Note: Descriptions are shown in the official language in which they were submitted.
l 3~ 2
The present invention relates to a lighting fixture and
particularly to a lamp or 1ashlight ~especially a tail light,
safety lamp-or signal lamp) having a light source, a main
re~lector andan assistant or auxiliary reflector disposed
coaxially to one another and having dif~erent parameters and
different focal regions.
Such a lamp has become known heretofore Erom French Patent
747 832 to Fraise. In this heretofore known lamp, at least
two separate light sources are provided and selectively switched
on; these separate light sources selectively produce a parallel
bright light such as a driving light or, an a weakly diffused,
illuminated background, a ring-shaped light beam which forms
such a sharp contrast with respect to the background that the
illumination is very ill-suited for identifying objects. This
` heretofore known lamp is especially inadequate for meeting the
hereinafter explained requirements of signal lamps or the like.
; The light beàm of a signal lamp or the like should ~for
.
example, according to Gèrman code or regulations) at least
illuminate an angular spread or angle range having a square
cross section`which extends 10 toward the right-hand side and
10 toward the left-hand side o the direction of travel. In
order to attain such an aperture angle o, respectively, 20
in vertical and in horizontal directions, the aperture angle
of a light beam axially symmetrical to the travel direction
must be at least about 28. ~ - -
In the past, one proceeded rom the assumption that thelight intensity (measured in candle power) should be as uniform
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jpossible in this light beam. If the energy available for opera-
tion of the lamp is limited, however, which is the case~ for
example, for bicycles or for parking lights of motor vehicles
¦(which also ought not to drain the battery when parking for a long
¦time), it is thus more expedient to distribute the light intensi-
ties non-uniformly following a general pattern.
This is explained by means of an example. A bicyclist travels
on a two-lane street o~ road having a width of 8 m and is located
a distance of 1 m from the side of the road. The difference in
velocity between the bicyclist and a passenger car following
behind him is generally very great) especially along straight
stretches of a road if, for example, the bicyclist i5 traveling
15 km per hour and the motor vehicle 100 km per hour~ Because
of this great velocity di~ference, the bicyclist i5 generally
overtaken more rapidly by the motor vehicle followln~ behind him
than iS a motor vehicle preceding sUch a following motor vehicle~
So that actually the rear or taillight of the bic~cle mu5t be~
vlslble better and ~arther than that oE a motor vehicle~ Since~
however, less energy is available to the bicyclist than to a motor
vehicle, the latter has been provided with a stronger i~e. more
powerful, tailight in accordance wlth the prior state of the art~
It should be taken lnto consideration that the motor vehlcle
approaching from behlnd the bicycle often travels so that the driv _
er of the motor vehicle ls located in the middle of the road. In
this case, the line of sight from the eye of the drlver of the
following motor vehicle to the tallliKht of the bicycle, wi.th
the direction of travel, lncludes an angle referred to hereinafter
as the ~viewing angle". ThiS viewing angle lncreases as the motor
vehicle overtakes the bicycle. In order for khe taillight of the
i. I
,~
bicycle to be vlsible in the respective viewing angle,
A) in an axially symmetrical aperture angle o`f the taillig~ .t
which is twice as large as the respective viewing angle,
I B) the intensity of the lighting power must be adequate
: for perceiving the light or lamp.
¦For example~ if the taillight of the bic.ycle is visible to the
¦driver o~ the approachlng motor vehicle up to a distance of 170 m
¦within a viewing angle of up to 2, the axially symmetrical
. ¦aperture angle of the light beam that remains perceivable within
this range of distance must thus be 4. In the range of distance
from 170 m to 70 m, the viewing angle is from 2 to 5, so that
the axially symmetrlcal aperture angle of the light beam visible
ln this range of distance must be from 4 to 10 . In a range of
distance from 70 m to 17 m, the viewlng angle ls from 5 ko 10, :`
so that the a~ially symmetrical aperture angle of th~ light beam :
vislble in this range of distance must be from 10 to 20.
Since the visibility of a conventional lamp decreases with the
: distance therefrom~ however, the l~ghting pawer or llght in~ensit;y
: of the beam must correspondi~gly increase from ~he out~de toward
the lnside thereof in order to ensure uniform visibility of` the
lamp or light independently of the dlstance. For example, the
range of the llght ~eam of the lamp or light~ which is visible t;o
¦ the following motor vehicle at a distance of 170 m and more9 .-.
¦¦ should shine or illumlnate more intensely than th.e rRn~e which E -:
.~ the eye of the approaching driver meets as he approaches ~ for
. example, to 17 m
.. ~aturally~ other factors are involved, such as, for example~ the
~¦ curvat~re of the road, varying road wldths, varylng travel~ng
~_3_ 3
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conditions, if on-coming or two-way traffic exists or not, and
the like. Even after taking these factors into consideration,
it remains advantageous to construct a lamp so that it, in
addition to a basic brightness which ought not to be diminished
anywhere within the light beam, additionally possesses a brightness
increasing toward the axis thereof.
In order to increase the brigh-tness sharply especially in
the viewing directions necessary for great distances, only
relatively slight amounts oE light are required, because the
closer the viewing direction is to the axis, the smaller
is the solid angle to be illuminated and the lower is the
amount of light necessary for increasing the lighting power
or light intensity.
The foregoing remarks may be summarized to the effect
that, with regard to a signal lamp, it is an object of the
invention to provide such a lap having low energy consumption,
a) which is clearly visible by other travelers on the
road even at a great distance and
b) which remains visible by these other travelers on
the road even when they approach outside or beyond the axis of
the lamp or light.
