US1998475A - Automobile headlamp - Google Patents

Description

.A ril 23, 1935.

D. DQWAUGH AUTOMOBILE HEADLAMP Filed 00's.v 24, 1933 Patented Apr. 23, 1935 UNITED STATES PATENT OFFICE 2 Claims.

The invention relates to improvements in automobile headlamps, and the objects of the improvements are: first, to provide a properly focused horizontally spread beam of light; second,

to absorb all the light emanating from the filament and not passing directly from it to the reflector, thru the lens, to take part in the horizontally spread beam of light; and third, by eliminating all the light not focused in the horizontally spread beam of light to create a glareless headlamp,

One form of the invention is illustrated in the accompanying diagram, Figure 1 is a horizontal cross-sectional view of the headlamp. Figure 2 is a longitudinal vertical sectional view. Figure 3 is a transverse section of the headlamp, and Figure 4 is a detail view of the bulb and its support, taken on line I--4 in Figure 3.

The electric lamp is composed of a spherical bulb, 6, with a centrally placed filament, ID, and a dull black semispherical diaphragm, II, placed between filament, ID, and base, I2, in such a way as to absorb that part of the light from filament, I0, directed in its direction. Within this system the part of the light directed away' from the diaphragm, II, will partially pass thru the spherical bulb, 6, without refraction. However some of it, I, will be reflected from the surfaces of the spherical bulb, 6, and will be absorbed on the diaphragm, II.

The lamp is mounted in a conventional base, I2, suspended by one or more arms, I3, from the side of the lamp, the surfaces of the arms, I3, being dull black. 7

There is a dull black area, 4, at the apex of the reflector, 3, absorbing the light, 5, which would otherwise be reflected back onto the spherical bulb, 6, giving rise to light other than directly from the filament, II], to the reflector, 3.

A dull black ring, 9, separating the reflector, 3, from the lens, I, at their peripheries, completes an optical system which absorbs all the direct light from the filament, I0, not striking the reflector, 3, as well as absorbing the light, 5, which would otherwise strike the bulb, 6, after reflection.

The only unabsorbed light, 8, from the filament, I 0, is therefore that striking the reflector, 3.

The reflector, 3, is parabolic on vertical cross section whereby the rays at this section are substantially parallel; and hyperbolic on horizontal cross-section whereby the rays at this section are divergent from the vertical focus, I4, situated at any distance behind the reflector, 3, to give the required divergence to the beam.

A cover glass, I, whose vertical cross section is a straight line and whose horizontal section is an arc of a circle having its center at the vertical focus, I4. All the light passing thru it does so substantially perpendicularly, thus not being refracted, and that light being reflected fromvits surfaces, passes backwards in the same path to the reflector, 3, thru the filament, III, and is absorbed on the diaphragm, II,

Such an optical system as this, absorbs all the light that is not directly reflected from the filament to the horizontally spread beam of light. With this beam properly directed below the oncoming motorists eye level there is substantially no light striking his eyes and therefore there is no glare.

I claim:

1. In an automobile headlight, the combination of a reflector whose vertical-cross-section is a parabola and whose horizontal section is a hyperbola having the same optical axis as the parobolic section, a source of light placed in the focus of the parobolic cross-section, said source of light comprising a bulb mounted with its base directed forwardly from the reflector, a screen placed forwardly from the source of light in position to intercept all light passing forwardly from the source which would not be intercepted by the reflector, a non-reflecting area at the apex of the reflector, a cover glass at the front' of the reflector whose vertical cross-section is a straight line and whose horizontal section is an arc of a circle having its center at the vertical focus of the hyperbolic section whereby all'rays passing out of the reflector are substantially per pendicular to the cover glass.

2. In an automobile headlight, the combination of a reflector whose vertical cross-section is a parabola and whose horizontal section is'a hyperbola having the same optical axis as the parabolic section, a source of light placed in the focus of the parabolic cross-section, said source of light comprising a bulb mounted with its base directedforwardly from the reflector, a screen placed forwardly of the source of light in position to intercept all light passing forwardly from the source which would not be intercepted by the reflector, a non-reflecting area at the apex of the reflector, a cover glass at the front of the reflector whose vertical cross section is a straight line and whose horizontal section is an arc of a circle having its center at the vertical focus of the hyperbolic section, a light absorbing ring extending between the periphery of the reflector and that of the cover glass, whereby all rays passing out of the reflector are substantially perpendicular to the cover glass.

DAVID DARWIN WAUGH CERTIFICATE OF CORRECTION.

Patent No. 1,998,475. April 23. 1935.

DAVID DARWIN WAUGH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: First column, line 53, second column, line i, and lines 31 and 50, of claims I and 2, for "vertical" read virtual; 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 9th day of July, A. D. 1935.

Bryan M. Battey (Seal) Acting Commissioner of Patents.

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