CA1105578A - Metallized film capacitors - Google Patents
Metallized film capacitorsInfo
- Publication number
- CA1105578A CA1105578A CA360,215A CA360215A CA1105578A CA 1105578 A CA1105578 A CA 1105578A CA 360215 A CA360215 A CA 360215A CA 1105578 A CA1105578 A CA 1105578A
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- Prior art keywords
- metallized
- capacitor
- dielectric layer
- pleated
- layer
- Prior art date
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Abstract
METALLIZED FILM CAPACITORS
Abstract of the Disclosure The present invention provides a product which has all of the many advantages of pleated, wound, electrical capacitors and also has the added advantage that it may be manufactured with commercially available metallized die-lectric materials. A further advantage of the present invention is that the same basic starting materials may be used to manufacture capacitors that have a number of different pleating combinations. Thus, the invention provides for an electrical capacitor segment which comprises a dielectric layer having a center line, a first metallized electrode layer applied to one side of the dielectric layer so that an unmetaillized margin ex-tends along each edge of a pair of parallel edges of the di-electric layer, and a second metallized electrode layer applied to the other side of the dielectric layer so that an unmetallized area is located adjacent the second metallized electrode layer.
The dielectric layer is pleated once along the unmetallized areas off of the center line so that one edge of the margin containing edges extends beyond the other of the edges along the same end of the capacitor segment and metallized spray material in contact with the second electrode layer.
Abstract of the Disclosure The present invention provides a product which has all of the many advantages of pleated, wound, electrical capacitors and also has the added advantage that it may be manufactured with commercially available metallized die-lectric materials. A further advantage of the present invention is that the same basic starting materials may be used to manufacture capacitors that have a number of different pleating combinations. Thus, the invention provides for an electrical capacitor segment which comprises a dielectric layer having a center line, a first metallized electrode layer applied to one side of the dielectric layer so that an unmetaillized margin ex-tends along each edge of a pair of parallel edges of the di-electric layer, and a second metallized electrode layer applied to the other side of the dielectric layer so that an unmetallized area is located adjacent the second metallized electrode layer.
The dielectric layer is pleated once along the unmetallized areas off of the center line so that one edge of the margin containing edges extends beyond the other of the edges along the same end of the capacitor segment and metallized spray material in contact with the second electrode layer.
Description
~1~5578 METALLIZED FII.M CAPACITORS
Background of the Invention This application is a division of Canadian Seria1 No. 305,939, filed June 21, 1978.
Electrical capacitors made of thin film dielectric material which ~s metallized on both sides are used in large quantities in electrical devices because of their reliability, their desirable elect-rical characteristics and their relatively low cost. ~nited States Patent No. 2, 470, 826 issued on May 24, 1949 to W. McMahon illus-trates a capacitor in which a double sided metallized dielectric layer is folded an odd number of times in a longitudinal direction. ~he folded dielectric material may then be wound along its lon~iludinal dimension and end terminations may then be applied to it by spraying of metal against the edges of the wound capacitor segment. rrhe type of capacitor described by McMahon patent i~ extremely desirable be-cause substantially all of the dielectric layer of the capacitor is in the electric field and the capacitor may be made without the insertion of an additional dielectric layer in the main body of the capacitor, although a short initial unmetallized dielectric strip and a protective terminating dielectric strip may be employed with the capacitor, if defiired.
~he type of capacitor construction that s envisioned by McMahon patent has a number of decided manufacturing and electrical advantages.
For example, the problem of masking the dielectric layer during elect-rode evaporation when the electrode areas are applied to the film is su~-stantially redused. In addition, no slitting is required as it is during the .~" .
11(~5578 manufacture of conventionat wound ~ilm capacitors. Furthermore.
the capacitance per unit dielectric area is maximized bccause of the substantially full use of the dielectric layer in the electric field. Shorter winding lengths per unit capacitance are thereby required, reducing the winding labor. ~he dielectric lengths can also be calibrated and pre-cut to produce a capacitor of more accurate values. Another advantage of thi~ bpe of capacitor i8 that there are no air layers between the metallized electrodes and the pleated film surfaces and this substantially increases the voltage, for example, one hundred volts or more, at which corona discharge starts, making this capacitor commercially attractive for new applications such as fluorescent lighting circuits. Previously, fifty gauge film thickness or more was required of wound film capacitors to withstand the corona. With the capacitor of the present invention, thirty-two gauge or less dielectric film thickness may be utilized, making ~und film capa-citors economically feasible for such applications.
~ he McMahon patent guggested that leads could be attached to his capacitor by the well-known Schoop process. ~he application of high velocity metallic spray coatings tothe edges of the capacitor described by Mc~qahon is not commercially practical, however, because thc spray wi~ penetr~te through the dielectric area at a pleat and thereby short one electrod~ to the other. If the temperature and pressure of the spray are lowered, penet-ration of the dielectric layers may be reduced but the adhesion of the metallic spray will generally be very poor. Ihe multiple leads suggested in the McMahon patent also are not satisfactory since they tend to tear the dielectric , ll(~S578 material and to make the capacitor bulky ancl inductivc.
In order to solve the above mentioned spray shorting problem at a pleated edge, it has been suggested in Australian Patent No. 159, 958, patented on November 24, 1954 to provide unmetallized dielectric strips behind all of the pleats of a pleated metallized capacitor. While this solution may provide a technically feasible method of attaching leads to apleated metallized dielectric layer capacitor, the number of unmetallized strips that are required on the dielectric layer greatly complicates the manu-facturing proce~ for both the dielectric layer itself and the pleated capacitor product. For example, in a capacitor having five pleats, there must be, in addition to the two unmetallized n~argin areas, five unmetallized strips that run along the entire length of the diclectric malerial,with three of these strips being on one side of the dielectric layer and two of these strips being on the opposite side of the dielectric layer, It iB
apparent that the masking problems and the cost of manufacturing such a specialized item make the solution of the Australian patent commercially unattractive. lhis is especially true since the type of metallized dielectric layer that is u$ed in the capacitor of the present invention, (in which only the margin areas and one unmetallized central strp is required), is readily commercially available. ~urthermore, the employment of an unmetallized strip behind the single pleated capacitor of the McMahon patent, however, -still would not proYide an end termination along the opposite edge of the wound capacitor segment that would allow a metallized spray to be applied to this edge because the ends of the dielectric layer of the McMahon patent at this edge extended beyond both of the melallized electrodes and contact between the metallic spray and the inner e]ectrode area would thereby be prevented .
il~S578 ~}~e leads of the capacitor of the Vnited States Patent No. 3, 854, 075, i ssued l)eceml~cl~ 10, 1974 to John Philip Uhl, were used as mandrels to wind the pleated capacitor segment about the center, in a manner similar to that suggested in United States Patent No. 2, 887, 64g issued May 19, 1959 to Daniel B. Peck. In the Uhl patent, conductive foil tabs were inserted between the leads and the metallized electrode areas to make positive contact with the electrode and to protect the electrode from damage by the leads during winding. However, it has been determined that this construction leads to a higher failure rate than desirable due to opening of the electrode area around the periphery of the metal foil, for reasons which are not completely understood.
~he configuration of the capacitor of the present invention provides a product which has all of the advantages of single pleated, or single pleated and wound, capacitors and also has the added advantage that it may be manufactured with commercially available metallized dielectric material. A further advantage of the present invention is that the same basic starting material may be used to manufacture capacitors having a number of different pleating combinations, which, of course, is not true for the capacitor of the Australian patent, in which each pleat combin-ation requires a specially manufactured die~ectric layer. In addition to the use of the present invention to manufacture wound film capacitors, it is also possible to utilize the invention to produce ceramic capacitors in which the capacitor dielectric material is folded while the ceramic material is still in a "green" state, in a manner similar to that dis-closed in United States Patent No. 3, 223, 494 issued December 14;
1965 to J. W. Crownover.
il~557~
Thus broadly, the invention contemplates an electrical capa-citor segment which comprises a dielectric layer having a center line, a first metallized electrode layer applied to one side of the dielectric layer so that an unmetallized margin extends along each edge of a pair of parallel edges of the dielectric layer, and a second metallized electrode layer applied to the other side of the dielectric layer so that an unmetallized area is located ad-jacent the second metallized electrode layer. The dielectric layer is pleated once along the unmetallized areas off of the center line 10 so that one edge of the margin containing edges extends beyond the other of the edges along the same end of the capacitor segment and metallized spray material is in contact with the second electrode layer.
In a further embodiment the invention contemplates an electri-cal capacitor segment which comprises at least one group of pleated layers comprising a dielectric layer, a first metallized electrode layer applied to one side of the dielectric layer so that an un-metallized margin extends along each edge of a pair of parallel edges of the dielectric layer, a pair of metallized electrode 20 layers on the other side of the dielectric layer, and at least one unmetallized strip that runs between the metallized layers on the other side of the dielectric layer. The dielectric layer is pleated M number of times where M = a ~ (N)b where a is an odd number 3 or greater, and b is an even number 2 or greater, and where N may be zero or any positive integer so that at least one pleat of the pleated dielectric strip extends along one end of the pleated dielectric layer beyond at least one other pleat that extends along the same end as the extending pleat, or pleats, with all of the extending pleats having unmetallized strips behind them 30 along their length. The edges of the metallized dielectric strip which contain the margins extend along the opposite end of the pleated dielectric layer beyond the other ple~ts that extend along the same end as the margin containing edges, wherein the extending pleat or pleats along the one end of the dielectric layer and the margin containing edges along the other end of the dielectric layer are sufficient in length to allow metallized spray material to be sprayed against both of the ends without penetration of the spray far enough to contact any of the pleats except the extending pleat or pleats.