This objective is attained with a lamp such as is
described in the United States patent No. 4,143,412 issued
~arch, 6, 1979 to I~nut O. Sassmanshausen, for example, in
viewing directions which include, with the travel direction,
a viewing angle of 5, 2.5 and 1, respectively, -two, three
and five times, respectivell, the lighting power or light
intensity as in viewing directions which include a viewing angle
- of 10 with the tLavel direction. These values should obviously
not change abruptly, but rather, ~ ~
.
~ - 4 --
should continuously merge increasing]y into one another. It
has been found, however, that the basicbrightness of the lamp
ofthe above mentioned U.S. patent 4,143,412 could be improved.
With respect to the lamp ofthisU.S. patent it is an object
of the ins-tant application to provide a lamp wherein the
light in a range of 10 (viewing angle) to the axis up to
at least 15 (viewing angle) to the axis is intensified ~o
such an extent that the light distribution curve in this
range has a bulge. In this manner, the visibility of the
lamp in directions deviating from the axial direction should
be sharply increased.
According to the present invention there is provided
a lamp having a main concave andan assistant concave reflector
disposed mutually coaxially and having different parameters
and focal regions, the different focal regions being located
in the common axis of the reflectors and being spaced from
one another, the lamp comprising a light source disposed in
the focal region of the assistant reflector so that the main
reflector emlts a hollow conical light beam, and means
associated with the assistant reflector for diverting light
of the assistant reflector into a solidly conical light beam,
the solidly conical light beam of the assistant reflector
and the hollow conical light beam of the main reflector having
aperture angles corresponding to an extent that both said
hollow and solidly conical light beams exhibit at least one
of the characteristics of supplementing and overalpping one
another.
This lamp according to the invention has a light
distribution curve composed of two parts:
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a) The range of high lighting power or light intensities
located near the axis is formed of the solidly conical light
beam radiating from the assistant reflector; this range corresponds
to the light distribution curve of my aforementioned copendln~ ¦
application. `
b) The bulges on both sides of the light distribution
curve, respectively, between about 10 (viewing angle) to the
axis, are formed by the ring-shaped (hollow conical) light beam
and/or by overlapping of both light beams.
In accordance with another feature of the inventionJ the means ror
diverting the light of the assistant reflector, comprise pro-
tuberances ln t.he form of a plurali~ of at leas~ ol~e type Or
structural features selected from the group thereof consisting of
bulges and depressions formed in the reflecting surface of the
assistant reflector, all of the protuberance5 havin~ a mean height
that is 3~ to 20~ o~ a mean smallest base diame~er of all of ~he
protuberances, a maximal spacing between two points of ~he ligh~
source being at least twice as large as the mean helght of all o~
the protuberancesO
In accordance ~Jith a further feature of the inven~ion and lnstead
o~ this special construction of the reflecting surface of the
assistant reflector or in addition to khis constr~ctio~ Or ~he
reflecting surface of the ass1stant reflectorJ the means ~or
diverting the light of the assistant reflector compr~se flutes
formed in a cover plate located at a ligh~ out:Let end Or the
reflectors, the flutes being in a reg~on Or the cover p~ate
through which the light of the assiskant reflector passes.
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If the light source ls located in the focal reglon of the assistar It
reflector, a result thereof is that the main reflector emits
the ring-shaped (hollow conical) light beam which alone or
primarily produces the bulges of the light distribution curve.
Should these bulges be shifted closer to the axis of ~he lamp or ¦
should the amount of light contained in these bulges be directed
fully parallel, not only is the aforementioned possibilit~ pro~
vided advantageously, that the light source be disposed in the
focal region of the assistant reflector~ but rather, moreover,
the further possibility is afforded of shifting this light source
into the focal region of the main reflector~
In accordance with an added feature of the invention, the light
source, on the one hand, and the reflectors, on the other hand,
are adJustably shiftable in axial direction relative to one
another so that the light source is selecti~ely disposable in
either of the focal regions, the light source, when in the focal
region of the main reflector emi~ting a substantially parallel
main light beam.
, . .
A lamp with the given shiftinæ or adjusting possibili~y is suited,
for example, as bl~ilding-site lamp;. The light distri.bution is
variable so that this building-site lamp, selectlvelyJ (for
example, on straight stretches of a limited access highway) is
already v-lsible from a great distance or (for exampler on hl~h-
ways having many curves) is also visible from the side within a
given viewing angle, depending upon whether the light source is
set in the one or the other reflector ~lso, it is possible,
with such a lamp~ as desired, to shine a parallel light beam
into the distance or~ when adjusting or setting the light source !
ln the focal region of the assistant reflector, to illuminate
a great area close at hand. Thus, the lamp according to the in-
vent~on can be employed not only a5 a slgnal lamp, but also, ~or
example, as a flashlight.
I
The light-diverting means associated with the assistant re~lector,¦
should not be dulled or deadened because, when the surface there-¦
of is dulled or deadened, it would scatter the light uncontrollabl~
in all directions. In accordance with the inventionJ therefore,
a conical light beam is produced and, for this reason~ the light~
diverting means (protuberances of the reflector or flutes of the
cover plate) are formed with a smooth surface structure~ in order¦
to be able to beam the light into given angular spreads or range~ ¦
In accordance with an additional feature of the invention and~
depending upon the dispositlon of the lamp~ the aperture angle
of the light beam is between 20 and 90 and, advantageousl~,
between 30 and 60.
