US1451161A - Headlight ifor automobiles - Google Patents

Description

Apr. 10, 1923;

1,451,161 E. B. HELM HEADLIGHT FOR AUTOMOBILES Filed Dec. 1, 1920 OwMWJ/M my.

Patented Apr. 10, 1923.

UNITED STATES PATENT QFFICE.

EMERSON IB. HELM, OF CLEVELAND, OHIO, ASSIGNOR 0F ONE-THIRD T0 CHARLES L. GEBAUER AND ONE-THIRD T0 JAMES BENNER, BOTH 0F CLEVELAND, OHIO.

HEADLIGHT FOR AUTOMOBILES.

Application filed December 1, 1920. Serial No. 427,519.

To all whom it may concern:

Be it known that I, EMERSON B. HnLM, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Headlights for Automobiles, of which the following is a full,clear, and exact description, reference being had to the accompanying drawings.

This invention relates to automobile headlights and has for its object the provision of a device of this character of very great simplicity which shall utilize all the rays from the light source beneficially and without the production of glaring'or dazzling rays projected at such an. angle as to be contrary to law or obnoxious to travelerspassing in the opposite direction. Other objects of the invention are the provision of a new and improved lamp bulb for automobile headlights which can be used with a plain paraboloid reflector and plain glass closure without waste of light or producing a glare; the provision of a headlight which shall conform to all requirements of law and courtesy merely by the use of a Special bulb and this without any material increase in the cost of such bulb; while further objects and advantages of the invention will become apparent as the description proceeds.

It is the well known property of a paraboloid reflector that all rays arising exactly at its focal point are reflected forward in a strictly parallel beam. However, no known light source is restricted to a geometrical point, and the portions thereof which fall outside of this limit diverge from parallelism, some to a beneficial ex tent and others to an obnoxious extent. It-

is also known in respect of paraboloid reflectors that all rays which arise forward of the focal point are reflected forwardly converging and all rays arising to the rear of the focal point are reflected downwardly diverging; and use has been suggested to be made of this property by displacing the upper half of the reflector forwardly of the lower half so that a single light source located between thefocal points of the respective sections would have its rays cast downwardly by each, in one as a result of convergence and in the other case as a result of divergence. This necessitates the employment of a special reflector which is expensive to make and has certain practical drawbacks. According to my invention the same identical result is achieved with a plain paraboloid reflector by the use of a light source made in two parts longitudinally spaced along the paraboloid axis and located upon opposite sides of the focal point, the source which is forward of the focal point illuminating only the upper half of the reflector whereby its rays are cast downwardly converging, and the source which lies at the rear of the focal point illuminating only the lower half of the reflector so that all the rays are cast downwardly diverging and to produce such a source I employ a peculiar kind of light bulb which I will now describe.

In the drawings accompanying and forming a part of this application I have illustrated certain simple embodiments of my invention. Fig. 1 represents the forward end of an automobile equipped with a headlight of my invention; Fig. 2 is a diagrammatic view of a paraboloid reflector in combination with a source of the type specified; while Figs. 3, t and 5 are sectional views of light bulbs embodying my improvements in practical form.

Describing the parts by reference characters, A represents a plain paraboloid reflector whose axis is indicated at aa and focal point at f. m and a represent the two parts of the source, the portion m being forward of the focal point and giving rise to the rays o(); and the part at being at the rear of the :focal point and giving rise to the rays p-p.

Each source is preferably shielded from the opposite half of the reflector by means of a concave shield R which is preferably made of asmooth and refractory material so as to enable the utilization of the rays which fall thereon; and the sides of these shields are preferably brought sufliciently beyond the axial line on each side as shown at 1-r to enclose the sides of the source, thus preventing lateral rays therefrom from falling on the side portions of the reflector and giving rise to the glare which is most objectionable.

In Fig. 3 these considerations are shown embodied in the most simple form. 1 represents the spherical bulb and 2 the glass post sealed therein and carrying the leading-in wires 3 and 4, the former being attached to the metal shell 5 and the latter to the central insulated contact 6. Carried by this post is the supporting rod 7 to whose outer end is attached thereflector 8 which comprises two hemispherical cups placed side by side along the axis of the lamp and facing in opposite directions. Inside these cups are placed the filaments 9 and. 10 respectively, one end of the filament 9 being connected to the leading-in wire 3 and one end of the filament 10 to the leading-in wire 4 the opposite ends of the filaments being grounded to the reflector 8 which is itself electrically insulated. I have shown the filamentary wires as running generally in an axial direction, since lateral divergence from the axis produces deviations of rays which are particularly hard to correct. The lips of the cups project a sufiicient distance in their respective directions toshut off all lateral rays as shown at 12-12, and the insides of the cups are preferably polished so as to form miniature reflectors. The member 8 is preferably made of highly refractory metal like tungsten or molybdenum inasmuch as its proximityto the incandescent filament causes it to become highly heated.

In the modification shown in Fig. 4 the reflector element 8, instead of comprising two hemispherical cups placed side by side along the axis, consists of two comparatively flat dishes. arranged baclr to back, while the filaments 9 and 10 are arranged one in each as before, and are carried by the leading-in wires 3, 4:, but instead of being grounded to the reflector they are here shown as con nected together in series by a short conduc tor 13. The use of this wire 13 enables the reflector to be made of non-conducting material if desired such as porcelain, glass, or better still, some of the refractory earths;

and this indeed can be used for the reflector 8 shown in Fig. 3, a suitable hole being left for the filament to pass through.

In the embodiment shown in Fig. 5 the reflector 8 is the same as that shown in Fig. 3

and is made of metal, the rod 7 which supports it constituting one of the leading-in wides, while the other leading-in wire 4? is branched and the branches connected one to each of the filaments 9", 10 which are thus arranged electrically in parallel.

These lamps can be made at a cost only slightly greater than the usual plain type of lamp, and when employed in the usual paraboloid reflector fulfill every requirement of a legal, safe and convenient driving lamp. Their range of permissible adjustment is much greater than that of the usual lamp, and all the light emitted is employed usefully. It will be understood that many modifications in the details of manufacture can be made in addition to those herein pointed out which are intended merely as examples of what may be done in connection with my improvements, and I do not limit myself in any wise except as defined in the claims hereto annexed.

Having thus described my inventiomwhat I claim is:

1. In an automobile headlight, in combination, a paraboloid reflector arranged with its axis substantially horizontal, a pair of light sources supported substantially on the axis of said reflector on opposite sides of its focal point, and individual reflectors for said sources, one of said individual reflectors facing upwardly and the other facing down wardly, the source which is forward of the focal point being located in that individual reflector which faces upwardly and the source which is at the rear of said focal point being located in that individual reflector which faces downwardly.

2. In an automobile headlight, in combination, a paraboloid reflector arranged. with its axis substantially horizontal, a pair of light sources supported inside and individual oppositely facing reflectors for said sources, one

of said individual reflectors facing upwardly and the other facing downwardly, the margin of each of said last named reflectors extending sufficiently beyond the corresponding light source to prevent any rays of the same from falling on the horizontal portion of the first named reflector.

In testimony whereof, I hereunto affix my signature.

EMERSON B. HELM.

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