'~7' ~l~SS78 In another broad aspect, the invention comprehends an electrical capacitor segment which comprises at least one group of pleated layers including a dielectric layer, a first metallized electrode layer applied to one side of the dielectric layer so that an unmetallized margin extends along one edgs of a pair of parallel edges of the di-electric layer, and a second metallized electrode layer applied to the other side of the dielectric layer so that an unmetallized margin area extends along the opposite parallel edge of the dielectric layer. The dielectric layer is pleated an even number of times so that the margin areas of the pleated dielectric strip extend along their respective ends of the pleated dielectric layer beyond the other pleats that extend along the same end as the respect`ive margin areas, with the margin areas facing outwardly from adjacent pleats and metallized spray material sprayed against regions of the metallized electrode layers in the vicinity of the margin areas which face inwardly toward adjacent , pleats on both of the ends, but without penetration of the spray far enough to contact any of the pleats.
ll~SS78 Description of the Drawings :
~he present invention is illustrated by reference to the drawings in which:
Fig. 1 is a perspective view of a portion of a metallized dielectric layer which may be used in the construction of a capacitor in accordance with the present invention;
F'ig. 2 is a perspective view of a partially pleated metallized di-s~.' electr~c layer in accordance with Fig. 1 having five pleat lines;
. ~,, - ~
Fig. 3 i8 a perspective view of a fully pleated dielectric layer in accordance with Fig. 1;
Fig. 4 is a perspective view of the fully pleated dielectric layer of Fig. 3 which, in addition, shows a winding mandrel and an unmètallized dielectric insert;
Fig. 5 is a diagrammatic showing of the winding of a ... .
capacitor segment in accordance with the construction of Fig. 4;
Fig. 6 is an end view of a capacitor segmcllt, bcfore le~d attachment, that is wourd in accordance with the showing of Figs.
4 and 5;
Fig. 7 is an end view of the wound capacitor segment of Fig. 6 after it has been pressed into an oval shape;
Fig. 8 is a side view of ~ comptetcd c;~ citor follo~ hc attachment of axial leads;
g .
ll~S578 Fig. 9 is a side view of a completed capacitor following attach-ment of radial leads;
Fig. 10 is a perspective view of an alternate version of a capacitor constructed in accordance with the present invenLion;
Fig. 11 is a perspective view of an additionat alternate embodi-ment:
Fig. 12 is a perspective view of a further alternate embodiment;
Fig. 13 is a perspective view of a portion of a metalliz~d dielectric layer which may be used in the construction of a capacitor in accordance . 10 with the present invention;
~?ig. 14 is a perspective view of a ~ingle pleated dielectric layer in accordance with ~ig. 13;
Fig. 15 is a perspective view of the fully pleated dielectric layer of Fig. 14 which, in addition, shows a winding mandrel and an unn~etallized dielectric insert;
Fig. 16 is a diagrammatic showing of the winding of a capacitor segment in accordance with the construction o Fig. 15;
Fig. 17 is a perspective view of a portion of a metallized dielectric layer which may be used in the construction of a capacitor in accor-dance with the present invention;
Fig. 18 is a perspective view of a plcated metalli%eLl diclc~ctric layer in accordance with Fig. 17 having two pleat lines;
,~
ll(~5S78 ~ ig. 19 is a diagrammatic showing of the winding of a capacitor segment in accordance with the construction of F`ig. 18; and Fig. 20 is a perspective view of an alternate version of a capacitor constructed in accordance with the present inventioll.
~echnical Description of the Invention A portion of a commercially available metallized dielectric strip which may be unwound from a reel, that is suitable for the- mal;ing of a capacitor in accordance with the present invention is shown in Fig 1.
The metallized dielectric strip is formcd with a dielcctric l~ycr 12 oî
a thin film dielectric material, such as polyester, polypropylene, poly-styrene, polycarbonate or other ~suitable material. ~ thin metallized electrode layer 14 i6 applied to the upper surface of the dielectric layer 12 in such a fashion that unmetallized margin areas 16, 18 e~;tend along the longitudinal edges of the strip 10. 'ru~O thin mctallizcd elcctrode areas 20, 22 are applied to the lower surface of the dielectr;c layer 12 so that the metallized layer 20 extends to the left hand margin of the layer as shown in Fig, 1, while the metallized layer 22 extends to the right hand margin of the layer. A central unmetallized stri~ 24 lies between the metallized electrode areas 20, Z2.
In the embodimellt shown in Fig. 1, the longituàill~l dinlellsion of the metallized strip 10 is shown along the arrows ~6 while the narro~
11(~5578 transverse dimension is shown along the arrows 28. ~he capacitor is pleated along the imaginary line 30 which extends through the length of the unmetallized central strip 24. 'rhis version of the prescllt invention, however, is not limited to one in which folding is along longitudinal lines S since a capacitor could be mad~ in accordance with the present invention by pleating along transverse lines if the appropriate corresponding metallized and unmetallized areas were provided.
A partially pleated capacitor is shown in Fig, 2 wherein one pleat occurs along the longitudinal center line 30 and othcr pleats occur along the longitudinal pleat lines 32, 34, 36 and 38. It is to be noted that lines 32, 34, 36 and 3~ are spaced so that the center pleat 40 ex-tends beyond the other pleats 42, 44 that run along the right hand long-itudinal edge of the metallized strip 10 of Fig. 1 so that the inside of the pleat 40 in the area 4G is unmetallized. ~he e~;tension of tlle center pleat 40 beyond the pleats 42, 44 is preferably at lcast 0. 020 inches. In addition, it is noted that the pleats are positioned so that the lOngitudinal ends 48, 50 of the metallized strip 10 are aligned with each other but so that they extend beyond the pleats 52, 54 that run along the left hand longitudinal edge of the metallized strip. Again, the ex-tension of the ends 48, 50 beyond the ple~ts 52, 54 is pleferably at lcasL
0. 020 inches. ~he unmel;allized margin 16, therefore, faccs upwardly while the unmetallized margin 1~ faces downwar-31y whcn thc capacitor ll~SS'7~
segment has been fully pleated as shown in ~ig. 3.
After the capacitor has been proccssed to form the capacitor seg-ment shown in Fig. 3, a number of different additional processing steps may be undertaken. ~or example, the pleated capacitor segment of ~ig. 3 could be used to form a capacitor merely by spraying the right and left hand longitudinal edges of the segment with a metallized spray, such as babbitt or other suitable metal, in accordance with convcntional practice, and then electrical leads could be secured to them, ior e~;ample, by soldering. Alternately, the capacitor segment of ~ig. 3 could be cut along a transverse line, such as the line 43, and a number of such seg-ments could be stacked upon each other, with the terminal end 50 of one capacitor segment being adjacent to and aligned with the terminal cnd 48' of the capacitor segment tl~at is positioned immecliatel~ belo~ it, as ShOWIl diagrammatically by the dotted line representative of ~ig. 3, and tllen their ends could be sprayed with a metallized spray and leads could then be secured to the stacked array OI such segments. In conjuncticn with the p resently pxeferred embodiment of the present invention, however, I;`ig. 3 represents two layers of a capacitor segment formed by ~vindinK of the di-electric strip along the longiLudinal dimellsion of the stril~ 10, ~s sl~o~vn inFigs. 9 and 5, to form a wound capacitor. Another version of this capacitor could be acllieved, however, by pleating the capacitor segment of Fig. 3 a number of times transversely along transverse fold lines such as the linc 43, or alternately pleating several times, and then completing the segment by winding the remainder of the length of the dielectric strip.
~he winding of the ca~)~citor scgmellt Or I;`ig. 3 into a ~ound capacitor may be achieved with various winding techniques, includin~ the use of a removable split mandrel such as the mandrel 5G of Figs. 4 and 5.
An unmetallized dielectric strip 58 is desirably initially wound around the mandrel to protect the metallized electrode areas of the metallized strip 10. Near the completion of winding, an additional unmetallized dielectric strip 60 is desirably wound into the structure to form all outer protective coating. ~he dielectric strip 60 may also be heat-sealed to itself to form the pleated capacitor segment 61 which is shown in Fig. 6. ~he removal of the mandrel 56 from the capacitor segment 61 leaves an opening 62 in the unit. ~he opening 62 may be closed by applying pressure, or pressure and heat, in accordance with the type of dielectric lsccl and convention.~l manufacturing techniques, to the cap~citor segn~cnt ~1 so that it assul~-cs an oval shape as shown in Fig. 7.
Once the capacitor segment of the embodiment of Figs. 4 through 7 has been wound, a metallized spray may then be directed against the longitudinal edges of the unit in accordance witll corlventional processing techniques to intercollncct thc elcc~rode 1a3 cr s alo1l~ tllese edges and to provide for the connection of electrical leads to thc unit.
~Ihe metalllzed spray wilt penetrate into the open area betwecll the ends 48 and 50 on the left hand longitudinal edge of the capacitor segment, as shown diagrammatically in Fig. 3 to a depth such as that indicated -r i~
ll(~S578 by the plane G5. 'rhe plane 65 indicates the maximum depth that any high velocity spray particles will pcnetratc and it l-la~ t]l~lS l~c~ locatcd any place between the ends 48 and 50 of the metallized strip 10 and the edges of the pleats 52, 54. Accordingly, the metallized spray material ;~ will extend into the left hand opening of the capacitor between the ends 48, 50 far enough to make contact to the t~vo facing metallized electrode areas 20, 22, but not so far that it will penetrate through the dielectric material at the pleats 52, 54. ~he configuratioll of tlle present ir~vention thus provides for reliable lead termination at the left hand longitudinal edge of the capacitor segment of Fig. 3 witl~out the necessity of providing unmetallized longitudinal strips along the inside of the pleats 52, 54, thereby saving considerable processing expenses in the manufacture of completed capacitors of this type.