Especlally lf the light source ls selectlvely in the focal region
of the assistant reflector or in the focal region of the maln
reflector, in accordance with yet another feature of the inventio
the main reflector has a greater parameter than that of the
asslstant reflector so that, when setting the light source in the
main reflector, light that is as exactly parallel as possible
is produced thereby. The greater the parameter of a reflector
is in relationship to the size of the light source, the more
accurately can the light rays withln the light beam be direc~ed
in parallel.
Il - , . ..... .
In accordance with yet a further feature of the inven~ion~ the ~ -
coaxial reflectors have a light outlet opening, the main reflector
I of the two reflectors being located adjacent the light outlet
- ¦l opening. With such an arrangement, a very large par~ o~ the
` :
light rays emltted by the l~ght source can be captured. This is
especially advantageous for lamps which should illuminate) actlve-
, ly, objects or surfaces and with which, therefore~ the reflectors¦
¦ and the light source are adJustable or shiftable relative to one ¦ -
I another~ This construction is suited especially well for flash-
¦ lights and similar lamps used for illumination.
.
In order to be able to capture from the respective focal region
as much llght of the light source as possible~ especially if it
is selectively set in the one or the other focal region, and to
bring the technical expense for the shifting of the light source
down to an easily realizable value, there is providedg in accorda~ Ice
with another feature o~ the invention, that the main reflector
has a greater parameter than that of the assistant l~eflector~ the
smaller assistant-reflector parameter belng from 55~ to 80~ Or
the greater main-reflector parameter.
In accordancç with a further feature Or the invention, the maln
reflector has a greater parameter than that o~ the assistant
reflector~ the transition from the one reflector to the other
reflector is of such construction that the spaclng between both
focal reglons is 20~ to 60$, advantageously 25~ to 40%~ and
preferably 26~ to 32~ of th~ greater parameter
In accordance with an added feature of the inventlon, and to
achieve a good efficiency of the lamp, each of the focal regLons
is disposed in a surrounding space o~ the respective reflector
associated therewith. .
In accordance with an additional feature of the inventlonl and to
achieve the best possible light distribution in the various light
beams~ a plane disposed through the focal region of the main
refl ctor and perpendlcularly to the lamp axis dlvides an aDg,e
ll ~
stretching from the focal region of the main reflector to an
outer and an inner edge of the main reflector so as to form an
outer angle of at least 10, advantageously at least 18 and
preferably at least 25, and an inner angle of a~ least 5, ad-
vantageously at least 10 and preferably at least 15. With
this construction, the light beam produced by the main reflector
has a very intense light.
In accordance with yet another feature of the invention and with
regard to the assistant reflector, a plane disposed through the
focal region of the assistant reflector and perpendicularly to
the lamp axis divides an angle stretching from the focal region
of the assistant reflector to an outer and an inner edge of the
ass:lstant reflector so as to form an outer angle of at least 0~
advantageously at least 2 and preferably at least 5) and an
inner angle of at least 10, advantageously at least 18 and
preferably at least 25. With the assistant reflec~or~ it is
also advantageous if the inner angle of light acceptance through
the reflector is considerably greater than the outer one whereas,
for the main reflector, this relationship should be reversed i~
possibleO
In accordance with yet a further feature of the inventionJ an
outer edge of the assistant reflector and an inner edge of the
main reflector are closely adjacent one another.
I
In accordance wlth an alternate feature of the invention, an
outer edge of thc assistant reflector and an ~nner edg~ of l;he
maln reflector substantially coincide one with the other.
. .
The same applies, obviously~ when the reflectors are disposed
in other successions or sequences, since the outer edge of the
main reflector and the lnner edge of the assistant reflector must
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then lie as near one another as possible or must at best coincide.
In accordance with yet another feature of the invention, the
protuberances are in the form of calottes and have a height which
is 3.5% to 12~, and preferably 4~ to 8~ of the smallest base
diameter thereofJ the greatest distance between two points of the~
light source being at least twice as great as the mean height of
all the calottes.
In accordance with an alternate feature of the invention, the
protuberances are in the form of rings and have a height which
is 3.5~ to 12~, and preferably 4~ to 8~, of the width of a
respective ring, the greatest distance between two points of the
light source being at least twice as great as the mean height of
all the rings.
In accordance with yet an added feature of the invention, and
advantageous for various application, to provide means for
homogenizlng light associated with the main reflector~ Such
light-homogenizing means should not divert the light to such an
extent that it experiences a critical or decisive change in
direction, but rather, the light rays should be only very slightl~
influenced in order to intermix the respective light beam bet~er
and also to distribute the light uniformly within this llght
beam. I
If the light source is disposed in the focal point of the assista~t
reflector, one can determine that the light re~lected from the
main reflector emerges in a relativel~ narrow ring-shaped reglon
through the cover plate. It is advantageous and in accordance
with the invention to furnish this ring-shaped region in the
cover plate with the light-homogenizing means in the form, for
example, of flutes, ~hereb~ the hollow-conical light beam o~
15 1~3~`6Z
the light re~lected by the m~in reflector ls homogenl~ed. If
the light source, howeverJ is dlsposed in the focal region Fl of
the main reflector, then a great part of the parallel light
rays emerges outside of the ring-shaped region of the cover plate
which is provided with light-homogenizing means i.e. a greater
part of the light rays are not reached by these homogenizing
means in this position, whereby the sharp parallelism of the
ligh~-beam is maintained an~ only a given part is homogenized.
