US2201860A - Luminaire - Google Patents

Description

s. ENGLISH 2,201,860

. May 21, 1940.

' LUMINAJERE.

Filed July 28, 1937 INVENTOR I SOLOMON ENGLISH ATTORNEY Patented May 21, 1940 UNITED STATES LUMINAIRE Solomon English, London, England, assignor to Holophane Company, Inc., New York, N. Y., a corporation of Delaware Application July 28,1937, Serial No. 156,056

' In Great Britain July 31, 1936 8' Claims.

. The present invention relates to improvements in luminaires, particularlystreet lighting luminaires applicable for use in areas which are likel'y to be subject to air raids during war time.

Street lighting luminaires embodying the present invention are designed so as not to give any indication of their existence or location to raiding aircraft and therefore have several essential characteristics which are not found in ordinary street lighting fittings, Some of the more important of these characteristics are an absolute light cut-ofi along or preferably a few degrees below the horizontal; a distribution of the light fairly evenly over the area to be illuminated while particularly avoiding highly illuminated areas, such as are often produced immediately below certain types of street lighting luminaires, and such as would be clearly seen from an aeroplane overhead; and assuming that the luminaire is to be mounted above the curb, a redirection of the light away from buildings in its vicinity and also away from buildings or houses across the other side of the roadway. Further meansmay with advantage be provided for easily changing some portion of the unit in such a way that it gives onlyablue light,- which is suflicient to illuminate the roadway to a low level but which does not permit of discernment from a distance, as for instance from a raiding aeroplane.

The present invention provides street lighting luminaires having the above characteristics and comprises a lantern in which the light source is combined with a downwardly acting specular reflector and a shallow dish or closure member positioned beneath the light source. The closure member may carry refracting or diffusing prisms on the sides and diffusing or refracting prisms on the bottom, while the specular reflector surrounding the light source is adapted to send the reflected light on to the sides of the dish for transmission to light remote to street areas. An

. outer opaque shield or reflector is also preferably provided to give an absolute cut off along or below the horizontal.

Other and further objects of the invention will appear as the description proceeds.

, The accompanying drawing shows, for purposes of illustrating the present. invention, one of the many embodiments in which the invention may take form, together with modifications of certain parts, it being understood that the drawing is illustrative of the invention rather than limiting the same.

- In the drawing:

" Figure 1 is a vertical sectionalview through a street lighting luminaire embodying the present invention; I

Figure 2 is a vertical sectional view through the light controlling element of a modified form of Figures 3 and 4 are fragmentary vertical and horizontal sectional views through a form of luminairev designed for asymmetric lighting; 'and Figure 5 is a fragmentary horizontal section of a modification.

The lamp bulb l0 having the usual filament II is supported from a lamp socket 12 carried in a suitable fitting. The bulb is received in a specular reflector l3, which is secured inside a protecting hood H by means of rings l5 and I! and brackets I 6. j

The reflector extends upwardly from a level slightly below the filament and has a profile to accept a substantial zone of light above the horizontal and reflect it downwardly across the reflector into a beam having substantially less spread than that of the direct rays before reflection (as will be apparent from the rays indicated in the drawing). As the reflector is specular the direction of the reflected rays is accurately controlled and they may pass outwardly and downwardly at high angles above the nadir (the direction on a photometric distribution curve directly beneath the center of the lighting unit) and these rays are well adapted for lighting remote street areas.

The hood It supports a hinge part l8 and this supports the hinge part l9 and pin 20. The hinge part I9 is secured to a flat conical screen and reflector 2| having an inwardly extending. ring like element 22 and held in place by a catch 22. Clips 23 are secured as shown and these parts support a shallow dish or closure member 24 made of pressed glass or equivalent material.

This glass dish, as shown in Figure 1, has slightly conical walls 25 to pass the reflected light rays and a narrow zone of direct light, as indicated. The bottom 26 of the dish is substantially fiat, being either a flat cone or a section of a large diameter sphere. It is preferably provided with some means of redirecting the light rays so as to avoid an excessively bright spot below the luminaire. While a light absorbent coating or other diffusing means may be used, it is preferable to employ light diverting prisms 21, whichniay be annular, radial or parallel prisms arranged across the roadway.

A definite tcut-ofi of the light along or below the horizontal is provided by the opaque reflector or shield 2|, the rim 28 of which when in position comes level with or below the lowest point of the refractor bowl 24. In order not to obstruct light emitted by the sides of the refractor, this shield is inclined only a few degrees below the,

horizontal-perhaps 10. For this. reason the shield or reflector has necessarily a large diameter, and it is largely to avoid the necessity for a. shield with such a diameter as to be unwieldy;

ihlaalighting luminaire that the refractorbowl is kept shallow. The under surface arc-this re- 50 p flector or screen may be white, or if it is necessary to keep the illumination near the foot of the lamp post as low as possible, it may be enamelled gra'y so as to reduce the intensity of the difiusely reflected light, while retaining a high value of specularly reflected light-owing to the large angle of incidence, such specularly reflected light being redirected towards areas at some distance away from the foot of the post.

