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Патент USA US2109990

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March 1, 1938._
Filed June 26, 1936
, sumac/0A1.
PARA 90.410041.
Harold J. Flahef‘tg.
by ?/w/jé‘jwjw
Patented vMar. 1, 19.38
Harold J. Flaherty, Scum, Mara, “Signor to
General Electric Company, a corporation of
New York
Application June 26, 1936, Serial No. 87,470
4 Claims. (01. 240—.-2_5)
My invention relates to luminaires, and more
particularly to street-lighting luminaires. '
One object of my invention is to provide an‘
improved re?ector whereby a substantially uni
5 form distribution of light may be obtained over
a predetermined area.
For a better understanding of my invention,
together with other and further objects thereof,
reference is had to the following description.
it) taken in connection with the accompanying
drawing, andits scope will be pointed out in the
appended claims.
In the accompanying drawing, Fig. 1 is a ver
tical cross~section view of a luminaire equipped
ill with my improved re?ector, and Fig. 2 is a -par--.
tial view of a modi?ed luminaire also equipped
with my improved re?ector.
_ "
?ected from the ‘sections of the re?ector nearer
to the zenith are re?ected at such low angles
that the light strikes the surface near the lumi
naire where it raises the light intensity above the '
desired value, or it strikes the opposite edge of 5
the re?ectorthereby being confined within the
re?ector. ‘In accordance with my invention the
surface of thefre?ector is given a curvature such
as to ‘project the maximum of light to the edge
of the beam and a supplementary surface con- 10
focal with the continuous surface is provided to
project additional light towards the edge of the '
The re?ector in. the illustrated luminaire is a
surface'of revolutioncomprlsing a paraboloidal 15
surface having its axis tilted to the horizontal by
abont:1,5°. ' The axisof this section of the re- '
In the luminaire of Fig. 1, a light source I, ?ector is ‘indicated by a line H. The section ex
such as an incandescent ?lament lamp, for‘ ex ~tends between ?ange‘ 9 and a line indicated by
20 ample, is the light source'and is supported in a - point ii. in the drawing.
socket 2, which in turn is mounted in a porcelain
cap 3: A conductor 4 conducts current to’the
terminals of the socket 2 through a receptacle 5.
The light source is enclosed by a housing com
25 prising a sheet metal re?ector ‘I and a glass globe
8. The re?ector is provided at its lower end with
a ?ange 9 which is preferably spun over the edge
of the globe 8 for the purpose of- providing a
dust-proof joint between the re?ector and globe.
30 The housing is attached to the cap. by means of
latches comprising rings l0 engaging lugs II on
a metal collar l2 surrounding the cap 3 near its
lower edge. This collar I2 is provided with a' cap
‘03 by means of whichit may be attached to any
35 convenient pipe and thereby support the entire
In luminaires of the type disclosed, the re?ector
' is designed to collect substantially all light pro
jected by the source above the horizontal and to
40 re?ect it towards the surface over which it isv
suspended. The di?lculty has been to distribute
the re?ected light in such manner that when the.
re?ected light is combined with the direct light
from the source, a uniform intensity is obtained
45 over the entire ‘area. In view ofthé high in
tensity of the direct light, directly below the
luminair, it becomes necessary to project prac
tically all the re?ected light to the edge of the
illuminated area. This has been impossible with
. 50 the conventional continuous surfaced re?ectors
having the conventional curvatures and dimen-,
sions. The main reason for this limitation is that
only a comparatively narrow section of the re
?ector surface could be used to re?ect light at
55' the-angles nearest to horizontal. The light re
This re?ector section 20
projects a parallel beam bounded by the lines l6
and l‘l. '‘ Line It represents the upper edge of
this beam and indicates that it passes under the
opposite ‘edge of. the .re?ector. The resulting
beam‘ from thissection of the re?ector surface is 25
a conoid .‘with its apex at the center It of the
light ‘source I.
"It isevident that if the paraboloidal surface
were continued above the indicated line l5, the
light a'boire that line would be cut of! by the op- 30
posite edge of the-re?ector. A greater proportion‘
of‘pthe upwardly'projected light, therefore, can
not be projected by a paraboloidal section with
out changing the angle of the axis l4 or increas
ing the diameter of the re?ector. A partial solu-' 35
tion of this problem is obtained by continuing the
surface of the re?ector as an ellipsoid having its
' conjugate feel at the center I! of the light source
_ and at a point l9 which is below the edge of ?ange
‘9; and outside of the-glass globe 8. This surface 40
extends from the. edge l5 of the paraboloidal sec
tion' up to a line 20. This surface is extended as
far as possible upwardly toward the zenith with
out projecting light against the ?ange 9. The
light from this re?ector section is concentrated ‘45
at the locus of foci l9 and is then added to the
light projected by the paraboloidal section. The
surfaces so far described still leave a large por
tion of the upwardly projected light unre?ected.
