US1306511A - Reflector - Google Patents

Description

A. AMES, JR.

Patented J 11116 10, 1919.

6 SHEETS-SHEET l.

A. AMES, JR.

REFLECTOR. APLICATION FILED ]AN.17|19l6- I Patented June 10, 1 919.'

6 SHEETS-SHEET 2.

A. AMES JR.

REFLECTOR.

APPLICATION FILEDVJ'AN. 17. me. 1 ,306,51 1 Patented June 10', 1919.

e SHEETS-SHEET s.

1/7 /&

A. AMES, JR. REFLECTOR.

APPLICATION FILED JAN. 17. l9l6.

Patented June 10, 1919.

6 SHEETS-SHEET 5 A. AMES, JR.

REFLECTOR.

APPLICATION FILED JAN. 17. l9l6- 1,306,511. I PgtentedJune10J919.

6 SHEETSSHEET 6- UNITED STATES PAT N OFFICE.

ADE LBERT AMES, JR", OF TEWKESBURY, MASSACHUSETTS.

REFLECTOR. I

To all whom it may concern:

Be it known that I, ADELBERT AMEs, J r., a citizen of the United States, residing at Tewkesbury, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Reflectors, of which the following is a disadvantage of using beam of light is: first, that the distant road specification, reference being had therein to the accompanying drawlngs.

-My invention relates to llghts and light- .ing wherever control of light rays is desired,

and is particularly useful when applied to headlights such as are used on automob les, interurban cars and other vehicles.

The discomfort and danger caused to users of the highway by the use at nlght of ordinary headlights on vehicles is well known. There is also a considerable inconvenience and danger to the driver of the vehicle.

The rays from a light source placed at the focus of the commonly used parabolic reflector go out in a bundle of parallelrays and light up the distant road, without llghting up, however, the road in the near or middle distance. It is a common practice of the users of such headlights to obtain illumination of the nearer parts of the road by putting the light source out of focus, either in front or behind, and thus change the reflected rays from a narrow parallel bundle to a broad diverging one. If the light source is put behind the focus, this effect, is produced by the rays striking the reflector at such an angle that they flare out directly. If the light source is put in front of the focus the rays strike the reflector at such an angle that they are reflected back across each other, and then flare out. The such a diverging is not properly illuminated and fast driving is very dangerous to the user; second, part of the diverging bundle of rays radiate upward and are blinding to the other users of the highway, and are wasted for roadway illumination purposes. If the light is put in the focus, and the distant road illuminated, danger arises owing to the fact that the driver cannot see the near road.

To meet these difliculties numerous States have passed laws requiring that the illumination from headlights shall light up the road in a predetermined manner.

One ofthe principal objects of my in- Specification of Letters Patent. Patented J 11 10, 1919, Application filed January 17, 1916. Serial No. 72,503.

vention, as applied to he illights, is to provide means to do away wi the above mentioned dangers and nuisances, utilize all of the radiant light energy, and meet the different laws of the different States: for example, a headlight, first, which will light up the road at a distance as far as possible ahead of the car; second, which will light up all the road and sides of the road be tween such a distant point and a point a few feet ahead of the car; rthird, which will light up said road and sides of road to any extent an'dintensity that may be required; fourth, to accomplish the foregoing purposes in such a manner that no glare or blinding effect is caused to approaching pedestrians or drivers, or other users of the highway; fifth, to conserve and utilize all the radiant energy of the lamp.

I obtain this result by combining portions of reflectors formed by the revolutions of suitable conic sections having a common axis and a substantially comanon focus, with a source of light placed substantially at said focus.

Another object of my invention .is to provide a reflector to give control of the distri: bution and the concentration of rays from a light source, and may be said to comprise aseries of concentric rings of elliptical or hyperbolic surfaces, having a common axis and suitable foci, as will clearly appear hereinafter.

Other objects and the means of attaining them will appear hereinafter.

