US2454765A - Electric head lamp projector and incandescent lamp therefor - Google Patents

Description

Filed Sept. 28, 1944- Nov- 30. 1 4 R R. K. BRAUNVSDORFF I 2,454,765

ELECTRIC HEADLAMP PROJECTOR AND INCANDESCENT LAMP THEREFOR 2 Sheets-Sheet 1 REGINALD K. BRAUNSDORFF Nov. 30, 1948. R. K. BRAUNSDORFF.

ELECTRIC HEADLAMP PROJECTOR AND INQANDESCENT LAMP THEREFOR Filed Sept. 28,1944

FIG.

FleQlo.

2 Sheets-Sheet 2 INVENTOR.

REGINALD K BRAUNSDORFF M w m wet 7,.

Patented Nov. 30, 1948 UNITED STATES 2,454,? 65 C J HEA i rj ditQTiiiiA i 'I'NCANDESCENT LAlWP THE REFOR- I Reginald K. Braunsdo'rfi, Eli-stowage, N. 1-; e5 signer to Tung- S0l Lamp WorksJ-nc Newark,- N. J a corporationof Delaware Application September 28, 1e44,- serieiiibsesegiis 3.! Claims. .1 This invention relates to electric headlamp projectors and incandescentlamps therefor.

' A parabolic reflector with a point fig t-source at the focus would give a circular parallel team of reflector diameter. A point source is not available in practice as all conventional filamentspossess mass and size which disturbs such theorectical projection. lhe size of the filament (which includes number of turns, length er barrel and diameter of coil) influences the spot or beam pattern obtained. Different kinds of reflectors have been proposed and various lenses have'been proposed for modifying the beam or batte'rri furnishedby the reflector.

One object of the invention is an incandescent filament lamp for reflector or headlightus'e emb'odying a coil filament of distorted form for oldtaining a headlight beam pattern which appr icimates more nearly the desired pattern thereby minimizing the importance or neeessity'rer the provision of a special modifying lens.

A further object of the invention is anelec trio incandescent lamp of the bove ifidic'atec l character having ac'ontinuo'iis coil filamehtwhich is distorted or irregularly formed at different portions of its length and may be wound en -e single mandrel ate single operation.

A further object or the invention is a coinbified reflector of the conventional paraboiiero'rni and an electric incandescent lamp sourceoftl ie abov'e indicated character mounted in the reflector so as to assist in obtaining the desired beam fiat tern.

Further objects of the invention Will -herein after appear.

For a better understanding of the invention, reference may be had to the accompanying draw ing, forming a part of this application-where Fig. 1 is a View diagrammatically illustrating one embodiment of the invention;

Fig. 2 is a diagrammatic view of another mode fication of the invention v Figs. 3 to 8 are diagrammatic viewsof other modifications of the invention;

Fig. 9 is; a diagrammatic view of an electric incandescent lamp of the generalcharacter shown in Fig.1 mounted in aconventional parabolic reflector, together with a beam pattern which may be approximated by suitably mount-'- A ing the lamp in the" reflector;

Fig. 10 is a similar diagrammaticview of an incandescent lamp of the general character shown in Fig. 2; and l r Fig. 11 is a View of a still fil'i'thei I For vehicle roa'd. lightinggeneralli a beam pattern 18 desired which is cut off in the upper le'ft sectioi ilookingin the direction of travel so as *o Iifififid' lower liglfiit Output in the upper left section, and higher light output inthe upper rig-lit section Two" shapes of such beams are shown drag mriia itically in Figs. 9b 1-01) Brit ridersto'od that these 'beanis' thusschemati "OWIi are iriter ided t illustrate may the shap' a-lld not aeeu reten" to ihd'iait the ei'ac't details of fliebea'lrripattern.