'lermination to the right hand longitudinal edge of the capacitor 1~ segment of Fig. 3 is similarly provided by a metallized spray uh ich ex-tends over the protruding center pleat 40 to a depth~ such as that indicated by the plane 67, which is sufficient to allow the metallized spray to make good contact to the electrode area 14, but which will prevent the penetration of the spray metallic par~iclcs through the diclect-ric at the pleats 42, 44. ~he locationof the plane ~7 may l~e anywhere between the edges of the pleats 42, 44 and the cdge of the yleat 40 as long as there is sufficient depth of spray to provide adcquate contact -termination to the electrode area 14. Again, a considerable cost savin~s ll~SS78 is achieved by thc prescnt invention since thc ~leats 42, 44, lilce lhc pleats 52, 54, did not have to be provided with tl~eir own unmetallized strips. It will be noted in the present invention that only one unmetallized strip 24 is required in the center of the metallized strip 10, and, thus, the same general pattern may be used for various pleat configurations and a ~eparate individually configurat~d mctallizcd st3i1) is nol rcquircd for each pleat pattern.
.
Once the metallic spray has been applied to the edgés of the capacitor segment of Fig. 7, either radial or axial leads may be applied to it. For example, axial leads 70, 72 witll conventiollal spiral "pig-tail"
ends (not shown) may be soldered, arc-weldecl or conllected b~ ot11er lnealls to the sprayed edge termination layers ~G, 68 al the ends of the wound film capacitor segment ~1, as shown in Fig. 8. Altcrnate]y, radial leads 74, 76 may be soldered, arc-welded or connected by other methods to 1~ the sprayed metallized layers 66, 68 if a radial lead~d capacitor is desired, as shown in Fig. 9.
It will be noted from the foregoing dcscriytion that the number of pleats that may be used to form a capacitor in accor~lance with the previously described embodiment of the present invention is M where M = 5 + (N)4 and N may be 0 or any positive integer. ~he number of pleats M in a capacitor made in accordance with this cmbodiment, therefore, will always be an odd numl)cr.
Other alternate versions of the present invention are shown in llC~S578 ,.. , ~
Figs. 10-12. In Fig. 10 the pleated capacitor segment is formed so that the end pleats 42, 44 have unmetallized strips 46' behind tbese pleats while the center pleat 40 does not. ~he two end pleats 42, 44 extend be-yond the recessed center pleat 40. ~his version is less desiral~le, how-S ever, than the version of :Fig. 3 because it requircs an ;Idclitio~ l stri,~.
Another alternate embodiment is shown in Fig. 11 wherein only one of the end pleats 42 extends beyond the center pleat 40 and the other of the end pleats 44. In this version only one unmetallized strip 46" is required behind the extending end pleat 42, but the charging path is longer -i 10 for this configuration than that of Fig. 3.
~,.' .
Still another alternate embodiment is ~hown in Fig. 12 which differs from the version shown in }~ig. 3 in that intermediate dielectric layers 69, 69' are inserted between alternating groups 71, 73 of pleated layers with the center pleat extended, as in Fig. 3, but with the alternating groups 71, 73 Sacing in opposite directions. If the capacitor of Fig. 12 iæ to be a wound embodiment, the alternating groups 71, 73 of pleated layers which face in opposite directions may be supplied from a different pleated segment supply. Also, it is apparent that the groups of pleated layers shown in Figs. 10 and 11 could be employed u to form a capacitor in accordance with the teaching of Fig. 12 by facing alternating groups of these layers in opposite dircctions ancl b~ scpar-ating these alternating groups with dielectric material.
.
llC}SS78 A portion of another commercially available metallized dielectric strip which may be unwound from a reel, that is suitable for a making of a capacitor in accordance with the present invention is shown in Fig. 13.
~his metallized dielectric strip may also be formed with ~ dielcctric layer 112 of a thin film dielectric material, such ~s polye~tcI, pc)l~r~lopylenc, polystyrene, polycarbonate or other suitable material. A thin metallized electrode layer 114 is applied to the upper surface of the dielectric layer 112 in such a fashion that unmetallized margin areas 116, 118 extend along the longitudinal edges of the strip 110. Iwo thin metallized electrode areas 120, 122 are applied to the lower surface of the dielectric layer 112 so that thc metallized layer 120 extends to the left l~and margin of the layer as shown in Fig. 13, while the metallized layer 122 extends to the right hand margin of the layer. A central unmetallized strip 124 lies between the metallized electrode areas 120, 122.
In the embodiment shown in Fig. 13, the longitudinal dimension of the metallized strip 110 is shown along the arrows 126 wllile the narro~
transverse dimension is shown along the arrows 128. 'This is to allow the capacitor to be pleated along the imaginary line 130 which extends through the length of the unmetallized central strip 124. ~his version of the present invention, however, is also not limited to one in which folding is along longitudinal lines since a capacitor could be made in accordance with this version of the present inventioll by plcating ~long tralls~crse lillcsif the appropriate corrcsponding ~llctallizcd and unmctallizcd areas wcre provided.
A capacitor with a single pleat 140 along linc 130 is sllown in ~ig. 14 which is sliglltly off of tllc center linc 131 of tlle mctallizcd strip 110 with the inside of the pleat 140 in the area being unmetallized. ~he longitudinal ends 148, 150 of the met~sllized strip 110 are arranged in a staggered pattern so that one end 48 extends beyond the other end 150 along the left hand longitudinal edge of the metallized strip because of the off-center pleat of the dielectric layer. ~he extension of tllc cn~ S l~eyon(l tl~c end 150 is preferably at least 0. 020 inches, and tllis extension allows the metallic spray to make contact with at least the upwardly facing electrode area 122 s~own in Fig. 14. The unmetallized margin 116 faces upwardiy while the ~snmetallized margin ll~ faces downwardly when the capacitor segmen'c has been pleated as shown in Fig. 14.
After the capacitor has been processcd to form thc c~paciLor seg-ment shown in ~ig. 14, a number of di~ferent addilional ~rocessing stcps may be undertaken. For example, the pleated capacitor segment of ~ igo 14 could be used to form a capacitor merely by spraying the right and left hand longitudinal edges of the segment wish a metallized spray, such as babbitt or otl~er suital~lc melal, in accol dancc witll con-ventional practice, and then electrical leads cou~ e securcd to them, for e~;ample, by soldering. Alternately, the capacitor segment of :I?ig.
14 could be cut along a transverse line, such as the line 143, and a number of such segments could be stacked u.~on cach otller, with tlle tcrminal end 150 of one capacitor segment being adjacent to l~slt not c~tcnclin~ as far as thc terminal end 14~3' of the capacitor scL~nlcllt ll~at is posi~io1lcd immediately below it, as sho~vn diagrammatic~lly by tl-e (~otted line re-~ -- 17 --ll~S578 presentative of l~ig. 14, and then their ends could l)e sprayed with a met-allized spray and leads could then be secured to thc stacked array of such segments. In conjunction with the presently preferred ernbodiment of the present invention, howevcr, Fig. 14 r~l~rcscnts two laycrs c-f a CapaCi~Ol`
segment formed by winding of the dielectric strip about the lon~itudinal dimension of the strip 110, as shown in ~igs. 15 and 16, to form a wound capacitor. Another version of this capacitor could be achieved, however, by pleating the capacitor segment of Fig. 14 a number of times transversely along transverse fold lines, such as the line 143, or alternately, pleating several times and then completing the segment by Willding thc remaindcr of the length of the dielectric strip.
l he winding of the capacitor segment of Fig. 14 into a wound capacitor may be achieved with various winding techniques, including the use of a split mandrel such as the mandrel 156 of Figs, 15 and 16, which may be removed from the capacitor segmenl after it has becn wo~lnd.
An unmetallized dielectric strip 58 is desirably initiatly wound around the mandrel to protect the metallized electrode areas of the metallized strip 110. ~he winding of the capacitor segment then continues until it is almost completed, at which time an additional unmetallized dielectric ~ strip 150 is then desirably wound into the structure to form an outer pro-tective coating. ~he dielectric strip 160 may also bc heat-scalcd to itself to form a pleated capacitor segment in the manner shown in Fig. 5. ~he .. ,.~,,,, i .
ll~S~i78 removal of the mandrcl 156 from the wound capacitor segment leaves an open-ing in thc unit. ~his opening may be closed by applying pressure, or pressure and heat in accordance with the type of dielectric layer used and conventional manufacturing techniques to the capacitor segnlcnt so that it assumes an oval shape as shown in Fig. 6.
Once the capacitor segment has been wound, a metallized spray may then be directed against the longitudinal edges of the unit in accordance with conventional processing techniques to interconnect the electrode layers along these edges and to provide for the connectioll of clcctrical leads to the unit. The metallized spray will penetrate into the opcn area resulting from the staggering of the ends 148 and 150 on thc left hand longitudinal edge of the capacitor segment, so that the inner electrode provided by the metallized areas 120, 122, is contacted by the sprayed metal particles, but so that the electrode layer 114 is not contacted by such particles, as indicated by the imaginary ylalle lG5 which represents the maximum depth of penetration of the spray particles. The configuration of the present invention thus provides for reliable lead termination at the left hand longitudinal edge of the capacitor segment of Fig. 14 in a manner such tllat metallizecl en~
~ terminations may be employed witl~ a single pleat metalli~e~l CapO-citor. ~ermination to tlle right hand longitudinal cdgc of thc callacitor seg.nent of Fig. 15 is similarly provided by a metallized spray which e~tends over the protruding center pleat 140 to a depth ~VIliCh_ ,~ ~
ilC~S578 is sufficieslt to allow the melallized spray to make good contact to the electrode area 114.