In the drawings, most of which are diagrammatic, illustrating the principle of my invention and the best mode now known to me of embodying the same in various operative structures, which are adapted to project the light in the manner indicated, to overcome the said objections, and to conform to legal requirement,

Figure 1 shows in elevation rays emanating from an automobile headlight having an elliptical reflector above, and a para bolic reflector below;

reflector above, and a hyperbolic reflector below;

Fig. 10 shows the combination of a parabolic reflector below, and an elliptical reflector above the common axls;

Fig. 11 shows a parabolic reflector below,

and a compound elliptical reflector above said axis;

Fig. 12 shows a parabolic reflector above, and a hyperbolic reflector below the axis;

Figs. 13 and 14 are a. plan and a front view of headlights having an elliptical reiliector above, and a parabolic reflector be Figs. 15 and 16 are like views where the reflectors are respectively parabolic above and hyperbolic below; I

Fig. 17 shows a parabolic reflector above and a compound hyperbolic reflector below the axis;

Fig. 18 a parabolic reflector above, and a compound hyperbolic reflector below the axis, the arrangement of the parts of the compound surfaces being reversed from that appearing in Fig. 17;

Fig. 19 an elliptical reflector above, and a hyperbolic reflector below the common axis; while Fig. 20 is an elevation of a headlight having a compound elliptical reflector above, and a compound hyperbolic reflector below a common axis;

Figs. 21 and 22 show how a parabolic mirror may be made to embody my invention by mounting therein another reflector of suitable conic section.

A half parabolic reflector 1, Fig. .10, below and half elliptical reflector 2 above a common axis 3-3, have a common focus indicated by plane f, where a suitable light source 4 is placed. This common axis is, throughout the description in this application, assumed to be horizontal with the ground G, as is shown in Fig. 1.

In accordance with the laws of reflection, all of the rays from the focus 4, Fig. 10,

reflector by the half parabolic reflector 1,

are projected forward above the ground, in the form of a half cylinder of parallel rays 5, Figs. 1, 2, 4 and 10, and light up the distant road; while the rays 7 from the half elliptical reflector 2 pass through its other conjugate focus 6 at any point on the common axi 33, whence the rays 7 spread out in the form of a half cone 7, Fig. 5, below the axis, and illuminate a portion of the roadway in the rear of the distant portion illuminated by the concentrated beam from the parabolic reflector 1. It is, of course, well known and understood that all rays of 1 light located at one focus of an elliptical nary elliptical reflector as illustrated in.

Figs. 1, 2 and 10, which has heretofore been proposed, has been found to be unsatisfactory. The present invention overcomes the said difliculty as will now be described.

In order to illuminate the near and intermediate and distant road to the same extent, the rays which light up the distant road must be more concentrated than those which light up the near road. To accomplish this I provide a half parabolic reflector 10, Fig. 11, below, with a compound elliptical reflector 11 above the common axis, as shown in Fig. 11. It is made up of a series of elliptical'surfaces as ab, b0 and 0d, all of which have a common focus with the parabolic reflector at the light source 4; the other foci of the elliptical surfaces ab, 60 and 0d being forward of the common focus, at the various points 12, 13, 14, in the common axis 33 from which it is desired to surfaces from their foci, when the forward foci are changed. The area of the surface ab, which reflects the light through the most distant focus 12, and lights up the most distant parts of the road, is made greater than the area of the surface 60, which lights up the nearer road. The same would be true of the relative areas of be and 04. By the proper choice of these relative areas, the distant and near, road can be illuminated to any desired relative degree.

Substantially the same result as is obtained by the reflectors shown in Fig. 1 may be attained by a half parabolic reflector 15, Fig. 12, above, with a half hyperbolic reflector 16 below the common axis 33, see also Figs. 6, 7 and 7*. They have a common focus at 4, where the light source is placed. The half parabolic reflector 15 throws out a bundle of parallel light rays 17, as above described, and lights up the distant road. The half hyperbolic reflector 16 is so shaped that its other focus is on the horizontal axis 3, 3, say at 18, behind the focus 4, at a distance necessary to give a considerable spread oflight; the light rays 19 from common focus 4 being reflected forward and clownward by the hyperbolic reflector 16, in a line which, if continued rearwardly, would pass through the focus 18. Figs. 6, 7 and 7 make plain the resulting illumination.

The hyperbolic reflector can be so proportioned as to give a fairly wide spread of light but it is not adapted to distribute the light so as to illuminate the near and intermediate portions of the roadway uniformly. I therefore make no claim to this arrangement.

In order to illuminate the near and intermediate portions of the roadway uniformly I propose to modify thehalf hyperbolic reflector in a manner similar to that above described in connection with the modified elliptical reflector. I also accomplish this, by combining with a half parabolic reflector 20, Fig. 17, above, a compound hyperbolic reflector 21 below, the common axis 3, 3; the half hyperbolic reflector in this case, instead of being asurface with one outside rear focus, is made up of a series of concentric rings of hyperbolic surfaces, ab, b0 and 0d, all of which have one focus 4 at the light source, and the other at different points as 22, 23, 24 respectively, on the common axis 3, 3, to the rear.

