US659353A

US659353A - Headlight-lens.

Info

Publication number: US659353A
Application number: US1632200A
Authority: US
Inventors: Julian H Pitkin
Original assignee: Individual
Current assignee: Individual
Priority date: 1900-05-11
Filing date: 1900-05-11
Publication date: 1900-10-09
Anticipated expiration: 1917-10-09

Description

Patented 061.9, |900.

3 shuts-Sheet 2.

Y J. H. PITKIN.

HEADLI'GHT Lens. (Applimion med my 11, 1900.,v

(No M'ocllel.)

Patented Oct. 9, |900.

.. J. H.' PIT-KIN.,`

H EADLIGHT LENS. (Application led May 1}, 1900.)

(No Model.)

3 sheath-shea: 3.

f Kc? 6am/@A 5 als s, v

' [UNITED STATES-f" .PATENT CE1-Inns JULIAN-rn. PITKIN, or CHICAGO, ILLINOIS; Y i\ H EADeLr-GHT- LNS;

SPECIFICATION' forming pare of Letters Patentino. 659.353, dated oceoeer e, 1900.

A y Application tiled May 1l, 1900. Serial No.-16,822. (No modell To all whom it may concern: l extended 'laterally-confined path along the Be it known that I, JULIAN H. PITKIN, of ground. and the angle as between the prisms Chicago, in the county of Cook and State of themselves'is also varied, all as will hereins 5 Illinois, have invented certain new and use- 'after more clearly appear. f 5 ful Improvements in lieadlight-Lenses,l of v In abicycle headlight-lens there are emwhich the following is a specification. I ployed a series of prisms arranged concen- My invention relates to lenses for v'ehiclctrically and which occupy substantially the headlights, and has for its object to provide wholeof the surface of the lens,.the prisms 6o such a device that will assemble and conne beging arranged close to each other. The rays 1o the rays of light in a beam that shall be lim- 'of light proceeding from the flame diverge or ited laterally to a narrow path and extend spread, and when these divergent rays pass along the-ground from a point in close proxthrough the plane emergent surfaces of adjaimity to the source of light to a point considcent prisms it is found that this divergence 65 erably distant therefrom without at the same is not corrected and the refracted rays 4of light 'I5 time crossing the line of vision. from adjacent prisms intercept each other, v My improved lens is primarily intended'for` thus producing a pen-umbra or shadow at the use on bicycle-lamps, where a thoronghlysides of the lin'e of intersection*ioovercome---v illuminated path from the wheel to a distant this defect is another object of myinvention,` 7o point ahead is essential in order that the. and this Ido by providing prisms whose emer- 2o character of the ground may b e revealed to gent surfaces are not plane, but, on the conenable the rider to avoid obstructions and trary, are slightly convex or curved in crossconsequent danger of injury, though it may section. l g 'be applied to any vehicle-headlight. It is :In the accompanying drawings, Figure 1 75 desirable in order to secure the best results is 'a face' v iew of my improved leus. Figs. 2, z5 that the entire number of light-rays be util- 3, and 4 are sections on the lines 2 2, 3 3, and

ized and concentrated throughout the path 4 4. Fig. 5 represents a series of cross-secto be illuminated, which in the ordinary bitions of the same prism, showing the varial cycle headlight-lens is-not the case. The ob- A tion in the angle at different portions there- 8o jection' to the ordinary lens in use is that it of.. Fig. 6 is a horizontal section of the lens,

3o either illuminates a widearea close to the showing the light-rays by dotted lines. Fig. wheel, while the road .in front is left in dark- 7 is a vertical cross-section, the dotted lines ness, or it illuminates aspot at some distance showing the paths of.,the incident and emerahead, while the road immediately in front of gent rays of light; and Figs. 8 and 9 are ver- 85 the wheel remains dark, in either of which tical sectional views showing, respectively,'a

35 cases the probability of revealingan obstruclens having prisms with curved emergent tion in the road under conditions that will surfaces anda lens having prisms with plane enable the rider to avoid it are greatly diminemergent surfaces, with diagrammatic illusished as comparedv with a lens such as I have trations' of the effect of said constructions 9o devised that will throw a continuous beam upon diverging rays oflight.