In accordance with yet an additional feature of the invention,
the flutes ha~e a respective cross section in the form of an
obtuse triangle havlng legs forming flanks of the respective flute
the legs including, with the surface of the cover plate~ a flank
angle of 3 to 20J and advantageously of 5 to 12.
In accordance with another feature of the lnventlon, for other
applications, the light homogenizing~ means comprise protuberances
(bulges and/or depressions) dlsposed Oll the reflect~ng surface
of the main reflector and havlng an extremely slight curvatùre
i.e. a verg large radius of curvature. Due to the extremelyslight
curvature~ the light is not diverted from the main direction
thereuf, but rather, is homog~nized somewhat only within the ll~ht
beam. The main reflector could therefor also be provided with
small facets; for example, the exact]y parabolic shape of the~
reflectors could be broken down into a multiplicity of small re- !
flecting sur~aces or areas which are somewhat tangen~ial to the
mathematically ideal surface of the paraboloid. What is common
to all of these light homogenlzing means is that they diver~ the
light only quite negligibly, The surface structure should like-
wise be quite smooth i.e. highly polished, so that as little
diffused light as possible occurs and the light beam according
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to the invention thus becomes lost.
In accordance with a further feature of the invention, a collect-
I ing lens is disposed ln axial direction of the lamp in front of
j the light source for capturing and collecting light rays emitted
from the light source and emerging directly in direction of a
light outlet opening of the lamp and superimposing the thus
¦ collected light rays on a light beam collected and united by the
main and the assistant reflectors. Such a collecting lens can be
constructed, for example, as an integral part of the co~er plat~ 5 O.
In accordance with an added feakure of the invention, the collect-
ing lens is constructed as a collecting lens of a lensend in-
candescent lamp, because thereby a considerably greater part of
the light emerging from the light source can be captured and
collected without the lens becoming so large that it disruptively
affects the light beamed by the reflectors.
In accordance wikh an added feature of the lnvent:lon~ both the
main and the assistant reflector are integral with one another.
In accordance with an additional feature o~ the invention~ the
lamp has a light intensity increasing with decreasing distance
from the lamp axis so that part of the light beam which includes~
with the lamp axis, an angle of 2~ has at least 2~1 times th~
light intensity of a part of the llght beam which includes, wit.h
the lamp axis, an ang]e of 15 . ¦ -
In accordance with an alternate feature of the ln~enti(3n, the ¦
lamp has a light intensity increasing with decreasing dlst;ance
from the lamp axis so that part of the light beam which includes, ¦
with the lamp axis, an angle of 5, has at least 1.8 times the
j light intensity of a part of the light beam which includes~ with
the lamp axis, an angle of 15. A light distribution curve is
~$ ~ I
thereby given whlch ensures that the light intensities, which hav~
a given basic brightness as seen in the range of 150 ~rom the
axis~ increase toward the axis so that travelers on the road
which approach such a lamp on a straight road at high velocity ar
already warned whlle yet at a great dlstance therefrom~
If such a lamp is used as a flashlight, such as, for example, to
illuminate the englne compartment of a bicycle during repairs,
then the greater brightness occurring in axial directlon can be ¦
diverted, for example, directly upon the trouble spot~ such as,
for example, a faulty spark plug, and nevertheless, adequate
brightness is obtalned in the surroundings Or the axial region in ::
order to percelve clearly all of the obJects presen~ in the
engine compartment. ~:
Xn accordance with a concomitant feature of the invention~ the
lamp has a light intensity increasing wlth decreasing distance
from the lamp axis so that part of the llght beam which includesJ :
with the lamp axis, an angle of 2, has at least ~our times~ the
light intensity of a part of the light beam whlch include3, with. : :
the lamp axis, an angle of 15 ~ :~
In accordance with an alternate feature of the invention, th~ lam
has a light intensity increasing with decreasing distance from
the lamp axls so that part Or the light beam wh-lch includes~ with
the lamp axis, an angle of 5 , has at least twice the light in~ ¦
tensity of a part of the light beam whlch lncludes, ~l.ith tlle lamp;
axis, an angle of 15. . I
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. I O-ther features which are conslderc~ as characteristic for the in-
I vention are set forth in the appended claims.
;Although the invention is illustrated and described herein as em-
bodied in a lamp~ it is nevertheless not intended to be limited
to the details shown, slnce various modifications and structural
changes may be made therein without departing ~rom the spirit of
the invention and within the scope and range of equivalents of the
claims.
The construction and method of operation of the invention, how-
¦everl together with addltional objects and advantages thereof wlll
¦be best understood from the following description of specificembodiments when read in connection Witrl the acco~panylng draw-
lngs, ln whlch:
FIG~ 1 is a plot diagram of a light distribution curve for an e~-
bodlment of a lamp or flashlight constructed in accordance wlth
the invention~ llght lntensities being plotted therein against the
angles thereo~ to the axis of the lamp or flashllght;
FIG. 2 is a diagrammatic longitudinal sectional view of the lamp
embodiment emitting the light of which the light distrlbution
curve is plotted in FIG~ l;
I
¦ FIGo 3 is a frag~entary enlarged view of FIG~ 2 showing a so-c~llec ~ :
lassistant or supplementary reflector below a parting or dividing :
; lline of the lamp;
FIG~ 4 is a fragmentary top plan view of FIG. 3 show:Ln~ one of the¦
curved surface portions of the assistant refleGtor,
~ i . `I
¦ FIG~ 5 is a cross-sectional view of FIG~ 4 taken along the smalles
: I bas; dlameter B thereof;
',~ I .
