US3466437A

US3466437A - Refractor

Info

Publication number: US3466437A
Application number: US591834A
Authority: US
Inventors: Donald E Ruehl
Original assignee: Holophane Corp
Current assignee: Holophane Corp
Priority date: 1966-11-03
Filing date: 1966-11-03
Publication date: 1969-09-09
Anticipated expiration: 1986-09-09

Description

D. E. RUEHL sept. 9, 1969 REFRACTOR 2 Sheets-Sheet l Filed Nov.

INVENTOR Donald E', Puch( meh i ma@ ATTORNEYS D. E. RUEHL 'REFRACTOR Sept. 9, 1969 2 Sheets-Sheet 2 Filed Nov.

Eonald E. Pue/l 7700!@ Waele ATTQRNEY United States Patent O REFRACTOR Donald E. Ruehl, Newark, Ohio, assignor to Holophane Company, Inc., New York, N.Y., a corporation of Delaware Filed Nov. 3, 1966, Ser. No. 591,834

Int. Cl. F21v 5/00 U.S. Cl. 240-106 11 Claims ABSTRACT F THE DISCLOSURE A bottom for a normally open-bottom refractor to control down light from the light source provides diffusion of light along parallel lines within wedge-shaped sections of flutes with the central flute of each wedge-shaped section extending radially and theremaining flutes of each section extending parallel to the central flute, thereby providing light obscuration via parallel diffusion of the varied angles of light emanating from the light source. The bottom also provides annular concentric flutes in the center of the bottom and a system of annular concentric prisms outwardly thereof performing light-depressing functions. The bottom may be removable, and in this respect, clips are provided for disposing the bottom above the lower edge of the refractor to provide an optically closed, but thermally opened bottom permitting ventilation of the refractor by convection.

The present invention relates to refractors for luminaires and, more specifically, to prismatic bottoms for refractors.

For many years, in the art of designing area luminaires, the open bottom variety was favored over the enclosed type for several reasons. The prime consideration was the ease with which the lamp could be replaced-since earlier lamps had relatively short lives compared to the new lamps. A man on the ground with a pole changer could relamp a fixture in a fraction of the time it would take someone to climb the pole and open and relamp the fixture.

Of course, With the acceptance of the cost savings feature of the open bottom, one accepted the fact that the light coming through the open bottom could no be controlled. Moreover, if luminaires with such open bottom refractors are employed for street lighting, there exists a great tempetation for vandals to break the lamps by throwing stones or other objects into the refractor because the lamp is not obscured and the location of the lamp can easily be determined.

It is an object of the present invention to provide a refractor for luminaires, which will make it possible to control the light passing through the lower portion of the refractor.

It is another object of the present invention to provide a refractor of the type set forth in the preceding paragraph with a bottom having flutes on the light incident side and prism formations and flutes on the light emergent side which will result in a desirable light distribution, i.e., a substantially uniform distribution over a wide angle range.

This object has been realized by a substantially circular bottom the inner or light incident surface of which consists of wedge-shaped sections of utes with the central flute of each wedge-shaped section extending radially and the remaining flutes of each section extending parallel to the central flute of the respective section while the light emergent surface of the bottom consists of a system of annular concentric flutes in the center of the bottom and a system of annular concentric light depressing prisms on the remaining outer portion of the light emergent surface. These depressing prisms become increasingly deeper towards the center of the bottom.

Further objects and features of the invention will ap- Patented Sept. 9, 1969 "ice pear more clearly from a study of the specification and the drawings, in which:

FIG. l is a section through a prior art open botto-m refractor;

FIG. 2 diagrammatically illustrates the relative candlepower distribution in a vertical plane of the refractor of FIG. l;

FIG. 3 is a section through a refractor with a closed bottom designed in conformity with the present invention;

FIGS. 4 and 5 are top views of sections of the light incident emergent surfaces respectively of the bottom;

FIG. 6 is a section through a portion of the bottom, on a larger scale than FIG. 3;

FIG. 7 shows the relative candle-power distribution of the refractor of FIG. 3;

FIG. 8 shows a modified refractor bottom according to the present invention; and

FIG. 9 is a cross-section through still another refractor designed in conformity with the invention.

