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Publication numberUS3638161 A
Publication typeGrant
Publication dateJan 25, 1972
Filing dateJan 14, 1971
Priority dateJan 14, 1971
Publication numberUS 3638161 A, US 3638161A, US-A-3638161, US3638161 A, US3638161A
InventorsDumas Christ J
Original AssigneeAmerican Plasticraft Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Modularized resistance unit
US 3638161 A
Abstract
A modularized electrical resistance unit for use in connection with high-voltage systems which comprises a casing body, a support boss mounted within the casing body, a resistance carrier mounted on the support boss and disposed within the casing body, and encapsulating material completely encapsulating the resistance carrier including the peripheral edges thereof. The casing body is provided with an enlarged chamber surrounding the anode terminal to accommodate a greater volume of encapsulating material, and a barrier wall and corresponding slot arrangement between the high-voltage and low-voltage terminals.
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Description  (OCR text may contain errors)

United States Patent Dumas 1 Jan. 25, 1972 [54] MODULARIZED RESISTANCE UNIT 3,441,895 4/l969 Schwartz ..338/256 [72] Inventor: Christ J. Dumas, Forest View, Ill. Primary Examiner E A Goldberg [73] Assignee: American Plasticraft Company, Chicago, At'or'ley-petherbridgev O'Neill & Lindgre" ill.

[57] ABSTRACT [22] Filed: Jan, 14, 1971 A modularized electrical resistance unit for use in connection PP N03 106,502 with high-voltage systems which comprises a casing body, a support boss mounted within the casing body, a resistance car- 52 us. Cl. ..338/256 174/52 PE 338/226 SuPP)rt and dispmd 338/315 ing body, and encapsulating material completely encapsulat- 511 rm. Cl ..H0lc 1 02 Si-glance carrier including Pe'iPhml edges 5s| Field of Search ..338/226 256 275 315- The casing is Pmvided with enlatged 336/96. 174/52 ,1 chamber surrounding the anode terminal to accommodate a greater volume of encapsulating material, and a barrier wall 56] References Cited and corresponding slot arrangement between the high-voltage and low-voltage terminals.

10 Claims, 6 Drawing Figures PATENTEDJANZSIQYZ 3.638.161

SHEET 1 8F 2 INVENTOR. CHRIST J. DUMAS ATTORNEYS.

PATENTEB JANZSISYZ 3,638,161

sum 2 er 2 INVENTOR CHRIST J. DUMAS PM, 77.014 BY ATTORNEYS.

MODULARIZEI) RESISTANCE UNIT BACKGROUND OF THE INVENTION This invention is directed to an improved modularized resistance unit for use in connection with high-voltage systems such as TV receivers, precipitrons, ignition systems, voltage control systems screen grid voltage systems in TV receivers, and the like. More specifically, this invention is directed to a modularized resistance unit wherein the resistance carrier is mounted within the casing body so as to enable complete encapsulation of the resistance carrier and the resistance element carried thereby including the peripheral edges thereof, and wherein the resistance carrier is prevented from either lateral, circumferential or other movement when mounted, thereby to increase the high-voltage breakdown characteristics of the resistance unit. In addition, the present invention provides an improved modularized resistance unit wherein a distinct barrier is provided between the high-voltage and low-voltage terminals for the purpose of increasing the breakdown voltage therebetween, as well as providing an increased anode terminal area chamber which thereby further improves the corona start voltage and the high-voltage discharge or breakdown voltage of the modularized resistance unit.

Modularized resistance units are known in the prior art. For example, there is disclosed in US. Pat. No. 3,441,895, issued on Apr. 29, 1969 to Jack Schwartz, a cermet resistance module which comprises a casing body having a resistance carrier carrying a resistance pattern deposited thereon disposed within the casing body, wherein the casing body is provided with a plurality of peripheral shoulders upon which the resistance carrier rests, and including encapsulating material which is injected into the casing body after the resistance carrier has been mounted therein in order to engulf and encapsulate the resistance carrier as well as the resistance element carried thereby. While resistance modules of the type set forth in the aforementioned patent have met with a fair modicum of success, nevertheless, certain difiiculties have been experienced with such modules.

One such problem resides in the fact that complete encapsulation cannot be accomplished due to the fact that peripheral shoulders are provided within the casing body upon which the resistance carrier is carried. In this manner, the encapsulating material is not capable of completely engulfing the peripheral edges of the resistance carrier and this construction provides a very easy breakdown path during abnormal highvoltage or arcing phenomena.

