Note: Descriptions are shown in the official language in which they were submitted.
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D-84-1-159 -1- PATENT
TITLE: MOTOR VEHICLE HEADLIGHT
TECHNICAL FIELD
~he present invention relates to headlights for use in
motor vehicles (e.g., automobiles).
CROSS REFERENCE TO COPENDING APPLICATIONS
In U.S. Patent 4,545,001, entitled "Sealed Lens Member
For Use In A Motor Vehicle Lighting System" (Inventors: ~. J.
English et al), there is defined a hollow, single piece lens
member for use in a motor vehicle lighting system containing
a plurality of individual lighting modules.
In U.S. Patent 4,646,207, entitled "Motor Vehicle
Lighting System Including A Sealed Lens Member As Part
Thereof" (Inventors: R. E. Levin et al), there is defined a
motor vehicle lighting system including a light source and
reflector means, a hollow, enclosed lens having a contoured
front surface with a rear lensing surface, and a means for
mounting the lens in a recess of said vehicle to assure
adequate passage of light from the source through the lens.
In U.S. Patent D285,351, entitled "Lamp-Reflector Module
For Use In A Motor Vehicle Headlighting System" (Inventors:
G. J. English et al), there is claimed the ornamental design
for a lamp-reflector module for use in a motor vehicle
lighting system.
In U.S. Patent D284,112, entitled "Lens Member For A
Motor Vehicle Headlighting System" (Inventors: G. J. English
et al), there is claimed the ornamental design for a motor
vehicle headlight lens member having a plurality of stepped
lensing surfaces thereon and a slightly curved forward
surface.
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D-84-1-159 -2- PATENT
In U.S. Patent D283,362, entitled "Lens Component For A
Motor Vehicle Headlighting System" (Inventors: R. E. Levin et
al), there is claimed the ornamental design for a motor
vehicle headlight lens having a sloped, clear front surface,
a pair of side walls, a bottom wall, and a stepped, rear
lensing portion to in turn define a sealed, single piece
component.
In U.S. Patent 4,569,002, entitled "Motor Vehicle
Lighting System" (Inventors: G. J. English et al), there is
defined a motor vehicle lighting system wherein each of the
lighting modules includes a clear cover. The array of
modules (e.g., four per side) is designed for use with a
spaced, common lens component located a distance from the
''' modul~s.. ~
In Canadian Patent Application 478,615-7, filed April 9,
1985, entitled "Lighting Module For Motor Vehicle Lighting
System" (Inventors: G. J. English et al), there is defined a
lighting module for use as a part of a vehicle headlighting
system wherein the module includes a reflector, a small
tungsten halogen capsule sealed within the reflector, and a
clear, front cover providing a seal for the module.
All of the above-identified U.S. Patent Applications were
filed April 10, 1984, are assigned to the same assignee as
the instant invention, and were sub~ect to an obligation to
assign to said assignee or were so assigned at the time the
instant invention was made.
BACKGROUND
Previous headlights as typically utilized in automobile
headlighting systems have heretofore been relatively large in
total frontal area. One factor which contributed
significantly to this requirement was the overall vertical
height of such headlights. As will be illustrated below,
such headlights,
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D--84--1-159 -3- PATENT
whether of round or rectangular configuration, typically
required a minimal height of at least four inches. In view
of this requirement, the motor vehicle designed to
accommodate such headlights in turn was required to possess a
relatively large frontal area to serve as a housing for
same. As a result, the vehicle exhibited relatively high
aerodynamic drag which, as is known, constitutes the
principal cause of energy consumption at normal highway
speeds. Reducing the drag coefficient in such a motor
vehicle in turn results in improved vehicle fuel
consumption. The table below represents respective
dimensional constraints for many previous headlight systems.
TABLE
Approx.
Approx. Total System
Headlight Height area
Type (Inches) (Sq. Inches)
Sealed Beam Headlights
2 Lamp, Round 2D 7 77
4 Lamp, RoundIC/2C 5 3/4 102
2 Lamp, Rectangular 2B 5 1/4 79
4 Lamp, Rectangular lA/2A 4 1/4 111
Replaceable Capsule 2E 4 1/4 55
In the motor vehicle headlighting systems described and
illustrated in the aforementioned copending Applications,
particularly in U.S. Patent 4,569,002 and Canadian Patent
Application 478,615-7, there is defined a headlighting system
which utilizes a plurality of individual lighting modules
~headlights) which each possess a relatively short overall
height (e.g., two inches). Accordingly, a motor vehicle
utilizing such a system can in turn possess a relatively
lower front portion to in turn assure improved aerodynamic
characteristics.
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D-84-1-159 -4- PATENT
A6 vill be defined herein, the headlight of the instant
invention al~o possesses a relatively short vertical height and
i6 thu6 able to assure improved motor vehicle aerodynamics when
utilized in ~uch a vehicle. As will be defined, the headlight
of the in6tant invention i~ able to provide enhanced forward
output using a reflector having a relatively small fcontal area
and an internal light source (coiled filament) having a
predetermined length to diameter ratio. The invention i~ ~hu6
adapted for use in a headlighting ~y6tem pos6essing additional,
similar component6, or, alternatively, as part of the
headlighting systems defined in the aforementioned copending
applications.