A continuation of the ellipsoidal surface would 50
partially take care of this problem, but that
would result in an increase of the length of the
luminaire. or would necessitate an increase in
diameter. This is undesirable.
In accordance with my invention, I terminate 55
the ellipsoidal surface, thereby creating in effect,
1. In a street-lighting luminaire, the combina
a complex frustro-conoid and provide a second I tion of a main re?ector, a light source, and .an
ellipsoidal re?ector 2|, confocal with the upper
section of the main re?ector, but having shorter
focal lengths so that it may be placed nearer to
the light source. In- the drawing, this second re
' ?ector 2| is illustrated as being concentric with
the main-re?ector ‘I and having an average diam
eter which passes its reflecting surface from the
v10 main re?ector surface toward thecommon axis.
auxiliary re?ector, arranged within said main
re?ector to intercept light outside of the collect
ing angle of said main re?ector and tore?ect
said light into the beam projected from said ?rst
re?ector, said ?rst re?ector having a focal point
at the center of the light source and a second
focal point outside of said re?ector, said auxiliary
re?ector having foci coinciding with said foci of
The main re?ector is provided with a reducing said ?rst re?ector but having. at least one of its
?ange 12, towhich the rings III are fastened, and , corresponding focal lengths shorter than that of
also a collar 28. The collar 28 is concentric with the ?rst re?ector.
the main re?ector and projects above the ?ange
2. In a luminaire, the combination of a frustro
15. 22 into the lower end of cap 8. The second re
conoidal re?ector comprising a surface of revo
?ector 2i is provided with a collar 24 which pro
lution including a paraboloidal and ellipsoidal
jecting above the re?ector, ?ts inside of the collar surface joined end to end, and a complementary
23 and thereby supports this complementary re
re?ector comprising an ellipsoidal section
mounted within and concentric with said main
The re?ector 2|, as stated above, is ellipsoidal re?ector outside of the collecting angle of said 20
and is confocal with the main re?ector surfaces. ?rst re?ector andv provided with a surface con
It extends into the main re?ector between the focal with said ?rst ellipsoidal section but having
surface of this re?ector and the axis thereof so at least one shorterv focal length than the corre
as to intercept a substantial portion of the light sponding focal length of said ellipsoidal section.
25 from the source projected between the upper edge
3. In a luminaire, the combination of a lamp, a
20 of the main re?ector and the edge of socket 2. socket therefor and a frustro-conoidal re?ector
With this complementary re?ector, I am, there
comprising a surface containing an ellipsoidal
fore, able to intercept, nearer to the source, and and a paraboloidal section arranged to form a
re?ect into the beam re?ected by the main re
continuous surface, and a second re?ector com
?ector a substantial portion of the upwardly pro
prising an ellipsoidal ?ange concentric withsaid
jected light at the greater angles, that is, light re?ector, said ?ange being confocal with the said
projected nearer to the vertical axis and I am able ellipsoidal section of said continuous surface and
to do this without an increase in the- size of the arranged to intercept an arc of the projected light
extending from the upper edge of the main re
In Fig. 2 I have illustrated a modi?cation‘of ?ector and toward the axis of said main re?ector
the porcelain cap 3. - In this modi?cation the por
and projected into the main beam below the edge
celain cap. 25 is made larger so as to accommodate of the lamp socket.
a supporting collar 26 above a rain shield 21. A
4. In a luminaire, the combination of a light
beading 28 prevents the cap from slipping out of source, a re?ectorvcomprising a surface of revolu
40 the collar. A metal adapter 20 is held into the. tion having an axis projecting through saidlight 40
lower end of the cap by screws 30 and the re?ector source and including an elliptical section, the
‘I is attached to the adapter by ring latches iii, axis of said ellipse being at an angle to the axis
the same as in Fig. 1.
of the surface of revolution and the'conjugate foci
The glass globe 8 may be made of any suitable ,of said section being respectively at the center of
said light source and outside of said re?ector, and
fusing prisms ll on the outer surface of the globe. an auxiliary re?ector ‘confocal with said section
Any suitable prism may be used for diifusing and having at least one shorter focal length arranged
refracting light on either the inner surface or the to intercept light between the edge of said ellip
outer surface thereof.
tical section and the axis of said surface of revo
What I claim as new and'desire to secure by
Letters Patent of the United States is: - I
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