Another problem arises by virtue of the fact that during manufacture of such a resistance module, the resistance carrier is subject to movement within the casing body even after it has been placed upon the peripheral shoulders such that during the encapsulation process, the injection of the encapsulating material into the casing body may cause movement of the resistance carrier and thereby the resistance element deposited thereon effecting the electrical characteristics of the device.

Another problem resides in the fact that no distinct physical barrier has been provided between the high-voltage and lowvoltage terminal whereby the breakdown voltage as between these two terminals is at a high-stress level increasing the danger of electrical breakdown of the unit.

Finally, another problem exists by virtue of the fact that the area surrounding bulk and volume of encapsulant thereby providing a convenient breakdown voltage pathway.

Therefore, it is the principal object of the present invention to provide an improved modularized resistance unit having a casing body, a support boss mounted within the casing body extending upwardly from the bottom wall thereof for carrying a resistance carrier thereon, the resistance carrier having a re sistance element deposited thereon, the casing body having en enlarged chamber adjacent the anode terminal thereof, and a quantity of encapsulating material completely encapsulating and engulfing the resistance carrier and the resistance element carried thereby including the peripheral edges thereof in order to provide a modularized resistance unit having increased high-voltage breakdown characteristics and increased corona start voltage.

Another object of the present invention is to provide a modularized resistance unit of the type set forth wherein a distinct physical barrier is provided between the high-voltage and low-voltage tenninal areas in order to further increase the high-voltage breakdown characteristics of the unit as a whole.

Still another object of the present invention is to provide a modularized resistance unit of the type set forth wherein the resistance carrier is provided with a plurality of openings disposed therein to accommodate the insertion therein of the stripped lead wires in order to improve the mounting of the wires to the resistance element and thereby further increase the high-voltage breakdown characteristics of the unit and improve manufacturing efficiency.

Yet a further object of the present invention is to provide a modularized resistance unit of the type set forth wherein the means for mounting the resistance carrier on the casing body comprises a support boss mounted on the casing body and extending upwardly from the bottom wall thereof including a lower support section and a key member section thereon, and the resistance carrier provided with an opening designed to mate with the key member section of the support boss whereby once the resistance carrier is mounted upon the support boss, lateral, circumferential and other movement of the resistance carrier within the casing body is prevented.

Further features of the invention pertain to the particular arrangement of the parts whereby the above-outlined additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

FIG. I is a top plan view of one embodiment of the modularized resistance unit of the present invention;

FIG. 2 is a side cross-sectional elevational view of the invention taken in the direction of the arrows along the line 22 in FIG. 1;

FIG. 3 is an exploded fragmentary view showing the key member feature of the support boss and the corresponding mating section of the resistance carrier which provides a mounting means for mounting the resistance carrier upon the support boss;

FIG. 4 is a top plan view showing the casing body including the support boss and the enlarged anode chamber of another embodiment of the modularized resistance unit of the present invention;

FIG. 5 is a top plan view showing still another embodiment of the present invention wherein the casing body is provided with a physical barrier wall and the resistance carrier is provided with a corresponding and mating slot to accommodate the barrier wall; and

FIG. 6 is a top plan view showing the resistance carrier in accordance with one embodiment of the present invention and which further includes a series of three terminal-mounting holes for holding terminal lead wires in fixed relationship with respect to the resistance carrier.

With particular reference to FIG. 1 of the drawings, there is illustrated a modularized resistance unit generally referred to by numeral 10. The unit 10 generally includes a series of four sidewalls 11 extending upwardly from the peripheral edges of bottom wall 12 (see FIG. 2), a pair of mounting lugs 13 extending laterally outwardly from opposed sidewalls ll of the unit 10, each of the mounting lugs 13 including a mounting opening 14 disposed therethrough to accommodate a rivet, or bolt or other mounting device for mounting the unit 10 to the high-voltage system in which such unit is employed. The casing body of the unit 10 further includes a support boss generally referred to by the numeral 15 (more particularly shown in FIG. 2), which includes a lower support section I6,

and a key member section 17 extending upwardly from the upper surface of the lower support section 16 for a short distance. A resistance carrier 20 is generally shown in phantom in FIG. 1, which is provided with a key-mated opening 21, corresponding to the design of the key member section 16. The resistance carrier 20 includes a resistance element (not shown) deposited thereon, and further includes a high-voltage terminal 22, a low-voltage terminal 23, and a focus voltage terminal 24. Lead wire 25 is attached to high-voltage terminal 22 and extends outwardly therefrom through strain relief 26, lead wire 27 is attached to a low-voltage terminal 23 and extends outwardly through strain relief 28, and lead wire 29 is attached to focus or tapped voltage terminal 24 and extends outwardly therefrom through a strain relief 30.