The pattern- Fig. 9b is or sun i'itafitlally' less "depth ontl'i 'lft than it is onthe right; Siic a. Idea-in may be approximated by d of larger coi-ldiameter at its *leftliand and looking dawn the reflector. The filathe r thateiiibodime'fit is er inultipie e011 di parts, there being two such parts 3 and the particular embodiment shown the if) ts 3 and 4 or the mamentnave a; common ax s (Fig; I) Edd-the 1561 1; 3 is lor'l'gl" than the ""e tiriis the length thereof 7, three times" the V din-the larger end 4 of the filamen e iennye lengths er distorted baits or the easiest z be varied to the reqiiire'rnents, fer 'ei'z'a'r'x inle, the large part-4 in 1 sateen; Figs The at 2 e minate in the bulb or enve gne 5 and the lamp" than resumes-in the refle er l Se-sets nfiodu'ce or aeeressinate tne desired-ff r xa'" le', by l ios'itidfiirrg I to h t filament 2 hear ""ga de'fir'iite re atiori t'e' the-fecal point of the raise-ceases for exam-ere, with the focal iioint o'f-th reflector disfaosdintermediate the length of tneeeii 2 and on the common axis thereof. A bam pattern geeeiam like t-at snows in Fig. 96 may be apereetnea naving enlarged part 4 on the right ariart of smaller depth 3' on the left, rocking the difectidii-of the'projcted beam. The enlarged part 4' of the beam pattrn isercedeen by the part 4 or the larger diameter fior'tidii o'f th dis'torted filament'but th epiiesite' side or forward vertical iilan'e 1i sing tnronghtne focal point of thereflector, and-similarly th sinali tairt of the beain' pattern 3 is produced by the small diameter part 3 of the distorted filament but likewise on the opposite side of that vertical plane. As above pointed out, the beam pattern shown in Fig. 9b is not intended to be an exact mathematical illustration of the actual beam produced but is intended as an illustration merely of the general shape contrasting the widely varying parts of the pattern. in Fig. 9 the lamp is mounted in the reflector I with the common axis of the filament 2 disposed substantially horizontal but by orienting the lamp so as to incline this axis of the filament 2 to the horizontal plane the parts 3' and 4 of the beam may be varied in a vertical plane relatively to.

each other, as for example so as to elevate the righthand portion 4 of the beam pattern with respect to the parts 3, thereby bringing the bottom edge of the pattern to approximately the horizontal position. Likewise different beam pattern effects may be obtained by shifting the distorted filament 2 with respect to the focal point of the reflector and by combining these two adjustments other beam pattern effects may be produced.

In the embodiment of Fig. the beam pattern shown in Fig. 19?) has a common bottom cut-off line 6 for both the right and left hand parts of the beam, with the filament l disposed substantially horizontal. A beam of this general shape, looking in the direction of the beam projection, may be approximated by distorting the shape of the filament l as shown in Figs. 2 and 10a. In this embodiment the filament coil is also provided with different coil diameter parts at its ends, the right-hand part 8 of the filament being of small diameter, while the part 9 on the left is of relatively larger diameter, but here the axes of the two filament parts 8 and 9 are relatively offset with the edges of the turns of the parts 8 and 9 being disposed in line on one side. In Fig. 2 the axis of the part 9 of the filament is shown in broken lines while the axis of the part 8 of smaller diameter is illustrated in a dot-and-dash line. The part 9 of the filament assists the reflector in producing the part 9"of the beam pattern, while the part 8 assists in producing the part 8 of the beam pattern (Fig. 10b); The focal point of the reflector I may be disposed roughly midway the length of the filament coil 7 and between thev axes of the coil parts 9 and 9 and by the use of a parabolic reflector I or reflector generally of that construction or of the conventional type, the beam pattern parts corresponding to the particular parts 8 and 9 of the filament are produced on the opposite sides of the vertical plane passing through the axis ofthe reflector. This pattern corresponds generally to the positioningof the filament about the focal point as described, with the axis of the filament part 9 disposed below the axis of the filament part 8, namely with the filament part 9 being predominantly below the horizontal plane through the axis of the reflector, while the filament part 8 is generally symmetrical with respect to that plane. The pattern may be varied by mounting the filament in the reflector so as to have the axes of the filament parts offset from each other in any desired direction.

The pattern shown in Fig. 10b may be varied by changing the filament 1 relatively to the focal point, that is by changing the vertical or horizontal positioning with respect to the focal point or by a combination of these adjustments In the particular embodiment illustrated or by rotation of the bulb 5 about its axis in the reflector. In the particular embodiment shown the length of the small diameter part 8 is greater than the length of the large diameter part 9 and also in this particular embodiment the part B has roughly twice the number of turns and is roughly twice the length of the large diameter part 9 but it is understood that the number of turns of each of the parts 8 and 9 may be Varied to suit any particular requirements.

