US 3233088 A
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Description (OCR text may contain errors)
Feb. 1, 1966 c. J. McDoNALD 3,233,088
LIGHTING APPARATUS Filed June 27, 1965 2 Sheets-Sheet l Feb- 1, 1966 c. J. McDoNALD 3,233,088
LIGHTING APPARATUS Filed June 27, 1965 2 Sheets-Shea?l 2 United States Patent() 3,233,088 LIGHTING APPARATUS Clement E. McDonald, River Forest, Ill., assigner to Multi Eicctric Mfg., Inc., a corporation of Iliinois Fiied lune 27, 1963, Ser. No. 291,169 2 Claims. (Cl. Mtl-1.2)
This invention relates in general to lighting apparatus, and m-ore particularly to lighting apparatus which is particularly adapted for installation 4in paved areas; such as road-ways, airport runways, taxi-ways and aprons.
Lighting apparatus which is adapted for us-e in the :abovementioned environment must obviously 'be formed of a sturdy construction to be capable of bearing the load of trucks, aircraft, snowplows and other vehicular traiic which may pass over it. Further, such apparatus should extend a minimum a-mount above the runway surface so `as not to damage the vehicles passing thereover. The general purpose of the present invention is to provide new and improved lighting apparatus of the character described wherein the light distribution is omnidirectional horizontally and of low vertical elevation.
In the prior art it is known to use a light source in a housing having a collecting reflector, either paraboloidal or ellipsoidal in shape, which projects the light upward to a con-oidal reflector, from which in turn it is reflected -to a prismatic ring that diffuses the light in a horizontal plane. Because of the load carrying requirements of the xtures, the .support structure between the openings or windows, through which the light must be projected, are necessarily heavy, and a large portion of the light retiected from the conoidal reflector impinges on the support structure and is lost. An `important feature of the present invention is, therefore, to provide lighting apparatus wherein a minimum amount of reflected light impinges upon the fixture support structure, and a maximum amount of light is reiiected directly lout of the fixture.
In this invention -by the use of a pyramidal configuration of plane reflecting surfaces in number equal to the number of windows, the amount of reflected light which impinges on the necessarily heavy support sections between the windows is minimized; and a maximum proportion of the total light is reflected directly t-o the windows. At the windows, refracting areas of the prism spread the beam laterally to put light in ra-dial areas shaded by the heavy support sections.
A related feature of this invention is to improve the waterproof characteristics of lighting apparatus as described above. This is accomplished by providing the prism with a cylindrical lower section which allows the placement of cementitious material between the outer circumference of the cylindrical section and the housing body making an improved waterproof seal.
An object of the present invention is the provision of lighting apparatus wherein a light beam is emitted from a light source, reected by a suitable reector, and refracted through a suitable prism to pass outwardly through the lighting apparatus in a readily visible condition.
Another object of the present invention is the provision of lighting apparatus as described in the previous paragraph wherein the reliector is pyramidal in conliguration and includes a plurality of planar reilecting surfaces.
A `further object of the invention is the provision of lighting apparatus as described above wherein the prism is provided with a refraction area corresponding to each reection surface.
A still further object of the present invention is the provision of lighting apparatus as described above which is tightly sealed and substantially waterproof.
Still another object of the present invention is to provide lighting apparatus as described above with a light source having a vertically extending filament.
Yet another object of the invention is the provision of a lighting fixture which is simple in construction, eicient in illumination, well adapted for its intended purposes, and relatively inexpensive to manufacture and maintain.
These and other objects of the invention will become more fully apparent from the following specification and drawings wherein:
FIGURE 1 is a front elevational view, partly in section, of a preferred embodiment of the invention;
FIGURE 2 is a plan View of the structure set forth in FIGURE l;
FIGURE 3 is a view taken substantially as shown along line 3-3 of FIGURE 1;
FIGURE 4 is a top plan view of the prism used in the present invention;
FIGURE 5 is a sectional view taken substantially as shown along line 5 5 of FIGURE 4;
FIGURE 6 is a top plan view of the reflector used in the present invention; and
FIGURE 7 is a side elevational view of the reliector shown in FIGURE 6.
While this invention is susceptible to embodiment in many different forms, there is shown in the drawings and will herein be described in detail only one specific embodiment, with the understanding that the present disclosure is to be considered as an exemplication of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.
Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, letter R is used in FIGURE l to designate the runway in which the lighting fixture, designated generally by reference numeral 10, is mounted. The runway R is provided with a plurality of spacedapart openings 11, in which the lighting ixtures 10 are mounted.
Fixture 1t) is provided with a cylindrical housing 12 which is seated within openings 11. An annular ange 13 is provided upon the upper end of housing 12, and is positioned upon a shoulder 14 suitably provided in opening 11. A cover 15, which serves as a barrier to protect the other iixture components, is mounted upon housing 12, and as best seen in FIGURE 1, extends only a slight distance above the top surface of the runway.
Cover 15 includes an annular base 15 with a central bore 16', and having a peripheral portion 17 of reduced thickness that is seated against flange 13 of housing 12. A plurality of recesses 18 are provided on the upper surface of base l1d at circumferentially spaced positions therearound, each recess 18 having a clearance hole 19 adapted to receive therethrough a bolt 29, which passes into an aligned and suitable threaded hole in iiange 13. A gasket 21 is interposed between the bottom surface of portion 17 and the top surface of flange I2 to insure a uid tight connection therebetween.