As shown in FIG. 2 of the drawings, once the resistance carrier 20 has been suitably mounted by way of key-mated opening 21 upon key member section 17, and the lead terminal wires 25, 27 and 29, respectively, have been suitably inserted through the corresponding strain reliefs 26, 28 and 30, respectively, the casing body is filled with anencapsulating material 31 thereby to completely encapsulate and engulf the resistance carrier 20 including the resistance element carried thereon.

In the preferred embodiment, once the resistance carrier 20 is suitably mounted upon the lower support section 16 by inserting the key member section 17 through the key-mated opening 21, the upper section of the key member section 17 is heat pressed downwardly in order to form a rivet head 18 over the key-mated opening 21 thereby to firmly anchor the resistance carrier 20 in place. The manner of mounting the resistance carrier 20 upon the support boss 15 including the lower support section 16 and key member 17 thereof, is more clearly shown in FIG. 3 of the drawings.

In the embodiment shown in FIGS. 1, 2 and 3 of the drawings, once the modularized resistance unit has been assembled and encapsulated as described above, an electrically superior resistance module is obtained. By eliminating the peripheral supports for the resistance carrier 20, and by substituting therefore a single support boss for supporting the resistance carrier within the casing body, an increase in the high-voltage breakdown characteristics of the unit as a whole is realized.

In FIG. 4 of the drawings, there is illustrated another embodiment of the present invention which provides an even more electrically efficient modularized resistance unit. In this embodiment, there is shown a casing body 35 comprising a bottom wall 36, a first sidewall 37, a second sidewall 38, a third sidewall 39, and a fourth sidewall 40. Sidewall 39 includes an outwardly extending flange portion 41 and the fourth sidewall 40 includes an outwardly extending flange portion 42, the outwardly extending flange portion 41 and 42 being connected by a peripheral sidewall 43. Casing body 35 is further shown to include a support boss 45 including a lower support section 46 and a key member section 47. Finally, the casing body 35 is provided with mounting lugs 48 each of which has a mounting opening 49 disposed therethrough for mounting the casing body 35 to a supporting base (not shown). In addition, suitable strain reliefs 50 are provided as may be necessary for the terminal lead wires which extend outwardly from the terminals as discussed hereinabove. The height of peripheral wall 43 as well as the outwardly extending flange portions 41 and 42, and peripheral wall 39 extend upwardly for a height greater than the height of peripheral walls 37, 38 and 39 from a point designated at 51 to apoint designated 52, as shown in FIG. 4 of the drawings.

An anode terminal wire collar 53 is provided extending laterally outwardly from peripheral wall 43. The collar 53 is of an extended length in order to provide a longer axial dielectric path to' ground thereby further improving the breakdown characteristics of the module.

The purpose for having an enlarged chamber area surrounding the anode or high-voltage terminal of the modularized resistanceunit as assembled, and having an increased height in the sidewalls surrounding the anode chamber, is that once the resistance carrier is mounted within the casing body 35, and

' the encapsulating material injected therein, the high-voltage breakdown characteristics of the resistance unit as a whole is greatly increased. This increase in the high-voltage breakdown characteristics is the result of the mass and volume of the encapsulating material which surrounds the high-voltage terminal in the completed form.

In FIG. 5 of the drawings, there is illustrated the preferred embodiment of the invention wherein there is shown a casing body, generally designated by the numeral 55, including a bottom wall 56, a first sidewall 57, a second sidewall 58, a third sidewall 59, and a fourth sidewall 60. The third sidewall 59 includes an outwardly extending flange portion 61 and the fourth sidewall 60 includes outwardly extending flange portion 62, the outwardly extending flange portions 61 and 62, respectively, being connected by peripheral wall 63, in the same manner as described with respect to the embodiment shown in FIG. 4 of the drawings. Once again, the peripheral wall 63, as well as the outwardly extending flange portions 61 and 62 are of a height greater than the side walls 57 and 58 from a point designated at 64 along third sidewall 59 to a point designated at 65along fourth sidewall 60. Casing body 55 is further provided with a support boss 66 which is constructed in the same manner as the support bosses 15 and 45 described with respect to FIGS. 1, 2, 3 and 4 of the drawings. Casing body 55 is also provided with suitable strain reliefs 67 in order to accommodate the corresponding lead wires which extend from the associated terminals.