Referring now to the drawings more in detail, FIG. l illustrates a section through a luminaire according to the prior art. This luminaire comprises a light source 1 mounted in a socket 2, and also comprises a refractor 3 with a side wall 4 and an open bottom 5. Side wall. 4 is provided with a series of annular prisms depressing light emanated from light source 1 in a downwardly direction. A refractor of the type shown in FIG. 1 causes a candlepower distribution as shown in FIG. 2. It will be obvious that with angles below 50 the light cannot be controlled since the bottom is open. Therefore, the quite unfavorable candle-power distribution as shown in FIG. 2 is obtained in the range below 50.

FIGS. 3 to 6 illustrate the refractor according to the present invention. Refractor 3a shown therein comprises a side wall 4 of the same design as shown in FIG. 1. However, the new refractor is equipped with a bottom 6 of a particular design. The top or light incident surface of bottom 6 consists of six wedge-shaped sections 7 (only onequarter of this surface is shown in FIG. 4). The central flute 8 of each wedge-shaped section 7 extends radially outwardly from the center of the bottom while the remaining flutes 9 of each section extend parallel to the central ilute 8 of the respective section. The lower or light emergent surface of bottom 6 consists of a system of annular concentric flutes 10 in the central portion of the bottom and a system of annular concentric light depressing prisms 11 on the remaining outer portion of the light emergent surface of bottom 6. As is more clearly shown in FIG. 6, the height of the depressing prisms decreases from the center towards the periphery of bottom 6.

As will be appreciated, the light from the source striking the bottom at various lateral angles will be diffused laterally of the parallel flute paths thus providing not only proper diffusion, but also a light obscuration function.

As will be evident from FIG. 3, when a ray 14 enters the top or light incident surface of bottom 6, it is re- Eracted downwardly and as it leaves the lower or light emergent surface of bottom 6 it is refracted upwardly, the net result being that the

sections

15 and 16 of ray 14 are parallel to each other. All rays below ray 14, as for instance ray 17, upon entering the light incident surface of bottom 6 are retracted downwardly and strike the depressing prisms 11. In other words, the ray section 19 of ray 17 is retracted downwardly and inwardly and never outwardly and upwardly after passing through bottom 6.

The particular design of the flutes and prisms enables the bottom to produce a more uniform distribution of the light since it compensates for lamp output characteristics by adding light to the lower angles. The width of the distribution of the light is no greater than with an open bottom as is clearly evident from a comparison 3 between the candle-power distributions of FIGS. 2 and 7, but the light distribution is considerably more uniform with the refractor according to the present invention.

It might be added that there exists a greater freedom of design with a refractor having a bottom than with a refractor having no bottom since many different shapes can be produced to satisfy a variety of tastes. As an example, a portion of a modified bottom of a refractor is shown in FIG. 8.

Another modified bottom is illustrated in FIG. 9. A bottom 6a having the same configuration of prisms and flutes on the light incident and light emergent side as the bottom illustrated in FIGS. 3 to 6, is formed as a separate member which is held to the main body of the refractor by a plurality of clips 20, for instance three clips (only one being shown in FIG. 9). The bottom 6a is, together Vwith clips 20, inserted into the refractor from the top, which snap into place onto bead portion 21 of the refractor. This type of attached bottom would have the same optical characteristics as a bottom integral with the main body of the refractor but would provide an optically closed, thermally ventilated refractor, if desired. Air could be drawn into the refractor around the open bottom 6a as indicated by arrows 22 in FIG. 9 and could exhaust through an appropriate chimney or opening in the fixture above the refractor.

It is, of course, to be understood that the present invention, is by no means, limited to the particular construction shown in the drawing but also comprises any modifications within the scope of the appended claims. Thus, for instance, for different distributions, flute and prism configurations other than those shown and specifically described in the specification could be employed and could, for example, include both depressing and elevating prisms.

