US1793663A - Headlight - Google Patents

Description

` Feb. 24,1931.

w. H. woon HEA'DLI GHT Filed Dec. il, 1926 william H woad Inventor Patented Feb. 24, 1931 WILLIAM H. WOOD, OE SOUTH E'UGLID, OHIO I HEADLI GHT Application med December-1, 1926. serial No. 151,955.

This invention relates to vehicle headlights and has for its object the provision of a new and improved refiector, usable either alone or in conj unction-with a lens of suitable type for producing a light beam part of which shall be projected a long distance ahead of the vel hicle in the form ofa concentrated ray and otherparts of which shall be castdownwardly and laterally at pointsinearer to the vehicle, and thisv throughout a considerable range of therein, spaced a short distance apart vertically, the purpose being to enable an eleva tion or depression of the refiecti-d beam according to traffic conditions, while maintaining the light pattern substantially uniform. Another obj ect'of the invention is to produce a reflector having 'the above-described characteristics which shall in addition exhibit a l substantial degree'of tolerance as regards ax- 'ial displacement of the filament relatively to the focal region, namely a degree of tolerance which is as great as the accidental variations between lamp bulbs of the same size, make, and type. This application is a continllation of my former application filed July ject-matter` is common thereto.

As set forth in my application filed February 26, 1926, and June 7, 1926, Serial Nos. 90,781 and 114,167 `respectively, I make at least the lateral margins of the reflector substantially paraboloid with its axis approximately horizontal, since thelight pattern produced by this portionof the reflector is least distorted by such a vertical movement of the light'source as is produced bya change from one filament to the other. The rays falling on other parts of the reflector are cast downwardly and laterally by modifying-'the remaining portions of the reflector as herein.- after described.

In the drawings accompanying and forming a part of this application I have shown a preferred physical embodiment-of my inventive idea. Figs. land 2 are respectively 1a yvertical displacement of the light source.

21, 1936 Serial NO- 123,944, so far as the sub-i lution by dotted lines solely to facilitate this the axis a-a and the curve itself is prosle elevation anda front elevation of a rje- Hector embodying my improvements; Fig. 1 being shown partly in section corresponding A to the line 1-1 of Fig. 2; and Figs. 3 and 4` illustrate alternative modes of deriving the curve employed for the central vertical zone illustrated in Fig. 2. l

My improved reflector is characterized essentially by `the relation between its horizontal section X-X and its vertical section Y-'-Y. The former section comprises a pao0 rabola with its axis a-b substantially horizontal; the latter section comprises a para-y bolic curve having a greater downward incli-' nation at every point than that of the para oloid at an equivalent point. 'Ihe portions andB of the reflector surface located adjai cent to the horizontal section arepreferably segments of a surface of revolution .produced by revolving the horizontal parabola 4about its own axis a-b, and the focal point of this portion of the reflector is indicated at fA in Fig. 1. If this surface of revolution were continuous it would produce the complete paraboloid indicated at A B by dotted lines in Figs. 1 and 2. In practice I use for reflect- 75 ing purposes only that portion of such paraby oloid as lies at and near the horizontal central plane at each side of the refiector, but show the remainder of such surface of revodescription.

The vertical axial section corresponding to Y-Y in Fig. 2 conforms vto 4a second parabola having its vertex `located in front ofy the vertex of said 'first paraboloid.` This last curve can be either la simple parabola generated as shown in Fig. 3 or the curve illustrated in Fig. 4.v The curve G illustrated 'in Fig. 3 is a simple parabola wherein every point is equidistant from the focal 90 point4 f and from-*the line D-D perpendicular to the axis a-aand known as the directrix. The curveH in Fig. .4 likewise has a focal point f" but the same is located above duced asfollows. l, vA directrix D-D is drawn perpendicular to the axis a-a.^- A

line m-/m is drawn through `the focal point f and intersecting the axis (LQ-a at the point m', Thereupon a vertical line M-y-M 10o is drawn. through-the focalpoint f andinvis dan@ 'parallel to :lr-'D' as far n the opposite side thereof as m is displaced laterally from thefoeal`.poii1t.V A. point 1n/"isl now found on this line equi'distant from the vline M-M .and the point m and this is 'a point on the curve. Likcwisea linen-,4a

' tersects theline cir/ a at a. A' vertical line ter as -n is displaced inwardly of the focal point and a point n is found on that line i' one side ola G shown in Fig. `3 `bolicjcurve I-I shown N-N is drawn parallel to`D -D and spaced the same distance inside of the latequidistant fromN-N and from nf. Likewise .a line p-p is drawn lthrough the focal.

point intersecting the axis aa-at p and a vertical'line P-P isv drawn parallel to D-D" and as far heh-ind that line as pf is located infront of the focal point thus enabling the location of a point p0 equidistant from P-P and from p. 'The curvethus produced can be considered as essentially/a parabola' having its focal point displaced to of the axis aa and its axis a-a inclined downwardly and forwardly compared with the first named axis. -It

vwill be noted thatA a line S',

S passing through the focal point f.

