US 2344221 A
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LANTERN' March 14,
2 sheets-sheet 1 Filed March 19, 1942 INVENTOR. Maw Kfm/THE@ AT TOR N EYS.
March 14, 1944. w, TRAUTNER LANTERN Filed March 19, 1942 2 Sheets-Sheet 2 INVENTOR. M/AG/vv 7/'Aur/vsf.
Patented Mar. 14, 1944 LANTERN Wagn Trautner, Hamilton, Ohio, assignor to The K-D- Lamp Co., Cincinnati, Ohio, a corporation of Ohio Application March 19, 1942, Serial No. 435,365
('Cl. 24U-22) 1 Claim.
My invention relates to lanterns particularly designed for use with mobile vehicles or boats in night signaling for purpose of triangulation. The requisites in such a lantern are 360 degrees visibility in the selected plane (usually horizontal), controlled visual angle or width of beam, and maximum utilization of the light source.
In addition the structure must be sturdy, capable of withstanding the roughest kind of treatment, as, for example in. field work mounted on a motor truck, and capable of precise adjustment as Well as ready availability for repairs and replacement of parts.
In one embodiment of the invention this lantern is designed for visibility at 25 miles with an 8 power glass, using as a source of illumination current the discharge of truck storage batteries.
Among other features of the pref-erred embod'- ment is the provision for assembly of the lantern with a maximum of protection against breakage-as by striking limbs of trees in tbe iield at night, without developing blind spots from which the light beam will not be visible.
Basically my invention consists in combining the use of a refracting lens with a reflector or reectors, thereby using practically the maximum available candle power of the light source. In the full circle or 360 degree lantern, the use is that of a cylindrical Fresnel prism, with the light which does not strike the prism reflected by inverse parabolic reflectors with their apices at the axis 'of vthe cylindrical prism, in which axis the light source located.
The drawings and specification that follow illustrate and describe the preferred embodiment, and in the .appended claim, to which reference is hereby made, will be set forth the novelty inherent not only in this embodiment, but in various possible modications thereof which will occur to those skilled in the art in adapting the invention to various purposes and for use in various sizes with various candle power light sources. Y
In the drawings:
Figure 1 is an elevation of the lantern.
Fig. 2 is a section on the line 2 2 of Fig. l.
Fig. 3 is a top plan View with the cover removed.
Fig. 4 is a central vertical section of the device.
The composite Fresnel lens is shown at l. is so designed in accordance with known principles of optics to refract all rays of light striking it from a light source located midway of the vertical of the cylindrical body thereof into a beam either` having no expanding angle or such small expanding angle as may be required. The light source is shown as one incandescent bulb 2, located as last noted.
With such an arrangement an observer look.- ing at the lens when the bulb is illuminated will see a line of light in the vertical dimension of the lens, and if the lens is out so that there is no angle of beam, this line of light will not be visible except from a viewpoint in the plane at right angles to the vertical axis of the lens.
It will be evident that those ligh rays from bulb which pass out through the open ends of the cylindrical lens are not refracted, and furthermore will have to be blocked off if it is required to avoid visibility of the light from above and below. In my lantern I locate two inverse parabolic reilectors 3 and 3c. one above the cylindrical Fresnel lens and one below, with the apices of the reflectors in the axis of the lens. These rerlectors are curved in accordance with known principles of optics to reect the light from the light source in a beam which has no expanding angle or such slight expanding angle as is required. The preferred arrangement results in simplyincreasing the length of the line of light refracted by the lens itself, as Well as adding to the intensity of light overall.
In its fundamentals it remains to note that in my lantern I provide a housing to protect it, which consists of a base 4, and a cylindrical glass housing member 6 which rests on the base, together with a top '5, which covers the glass member. The remaining aspects ofthe invention and of the exemplary structure are not fundamental to my invention as now brieiiy exposed and explained, but will be Variable depending upon the mechanical problems involved in order to t the lantern for specific uses. It may be that a full degrees may not be desired, in which case -i the lantern or lamp will be closed off'.
Referring now to the specific embodiment, the base ll is a circular plate, having a central internally threaded boss l, to receive an anchor bolt for the lantern The base has a rib or shoulder 8 and a. raised peripheral portion 9 between which would result in blocking off the linear beam of light from the lens and the reflectors.
The lower reflector 3a is shaped insofar as light rays will strike it in the form of a cone with a curvature as already noted which will rellect all rays in a line at right angles to the vertical axis thereof, which strike it from the light source. Since the source of light is mounted directly on the reilector, it is practical to position it exactly. To this end a regulation lamp socket I3, is employed, which is mounted on acup shaped element set into the apex of this reflector. The external portion of this element presents a threaded ring portion I4, and a seat l5 surrounding it, as illustrated. Upon this the Fresnel lens is mounted as will be described.
The reflector has a flange 3b developed at its periphery which seats in the channel of the base upon the rubber gasket. The surrounding housing cylinder of glass 6 is seated in the channel on top of the reflector flange. By this device protection against breakage of the glass .and `a cushioned mounting for the light bulb is provided. The base has an entrance tap I5 for introduction of the electric cable for illumination Current to the lamp. By removal of the glass cylinder, the reflector is removable for repairs.
