US2216156A - Headlight - Google Patents

Description

W. L. BRISTOW HEADLIGHT Filed March 2, 1938 Patented Oct. 1, 1940 PATENT OFFICE HEADLIGHT William L. Bristow, Chicago, Ill., assignor of fiftyone, per cent to Walter H. Latimer, Chicago,

ApplicationMarchZ,1938,SerialN0.,193,396

1 Claim.

This invention relates to improvements in headlights. r

It is anobject of the present invention to eliminatethe glare produced bythe headlights in use .atrthe present time and to effect this elimination of :the glare without in any way detracting from the efliciency of the headlight in illuminating the road.

It:is,furthermore, an object of the present invention to effectively diffuse a portion of the light issuing from the headlight to destroy the glaring effect in the diffused portion, while: another portionof the light issuing from the projector is notinterfered with thereby.

Another object of the invention is to provide a headlight structure within which particularly the marginal rays of the beam of light normally issuing from the reflector are diffused, while the central portion or core of the beam remains unaltered, this 'core of thebeam being thrown axially forward at a levelat which the glaring effect .uponqoncoming pedestrians or drivers of cars would notbesensed.

Another object of the invention is to provide a headlight-in which the anti-glare or difiusing element can readily be assembled without interfering with the structure of other parts of the ordinary headlight.

The invention also has the object of permitting the headlights of known type and those which are already mounted on automobiles, etc., to be equipped with the anti-glare and light diffusing improvement, and to effect this alterat-ionon the ordinary headlight in such manner that the change can be carried out without requiring special tools orwspecial skill on the part of the operator. a

With these and numerous other objects in view, the invention is described in the following specification, in which reference is made to the accompanying drawing:

In the drawing:

Fig. 1 is a verticalsectional view, with parts shown in elevation, of a headlight reflector having the improved attachment;

Fig. 2 shows a front elevation of the headlight with the lens removed;

Fig. 3 shows diagrammatically the shape of the beam of light issuing from the headlight when .closely aspossible in the focus of the paraboloid or'ellipsoid constituting the reflecting surface. In some of the headlights, .a parking light 4 also may be mounted'on the reflector l itself, this parking light usually being of smaller size than \thedriving light 2, and bothof the lamps 2 and 4 being detachably mounted in the sockets 3 and 5 respectively which project through the reflector casing and are held in operative position by suitable bayonet locks 6, l. I

The lamps and reflector are usually protected by means of a casing 8, Fig; 3, and a lens or front glass 9, whichv issecured on the casing in any desired way, and rests against a strip of cork or the like as indicated at).

While theoretically the rays of light emanating from a source located in the focus of a parabolic reflector, should be projected strictly parallel to the axis of the parabola, the headlights of modern construction deviate fromthis strict optical arrangement, for reasons of manufacture or partly intentionally and partly owing to inherent defects, so that a glareis produced which is greatly obnoxious to pedestrians and drivers of vehicles traveling in the opposite direction.

The glare may be primarily due to the fact that the, rays of light are, directly reflected by the highly polished surface I not only parallel to the axis, but also in other directions; and this combination of directly reflected rays of light, while brightly illuminating the road ahead of the car and the space ,up to relatively great height above the traveling surface also produce the glare which disturbs the driver of oncoming vehicles.

In order to avoid the projection of these rays, which have the glaring qualities, the present invention contemplates the insertion of an attach- .ment whichldeflects or diffuses certain of the reflected raysor a great portion of the same, direct-- ing them back again towards the reflecting surface itself, but now in a general direction different from that which a ray of light originating in the focus of the reflector would have. Owing to this deflection of reflected rays, the rays are again projected from the original reflecting surface but they do not issue-from the latter parallel to the axis; they travellat angles to the axis and thereby produce a general diffusion of this light, depriving itlof theglaring effect without, however, decreasing the intensity of, illumination.

The deflecting surface H is located on a ring 12 placedin opposition to the marginal portion of the reflector I. This surface advisably is a surface of slight conicity with the reduced portion of the deflector ring I2 pointing towards the reflector I while the base of the deflector ring I! preferably lies in or close to the plane in which the outer margin of the reflecting surface I also is located. This deflecting conical surface II is, therefore, formed as an annular surface leaving Cir a relatively wide inner opening I3 through which the beams of light reflected from the reflector I in the ordinary way may be projected.