In the embodiments illustrated in Figs. 1, 2, 9 and 10, the diameter of the filament parts 3 and 8 is roughly one-third the diameter of the larger diameter parts 4 and 9 respectively of the filaments. Also in the particular embodiments shown the filaments are constructed with steps in diameter, as distinguished from tapered coils with a uniform variation in diameter from one end to the other. But it is understood that certain advantages of the invention may be obtained with variations in the structure of the filaments, the relative arrangement thereof with respect to themselves and to the focal point of the reflector, etc.

The filament embodiments of Figs. 3 to 8 show different forms of continuous coil distorted fila ments. In Fig. 3 the parts 8 and 9 of the filament 1 are like the embodiment of Fig. 2 shown of uniform diameter turns but are reversely positioned with respect to that illustrated in Fig. 2. In Fig. 3 the axis of the part 8 which is illustrated in dot and dash lines is illustrated to be displaced with respect to the axis of the part 9 which is illustrated in broken lines, which is in reverse position of that shown in Fig.2.

In the embodiment of Fig. 4 the continuous coil distorted filament Ill has its turns gradually increasing in diameter from the small end II to the large end 12 and the increase in diameter is not uniform but the increase in diameter is according to a mathematical curve as indicated by the tangent CD touching the rearward edges of the filament turns. The axis of the filament I0 is shown in the dot-and-dash line.

In the embodiment of Fig. 5 the distorted filament I3 is provided with turns gradually increasing in diameter from the small end M to the large end l5 and here the filament is unsymmetrical with respect to the axis EF of the small and of the filament, the axis FG of the filament l3 being inclined to the axis EF and the rear edges of the turns forming the filament coil are tangent to the vertical transverse plane parallel with the axis EF. This is in contrast with the symmetrical filament ID of Fig. 4 whose turns are formed symmetrically about the axis EF of the smaller end of the filament. In the em bodiment of Fig. 5 the axes EF and GF are illustrated as being in a plane parallel to the plane determined by the legs A and B of the filament. In the embodiments of Figs. 2 and 3 the axes of the filament parts 8 and 9 are also disposed in a plane parallel with the legs A and B. In the embodiment of Fig. 6 the continuous coil distorted filament I6 is formed of two parts I! and i8 which parts are in turn formed of turns of uniform diameter similarly to the embodiments of Figs. 1, 2 and 3. Instead, however of the axes of the filament parts I1 and I8 being coincident as in Fig. 1, they are offset from each other but in a specifically different manner as shown by the lefthandp'art of Fig. 6, so that as viewed in the righthand portion of Fig. 6 the axes of the two parts I! and i8 appear to be coincident. Here the axis of the small diameter eateries:

5. part H of thefilament is parallel to the plane determined by the legs A and B andlikewise th'e axis of the large part IS. The centers of the parts H and I 8 are indicated respectivelyat and K in projectionto the left of Fig. 6.

In the embodiment of Fig. 7 the filament 20 is provided with a small diameter part 2| and a larger diameter part 22 at the endswith an intermediate part 23. The part 2| is of uniform diameter and the part -22 is-of uniform diameter but the intermediate part 23 is of varying diam--'" eter so as to merge the end parts 21, 22 gradually into each'other. In the embodiment ofFig; 8 the filament 25 is formed of a small diameteripart 26 and a larger diameter part 2Trespectivelyformed atthe ends. The small-diameter part 261s 'of uriiform diameter-turns. The larger diameter *part 2'! is formed with fiat-sided turns, the flat side being indicatedat 21'. Assuming "the mounting is such that the fiat side-of the large diameter part .2! is on the under side of the filament -25 shown in Fig. 8, theaxes of the parts 26'and 21 are displaced from each other in a vertical plane. In therighthand portion ofFig. 8 these axes'appear coincident. The sides of the turns of the small diameter part 26 on one side are level with the surface of the fiat side 21' of the large diameter turns, that is the plane including the surfaces of thefiatsides 21' of the part 2 istangent to the surfaces of the turns forming the coil part 26. The ends of the axes of the two coil portions arexindicated at H and K.

It is understood that the continuous coil 'dis torted filaments of Figs. 3. to 8 are'mounte-d in a reflector of suitable type, asfor example, one of the general parabolic type illustrated'by the numeral l in Figs. 9 and 10. In each modification difiierent forms of beam patterns may be obtained by mounting the filament or lamp bulb 5 in the reflector in such a manner as to obtain or approximate the desired shape pattern. As with the modifications of Figs. 1 and 2 (Figs. 9 and 10) different shape beams may be obtained by mounting the filaments of each of the modifications 3 to 8 in different positions relatively to the focal point of the reflector and the axis of the beam pattern maybe adjusted. as may be desired by rotating the lamp bulb-5 within the reflector to obtain the desired orientation of the pattern.