Casing body 55 is further provided with a barrier wall 70 which extends from the third sidewall 59 inwardly toward the central region of the casing body 55, the barrier wall 70 being integral with the third sidewall 59 as well as the bottom wall 56 of the casing body 55.

In FIG. 6 of the drawings, there is illustrated the resistance carrier, generally referred to by numeral 75, which is particularly adapted for use in connection with the casing body 55 illustrated in FIG. 5 of the drawings. The outer dimensions of resistance carrier are slightly less than the inner dimensions of the casing body 55, whereby the resistance carrier 75 may be positioned within casing body 55. Resistance carrier 75 is shown to include a key-mated mounting opening 76, which is designed to mate to the corresponding key member section of support boss 66 in the manner depicted in FIG. 3 of the drawings. The resistance carrier 75 further includes a slotted section 77 which extends inwardly from the peripheral edge of the resistance carrier 75 for a distance sufficient to accommodate barrier wall 70. Finally, the resistance carrier 75 is provided with a series of three lead wire mounting openings 78 disposed therethrough which facilitates the mounting of the corresponding lead wires to the resistance carrier 75.

The resistance carrier is generally formed of a nonconductive substrate usually fabricated from a material such as aluminum or steatite, although glass and other ceramics may be utilized, whereupon a resistance element, such as cermet, is deposited thereon. The resistance material, e.g., cermet, is deposited on the ceramic substrate in narrow strips which have a specific resistance per unit length. The substrate is then heated in order to permanently bond the cermet thereto. The resistance material, prior to encapsulation, may be further protected by coating such material with an electrical insulator, such as blue diallyl phthalate, or other suitable materials known in the art.

In the manufacture of the preferred embodiment of the modularized resistance unit referred to in FIGS. 5 and 6 of the drawings, the casing body 55 including the peripheral walls 57, 58, 59, 60, and the outwardly extending flange portions 61, 62, respectively, as well as the connecting peripheral walls 63, barrier wall 70, support boss 66, and the strain reliefs 67, are all formed as an integral unit or as a single piecemold. The preferred material for such casing bodies is a plastic of extremely low electrical conductivity. The resistance carrier 75 is formed in the manner indicated hereinabove, and the embodiment shown in FIG. 6 of the drawings is the preferred embodiment for use in connection with the casing body 55 shown in FIG. 5 of the drawings. The resistance carrier 75 having the I resistance element deposited thereon is suitably positioned within the casing body 55 by inserting the key member section of the support boss 66 through the key-mated mounting opening 76 thereby to securely position the resistance carrier 75 within the casing body 55. The lower surface of the resistance carrier 75 rests against the upper surface of the lower support section of the support boss 66 in a manner depicted in FIG. 3 of the drawings. By having a key member section and a-keymated mounting opening on the support boss and the resistance carrier, respectively, lateral, circumferential and all other forms of movement of the resistance carrier 75 with respect to the casing body 55 is substantially eliminated. Hence, greater economics in terms of manufacturing are effected in this manner since the number of rejects is substantially reduced due to the fact that accurate aligning may be done by a relatively unskilled operator during the positioning operation. The appropriate lead wires are inserted through the wire mount openings 78 disposed in a resistance carrier 75, and once again, this construction provides for a more economical manufacturing operation as well as improving the electrical characteristics of the module. That is, once the terminal wires have been suitably stripped, the ends of the wires are inserted through the openings 78 and thereby firmly held in position while the operator effects the soldering of the wire to the resistance carrier 75.

Once the terminal lead wires have been suitably soldered to the resistance carrier 75, and the resistance carrier 75 accurately positioned within the casing body 55, the encapsulating material is then injected into the casing body in order to completely engulf and encase the resistance carrier 75 including the resistance material deposited thereon. In this position, barrier wall 70 is fitted in the slotted section 77 of the resistance barrier 75, the electrical reasons being more fully described hereinafter. Of course, prior to encapsulation, the lead wires have been suitably threaded through corresponding strain reliefs such that once the encapsulating material hardens' within the casing body, the modularized resistance unit is ready for installation in a suitable high-voltage system.