and from the axis ria. Either the parabor the modified parain Fig. .4 can be employed as a template for the central vertical vtex of the curve which defines the vertical zone C-C. 35

- fined by thevertical section 'Y-'Y shall lean Vfmwaadlyiand downwardly at every point The essential thing is that the curve deas compared with the paraboloid surface defined by the side wings; and it is desirable for practical reasons, though substantially immaterial optically,'that the versection be located in front of 'that of the hori- 'zontal section sinc'ein this way the front of v 15 the reector becomes' more-nearly circular.

A Urdinariily the focal length of the curve de- .ined by the vertical section is less than that' of thev parabola defined by the horizontal section XX as in conjunc- 5o tion with the ydescribed relation of the. vertices to' bring said lfocal -pointssubstantiall-y into the same vertical linebut the-relation of the focal points is much less important than that of the surfaces as defined in this paragraph and is not so good a criterion of my invention as the comparative inclination of the curves both because. of possible variations and because `of the difficulty vof l'ocating the focal point in an existing reflector.

'It must not be supposedv that the axis cfg-c'v constitutes the axis of revolution about which the portion C+C-of the. reflector is produced.' The axis c-'c is merelythe axis of the curve defined by the central vertical section; in other words of thevertical temvthis template about an feature of my A n related D dlrectly tothe directrix IT-D', the points .so-48 being equidistant from such directrix' lwings. These can be regarded asr `surfaces gradually mergin the edgesof-jA bviously such a by' first making a metal'punch according to the description heretofore given and when the same have-1.

plate. Each half ofthe portion Ce-.C is produced byswinging the corresponding half of axis oblique to cc but much further away; for example, the

-upper half of this zone may be considered Vtransverse curvature of the portionI C-C 1 listhan the curvature ofthe parabolid' i' reason the vertex ofthe portion C-C`should adjacent-to its vertex.- It is for this be located forward of the vertexof the paraboloid `A-B invention, as well as lbeing easily proven. In 'referring to these vertices I do not ,imply that either or both of the surfacesmust be actually extended to or throughthe axis but refer more particularly to the imaginary 'extension 'of the surfaces as illustrated in 4Fig-1 in dotted .lines.

, The portion C fallsinside of 'and below the paraboloid Af B at the top of the reiiector. 'At the-bottom center ofthe reliectorth'e two surfaces may merge'exactly as-here Shown,

or either may fall somewhat within or Without the other. This'relation'is not important optically, so long as the two lower outer .margins of this portion fall below the paraboloid AB as indicated at 'gi-1g in Fig. 2. Likewise the twoupper marginsof the portion C must always remain below the par..

raboloid Af C as indicatedat ii-fi' in I1`Iig.'2. This same relation must prevail throughout the four remainingquadrants of thev`l reflector,

`namely that the portionsl E -E above thel center must lie wholly belowand inside, while the p ortion .E-E below thecente'r must Alie wholly below and outside ,ofthe paraboloid surface A B dened'brtlrefside I ransition and with those of C. reflector is bestA produced been followed tothis point it will be found that the remaining sections are comparatively small in area and very nearly matohedfin form so that it is an easy matter to fashion these quadrantsinto connecting surfaces. It" is also permissible to iiat some or all of the'y reflector into vertical striations, if desired.

In case this is done, care must be taken not to, obliterate the essential curvatures and lrelations heretofore described, namely that the vertical section conform to a parabola of `oneof the types mentioned, every point of which shall lean forwardly and downwardly as compared with the paraboloid which \andthis is an important I constitutes the inedian horizontal zone and having its vertex located in frontof the vertex of such paraboloid. derstood that the words upper7 and loivei'f above and below and downwardly eniployed in-this specification relate't-o positions compared with the earths surface when the headlight is in its intended Operative position on a vehicle.

Having thus described iny invention what I claim is:

l. A headlight reflector whose horizontal axial section is parabolic at points adjacent -to and extending inwardly from its lateral niargins', and whose vertical axial section is parabolic at points adjacent to and extend ing inwardly froinits upper and lowerinargins, the focal length of the veitical section being less than that of the horizontal section, and the vertex of the parabola which defines the vertical section being locatedy in front of the vertex of the parabola which defines the. horizontal section.

2. A headlight reflector whose horizontal axial section is parabolic at points adjacent to and extending inwardly froni its lateral inargins, and whose vertical axial section is parabolic at points adjacent to and extending inwardly froni its upper and lower niargins, the vertex of the vertical section being located in front of the vertex of the horizontal section and the axis of the vertical section being below the axis of the horizontal section, in front of the focal point thereof.