In the particular embodiments illustrated I have shown bulbs -5 embodying only aisingle distorted filament but in some cases it may be desired to mount two of these distorted filaments in the same bulb with the bulb mounted in the reflector so as to obtain a special beam pattern formed by the combined lighting effect of the two or more distorted filaments thus mounted with respect to the focal point of the reflector or special beams from the individual filaments. Such a lamp bulb is illustrated in Fig. 11 wherein a bulb is shown embodying two independently mounted continuous coil distorted filaments, being similar to the filamentl of Fig; 1. It is'understood that the lamp bulb here shown is mounted in a reflector of any suitable type, as for example, of the parabolic type indicated at l in Figs. 9 and 10 with the two distorted filaments .30 and 31 positioned with reference to the focal point of the reflector as may be desired to obtain or approximate the beam pattern desired.

Thus this invention makes it possible to obtain a beam pattern which is substantially different from the beam pattern furnished by the conVentional filament lamps and accordingly an-initial beam distribution unassisted by lensactionds obtained which, together with the particular re fiectorused, is either sufiicienttogivethedesired beam pattern, "or less lens action is required to give the exact beam 'patterndesired, thereby simplifying' headlamp structures. In the particular embodiment shown in Figs, 1, '2, 9 and 10 the filament parts 3 and 8 of smaller diameter are somewhat smaller than the diameters of the coil filaments conventionally used in vehicle headlights, w'hilethe filamentp'arts 4 and 9 are of substantially larger diameter.

The different embodiments of the invention indicate the wide variety of possible shapes of'continuouscoil-distorted filaments and the possibilities of construction and flexibility afforded 'by the invention. "Any part of the coil filament may be specially'constructed as for example, with a hat spot (Fig. 8) or with a raised section atsome indivldilal'poin't Within the total coillength. The mass or space occupied by the filament maybe varied together with its shape at difierent points inorderto obtain the effect desired in the project-ion with parabolic reflectors and the like. As above indicated the inherenterrorin projection maybe met by some special lens in the area which gave trouble in the projectedbeam but with my invention compensation may be made or approximated in the particular continuous coil filament shape and in the particular position in which it is mounted in the bulb. Moreover, it is entirely practicable to form continuous coil filaments of the shapes indicated'by forming them'on -simi larly shaped mandrels.

In each of the Figures *1 to 8 the portion of the figure to the left is an approximate correct pro ject'ion of the largeend of the filament with certain of the turnsoi the coil omitted in certain cases-tosimplify the drawings.

Iclaim:

1. In an electric headlamp, a reflector, an in candescent lamp in thereflector having a lighting beam filament of the continuous coil type, said filament having its end portions formed of different coil diameters and the whole filament being positioned in the vicinity of the focal point of the reflector and at an angle to the axisof the lamp with the different diameter end portions thereof disposed on the opposite sides of the re fiector axis.

2. In an electric headlamp, a reflector, an incandescent lamp having a'lighting beam filament of the coil type, "said filament having its end portions formed of different coildiameters and the whole filament being" positioned in the reflector in the vicinity of its focal point and at an angle to the axis of the lamp with the diffierent diameter end portions thereof disposed on the opposite sides of the reflector axis, and said small diameter part having a larger number of turns than the number of turns inthe larger diameter partlw i3. In an electric headlamp, a reflector, an incandescent lamp having a lighting beam filament of the coil type and mounted in said reflector, said filament l'having end portions of different "c'oikdiameters and the whole filamentibeing posiitioned in the" vicinity of the focal point of the reflector with 'thefoc'altpoint disposed at the axis of the smaller coil section, said filament portions having a common axisand disposed at an angle to .the 'axis of the lamp with the different diameter end portions thereof disposed on the opposite sidesof thereflectoraxis.

:4. In an electric headlamp, a reflector, an ining beam filament of the coil type, said filament having its end portions formed of different coil diameters and the whole filament being positioned in the vicinity of the focal point of the reflector, said filament parts having their axes offset with the different diameter end portions thereof disposed on the opposite sides of the reflector axis.

