible continuous body means 170. A second lead means 198 is connected to the electrically conductive epoxy means 194.

As the slide means 186 moves in axial directions as indicated by the double-ended arrow 188 the number of turns of the high-resistance continuous electrically conductive means 174 between the slide means 186 and second lead means 198 is increased or decreased thereby increasing or decreasing the total length of the resistance path and thus the total resistance of the wound resistor 180.

While the embodiments of the present invention described above illustrate the lead connection arrangements to the wound resistor at opposite ends of the wound resistor, other embodiments of the present invention may have the lead connection arrangements at the same ends thereof. FIG. 20 illustrates a wound resistor arrangement generally designated 200 according to the present invention wherein there is provided a tubular cylindrical bobbin means 202 upon which is wound a multicoated flexible continuous body means generally designated 204. The multicoated continuous flexible body means 204 may be, for example, similar to the multicoated flexible continuous body means 140 illustrated in FIGS. and 11. As such it is generally comprised of a fine cylindrical fiberlike dielectric substrate 206 upon which is a high-resistance continuous electrically conductive means 208. An outer dielectric coating 210 is provided on preselected portions of a high-resistance continuous electrically conductive means. A first end margin portion 212 of the high-resistance continuous electrically conductive means is free of the outer dielectric coating 210 in order to provide electrical connection thereto. In the embodiment of the invention shown on FIG. there are provided four layers of turns and, consequently, the second end margin portion designated 214 of the high-resistance continuous electrically conductive means 208 is at the same end 202a of the bobbin means 202 as the first end margin portion 212. The second end margin portion 214 is also free of the outer dielectric coating 210.

The first electrically conductive connection means generally comprises an electrically conductive member such as an electrically conductive epoxy 216 connected to the first end margin portion 212 and a first lead 218 is attached thereto for electrical continuity to the high-resistance continuous electrically conductive means 208. Similarly, a second electrically conductive connection means which may be a similar electrically conductive epoxy 220 is connected to the second end margin portion 214 of the high resistance continuous electrically conductive means 208 for electrical continuity thereto and a second lead means 222 is affixed to the electrically conductive epoxy means 220.

A unique feature of a wound resistor according to the present invention is that it may be trimmed for either higher or lower resistance values in a very precise manner. For example, in order to reduce the total resistance the outer dielectric coating of the multicoated flexible continuous body means may be entirely removed from a few adjacent turns and these turns then shorted together to lower the resistance value thereof. An electrically conductive epoxy may be utilized to provide the shorting between the thus-exposed adjacent turns of the high-resistance continuous electrically conductive means.

In order to increase the resistance of the resistor a portion of the outer dielectric coating and a corresponding portion of the high-resistance continuous electrically conductive means lying thereunder may also be removed. Since only a portion of the high-resistance continuous electrically conductive means is removed the cross-sectional area thereof is thereby decreased and the'electrical resistance of the remaining portion of the high-resistance continuous electrically conductive means is thereby increased. A dielectric protective coating may be placed over the turns where the portion of the outer dielectric coating and the high-resistance continuous electrically conductive means have been removed for protection. Thus, trimming the capacitor to precise values either higher or lower than the existing value may be done by repeating the above trimming steps one or more times until the exact value is obtained.

As noted throughout the specification the bobbin means may be dielectric electrically conductive, may be rectangular in cross section, round in cross section or tubular in cross section. Similarly, any other desired bobbin configuration may be utilized in the practice of the present invention.

It has been found that with a resistive coating of 10,000 ohms per square and a substrate diameter of 0.005 inches, a resistance of 10,000 ohms is attained for each 0.016 inches of length of the multicoated flexible continuous body means. Thus. 600,000 ohms per inch of length of the body means is achieved. A wound resistor fabricated with the body means of the above construction can achieve 10,000 megohms in a 1- inch bobbin length having 0.375 inches diameter. Proportional increases in the total resistance of the wound resistor can be made by increasing the length of the flexible continuous body means and thus by increasing the length or diameter or both of the bobbin means resistors exceeding 1 million megohms having high stability low inductance and low capacitance can be manufactured. As noted, such resistors can also be trimmed with very high accuracy to any desired absolute value.

