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Патент USA US3047726

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July 31, 1962
J_ P, Hoxn: ETAL
Filed Jan. 31, 1961
JbH/v P flax/E
United States Patent Of?ce
Patented July 31, 1962
zontal length of the ?lament is that light emerging from
John P. Hoxie and Franklin M. Neal, Corning, N.Y., as
signors to Corning Glass Works, Corning, N.Y., a cor
poration of New York
Filed Jan. 31, 1961, Ser. No. 86,208
2 Claims. (Cl. 240—1.2)
the lens is spread over a few degrees in a horizontal plane,
the spread depending upon the length of the ?lament and
its distance from the lens. This small spread is desirable
in order to render the signal visible from positions slightly
off the sides of the runway. Variations in ?lament size
and distance may be offset by Variations in the horizontal
curvature of re?ecting surface 14.
The effect of lens 12 on the vertical orientation of light
The present invention relates to a luminaire which is
adapted to be recessed substantially flush with a surface 10 rays originating at the center of ?lament 11 can be seen in
such as an airport runway and which is capable of emit
FIG. 2. Rays 20 and 21 are refracted at entrance surface
ting light at low angles of elevation above such surface.
13, are re?ected from surface 14 and emerge at angles of
It has generally been the practice to delineate airport
elevation of 1° and 8° respectively after being refracted
runways at night by means of two rows of lights located
at exit surface 15. The lens is adapted to bend rays in
one at each edge of the runway and projecting substan 15 termediate between rays 20 and 21 through angles varying
tially thereabove. Recent conditions of increased air
between 1° and 8°.
traffic have indicated the advisability of placing lights in
Lens 12 is recessed almost completely beneath the level
the runway surface itself in order to render the runway
of the surface of the runway. A convenient means for
more easily visible from the air.
embedding the lens in a runway and at the same time in
In the construction of luminaires adapted for such use, 20 suring that most of the rays emitted from exit surface 15
it has been a problem to design units capable of directing
light at low angles of elevation along an incoming ?ight
path and at the same time sufficiently nearly ?ush with the
are utilized is provided by mounting unit 25, illustrated in
‘FIGS. 3 and 4. This unit comprises a cylinder having a
height approximately equal to that of lens 12 and a diam
runway surface so as to permit airplanes to taxi along the
eter su?icient to permit inclusion of the lens and light
25 source 11 in a cavity in the mounting unit. Lens 12 ex
runway Without being subject to excessive vibration.
It has also been a problem to design a unit su?iciently
tends above the top surface of the mounting unit 25 only
compact to permit installation in presently existing run
by an amount su?icient to present a substantial viewing
ways with a minimum of excavation.
surface at low elevations above the runway surface, which
The luminaire of the present invention has among its
is substantially ?ush with the upper surface of the mount
objects the satisfaction of the above requirements.
ing unit when the unit is in position. It is unnecessary
In general, these objects are accomplished by the pro
that all of exit surface 15 extend above the runway sur
vision of a luminaire comprising a lens with a light source
face level since, as indicated in FIG. 2, those rays which
on the approach side of a lens, the lens including an en
are directed at low angles of elevation are emitted near the
trance surface, a re?ecting surface, and an exit surface,
top of the exit surface, while the lower portion of said
said luminaire being positioned so that the two ?rst-men 35 surface directs light at higher angles, at which angles ob
tioned surfaces are substantially beneath the level vof the
struction from the rim of mounting unit 25 or the surface
runway surface and the last-mentioned surface is only
of the runway is less of a problem.
partially above the said level but completely exposed to
Light source 11 is positioned within the cavity of mount
ing unit 25‘ and ‘on the approach side of lens 12, which
The construction of one embodiment of a luminaire ac
side is the side from which a landing airplane approaches
cording to the present invention may best be considered
the luminaire. A transparent cover 26 may complete the
with reference to the accompanying drawings, wherein:
enclosure of light source 11 and prevent the accumula
FIG. 1 is a perspective view of a lens and light source
tion of deposits in the cavity.
