US3131874A

US3131874A - Luminaire

Info

Publication number: US3131874A
Application number: US175965A
Authority: US
Inventors: Kenneth E Fairbanks
Original assignee: Corning Glass Works
Current assignee: Corning Glass Works
Priority date: 1962-02-27
Filing date: 1962-02-27
Publication date: 1964-05-05
Anticipated expiration: 1981-05-05

Description

May 5, 1964 K. E. FAIRBAN KS 5 Sheets-Sheet l s cu INVENTO Y ZM @gal rro/e/VEY May 5, 1964 K. E. FAIRBANKS 3,131,874

' LUMINAIRE Filed Feb. 27, 1962 5 Sheets-Sheet 2 May 5, 1964 K. E. FAIRBANKS LUMINAIRE 5 Shee'cs-Sheei'l 3 Filed Feb. 27, 1962 LUI a /N VEN To R /fE/v/vfh' Firman/wfg United States Patent O Glass Works, Corning, N.Y., a corporation of New York Filed Feb. 27, 1962, Ser. No. 175,965 6 Claims. (Cl. 240-106) This invention relates to luminaires and more particularly to luminaires and refractors for use therein which are capable of directing substantially all light emitted therefrom throughout 180 in horizontal directions about the luminaire and with its greatest intensity in directions horizontally separated by approximately 148 and at angles of about 72 above nadir.

Such light distribution is especially desirable in luminaires intended to be mounted on a wall and to distribute light throughout an area in front of the luminaire and along the ground adjacent to the wall in both directions from the luminaire, and it is an object of the invention to provide such a luminaire.

This object is accomplished by the provision of a luminaire having a concavo-convex refractor in the general form of a frustum of a triangular pyramid but having slightly curved faces, one face of the frustum having on its exterior surface a series of internally reflecting surface prisms and the other faces having on each surface thereof series of parallel generally triangular refracting surface pr1sms.

The construction of the luminaire is illustrated in the accompanying drawing, in which:

FIGURE 1 is a plan View of the interior surface of the refractor,

FIGURE 2 is a side elevational view of the refractor,

FIGURE 3 is a sectional view taken on line 3 3 of FIGURE l,

p FIGURE 4 is a fragmentary plan view of the exterior surface of the bottom of the refractor,

FIGURE 5 is a sectional view taken on line 5 5 of FIGURE 1,

FIGURE 6 is a sectional View taken on line 6 6 of FIGURE 1,

FIGURE 7 is a sectional View taken on line 7 7 of FIGURE 4,

FIGURE 8 is a sectional view taken on line 8 8 of FIGURE 1,

FIGURE 9 is a sectional View taken on line 9 9 of FIGURE 8,

FIGURE 10 is a sectional view taken on line 10-10 of FIGURE 1,

FIGURE l1 is a sectional view taken on line'11 11 of FIGURE 10,

FIGURE 12 is of FIGURE l,

FIGURE 13 is a sectional view taken on line 12-12 a sectional view taken on line 13 13 FIGURE 18 is a polar diagram showing the lateral distribution of light from the luminaire,

FIGURE 19 is a polar diagram showing the vertical distribution of light from the luminaire, and

FIGURE 20 is a longitudinal sectional view of a luminaire according to the invention.

The refractor 26 of the present invention is symmetric about a plane through its longitudinal axis and perpen- "ice dicular to the plane of its rim 25 (a plane through line 3 3 of FIGURE 1 and perpendicular to the plane of the paper) and, accordingly the side areas of the refractor will be described with reference to one of the symmetric parts.

As can be seen from the drawing, the refractor of the invention comprises a concavo-convex structure 26 in the general form of a truncated triangular pyramid. The refractor is divided into areas each having an interior surface and an exterior surface, each of which is provided with several series of parallel refracting or reflecting prisms. Side areas 27 and 28 and base area 29, illustrated in FIGURE 1, contain refracting prisms on both their interior surfaces and their exterior surfaces, while end area 30, which is intended to be placed facing the well upon which the luminaire is mounted, has a smooth interior surface 50 and an exterior surface having thereon a series of prisms 51, illustrated in FIGURE 5, having the ability by means of internal reilection to redirect in the direction of a vertical line through the light center substantially all light from the lightcenter falling directly on surface 50. The configuration of such totally reccting prisms is well known in the art and, for that reason, will not be further discussed.