The surfaces ofthese hyperbolic rings may be made continuous by changing the difierences of the distances of all the points in the several hyperbolic surfaces from their foci when the outside rear foci is changed.

It can be seen that by using the proper proportions of hyperbolic surfaces with properly chosen outside foci, the light can be distributed and concentrated as desired, with the same result that was seen in connection with what appears in Figs. 8 and 9.

Where, as is frequently the case, slightly diverging rather than the parallel rays projected by aparabolic reflector are desired to light up the distant road, a half elliptical reflector 25, Fig. 19, above, with a hyperbolic reflector 26, below a common axis 3, 3,

may be used. Both surfaces have a common focus 4; the second focus of the ellipse being on the axis in front, as at 27; while the second focus of the hyperbola is on the axis behind at 28. While for convenience I have shown the hyperbolic reflector as a simple reflector it is to be understood that according to the present invention the hyperbolic reflector would be modified as in Fig. 17.

The advantage flowing from this combination is, that it is often desirable that the illumination used for lighting up the road at a distance, should be a diverging and not a parallel beam, in order that there may be a broader illumination at that point. This can be accomplished by placing the outside forward focus 27 of the half elliptical reflector at such a point that the desired spread is obtained.

In order that the rays from the elliptical reflector above mentioned may appear to be distributed from several rather than one point or focus in front of the common focus,

a compound elliptical reflector 11, Fig. 11, already described, may be combined with a simple hyperbolic reflector, or, as shown in Fig. 20, with compound hyperbolic reflector 26' below the common axis 3, 3, to give the desired breadth or distribution of illumination.

In the compound form of elliptical, and of hyperbolic reflector, the ring surfaces, whose outer foci are nearest to the light source focus, can be placed inside or outside of those ring surfaces whose outer foci are more distant from the light source. For instance, in Fig. 17, the surface cal of the hyperbola whose rear focus 24 is nearest to the light source 4, is continuous to and outside the other surfaces 07), and ba, whose rear foci are at 23 and 22, respectively; while in Fig. 18, the surface ad has its rear focus at 28, which is farther from the light source 4, than the foci 29 and 30, of thesurfaces 0b and ba which lie inside of the surface ed.

One method I employ, of rigidly combining the two half reflectors by means of flanges at their adjacent edges, is evident in Figs. '13, 14, 15 and 16 of the drawings. Each reflector is made in one piece, flanged and secured to its neighbor by screw nuts. Although I prefer to use half reflectors and deem them a part of my-invention, I do not thereby preclude myself from making the combined reflectors all in one piece.

lVith these various combinations of reflectors, a screen 40 or small mirror, or frosting on the bulb, may he put in front and abm'e the light source 4, as is seen in Fig. 10, and, consequently, none of the rays will be projected above the level of the top of the lamp, if the axis of the lamp is placed in a horizontal position.

lVhile I have described the compound elliptical and hyperbolic half reflectors as being made up of rings of true elliptical and hyperbolic surfaces, plainly any surfaces approximating the form of these surfaces that will produce the above described effects, are contemplated by my invention.

The modified conic sections in Figs. 8, 9, 11, 17 18, 20, etc., that is the line of intersection between the modified elliptical or hyperbolic reflector and a plane containing the axis of the reflector, is obviously generated by shifting the secondary focus, that is the forward focus of the ellipse or the rear focus of the hyperbola, by steps as the conic section is generated. For example, in Fig. 11 the modified elliptical section abcd is generated by describing the portion ab of the modified elliptical section about the foci 4 and 12, then shifting the secondary focus to 13 and describing the portion bc about the foci 4 and 1.3, then shifting the secondary focus to 14 and describing the portion cd about the foci l and 14. Thus, in Fig. 11 the modified'elliptical section is generated in three stages by shifting the secondary focus two steps. However, it will of course be understood that the modified conic section may be generated in any desired numlber of stages and that the secondary focus may be shifted any desired distance between each of the stages. The limiting condition would be an infinite number of stages and infinitesimal steps between stages, which would involve gradually shifting the secondary focus as the modified conic section is generated. In other words the bands ab, bc, cd, etc., may if desired be made infinitesimally narrow.

