US1721611A - Head lamp - Google Patents

Description

y 1929. F. P. WEBSTER 1,721,6ll

HEAD LAMP Filed Jan. 10, 1927 "3 Sheets-Sheet l [In ch10: Dar/K 1 7M155 fa July 23, 1929. F. P. WEBSTER 1,721,511

HEAD LAMP Filed Jan. 10, 192'? {Sheets-Sheet 2 July 23, 1929. P, WEBSTER 11,7215

. HEAD LAMP Filed Jan. 10, 1927 S'Sheets-Sheet 6 fm/enfor.

Patented July 23, 1929.

UNITED STATES PATENT OFFICE.

FRANK P. WEBSTER, 0F TORONTO, ONTARIO, CANADA, ASSIGNOR OF ONE-THIRD TO HARVEY OBEE, OF TORONTO, CANADA.

HEAD LAMP.

Application filed January 10, 1927.

The principal objects of this invention are to provide a head lamp which will project the rays of light in such a manner as to effect the maximum of efficiency in road lighting while obviating the undesirable and dangerous effect of upwardly reflected or vagrant rays which cause headlight glare.

The principal features of the invention consist in the novel construction and arrangement of the reflector and a lens having its principal axis arranged below the source of light, whereby the central rays are concentrated in a central beam projected horizontally and downward and the remaining rays are c ispersed downwardly and laterally at a wide angle producing intense road illumination without upward glare.

In the accompanying drawings, Figure 1 is a vertical mid-sectional view of a lamp constructed in accord with this invention.

Figure 2- is a vertical mid-sectional view, on a smaller scale than that of Figure 1, illustrating principally the relation of the half spherical reflector with the source of light and their relation to the top and bottom reflectors and the lens.

Figure 3 is a vertical mid-sectional view similar to Figure 2 illustrating the direction of rays from the source of light reflected from the top and bottom reflectors.

Figure t is a horizontal mid-section of the lamp taken through the source of light and showing the lateral reflection of the rays from the upper reflector on the upper side and from the lower reflector on the lower side.

Figure 5 is a perspective detail of the inte-- rior of the lamp with the upper reflector removed, the outer enclosing casing being in horizontal section.

Figure 6 is a diagram showing a vertical section of a lens with a vertical cylinder area on the spherical face and illustrating the ray projection.

Figure 7 is a horizontal diagram of the lens shown in Figure 6 illustrating the ray projection.

Figure 8 is a small scale diagram showing the dispersion of rays in the central vertical plane.

Figure 9 is a small scale front elevational view of the lamp. Fig. 10 is a vertical mid section showing a modified structure of reflector.

Headlight glare is one of the most dangerous elements of present day transportation Serial No. 160,190.

conditions and many devices have been conceived in endeavours to minimize or obviate the difiiculty. The present device has been evolved on practical optical lines and is based on the use preferably of a plano-convex or bi-conveX lens with the source of light placed above the optical centre or principal axis of the lens.

In carrying this invention into effect the source of light A which is the usual electric lamp is placed back of the lens B at such a distance and in such a position above the optical axis of the lens B that rays from the lowermost portion of the filament C of the lamp A will be projected horizontally or slightly downward from the horizontal.

All other rays of light in the vertical plane passing through the lens will be directed downward at an increasing angle from the horizontal. It is preferred to oflset the downward direction of the rays, of the lower portion of the lens by grinding the back thereof in a prism E.

Back of the lamp A is arranged a spherical reflect-or F the transverse axis of which cuts the centre of the filament C so that all rays emanating from the filament and striking the reflector will be reflected back through the filament.

A vertical shield G is placed to cover the front of the reflector F, said shield having an opening 9 centrally arranged to accommodate the lamp bulb. This shield prevents rays of jiglit from an outside source being reflected )ac t.

It will of course be understood that all rays of light reflected by the reflector F so as to strike the lens B will be directed fan-shaped from the horizontal downward and fanshaped laterally but on account of the decentering of the lamp in relation to the lens no rays will be projected above the horizontal.

Extending forwardly from the shield G above a horizontal line drawn from the lowermost point of the lamp filament C is arranged a spherical reflector H which is so placed that rays of light striking the surface adjacent to the shield G will be reflected horizontally while rays of light from the uppermost part of the lamp filament which pass the perimeter of the lens B at the top will be reflected downwardly at a sharp angle as illustrated in Figure 3. All intermediate rays will be directed outwardly at varying angles between a sharp decline and the horizontal in a vertical plane while they will be dispersed laterally to both sides at angles ranging from parallel with the central axis to a sharp outward angle, as illustrated by the upper half section of Figure l.

Extending forwardly from the lower half of the lamp A is a reflector I which has a spherical formation 00 at its inner end extending to the opening 9 in the shield and the outer portion y is of conical formation. The surfaces of this reflector are such that all rays in a vertical plane striking its surface are deflected below the lens as shown in Figure 3, while others in planes extending to the horizontal are deflected laterally as illustrated in the lower half of Figure 4E.