It has been found that the multicoated flexible continuous body means may be conveniently fabricated by deposition coating successively applied. Thus, the substrate, which may be either a dielectric filament, flat ribbonlike tape or the like, or an electrically conductive member coated with a dielectric coating may be continuously fed through a vacuum deposition coating chamber to add the high resistance continuous electrically conductive means as a coating thereon in a precisely controlled thickness of deposition. The outer dielectric coating may be added by a further successive deposition coating of a dielectric material on the high-resistance continuous electrically conductive means. In those embodiments of the invention wherein a shielding coating is then applied, a further deposition step can be utilized to provide such a shielding coating. Further, it has been found that if it is desired to increase the metallic thickness of the shielding coating and/or to provide better solder ability or weld ability, the multicoated flexible continuous body means may be continuously fed through a plating bath in order to apply a thicker shielding inner dielectric coating may be an enamel, plastic or ceramic applied by means other than vacuum deposition on the electrically conductive member of the substrate.

it has been found that by careful selection of the materials utilized as a substrate and as the high-resistance continuous electrically conductive means of the multicoated flexible continuous body means virtually any desired variation of resistance with temperature may be achieved. For example, if the high-resistance continuous electrically conductive means is a deposited coating of nickel and the substrate has a rather large thermal expansion characteristic, comparatively large variations in resistance with temperature may be obtained. Conversely, if the substrate has a low expansion characteristic such as quartz or an invar-type low-expansion wire coated with a dielectric coating be provided with such a nickel highresistance continuous electrically conductive means a comparatively low change in resistance with temperature would be obtained.

This concludes the description of preferred embodiments of the present invention. It will be appreciated that many variations and changes in structural details may be accomplished by those skilled in the art. Therefore, the following claims cover all such variations and adaptations.

What is claimed is:

1. An improved wound resistor arrangement comprising, in combination:

a bobbin means;

a multicoated, flexible continuous body means wound on said bobbin means a preselected number of turns and a preselected number of layers of turns, and said multicoated, flexible body means having a first end portion and a second end portion, and said multicoated, flexible body means comprising:

a substrate;

a high-resistance, continuous, electrically conductive means on at least preselected portions of said substrate, and said high-resistance, electrically conductive means having a predetermined resistance per unit length thereof, and said high-resistance electrically conductive means having a first end margin portion at a first end of said body means and a second end margin portion at a second end of said body means;

an outer dielectric coating on preselected portions of said high-resistance continuous, electrically conductive means for providing electrical insulation thereof between adjacent turns and layers of turns;

and said substrate comprising electrical insulation means for electrically insulating said substrate from said high-resistance, continuous electrically conductive means;

a first lead means;

a first electrically conductive connection means coupled to said first lead means and to said first end margin portion of said high-resistance continuous electrically conductive means for providing an electrically conductive connection relationship therebetween;

a second lead means;

a second electrically conductive connection means coupled to said second lead means and to said second end margin portion of said high-resistance, continuous electrically conductive means for providing an electrically conductive connection relationship therebetween.

2. The arrangement defined in claim 1 wherein: said substrate comprises:

an electrically conductive thin wire means having a first end portion at said first end of said body means and a second end portion at a second end of said body means, and having a predetermined cross-sectional configuration; and

a continuous, inner dielectric coating means on said thin wire means from said first end portion thereof to said second end portion thereof, and said second dielectric coating means intermediate said thin wire means and said high-resistance, continuous, electrically conductive means for electrical insulation therebetween.

3. The arrangement defined in claim 2 and further comprisan electrically conductive shunt wire means coupled to said first end portion and to said second end portion of said thin wire means for providing an electrically conductive path therethrough.

4. The arrangement defined in claim 3 and further comprismg:

an electrically conductive shielding coating on said first dielectric coating intermediate said first end of said body means to said second end of said body means;

an insulating means on said body means for electrically insulating said electrically conductive shielding means from said thin wire means and from said high-resistance electrically conductive coating means.

5. The arrangement defined in claim 2 wherein:

said first electrically conductive connection means further comprises:

a first electrically conductive contact on said bobbin means connected in electrically conductive relationship to said first end margin portion of said high-resistance electrically conductive means; and

said second electrically conductive connection means further comprises:

a second electrically conductive contact means on said bobbin means connected to electrically conductive relationship to said second end margin portion of said high resistance electrically conductive means;

and said first lead means coupled to said first electrically conductive contact means and said second lead means coupled to said second electrically conductive contact means. 6. The arrangement defined in claim 4 and further comprismg:

said first electrically conductive connection means further comprises:

a first electrically conductive contact on said bobbin means connected in electrically conductive relationship to said first end margin portion of said high resistance electrically conductive means; and

said second electrically conductive connection means further comprises:

a second electrically conductive contact means on said bobbin means connected in electrically conductive relationship to said second end margin portions of said high-resistance electrically conductive means;

and said first lead means coupled to said first electrically conductive contact means and said second lead means coupled to said second electrically conductive contact means; and

shielding insulation means intermediate said shielding means and said first end margin portion and said second end margin portion of said high resistance electrically conductive means for providing electrical insulation therebetween.

7. The arrangement defined in claim 3 wherein:

said predetermined cross-sectional configuration of said thin wire means is substantially circular.