' 3. A headlight reflector having portions Aimmediately adjacent its horizontal axis de- ,finedI by segments of a paraboloid, and having a central vertical zone. whose longitudinal section is defined by a parabolic curve hav- `ing a focal point and an inclined axis, the focal distance of such curve being less than that of the first nanied paraboloid and the focal point of such curve being located in 'substantially the saine vertical line with the focal point of said rst paraboloid, the transverse section ofsaid central zone being of less curi vature than said paraboloid.

4. A headlight reflector whose horizontal section is in large part a parabola and whose vertical section both above and below the axis is in large part a paraboliccurve of shorter focal distance than the first named parabola, the focal point of said last nanied curve lying substantially on the saine vertical line with the focal point of said lparabola.

5. A'headlight reflector whose horizontal section is a parabola and whose vertical secl .tioii-isa parabolic curve of shorter focal distance than the first nanied parabola, the focal point of said last named curve lying substantially on the same Vertical line with the focal point of said parabola and the axis of said last curve being downwardly inclined rel'- ative to' the axis of said parabola.

lt should be unlength of the vertical section being less than that of the horizontal section. the vertical central zone having a transverse curvature less than that of the horizontal zone andthe axis of the vertical section being inclined for-1` ivardly and downwardly as compared with that of the horizontalsection, and the vertex of the vertical section lying in front of that of the horizontal section.

T. A headlight ieeetor whose horizontal and vertical axial sections are both in large part substantially parabolic curves, the focal length of the vertical section being less than that of the horizi'intal section. the vertical central zone having a transverse curvature less than that of the horizontal zone, the vertex of the vert-ical section'beinglocated in front of the vertex ofthe horizontal section. and the heel of the reflect-or having a plane portion perpendn'ular tothe refiector axis, which port-ion merges with both the horizontal and vertical zones.

H. A headlightI reflector whose horizontal and vertical axial sections are in large part substantially parabolic curves of unequal size. the fo lal length of the vert' :al section heilig the smaller. the vertical central zone l having a transverse curvature less than that of the horizontal zone. and the lateral inargins of said central vertical zone being located outside of the paraboloid defined by said horizontal zone throughout all the region i the focal length ofthe vertical section being the smaller, tlievertex of said vertical section l being located in front of the vertex of said horizontal section, and said vertical section having a greater forward inclination at every point than is exhibited at equivalent pointsy by the paraboloid defined by said horizontal zone.

l0. A headlight reflector having portions at and for a substantial distance on each side of itsliorizontal axial plane defined by segments of a paraboloid surface, and having theI portions at and near its vertical axial plane leaned forwardly and downwardly as compared with'the first mentioned paraboloid surface at equivalent points, the vertex of all portions at; and iiear\ the axial. plane being located in front of the vertex of said paraboloid. y i

11. A headlight reflector having portions at and near its horizontal axial plane defined by a paraboloid surface whose axis is substantially horizontal and having theportions at and near its vertical axial plane conformlll) - ing in large part toa :parabola which' is:

` everywhere leaned forwardly and downward@ ly as compared with said paraboloid at equivv yalent points, the transverse curvature of said near the-vertical axial 'section defined longi'- tudinallyby alcurve which leans downwardly and forwardly as compared with said parab` oloid 'and defined laterally by a line of last named portions ybeing less than that of the first named portions, and the lateralmargins yof said last named portions lying every-.f '.-wherebelow the paraboloid surface definedv by said firstA named portions."-

112. A headlight-redactor havingiportions" at and near its horizontal axial plane definedby a paraboloid surface whose aiisis substan# tiallyliorizontal, and having portions at fandsmaller .curvature than said paraboloidgpthe .marglns'of said lastI namedportions being yjoined to -theadjacent .margins of'said first named portions by segments which lie wholly4 -l below 'saidparaboloid surface. l f

. '13; 'A headlight relectorhavingy portions at each sidev extending both above and below` the horizontal plane defined by-a paraboloid` i surfacewhoseaiis is substantially'horizon-lg `tal,andy having portions atand near itsvertical axialplane'which exhibit atl every point a downward' leaning as. comparedlwth the extended surface ofsaid first--paraboloidat equivalent points, themarginsfoi` said last fnamed portionsbeing joinedfto-the adjacent margins of said rst named portions by seb- Y ments 'which lie wholly below said paraboloid surface, the portions of said, reflector lying at eachl side of the'centralfvertical'zone themselves having vertical zones of reduced hori- Zontal-'curvature superposed thereon'.

In testimony whereof I` hereunto -aiix my Signature.. v Y v V t .WILLIAM H. woon.'

CERTIFICATE OF CORRECTION.

Patent No. I, 793,663, Granted February 24, 1931, to

WILLIAM H. WOOD.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, lines 58 and 59, claim 5, after the word "is" respectively insert the words in large part; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of April, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents.

Images