The upper and lower reflectors H and. I are secured to a horizontal plate J which is also connected to the vertical shield G and this plate extends inwardly and supports a su] stantially conical shaped shield K which car ries the lens B. The walls of the shield K are directed to the outer limits of the lamp filament so that all rays reflected from the spherical reflector F or which extend directly forward from the filament and strike the lens will be within its confines while rays which will pass the perimeter of the lens will not be intercepted thereby.

It will be understood from this description that practically all the light rays emanating from the lamp are utilized, those projected into the spherical reflector F being returned and all rays are completely controlled and di rected to project a strong central beam which does not project above the horizontal and to spread light laterally both sides of said beam.

It may be desirable to diverge in lateral directions more of the rays passing through the lens than is accomplished by the use of a spherical lens and in Figures 6 and 7 I have illustrated the diverging effect of a combined sphere and cylinder. The upper edge of the cylinder surface I) is preferably arranged in horizontal alignment with the filament of the lamp and it has the effect of diverging the rays in or near the vertical plane in a direction nearer the horizontal as shown in Figure 6, while the lateral rays are diverged outwardly a sharper angle as shown in Figure 7.

Other lens formations may of course be adopted to apply the science of optics to the direction of the rays so long as the rays are prevented from straying in upward directions. The surfaces of the shields G and K and the plate J are preferably finished dead black so that outside rays striking these surfaces will not be directed on to the reflectors to cause glare.

The lamp A is shown provided with an adjusting screw L which may be of any suitable form and arrangement so that the filament may be adjusted to its proper position inrelation to the lens and the reflectors.

The structure described may be enclosed within a suitable casing hf, though the shape or design has no part in the function of the light.

It may be found desirable to alter the shape of the reflector H to centralize more of the rays in a central beam and a modification of shaped is illustrated in Figure 10. The form here shown consists of two part spherical reflectors h and It so arranged as to direct the rays striking the innermost portion of each reflector in a horizontal direction while the rays striking farther out are directed downward at a lesser angle from the horizontal than the rays reflected from the single sphere reflector H shown in Figure 3. This arrangement will result in more rays of light being reflected at a greater distance from the lamp.

A head lamp constructed as described will be very efficient and will obviate entirely the glare conditions causes by vagrant or unconrolled rays and not only is glare eliminated from its own source of light but the construction renders impossible the reflection back of light from any source in front of or approaching same.

What I claim as my invention is 1. In a head lamp, the combination with a source of light, and a lens decentred in relation to the principal axis of the source of light and directing the rays of light passing therethrough horizontally and downward from the horizontal, of an upper half reflector having a spherical contour adapted to direct rays from the source of light progressively from the horizontal downwardly, and a lower half reflector separate from the upper half and having a part spherical and part conical contour directing rays from the light source progressively from the horizontal downward.

2. In a head lamp, the combination with a source of light, and a lens decentred in relation to the principal axis of the source of light and directing the rays of light passing therethrough horizontally and downward from the horizontal, of an upper half reflector having a spherical contour adapted to direct rays from the source of light progressively from the horizontal downwardly, and arranged wholly forward of the light source, a lower half reflector separate from the upper half and having a rear spherical port-ion and a forward conical portion to effect the directing of the rays from the light source progressively from the horizontal downward, said latter reflector being arranged wholly forward of the light source, and a hemispherical reflector arranged concentric with and rear- Wardly of the light source.

3. In a head lamp, a source of light, a lens having its principal axis arranged below the source of light and presenting back plane surfaces and having its spherical surface deformed'in part to effect an increased horizontal distribution of the light rays passing therethrough directing the rays of light passing therethrough horizontally and downward from the horizontal, reflectors arranged above and below said lens adapted to direct 'all light rays not intercepted by the lens in paths ranging from the horizontal downward, and a half spherical reflector arranged back of said light source and centered therewith.

4. In a head lamp, a source of light, a lens arranged in front of said source and having its axis arran ed below the light source and directing all light rays passing therethrough in paths not rising above the horizontal, a part spherical reflector arranged above the horizontal axis of the lens to direct all rays of light reflected therefrom in paths ranging from horizontal downward, a reflector arranged below the light source directing all rays of light reflected therefrom horizontal and downward, a horizontal non-reflecting plate supporting said reflectors and said lens, and a conical shield supporting said lens and extending rearwardly toward the source of light and having an open inner end.

5. In a head lamp, a source of light, a lens presentin a forward surface spherical in part and having its principal axis arranged below the source of light and imparting a horizontally forward and downward deflection of the light rays passing therethrough, the remaining portion of said forward surface of the lens presenting a cylindrical surface to impart a lateral horizontal divergence of the light rays passing therethrough, reflectors arranged above and below said lens of dissimilar contours adapted to direct all light rays not intercepted by said lens in paths ranging from the horizontal downward, a half spherical reflector arranged back of said light source, and means for adjusting said light source in relation to said half spherical reflector and the lens.

6. In a head lamp, a light filament, a reflector having a half spherical portion arranged back of said light and directing all reflected rays back through the filament forming an inverted image thereof, a reflector of spherical contour arranged above said light forwardly of the rear reflector, a reflector spherical in part and extending into conical form arranged below said light forwardly of the rear reflector, a non-reflecting shield arranged between said upper and lower reflectors, and a non-reflecting shield arranged vertically between the rear and forward reflectors.

FRANK P. VEBSTER.

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