Cover 15 further includes a crown portion 22 which is integral with ibase 16, and disposed centrally thereof. A plurality of radially extending arms 23 connect crown 22 and base 16, and as best seen in FIGURE 1, arms 23 are inclined from their junction with crown 22 to base 16. It will also be noted from an examination of FIGURE 2 that each arm 23 is tapered in radial extent, which enables a substantially shadow-free beam of light to be emitted, as well hereinafter become more fully apparent. A window 24, through which the light to be hereafter described passes, is provided between adjacent pairs of arm 23.
Disposed within housing 12 and positioned below cover 15, is a light source 2S. Light source 25 is of the sealed beam type, having a vertical lament 26, a convex lens 27, and a parabolic reiector 28. Light source 25 is mounted within housing 12 iby brackets 29 which are secured to the under surface of base 16 by screws 30. Electrical leads 31 extend away from the light source 25 to a suitable source of electrical energy, not shown. A colored filter 33 is positoined above light source 25, and is secured to cover i by clips 34 and screws 35.
An annular prism mounting plate 36 is secured to the bottom of base ltd by a :plurality of screws 37. The inner diameter of plate 36 is smaller than the inner diameter of the bore i6 formed in base 16, so as to define an annular step adjacent the inner diameter of the bore A prism 3. is mounted upon plate 36 within bore i6 and Vis xedly held in rm engagement with the under surface of crown 22. The lower portion 39 of prism 38 is approximately cylindrical in shape, and has a height which is substantially equal to the thickness ofjbase 16. A cementitious material 40 is disposed between prism section 35') and the internal surface of bore 16', to provide a weather-tight seal between prism 38 and base M.
The upper portion 4i of prism 38 is provided with refraction areas 42 having planar light emitting faces 43 which are positioned in alignment with windows 2a. The inner surface of each refraction area 42 is provided with a plurality of substantially vertically disposed corrugationlike projections 44 which etect the proper radial dispersal of the light :beams passing through refraction areas 42. The prism upper portion 41 is disposed at an angle with respect to the axis of the prism lower portion 39, so as to effect the proper angular orientation of the emergent light beam with respect to the ruway surface. The prism portions 45, Which are positioned between refraction areas 42, are aligned with arms 23, and thus do not transmit any light.
A suitable reflector i6 is positioned within prism 38 and is ixedly secured tothe under surface of crown 22, as by screw 47. Pilot means are provided on the under surface of crown 22, in the form of a truncated conical member 48, which is adapted to facilitate the positioning of reflector 46 against the cover. An annular gasket 49 of resilient-material surrounds member 48, and cushions both reilector 46 and prism 38. Reiiector 46 is provided with a plurality of reflector faces 50, each of which is positioned in radial alignment with a prism refractive area 42, and a window 24. lt will be readily understood that refraction areas i2v spread the light beams rellected from reector faces 50 laterally outwardly from windows 24, so that a shadow free beam of light is emitted from the iixture. Reflector 46 is preferably formed of mirrored glass, however, it should be noted that certain highly polished metallic reflectors may also be suitable. The faces Sil on the reflector may be either tlat or slightly concave to provide a more intense beam.
In the illustrated embodiment, re'iec-tor 46 is a truncated, hexagonal pyramid, having a first base Si adapted to ushly engage the under surface of crown 22, and a second base 52 adapted to seat the head of screw 47. While six reflective faces Sil have been provided on reector 46, six refractive areas 42 on prism 38, and six windows 24 in cover 1S, the invention is not limited to a specic number, and more or less than six may be provided if desired. However, it should be noted that the provision of six refractive areas in combination with six reective surfaces has provided a multi-directional light which -is extremely satisfactory, and which fully achieves each of the objects of the invention.
i. Lighting apparatus comprising a housing, a light source mounted in a lower portion of said housing, a parabolic reliector associated with said light source and positioned to reect the light emitted from said source in substantially parallel vertical beams, a cover on said housing, a plurality of radial passages in said cover, a reflector mounted in the housing beneath said cover and positioned in substantial vertical 4alignment with respect to said light source to intercept said vertical beams, said reflector having a number of reiiecting faces equal to the number of radialpassages with said faces being positioned to reilect light impinging thereon generally horizontally outwardly through said passages, a prism surrounding said reflector, said prism having a lower cylindrical portion sealingly engaging the cover and an upper portion having a plurality of spaced light emitting faces inclining inwardly, said light emitting faces being in radial alignment with said radial passages, and means in the housing for intercepting the path of movement of the light for dispersing light prior to its emission from said light emitting faces.
2. Lighting apparatus comprising a housing, a light source mounted in a lower portion of said housing, a parabolic reflector associated with said light source and positioned to reect the light emitted from said source in substantially parallel vertical beams, a cover on said housing, a plurality of radial passages in said cover, a reector mounted in the housing beneath said cover and positioned in substantial vertical alignment with respect to said light source to intercept said vertical beams, said rellector having a number of reiecting faces equal to the number of radial passages with said faces being positioned to reflect light impinging thereon generally horizontally outwardly through said passages, a prism surrounding said reiiector, said prism having a lower cylindrical portion and an upper portion having a plurality of spaced light emitting faces inclining inwardly, said light emitting faces being in radial alignment with said radial passages, and a pluralty of vertically extending juxtapositioned corrugation-like projections on the inner surface of each light emitting face.
References Cited' by the Examiner UNITED, STATES PATENTS NORTON .ANsHER, Primary Examiner.v