As an attachment for the ordinary automobile headlight having a reflector 50, Fig. 21, of parabolic form, I provide in the position as shown in Fig. 1, a section of a reflector 11 of compound elliptical form, as described, say 11 of Fig. 11, having one focus at 4: in common with that of the parabolic reflector. Such a half compound elliptical reflector will project the rays downward and illuminate the road as desired, as above described. Instead of such reflector 11, there may be attached, in azposition as shown in Fig. 22, below the axis 3, 3, a compound byperbolic reflector 21, Fig. 17, as above described, and having one focus at at in common with that of the parabolic reflector, so that it will hang below the electric light bulb. Such a half hyperbolic or compound hyperbolic reflector will project the rays downward and illuminate the road as desired, as described above. By the words parabolic reflector as above used, I intend to cover any form of reflector, as, for instance, a; Man gin mirror, which projects approximately parallel rays.

For the sake of simplification in my descriptions, I have described my combinations of reflectors of different curvatures as being exactly half revolutions joinedftogether at their horizontal meridian. The fact is, however, that the areas of these surfaces may be combined in varying proportions. For example, the advantage of departing from the combination of two half reflectors for use in an automobile headlight, will be evident where one "of the reflectors is parabolic, and it is desirable to increase the amount of light in the parallel beam relative to that in the diverging beam. In such a case, the parabolic reflector may be a section greater than half a revolution, say three-quarters, and the other surface less than half a revolution, say one-quarter.

However, it will be understood from the foregoing description and the accompanying claims that while I have illustrated ordinary elliptical and hyperbolic reflectors in certain of the figures more fully to illustrate the dificulties my invention is intended to overcome, I make no claim to the use of such reflectors. On the contrary I claim only such reflectors and similar reflectors when modified as herein disclosed.

It is to be understood that such words as horizontal, vertical, upward, outward, etc., are used throughout the specification and claims merely for convenience in referring to relative locations and directions and that my invention is not limited to headlights em ployed solely in the position herein described. On the contrary, the invention is applicable wherever it is desired to project a beam of light sharply defined on at least one side. I contemplate, for example, applying my invention to search lights employed to illuminate buildings and thelike.

Having described various and equivalent forms of structure, illustrating the principles of my invention and desiring to protect the same in the broadest manner legally possible,

What I claim is:

1. Projection apparatus comprising a light source, and a reflector havmg a contour divided into a plurality of transverse portions, the respective portions being formed by the revolution of conic sections, each transverse portion having a plurality of foci, and one focus of each transverse portion being positioned at the source of light and the other foci of the transverse portions being displaced along the axis or axes of the reflector in such manner that light may be projected to distant, near and intermediate portions of a roadway.

2. Projection apparatus comprising a reflector having a contour formed by the revolution of a modified conic section, the modified conic section having a plurality of foci and being formed by maintaining one focus of the section fixed and axially varying the position of the other focus as the curve of the conic section is described, and a light source positioned at the fixed focus, the modified curvature of the conic section being such that a divergent beam of light having a regular angular variation of intensity may be projected.

3. Projection apparatus comprising a light source, a concave reflector on one side of a horizontal plane passing through the light source, the reflector being positioned with respect to the light source in such manner as to project a concentrated beam of light horizontally, and a reflector on the other side of said plane divided into a plurality of transverse portions, the respective transverse portions having contours formed by the revolution of conic sections, each transverse portion having a plurality of foci, one focus of each transverse portion being positioned at the source of light and the other foci of the portions bein displaced along the axis or axes of the re ector in such manner that divergent beams of light may be projected into the region below the said horizontal plane.

4. Projection apparatus comprising I a light source, a substantially hemi-paraboloidal reflector positioned on one side of a horizontal plane passing through the light source with its axis substantially in said horizontal plane, and a reflector on the 0th r side of said plane having a contour forme by the revolution of a modified conic section, the modified conic section having a plurality of foci and being formed by maintainingone focus of the conic section fixed and axially varying the position of the other focus as the curve of the section is described, the latter reflector being positioned with its fixed foci at the light source in such manner, and the modified conic curvature being such, that a divergent beam of light may be projected downwardly.

5. Projection apparatus comprising a light source, a reflector above a horizontal downwardly, and a substantiall plane passing through the light source having a contour divided into a plurality of transverse being curves, one focus of each transverse portion being positioned at the source of light and the other foci of the transverse portions be-' ing displaced different distances from the fixed foci along the axis or axes of the reflector and being displaced in such manner that a divergent beam of light is projected hemi-paraboloidal reflector positioned elow said plane with its focus at the source of light for projecting a concentrated beam of light horizontally. I

In testimony whereof I hereunto aflix my signature in the presence of two witnesses.

ADELBERT AMES, JR. Witnesses:

A. I. CRAWFORD,

SHEDD.

portions, therespective portionsformed by the revolution of elliptical.

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