The electrical circuitry involved in modularized resistance units of the type described herein, as well as the materials of which the various elements of such a unit are composed, are well known in the art as manifested by US. Pat. No. 3,44l ,895, referred to hereinabove, as well as other prior art patents. Hence, such details are not deemed necessary in connection with the improvements dealt with in the present invention. However, the construction of the present invention, especially the preferred embodiment thereof, results in certain very distinct electrical and manufacturing improvements over such prior art devices as will be more fully explained hereinafter.

In accordance with the description of the improved modularized resistance unit of the present invention, it will be appreciated that one of the principal features provided by the present invention is the complete encapsulation and engulfment'of the resistance element carried by the resistance carrier within the casing body. By providing a single support boss within the casing body upon which the resistance carrier is supported and carried, one can obtain complete encapsulation by the encapsulating material of the resistance element. It will be further appreciated that by the removal of the peripheral shoulders as indicated in the prior art devices, several highvoltage breakdown pathways are eliminated. In addition, this type of construction increases the corona start voltage to a higher value, on the order of 33 percent.

Present modularized resistance units have a corona start voltage of around 30 kv. whereas the corona start voltage of the preferred embodiment of the present invention has a corona start voltage of about 40 kv. on the average value basis. Hence, the dielectric strength of the modularized resistance unit is increased by not only the bulk, but also the volume provided by the increased amount of encapsulating material surrounding the resistance element. This result is obtained by first providing for the complete encapsulation as mentioned above, and secondly, by increasing the height of the peripheral walls around the anode or high-voltage area thereby to provide an even greater amount of bulk and volume of encapsulating material in and about the high-voltage area. l-Ience, what is basically achieved is an increase in the intrinsic volumetric and conformal coverage of the resistance element thereby increasing the high-voltage breakdown characteristics of the unit as a whole. While improved results are obtained with the embodiment of this invention as shown in FIGS. 1 and 2 of the drawings, even better results are obtained by the preferred embodiment shown in FIGS. 4 and 5 of the drawings.

With particular reference to the embodiment shown in FIG. 5 of the drawings, further improvement in the high-voltage breakdown characteristics of the module unit are obtained by virtue of the barrier wall 70 formed integrally with the casing body 55 which is in juxtaposition with the slot 77 formed in a resistance carrier 75. The barrier wall 70 provides a distinct physical barrier between the high-voltage terminal and the low-voltage terminal thereby to prevent an electrical breakdown and leakage pathways as between these two terminals. This results in longer life and reliability of the module system.

In addition, this structure limits and substantially eliminates spurious corona voltages which are generated between the aforementioned two terminals, thereby eliminating unwanted pulse interferences generated by corona discharges. It will be appreciated that a similar result is obtained if the resistance carrier 75 having a slot 77 is utilized even without a barrier wall 70 in the casing body 55 since without the barrier wall, upon encapsulation of the resistance carrier having the resistance element deposited thereon, encapsulating material will nest in the slot 77 thereby similarly providing a physical barrier and improving the breakdown voltage as between the two terminals. However, it has been found that by not only having the slot 77, but also the barrier wall 70 nested therein, an improved physical barrier is achieved and the breakdown voltage characteristics of the module system are greatly improved.

For example, a modularized resistance unit which is not encapsulated with encapsulating material and which does not have a slot in the resistance carrier and lacks a barrier wall will have a breakdown voltage as between the anode terminal and the cathode terminal at about 20 kv. A modularized resistance unit lacking encapsulation by encapsulating material and provided with a slot in the resistance carrier but no barrier wall will have a breakdown voltage at about between 22 and 23 kv., the reason for the slight increase being that there is an air dielectric path interrupting the breakdown path as between these two terminals thereby improving the breakdown voltage. A resistance module which lacks encapsulating material but is provided with a slot in the resistance carrier and with a barrier wall disposed therebetween will have a breakdown voltage at about 33 kv. for the reason that there is now provided a physical barrier which breaks down in the discharge path thereby further improving the breakdown voltage. As compared to the above units, a modularized resistance unit having substantially complete encapsulation but with no barrier wall and no slot in the resistance carrier, e.g., the type of modularized resistance unit as disclosed in US. Pat. No. 3,441,895, will have a breakdown voltage on the order of about 50 kv. However, the modularized resistance unit of the present invention further improves upon the breakdown voltage characteristics by as much as 30 percent. The embodiment as shown in FIG. 5 of the drawings having complete encapsulation by the provision of a single support boss and including a slot in the resistance carrier and a barrier wall disposed therebetween will have a breakdown voltage on the order of about 65 kv., thereby showing an increase of approximately 30 percent improvement in the breakdown voltage over prior art devices.