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IFIG. 6 :ls an enlarged fragmentary view of FIG. 2 showlng the coile~
,luminous body thereof as constructed in accordance wlth the in-
vention; :.
IFIG. 7 is a view simllar to that of FIG. 6 Or another embodimentlor the luminous body; -
FIG. 8 is a vlew similar to that of FIG. 2 showlng another embodi-
ment of the lamp according to the invention; ~:
FIGS. 8 and 8b are enlarged f`ragmentary views of FIG. 2 show~ngIdifferent embodiments of the lamp cover plate thereof formed wlth
¦circular flutes having truncated triangular and round or parabolic
cross sections~ respectively;
FIG. 9 ls a view similar to those o~ FIGS. 2 and 8 showin~ yet : ~:
another embodiment of the lamp accordlng to the invention;
FIG. 10 is a fragmentary view of` FIGS. 2 and 9 showing the reflec-
tor structure of the lamp in somewhat g:re~ter detail;
IFIG. 11 19 a view similar to that of FIG. 10 of another embodiment :
1f the la~p reflector structure;
FIG. 12 is a view similar to those Or FIG~ 2~ 9 and 10 ~howing ~he
lamp reflector structure together witll a cove~ plate cons~ruc~ed
in accordance with the invention;
, FIG . 12a is an enlarged f`ragmentar~ vlew of FIG O 12 show:Ln~ the
¦l~f'lute formation in a part of the covcr plate in clearer detall;
~IFIG~ 13 is a view similar to that of FIU. 10 sho~ing yet another
I!embodlment of the lamp reflector structure;
FIG . 14 is a view similar to those of FIGS. 2 and 9 showing a lamp
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with a reflector structure and cover plate sirn:Llar to those ofFIG. 12; and
FIG. 15 is a view similar to that of FIG. 12 of yet a further
different embodiment of the reflector structure.
,Referring now to the drawing and first~ partlcularly to FIG. 1
,thereofJ there is shown a lirrht distribution curve 74 of light
intensities 72 shown in dependence upon the angle thereof to the
axis 12 of the lamp according to the inventlon, an embodiment of
¦which is illustrated in FIG. 2, As shown in the plot diagram of
¦FIG. 1, the lamp is represented to be at the point and radiates
¦light in direction of the axis 12 thereof,correspondin~ to 0~ on
th~ abscissa of' the illustrated coordinate system. This light dis
tribution curve 7L~ ~Yas plotted for the light source 60 located ln
! the focal region F2 of FIG. 2, A bulging of the light lnten3itie~
72 ls formed in the light distribution curve 74 at the region3 76,
this bulging belng produced by the light beam 14 of the main re-
~lector 10 and affording good illumination of the marginal zones
of the combined conical llght beam 14, 16~ If the lam~ accdrding
to the invention i3 used as a signal lamp9 the bulge in the light
linten3ities 72 at the region~ ~6 ~hus formed by the annular light
¦beam 14 considerably improves lateral visibility of such a signal
lamp.
¦FIG. 2J as aforementloned, shows the larnp which emits tle ligh~ ln
accordance with the llght distrlbutlon curve 7l~ of FIG, 1. The
luminous body 60 of the incandescent lamp 61 is located ln ~he
¦focal region F2 o~ an assistant or sup~lementary reflector 30~
Llght rays emanatlng from the luminous body 60 and fallin~ on the
reflecting surface of the assistant reflector 30 are collected by
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the latter, with the aid of protuberances 42 ~ormed in the reflec-l
ting surface thereo~J into a conlcal beam having an aperture angle ¦
~21. The light within this conical beam 16 hav~ng the aperture
langl~ Is advantageously distributed so that the li~ht inten-
,sity of this beam 16 increases from the marginal regions to the
axis 12 th~reof. The main reflector 10 of the lamp or flashlight
simultaneously emits and annular hollow conical beam 14 having an
aperture angle ~ 2 when the light source 60 is disposed in the
focal region F2.
I . I
The conical beam 16 of the assistant re~lector 30 should illuminate
the dark middle zone of the annular hollow conical light. beam 14
of the main reflector 10. Vlewed outwardly from the axls 12~ ther~
is first the light beam 16 to which the annular conical light beam
14 can be seamles31y conn~cted. The lamp according ta the inven-
tion can also be constructed so that the marginal zones of the
conlcal light bea~ 16 overlap the annular hollow conlcal llght
beam 14. Since the light beams 14 and 16, ln an~ event~ hawever~
derive from various diameter regions of the hollow rerlectlng
mirrors 10 and 30, a certain overlapping ef~ect~ depen~ing upon
the distance of the illuminate~ surface or o~ect there~rom~ wlll
aLways occur anyway.