Once the metallic spray has l~een applied to thc ~dgcs of thc capacitor segment either radial or axial leads may be applied to it as previously shown in Figs. 7 and 8.
A portion of another commercially available metallized dielectric strip which may be unwound from a reel, that is suitable for a malcing of a capacitor in accordance with the present invention is shown in Fig. 17. ~his metallized dielectric strip may also be forrned with a dielectric layer 212 of a thin film dielectric material, such as polycster, polypropylene, polystyrene, polycarbonate or other suitable material. A
thin metallized electrode layer 214 is applied to the upper surface of the dielectric layer 212 and a thin metallized electrode layer 220 is applied to the lower surface of the dielectric laycr in sucll a fashioll that unmetallized margin areas 216, 218 extend along the opposite long-itudinal edges of the strip 210 on opposite sides of the strip.
in the embodiment shown in Fig. 17, the longitudinal dimension of the metallized strip 210 is shown along the arrows 226 while the narrow transverse dimension is shown along ti-e arro~vs 2~S. ~he ~ capacitor is pleated along two imaginary lines 230, 232 whicll cxten(l through the length of the strip 210. ~his ~ersion of tl-e present invention, however, is also not limited to one in which folding is along two longitudinal ,~ .
1~5578 lines since a capacitor could be made in accordance ~itll tllis v er;sion of the present invention by pleating along any even number of transverse lines.
A pleated capacitor is shown in Fig. 18 wherein one pleat occurs along the longitudinal line 230 and another pleat occurs along the long-S itudinal lines 232. It is to be noted that pleat lines 230, 232 are spaccd so that the rnargin area 218 e~tends beyond the pleat 242 that I`UIlS ~11Oll~ thc right hand longitudinal edge of the metallized sl:rip 210 of l~ig. 17 with tllc margin area 218 facing downwardly~ 'rhe extension of the margin area 218 beyond the pleats 242 is preferably at least 0.020 inches. In addition, it is noted that the margin area 216 is positioned so that it extencls beyond the pleat 252 that runs along the left hand longiLudinal edge of the met-allized strip and faces upwardly. ~gain, tllc c~:lcnsic)ll of tilC l~al~gi area 215 beyond the pleat 252 is preferably at least 0. 020 inches.
After the capacitor has been processed to form the capacitor seg-ment shown in Fig. 18, a number of different additional processing steps may be undertaken. For example, thc pleated capacitor seglnent of Fig. 18 could be used to form a c~pacitor merely by sp~ g thc rigl~t and left hand longitudinal edges of the segmcnt witl~ a n~ctalli%cd s~t)ra such as babbitt or other suitable metal, in accordance wilh COnVelltiOll practice, and then electrical leads could be secured to them, for ex-ample, by soldering. Alternately, the ca~acilor segment of Fig. 18 could be cut along a transverse line, such as the line 243, and a numl)er ~ "-1 l(~S578 of such segmcnts could l~c staclied upon cach otller, with tht! down-~ardly iacing margin 218 of one capacitor segment being adjacent to and aligned with a corresponding upwardly facing margin 218' of the capacitor segment that is positioned immediately below it, as shown diagrammatically by the dotted line representative of Fig. 18, and then their ends could be sprayed with a metallized spray and leads could then be secured to the stacl;ed array of such segments. In conjullction with the presently preferred embodiment of the present invention, how-ever, Fig. 19 represents two layers of a capacitor segment formed by winding of the dielectric strip about the center of the longitudinal dimen-sion of the strip 210, as shown in Fig. 19, to form a wound capacitor seg-ment. Another version of this ca~citor could l~c achieved, ho~vcver, by pleating, instead of winding, the capacitor segment o~ Fig. 18 a number of times along transverse fold lines such as the line 243. Alternately, the capacitor segment could be ple~ted transversely two or more times about transverse lines, such as the line 243, and then the segment could be completed by winding the remainder of the length of the dielectric strip.
'Ihe winding of the capacitor segment of ~ ig. 18 into a u~und capacitor may be achieved with various winding techniques, including the use of a split mandrel such as the mandrel 25G of Fig. 19, which is removed from the capacitor segment a~ter it has becn wound. An unmet-allized dielectric strip (not shown) may l~e wound arouncl tl~e strllcturc~o , . .
l.l~S'j~8 form an outer protective coating. Ihis dielectric strip may be heat-sealed to itself to form the pleated capacitor segn~ent, as shown in Fig. 6. ~he removal of the mandrel 56 frorn the capacitor segment leaves an opening in the unit. Ihe opening may again be closed by applying pressure, or pressure and heat, in accorclance ~vitll thc t~pc of dielectric layer used and conventional manufacturing techniques to the capacitor segment so that it assumes an oval s)-ape, as shown in Fig. 7.
Once the capacitor segment has been wound, a metal]ized spr~3y may then be directed against the longit-lc3inal cclges of tl-~ unit in accordance with conventional processing techni4ues to intcrconncct the electrode layers along these edges and to provide for the connection of electrical lcads to the unit. Ihe metallized spray will penetrate into the open area between the margin 216 arcas Oll the left hand longitudinal edge of the capacitor segment, as sl-~own dia~rammatically in Fig. 18 to a clepth such as that indicated by lhe plane 2G~), so as to make contact Wit'll the elcctrode area 220. ~he ~lane 2()G indicates the maximum depth that any high velocity spray partic}es will pe~etrate and it may thus be located any place between the end of the margin 216 areas of the metallized strip 210 and tlle edge of the pleat 252.
Accordingly, the metalli%ed spray rnaterial ;'Jill c~-len(l in~o tllc Icf~ _ hanà opening of the capacitor ~etween lhe mar~ 21G ~l~cas far c~-~ough to make contact to the facing metalli~ed clectrodc on the other side c~f ,he dielectric strip, but not so far that it will penetrate through til( 25 t;~ lielectric matcrial at tile picat 252.
11~5578 s ~ern~ination to the right halld longitudinal edge of the capacitor segment of Fig. 18 is similarly provided l)y a metallized spra~ which extends over the margin 218 area to a depth, such as that indicated by the plane 268, which is sufficient to allow the metallized spray to ;~
make good contact to the electrode 214 on tlle inside of the m~rgin 218 area but ~vhich will prevent the penetration of the spray mct;lllic par-ticles through the dielectric at the pleat 242. Ihe location o~ tllc pl~nc 268 may be anywhere between the edges of the pleat 242 and the end of the margin area 218 as long as there is sufficient depth of ~p ray to pro-- 10 vide adequate contact termination to the electrode area 214.. ~he con-~;~ figuration of the present invention thus provides for reliable Icad ter-~;~ mination at the longitudillal edges of tlle ca~acitor SCglllCnt of Fi~. lR
without the necessity of providing unmetallizcd lon~itudinal strips along the inside of the pleats 242, 252, thereby saving considcrable processing expenses in the manufacture of completed capacitors of this type.
Ç
Once the metallic spray has been applied to the edges of the capacitor segment, either radial or axial leads Illay bc ap pliccl to it, again as previously shown ln Figs. 7 and 8.
Another alternate versio,n of the present invention is shown in Fig. 20, wherein two layers of either a wound or a stacked capacitor ,- segment is shown. 'rhis version differs from that sho~n in Fig. 18 ln that intermediate dicleclric ]ayers 2G9, 2G9' are inserlcd bct~ccll ~Itcrltati s ~ , groups 271, 273 of pleated layers of the capacitor segllIcnt ~h ich f~cc in ~: opposite directions. If the capacitor of Fig. 20 is to be a ~voulId embodi-' ~25 ment, the alternating groups 271, 273 of pleated layers \~hicll face in opposite directions may each be supplied from a diffcrent pleated seg-:,~ ~ment supply.
li(~5578 ~he previously described embodiments of the prescnt invention are illustrativc, but not exhaustive, of the various types of configurations that may come within the scope of the present invention. For instance, while winding about the exact center of the dielectric strip is preferred, it is apparent that winding about any number of transversc lines offset from the center, but intermediate the ends of the dielectric strip, arc intended to be included within the scope of the present invention. It is also further apparent that more than two longitudinal pleat lines may be employed in the version shown in Fig. 18 wi~hin the scope of the present invention.
.. . .
` ' ' ~ - 2 5 -
Background of the Invention This application is a division of Canadian Seria1 No. 305,939, filed June 21, 1978.
Electrical capacitors made of thin film dielectric material which ~s metallized on both sides are used in large quantities in electrical devices because of their reliability, their desirable elect-rical characteristics and their relatively low cost. ~nited States Patent No. 2, 470, 826 issued on May 24, 1949 to W. McMahon illus-trates a capacitor in which a double sided metallized dielectric layer is folded an odd number of times in a longitudinal direction. ~he folded dielectric material may then be wound along its lon~iludinal dimension and end terminations may then be applied to it by spraying of metal against the edges of the wound capacitor segment. rrhe type of capacitor described by McMahon patent i~ extremely desirable be-cause substantially all of the dielectric layer of the capacitor is in the electric field and the capacitor may be made without the insertion of an additional dielectric layer in the main body of the capacitor, although a short initial unmetallized dielectric strip and a protective terminating dielectric strip may be employed with the capacitor, if defiired.