It will be understood from the above that the rays of light emanating from the marginal portions of the reflector I in a direction parallel to the axis of the same will encounter the deflecting surface II and since this deflecting surface itself is constructed as a reflector, the light reflected from the surface I will once more be reflected from the surface II under its angle of incidence. After deflection by the surface II, it again will be reflected by the marginal or some other portions of the reflector surface so as to be projected at different angles to the axis of the reflector. In this manner the core of light projected from the source of light 2 and from the central portion of the reflecting surface I, as indicated at I4, is surrounded by a shell I of greatly diffused light, and it is this surrounding shell of diffused light which causes the glare from the light issuing'from the entire structure to be eliminated.

The aperture of most of the reflectors in use at the present time is a circular aperture, and hence, the outer edge of the deflector ring I2 attached to the reflector I also is circular in order to be properly fitted to the reflector. But many of the lamps in use at the present time have a plurality of filaments which either can be supplied with current individually for driving with dimmed light, or which can be supplied with current collectively to intensify the light, when driving with bright light. It is particularly when the lamps 2 are turned on full brightness to project the beam over a relatively greater distance ahead of the car, that the glaring effect produced by this intensified light is sensed and resented by oncoming pedestrians and drivers of vehicles. The filaments I! in the lamp 2 are frequently arranged in superposition, thereby making the beam of projected light higher than it is wide.

In order to take into consideration this construction of modern incandescent lamps, the

opening I3 of the deflector ring I2 may deviate from a circular opening and may be elongated vertically, as shown, when the filaments are arranged in superposition in a vertical plane. The vertical dimension of this inner opening I3 of the deflector ring I2 will then be greater than 'the horizontal dimension of the same, at the same time thereby creating space through which the light from the parking lamp 4 can be projected through the deflector ring I2.

Owing to the insertion of the deflector ring I2, the area of the core I4 of unaltered light projected directly by the source of light 2 and by the reflector I without diffusion may be reduced, but this reduced core is surrounded by a mantle I5 of diffused non-glaring light.

Fig. 4 illustrates the effect of the light upon a board located at a suitable distance from the front of the headlight. The test showed with a lens 9 as furnished for the test a total spread of light in lateral direction of 96 inches. Of this spread of light in lateral directions, the unaffected core had a width of about 28 inches, While the diffused light is effective over an area, which at both sides of the core I4 has a horizontal dimension of 20 inches. A rim of real dim light may then surround this mantle of diffused light, as indicated at 20. The reduction of the intensity of light, and its diffusion,

in proximity to the bright core is of greatest importance in eliminating the concentrated glare of the headlights.

It will be seen from the above that a diffuser or deflector ring I2 for a portion 'of the light projected by the reflector I greatly improves the conditions without in any way interfering with the safety of the driver on whose automobile this attachment has been installed. It will also be seen that the deflector ring I2 which may be a ring of sheet metal having a highly polished reflecting surface II on that side which is directed towards the reflector I, can easily be installed even on headlights which are already in use. In the embodiment illustrated in Figs. 1 and 2, the outer edge of the ring I2 constituting the deflector or diffuser is held in position by the gasket of cork II] or the like which is frequently interposed between the outer edge of the reflector I and the lens 9 of the headlight, this last named lens being secured in any desired way to the headlight casing. It is obvious, furthermore, that for the purpose of improving the appearance of the device, the deflector ring I2 may be provided with a highly polished surface on both of its sides. The high polish on the outer surface of the ring I2 is of benefit in causing illumination of the space directly in front of the casing through the curved portion of the lens 9.

Again, it may be stated that by applying a reflecting coating only to the surface II of the deflector ring I2, and making the base or ring itself of a metal differing in color from white, the light diffused by the deflecting surface II, projected against the reflector. will also show the shade of the color of the base or foundation of the deflector ring I2, also thereby reducing the glare of the white light usually projected by the ordinary headlight. For the sake of appearance, the deflector ring I2 may be provided with a highly polished reflecting surface on both sides, the one that is directed towards the reflector as well as the one which is directed towards the lens or glass of the headlight, although this is not essential for the present invention. In spite of eliminating the glare from the main portion of the light, the core of bright light issuing from the reflector is in every respect sufficient to illuminate the road to the same extent as with the headlights in use at the present time.

I claim:

In a device of the character described, the combination of a reflector having a curved reflecting surface with a focus, a lamp having filaments in vertical arrangement one above the other, said filaments being in the focal plane of the reflecting surface, a ring placed contiguous to the marginal portion of the reflector and having a deflecting surface of slight conicity with the base of the cone in the plane of the outer margin of the reflector, said ring having an inner opening of greater height than width, through which opening the beams of reflected light issuing from the central portion of the reflector will be projected while the light emanating from the marginal portions of the reflector will encounter the deflecting surface of the ring to be reflected thereby into the reflector and to be projected from the reflector at different angles to the axis of the reflector.

WILLIAM L. BRISTOW.

Images