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Publication numberUS1637445 A
Publication typeGrant
Publication dateAug 2, 1927
Filing dateOct 11, 1923
Publication numberUS 1637445 A, US 1637445A, US-A-1637445, US1637445 A, US1637445A
InventorsAlbert W. Franklin
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Variable mica condenses
US 1637445 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Aug. 2, 1927. 1, 7, 5


ATTORNEY Patented Aug. 2, 1927.



Application filed October 11, 1923. Serial No. 667,879.

This invention relates to improvements in that class of apparatus used for varying the capacity in an electric circuit, commonly known as variable condensers.

.One of the objects of the invention is to provide a device for this purpose that is compact in form, easily assembled and operated, not readily liable to derangement and which is capable of producing minute variations between zero and full capacity.

Another purpose is to produce an apparatus having a sealed chamber containing a liquid conductor and contacting element free from dust, corrosion or coatings ordinarily gathered by exposure to the air, thereby assuring proper and uniform electrical contact and consequently attaining a predetermined result in accordance with the position of its parts.

A further object is to secure intimate contact between the conductors and the intervening dielectric or insulating material, thus avoiding variation in capacity resulting from irregularity of the spaces so often found between these elements of condensers of the prior art. The conductor being liquid, its physical area may change-to vary the capacity, it contacting readily with and tak iug the form of the container ,or enclosure, in filling interstices and preventing air gaps,

etc. f

A further aim is in the provision of an apparatus of unusual simplicity, well suited for use in connection with the various forms of telephony now in common vogue.

These and analogous aims and objects are accomplished by the novel construction, combination and arrangement of parts hereinafter fully described and illustrated in the accompanying drawing, forming a material part of this disclosure, and in which Figure 1 is a partial side elevational, partial sectional view of an embodiment of the invention as completely assembled.

Figure 2 is a plan view of the dielectric chamber looking from the open inner side.

Figure 3 is a similar view of the chamber cover.

Figure 4 is a vertical transverse sectional view showing a modified form of chamber complete with its mountings, drawn to a. smaller scale.

Figure 5 is an interior plan view of one of the chamber sides.

Figure 6 is a like view of the other side of the chamber.

By further reference to the drawing it will be seen that Fig. 1 illustrates a common application ofthe invention, the numeral 10 designatin a conventional type of radio base boarc and 11 the front panel of the same. i

Fixed on the board 10 is a base plate 12 made of non-conducting material and secured on its upper surface are two uprights 13 and 14 having oppositely bent feet 15 and 1 6 clamped to thebase plate by bolts 17 and 18; the bolt heads are entered in counterbored openings in the xbottom of the plate d h i bQdit P idfid w th amp u 19 and 20 above which. a re thumb nuts 21 an 22eoes u ipgfiin c mbinati t b a omm n pe of bind P The upperends of the uprights are bored n ter, t e upri h 1. rotatably pper-t g a 2 2 4 ma ing upright W 5 i: m un ed n i a spi d e .4., extending Hawaiian peninaintbdimp at 11 n in st? it exten in @ndris a knu n b 25 he breast ever 26e s orm wi h bstsll s ie -27, whichi qy-be g ad t 3 l .-9 ll i 9Q:W h' r 'P QV-Q m rk .Q&$l Q-W ,1.tbe-ia eiof h ment-'1 Th St m te a -wv th a s ud 28 aving a thln disc -likegheadigfland a, single radial plate-like ;extension 30.;."' I

A cipcular member ,3-1 o f dielectric material, ,a s .or sinilap substance of the Q LD g oup, is moulded. concentrically on the disc 29 and plate 30st -;t. ha t their ree s ir inn e -are fiush an level, firmly cu n th 'pa -t h ni The member 31 has, .ai-raised.. peripheral ea 2 and i rment seat i i3,-' il s he ght sas im in a ren w-c mbe 3 of nlive a h except f r an emeat a ep esr vhi'sh ts a reserv rt a q antity of mercury 36 therein.

The mercury may be entered when the member is held level, and sealed by a mica plate 37 held on the seat 33 by a suitable adhesive and clamped by the raised element 38 of a disc 39 made of similar material as the member 31, fitted to the ring 32 and held this space however being slightly above the level of the mercury in the reservoir 35 in the mating element.