¦The lamp has a light aperture 22, the main reflectof 10 has a ¦
~ocal region Fl, and the ass:lstant or supplementary reflector 30
borders on the main reflector 10 along a separating pla~e T. An
incandescent lamp 61 is sho;~n screwed lnto a l--mp holder or so~et~
66 in FIG. 2 and proJects throu~rh a central openin~, 31 ln~o ~h~ ! :
¦,lamp. The lamp has a central axls 12J and is provlded with a
~cover plate 50 in ~ront Or the llght aperture 22r :
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¦~ FIGo 3 shows part of a lam~ constructed in accordance ~ith th~
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c~
I:Invention, n~mely the p~rt with the assistant re~lector 30 located¦
¦below the separating plane TJ ~ seen in the figure. To provide
la better understanding of the constructlon of the lamp according
¦to the lnvention~ one of the protnberances 42 is sho~n ln enlarge-
ment in ~IG. 3, and the smallest base diameter B and the height h
las ~lell as the curvature radius r thereof are also indicated. The
light source 60 is disposed in the focal region F2 o~ the assistan
or supplementary reflector 30. The center of the focal region F2
of the as~lstant reflector 30 ls spaced a distance S from the
apex 33 of the parabolic asslstant reflector 30. The incandescent
lamp shown in FIG~ 3 has a flange base or cap 59. .
FIGo 4 illustrates one of the probuberances 42 in a ~reatly en -
larged View, the smallest ba5e diameter B the~reof being readily
apparent.
In FIG. 5 there is shown a cross-sEctiona.l vlew of the pro-
tuberar~ce 42 of FIG. 4 taken along the smallest base.diameter B
thereof. The original parabolic surface 48 Of the assistant
reflector 30 iS indicated in FIG. 5. The protuberance ~2 rl~e~
to a height h above the smalle~t ba8e diameter B thereo~ Th~
radius of curvature r of the protuberance 42 ls also lndicated
in FI~. 5~
The assistant reflectors 30 are advantageously construct.ed 30
that the parabolic reflecting surfacc thereof i~ provi.de~ ~ith
, protuberances 42 (~ulges and/or depre~ions)~ the mean height h
' of all of the protuberances 42.being from 3/ to 20~ advantageous~¦
¦ ly from 3 . 5~o to 12~o and preferably from 4~o to ~ o~ the mean
smallest base diameter B of all of the protuberances 42~ and the
greates-t spacing between two points of the light source being at
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least twice as large, advantageously at least three times as
large and preferably at least five times as large as the mean
height h of all of the protuberances 42. Through the cooperation
of a luminous body of defined dimensions with the protuberances
42, the dimensions of which have the foregoing relationship with
the dimenslons of the luminous body, a conical light beam i~
formed whlch, to an observer, increases in light intensity
from the margin thereof toward the axis thereof.
The protuberance 42 shown in FIGS. 4 and 5 is not round. It -
could, however, also be round, just as well. In the cases wherein
protuberances 41 (FIG. 15) are provided in the form of rings
around the hollow mirror axis 12, the smallest diameter B of
the respective protuberance 41 is equal to th~ ~ridth of the
respective ring. If calculations are made with the mean values
of the height h and the smalles base diameter B of all o~ the
protuberances 42~ this then confines the possibility of lndividual
sharp deviations from these mean values. The smaller the
deviation~ from the mean values, the better i~ the light
distr~bution that is attained
. . :. '
The be~t re9ult~ are obtained if the height h substantially of
each individual protuberance is from 3% to 20~ advantageously ¦
3.5% to 12~o and preferably 4~ to 8% of the smallest base
diameter B thereo~. It is further~nore advantageouE 1~ the
greatest extension of the projection of the luminous body on
a plane perpendicular to the directlon of the greateEt extension i
thereof is at least 25% of the mean height ~l of all Or the
protuberances 42 or rings 41, and advantageously of the height h ¦
of each individual protuberance 41 or 42~ ~n eEpecially ~avorable
light distribution~ for an observer, in all lines of sight or
I viewing directions(lying in the illuminated aperture angle) is
produced if the ~ean smallest base diameter B of all the
protuberances 42, and advantageou~l~y the smallest base diameter
j B of each individual protuberance is 5% to 40~, advantageously
i 7~ to 30~ and preferably 9~ to 25~ of the spacing of the apex
of the parabolic hollow mirror reflector from the focal point
thereof or from ~he middle of the focal region thereof~
Good results are attained lf the surfaces of the protuberanceq 42
are formed as spherical calottes advantageously having a radiu~
of curvature r between 10~ and 70~ preferably between 15% and
50~, of the spacing of the middle of the focal region from the
apex of the assistant reflector 30. In FIGS. 2, 3~ 9, 10, 11, 12,
13, 14 and 15, the assistant concave reflector 30 is generally
parabolic i~ the small deviations due to the protuberances are
ignored
To control the light distribution, it can be-advantageous if the
surfaces of th~ protuberances are cutaw~y portions or sections
of elllpsoids or ellipsoidal surfaces, and the plan vlew Or the
base of the protuberances is elongated, advantageously elliptical
or nearly or somewhat illiptical.
In an advantageous embodiment, as aforernentionedg the pro-
~uberances can be constructed in th~ form of rings coaxlally or
concentrically surrounding the axis o~ the hollow mlxror reflector
the surfaces of the rings being advantageously cutaway portions
or sections of toroidal surfaces. Also as noted hereinafter~ the
smallest base diameter of a re~pective ring-shaped protuberance lil
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corresponds to the width o~ one of the rings. Such r1ng-shapeù
protuberances are shown in FIG. 15.
