US893811A - Electrical condenser. - Google Patents

Description

PATENTED JULY 21, 1908.

G. W. PICKARD. ELECTRICAL CONDENSER.

APPLIGATION FILED NOV.5, 1907.

@....enzeaf whigla fwn/WZ Atty lc.REENLEAF wHrr'rIER PICKARD, or AMESBURY, MASSACHUSETTS.

ELECTRICAL CONDENSER.

Specification of Letters Patent.

Patented July 21, 1908.

Application led November 5, 1907. Serial No. 400,777.

with high-potential currents, as in wirelessy telegraphy and telephony, the object being to make them more durable and 'eiicient; and the invention consists in the disclosure hereinafter rset forth in detail, the Vobject being to prolong the life of such condensers, and to prevent localized heating and destruction due to a blistering or separation between the conducting coating and the dielectric material to which said coating is attached.

Figure 1 is a diagrammatic illustration of the product of the iirst step in the manufacture of the invention; Fig. 2 a similar illusi .1 .of the dielectric, across the gaseous medium tration of the-execution of the second step; and Fig. 3 an illustration of the product of the second step, this being the final product.

In the art of wireless communication, condensers employing solid dielectrics have heretofore in use been vitally defective and short-lived, owing to the action consequent upon the presence of blisters between the conductor and the dielectric material. When the condensers were subjected to the high potential, high frequency currents of this art, more or less extensive blistering occurred, and the electrical discharges occurring between the conducting coating and the surface within such blister, heated the dielectric in the. immediate neighborhood 4to such a degree as not only to greatly reduce the efiiciency of the device, but to shortly destroy it. This has resulted, since condensers are essential inthe practice of this art, in making the. condenser a very weak point in telegraphy transmitting installations, articular y in the casel of ships or insta ations where replacements could not be made within a short'period. It had been supposed that this deleterious action was due chleli to the intervention and retention of air bub lesv or moisture during the process of pasting the all conducting tin-foil coating to theglass dielectric material, which resulted in minutealr or moisture-filled pockets between the two,

and a consequent discontinuity of contact which resulted in localized heating. In accordance with this hypothesis, it has been the practice to exercise great care in so a' plying the tin-foil coating as to have it ma e good continuous contact with the dielectric material so as to avoid the intervention and retention of air-bubbles or concentrated ex cess of the solvent of the cement employed to affix the tin-foil to the dielectric material. Frequently the practice has been tothereafter subject the device to a baking heat to remove as much as possible of the confined gases and solvents.- It has also been roposed, as in United States Patent o. 814,951, to so construct and apply the conducting coatin as to leave -holes or o enings in it, so that w en the device was sulfijected to the baking process, the confined air, etc., might the more readily escape or be removed, as through such openings.- In 'ractice, however, n'one of these expedients as prevented the evils enumerated above. I have investigated this serious question, and have found that the trouble is not chiefly due to the causes heretofore contemplated, but, as I have discovered, the chief cause' is that the action of the high potential currents is not only such as to cause undue heating at blistered points, but to itself cause the production of such blisters, after the manufacture of the device is completed and the same put. into use. care is exercised during manufacture, to exclude the air or excess of moisture, the action of the currents is such as to liberate, after the device is put into use, additional gases, which produce blisters, a resulting discontinuity offco'ntact, and the consequent localized heating, impairment, and `final destruction; I have further observed thatthe action of the currents, during the use of the device, in liberating gases causing blistering, is due simply to the manufacturlng practice of using either as the dielectric base or as the cement or both, materials which were of suc'h nature as to provide a source for the production of gases by the action of the currents.

Thus, hard rubber, or similar organic mate- That is to say, no matter how great tachab 'preserving the proper materials and functions of the dielectric base and conducting coating, none of tige materials can constitute a source of blister-producing gases under the action of the currents employcdin the use'of the device for wireless communication. I have demonstrated by long-continued trials, that it is possible to produce a condenser, with such admirably adaptedv materials as glass for the dielectric base, and a metal for the conducting coating, and with a vbinder lacking in organic matter, moisture, solvents or other gas-yielding com onents which might cause blistering inthe est form of the invention, which 'condenser will have its parts permanently secured together as a whole and in permanent close contact at all points.' I have proved lthat such a condenser not only executes all the desired functions of previous condensers, but also obviates all the troubles With the latter.

Various materials may be employed as the binder, in pursuance of this invention, including those which are self-hardening and settin For example, there may be employe any of the so-called hydraulic ce. ments, such as the dental cement known in trade as Petroid. When glass is used as the dielectric base, I prefer to use the silicate cement known as soluble glass, and called also mineral lime, and also water glass, owing to its solubility in hot Water. Most ofsuch binders, in order to-be non-gas-producing, are inorganic and are lacking in' solvents which might produce excessive amounts of gas under the conditions of use. They vare to .be ap lied to the dielectric base by a brush or Ey immersing the base in a bath of the binder. While the binder is in a soft condition on the base, the conducting coating, which may be tin-foil, is to be applied, so that when the binder sets or hardens, either with or without baking, the conductor will be firmly attached to the base.