What is claimed is:

1. A refractor for a luminaire having a light source, said refractor comprising: a bottom including tmeans for redirecting down-light from the source, a plurality of wedge-shaped flute sections on the light incident surface of said bottom with the tips of said sections being located in the center of said bottom, each of said sections including a plurality of elongated flutes arranged parallel to each other and to the bisecting line of the central angle of the respective section, said sections of flutes comprising means for receiving light from the source at varying lateral and vertical angles and for diffusing the same along parallel paths within each said section, a plurality of concentric annular flutes on the central portion of the light emergent surface of said bottom and concentric to the center of said bottom, and a plurality of concentric, annular prisms on the remaining portion of the light emergent surface of said bottom, and concentric to the center of said bottom, said concentric prisms constituting means for receiving down light and redirecting the same.

2. A refractor bottom according to claim 1, in which said concentric prisms constitute means for receiving down light and depressing the same.

3. A refractor bottom according to claim 1, in which the height of said prisms increases from the circumference toward the center of said bottom.

4. A refractor according to claim 1, which includes a refractor body, and means for clamping said bottom onto said refractor body.

S. A refractor according to claim 4, in which said refractor body diminishes in circumference from the top toward the bottom edge thereof and said clamping means are formed by snap spring means for interconnecting said bottom edge of said refractor body at the outer periphery of said bottom, thereby permitting insertion of the bottom into said refractor from the top.

6. A refractor according to claim 4, wherein said means for clamping said bottom onto said refractor bottom also constitutes means for disposing the outer periphery of said bottom in spaced relation to the lower edge of said refractor body whereby said bottom and said refractor body comprise means for thermally Ventilating said refractor.

7. A bottom of a refractor for a luminaire having a light source, said bottom comprising means for redirecting down light from the light source, a plurality of wedgeshaped flute sections on the light incident surface of said bottom with the tips of said sections being located in the center of said bottom, each of said sections including' a plurality of elongated flutes arranged parallel to each other and to the bisecting line of the central angle of the respective section, said sections of flutes comprising me'ans for receiving light from the source at varying lateral and vertical angles and for diffusing the same along parallel paths within each said section, a plurality of concentric annular flutes on the central portion of the light emergent surface of said bottom and concentric to the center of said bottom, and a plurality of concentric, annular prisms on the remaining portion of the light emergent surface of said bottom, and concentric to the center of said bottom, said concentric prisms constituting means for receiving down light and redirecting the same.

8. A refractor for a luminaire having a light source, said refractor comprising a cylindrical body portion for surrounding the light source and redirecting light therefrom both laterally and vertically, a bottom portion including light incident flutes for diffusing light from the source and also including light emergent prisms for redirecting the diffused light, clip means for interconnecting the lower edge of said body portion and the outer periphery of said bottom portion in spaced relation with one another whereby said refractor is optically closed and thermally opened at the bottom thereof.

9. The refractor of claim 8, wherein said cylindrical body diminishes in diameter from the top to the bottom,

the diameter of said bottom being substantially the same as the diameter of the opening at the bottom of said cylindrical body, said clip means including a bottom connecting element attaching to the bottom edge of said body and a top connecting element connecting to the outer periphery of said bottom and a central portion positioning said bottom above the lower edge of said cylindrical body, whereby said bottom may be inserted into said refractor from the top end thereof.

10. The refractor of claim 9, wherein the lower edge of said cylindrical body provides an inwardly extending flange and the lower connecting element of said clip connects the lower edge of said cylindrical body via said flange.

11. A refractor for a luminaire having a light source, said refractor comprising a cylindrical body portion for surrounding the light source and vertically redirecting light therefrom, a bottom portion including light incident flutes for diffusing light from the source and also including light emergent prisms for redirecting the diffused light, means for interconnecting the lower edge of said body portion and the outer periphery of said bottom portion in spaced relation with one another whereby said refractor is optically closed and thermally at the bottom thereof.

References Cited UNITED STATES PATENTS 2,246,320 6/1941 Rolph 24U-106 XR 2,877,342 3/1959 Beach 24U-106.1 XR 2,878,371 3/1959 Hanlin 240- 47 3,020,395 2/1962 Peltz 240-106 3,168,985 2/1965 Troup et al. 240-47 XR 3,340,393 9/1967 Frank et al 24U-93 NORTON ANSHER, Primary Examiner RICHARD M. SHEER, Assistant Examiner Us. C1. x.R. 249147, 93