When a blue light only is desired, a blue glass electric lamp may be used as the light source, but preferably the shallow retracting dish is made of blue glass, since by this means, the emitted light is all filtered once through the blue glass, whereas, if a blue lamp is used, the reflected light may be filtered by passage through blue glass as many as three times.

In the arrangement shown in Figure 2, the bottom closure 24' has annular light depressing prisms 25 which usually will extend part way around the side walls, but they may extend all the way around. Either form of closure may have vertical diffusing flutes, if desired.

Figures 3 and 4 show a modified form of closure or bowl in which the side walls have a system of inside vertical prisms 25" adapted to produce asymmetric distribution to direct the light in the direction of the street.

In Figure 5 the side walls of the dish or bowl are shown as having vertical external reflecting prisms 25".

The light controlling element shown herein may, with suitable modification as to size and socket support, be used in desk lamps having the usual outer ornamental shade.

It is obvious that the invention may be embodied in many forms and constructions within the scope of the claims and I wish it to be understood that the particular form shown is but one of the many forms. Various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

What is claimed is:

l. A luminaire comprising a light source, a downwardly acting specular reflector about the source and of a profile to accept a substantial zone of light extending upwardly from the horizontal and reflect it downwardly across the reflector axis into a beam having a substantially less angle of spread than that of the direct rays before reflection, the reflected rays being at high angles above nadir for lighting remote areas, and a transparent member disposed below the reflector and having side walls to pass both the reflected rays and a narrow zone of direct light and a bottom wall which intercepts downwardly emitted direct light and redistributesiit to avoid high brightness of the surface directly below the luminaire.

2. A luminaire comprising a light source, a downwardly acting specular reflector about the source and of a profile to accept a substantial zone of light extending upwardly from the horizontal and reflect it downwardly across the reflector axis into a beam having a substantially less angle of spread than that of the direct rays before reflection, the reflected rays being at high angles above nadir for lighting remote areas, and a transparent member disposed below the reflector and having side walls to pass both the reflected rays and a narrow zone of direct light and a bottom wall, provided with prisms which intercept downwardly emitted direct light and spread it away from nadir to avoid high brightness of the surface directly below the luminaire.

3. A luminaire comprising a light source, a downwardly acting specular reflector about the source for reflecting light rays across the reflector axis at controlled high angles above nadir for lighting remote areas, and a transparent member disposed below the reflector and having side walls provided with substantially vertical prisms which act on both the reflected rays and a narrow zone of direct light to produce an asymmetric distribution in horizontal planes, and a bottom wall which intercepts downwardly emitted direct light and redistributes it to avoid high brightness of the surface directly below the luminaire.

4. A luminaire comprising a light source, a downwardly acting specular reflector about the source for reflecting light rays across the reflector axis at controlled high angles above nadir for lighting remote areas, and a transparent member disposed below the reflector and having side walls to pass both the reflected rays and a narrow zone of direct light, at least a portion of said side walls having annular prisms to lower the rays emitted therefrom, and a bottom wall which intercepts downwardly emitted direct light and redistributes it to avoid high brightness of the surface directly below the luminaire.

5. A luminaire comprising a light source, a downwardly acting specular reflector about the source for reflecting light rays across the reflector axis at controlled high angles above nadir for light remote areas, a transparent member disposed below the reflector and having side walls to pass both the reflected rays and a narrow zone of direct light and a bottom wall' which intercepts downwardly emitted direct light and redistributes it to avoid high brightness of the surface directly below the luminaire, and a screen about the transparent member, the lower edge of the screen being below the bottom of the transparent member and above the path of the high angle direct and reflected rays.

6. A luminaire comprising a light source, an open mouthed specular reflector extending slightly below the light source and reflecting light rays across the reflector axis at controlled high angles above nadir for lighting remote areas, a downwardly and outwardly flaring screening member disposed just above the reflected light rays so as not to interfere with them, and a lower closure member having transparent side walls to pass the reflected light rays and a narrow zone of direct light and a substantially flat bottom wall which is above the opening in the screen so that the entire bottom member is screened at angles above the horizontal.

7. A luminaire as in claim 6, wherein the bottom wall of the closure member has annular prisms to spread light away from nadir.

8. A street lighting luminaire comprising a pendant lamp socket, a lamp bulb, a socket support, a downwardly opening hood about the bulb, a specular reflector secured inside the hood and adapted to reflect light across the reflector axis for lighting remote street areas, a downwardly and outwardly flaring screening member detachably secured to the mouth of the hood and disposed above the reflected light rays so as not to interfere with them, the screening member extending inwardly adjacent the mouth of the reflector, and having a central aperture, and a. closure member for said aperture, the bottom of the closure member terminating above the plane of the mouth of the screening member.

SOLOMON ENGLISH.

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