As was mentioned above, not only is the breakdown voltage of the unit as a whole improved by virtue of the construction of the present invention, but also, the reliability and longevity of the unit is improved while in use.

With particular reference to FIG. 6 of the drawings, there is shown a resistance carrier 75 which is shown to include a series of three wire mounting openings 78 disposed therein. The openings 78'are provided in approximately the centerline of the metallized connecting areas where wires are attached for connection to the respective resistance patterns. These openings 78 are used as added strength where the partially stripped lead wire is allowed to enter the opening 78 and allowed to fully bottom and then bent over and around the resistance carrier before the solder is applied. In this manner, lateral and axial strain relief to the lead is provided, and an improvement of the corona start characteristics is accomplished, which is important in high-voltage modules where corona starts or corona itself could be detrimental to the operation of the unit.

From a manufacturing standpoint, the openings 78 have additional value in that the operator may insert the stripped terminal lead wires through the openings 78 until the wires bottom, and then solder applied. This eliminates the step of requiring the operator to position the wires and manually hold the wire in position during the soldering operation. Obviously,

. if the operator does not accurately position the terminal wire on the resistance pattern, then the chances for additional breakdown pathways or leakage is greatly enhanced. Hence, not only does one obtain a more rounded, conformable and well uniform solder pattern area which results in a low corona connection of the terminal lead wires to the resistance element, but the manufacturing steps involved in assembling such a unit is rendered more efficient.

The module of the present invention can be utilized in many capacities. For example, such resistance module units can be used as a bleeder system to effect a constant impedance swamping a high-voltage power supply, thereby allowing the system to become somewhat voltage stabilized. Any overvoltage ripple or spikes which may reach voltages exceeding 60 kv. during the high-voltage arcing event in the unit, will cause the resistance module to act as a dampening device to quench or resist the high-voltage spikes or overvoltage and limit such overvoltages to about between and percent of the normal quiesent applied DC voltage. Such bleeders may also be used for focus application in TV receivers and will have the same characteristics related above with further overvoltage protection by virtue of the fact that since the voltage is impressed between the anode and focus taps, the overvoltage event will be further restricted because the focus tap of the picture tube is fully tracking or riding in direct relation to the overvoltage causing the focus impedance or resistance from focus tap to ground to load down the high voltage thereby to cause less cascaded arcing and a much quicker reaction to the arcing cleanup after an arcing phenomenon.

In addition to use in connection with bleeders in a TV receiver system, such modular resistance units also have use in precipitrons, in ignition systems, and voltage control systems, as well as screen grid voltage systems in TV receivers. Such units cause a constant idling current to flow from the power supply to the ground terminal, hence improved quieting of power supply operation is accomplished.

Hence, in accordance with the present invention, there has been provided an improved modularized resistance unit which substantially increases the breakdown voltage characteristics of the unit as a whole by minimizing leakage pathways or discharge breakdown pathways in the unit, minimizes the corona effect, improves the intrinsic module corona start voltage, and provide a more economic structure from a manufacturing standpoint. The modularized resistance unit of the present invention achieves a greatly improved electrical characteristic because the encapsulating material is allowed to completely encapsulate the resistance carrier and the resistance element patterndeposited thereon by the provision of a single support boss for carrying the resistance carrier. The support boss further functions to securely position the resistance carrier in a predetermined position minimizing and substantially eliminating lateral, circumferential, as well as all other forms or directions of movement of the resistance carrier within the casing body, especially during the encapsulation operation. ln this manner, more uniform results are obtained on a production basis where a plurality of units must be quickly and efficiently encapsulated during the manufacturing process. Furthermore, by the provision of terminal wire openings in the resistance carrier, the manufacturing process is further improved by enabling the operator to accurately position the wires and have the wire automatically held in place prior to the soldering operation. Therefore, an improved modularized resistance unit satisfying the objects and advantages set forth hereinabove has been provided by virtue of this'invention.