The surface structure of the protuberances 42 should be as smooth
as possible, because no diffused light but rather a conical light
beam with quite specific aperture angles is supposed to be
produced O
FIG. 6 shows a coiled luminous body of an incande~cen~ lamp~ The
greatest distance between two points of this luminous body is
indicated by the measurement b. This greatest spaci.ng b between
two points of the light source should be at least twice a~ large
as the mean height h of all of the protuberances 41 or 42~
FIG. 7 shows a di~ferently shaped luminous body than ~hat ln
FIG. 6. Also in FIG. 7, the greatest distance between two polnts
of the luminous body 2 is indicated by the mea~urement b. In
FIG. 7, as well, the greatest spacing between two points of the
lumlnous body should be at least twice as large a~ the mear
height h of all of the protùberances 41 or l~2~
FIG~ 8 shows a lamp similar to that in FIG. 2 with the difference,
however, that both the main concave reflector 10 and the asslstant
concave re~lector 30 have a reflecting surface ~hat -Is formed
without any bulges and/or depresslons. For that reason, light.-
bending or diverting means are provided in a ring-s~laped regior, 5l~
of the cover plate 50 which 15 impin~;e~ upon by par~311el--direc~ec3
light rays from the assistant reflector 30, so a.s to ~ivert the
axial parallelism of these llght rays into a conical li~ht beam
with an aperture angle of, for example 40~, in order to suppl.e-
ment, radially inwardly3 the ring-shaped conical light beam 14 :
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produced by the rnain reflector 10 or, if de~ired, also to overlap
the light beam 14. In the ca~e at hand, the light-diverting or
bending means, which are located in the region 54~ are made up of
flutes incised or ~ormed in the cover plate 50 and encircllng the
axis 12, the flutes having flanks 32 that are so inclined as to
break the light into the desired aperture angle~
If it is desired to receive specially great light intensities in
axial direction, the bottoms or the points of these flutes can be
made plano parallel so that the light does not experience any
~hange in directlon thereat. This is shown in FIGo 8a. FIG. 8b
shows a different type of the flutes 36 having a round or,pre~
ferably, also a parabolic cross section in order thu~ to ~orm
the light di~tributlon homogeneously within the light beam 16.
Naturally, other light-diverting means, such as circulal ring-
shaped lenses, for example~ can also be used ~or diverting or
bending the light into the desired aperture angle in the region 54
FIG. 9 shows the same lamp as in FIG. 2 with the dif~erence~ how-
ever, that the main reflector 10 and the auxiliary rerlector 30
ha~e been so shifted with respect to the light source 60 in
directlon of the lamp axis 12 that the light sour~e 60 is no
longer loca.ted in the focal region F] of the mai.n reflector 10.
In this location of the llght source, a narrow~ substantially
parallel light beam 13 is produced by the smooth reflecting
surface of the main re~lector 10. The reflecking surfa~e of the
main reflector 10 could also be equipped with very s~ighk bulges
and/or depressions for homogenizing the substantially parallel
bright light beam. The main reflector 10 terminates at the p~ane Tl
àt which it borders on or abuts the asslstant reflector 30 .
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having -the focal region F2. Advantageously, both hollow mirror
reflectors 10 and 30 are formed of one piece. Both hollow mirror
reflectors 10 and 30 have the same lamp axis 12. In vicinity of
the apex of the assistant reflector 30 is an opening 31 through
which the light source~ such as the luminous body of an
incandescent lamp, for example, projects into the reflectors 30
and 10.
The holder or mounting support for the hollow mirror reflectors
30 and 10, on the one hand, and the light source 603 on the other
hand, should be so cons~ructed that the light source 60 and the
reflectors 30 and 10 can be shifted or adjusted relative to one
another in axlal direction so that the light source 60 can be
brought selectively into the focal region Fl or into the focal
region F2. In FIG. 9, the light source 60 of the incandescent
lamp 61 is located in the focal region Fl o~ the main reflector 10
which emits tne parallel li~ht beam 13 in this settlng. In
prac~ice, not all of the light rays are exactl~ parallel because
the luminous body 60 of the incandescent lamp 61 is not ideally
punctiform and also the reflector 10 can obviousl~ be produced
only nearly but not mathematically exactly~ Due to these sli.ght
deviatlonsS the light beam 13 is~ indeed~ sub~tantially parallel
at a given short distance from and in~ront of ~he lamp yet~
however~ is already so well interrl~ixed that it appcars to the
viewer as a closed parallel light ~eam~
FIG~ 10 shows an embodi.ment of a :l..amp according to the inven-tion
which is simiLar to that of FIGS. 2 and 9, but which has been
provided additionally for explaining the angle of light
acceptance, A plane SFl perpendicular to the axis 12 is disposed
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through the focal region Fl of the maln reflector 10. This
plane SFl and a straight line 28 intersecting therewith and
passing through the focal region Fl and through the outer edge 23
of the main reflector 10 include an angle a of about 31. Further- :~
more, this plane SFl, with a straight line 29, which extends :
through the focal region Fl and the inner edge 26 of the main
reflector 10, includes an angle ~1 of about 21. Altogetherg : :
light beams emitted from the focal region Fl are held by the
main reflector 10 within the range of an angle al + ~1 = 52~
A plane SF2 perpendicular to the axi~ 12 is disposed through
the focal region F2. This plane SF2, with a stralght line 20
which extends through the focal region F2 and the outer edge 26 -:
of the assistant reflector 30 includes an angle a2 of about 5.
The light-acceptance angle of the assistant reflector 30 is
limited by a straight line 21 below the plane SF2~ a3 viewed in . .
FIG. 10, the straight linè 21 extending through the inner edge 18
of the assistant reflector 30 at the inlet opening 31 for the
incandes.cent lamp. The angle ~2 bekween the plane SF2 and th~
straight line 21 is about 33 in the case at han~r Altogethel,
if the light source is located in the focal region F2~ light is
thus held by the as~istant re~lector 30 in an angle range ~.? ~- ~2
= 38. The spacing of both focal regions Fl and F2 f`rom one an-
other is about 30~0 of the parameter of the main reflector 10.