Side areas 27 and 28 of the refractor will be described with reference to area 27, it being understood that area 28 is symmetric therewith and functions similarly.

It is a function of the side areas to direct most of the light from the luminaire along the ground adjacent to the wall upon which the luminaire is mounted. Since it is an object of the invention to spread light on the ground along the length of the wal-l, for example, along a sidewalk near the wall, the luminaire is designed to emit the greatest amount of light at horizontal angles approximate- 1y 16 from the wall surface and at vertical angles approximately 72 above nadir.

This light distribution is illustrated in FIGURES 18 and 19. FIGURE 18 gives the lateral distribution of candle power values for light emitted from the luminaire in a cone having its apex at the light center and having its surface 72 about nadir, that is the light rays form angles of 18 with the horizontal. The luminaire is mounted with its longitudinal axis along the 0 line on the diagram, and the candle power curve is seen to form a pattern which is substantially symmetric about this line and which gives maximum candle power ratings at angles of approximately 74 on each side thereof. FIGURE 19 gives the vertical candle power Values for the same luminaire for 74 lateral, that is, the candle power distribution through from nadir to zenith in each of two vertical planes through the maximum candle power vectors of FIGURE 18 and comprises the substantially symmetric lobes on each side of the 0-l80 line.

In order to effect such distribution the side and the bottom areas are constructed as follows:

Side area 27, which is the area delineated generally by the broken line X-X of FIGURE l, comprises two sections. The first of these is an upper and end section which comprises that portion having on its interior surface a plurality of prisms generally perpendicular to rim 25 of the refractor, as indicated in FIGURE 1. These prisms are shown as

prisms

61, 121, and 141 of FIG- URES 6, l2, and 14 respectively, and have their bases, or their thickest portions, at their edges which are nearest to a central bullseye area, designated as 32 in FIGURE 1. Thus, light rays passing through this section tend to be bent in the direction of this central area. Since greater refractive power is required to bend in this direction light which falls nearer the ends of this section, the prisms increase in pitch with increasing distance from the central area. Central area 32 corresponds to the 74 lateral angle referred to in reference to FIGURES 18 and 19. On the exterior surface of this section is a plurality of

prisms

131 and 151, generally parallel to rim 25 and illustrated respectively in FIGURES 13 and 15. These prisms have their maximum thicknesses at their edgeswhich are farthest from rim'l 25 and therefore bend light iri directions away from the rim.

The second section of side area 27, which will be referred to as the lower section, has an interior surface having a series of prisms generally parallel to rim 25, as shown in FIGURE 1v. The configurations of these prisms are illustrated as

prisms

81 and 101 of FIGURES 8 and 10, respectively. These prisms have their thickest edges nearest rim 25 and hence tend to bend light in the direction of the rim. On the exterior surface of this lower section is a series of prisms having an arrangement similar to that of

prisms

121 and 141 of the interior surface 0f the upper and end section of area 27.V They are generally perpendicular to rim 25 and have their thickest edges nearest a central area which is a continuation of area 32 of FIGURE l and tend to cause light to converge in this direction. They are illustrated as prisms 91 and 111 of FIGURES 9 and l1 respectively.

Base area 29, having its interior and exterior surfaces illustrated in plan view in FIGURES 1 and 4 respectively, refracts light away from the area directly beneath the luminaire and spreads it away from and beside the wall on which the luminaire is mounted. On the interior surface of base area 29 are a plurality of prisms 71, illustrated in section in FIGURE 3', and generally parallel to the surfaces of end area 30. Prisms 71 are thickest at their edges farthest from an area 30 and hence refract light away therefrom. The refractive power of the prisms decreases with increasing distance from base area 30. The exterior surface of base area 29 is divided into three sections, illustrated in section in FIGURES 7, 16 and 17 respectively. The prisms 70 of FIGURE 7, which together with that part of the interior surface opposed thereto comprise the forward section of the base area, have slightly curved surfaces and consequently spread out the light passing therethrough by causing light rays to be bent in the direction of the centers of the respective prisms and subsequently to cross and diverge. The inclination ofthe surfaces of prisms 70, which are thickest at their edges farthest from the longitudinal axis ofthe refractor, increases with increasing distance from the center, and hence the cumulative effect of