~he type of capacitor construction that s envisioned by McMahon patent has a number of decided manufacturing and electrical advantages.
For example, the problem of masking the dielectric layer during elect-rode evaporation when the electrode areas are applied to the film is su~-stantially redused. In addition, no slitting is required as it is during the .~" .
11(~5578 manufacture of conventionat wound ~ilm capacitors. Furthermore.
the capacitance per unit dielectric area is maximized bccause of the substantially full use of the dielectric layer in the electric field. Shorter winding lengths per unit capacitance are thereby required, reducing the winding labor. ~he dielectric lengths can also be calibrated and pre-cut to produce a capacitor of more accurate values. Another advantage of thi~ bpe of capacitor i8 that there are no air layers between the metallized electrodes and the pleated film surfaces and this substantially increases the voltage, for example, one hundred volts or more, at which corona discharge starts, making this capacitor commercially attractive for new applications such as fluorescent lighting circuits. Previously, fifty gauge film thickness or more was required of wound film capacitors to withstand the corona. With the capacitor of the present invention, thirty-two gauge or less dielectric film thickness may be utilized, making ~und film capa-citors economically feasible for such applications.
~ he McMahon patent guggested that leads could be attached to his capacitor by the well-known Schoop process. ~he application of high velocity metallic spray coatings tothe edges of the capacitor described by Mc~qahon is not commercially practical, however, because thc spray wi~ penetr~te through the dielectric area at a pleat and thereby short one electrod~ to the other. If the temperature and pressure of the spray are lowered, penet-ration of the dielectric layers may be reduced but the adhesion of the metallic spray will generally be very poor. Ihe multiple leads suggested in the McMahon patent also are not satisfactory since they tend to tear the dielectric , ll(~S578 material and to make the capacitor bulky ancl inductivc.
In order to solve the above mentioned spray shorting problem at a pleated edge, it has been suggested in Australian Patent No. 159, 958, patented on November 24, 1954 to provide unmetallized dielectric strips behind all of the pleats of a pleated metallized capacitor. While this solution may provide a technically feasible method of attaching leads to apleated metallized dielectric layer capacitor, the number of unmetallized strips that are required on the dielectric layer greatly complicates the manu-facturing proce~ for both the dielectric layer itself and the pleated capacitor product. For example, in a capacitor having five pleats, there must be, in addition to the two unmetallized n~argin areas, five unmetallized strips that run along the entire length of the diclectric malerial,with three of these strips being on one side of the dielectric layer and two of these strips being on the opposite side of the dielectric layer, It iB
apparent that the masking problems and the cost of manufacturing such a specialized item make the solution of the Australian patent commercially unattractive. lhis is especially true since the type of metallized dielectric layer that is u$ed in the capacitor of the present invention, (in which only the margin areas and one unmetallized central strp is required), is readily commercially available. ~urthermore, the employment of an unmetallized strip behind the single pleated capacitor of the McMahon patent, however, -still would not proYide an end termination along the opposite edge of the wound capacitor segment that would allow a metallized spray to be applied to this edge because the ends of the dielectric layer of the McMahon patent at this edge extended beyond both of the melallized electrodes and contact between the metallic spray and the inner e]ectrode area would thereby be prevented .
il~S578 ~}~e leads of the capacitor of the Vnited States Patent No. 3, 854, 075, i ssued l)eceml~cl~ 10, 1974 to John Philip Uhl, were used as mandrels to wind the pleated capacitor segment about the center, in a manner similar to that suggested in United States Patent No. 2, 887, 64g issued May 19, 1959 to Daniel B. Peck. In the Uhl patent, conductive foil tabs were inserted between the leads and the metallized electrode areas to make positive contact with the electrode and to protect the electrode from damage by the leads during winding. However, it has been determined that this construction leads to a higher failure rate than desirable due to opening of the electrode area around the periphery of the metal foil, for reasons which are not completely understood.
~he configuration of the capacitor of the present invention provides a product which has all of the advantages of single pleated, or single pleated and wound, capacitors and also has the added advantage that it may be manufactured with commercially available metallized dielectric material. A further advantage of the present invention is that the same basic starting material may be used to manufacture capacitors having a number of different pleating combinations, which, of course, is not true for the capacitor of the Australian patent, in which each pleat combin-ation requires a specially manufactured die~ectric layer. In addition to the use of the present invention to manufacture wound film capacitors, it is also possible to utilize the invention to produce ceramic capacitors in which the capacitor dielectric material is folded while the ceramic material is still in a "green" state, in a manner similar to that dis-closed in United States Patent No. 3, 223, 494 issued December 14;
1965 to J. W. Crownover.
il~557~
Thus broadly, the invention contemplates an electrical capa-citor segment which comprises a dielectric layer having a center line, a first metallized electrode layer applied to one side of the dielectric layer so that an unmetallized margin extends along each edge of a pair of parallel edges of the dielectric layer, and a second metallized electrode layer applied to the other side of the dielectric layer so that an unmetallized area is located ad-jacent the second metallized electrode layer. The dielectric layer is pleated once along the unmetallized areas off of the center line 10 so that one edge of the margin containing edges extends beyond the other of the edges along the same end of the capacitor segment and metallized spray material is in contact with the second electrode layer.
In a further embodiment the invention contemplates an electri-cal capacitor segment which comprises at least one group of pleated layers comprising a dielectric layer, a first metallized electrode layer applied to one side of the dielectric layer so that an un-metallized margin extends along each edge of a pair of parallel edges of the dielectric layer, a pair of metallized electrode 20 layers on the other side of the dielectric layer, and at least one unmetallized strip that runs between the metallized layers on the other side of the dielectric layer. The dielectric layer is pleated M number of times where M = a ~ (N)b where a is an odd number 3 or greater, and b is an even number 2 or greater, and where N may be zero or any positive integer so that at least one pleat of the pleated dielectric strip extends along one end of the pleated dielectric layer beyond at least one other pleat that extends along the same end as the extending pleat, or pleats, with all of the extending pleats having unmetallized strips behind them 30 along their length. The edges of the metallized dielectric strip which contain the margins extend along the opposite end of the pleated dielectric layer beyond the other ple~ts that extend along the same end as the margin containing edges, wherein the extending pleat or pleats along the one end of the dielectric layer and the margin containing edges along the other end of the dielectric layer are sufficient in length to allow metallized spray material to be sprayed against both of the ends without penetration of the spray far enough to contact any of the pleats except the extending pleat or pleats.
'~7' ~l~SS78 In another broad aspect, the invention comprehends an electrical capacitor segment which comprises at least one group of pleated layers including a dielectric layer, a first metallized electrode layer applied to one side of the dielectric layer so that an unmetallized margin extends along one edgs of a pair of parallel edges of the di-electric layer, and a second metallized electrode layer applied to the other side of the dielectric layer so that an unmetallized margin area extends along the opposite parallel edge of the dielectric layer. The dielectric layer is pleated an even number of times so that the margin areas of the pleated dielectric strip extend along their respective ends of the pleated dielectric layer beyond the other pleats that extend along the same end as the respect`ive margin areas, with the margin areas facing outwardly from adjacent pleats and metallized spray material sprayed against regions of the metallized electrode layers in the vicinity of the margin areas which face inwardly toward adjacent , pleats on both of the ends, but without penetration of the spray far enough to contact any of the pleats.
ll~SS78 Description of the Drawings :
~he present invention is illustrated by reference to the drawings in which:
Fig. 1 is a perspective view of a portion of a metallized dielectric layer which may be used in the construction of a capacitor in accordance with the present invention;
F'ig. 2 is a perspective view of a partially pleated metallized di-s~.' electr~c layer in accordance with Fig. 1 having five pleat lines;
. ~,, - ~
Fig. 3 i8 a perspective view of a fully pleated dielectric layer in accordance with Fig. 1;
Fig. 4 is a perspective view of the fully pleated dielectric layer of Fig. 3 which, in addition, shows a winding mandrel and an unmètallized dielectric insert;
Fig. 5 is a diagrammatic showing of the winding of a ... .
capacitor segment in accordance with the construction of Fig. 4;
Fig. 6 is an end view of a capacitor segmcllt, bcfore le~d attachment, that is wourd in accordance with the showing of Figs.
4 and 5;
Fig. 7 is an end view of the wound capacitor segment of Fig. 6 after it has been pressed into an oval shape;
Fig. 8 is a side view of ~ comptetcd c;~ citor follo~ hc attachment of axial leads;
g .
ll~S578 Fig. 9 is a side view of a completed capacitor following attach-ment of radial leads;
Fig. 10 is a perspective view of an alternate version of a capacitor constructed in accordance with the present invenLion;
Fig. 11 is a perspective view of an additionat alternate embodi-ment:
Fig. 12 is a perspective view of a further alternate embodiment;
Fig. 13 is a perspective view of a portion of a metalliz~d dielectric layer which may be used in the construction of a capacitor in accordance . 10 with the present invention;
~?ig. 14 is a perspective view of a ~ingle pleated dielectric layer in accordance with ~ig. 13;
Fig. 15 is a perspective view of the fully pleated dielectric layer of Fig. 14 which, in addition, shows a winding mandrel and an unn~etallized dielectric insert;
Fig. 16 is a diagrammatic showing of the winding of a capacitor segment in accordance with the construction o Fig. 15;
Fig. 17 is a perspective view of a portion of a metallized dielectric layer which may be used in the construction of a capacitor in accor-dance with the present invention;
Fig. 18 is a perspective view of a plcated metalli%eLl diclc~ctric layer in accordance with Fig. 17 having two pleat lines;
,~
ll(~5S78 ~ ig. 19 is a diagrammatic showing of the winding of a capacitor segment in accordance with the construction of F`ig. 18; and Fig. 20 is a perspective view of an alternate version of a capacitor constructed in accordance with the present inventioll.
