US 1249133 A
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Description (OCR text may contain errors)
S. L. LEBBY.
APPLICATION EILED. FEB. 15. I915.
Patented Dec. 4, 1917.
wigjmwm u It? o STATES LEE LEBBY, 0F CHARLESTON, SOUTH CAROLINA.
Specification of Letters Patent. I P w mm 19 41, 1pm,
Application filed February 15, 1915. Serial No. 8,349.
To all whom it may concern:
Be it known that I, STATES LEE LEBBY, a citizen of the United States of America, residing at Charleston, in the county of Charleston and State of South Carolina, have invented certain new and useful Improvements in Projectors, of which the following is a specification, reference being had therein to the accompanying drawing.
My invention relates to the control and production of light, and has for its object the production of improved means for and method of projecting a beam made up of parallel pencils of light in a given directlon with efiiciency and economy.
Heretofore there has been loss in projecting beams of light due to several causes, among which may be mentioned losses by 'disperslon rays passing freely from the source of light without reflection, losses due to improper forming of the source of light, such as the filament, whereby proper focusing is rendered impossible and reflection is straggling, and the improper design of lenses or reflectors, whereby too long a path of travel is given the light rays passing from the source to the reflecting surface.
I attain my objects, first by concentrating the filament into very small dimensions, without seriously impairing its length and efl'ective heat translating resistance; second by blocking ofl dispersion rays; and third by forming my lens or reflector in such Y form and with such a focus that the effective light rays are most efficiently utilized.
My invention is illustrated in the accompanying drawings, in which:
Figure l is a sectional view of a projector with a lamp in place.
Figs. 2, 3 am 4 are detail v1ews showing the arrangement in connection of the filament for six, twelve and 25 volts respectively.
Referring to the drawings,ll is the lens or reflector usually made of glass silvered on the outside, and in the specific form selected for illustration having an extreme diameter of 9 inches and a depth from the plane of the filament to the rear outside silvered surface of 2% inches. The lamp 3 as shown has a substantially spherical bulb fitted with any suitable means for mechanical and electrical connection to the socket 4. The socket is mounted in a sleeve or bushing secured in a central opening in the lens, the mechanical details forming no part of the present invention. The filament 5, as best shown in Figs. 2, 3 and 4 is formed of a helix laid in a small circle and supported upon the insulating post 6 by anchorage wires 7, in a plane transverse to the axis 88 of the lamp, which also coincides with the axis of the lens. In the form illustrated, the diameter of the lamp bulb is about 2- inches, that of the fitting or socket is about 5 of an inch, and that of the filament is about 9,; of an inch. With this diameter of filament, allowing interstitial spaces having approximately the same dimension as the diameter of the filament, there are approximately forty turns in thehelix, each turn having a diameter of approximately of an inch. The total length of this filament is about 8 inches.
In order to cut off or block out the forward dispersion rays from this filament, I
rovide a shield 9, which is preferably formed directly upon the bulb of the lamp, by depositing thereon a thick coating of opaque fireproof compound or paint. Compositions suitable for these purposes are wellspecifically dereflecting surface, indicated by the dotted lines 1010, is greatly decreased as compared with those projectors in which the lens is brought forward to form a greater depth. The efiiciency of my projector depends largely upon this design, while the efliciency of the lamp both separately and in combination with this specific lens is due to the circular helix in a plane transverse to the axis of the lamp and lens.-
In Figs; 2, 3 and 4, I have shown three methods of electrically connecting the filament. In Fig. 2 the helix is connected at four points, opposite points being connected together, and the confluent wires being carried to the opposite poles of the source of supply. This method of connection is used where the lamps are to be fed from a six volt source. In Fig. 3 opposite points on the helix are connected to the opposite poles of the source, the two halves of the helix being thus thrown into parallel, which renders the lamp suitable for use with a twelve volt source. In Fig. 4 the helix is no longer continuous, but is opened at the point 11, and the two ends connected to the two poles of the source, the entire helix being thus in series and suitable for use with a twentyfive volt source.
I am aware that non-essential features in this design may be varied without departing from my invention, and I have not attempted herein to illustrate or describe mechanical details. The essential features of the design are, first the shape and arrangement of the filament in the lamp, and with respect to the lens; second the-shape and dimensions of the lens or reflector; and third the blockin off of the dispersion rays by means of the s ield 9. It is to be particularly noted that on account of the helicocircular shape of the filament the directions of departure of all rays passlng to the lens or reflector are normal to the surface of the filament, that is to say they are at right angles to tangents at the points of departure. So far as I know this has never been attainable with any design heretofore presented, and I have found that my arrangement and combination, as set forth in the appended claims, is exceedingly eflicient as compared with those heretofore in use. It is further to be noted that the brilliancy of projection from this lens is such, and the losses by dispersion are so small, that at a very short distance from the lens, the central spot due to the opaque shield 9 disappears, being entirely covered by centralized refraction and diffusion in the main beam.
Having thus described my invention, what I claim and desire to secure by Letters Patent is:
1. In a projector, a focusing lens-reflector having a very short axis and a relatively great diameter at its widest part, and a lamp comprising a bulb, an anchorage within the bulb, and a filament formed of a fine helix laid in a small circle supported on said anchorage, said lamp being supported within the said lens-reflector with its axis and the axis of its filament anchorage coincident with the axis of said lens-reflector and its rin filament centered on said axis and lyingin 'a plane passing through the focal point of the reflector transversely to the axis thereof.
2. In a projector, a focusing lens-reflector having a very short axis and a relatively great'diameter at its widest part, and a lamp comprising a bulb, an anchorage within the bulb, and a filament formed of a fine helix laid in a circle of very small diameter sup ported on said anchorage, said lamp being supported within the said lens-reflector with its axis and the axis of its filament anchorage. coincident with the axis of said lensreflector and its ring filament centered on said axis and lying in a plane passing through the focal point of the reflector transversely to the axis thereof, together with means rendering the central portion of the end of the bulb opaque, in order to cut off the central longitudinal dispersion rays from the filament. i
3. In a projector, a focusing lens-reflector having a very short axis and a relatively great diameter at its widest part, and a lamp comprising a bulb, an anchorage within the bulb, and a filament formed of a fine helix laid in a circle of very small diameter supported on said anchorage, said lamp being supported within the said lensreflector with its axis and the axis of its filament anchorage coincident with the axis of said lensreflector and its ring filament centered on said axis and lying in a plane passing through the focal point of the reflector transversely to the axis thereof, together with a shield covering the central portion of the end of the lamp bulb, said shield having a diameter determined by the shape and diameter of the lens-reflector, and only sufiicient to cut off the central longitudinal dispersion rays outside of the edge or boundary of said reflector.
In testimony whereof I aflix my signature in presence of two witnesses.
STATES LEE LEBBY.
H. H. Lowrns'ram, JAMES H. MARE.