4o of light from the Wheel to a remote point in The lens `is preferably, though not necesfront. l sarily, made circular in form, and it may be By my improved lens the rays of light are cast or molded in one piece for convenience concentrated to strike the ground close to the in manufacture. 95 wheel and to extend in a 'laterally-confined In constructing this improved lens advan- 45 path from that point alongthe ground to a tage is taken of the well-known property of considerable distance ahead. These desirable the prism to deflccta ray of light as it passes results are secured by constructing the lens therethrough first toward the normal of theinof prisms whose angles of refraction vary in cident surface and then as it passes from the roo different portions of the same prism-that is, dense medium of the prism into the less dense 5o each prism is so constructed that the angles airaway from the normal ofthe emergent surof refraction at different portions thereof shall face. The direction of any ray of light may be such as to direct the rays of light in an thus be controlled as to its direction of refraction by simply changing the angle of the prism through which it passes. It in the same prisin the angle is uniform-that is, if the angle between the incident and emergent surfaces is the same throughout-the direction of the retract-ed rays will be the same,

`whereas if this angle's made to vary the direction of the retracted rays will likewise vary', and I have taken advantage of this fact to so vary the angle of the -pris'uis -at dierent parts thereof as that tbe rays of light will be directed in a continuons path along the ground, and Ihave so varied the inclination ot the prisms as between themselves that the path shall extend from the wheel continuously to' a great distance ahead.

In the drawings the lens A, shown preferably as circularin shape, has any usual or desired form of center B, either plane or eenvex, and is provided with a series ot contini nous prisms a, a', a?, a3, and a4 ot' any desired number which are preferably shown as annular in foidn, though, as it is quite obvi-l ous, they might be made oval, elliptical, or of anyot-her continuons contou r, and when I use the term annular in the specitication and claims I mean of any continuous contour, as here referred to.

v the emergent surface C at the bottom of the lens is quite small, as represented at f l/, and at the points of the prism between the top and bottom the angle ot the prism, as l will term the angle between the incident and emergent surfaces, varies between :n and y. This variation in angle is well delincd4 in the cross-sections of Fig. l represented by Figs...

2', 3, 4, and 5. In the vertical cross-section 4 ot liig. 2 the angles of the prisms at theitop of the lens are the maximum desired, while those at 'he bottom nl' t-ho lens in the same prism are the minimum in that prism. The cross-section represented by Fig. 3 beinghorizontal, the angle of the several prisms is intermediate ora mean between the angle ol` the same prism at the top and bottom, while Fig.

4, being a section midway between t-hc hori- -j-zontal and Vertical on the line 'i l of liig. l,

shows the angles ot' the prisms at the top and bottom intermediate ora mean between the angles ol` the same prisms in the vertical and horizontal sections.

lt will be clear from the above that nach prism varies'in angle from the top to the bottom of t he tens and that the. angles ol'l adjacent portions ol' thesamc prism ditler-tbatis,tl1c angles ot the prisms in the vertical section ot' l"ig. L dller trom the angles ol' the same prisms Aon through the entire series of prisms.

in the section ofthe adjacent. portion in Fig. 4. The eteet of lthis variation of angle i-n the saine prism is to retract the rays of light differently at different portions of the same prism. For instance, having reference to Fig. 7, let L represent a source of light. Then the rays striking at Z will be retracted by the emergent surface b in the direction of m, which would intersect the ground at a long distance from the lens, t'vbile the refraction of tbe rays striking the incident surface at Z9 will be in the direct-ion of m9,which would intersect the gronn d ata point close to the lens, and the direction of raysrat intermediate points t and l in the same prism will vary according to the anele of the prism* at those points and will be intermediate the directions of m and m9.