8. The arrangement defined in claim 3 wherein:

said predetermined cross-sectional configuration of said thin wire means is substantially rectangular.

9. The arrangement defined in claim 1 wherein:

said substrate comprises a dielectric element means having a predetermined cross-sectional configuration.

10. The arrangement defined in claim 9 and further comprising:

an electrically conductive shielding coating on said outer dielectric coating from said first end of said body member to said second end thereof; and

insulation means on said body means for electrically insulating said electrically conductive shielding coating from said high resistance electrically conductive means.

11. The arrangement defined in claim 10 and further comprising:

said first electrically conductive connection means further comprises:

a first electrically conductive contact on said bobbin means connected in electrically conductive relationship to said first end margin portion of said high resistance electrically conductive means; and

said second electrically conductive connection means further comprises:

a second electrically conductive contact means on said bobbin means connected in electrically conductive relationship to said second end margin portion of said high-resistance electrically conductive means, and said first electrically conductive contact means electrically insulated from said second electrically conductive contact means;

and said first lead means coupled to said first contact means and said second lead means coupled to said second contact means.

12. An improved wound resistor arrangement comprising,

in combination:

a bobbin means having a first end and a second end;

a flexible body means wound around said bobbin means a preselected number of turns and a preselected number of layers thereof, and said flexible body means having a first end and a second end and said flexible body means comprising:

a dielectric substrate;

and a high-resistance continuous electrically conductive means on said substrate, and said high-resistance continuous electrically conductive means having a predetermined resistance per unit thereof, and having a first end margin portion at said first end of said flexible body means and a second end margin portion at said second end of said flexible body means;

a first lead means;

a first electrically conductive connection means coupled to said first lead means and to said first end margin portion of said high-resistance continuous electrically conductive means for providing an electrically conductive relationship therebetween;

a second lead means;

a second electrically conductive connection means coupled to said second lead means and to said second end margin portion of said high-resistance, continuous electrically conductive means for providing an electrically conductive connection relationship therebetween.

13. The arrangement defined in claim 12 wherein:

said dielectric substrate comprises a substantially flat, ribbonlike flexible continuous dielectric means having an upper surface and a lower surface, spaced-apart side surfaces and a predetermined width between said side surfaces;

said high-resistance continuous electrically conductive means comprises a continuous coating means on said upper surfaces of said dielectric substrate intermediate said side surfaces and having a predetermined width of said dielectric substrate, and defining side margins on said upper surface of said dielectric substrate adjacent each of said side surfaces free of said high-resistance electrical coating;

and said flexible body means wound on said bobbin means to provide said lower surface of a first layer of said dielectric substrate adjacent said bobbin means in said first layer thereof and said high-resistance, continuous, electrically conductive means spaced outwardly therefrom.

14. The arrangement defined in claim 13 wherein:

said first end of said flexible body means is adjacent said first end of said bobbin means and said second end of said flexible body means is adjacent said second end of said bobbin means; 1

said first electrically conductive connection means further comprises: an electrically conductive slide means mounted on said flexible body means in electrically conductive sliding relationship with said high resistance electrically conductive means and moveable axially in an electrically conductive relationship therealong; and said first lead means is coupled in electrically conductive relationship to said slide means; whereby movement of said slide means along said high-resistance electrically conductive means varies the resistance between said first lead means and said second lead means.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2759081 *Mar 15, 1954Aug 14, 1956G M Giannini & Co IncPotentiometer brush
US2804529 *May 1, 1953Aug 27, 1957Bourns IncWire wound element
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US8061402Apr 7, 2008Nov 22, 2011Watlow Electric Manufacturing CompanyMethod and apparatus for positioning layers within a layered heater system
US8070899Aug 25, 2010Dec 6, 2011Watlow Electric Manufacturing CompanyMethod and apparatus for positioning layers within a layered heater system
US8089337Jul 18, 2007Jan 3, 2012Watlow Electric Manufacturing CompanyThick film layered resistive device employing a dielectric tape
US8557082Jul 18, 2007Oct 15, 2013Watlow Electric Manufacturing CompanyReduced cycle time manufacturing processes for thick film resistive devices
WO2009012369A2 *Jul 17, 2008Jan 22, 2009Watlow Electric MfgThick film layered resistive device employing a dielectric tape
Classifications
U.S. Classification338/160, 338/305, 338/296, 338/298, 338/176, 338/300, 338/211, 338/143
International ClassificationH01C10/30, H01C17/00, H01C10/00, H01C1/14, H01C1/142, H01C17/04
Cooperative ClassificationH01C1/142, H01C10/301, H01C17/04
European ClassificationH01C17/04, H01C1/142, H01C10/30B