The parameter of a parabola is t~ice as large as the spacing of
the focal point of the parabola rrom the apex of the parabola~
The focal region Fl is surrounded by the maln reflector 10$ and
the focal region F2 by the a~sistant re~lector 30~ The parameter
of the assistant re~lector 30 i9, in this case, 68% o~ the
parameter of the maln ref`lector 10.
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FIG. 11 shows a hollow mi.rror reflector having a main reflector 10
with a greater pararneter than that of the assistant reflector 30
thereof. The focal region of the main reflector 10 is located .. .
at Fl, whereas the focal region of the assistant reflector 30
is at F2~ If the light source is disposed in the focal region Fl,
the main reflector 10 then emits nearly parallel light. I~ the
light source is then brought into the focal region F2 of the
assistant reflector 30, the hollow mirror reflector 10 then
produce~c a ring~shaped conical light beam which is illuminated
in the inner region thereof by a conical light beam of the
assistant reflector 30. This conical ligh~ beam brightens or .
illuminates the aperture angle thereof due to the protuberances 42
provided on the surface of the assistant reflector 30~
In the embodiment of the invention shown ~n FIG. 11, the main
reflector 10 could naturally~ also be extended to the light
outlet openlng 22, as presently illustrated in the ~lgure~ and
the assistant reflector 30 with the protuberanceq 42 thereor
could then be disposed beyond or forwa~d of khe presently sho~l
light outlet opening 22 located at the end of the thus elongated
main reflector 10. .
FIG. 12 shows an embodiment of a lamp similar to ~hat shown in
FIGS. 2, 9 and 10. If the light source is brought toward the
~ocal region F2, a surprising observation is made tha~ most o~
the llght ra~ys that are collected by the main reflector 10
emerge through a relatively narrow rlng shaped region 52 of ~he
cover plate 50. In order to homogenizb somewhat ~his narrow
ring-shaped region of the hollow conical light beam 1ll~ ring~ I
shaped flutes encircling the axis 12 are provlded in the cover .
_25- ..
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plate 50 at the region 52. In FIG. 12a, such ~lutes 53 are shown
in an enlarged view for a better understanding of the con-
¦ s-truction -thereof. It has been found to be sufficient if these
flutes 53 form with the flanks 55 and 56 thereof an angle of
¦only 3 to 20, and prefer~bly of 5 to 12~, with the plane of
¦the cover plate 50. Advantageously, these or other light
distributing means are provided in this region 52 at the inner
side of the cover plate 50 so that they do not become filled
with dust. If the light source is then brought toward to focal
point Fl o~ the main reflector lO, the parallelism of the light
beam then becomes impaired somewhat ~homogenized) onl~ in the
small ring~haped region of thc ~lutes at 52~ wherea~ the li~ht
ray~ in the entire remaining region of the cover pla~e 50 can
emerge undisturbed in parall~l~ Through the small region 52
provided wl~l only limited li~g~lt-distributlng means, only a
given homogenization of a small part of the parallel rays occurs
in the bright light beam, which has barely an~ negative e~ect
. upon the range of the parallel light beam yet give~ the light
beam a greater unlformity.
FIG. 13 shows a lamp ~imilar to the lamps shown in ~IGS. 2, 9
and 10~ yet with the difference thatg in FIGr 13~ the main
reflector 10 i~ provided with quite weakl~ punched ou~ or embossed
bulges and/or depressions, such as protuberances 435 for example~
These do not have the function of dîstributing the light over
a large angle range, but rather, because of the very weak op~ical
efficiency thereof, serve on:Ly for homogenizing the parallel ligh~
Ibeam when the light source is set in the ~ocal region Fl.
I ¦Obviously, if the light source is brought toward the focal region
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F2, the ring-shaped hollow conical li~ht beam 14, which then
emerges from the main reflector 10, is thereby also homogenized.
FIG. 14 illustrates an embodiment of a lamp according to the
invention whlch is sim`ilar to the embodiment in FIG. 12. A
collecting or condenser lens 62 is disposed, in this case, in
~ront of the light source 60. If the light source 60 of the
lensed incandescent lamp 64 is set in the ~ocal region F2 of the
assistant reflector 30, the main reflector 10 then deliveres a
light ring which is filled out by the conlcal light bearn that
is collected by the assistant reflector 30 and fanned out due
to the light-distributing protuberances 42. The light rays~ which
would otherwise emerge ineffectually, without beaming, through
the light outlet opening 22 of the main reflector 10~ are thus
rormed into a beam by the collecting lens 62 and overlaps both
light beams thrown by the hollow mirror re~lectors,10 and 30~ An
especlally good homogenization and reinforcement of the illumi-
nation in these combined lig-ht beams is thereb~ attained. The
socket or receptacle 66 into which the lensed incandescent
lamp 64 is screwed, tapers or narrows down in a part ~8 thereof
so that the assistant reflector 30 can slide with the openi~g 31
thereof over this socket part 68~ when the light source 60 ~s
shifted into the focal region Fl, if the main reflector 10 ls
supposed to produce a parallel light beam.
FIG. 15 shows a lamp similar to that in FIG~ 12 but whereln the
assist~nt reflector is ~urnished~ however~ with protuberante
rings 41 running around the axis 12 instead of with dome and or
cup-shaped protuberances 42. ;~