according to the present invention,
It can be seen that only a small portion of the light
FIG. 2 is a sectional view taken along line 2—2 of 45 emitted from source 11 is directed within the desired
FIG. 1,
range. The efficiency of the device can be improved by
FIG. 3 is a top view of one form of a luminaire adapted
placing a re?ector behind the light source. It will also
for seating in a cylindrical hold in a runway, and
be observed that some light will enter the lens at angles
FIG. 4 is a view taken through line 4-—4 of FIG. 3.
50 outside the range between the angles of rays 20 and 21.
The construction of the novel lens employed in the pres
These rays will emerge from the lens in various directions
ent luminaire is illustrated in FIGS. 1 and 2. Light from
but the intensity in any given direction will be low.
source 11 enters lens 12 through entrance surface 13, is
It will be readily seen that the advantages of the present
re?ected from re?ecting surface 14, which is a coating of
invention will accrue even though variations are made in
silver or any other re?ecting substance, and emerges from 55 the exact con?guration of the luminaire. A cylindrical
exit surface 15.
mounting unit has been chosen because of the ease with
In the illustrated embodiments, entrance surface 13 and
which circular holes may be formed in a runway. It is
exit surface 15 are plane surfaces, entrance surface 13 be
apparent that no arbitrary dimensions may be given to
ing vertical, and re?ecting surface 14 is curved in both
lens 12 and that various combinations of shapes of en
horizontal and vertical directions such that, when the light 60 trance, re?ecting and exit surfaces within the spirit of the
source is considered to be a point, the cumulative effect of
present invention will produce the desired pattern of
the three surfaces is to collimate the emergent rays hori
emergent light.
zontally and to spread them vertically over angles of ele
The range of elevation of the emergent rays in the illus
vation above the horizontal varying continuously from 8°
embodiment has been chosen to be between 1° and
for those rays emerging near the bottom of exit surface
present conditions of air tra?ic indicate this range
15 to 1° for those rays emerging near the top of that sur
to be optimum. Under changed conditions, this range
face. These angles are illustrated in FIG. 2 by the angles
may be varied by changes in the con?guration of lens 12
b and a respectively. In other embodiments curved and
within the spirit of the invention. The exact con?gura
plane surfaces may be interchanged.
In the illustrated embodiment light source 11 is in the 70 tion of lens 12 can easily be determined to satisfy varying
requirements by those skilled in the art according to well
form ‘of a horizontal linear ?lament positioned parallel to
known mathematical and optical laws.
entrance surface 13. A consequence of the ?nite hori
Accordingly, it is intended that the present invention be
limited only by the scope of the appended claims.
What is claimed is:
1. A luminaire ‘for directing light through a range of
low angles of elevation above a horizontal surface com
prising .a light source located below the level of said hori
zontal surface and a lens extending from slightly above
saidvhorizontal surface to a level silghtly below said light
side of said lens opposite said light source, said re?ecting
surface being curved in both horizontal and vertical di
rections, said lens spreading light from said source ver
tically through angles of elevation above said horizontal
surface varying continuously from a maximum for light
emerging near the bottom o? said exit surface to a mini
mum for light emerging near the top thereof.
2. A luminaire according to claim 1 wherein ‘said re
?eeting surface substantially collimates horizontally the
source, said lenscompr-ising an entrance surface located
on the same side of said lens as said light source positioned 10 light from said light source falling thereupon.
to receive light rays therefrom, an exit surface located on
References Cited in the file of this patent
the same side of said lens as said light source and at the
top oftsaid lens and forming an acute angle with said hori
zontial surface when measured in the direction away from
said light source, and a re?ecting surface located at the 15
Great Britain __________ __ Oct. 24, 1956
Great Britain ________ __ Oct. 24, 1956
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