~echnical Description of the Invention A portion of a commercially available metallized dielectric strip which may be unwound from a reel, that is suitable for the- mal;ing of a capacitor in accordance with the present invention is shown in Fig 1.
The metallized dielectric strip is formcd with a dielcctric l~ycr 12 oî
a thin film dielectric material, such as polyester, polypropylene, poly-styrene, polycarbonate or other ~suitable material. ~ thin metallized electrode layer 14 i6 applied to the upper surface of the dielectric layer 12 in such a fashion that unmetallized margin areas 16, 18 e~;tend along the longitudinal edges of the strip 10. 'ru~O thin mctallizcd elcctrode areas 20, 22 are applied to the lower surface of the dielectr;c layer 12 so that the metallized layer 20 extends to the left hand margin of the layer as shown in Fig, 1, while the metallized layer 22 extends to the right hand margin of the layer. A central unmetallized stri~ 24 lies between the metallized electrode areas 20, Z2.
In the embodimellt shown in Fig. 1, the longituàill~l dinlellsion of the metallized strip 10 is shown along the arrows ~6 while the narro~
11(~5578 transverse dimension is shown along the arrows 28. ~he capacitor is pleated along the imaginary line 30 which extends through the length of the unmetallized central strip 24. 'rhis version of the prescllt invention, however, is not limited to one in which folding is along longitudinal lines S since a capacitor could be mad~ in accordance with the present invention by pleating along transverse lines if the appropriate corresponding metallized and unmetallized areas were provided.
A partially pleated capacitor is shown in Fig, 2 wherein one pleat occurs along the longitudinal center line 30 and othcr pleats occur along the longitudinal pleat lines 32, 34, 36 and 38. It is to be noted that lines 32, 34, 36 and 3~ are spaced so that the center pleat 40 ex-tends beyond the other pleats 42, 44 that run along the right hand long-itudinal edge of the metallized strip 10 of Fig. 1 so that the inside of the pleat 40 in the area 4G is unmetallized. ~he e~;tension of tlle center pleat 40 beyond the pleats 42, 44 is preferably at lcast 0. 020 inches. In addition, it is noted that the pleats are positioned so that the lOngitudinal ends 48, 50 of the metallized strip 10 are aligned with each other but so that they extend beyond the pleats 52, 54 that run along the left hand longitudinal edge of the metallized strip. Again, the ex-tension of the ends 48, 50 beyond the ple~ts 52, 54 is pleferably at lcasL
0. 020 inches. ~he unmel;allized margin 16, therefore, faccs upwardly while the unmetallized margin 1~ faces downwar-31y whcn thc capacitor ll~SS'7~
segment has been fully pleated as shown in ~ig. 3.
After the capacitor has been proccssed to form the capacitor seg-ment shown in Fig. 3, a number of different additional processing steps may be undertaken. ~or example, the pleated capacitor segment of ~ig. 3 could be used to form a capacitor merely by spraying the right and left hand longitudinal edges of the segment with a metallized spray, such as babbitt or other suitable metal, in accordance with convcntional practice, and then electrical leads could be secured to them, ior e~;ample, by soldering. Alternately, the capacitor segment of ~ig. 3 could be cut along a transverse line, such as the line 43, and a number of such seg-ments could be stacked upon each other, with the terminal end 50 of one capacitor segment being adjacent to and aligned with the terminal cnd 48' of the capacitor segment tl~at is positioned immecliatel~ belo~ it, as ShOWIl diagrammatically by the dotted line representative of ~ig. 3, and tllen their ends could be sprayed with a metallized spray and leads could then be secured to the stacked array OI such segments. In conjuncticn with the p resently pxeferred embodiment of the present invention, however, I;`ig. 3 represents two layers of a capacitor segment formed by ~vindinK of the di-electric strip along the longiLudinal dimellsion of the stril~ 10, ~s sl~o~vn inFigs. 9 and 5, to form a wound capacitor. Another version of this capacitor could be acllieved, however, by pleating the capacitor segment of Fig. 3 a number of times transversely along transverse fold lines such as the linc 43, or alternately pleating several times, and then completing the segment by winding the remainder of the length of the dielectric strip.
~he winding of the ca~)~citor scgmellt Or I;`ig. 3 into a ~ound capacitor may be achieved with various winding techniques, includin~ the use of a removable split mandrel such as the mandrel 5G of Figs. 4 and 5.
An unmetallized dielectric strip 58 is desirably initially wound around the mandrel to protect the metallized electrode areas of the metallized strip 10. Near the completion of winding, an additional unmetallized dielectric strip 60 is desirably wound into the structure to form all outer protective coating. ~he dielectric strip 60 may also be heat-sealed to itself to form the pleated capacitor segment 61 which is shown in Fig. 6. ~he removal of the mandrel 56 from the capacitor segment 61 leaves an opening 62 in the unit. ~he opening 62 may be closed by applying pressure, or pressure and heat, in accordance with the type of dielectric lsccl and convention.~l manufacturing techniques, to the cap~citor segn~cnt ~1 so that it assul~-cs an oval shape as shown in Fig. 7.
Once the capacitor segment of the embodiment of Figs. 4 through 7 has been wound, a metallized spray may then be directed against the longitudinal edges of the unit in accordance witll corlventional processing techniques to intercollncct thc elcc~rode 1a3 cr s alo1l~ tllese edges and to provide for the connection of electrical leads to thc unit.
~Ihe metalllzed spray wilt penetrate into the open area betwecll the ends 48 and 50 on the left hand longitudinal edge of the capacitor segment, as shown diagrammatically in Fig. 3 to a depth such as that indicated -r i~
ll(~S578 by the plane G5. 'rhe plane 65 indicates the maximum depth that any high velocity spray particles will pcnetratc and it l-la~ t]l~lS l~c~ locatcd any place between the ends 48 and 50 of the metallized strip 10 and the edges of the pleats 52, 54. Accordingly, the metallized spray material ;~ will extend into the left hand opening of the capacitor between the ends 48, 50 far enough to make contact to the t~vo facing metallized electrode areas 20, 22, but not so far that it will penetrate through the dielectric material at the pleats 52, 54. ~he configuratioll of tlle present ir~vention thus provides for reliable lead termination at the left hand longitudinal edge of the capacitor segment of Fig. 3 witl~out the necessity of providing unmetallized longitudinal strips along the inside of the pleats 52, 54, thereby saving considerable processing expenses in the manufacture of completed capacitors of this type.
'lermination to the right hand longitudinal edge of the capacitor 1~ segment of Fig. 3 is similarly provided by a metallized spray uh ich ex-tends over the protruding center pleat 40 to a depth~ such as that indicated by the plane 67, which is sufficient to allow the metallized spray to make good contact to the electrode area 14, but which will prevent the penetration of the spray metallic par~iclcs through the diclect-ric at the pleats 42, 44. ~he locationof the plane ~7 may l~e anywhere between the edges of the pleats 42, 44 and the cdge of the yleat 40 as long as there is sufficient depth of spray to provide adcquate contact -termination to the electrode area 14. Again, a considerable cost savin~s ll~SS78 is achieved by thc prescnt invention since thc ~leats 42, 44, lilce lhc pleats 52, 54, did not have to be provided with tl~eir own unmetallized strips. It will be noted in the present invention that only one unmetallized strip 24 is required in the center of the metallized strip 10, and, thus, the same general pattern may be used for various pleat configurations and a ~eparate individually configurat~d mctallizcd st3i1) is nol rcquircd for each pleat pattern.
.
Once the metallic spray has been applied to the edgés of the capacitor segment of Fig. 7, either radial or axial leads may be applied to it. For example, axial leads 70, 72 witll conventiollal spiral "pig-tail"
ends (not shown) may be soldered, arc-weldecl or conllected b~ ot11er lnealls to the sprayed edge termination layers ~G, 68 al the ends of the wound film capacitor segment ~1, as shown in Fig. 8. Altcrnate]y, radial leads 74, 76 may be soldered, arc-welded or connected by other methods to 1~ the sprayed metallized layers 66, 68 if a radial lead~d capacitor is desired, as shown in Fig. 9.
It will be noted from the foregoing dcscriytion that the number of pleats that may be used to form a capacitor in accor~lance with the previously described embodiment of the present invention is M where M = 5 + (N)4 and N may be 0 or any positive integer. ~he number of pleats M in a capacitor made in accordance with this cmbodiment, therefore, will always be an odd numl)cr.
Other alternate versions of the present invention are shown in llC~S578 ,.. , ~
Figs. 10-12. In Fig. 10 the pleated capacitor segment is formed so that the end pleats 42, 44 have unmetallized strips 46' behind tbese pleats while the center pleat 40 does not. ~he two end pleats 42, 44 extend be-yond the recessed center pleat 40. ~his version is less desiral~le, how-S ever, than the version of :Fig. 3 because it requircs an ;Idclitio~ l stri,~.
Another alternate embodiment is shown in Fig. 11 wherein only one of the end pleats 42 extends beyond the center pleat 40 and the other of the end pleats 44. In this version only one unmetallized strip 46" is required behind the extending end pleat 42, but the charging path is longer -i 10 for this configuration than that of Fig. 3.
~,.' .