While there has been described what is at present considered to be preferred embodiments of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

lclaim:

1. In a resistance module having a casing body including a bottom wall bounded by peripheral sidewalls upstanding therefrom, at least one strain relief projection on the casing body, a resistance carrier, a resistance element including a pattern of cermet resistance material bonded to and carried by said resistance carrier, said resistance carrier having dimensions smaller than the internal dimensions of the casing body so as to be positionable within said casing body, the resistance element including electrical conductors connected thereto and extending therefrom which are engaged by the strain relief to firmly lock the electrical conductors in place when the resistance element is positioned within the casing body, and an encapsulating hardenable liquid material for encapsulating and engulfing the resistance element after positioning the samevwithin the casing body, the improvement comprising mounting means for mounting said resistance carrier within said casing body including a support boss-rnounted on said casing body and extending upwardly from the bottom wall thereof and positioned within the area bounded by the peripheral sidewalls thereof, and an opening provided in said resistance carrier, said opening having dimensions substantially equal to said support boss, whereby said resistance carrier may be mounted on and supported by said support boss through said opening thereby to enable the encapsulating hardenable liquid material to completely encapsulate the resistance element carried by said resistance carrier thereby improving the dielectric characteristics of said module.

2. The resistance module as set forth in claim 1 above, wherein said support boss includes a lower support section extending upwardly from the bottom wall of said casing body for a distance less than the height of the sidewalls thereof and an upper key member portion extending upwardly from the upper surface of said lower support portion, said key member portion being smaller in overall diameter than the diameter of said lower support portion, and said opening in said resistance carrier being formed to mate with said key member portion of said support boss whereby said resistance carrier may be positioned within said casing body by inserting said key member portion through said opening and having the lower surface of said resistance carrier supported by the upper surface of said lower support portion.

3. The resistance module as set forth in claim 2 above, wherein said key member portion extends completely through said opening in said resistance carrier, the upper portion of said key member portion being crimped to form a rivet head over the portion of said resistance carrier surrounding said opening thereby to hold said resistance carrier firmly in position.

4. In a resistance module having a casing body including a bottom wall and four sidewalls upstanding therefrom, at least one strain relief projection on the casing body, a resistance element including a pattern of cermet resistance material bonded to a slablike resistance carrier, the resistance carrier having dimensions smaller than the internal dimensions of the casing body so as to be positionable within the casing body, the resistance element including electrical conductors connected thereto and extending therefrom which are engaged by the strain relief to firmly lock the electrical conductors in place when the resistance element is positioned within the easing body, and an encapsulating hardenable liquid material for encapsulating and engulfing the resistance element after positioning the same within the casing body, the improvement comprising a support boss formed integrally with said casing body and extending upwardly from the bottom wall thereof and positioned within the area bounded by the sidewalls thereof, said central support boss extending upwardly for a distance less than the height of the sidewalls of the casing body and having a flattened surface on the upper end thereof, a key member portion extending upwardly from the upper surface of said central support boss for a distance whereby the. total height of said central support boss and said key member portion is substantially equal to the height of the sidewalls of the casing body, and an opening disposed through said resistance carrier, said opening being designed to mate with said key member portion, whereby the resistance carrier may be mounted on said central support boss and supported by the upper surface thereof by inserting said key member portion through said opening in the resistance carrier thereby to enable the encapsulating hardenable liquid material to completely encapsulate and engulf the resistance element bonded on the resistance carrier to improve the resistance characteristics of said module.

5. A resistance module comprising a casing body including a bottom wall and a plurality of sidewalls extending upwardly therefrom and peripherally thereabout to form a central chamber area, a portion of each of two adjacent of said sidewalls including outwardly extended portions, said outwardly extended portions being circumferentially connected by a sidewall thereby to form a chamber radially offset from said central chamber area, a support boss mounted on said casing body and extending upwardly from the bottom wall thereof and positioned within said central chamber area, a resistance carrier, a resistance element including a pattern of cermet resistance material carried by said resistance carrier, said resistance carrier having dimensions smaller than the internal dimensions of the casing body so as to be positionable within said central chamber area, at least one strain relief projection on the casing body and extending outwardly therefrom, said resistance element including electrical conductors connected thereto and extending therefrom which are engaged by said strain relief to firmly lock said electrical conductors in place when the resistance element is positioned within the casing body, said resistance carrier being provided with an opening therethrough, said opening having dimensions substantially equal to said support boss whereby said resistance carrier may be mounted upon and supported by said support boss by inserting said support boss through said opening, and an encapsulating hardenable liquid material encapsulating and engulfing the resistance element after positioning the same within the casing body, thereby to enable the encapsulating hardenable liquid material to completely engulf the resistance element bonded on said resistance carrier improving the dielectric characteristics of said module.