. 5. In an electric headlamp, a reflector, an incandescent lamp therein having a lighting beam filament of the coil type, said filament having its end portions formed of different coil diameters and the whole filament being positioned in the vicinity of the focal point of the reflector, said filament portions having their axes offset vertically with the different diameter end portions thereof disposed on the opposite sides ofthe reflector axis.

6. In an electric headlamp, a reflector and an incandescent lamp source having a lighting beam filament of the coil type disposed in the vicinity of the focal point of the reflector with the barrel of the coil disposed at anangle to the axis of the headlamp, the coils at certain parts of the filament being of different diameters with different diameter portions disposed on the opposite sides of the axis of the lamp so as to provide a filament at the focal point which is unsymmetrical with respect to the axis of the lamp.

'7. In an electric headlamp, a reflector generally of the parabolic type and an electric incandescent lamp source having a lighting beam filament of the coil type with the whole thereof being disposed at or in the vicinity of the focal point of the reflecton said filament crossing theaxis of the reflector at the focal point, said filament having portions on the opposite sides of thereflector axis which are unsymmetrically distorted with respect to each other so as to give a distorted drive beam pattern.

8. In an electric headlamp, a reflector generally of the parabolic type, an incandescent lamp having a lighting beam filament of the continuous coil type with the axis of the lamp being coincident with the axis of the reflector, the whole of said filament crossing the axis of the reflector at the'focal point and having end portions of different coil diameters with one end portion of the filament disposed on one side of the vertical axial plane passing through the focal point of the reflector and the other end portion of the filament disposed on the other side thereof to produce a projected driving beam pattern of laterally elongated form with the lefthand end of the pattern being of substantially less depth than the right-hand end thereof.

9. An electric incandescent filament lam for projectors comprising an elongated coil lighting beam filament provided with turns of different diameters at certain parts thereof with the whole thereof disposed in the vicinity of a point of the lamp axis, and said coil being disposed at an angle to, and passing through, the axis of the lamp with the turns of different diameters making the filament unsymmetrical with respect to such axis.

10. An electric incandescent lamp for electric projectors embodying an elongated coil lighting beam filament embodying at least two parts havbeam filament embodying at least two longitudi-' nally disposed parts having turns of different diameters with the whole thereof disposed in the vicinity of a point of the lamp axis, said parts having a common axis angularly disposed with respect to the axis of the lamp, said parts making the filament unsymmetrical with respect to the axis of the lamp.

12. An electric incandescent lamp for electric projectors embodying an elongated coil filament embodying at least two parts having turns of different diameters, the axis of one of said parts being offset with respect to the axis of the other.

13. An electric incandescent lamp for electric projectors embodying an elongated coil filament embodying at least two parts having turns of different diameters, said parts having axes offset along the axis of the lamp.

1 14. An electric incandescent lamp for electric projectors embodying an elongated coil filament embodying at least two parts having turns of different diameters, said parts having axes offset along the axis of the lamp with the edges of the turns of the parts forming on one side a straight line.

15. An electric incandescent filament lamp for projectors comprising an elongated coil lighting beam filament whose turns increase in diameter from one end to the other, said coil filament passing through, and being disposed at an angle to, the axis of the lamp.

16. In an incandescent lamp for electric headlamps, a continuous coil driving beam filament whose turns differ in diameter from one end to the other with the rate of change in diameter increasing from one turn to the next.

17. In an incandescent electric lamp for headlamps, a continuous coil lighting beam filament whose turns increase in diameter from one end to the other in a uniform manner, said coil filament passing through, and being disposed at an angle to, the axis of the lamp.

18. In an electric incandescent lamp for headlamps, a continuous coil lighting beam filament having at least two parts differing in diameter of turns, the axes of the two parts being displaced in a plane at right angles to the axis of the lamp;

19. In an electric incandescent lamp for headlamps, a continuous coil filament whose end portions are formed of uniform and different diameters with an intermediate portion of turn diameters merging into the two end parts.

20. In an electric incandescent lamp for headlamps, a continuous coil filament having at least two parts of different turn diameters and one of said parts being formed with a flat side.

' 21. In an electric incandescent lamp for projector headlamps, a continuous coil lighting beam filament of elongated form disposed crosswise of the lamp axis but having all of its parts disposed closely to the point of the axis at the crossing point, said driving filament having end portions of different coil diameters with said portions disposed on'the opposite side of the axis to provide an elongated driving beam pattern with one end thereof of substantially lesser depth than that of the other end.