The disc 39 is moulded on the thin, enlarged head 42of a cylindrical'extension 43 '1 of the spindle 24, said extension 43 and stud 28 having distinct shoulders abutting the inner faces of the uprights 13 and14 to prevent end motion of the device.

It willnow be apparent that upon turning the knob and graduated disc 27 integral with it,'th spindle 24 will convey rotary motion to-the disc 39, which motion is transmitted by the screws 40 to the chambered member 31, stud 28an'd stem 23. 3

"It will also be obvious that as the chambered plateis rotated, ever solittle, that the mercury in the reservoir 35 will flow out into'the space 34, making co'ntact with the plate 3Q, and covering a'portion of the mica plate 3", and when the condenser is in an elec tricalcii'cuit causing an induced current to pass through'the-plate in'extent depending on the amount of rotation-imparted, the. mercury also making a directelect rical contact with the disc 29gand arm 7303 T If connected in electrical circuit by the binding posts l7 and'=18,- with" the mercury 36 at the lowest pointl'in' tlie"reservoir 35, there will no capacity fie'ct, therebe ing no conductor opposite the reservoir and the dial should register Zero capacity. YT f rotated 1S0 tlie'maximum capacity is'freached, the-mercury having run outof 'its rese'rvoir by gravity into' the"'chamber' lgt forming a thin sheet Whose 'are'a'is'q lalzit leastto the area of the opposed conductor 36f. -=j

In the modification shown in F 1', 5 and6 a quite similar-device is shown, except that bot-hplates'are variable in area, the upright supports and 51 carrying shouldered spindles 52-and 53 having heads 54'and 55 cross shaped and arrangedins't aggered relation in dielectric elements 56 and 57, to avoid 'capacity'efiect.

Tliesei elements having between them a 'mica plat-e58, presentspaces- 59'and 60, the

latter beingsealed', as'at 61, byT shaped inserts such'as asphaltum'or pitch and have,

in their inner adjacent sides, chambers 62 and 63 containing mercury, as at 64 and 65, the same being entered through openings 66 and 67' eventually plugged by screws 68 and 69.

\Vhen the condenser is connected in an electrical circuit it will be apparent that when the device is partially rotated, causing the mercury to flow into the spaces 59 and 60, induction will take place through the plate 58 in the manner before described.

The foregoing disclosure is to be.regarded as descriptive and illustrative only, and not as restrictive or limitati've of the invention, of which obviouslyan' embodiment may be constructed including many modifications withoutdeparting from the general scope herein indicated and denoted in the appended claims.

An instance of another embodimentwhich I have discovered \vorksvery Well is one in which the area-of theinercury conductors or plates may be changedlto vary'the-capacity of the condenser by varying the space or distance between the dielectric and the casing thus raising the level'of'the mercury in its chambers and in that way eliminating the reservoir; i

Having thus described myinventiomwhat I claim as new and; desire to' secure by Letters Paten't,is:'" E i 1. A variable condenser, comprising liquid condenserplates of variable area, separated by a dielectric plate, said condenser plates mounted in =die1ecric containers, said'dielectric plate and containersfsec'ured to each other, and shafts placed in tandem relation formingelec'tri'calj conductors 'from each of the condenser plates. v 1

In a variable condenser, a dielectric base, supports securedt her'to, shafts intande'in' relation jo'i'irnal'ecb in said" supports, a dielectric plate secu'red' to'ea'ch of said shafts, one of said plates formed with a flange to overlie the other and having a crescent shaped We'll 'form'edi'n it,"both' of said plates recessed" for 'hoiising"-"eii' 1arged portions on said shafts, enlarged substantially circular recesses in each of said plates 'a thin dielect'ric' plate secured'be'tween the first mentioned plates, and variable "Imercury condenser plates in thespaces' formed between said three dielectric platesQ v Signed 'at New York, in the county of New York and State -o'f-New York, this 6th day of October, A. D. 1923.



Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4624140 *Jul 30, 1984Nov 25, 1986Optima Systems, Inc.Liquid medium capacitive displacement sensor
US8510966Mar 30, 2011Aug 20, 2013Jack A. EkchianMethod and apparatus for hysteresis reduction in displacement of sensors
U.S. Classification361/292, 361/278
Cooperative ClassificationH01G5/12