The lens itself, as already referred to is cylindrical and out with the optical effect of projecting a beam of light which has the desired angle of divergence, in this instance very slight, if any. The dimensions of the surrounding glass and housing elements and reflectors with reference to'height of the lens is such that beams of light escaping at top and bottom of the lens will strike the reflectors, thus excluding any escape of rays from the lamp sufciently to make it visible from above.
The lens has developed at its lower portion a rib la, which is seated in the ends of the arms of a spider Il. The central portion lla of the spider is mounted over the ring portion I4 of the lamp mounting cup member, and held in place bymeans of a ring nut I8. Suitable rubber gasket means I9 will be located upon the sea-t l5 from which the ring portion I4 projects.
The electric bulb is located so that its filament will be in the axis of the lens, and in line with the apices of the reflectors and so located with regard to the lens, in this instance midway of its axis, so that the desired refraction of light rays will occur.
The top of the lantern is formed in two pieces, a ring 2i! and the top or cover 5 already referred to. The upper reflector 3 is shaped like the lower one, except that it comes to a point in the axis of the lens. It has a flange 3c, which seats on the ring 20 and is screwed down thereon, with a few screws. This makes the upper reflector easy to remove to replace the lamp if required.
The ring mounts a series of eyelet headed bolts 2! which also may hold the top cover in place. There is a rib 22 developed at the top of the ring 20 and a. rubber gasket element placed on the shoulder outside of this rib. The top plate seats on this rubbergasket, and the eyelet headed bolts project up through the 'top plate, where they are provided with wing nuts. The brace rods are held to the eyelet heads by means of bolts 23, as in the case of the eyelet headed bolts in the base, but here, by turm'ng down the wing nuts on the bolts where they project through the top plate. the glass cylinder will be tightly clamped in place. the ring 20 being provided with a channel 24 on its under side into which the glass cylinder is thrust. Rubber cement is preferably used in this channel to seal the cylinder against this seat. 'I'his seal need not be broken incident to removing the top plate, and unscrewing and removing the upper reflector in order to get at the interior of the lamp.
It may be noted that the interior of the lantern is completely sealed against influx of air or dust to dim the reflectors and possibly result in interference with the angle of reflection or refraction of light rays. Still the interior is readily accessible. Precise location of the Fresnel lens is readily accomplished and if adjustment is re quired shims may be used against the seat for the spider. The whole lantern on the inside is insulated against shocks and jars, and the brace rods provide a continuous protection around the outer glass, against most blows which can be expected from branches of trees, or large pieces of material thrown up by offensive fire.
I have not attempted in this specification to set forth the various uses which occur to me or will occur to those skilled in the art for the lantern of my invention, and it is obvious that the provision of a'housing giving maximum safety and protection will not be required in all instances. So far as I am advised no one has previously provided a lantern which projects a pencil of light of maximum possible intensity from a given light source by the use of refraction and reflection, particularly where this is required through a full 360 degrees of visibility, and with close control of the angle of divergence of the beam itself.
Instead. of a full circle structure, the lantern or lamp could be a half circle, for example, in which instance the lens would surround the light source only in part. Also for small embodiments instead of a Fresnel lens another type of refraction lens could be employed. But whatever Fresnel lens is employed the lengthwise dimensions thereof are necessarily limited by the refractive power to get an emitted band within substantially a non-expanding angle, so that in any case, there will be rays which escape the lens. The reflectors then pick up these rays, and reflect them in extensions of the same band as the lens refracts the rays that impinge upon it.
Instead of using a metallic spider for mounting the Fresnel lens, I have designed a base molded and cut from glass which is cut so as to have no refractive angle, thus adding somewhat to the emission from the light bulb, but this is expensive and quite difficult to make, and I mention it only to the end that it be not excluded as a structure within the scope of my invention.
One of the characteristics of the lantern of my preferred and illustrated form is that the upper reflector and lower reflector while each has the light source at its focus, are not of the same focal length, a circumstance which makes it feasible to mount the light source compactly on the lower reflector and enabling the upper reflector to be conveniently spaced as 'by the glass cylinder or other means. The Fresnel lens may also have a focal length of its own unlike that of the reflectors. l
Having thus described my invention, what I claim as new and desire to secure by Letters Patent ist p A light structure comprising an electric bulb, a Fresnel lens, and upper and lower reflectors of generally conical shape; each of said reilectors having an outer reflective surface generated by the rotation of a parabolic curve around a vertical axis passing through its focus and perpendicular to the axis of the curve, said lower conical reflector being truncated so as to provide an opening, a socket for the bulb mounted in the said opening so as to support the bulb substantially at the focus of said reflective surface, means also mounted on the said lower reflector at the said opening and extending away from the reflector and supporting the Fresnel lens which lens is of less diameter than said reectors and surrounding said bulb, a base on which said lower reflector is mounted, a tubular translucent member of substantially the diameter of said reec- 10 ing said cover to said ring-shaped member.