US1686593A - Vehicle headlight - Google Patents

Description

Patented Oct. 9,1928.

PATENT OFFICE.

VEHICLE HEADLIGHT.

WII 'JIJLAM H. WQOD, QF SOUTH EUCLID, OHIO.

Application filed May 8, 1926. Serial No. 107,582.

This invention relates to vehicle headlights and has for its object the provision of a new and improved construction of lens which in I combination with reflectors of a certain kind shall produce an improved pattern and distribution of the light, especially when used with what is known as a two filament lamp bulb. Another object of the invention is the provision'of a combination of lens and reflector which shall have such cooperating parts or regions as shalldispense with the necessity for ribbing or corrugating or moulding the glass on more than one side of the lens. l5 The theoretically best form of light pattern has long been known and is characterized by a kind of semicircular or crescent shape with its straighter side lowermost and horizontal, the maximum intensity near the top so as to O afford carrying power, yet with a fairly sharp (but not too sharp) out off. There should be no light above the horizontal except a very little at the center of the beam, but a considerable lateral illumination below the horizontal.

These features alone are not easy to secure but upon these has been superposed the double filament lamp, having two independently usable light sources located, generally, one

above the other and designed to enable the elevation or depression of the beam according to whether the road ahead be deserted or occupied. To afford the best results the shift from one filament to the other should serve merely to depress the beam a few degrees without change of pattern or of color, but the peculiarity of a parabolic reflector is that a shift of the light source from one side of the axis to the other has more than a mere :0 shifting effect; it reverses the pattern, whereas the problem is merely to shift the pattern but without reversal. The problem is complicated by the fact that different parts of thereflector behave ina much different way as regards the light source, and also that anydisplacement of the light source from the focal point tends to produce dark spots in the field. It should also be remembered, although often forgotten, that the direct effect of the lens is comparatively small since more than three quarters of the light emitted by the source falls first on the reflector and only one fourth or less falls directly on the lens. It is possible to make a reflector which alone produces the effect desired, at least substantially, but this is diflicult to accomplish, the bulb must be. located accurately, dark' ,spots are hard to abolish, and the manufacturing and adjusting tolerance is small. The use of a lens which is so designed as to cooperate with the reflector increases this tolerance and smooths out the light beam, and is little if any more expensive than a plain glass cover, which must always be employed in any event to exclude the weather, provided only that it have corrugations on one side only, for the presence of corrugations on both sides increases the expense in a very remarkable way. Accordingly I have produced a combination of lens and reflector which can both be made easily and cheaply and used readily and with wide tolerance in manufacturing and adjusting.

In the drawings accompanying and form ing a part of this application I have shown certain physical embodiments of my invention. Fig. 1 is a vertical, axial sectional view through a headlight containing my improvements; Fig. 2 is a front elevation thereof; Fig. 3 is a view similar to Fig. 1 showing a modification; Fig. 4 is a front elevation of the headlight shown in Fig. 3; Figs. 5 and 6 are sectional views corresponding to the lines 5-5 and 6-6 of Figs. and 4 respectively; and Fig. 7 is a front elevation of another modification. I

The reflector in each case consists of a sheet metal member 1 having a socket 2 for the reception of the lamp bulb 3. At ts two s des the reflector possesses parabohc portions A, A having a common axls a-a, WhlCh 1s substantially horizontal during the ordinary use of the reflector, and with which the socket is generally The portion of the reflector at and near the axial vertical plane, both above and below the axis, is leaned downwardly as compared with the surface of the paraboloid if extended to those points. This produces portions B and C which are shown as below the dotted line A which is in the same surface of revolution with A A. There is considerable lati-g tude of choice as to the exact nature of the surfaces B and C. A very satisfactory construction is to employ a parabolic generator (on the vertical axial plane) with downwardly inclined axes, or they can consist of a number of paraboloids merging together.

centered more or less accurately. I

The'reason for leaning them downwardly is to neutralize the upward glare otherwise pro- I source above or below the focal point. The- I less deflecting power at the regions D which.

portions B and C merge with the portions A A, and the latter may or may not include the heel of the reflector, depending upon their relative width; It makes no difference as regards my invention and only a little 'difference upon the light pattern provided only that thetwo surfaces meet at some polnt behind the plane which includes the focus f of the parabola A A. The portions B, C, whether consisting of one or several parabolas, also have their focal points close to the point 7.

When used with a double filament lamp as shown in Figs. 1 and 3 the filaments 4 and 4 are located one above the other and substantially in this parametral plane. I am not limited to having one filament below and one above the axis since one may be on the axis or both to one side thereof although I prefer to have them on opposite sides but the lower one nearer to the axis.

