US1463643A - Lamp for road vehicles and like purposes - Google Patents

Description

Jufiy 31, 1923.

A. C. WHITEHEAD LAMP FOR ROAD VEHICLES AND LIKE PURPOSES Filed July 18. 1922 Patented duly 3i, i923.

ARCHIBALD CHARLES WHITEHEAD, OF IPSWICH, ENGLAND.

LAMP FOR ROAD VEHICLES AND LIKE PURPOSES.

Application filed July 18, 1922. Serial No. 575,784.

To all whom. it m ay concern Be it known that I, Ancnnmnn CHARLES lVHIrnnnAn, of Ipswich, county of Suffolk, England, a subject of the King of Great Britain and Ireland, have invented certain new and useful Improvements Relating to Lamps for Road Vehicles and like Purposes, of which the following is a specification.

This invention relates to head lamps for road vehicles.-

Hitherto various methods have been suggested for eliminating the dazzling eflect produced by the head-lights of a road vehicle on approaching persons.

The principal'object of the present invention is to provide a novel and improved reflector for such headlights which can be produced by an easy modification of the well known methods of producing reflectors, and which will give in use a beam of light of which part is substantially horizontal, and part is directed downward, it being assumed that the reflector is set in a position corresponding with that of the ordinary reflector.

According to the invention I provide a. head lamp in which, While one part of the reflecting surface (hereinafter called the regular part) is of the well known form, namely, a paraboloidal surface generated by a parabolic segment rotating about its major axis, the remainder (hereinafter called the deformed part) consists of a surface of which the curve is generated by rotating the same parabolic segment about its major axis, the said axis tilting progressively in position during rotation of the gencrating curve, and the tilting taking place about a point displaced longitudinally of the optical axis of the regular part from the focus of such part.

With the above and other objects in view as will be hereinafter apparent, the invention consists in general of certain novel details of construction and combinations of parts hereinafter more fully described, illustrated in the accompanying drawin s, and specifically claimed.

In the accompanying drawings like char: acters of reference indicate like parts in the several views, and:

Fig. 1 is a front view of a reflector constructed in accordance with this invention.

Fig. 2 is a longitudinal vertical section therethrough.

In these drawings, a indicates the regular part of the reflector having a fixed optical axis 6 while 0 is a deformed part or part having an axis that varies between the position of the axis 1) and the axis (1, it being noted that the variable axis tilts about a point 32' positioned rearwardly of the focus p of the regular part. a. The curve 9 shows the position in which the reflector would lie if the same was not deformed, and g is approximately the position of the inner end of an electric filament or source of light.

The manner of forming'the reflector is as follows:

The lower half of the reflector is generated by a parabolic arc revolved from a horizontal position about its major axis through 180. The upper half of the reflector is generated by continuing the revolution of this same parabolic are through the remaining 180, the arc being displaced backward so that the focus is moved to the rear of the focus of the lower half, the cen-' ter of illumination still remaining in rear of the focus of the upper half, and simultaneously with the movement of revolution tilting the axis downward at its front end, the downward tilting being at a minimum, namely Zero, at the beginning of its revolution, lncreasing to a maximum when the arc has been moved through and then decreasing to the minimum during the movement back to horizontal. By means of this operation, the lower half of the reflector will produce a normal reflection, and since the center of illumination is in rear of the focus, the rays reflected from said lower half will be inclined downwardly. In like manner, the downward tilting of the axis of the upper half of the reflector forms this upper half into a species of oblate paraboloid, and by the proper proportioning of the angular displacement of the axis in relation to:

the movement of the parabolic are thereabout, the rays reflected from this upper half and emanating from the light source will at no time be deflected upwards.

It is obvious that mechanically such a construction may be produced by spinning on a form, pressing, or any variety of other we s.

t will be seen from the foregoing, that the downward tilting of the; axis of the deformed part of the reflector directs the light 4 rays from the focus p in a. downward beam, the particular distribution of which is regulated by the extent of displacement between the points 3? and 3) and the angle between the axes b and d. i

A reflector constructed in this manner ensures distribution of light which with proper positioning of the axis 7) in relation to a horizontal line, a distribution of the lightin such manner that the road will be well lit, while at the same time there will be no glare in the eyes of a person approaching the \ehicle. or being approached by it.

There has thus been provided 21 simple and e'flicient device of the kind described and for the purpose specified.

Having thus described the inventioinwhat is claimed is new, is:

A reflector of the class described consisteas es ing of upper and lower halves, the lower half having a reflecting surface of regular purziboloidal form, the upper half having a reflecting surt'ai-e generated by the revolution of a parabolic segment about the major axis of the segment and simultaneously with said revolution tilting said major axis downwardly about a point displaced longitudinally of the axis of the lower half rear- Wardly from its focal point whereby the upper deformed half of the reflector is hodily displaced with reference to the lower regular half.

In testimony whereof I have signed my name to this specification.

ARCHKBALD \CHARLES Wldl'll'lilililll).

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