prisms

70 and 71 is to cause light emitted from this section to be spread overa wide area below and in front of the luminaire. Prisms'160 and 170 of FIGURES 16 and 17 respectively, which together with that part of the interior surface opposed thereto comprise the base section of base area 29, are oriented at angles of approximately 45 with the longitudinal axis of the luminaire and are thickest at their edges -farthest from end area 30. Their function is to bend outwardly from the wall and laterally from the luminaire light which would otherwise fall on the wall or directly under the luminaire.

It will be observed that the term prism is not used herein in its strict geometric sense, since the structures so described are not composed solely of plane surfaces but are of necessity curved to fit the curved surface areas of the refractor. VIn addition, as has been pointed out, certain prisms have refracting surfaces which are curved in cross section as well.

Side areas 27 and 28 are formed with two sections as described in order to avoid angular configurations which would make it impossible to remove the finished refractor from a one-piece block mold. It will be apparent to those familiar with the art that, if it is desired to use a separable mold, the side areas may equally well be made with all horizontally deecting prisms on one surface and all vertically -deecting prisms on one surface and all vertically deecting prisms on the other surface.

It will be further apparent that end area 30 may comprise a reflecting surface such as a silvered surface rather than the illustrated totally reilecting prisms.

In order to direct the main beam from the luminaire at 74 in a horizontal direction from the longitudinal axis of the luminaire, the light center of the luminaire is placed so that the vertical bulls eyes, toward which the vertical prisms of the side and end areas refract light, and the longitudinal axis subtend angles of 74 at the light center. It will be understood, however, that modifications in the precise light distribution illustrated may be eifected Within the scope of the invention by variation of the location of the light center within the luminaire.

I claim:

1. A refractor in the generalr shape of a hollow truncated triangular pyramid having an open base forming a rim, and comprising an end area on one generally quadrangular face thereof, two symmetric side areas on the remaining generally quadrangular faces thereof, and a base area on the generally triangular face thereof, each of said side areas comprising two sets of surface prisms, the prisms of one of said sets having edges substantially parallel to said rim and having bases nearest a line on their respective side area substantially parallel to said rim and the other of said sets having edges substantially perpendicular to said rim and having base edges nearest a line on their respective side area substantially perpendicularv to said rim, said end area having a reflecting surface, and said base area comprising four sets of surface prisms, the rst set comprising a series of prisms having edges substantially parallel to said end area of said refractor and having bases at their edges farthest from said end area, the second set comprising a series of parallel prisms having edges substantially perpendicular to said end area and having surfaces which are curved in cross section, and each of said third and fourth sets comprising a series of parallel prisms, the prisms of said third and fourth sets having edges substantially perpendicular and forming angles of approximately 45 with the prisms of said iirst and second sets.

2. A refractor according to claim l in which said second set of base area prisms have base edges farthest from a line in said base area which is substantially perpendicular to said end area and which divides said base area into two substantially equal parts.

3. A refractor in the general shape of a hollow truncated triangular pyramid having an open base forming a rim, and comprising an end area on one generally quadrangular base thereof, two symmetric side areas on the remaining generally quadrangular faces thereof and a base area on the generally triangular face thereof, each of said side areas comprising two sets of surface prisms, the prisms of one of said sets having edges Substantially parallel to said rim and having base edges nearest a line on their respective side area substantially parallel to said rim and the other of said sets having edges substantially perpendicular to said rim and having base edges nearest a line on their respective side area substantially perpendicular to said rim, said end area having a reflecting surface, and Vsaid base area comprising a forward section and a base section, said base area having on its interior surface a series of prisms having edges substantially parallel to said end area of said refractor and bases at their respective edges farthest from said end area, said forward section having an exterior surface comprising a series of prisms having edges substantially perpendicular to said end area and having surfaces which are curved in cross section, and said base section of said base area having an exterior surface comprising two series of parallel prisms, the edges of prisms of each of said series being respectively perpendicular to the edges of the prisms of the other of said series and forming angles of approximately 45 with the edges of said prisms of the exterior surface of said forward section of said base area, and having bases at their edges farthest from said end area.

