US1564471A - Electric light - Google Patents

Description

. Dec. 8,1925. 1,564,471

c. w. DAKE ELECTRIC LIGHT Original Filed Feb 23. 1923 Jitorngyg Patented Dec. 8, 1925.

UNITED STATES FATEN'E' @FFEQE.

CHARLES W. DARE, OF CHICAGO, ILLINOIS.

ELECTRIC LIGHT.

Original application filed February 23. 1923, Serial No. 620,581. Divided and this application filed.

February 29, 1924.

To all whom it may concern:

Be it known that 1, CHARLES TV. DAKE, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Electric Lights, of which the fOllOWiIig' is a specification.

My invention relates to an improvement in electric lights for use especially in connection with locomotive electric headlights and similar purposes Where an incandescent electric light is used as the source for an illuminating or search light'ray associated with a parabolic reflector. This application is a division of my copending application Serial No. 620,561, filed February 23, 1923.

It is, of course, a known fact that the best place for such a source of light is at the focal center of the reflector, and that the farther away the source gets from the focal center the less satisfactory becomes the light.

It is impossible to have all of the light at the focal center, and I have discovered that the next best place is to have the light filament strung along the central axis of the reflector, passing through the focal point. Next to this tlfe best place for the light is in a plane perpendicular to this axis and passing through the focal point.

Especially in connection with locomotive electric headlights where the voltage is comparatively low, it is necessary, in order to get a lamp which will comply with the necessary service conditions, to have a filament which is of comparatively great length, and in the past it has been the practice to provide the filament arranged in a grid in a plane perpendicular to the focal axis.

I propose to provide in my bulb for incandescent light a comparatively large portion of the filament located on or immediately adjacent to and surrounding this focal axis and projecting both in front of and behind the focal point. I propose to locate the balance of the filament in the plane perpendicular to this axis and passing through the focal point. Experience shows that this arrangement results in a maximum of illumination and prevents the presence of any dark spots or dark areas in the beam of light.

My invention is illustrated more or less diagrammatically in the accompanying drawings wherein- Serial No, 895,893.

Figure 1 is a section through the reflector showing a side elevation of the light bulb in place therein;

Figure 2 is a perspective view of the bulb itself; and

Figure 3 is a top plan view thereof.

Like parts are illustrated by like characters throughout the specification and drawings.

A is the glass bulb or globe of the conventional type of incandescent electric light. It is provided with a screw-threaded base A adapted to be screw-threaded into a socket and cemented as at A Projecting upwardly from the base is a support A of glass or other suitable material, in which are imbedded or inclosed conductors A and A This support terminates at its upper end in a base A from which project upwardly the three supporting arms A, A A and a holding hook A Passing through the wall of the base A and associated with the conductor A is a conductor hook B, which is curved away from thefilament and terminates on the focal line, where it supports the outward end of a coiled filament B This coiled filament extends inwardly along the focal line, passing through the focal point, and is held by the hook A at a point behind the focal plane. An inclined stretch or branch of this filament extends from the hook A to the support A", which terminates in the focal plane. From here the filament extends to the hooks A A back to a point adjacent the hook A where it is carried by the conductor and support B which passes in through the wall of the member A and terminates at the conductor A thus giving an arrangement by which the coiled filament is supported in comparatively short coiled sections insulated except at the two ends where it is mounted on the conductors, and anchored and positioned partially in the focal line.

The filament itself is preferably formed of a single closely coiled spiral wire of the usual type. This coil is so fine and so close that for all practical purposes it may be treated and considered as a single straight wire, and while geometrically, of course, the size of the coiled wire portion is large in fact, nevertheless, being placed right on the focal line as it is, it may for all practical purposes be considered as an incandescent filament on the focal line. The same comment applies to that part of the filament located in a plane perpendicular to the focal line.

C is a parabolic reflector supported in any suitable manner. In the form herein shown the lamp base A penetrates the center of the reflector. lVhile this is the preferred form of my invention, 1 do not wish to limit myself'to this use. I might mount the bulb with its base passing through the side wall of the reflector, the position of the filaments in relation to the base being suitably changed to maintain the relation of filaments to the focal point or focal axis above described.

I claim:

1. The combination with a reflector havilig a focal axis and a focal point, of a single, ccntinuous luminous filament extending in part along the focal axis both in front of and behind the focal point and located in part in a plane perpendicular to the axis and intersecting it at the focal point.

2. The combination with a reflector having a focal axis and a focal point, of a light bulb having a luminous filament comprising in part a longitudinal section lying along the focal axis of the reflector and a plurality of transverse sections at an angle to each other, located in a plane perpendicular to said axis at the focal point.

3. The combination with a reflector having a focal axis and a focal point, of a light bulb having a luminous filament comprising in part a longitudinal section lying along the focal axis of the reflector and a plurality of transverse sections at an angle to each other, located in a plane perpendicular to said axis at the focal point, the filament itself comprising a closely coiled wire spiral.

Signed at Chicago county of Cook and State of Illinois, this 26th day of February CHARLES W. DAK

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