6. The resistance module as set forth in claim 5, wherein said resistance carrier is provided with a slot extending inwardly from a side edge thereof and terminating at a point adjacent to said opening disposed through said resistance carrier.

7. The resistance module as set forth in claim 6, wherein said casing body is provided with a barrier wall extending upwardly from the bottom wall thereof and extending from a sidewall thereof inwardly therefrom, said barrier wall being positioned so as to be in juxtaposition with said slot in said ceramic base when said resistance carrier is positioned within said casing body.

8. The resistance module as set forth in claim 5, wherein said support boss on said casing body includes a lower support section extending upwardly from bottom wall of said casing body for a distance less than the height of the sidewalls thereof and having a flattened surface on the upper end thereof, and an upper key member portion extending upwardly from the upper surface of said lower support portion for a distance whereby the total height of said lower support section and said key member section is substantially equal to the height of the sidewalls of the casing body, and wherein said opening in said resistance carrier is designed to mate with the key member portion whereby said key member portion is inserted through said opening and the lower surface of said resistance carrier rests upon the upper surface of said lower support portion of said support boss thereby to accurately position said resistance carrier upon said support boss and prevent lateral, circumferential and other movement of said resistance carrier when positioned within said casing body.

9. The resistance module as set forth in claim 5, wherein said sidewalls forming said radially offset chamber have a height slightly greater than the height of the remaining sidewalls thereby to form an enlarged radially ofiset chamber.

10. The resistance module as set forth in claim 5 wherein said resistance carrier includes a plurality of terminal wire mounting openings disposed therethrough to accommodate the insertion of the terminal wire therein thereby to provide improved anchoring sites and solder points for connecting the terminal wires to said resistance element.

Patent No. 3,638,161 Dated January 25, 1972 Inventor(s) Christ J. Dumas It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column I, cancel lines 64-66 and insert the following: Finally, another problem exists by virtue of the fact that the area surrounding the anode or high voltage terminal lacks sufficient bulk and volume of encapsulant, thereby providing a convenient breakdown voltage pathway.

Signed and sealed this 12th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM P0-1050 (10-69) uscoMM-oc 60376-P69 fi U.S. GOVERNMENT PRINTING OFFlCE I569 0-866-334.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 3 638 ,161 Dated January 25, 1972 Inventor(s) Christ J. Dumas It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, cancel lines 64-66 and insert the following: Finally, another problem exists by virtue of the fact that the area surrounding the anode or high voltage terminal lacks sufficient bulk and volume of encapsulant, thereby providing a convenient breakdown voltage pathway.

Signed and sealed this 12th day of December 1972 (SEAL) Attest:

EDWARD M.FLE TCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM PC4050 (169) USCOMM-DC 60376-P69 U-S. GOVERNMENT PRINTING OFFICE 1 I959 O-'36G-3J4,

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4154118 *Sep 15, 1977May 15, 1979Chrysler CorporationTransmission speedometer drive assembly
US4422122 *Feb 3, 1982Dec 20, 1983Fuji Electric Co., Ltd.Surge absorber
US5252944 *Apr 6, 1992Oct 12, 1993Caddock Electronics, Inc.Film-type electrical resistor combination
US5304977 *Apr 6, 1992Apr 19, 1994Caddock Electronics, Inc.Film-type power resistor combination with anchored exposed substrate/heatsink
Classifications
U.S. Classification338/256, 174/527, 338/226, 174/549, 338/315
International ClassificationH01C1/02, H01C1/16, H01C7/00, H01C1/00, H01C1/14
Cooperative ClassificationH01C1/02, H01C7/00, H01C1/14, H01C1/16
European ClassificationH01C7/00, H01C1/02, H01C1/16, H01C1/14