- It is characteristic of, this reflector that the side wings A A are used for distant lighting and the upper and lower portions for near lighting. In order to cooperate with these requirements the lens 5 which I provide has upright flutes over a considerable part of its surface, designed to spread the light laterally to make it cover the road. These flutes are made with less curvature and consequently lie in front of the reflector portions A A than at the regions E, E nearer the center. This can be efl'ectedeither by making the flutes wider as shown in Figs. 2, 5, and 7, while maintaining the same. depth, or making them shallower as shown in Figs. 4 and 6 while maintaining the same-width. This is for two.

angle of spreading is more effective than in respect of rays which strike the ground more quickly.

These flutes can be strictly vertical if desired as shown in Fig. 7, or can be inclined slightly for the purpose of securing an addi tional dlfl'using effect in a vertical plane without impairing the eflect heretofore described.

This inclination if employed at all should be in opposite directions at the two sides of the central vertical diameter of the lens and a the amount of such inclination should be only small, e. g. from 2 to 10, so that the spread- 1ng effect is always much greater in horizontal plane than vertically.

The ribs of smaller curvature which lie at both si'desof the grooves 9 are shown at 12 and. the rim of the lens hasa flat margin 13. The

flutes or corrugations are preferably on the l inner face of the lens and the shape of this margin is preferably the sameon the inner claim is:

shown as circular in Fig. 7 and exaggeratedly non-circular in Fig 2 and 4:.

I ,do not limit yself to grooves of any, specific form. They may be symmetrical or prismatic. It will be undestood that this range of choice does notoccur with a plain paraboloid reflector butonly with one which is so modified as toemit the distance beam at the two side portions and the near light and curb light at other points.

Inasmuch as the headlight has been designed to operate with two filaments located either above or below the axis it will be understood that it is also valuable for use with a single filament lamp or with a double filament lamp having one filament burned out. It will also be understood that with the wide tolerance in manufacture and adjustment permitted by my improvements it becomes possible to dispense with adjusting devices and make the lamp with fixed focus. It will also be understood that the portions B and C can merge into the portions A A either directly or by way of intermediate, transition, surfaces. The word upright as applied to the position of the ribs includes both the strictly vertical and the limited inclination as illustrated and described. Many changes in detail can, therefore, be made within the scope 'of my invention and I do not limit myself Having thus described my invention what 1-. In a vehicle headlight, the combination 5 of a reflector having at its two lateral portions a pair of opposed paraboloid segments whose axis is substantially horizontal, said reflector having its upper and lower median portions leaned downwardly as compared with the-surface of the paraboloid defined by said lateral portions, a lamp bulb located in such axis and having two independently usable, vertically spaced filaments, and a lens in front of said deflector, said lens having vertical flutes terminating coextensively with the translucent portion of the lens at top and bottom, the curvature of saidflutes being less adjacent the lateral edges of the lens than at re- 2. In a vehicle 'headlight, the combination gions nearer the top and bottom edges thereof a reflector having its two lateral portions consisting of a pair of opposed segments, of the same paraboloid whose axis is substantially horizontal, said reflector having its upper and lower median portions leaned downwardly as compared with the surface of the paraboloid defined by said lateral portions, a lamp socket coaxial with such paraboloid,

and a lens having upright ribs extending from top to bottom of the light-emitting surface and arranged in a bilaterall symmetrical manner upon oppositesides of the central vertical diameter, the transverse curvatureaof said ribs being less in those portions of the lens which lie in front of said paraboloid segments than in those portions of the lens which lie nearer the top and bottom edges thereof, and a lamp bulb in said socket having two independently usable vertically spaced filaments located substantially in the same vertical line which contains the focal point of said paraboloid.

3. In a vehicle headlight, the combination with a lamp bulb having two independently usable concentrated filaments located one above the other,'of a reflectorhaving at its two lateral portions a pair of opposed paraboloid segments whose axis is substantially horizontal and whose focal point is located I onsubstantially the same vertical line which contains said filaments, said reflector having its upper and lower median'portions leaned downwardl as compared with the surface of the para oloid defined by said lateral porae seasea signature.

tions, and a lens having upright ribs formed v at and adjacent to the vertical axis adjacent the top and bottom margins of the translucent portion, said ribs decreasing in curvature to ward the lateral margins of the lens.

4. 111a vehicle headlight, the combination of a reflector having its two lateralportionsat and near the horizontal plane conforming to a single paraboloid whose axis is substanhorizontal, said reflector having its tially medlan portions leaned downwardly at a greater angle than the surface of the paraboloid defined by said lateral portions,- and a iwoon.

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