4. A refractor according to claim 3 in which said end area has a smooth interior surface and an exterior surface comprising a series of parallel internally reecting prisms having edges generally perpendicular to said rim.

5. A refractor according to claim 3 in which the said prisms of the exterior surface of the forward section of the base area have base edges farthest from a line in said base area which line is substantially perpendicular to said end area and divides said base area into two substantially equal parts.

6. A refractor according to claim 3 in which each of said side areas comprises a lower section and an upper and end section, said lower section having an interior surface comprising a series of prisms having edges substantially parallel to said rim and having base edges nearest said rim and an exterior surface comprising a series of prisms having edges substantially perpendicular to said rim and having base edges nearest a line substantially perpendicular to said rim and dividing said side area into two parts, and said upper and end section having an exterior surface comprising a series of prisms having edges substantially parallel to said rim and having base edges farthest from said rim and an interior surface comprising a series of prisms having edges substantially perpendicular to said rim and having base edges nearest said line dividing said side area into two parts.

References Cited in the file of this patent UNITED STATES PATENTS 804,254 Mygatt Nov. 14, 1905 1,731,714 Dorey s Oct. 15, 1929 2,739,226 Rex Mar. 30, 1956 2,814,723 Franck et al. Nov. 26, 1957

Claims

1. A REFRACTOR IN THE GENERAL SHAPE OF A HOLLOW TRUNCATED TRIANGULAR PYRAMID HAVING AN OPEN BASE FORMING A RIM, AND COMPRISING AN END AREA ON ONE GENERALLY QUADRANGULAR FACE THEREOF, TWO SYMMETRIC SIDE AREAS ON THE REMAINING GENERALLY QUADRANGULAR FACES THEREOF, AND A BASE AREA ON THE GENERALLY TRIANGULAR FACE THEREOF, EACH OF SAID SIDE AREAS COMPRISING TWO SETS OF SURFACE PRISMS, THE PRISMS OF ONE OF SAID SETS HAVING EDGES SUBSTANTIALLY PARALLEL TO SAID RIM AND HAVING BASES NEAREST A LINE ON THEIR RESPECTIVE SIDE AREA SUBSTANTIALLY PARALLEL TO SAID RIM AND THE OTHER OF SAID SETS HAVING EDGES SUBSTANTIALLY PERPENDICULAR TO SAID RIM AND HAVING BASE EDGES NEAREST A LINE ON THEIR RESPECTIVE SIDE AREA SUBSTANTIALLY PERPENDICULAR TO SAID RIM, SAID END AREA HAVING A REFLECTING SURFACE, AND SAID BASE AREA COMPRISING FOUR SETS OF SURFACE PRISMS, THE FIRST SET COMPRISING A SERIES OF PRISMS HAVING EDGES SUBSTANTIALLY PARALLEL TO SAID END AREA OF SAID REFRACTOR AND HAVING BASES AT THEIR EDGES FARTHEST FROM SAID END AREA, THE SECOND SET COMPRISING A SERIES OF PARALLEL PRISMS HAVING EDGES SUBSTANTIALLY PERPENDICULAR TO SAID END AREA AND HAVING SURFACES WHICH ARE CURVED IN CROSS SECTION, AND EACH OF SAID THIRD AND FOURTH SETS COMPRISING A SERIES OF PARALLEL PRISMS, THE PRISMS OF SAID THIRD AND FOURTH SETS HAVING EDGES SUBSTANTIALLY PERPENDICULAR AND FORMING ANGLES OF APPROXIMATELY 45* WITH THE PRISMS OF SAID FIRST AND SECOND SETS.