US1410077A - Automobile headlight - Google Patents

Description

E. Ek PECK. AUTOMOBILE HEADLIGHT.

APPLICATION FILED APR.2o,-19`2.1

Patented Mar. 21, 1922.

' the road in ront of the automobile.

EDWARD E. rncx, or Los ANGELES, CALIFORNIA.

AU'roiuoBiLn HEADLIGHT.

Specification ofLetters'Patexit.

Appiieatiomiiea April 2o, 192i. serial yiin'1--ie2mis- To all whom-t may concern:

.Be it known that I, EDWARD E. PEGK, a citizen of the United States, residing at Los An `eles, county of Los Angeles, and State of alifornia, have invented a new and useful Improvement in` Automobile Headlights, of which the following is a specification.A

For the'purposebfallowing the operation of vehicles at night, it is common practice to suppl 4headlights which 'illuminate Such headlights are now commonly operated by electric power and-it is possible by the use of suitable reflectors or other concentrating devices to provide avery lintense illumina.-- tion. Various attempts have been made l be thrown exclusively on the surface of the -light the illumination street 'as in the ordinary forms of headlane which passes through the center of the headlight is quite considerable. This illumination above the horizontal plane is practically valueless to the driver ofthe vehicleand it is a source of great danger as it tends-to blind the drivers of vehicles approaching in'the opposite direction.

Legislation has beenl assed in inany States in the attempt to eliminate the glaring headlight nuisance and various devices are nowin use which are designed to overcomethis diiculty. p

It is an object of my invention to provide a headlight in which the illumination above a horizontal' plane is `substantially eliminated.

. Further objects and advantages will bemade evident' hereinafter.

l Referring to 'the drawing which isfor illustrative purposesonly,

Fig. 1 is 'across section-through a headlight embodying my invention.

Fig. 2 is a section onanlenlarged scale on a` plane represented by the line 2-2 of Fig. 1.

' n the form of the invention shown, 11

is a luminous source,`siich5 for example asan incandescent. light with avery small.

filament. 12 is a reflector which 'may be an Vellipsoid or a paraboloid, 13 isa lamp casing, 14 is a barrel and 15 is a lens mounted above a horizontal Patented Mar. 21, 1922.

11 and thelens 15 is a light intercepter 20.` This intercepter may have` a curved. i

edge as shown at 21 in Fig. 2. The lens 15 4is smaller Vin 'diameter than the reflector 12. The luminous source 11 'is s o placed i a-nd the reflector 12 isxsoformed that the light striking onthe surface of the reflecvtor is thrownin a converging beam on lthe inner surface of the lens 15, the direction of typical rays being indicated by the lines a-a and b-ZL with the luminous source at its focus or a parabola with the 'luminous source in front y, of the focus. to control this illumination so that it Will dii'ce an-approximately parallel beam. Vitli the highcandle power incandescent lamps now available, thisv beam is very intense. The standard type of automobile headlight has a reflector 'whose surface Vis symmetri- .cal about the light axis of the headlight and the .beam pnojected isalso symmetrical about that axis. As a result as much light u .This may be accomplished by making the-section of reflector an ellipse is thrown above this axis as below and varii -oiis inventors have provided intercepters or diffusers to cut down the glare above this axis. -Inpractice I prefer to so shape ther'.

reflector 12 and the lens 15 that the beam of -light from the lens 15 is focused at a point some distance infront of the headlight, the

light thereafter spreading to light up the roadway. The degree of such spreading maybe varied by different forms of lens 15. The intercepter 20 cuts off' the upper portion of the projected beam beyond this forward focal point. The lens 15 of course also has a second focal`point and' is so lo- -cated that this f ocal point is between the lamp 11 and the lens 15. I have found, by placing the intercepter 20`at this point, that the lower edge ofthe shadow 'producedby the intercepter may be made veryfsharp.