Still another alternate embodiment is ~hown in Fig. 12 which differs from the version shown in }~ig. 3 in that intermediate dielectric layers 69, 69' are inserted between alternating groups 71, 73 of pleated layers with the center pleat extended, as in Fig. 3, but with the alternating groups 71, 73 Sacing in opposite directions. If the capacitor of Fig. 12 iæ to be a wound embodiment, the alternating groups 71, 73 of pleated layers which face in opposite directions may be supplied from a different pleated segment supply. Also, it is apparent that the groups of pleated layers shown in Figs. 10 and 11 could be employed u to form a capacitor in accordance with the teaching of Fig. 12 by facing alternating groups of these layers in opposite dircctions ancl b~ scpar-ating these alternating groups with dielectric material.
.
llC}SS78 A portion of another commercially available metallized dielectric strip which may be unwound from a reel, that is suitable for a making of a capacitor in accordance with the present invention is shown in Fig. 13.
~his metallized dielectric strip may also be formed with ~ dielcctric layer 112 of a thin film dielectric material, such ~s polye~tcI, pc)l~r~lopylenc, polystyrene, polycarbonate or other suitable material. A thin metallized electrode layer 114 is applied to the upper surface of the dielectric layer 112 in such a fashion that unmetallized margin areas 116, 118 extend along the longitudinal edges of the strip 110. Iwo thin metallized electrode areas 120, 122 are applied to the lower surface of the dielectric layer 112 so that thc metallized layer 120 extends to the left l~and margin of the layer as shown in Fig. 13, while the metallized layer 122 extends to the right hand margin of the layer. A central unmetallized strip 124 lies between the metallized electrode areas 120, 122.
In the embodiment shown in Fig. 13, the longitudinal dimension of the metallized strip 110 is shown along the arrows 126 wllile the narro~
transverse dimension is shown along the arrows 128. 'This is to allow the capacitor to be pleated along the imaginary line 130 which extends through the length of the unmetallized central strip 124. ~his version of the present invention, however, is also not limited to one in which folding is along longitudinal lines since a capacitor could be made in accordance with this version of the present inventioll by plcating ~long tralls~crse lillcsif the appropriate corrcsponding ~llctallizcd and unmctallizcd areas wcre provided.
A capacitor with a single pleat 140 along linc 130 is sllown in ~ig. 14 which is sliglltly off of tllc center linc 131 of tlle mctallizcd strip 110 with the inside of the pleat 140 in the area being unmetallized. ~he longitudinal ends 148, 150 of the met~sllized strip 110 are arranged in a staggered pattern so that one end 48 extends beyond the other end 150 along the left hand longitudinal edge of the metallized strip because of the off-center pleat of the dielectric layer. ~he extension of tllc cn~ S l~eyon(l tl~c end 150 is preferably at least 0. 020 inches, and tllis extension allows the metallic spray to make contact with at least the upwardly facing electrode area 122 s~own in Fig. 14. The unmetallized margin 116 faces upwardiy while the ~snmetallized margin ll~ faces downwardly when the capacitor segmen'c has been pleated as shown in Fig. 14.
After the capacitor has been processcd to form thc c~paciLor seg-ment shown in ~ig. 14, a number of di~ferent addilional ~rocessing stcps may be undertaken. For example, the pleated capacitor segment of ~ igo 14 could be used to form a capacitor merely by spraying the right and left hand longitudinal edges of the segment wish a metallized spray, such as babbitt or otl~er suital~lc melal, in accol dancc witll con-ventional practice, and then electrical leads cou~ e securcd to them, for e~;ample, by soldering. Alternately, the capacitor segment of :I?ig.
14 could be cut along a transverse line, such as the line 143, and a number of such segments could be stacked u.~on cach otller, with tlle tcrminal end 150 of one capacitor segment being adjacent to l~slt not c~tcnclin~ as far as thc terminal end 14~3' of the capacitor scL~nlcllt ll~at is posi~io1lcd immediately below it, as sho~vn diagrammatic~lly by tl-e (~otted line re-~ -- 17 --ll~S578 presentative of l~ig. 14, and then their ends could l)e sprayed with a met-allized spray and leads could then be secured to thc stacked array of such segments. In conjunction with the presently preferred ernbodiment of the present invention, howevcr, Fig. 14 r~l~rcscnts two laycrs c-f a CapaCi~Ol`
segment formed by winding of the dielectric strip about the lon~itudinal dimension of the strip 110, as shown in ~igs. 15 and 16, to form a wound capacitor. Another version of this capacitor could be achieved, however, by pleating the capacitor segment of Fig. 14 a number of times transversely along transverse fold lines, such as the line 143, or alternately, pleating several times and then completing the segment by Willding thc remaindcr of the length of the dielectric strip.
l he winding of the capacitor segment of Fig. 14 into a wound capacitor may be achieved with various winding techniques, including the use of a split mandrel such as the mandrel 156 of Figs, 15 and 16, which may be removed from the capacitor segmenl after it has becn wo~lnd.
An unmetallized dielectric strip 58 is desirably initiatly wound around the mandrel to protect the metallized electrode areas of the metallized strip 110. ~he winding of the capacitor segment then continues until it is almost completed, at which time an additional unmetallized dielectric ~ strip 150 is then desirably wound into the structure to form an outer pro-tective coating. ~he dielectric strip 160 may also bc heat-scalcd to itself to form a pleated capacitor segment in the manner shown in Fig. 5. ~he .. ,.~,,,, i .
ll~S~i78 removal of the mandrcl 156 from the wound capacitor segment leaves an open-ing in thc unit. ~his opening may be closed by applying pressure, or pressure and heat in accordance with the type of dielectric layer used and conventional manufacturing techniques to the capacitor segnlcnt so that it assumes an oval shape as shown in Fig. 6.
Once the capacitor segment has been wound, a metallized spray may then be directed against the longitudinal edges of the unit in accordance with conventional processing techniques to interconnect the electrode layers along these edges and to provide for the connectioll of clcctrical leads to the unit. The metallized spray will penetrate into the opcn area resulting from the staggering of the ends 148 and 150 on thc left hand longitudinal edge of the capacitor segment, so that the inner electrode provided by the metallized areas 120, 122, is contacted by the sprayed metal particles, but so that the electrode layer 114 is not contacted by such particles, as indicated by the imaginary ylalle lG5 which represents the maximum depth of penetration of the spray particles. The configuration of the present invention thus provides for reliable lead termination at the left hand longitudinal edge of the capacitor segment of Fig. 14 in a manner such tllat metallizecl en~
~ terminations may be employed witl~ a single pleat metalli~e~l CapO-citor. ~ermination to tlle right hand longitudinal cdgc of thc callacitor seg.nent of Fig. 15 is similarly provided by a metallized spray which e~tends over the protruding center pleat 140 to a depth ~VIliCh_ ,~ ~
ilC~S578 is sufficieslt to allow the melallized spray to make good contact to the electrode area 114.
Once the metallic spray has l~een applied to thc ~dgcs of thc capacitor segment either radial or axial leads may be applied to it as previously shown in Figs. 7 and 8.
A portion of another commercially available metallized dielectric strip which may be unwound from a reel, that is suitable for a malcing of a capacitor in accordance with the present invention is shown in Fig. 17. ~his metallized dielectric strip may also be forrned with a dielectric layer 212 of a thin film dielectric material, such as polycster, polypropylene, polystyrene, polycarbonate or other suitable material. A
thin metallized electrode layer 214 is applied to the upper surface of the dielectric layer 212 and a thin metallized electrode layer 220 is applied to the lower surface of the dielectric laycr in sucll a fashioll that unmetallized margin areas 216, 218 extend along the opposite long-itudinal edges of the strip 210 on opposite sides of the strip.
in the embodiment shown in Fig. 17, the longitudinal dimension of the metallized strip 210 is shown along the arrows 226 while the narrow transverse dimension is shown along ti-e arro~vs 2~S. ~he ~ capacitor is pleated along two imaginary lines 230, 232 whicll cxten(l through the length of the strip 210. ~his ~ersion of tl-e present invention, however, is also not limited to one in which folding is along two longitudinal ,~ .
1~5578 lines since a capacitor could be made in accordance ~itll tllis v er;sion of the present invention by pleating along any even number of transverse lines.
A pleated capacitor is shown in Fig. 18 wherein one pleat occurs along the longitudinal line 230 and another pleat occurs along the long-S itudinal lines 232. It is to be noted that pleat lines 230, 232 are spaccd so that the rnargin area 218 e~tends beyond the pleat 242 that I`UIlS ~11Oll~ thc right hand longitudinal edge of the metallized sl:rip 210 of l~ig. 17 with tllc margin area 218 facing downwardly~ 'rhe extension of the margin area 218 beyond the pleats 242 is preferably at least 0.020 inches. In addition, it is noted that the margin area 216 is positioned so that it extencls beyond the pleat 252 that runs along the left hand longiLudinal edge of the met-allized strip and faces upwardly. ~gain, tllc c~:lcnsic)ll of tilC l~al~gi area 215 beyond the pleat 252 is preferably at least 0. 020 inches.