One of the classes of binders included within the invention is that which is itself of a metallic or conducting nature, or otherwise suitable for an electrolytic deposit of an electrically conducting material, in addition to its pro erty of being itself permanently atle to the base; or that which itself erforms the function not only of a binder, ut of a conducting coating; all such being substantially inorganic in composition. 4An eX- am le of this is a coating comprising a meta ic paint consisting ofl a powdered conductor such'as graphite or bronze powder and siiicate of sodium, or potash, (Water g'lass) in aqlueous solution, this being particularly wel adapted for use with a glass dielectric base owing to the attachability ol the glass binder to the glass base. ln any case, the metal, (bronze or graphite, etc.,) is

ground exceedingly line, and a hen sufficiently fine and when the paint solution is not too liuid, and the coat applied is sullcicntly thick, this coating mayl suflice as tho only conducting coating. In any case, the mineral lime or water glass, when applied to and set upon the glass base, serves as a means of permanent attachment to and incorporation with the lass; and the metallic paint, when hardened, serves as an admirable base for the electrolytic de osition of a suitablythick or thin metal ic conducting coating, which may be desirable or necessary when the metallic paint alone is unsuitable for use as the complete conductor coating. After the metallic paint is attached to the glass base, as by its silicate constituent, an electrolytic deposit may be made on it of any desirable thickness, such as to insure against blistering or uncturing.

In Fig. 1, J is a jar whicli may be glass, and P the coating of binder or paint, which may be applied by a brush or by immersion of plate J in a bath of the binder. (When the simple mineral lime binder is used, the metallic conductor is smoothly laid over it in the form of sheets, such as tin-foil, and the product baked. In this case, as in the case where metallic silicate paint alone constitutes a sufficient conducting coating, no electrolytic deposit need vbe made. (The silicate element of the metallic paint may be a silicate of sodium solution in water, the strength of the solution being such as to give avsyrupy consistency to the paint, not necessarily too thick, however, as not to be easily spread on the glass base by the brush; Two sldes of the glass Will be` treated in accordance with the invention, to produce a complete condenser. The jalJ of course may be replaced by a plate or other suitable form, the art now employing both plate and jar condensers. After the paint or binder P is applied, the elements J and P together are ba ed inan oven. If sodium or potash silicate solution is employed, the time of such lating may advantageously be about an liour. The temperature of the oven during thisd step about .one hundred degrees centira e. gAfter the step of baking, element of the coatin may be renforced by an electrlyticv deposlt thereon, the metallic element of the paint servin as a base for the deposit. As in Fig. 2, the aked product J, P may be laced in a bath B in a tank T suitthe conducting ably insu ated. The platin bath may be' copperv sulfate solution. T e metallic silicate coating P (the two separate coatings P, P being connected by a lead D) is connected by lead L to one terminal of a suitable electric generator E, the other terminal M being connected to one `anode A (or anodes A,.A1 and A2).in the bath B. The size of the individual anodes and .their distribution with respect to the surfaces to be heated, affords a constant and uniform deposit on .all such surfaces. This step is facilltated by a relative movement of the condenser and anode, which may be obtained by rotating the former with'respect to the latter. As shown, two wooden disks F, G, internally applied to the condenser to su ort it in bath B, are mounted on a rod which is rotated at any desired speed by the application of power to the' ground pulley W. The plating operation ma continue until any desired thickness of p ating is produced, as

at C, Fig. 3. This is simply a' question of economy. The platin is sufficient .to absolutely insure against listering atl the h tem erature of use, even if it be but of slig t thic coating over the metallic aint.

The product, shown in ig. 3, comprises a good conducting coating C which will not blister or deteriorate in use, and which is rirmly attached to vthe base J, by beingincorporated with the metal powder in the paint P, that lpowder bein held-irmly by its associated hardened si icate, and that silicate being firmly attached to the like material, glass, of which J is composed.

1. A condenser consisting of a dielectric base, in combination with a conducting coating, and a composite paint between said elements and having an inorganic substance as one of its constituents and combined with the base and another and conducting metallic constituent combined with the conducting coating.

2. A condenser consisting of a glass base,

a silicate binder incorporated with said base, and a conducting coating incorporated with said binder.

3. A condenser consisting of a glass base, a silicate metallic cement, and an electrolytic deposit of a. conducting coating combined with the metallic element of the cement.

4. An electrical condenser, which consists of a glass base, and a surface coating of a conducting aintincorporated into the material of saidpbase.

5. A condenser comprisinga dielectric base, a binder on the base and having a finelyess, just sufficient to forma completev ree of heat, an

powdered conductor admixed-with it, and an electrolytic deposit of a conducting coating combined with the conducting constituent o the binder.

6. A, condenser. com rising a dielectric base, an inorganic bin er on the base and havin inelypowdered metal admixed with vit,a coating combined with t e metal.

7. A condenser comprising a glass base, a

l paint thereon consisting of a mixture of mmeral lime andiinel -powdered metal, and a metallic electrolytic deposit combined with said metal.

8. The method of producing1 electrical conan electrolytic de osit of a conductingv densers, which consists in ap ying a coating of conducting paint upon t e surface of a glass base, and then subjectin the glass base with the metallic paint applic to a high degrec of. heat.

. 9. The method of `roducing condensers, whichy consists in a' p a cement of min- .erallime and iine y-pow ered metal on `a lass t late, bakm' g the same, and then elecrolytically producing' a metallic deposit upon the cement. v

.10. vThe method of producing electrical condensers,which consists in aplplyin a coating of conducting paint upon t e su ace of a glass base, then subjectln the glass base with the metallic aint ap ed, to a high dethen e ectrolytically proucing a deposit of a metal upon the incorporated conducting paintt 11. An electrical condenser, which consists of a lass base, a binder incorporated with said ase, and an electrical conductor incorporated with said binder.

12. A condenser comprising a glass base and a paint thereon consisting of minera ductor.

paint thereon containin mmer lime containing a iinely powdere metallic conductor,

.lime and 'of a finely powdered metallic conand an electrolytic deposit of a metal com. f

bined with said powdered conductor.

14. Acondenser comprisin aglass base,a

conductmg-paint thereon, an an electrolytic deposit o a conductor combined with the conducting paint.

GREENLEAF WHITTIER PIOKARD.

Witnesses:

EDWARD H. RowELL, MYRA S. RowELL.

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