US 3040172 A
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Description (OCR text may contain errors)
June 19, 1962 CHAN 3,040,172
LIGHTING FIXTURE Filed Nov 12, 1958 2 Sheets-Sheet 1 M W M June 19, 1962 CHAN 3,040,172
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ATTORNEYS United States Patent Ofiice 3,040,172 Patented June 19, 1962 3,040,172 LIGHTING FIXTURE Kingsley Chan, New York, N.Y., assignor to Lightoher, Incorporated, a corporation of New York Filed Nov. 12, 1958, Ser. No. 773,225 1 Claim. (Cl. 24078) The invention relates to the art of spot projection type of lighting fixtures and more particularly to the baffle therefor.
It is among the objects of the invention to provide a bafile for a spot projection type of lighting fixture, that may readily be fabricated at relatively low cost from inexpensive materials, that may readily be mounted into the fixture and which will substantially eliminate reflections due to non-axial components of light from the electric lamp of the fixture, thereby substantially eliminating undesirable brightness within the confines of the bafile which would provide a bright region on the ceiling that contrasted strongly with the surrounding area and hence which would focus the attention of the viewer on the source of the light itself rather than on the object being illuminated.
According to the invention these objects are accomplished by the arrangement and combination of elements hereinafter described and particularly recited in the claim.
In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,
FIG. 1 is a longitudinal sectional view of a lighting fixture incorporating the invention,
FIG. 2 is a top plan view of the baflie unit, and
FIG. 3 is a detail sectional view taken along line 3-3 of FIG. 2.
Referring now to the drawings, the lighting fixture comprises a substantially cylindrical casing 11, the top wall 12 of which has a hollow receptacle 13 rising therefrom. A mounting plate 14 is secured as by screws 15 over the mouth of the receptacle and carries a lamp socket 16 in which a conventional lamp such as a PAR 38 projector lamp 17 is mounted.
The casing 11 is illustratively mounted in a recess in a ceiling 21 so that its lower end 22 is substantially flush with the surface 21 of the ceiling. Although the casing 11 may be mounted in any suitable manner, in the embodiment shown, an annular mounting member 23 is provided comprising a plate having a circular opening 25 and having a cylindrical portion 26 of diameter substantially equal to that of the opening 27 in the ceiling 21 providin access to the recess. The cylindrical portion 26 is formed integral with plate 23 between its inner and outer edges and encompasses the lower portion of the cylindrical casing 11, the portions of the plate 23 inwardly and outwardly of cylindrical portion 26 defining flanges 28, 29.
Seated on flange 28 is an annular gasket 32 positioned beneath the lower end 22 of casing 11, a plurality of screws 33 securing the casing 11 to the cylindrical portion 26.
Positioned in the casing 11 and extending axially thereof from its lower end is a baffle unit 36 which comprises a cylindrical sleeve, preferably of molded heat resistant plastic, such as phenolic which preferably is black.
As is shown in FIG. 2, the baffle unit 36 is desirably formed from two semi-circular sections 36a and 36b, the abutting longitudinal edges 37 of which have complementary projections 38 and recesses 39 to retain the sections together in proper alignment.
Means are provided securely yet releasably to mount the baffle unit 36 in the casing 11. To this end, each of the sections 36a, 36b on its outer surface adjacent its lower end 41 has an inwardly inclined recess 42 defining an annular locking shoulder 43.
Coacting with the shoulder 43 are screws 44, each of which extends through an opening in the end of the inwardly inclined leg 45 of a bracket 46, the inwardly extending horizontal leg 47 of which is secured as by welding to the flange 28 as is shown in FIG. 1.
The inner surface of the bafile unit is molded with a multiplicity of annular ribs 51 each having a flat top surface 52, a relatively sharp inner end 53 and a downwardly inclined bottom surface 54 which extends to the root end 55 of the top surface of the rib therebelow.
In assembling the fixture with the gasket 32 mounted on flange 28 between cylindrical portion 26 and bracket 46, the baffle unit 36 may first be securely mounted on the flange 28 by positioning the lower end 41 of the baffle unit 36 on the flange 28 and then tightening the screws 44.
The cylindrical portion 26 is then positioned over the lower end of the casing 11 and the screws 33 tightened, the resilience of the gasket 32 eliminating the need for close tolerances in the formation of the holes through which screws 33 extend. Thereupon, the unit thus assembled is positioned in the recess in the ceiling and retained in place in conventional manner with the flange 29 resting on the periphery of the opening 27 in the ceiling.
When the lamp 17, which illustratively is of the projection type, is illuminated, a substantially cylindrical beam of light will be projected downwardly to strike the object that it is desired to illuminate.
It is to be noted that the rays of light emanating from the lamp 17, other than the vertical components thereof, would strike the inner surface of the bafile. In the absence of the ribs 51, even if such inner surface was black, if it presented an uninterrupted surface, some reflections would still occur. This would cause an undesirable brightness within the confines of the baflie which would provide a bright region on the ceiling that contrasted strongly with the surrounding area and hence would focus the attention of the viewer on the source of light itself rather than on the object being illuminated.
The ribs 51 serve substantially to eliminate reflections due to non-vertical components of light from the lamp 17 and hence brightness within the confines of the baffle is substantially eliminated.
Thus, referring to FIG. 3, as the rays of light strike the inner surface of the bafile, the rays will take the path illustrated at L so that the visible portion of the inclined bottom surfaces 54 of the ribs will be in a shadow. Thus, reflections due to non-vertical components will substantially be prevented and as the edges 53 of the ribs 51 are relatively sharp, the reflections therefrom will be at a minimum.
Based upon the angle a between a line X extending through the filament 61 of lamp 17 in a plane at right angles to the axis of the bafile unit 36 and a line Y extending from such filament to the lower end 41 of the bafile unit, the angle of cut off of the unit may be determined.
This angle is such that a person would have to be relatively close to a line extending vertically from the filament before he could directly see the lamp 17. Consequently, by keeping the angle of cut oif say greater than 45 degrees, a person in the room at a relatively small distance from a vertical line from the filament 61, even if he looks directly at the ceiling will not be able to see the lamp itself which would be blinding to his eyes.
As many changes could be made in the above equipment, and many apparently widely different embodi- 3 ments of this invention could be made Without departing from the scope of the claim, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:
A lighting fixture comprising a substantially cylindrical casing having a mouth at one end and a wall at the other, an annular flange releasably secured to the mouth of the casing and extending inwardly thereof, a baflle member comprising a sleeve of opaque plastic material having a multiplicity of longitudinally spaced annular ribs on the inner surface thereof and molded integrally therewith, each of said ribs being substantially triangular in cross section having a flat top wall and a bottom Wall inclined downwardly from the inner edge of the top wall to the root end of the top wall of the rib immediately below, the inner edge of each of said ribs being relatively sharp, the periphery of said baflle member at its lower end resting on the inner periphery of said flange, a portion of the outer surface of said sleeve adjacent the end thereof resting on said flange tapering inwardly to define an annular locking shoulder, means carried by said flange reacting against said shoulder releasably to retain the baflie member in said flange, and a socket mounted on said casing wall adapted to support a lamp.
References Cited in the file of this patent UNITED STATES PATENTS 1,839,022 Froget Dec. 29, 1931 1,879,442 ONeil Sept. 27, 1932 1,903,417 Grant Apr. 11, 1933 2,539,927 Ramminger Ian. 30, 1951 2,587,423 Young Feb. 26, 1952 2,795,690 Cooper June 11, 1957 2,796,517 Herzfelder m. June 18, 1957