' 22. An electric incandescent lamp for headlamps embodying an elongated coil lighting beam filament having at least two longitudinally spaced parts of turns of different diameters, said parts being disposed on opposite sides of a plane including the axis of the lamp, with the whole thereof being disposed in the vicinity of a point of the lamp axis.

23. In an electric headlamp for automobiles, a reflector, an incandescent lighting beam filament of the continuous coil type concentrated at the focal point of the reflector to produce a driving beam with a minimum of difiusion due to displacement of filament parts from the focal point, said filament having its end portions formed of difierent coil diameters with one end of the filamerit disposed on one side of the vertical axial plane through the focal point and the other end of the filament disposed on the other side thereof.

24. In an electric headlamp, a reflector general- 1y cf the parabolic type, a lighting beam incandescent filament of the continuous coil type in said reflector, said filament crossing the axis of the reflector at the focal point and having end portions of different coil diameters with at least the extreme end portions of the filament disposed on opposite sides of the vertical axial plane passing through the focal point of the reflector to produce a projected driving beam pattern of laterally elongated form with one end of the pattern being of substantially less depth than the other end thereof.

25. In an electric headlamp, a reflector generally of the parabolic type, a coiled incandescent filament light source located in the vicinity of the focal point of the reflector and having portions thereof of substantially difierent coil diameters with at least the extreme end parts of said source disposed on opposite sides of the vertical axial plane passing through the focal point of the reflector to produce a projected passing beam pattern of a laterally elongated form with the righthand end of the pattern looking in the direction of travel being of substantial depth to light up the righthand side of the road to a considerable vertical depth and with the lefthand end of the pattern being of substantially less depth to minimize glare to approaching drivers.

26. An electric incandescent projector lamp comprising a reflector and an elongated coil as the light source having turns of different diameters at certain parts thereof, said coil being disposed in the vicinity of the focal point of the reflector and transversely of and unsymmetrical to the longitudinal axis thereof.

27. An electric incandescent lamp for projectors having an axial lamp mount to produce a focused light beam, comprising an elongated coiled filament disposed transversely of the base of said lamp, said filament having turns of different diameters at certain parts thereof and unsymmetrically located relative to the longitudinal axis of the base.

28. An electric incandescent lamp for projectors, comprising an elongated coiled filament with the turns increasing in diameter from one end to the other, said filament disposed transversely of the axis of the base of the bulb and in the vicinity of a point thereon whereby said lamp cooperates with the projector toproduce a beam of light of elongated cross-section wherein one end portion thereof is substantially deeper than the remaining portion.

29. An incandescent projector lamp having a coiled incandescent filament, said filament comprising at least two portions of different diameter. whose longitudinal axes are substantially parallel and disposed transversely of the longitudinal axis of the base part which extends through the focal point of the projector, said filament aXes being adjacent said focal point whereby an unsymmetrical focused light beam is produced.

30. An electric light projector in combination a reflector, and an elongated light source disposed transversely of the longitudinal axis of the reflector, said light source having different size light producing areas at different parts thereof to produce a beam of light unsymmetrical to the axis.

31. An electric light projector comprising a reflector, an elongated filament in said reflector disposed transversely of the longitudinal axis there of, said filament having turns of different diameters at different parts thereof and supporting and electrical connecting means for the filament extending through and positioned in the rear of the reflector for connection to an electric circuit.

REGINALD K. BRAUNSDORFF.

file of this patent! UNITED STATES PATENTS Number Name Date 379,770 Edison Mar. 20, 1888 1,157,995 Mack-ay Oct. 26, 1915 1,402,374 Papini Jan. 3, 1922 1,436,807 Jaeger Nov. 28, 1922 1,640,288 Nicholson Aug. 23, 1927 1,704,467 Engle Mar. 5, 1929 1,707,540 Riedel Apr. 2, 1929 1,811,782 Duncan, Jr June 23, 1931 1,859,601 Rice May 24, 1932 2,067,129 Marden Jan. 5, 1937 2,128,461 Johnson Aug. 30, 1938 FOREIGN PATENTS Number Country Date 55,038 Denmark July 18, 1938 200,850 Great Britain July 17, 1923 228,366 Great Britain Feb. 5, 1925 246,504 Great Britain May 13, 1926 297,052 Great Britain July 24, 1928 454,129 France Apr. 21, 1913 648,455 France Aug. 13, 1928

Images