US3200281A - Two-filament incandescent lamp for non-dazzling high and low beams in automobile headlights - Google Patents

Description

Aug. 10, 1965 TWO-FILAME'NT INGANIiESCENT LAMP FOR NON-DAZZLING R MICKLEY 3,200,281

HIGH AND LOW BEAMS IN AUTOMOBILE HEADLIGHTS Filed Oct. 8. 1962 F IG.I

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INVENTOR. Rolf Mickley ATTORNEYS.

United States Patent 1 tjlaim. oi. sis-air This application for invention relates to a two-filament, incandescent lamp for automobile headlights having nondazzling high and low beams, and is a continuation-inpart of my application Serial No. 220,831 filed August 31, 1962 and my application Serial No. 207,678 filed July 5, 1962.

Application Serial No. 207,678 discloses an incandescent lamp of the type having a paraboloid reflector, a U-shaped highbeam filament positioned horizontally about the focal point of the reflector, and a straight down beam filament extending from behind the focal point axially toward the reflector. The feature of said application is the provision of two shields which together prevent dazzling and are adapted to radiate both a nondazzling high beam which is sharply focused in a horizontal plane and a non-dazzling low beam that is of shorter range and downwardly directed. According to the disclosure a first of said shields extends over the top of the portions of the filaments that extend back of the focal point and under the portion of the filaments that extend in front of the focal point, the focal point not being obscured.

Said application Serial No. 220,831 is a continuation-inpart of application Serial No. 207,678 and discloses an incandescent lamp of substantially identical construction to that of Serial No. 207,678 but specifies that the interiors of the shielding means (facing the filaments) are silvered while the exteriors thereof are frosted.

This invention is based on the discovery that it is also possible with only one anti-dazzle shield to achieve the same illumination effect as hitherto with a system of two anti-dazzle shields. This has the advantage that, on the one hand, even less shielding material needs to be used and arranged inside the incandescent lamp and, on the other hand, the reflection in the upper wall of the glass envelope and the hitherto resulting reflection in the lower half of the reflector, which in part has a dazzling effect, is almost completely eliminated due to the fact that, in accordance with the invention, the U-shaped high-beam filament with its arc-shaped portion is moved back so far into the focal point or to a position where it encloses the focal point so closely that the anti-dazzle shield otherwise located in front of the focal point may be dispensed with and hence the upper anti-dazzle shield located behind the plane passing vertically through the optical axis and intersecting the focal point is alone sulficient to give non-dazzling high and down beams.

The schematic drawing illustrates the mode of operation of this arrangement of parts.

FIG. 1 is a vertical, longitudinal section of a paraboloid reflector in the operation position and indicates the path of the rays resulting from the geometric arrangement of the lamp parts.

FIG. 2 is a view from below the highand down-beam filaments with anti-dazzle shield and the exposed, 11nshielded arc of the U-shaped high-beam filament closely surrounding the focal point.

FIG. 3 is a view from above of the same assembly shown in FIG. 2, likewise with the exposed arc of the U-shaped high-beam filament closely surrounding the focal point and the said anti-dazzle shield.

3,2 ,281 Patented Aug. 10, 1965 The two-filament lamp of the invention comprises a high-beam, U-shaped filament 6, disposed in a horizontal plane about the focal point 2, with the open end of filament 6 toward the parabolic reflector, and a low-or-down beam filament 4 located behind the focal point and between the arms of the high-beam filament. The curved portion of the high-beam filament is moved so far back into the focal point, or is moved back to enclose the focal point so closely, that only an upper anti-dazzle shield 5 located behind the focal point is required for non-dazzling high and down beams. This single anti-dazzle shield extends forwardly to the plane 3 normal to the optical axis 1, intersects the focal point and has its lateral edges extending beyond the sides of the U-shaped filament and down to the horizontal plane defined by the optical axis of the paraboloid reflector. Recesses may be provided in the anti-dazzle shield in this arrangement if a lateral asymmetrical spread of the high and down beams beyond the horizontal plane determined by the optical axis is desired. Glare, especially when no recesses are provided in the anti-dazzle shield, is reduced to exactly the same extent for the high-beam filaments as if the two anti-dazzle shields were installed. The solid angle of the upper half of the reflector which in such case produces dazzling radiation, is eliminated according to the struc ture of the present invention by the positioning of the two filaments with respect to the single shield and the focal point and produces the same effect as is obtained by the two shield device of said application Serial No. 207,678, and in addition the radiation of the high-beam filament produces the optimum effect in accordance with the invention due to the exposed are at the focal point.

I claim:

In a non-dazzling incandescent lamp comprising two incandescent lamp filaments for high and down beams and a paraboloid reflector, the improved anti-dazzling construction comprising as a high beam illuminating means, a coiled filament of Ushaped configuration with the arms of the U extending rearwardly with respect to the opening of said paraboloid reflector,

said coiled filament of U-shaped configuration being positioned in the horizontal plane of the optical axis of said paraboloid reflector with the outer limits of the arm-connecting portion of the U-shaped filament extending only slightly beyond the focal point of said paraboloid reflector,

a 10W beam illuminating means comprising a coiled filament of straight configuration said coiled filament of straight configuration positioned in the horizontal plane of the optical axis of said paraboloid reflector and extending between the arms and to the rear of the central portion of said filament of U-shaped configuration,

and a single anti-dazzle shield extending over that portion of said filaments back of the focal point of said reflector.

References Cited by the Examiner UNITED STATES PATENTS 1,280,626 10/18 Ames 313-111 1,963,672 12/28 Schroeder 313--115 X 1,947,243 2/34 Born 313-115 2,020,130 11/35 Astor 313-111 2,245,793 6/41 Kurlander 313115 2,501,140 4/50 Pique 313-111 GEORGE N. WESTBY, Primary Examiner.

DAVID J. GALVIN, Examiner.

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