The `,reasonfor this can be understoodi-f we consider that in any commercial headlight, in whichV an incandescent lamp and a sheet metal reflector are used,the li ht rays do not follow any exact system. T e lamp does not constitute a..point source andthe the lmetousea .20 in the focal plane reflector, due to the re uirements y'of cheapmanufacture is not of t e exact theoretical shape. There follows a dispersion or jumbling of the rays. Also we have not onllyl7 the reflected rays shown at a, b and d, whic in the construction' shown converge, but we also have the direct rays c which are diver ent. Now, if we place an intercepter in t,lens 15 or directly in front or behind the lens, the shadow ofthis intercepter will have a very indistinct edge. There will, in fact, be as many shadows as there are systems of rays and the projected shadow for the reflected rays may bevwidely displaced from the shadow for the direct rays. Now absolute sharpness at the composite shadows edge requires ythat all the projected shadows4 shall coincide at each and every distance in frontof the headli ht. This condition canot be obtained wit commercial lamps and reflectors due to the lack of a point source, errors of focus, and imperfections of manufacture, and it certainly cannot be obtained where both divergent direct light and convergent reflected light is concerned as.

in the construction shown. This absolute sharpness can be approximated closely, how.- ever, if the intercepter 20 is placed in the focal plane ofthe lens 15. If so laced, any rays which cross each other at t e edge of the intercepter 20 will be parallel to each other after they leave the lens 15. In other words, the edge of the direct li ht shadow will beat y and the edge of't e reflected light shadow will be at :v and these two shadows will'register vwithin the distance .az-y of each other vat any distance infront of the headlight, if, for` example, the lens 15 is three inches indiameter the distance --y will be about l inches, with the proportions shown, which means that at any distance such, for example, as fifty feet in `front ofthe headlight the eye will pass from a position receiving all t e light into a position of full shadow by a Avertical movement of 1i inches.

The result is a sharpness of shadows edge which allows the headlight to be tip ed so that the rays mand y are directed si htly downwardly as*l the with the assurance t at practically no light will be thrown above the horizontal plane; a I am also able by placing the intercepter of the lens 15 to cut the intercepter considerably below the optical axis of the peadlight and still preserve the sharpness o shadow desired. This allows greater proportion of the total light with a consequent gain in efficiency.

The intercepter 20 is shown as locatedin vthe focal plane and entirely below the axis of the lens inside the lamp casing.' In practice the intercepter thus prevents practleally or substantiallyltheclower half of the circle of light projectedjfrom the reflector from leave the hea lightl reaching the upper half ofthe lens, and by locatin the intercepter at substantially the inner ocus of the lens the line of division between light and shadow issharply defined and no glare above this line is produced.

nieretheory as I have fully and conclusively demonstrated by actual experimentthat the edgeof the projected shadow is very sharp with the intercepter 2O in or near the focal plane of the lens and that this sharpness is destroyed if it is moved for any considerable distance-out of this plane.

I claim as my invention: v

1. In a lamp of the character disclose the combination including a source of light, a lens having its rearward focal plane within the lamp, a reflector having one focus within the lamp and the other exterior of the lamp in front of the lens anddirecting the refiected light toward the lens in non-intersecting planes and alight intercepter substantially at the rearfocal plane of the lens and below the axis of the lamp Hand intercepting substantially the lower half of the light beam.

2.*In a lamp ofthe character disclosed, the combination including la source of li ht, a reflector directing a. cone of light or wardly, a lens positioned to truncate said light cone and having its rearward focal plane forwardly of the light source, and a light intercepter substantially at said rearward focal plane and constructed to intercept the beam transversely below thel axis of the lenspreventing a portion ofthe light reaching ythe lens.

3. In a lamp of the character disclosed,' the combination including a lamp housing, a source of light in the rear portion of the housing, a reflector behind the light source directing the cone of light forwardly, alens axially alincd with the light source and positioned at the forward end of the housing to truncate the light cone, said lens having its rearward focal plane forwardly'of the light source, and a light intercepter substantially at said rear focal plane and below the axis of the lamp, said intercepter extending to lthe wall of the housing to form an imperhalf of the reflector.

5. In a lamp of the character disclosed the combination including a bi-convex lens, a light source rearwardly of the rear focal plane o f the lens, and a. reector behind the l7`o The above advantages are not based on lao lgh source, all axiell alined, and a light` lens andthe intercepter functioning to preintercepte'r substantial y at the rear focal vent the ray'slfrolngthe lower half of the replane and below the axis of the lens, the `reflector from reaching the lens. 10 flector functioning to reflect light rays di- In testimon whereof, I have hereunto set;l Y 5 rectl to the lens 1n non-intersecting planes, my hand at lios Angeles, California, this the lens functioning to converge both the 14th day of April, 1921, direct and reflected light rays beyond the EDWARD PECK.

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