After the capacitor has been processed to form the capacitor seg-ment shown in Fig. 18, a number of different additional processing steps may be undertaken. For example, thc pleated capacitor seglnent of Fig. 18 could be used to form a c~pacitor merely by sp~ g thc rigl~t and left hand longitudinal edges of the segmcnt witl~ a n~ctalli%cd s~t)ra such as babbitt or other suitable metal, in accordance wilh COnVelltiOll practice, and then electrical leads could be secured to them, for ex-ample, by soldering. Alternately, the ca~acilor segment of Fig. 18 could be cut along a transverse line, such as the line 243, and a numl)er ~ "-1 l(~S578 of such segmcnts could l~c staclied upon cach otller, with tht! down-~ardly iacing margin 218 of one capacitor segment being adjacent to and aligned with a corresponding upwardly facing margin 218' of the capacitor segment that is positioned immediately below it, as shown diagrammatically by the dotted line representative of Fig. 18, and then their ends could be sprayed with a metallized spray and leads could then be secured to the stacl;ed array of such segments. In conjullction with the presently preferred embodiment of the present invention, how-ever, Fig. 19 represents two layers of a capacitor segment formed by winding of the dielectric strip about the center of the longitudinal dimen-sion of the strip 210, as shown in Fig. 19, to form a wound capacitor seg-ment. Another version of this ca~citor could l~c achieved, ho~vcver, by pleating, instead of winding, the capacitor segment o~ Fig. 18 a number of times along transverse fold lines such as the line 243. Alternately, the capacitor segment could be ple~ted transversely two or more times about transverse lines, such as the line 243, and then the segment could be completed by winding the remainder of the length of the dielectric strip.
'Ihe winding of the capacitor segment of ~ ig. 18 into a u~und capacitor may be achieved with various winding techniques, including the use of a split mandrel such as the mandrel 25G of Fig. 19, which is removed from the capacitor segment a~ter it has becn wound. An unmet-allized dielectric strip (not shown) may l~e wound arouncl tl~e strllcturc~o , . .
l.l~S'j~8 form an outer protective coating. Ihis dielectric strip may be heat-sealed to itself to form the pleated capacitor segn~ent, as shown in Fig. 6. ~he removal of the mandrel 56 frorn the capacitor segment leaves an opening in the unit. Ihe opening may again be closed by applying pressure, or pressure and heat, in accorclance ~vitll thc t~pc of dielectric layer used and conventional manufacturing techniques to the capacitor segment so that it assumes an oval s)-ape, as shown in Fig. 7.
Once the capacitor segment has been wound, a metal]ized spr~3y may then be directed against the longit-lc3inal cclges of tl-~ unit in accordance with conventional processing techni4ues to intcrconncct the electrode layers along these edges and to provide for the connection of electrical lcads to the unit. Ihe metallized spray will penetrate into the open area between the margin 216 arcas Oll the left hand longitudinal edge of the capacitor segment, as sl-~own dia~rammatically in Fig. 18 to a clepth such as that indicated by lhe plane 2G~), so as to make contact Wit'll the elcctrode area 220. ~he ~lane 2()G indicates the maximum depth that any high velocity spray partic}es will pe~etrate and it may thus be located any place between the end of the margin 216 areas of the metallized strip 210 and tlle edge of the pleat 252.
Accordingly, the metalli%ed spray rnaterial ;'Jill c~-len(l in~o tllc Icf~ _ hanà opening of the capacitor ~etween lhe mar~ 21G ~l~cas far c~-~ough to make contact to the facing metalli~ed clectrodc on the other side c~f ,he dielectric strip, but not so far that it will penetrate through til( 25 t;~ lielectric matcrial at tile picat 252.
11~5578 s ~ern~ination to the right halld longitudinal edge of the capacitor segment of Fig. 18 is similarly provided l)y a metallized spra~ which extends over the margin 218 area to a depth, such as that indicated by the plane 268, which is sufficient to allow the metallized spray to ;~
make good contact to the electrode 214 on tlle inside of the m~rgin 218 area but ~vhich will prevent the penetration of the spray mct;lllic par-ticles through the dielectric at the pleat 242. Ihe location o~ tllc pl~nc 268 may be anywhere between the edges of the pleat 242 and the end of the margin area 218 as long as there is sufficient depth of ~p ray to pro-- 10 vide adequate contact termination to the electrode area 214.. ~he con-~;~ figuration of the present invention thus provides for reliable Icad ter-~;~ mination at the longitudillal edges of tlle ca~acitor SCglllCnt of Fi~. lR
without the necessity of providing unmetallizcd lon~itudinal strips along the inside of the pleats 242, 252, thereby saving considcrable processing expenses in the manufacture of completed capacitors of this type.
Ç
Once the metallic spray has been applied to the edges of the capacitor segment, either radial or axial leads Illay bc ap pliccl to it, again as previously shown ln Figs. 7 and 8.
Another alternate versio,n of the present invention is shown in Fig. 20, wherein two layers of either a wound or a stacked capacitor ,- segment is shown. 'rhis version differs from that sho~n in Fig. 18 ln that intermediate dicleclric ]ayers 2G9, 2G9' are inserlcd bct~ccll ~Itcrltati s ~ , groups 271, 273 of pleated layers of the capacitor segllIcnt ~h ich f~cc in ~: opposite directions. If the capacitor of Fig. 20 is to be a ~voulId embodi-' ~25 ment, the alternating groups 271, 273 of pleated layers \~hicll face in opposite directions may each be supplied from a diffcrent pleated seg-:,~ ~ment supply.
li(~5578 ~he previously described embodiments of the prescnt invention are illustrativc, but not exhaustive, of the various types of configurations that may come within the scope of the present invention. For instance, while winding about the exact center of the dielectric strip is preferred, it is apparent that winding about any number of transversc lines offset from the center, but intermediate the ends of the dielectric strip, arc intended to be included within the scope of the present invention. It is also further apparent that more than two longitudinal pleat lines may be employed in the version shown in Fig. 18 wi~hin the scope of the present invention.
.. . .
` ' ' ~ - 2 5 -
Claims (7)
1. An electrical capacitor segment comprising at least one group of pleated layers comprising a dielectric layer, a first metallized electrode layer applied to one side of said dielectric layer so that an unmetallized margin extends along one edge of a pair of parallel edges of said dielectric layer, a second metallized electrode layer applied to the other side of said dielectric layer so that an unmetallized margin area extends along the opposite parallel edge of said dielectric layer, said dielectric layer being pleated an even number of times so that the margin areas of said pleated dielectric strip extend along their respective ends of said pleated dielectric layer beyond the other pleats that extend along the same end as said respective margin areas with said margin areas facing outwardly from adjacent pleats and metallized spray material sprayed against regions of the metallized electrode layers in the vicinity of said margin areas which face inwardly toward adjacent pleats on both of said ends but, without penetration of said spray far enough to contact any of said pleats.
2. An electrical capacitor segment as claimed in Claim 1, wherein said dielectric layer is an elongated layer and said capacitor segment is wound about the center of said di electric strip along the elongated dimension of said layer subsequent to said pleating along longitudinal pleat lines and said metallized sprayed material is applied to the ends of said capacitor after said winding has been completed.
3. An electrical capacitor segment as claimed in Claim 2, wherein said dielectric layer is an elongated layer and said capacitor segment is pleated along lines transverse to the elongated dimension of said layer subsequent to said pleating along longitudinal pleat lines so that each pleat folds the strip in half and said metallized sprayed material is applied to the ends of said capacitor after said transverse pleating has been completed.
4. An electrical capacitor segment as claimed in Claim 1, 2 or 3, wherein a lead is secured to each of said metallized sprayed ends of said capacitor segment.
5. An electrical capacitor comprising a plurality of capacitor segments that are stacked upon each other wherein each capacitor segment comprises a dielectric layer, a first metallized electrode layer applied to one side of said dielectric layer so that an unmetallized margin extends along one edge of a pair of parallel edges of said dielectric layer, a second metallized electrode layer applied to the other side of said dielectric layer so that an unmetallized margin area extends along the opposite parallel edge of said die-lectric layer, said dielectric layer being pleated an even number of times so that the margin areas of said pleated dielectric strip extend along their respective ends of said pleated dielectric layer beyond the other pleats that extend along the same end as said respective margin areas with said margin areas facing outwardly from adjacent pleats, and metallized spray material sprayed against regions of the metallized electrode layers in the vicinity of said margin areas which face inwardly toward adjacent pleats on both of said ends, but without penetration of said spray far enough to contact any of said pleats.
6. An electrical capacitor as claimed in Claim 5 wherein alternating ones of said plurality of capacitor segments face in opposite directions and are separated from their neighboring segments by dielectric material.
7. An electrical capacitor as claimed in Claim 5 wherein a lead is secured to each of said metallized sprayed ends of said capacitor segment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA360,215A CA1105578A (en) | 1977-07-12 | 1980-09-12 | Metallized film capacitors |
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/814,958 US4127891A (en) | 1977-07-12 | 1977-07-12 | Pleated metallized film capacitor with sprayed edge terminations |
| US814,958 | 1977-07-12 | ||
| US814,945 | 1977-07-12 | ||
| US814,954 | 1977-07-12 | ||
| US05/814,954 US4128857A (en) | 1977-07-12 | 1977-07-12 | Pleated metallized film capacitor wound about its center |
| US05/814,945 US4127890A (en) | 1977-07-12 | 1977-07-12 | Single pleat metallized film capacitor with sprayed edge terminations |
| CA305,939A CA1093166A (en) | 1977-07-12 | 1978-06-21 | Metallized film capacitors |
| CA360,215A CA1105578A (en) | 1977-07-12 | 1980-09-12 | Metallized film capacitors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1105578A true CA1105578A (en) | 1981-07-21 |
Family
ID=27508119
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA360,215A Expired CA1105578A (en) | 1977-07-12 | 1980-09-12 | Metallized film capacitors |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1105578A (en) |
-
1980
- 1980-09-12 CA CA360,215A patent/CA1105578A/en not_active Expired
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