It the several prisms were similar or uniform in their inclination, (it, in other words, the prisms a, c', a2, afi, and ai on the cross-scctions of Figs. 2, 3, and i were of the like or similar inclination,) the tendency would be to direct the rays approximately in the same direction as the prism a. just described, with the resulting etfect of illuminating the periphery ot' an oval or ellipse upon the ground, leaving a relatively dark center. To, obviate this, I have varied the angles of the prisms as between themselves-that is, on corresponding portions of adjacent prisms the angle ot' one prism differs from the angle of the other prisms. Referring to Figs. 2, 3, and t, it will be noticed, that the prism a on the cross-sections shown has a larger angle thanprism a', that prism a.' has alargerangle than prism 11.2,' that prisln a2 has a larger angle than prism o3, and so 0n with the entire series ot'A prisms. The result is that while a ray of light entering the prism a at l is by its retraeting-snrface I) directed toward m, a ray ot' light entering the prism a at Z is by its refraetng-surtace b' directed to m, the ray entering at I2 is directed by the surface h2 toward m2, and so 'lhe rayscntering at 3, l, li", l", 7.7, ZH, and l are directed by the surfaces 03,021?, Il, (i7, Il, and b", respectively, toward the points m3, m4, 'l'lt5,nL,-nl7,111.8,and nl." in slightly-divergent paths, so that while the ray of light emerging at surface I is directed to the most distant point and tho ray emerging l'rom surl'aec In is directed to the ground close to the lons at nl. the rays elm-.rging from the intermediate prisms strike the ground one in advance ol' the other, thus forming a continuons path of light from the wheel to themostdistmit point reached bythe retracted ray :it surlliee l.

ly reference t0 Fig. ti il will he seen that the angles ol' dillerent portions o" the same prism on oppositesidesot' the center lot' the lens are the same, so that theI rays ol` light emerging l'rom the surface ot .prism o on either side ol' tho center ol` theylens are directed in nearly parallel paths and l'orm the outer horizontal boundaries ot' the beam of light, while the several prisms varying iu augie as between themselves diret-tibo rays to YOC IIO

light up the entire path between the outer or boundary rnys.

In Fig. I have shown n. single prism and at different portions thereof have illustrated vis represented es of seventeen degrees; at f 3,

- thirty degrees; .tt f2, thirty-seven degrees;

at f' and at f,'the point of greatest angle, forty-four degrees. Of course these angles may be varied within wide limits; but the illustration is explanatory of the general char.- acter of the prisms.

Figs. 8 and 9 are diagrams showing two forms of lens. The former figure shows a. lens having prisms whose emergent surfaces are curved nud the latter prisms whose emergent surfaces are plane, said figures illustrating the loss of light due to interference of the ref rncted rays and its remedy. This "estore of my invention has for its object to prevent the interference of the rays of light, and the loss consequent of such interference is clearly illustrated in these figures. The ra-ys of light proceeding from the source L diverge and upon emerging from the prism shown in Fig. 9 are still divergent.,^owing to the fact that said rays enter the incident surface at an angle and ere refrncted also at an angle corresponding to their angle of divergence.

From an inspection of the diagram Fig. 9 it will be seen that the rays of light refrncted f rom the lower one-third o ofthe upper prism and the upper one-third o of the next adjacent prism intercept each other, and the effeet is to produce in lines at each side ofsaid points of interception areas of darkness.

By making the emergent surface of the prism ofn slightly-curved form transversely, as shown in Fig. S, this fault is corrected and the rnys of light are refrncted in parallel lines, avoiding the darkening.

llnving thus described' my invent-ion, what I claim, :nul lesire to secure by -Letters Pntcnt, is-

l. A lens for vehicle-headlights, having a continuous prism, the angle of Whose emer- 5o gent surface varies throughout the length thereof.

2. A lens for vehicle-headlights provided: with a. series of continuous annular prisms,

the a-ngle of each of which varies throughoutthe prism.

3. A lens for vehicle-headlights providedj A 5. A lens for vehicle-headlights provided with a. series of continuous annular prisms varying in angle as between themselves, and the angle of each of which varies throughout the prism.

6. A lens for vehicle-headlights provided 7o with a. series of continuous annulmprisms varying in angle as between themselves, and the angle of each prism varyingcontinuously from the bottom to the top of the lens.

7. A lens for vehicle-headlights having a' 75 series of continuous annular prisms arranged on one face thereof, the angle of each of which varies throughout the prism, the incident su rface of a-ll the prisms being in the seme plane.

8. A lens for vehicle-headlights having a. 8o

continuous prism, the angle of whose emergent surface varies throughout the length of the prism, said prism havingits emergent surface curved transversely.

9. A lens for vehicle-headlights having a plurality of prisms arranged concentric to each other and to the source of light, and the angle of whose emergent surfaces varies throughout the length of the prisms, said prisms having th ei r emergent surfaces curved 9o trans versely.

JULIAN n. rrrmN.

Witnesses:

A. C. CORNING, Cit/xs. S. PrrKiN.