US981290A - Reflector and search-light. - Google Patents

Description

S. L. LBBBY. REFLECTOR AND SEABQH LIGHT.

APPLICATION FILED OCT. 9. 1909.

Patented Jan. 10, 1911.

Wiliuaaiseo snares STATES LEE LEBBY, F CHARLESTON, SOUTH CAROLINA.

nnrnno'ron AND SEARCH-LIGHT.

Specification of Letters Patent.

Patented Jan. 10, 1911.

Application filed October 9, 1909'. Serial No. 521,943.

To all whom it my concern:

Be it known that I, STATES Lea LEBBY, a-

citizen of the United States, residing at Charleston, in the county of Charleston and State of South Carolina, have invented certain new and useful Improvements in Reflectors and Search-Lights, of which the following is a specification.

My invention relates to reflectors, and has for its object the design and construction of such devices which, while ca able of a wide range of use, are particular y intended for use as search lights upon motor boats and motor vehicles.

The objects of the invention are to provide a reflector which will cast a beam composed of rays which are substantially parallel in a vertical plane and diver ent in the horizontal plane'; and which Wlll cast an intense beam considerably wider than its height.

In carrying my inventioninto effect, I construct the reflecting surface in the form of a modified, or distorted, parabola. As is well known, a circular beam of parallel rays is cast by a parabolic reflector from a light placed in the parabolic focus, and hence the field of illumination is very small. I have discovered that by modifying or distorting the reflecting surface to a desired degree from the true parabolic form, and properly locating the light in relation thereto, a beam of any desired shape may be obtained. For instance, by slightly flattening, so to speak, a true parabolic reflector so that its vertical diameter is diminished and its horizontal diameter is increased, a section taken perpendicular to the axis will be a true ellipse instead of a circle. Moreover, a sect-ion taken on the axis, in any plane, will still give atrue parabola. This modification or distortion will result in deflecting rays of a light, placed in the focus of the original arabola, toward the axis in the vertical p ane, and in spreading them in the horizontal plane. Now, by shortening the focus, or in other words, by placing the l'tght nearer the vertex and in the focus 0 the parabolic section having the shortest focus, therays in the vertical' plane are brought parallel while those in the horizontal lane are caused to diverge a little more. The result is a wide cast, or beam,

- with very little loss in density.

While I have spoken of vertical and horivan in drawin in which zontal planes, it will be understood that these terms are only relative and that the resulting distorted beam may be cast in any plane with respect to the horizontal. V

My invention is illustrated in the accom- Figure 1 is a vertical section taken centrally through my reflector; Fig. 2 is a transverse section taken on line 1- 1 of Fig. 1; and Fig. is a horizontal section taken on line 2--2, of Fig.9.

Referring to the drawings, m, n, represents in vertical section a parabolic reflector having its focus at 0. The dotted circle m n, Fig. 2, showing the cross section of the same. The axis of this parabola is represented b the line pq, Fig. 1.

- For t e purpose of illustration I have shown a reflector designed to give an elliptical cast, the greatest diameter of the ellipse being in the horizontal plane. In this instance, the diameter of the reflector in the vertical plane is diminished, and the diameter in the horizontal plane is increased, so that a section taken through the reflector perpendicular to the axis at any oint forward of the focus will give an e lipse. In other words, the parameter a--c of the parabolic section in the vertical plane is less than, preferably as much less than, the parameter of the parabola m n as the parameter dc is greater than that of parabola m a. The rate of change of the parameter is preferably such as to give rise to a true ellipse a e b d.

The light, 0 which may be an incandescent electric lamp, or any other suitable source of illumination, is preferably placed in the focus of the parabolic section having the shortest focus, thus giving parallel rays in that plane, and all planes parallel thereto. In this instance, it is placed in the focus of the parabola of the vertical section, so that the rays reflected in the vertical planes are parallel, as shown in Fig. l. The light be- 100 My re ector may be produced either in that 110 gent rays, as shown in Figs. 1 and 3. The. exact form of this extension may be varied within Wide limits.

' Many changes may be made in the details of construction and arrangement of parts of the apparatus herein shown and described without departing from my invention, and these I wish 1t understood fall strictly within the scope of the invention. For instance, the light may be located at the mean focal distance of the reflector, or

at any point between the shortest and longest focal point, to vary the form of the cast, The degree of distortion of the reflector also is o tional.

Having descri ed my invention, what I claim as new and desire to secure by Letters Patent of the United States, is

1. A reflectorhaving a reflecting surface in the form of a distorted paraboloid.

2. A reflector having a reflecting surface in the form of an elliptic 'p'araboloid.

3. A reflector having a reflecting surface in the form of a paraboloid slightly flattened forward of the parameters. I

,4. A reflector having a; reflecting surface 1 in the form of an elllptic paraboloid forward of the parameters.

5. A distorted parabolic reflector axial sections of which present parabolas of different parameter.

6. A distorted parabolic reflector an axial section of which in the horizontal plane pre- 7. A reflector having a parabolic section in any plane lying in its axis and an elliptical section in any plane perpendicular to said axis.

8. A reflector comprising a distorted parabolic portion having a difl'erent arameter in diflerent axial planes, and aving an extension the Walls of which are substantially parallel to the reflected rays.

9. A search light comprising a reflector having a reflecting surface in the form of a distorted paraboloid, and a source of light located at the focus of shortest focal distance. v

10. A search light comprising a distorted parabolic reflector axial sections of which present parabolas of, different parameter, and a section perpendicular to the axis presents an ellipse, and -a source of li ht located at the focus of the parabola o short-' est focal distance.

11. A search light comprising a distorted parabolic reflector axial sections of which present parabolas of different parameter, and a-section perpendicular to the axis presents an ellipse, and a source of light axially located back of the focus of the parabola of longest focal .distance.

12. A search light comprising a reflector having a reflectin an elliptic parabo oid forward of the parameters, and asource of light located at the focus of shortest focal distance.

In testimony whereof I have'atfixed my signature, in presence of two witnesses.

STATES LEE LEBBY. Witnesses IVALTER D. SLADE, HARRY KIEFER.

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