It is believed that such a headlight (and a sy~tem
utilizing same) would constitute a significant advancement in
the art.
DISCLOSURE OF THE INVENTION
It is. therefore, a primary object of the instant invention
to enhance the motor vehicle headlight art by providing a
headlight which possesses a relatively ~mall frontal area and
yet which assures enhanced forward illumination for the vehicle
utilizing same.
It is another ob~ect of the instant invention to provide
~uch a headlight which can be ea~ily utilized with other
heaalights as part of an overall headlighting system for a
motor vehicle wherein the total frontal area required in the
vehic~e to accommodate such a system is substantially reduced.
It is a still further object of the invention to provide a
new headlight which can be produced in an expedient and facile
manner.
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D-84-1-159 -5- PATENT
In accordance with one a~pect of the invention, there i6
provided a motor vehicle headlight comprising a reflector
having a concave reflecting portion of sub~tantially parabolic
configuration defining a forward opening, the reflector having
a relatively short focal length, a cover secured to the
reflector for providing a cover for the opening, and a lighting
capsule located within the reflector and including an envelope
~ortlon having a coiled filament positioned therein and having
a sub6tantially cylindrical configuration. The cap6ule i8
located within the réflector 6uch that the envelope portion is
po~itioned within and 6ub6tantially surrounded by the concave
reflecting portion and the coiled filament is 6ub6tantially
centered at the focal point of the reflector. The coiled
filament po6se6ses a length to diameter ratio of les6 than
about 2:1.
BRIEP DESCRIPTION OF THE DRAWINGS
PIG. 1 i6 a 6ide elevational view, partly in 6ection, of a
~otor vehicle headlight in accordance with a prefecred
embodiment of the invention:
PIG. 2 i6 an enlarged, partial view of one example of a
coiled filament 6tructure for u6e in the headlight depicted in
PIG l;
. PIG. 3 i~ an enlarged, partial view of the reflector and
lighting capsule component6 of the headlight of FIG. 1,
illu6tcating the focal length and focal point of the reflector
and the relative po6ition of the coiled filament thereto;
PIC. 4 reprQsent6 a chart illu6trating the relative light
~ output ~between 0- and - 4.25 with re6pect to horizontal) in
:~ comp~ri~on to the ratio of coil length to diameter for a coiled
. 30 ril~mont ~ u6ed in the in6tant invention: and
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D-84-1-159 -6- PATENT
FIG. 5 represents a preferred embodiment of a coiled-coil
filament structure for use in the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
For a better understanding of the present invention,
together with other and further objects, advantages and
capabilities thereof, reference is made to the following
disclosure and appended claims in connection with the
above-described drawings.
With attention to the drawings, and particularly FIG. 1,
there is shown a motor vehicle headlight 10 in accordance
with a preferred embodiment of the invention. Headlight 10
includes a reflector 11 having a concave reflecting portion
13 of substantially parabolic configuration. Portion 13 is
internally coated with a reflective coating material 15
(e.g., aluminum). Coating 15 is shown in FIG. 3. Concave
reflecting portion 13 defines a forward opening 16, which,
similar to the modules described in the aforementioned
20 copending applications U.S. Patent 4,569,002 and Canadian
Patent Application 478,615-7, is of rectangular
configuration. Another example of a motor vehicle headlight
having an opening of substantially rectangular configuration
is shown and described in U.S. Patent 4,545,001.
Reflector 11 further includes a projecting neck portion
17 which extends from the rear, apex part of the reflector
and which includes a relatively large aperture (recessed
portion) 19 therein. Closure for neck portion 27 is provided
by a rear wall 21 which may be secured to or which may form
part of neck 17. Reflector 11 is a glass-filled
thermoplastic, preferably one sold under the product name
"Ryton" by Philips Petroleum, Inc., Bartlesville, Oklahoma.
An alternative plastic suitable for the reflector is a
mineral-filled nylon.
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D-1~4-1-159 -7- PATENT
Secured to the front of reflector 11 and providing a cover
for the forward opening thereof i6 a cover member 23. Cover
23, a6 illu6trated, i6 of planar configuration, 6imilar to the
forward openin~ 16 defined by reflector 11. In a preferred
embodiment cov~r 23 serve6 a6 a len~ member and thus include6 a
plurality of lensing element6 25 located on an internal 6urface
thereof facing the invention~s lighting cap6ule 27. The6e
len6ing elem~nt6 are acranged in a pcedetermined pattern to
proviae either the high or low beam functions for
headlight 10. Cover 23 i6 preferably of gla66 material but
alternatively may be of pla6tic (e.g., a polycarbonate). If
gla6s, cover 23 i6 secured to reflector 11 u6ing a 6uitable
adhesive known in the art. If of pla6tic, cover 23 may be
6imilarly attached or 6ecured to the reflector u6ing an
alternative mean6 6uch a6 ultrasonic welding. A6 yet another
alternative embodiment, cover 23 may be clear (tran6parent and
devoid of len6ing element6) 6hould headlight 10 be utilized
with a separate lensing member located immediately in front of
cover 23. One example of such a len6ing member i6 de6cribed
and illustrated in the aforementioned U.S. patent 4,545,001.
Prererably, however, cover 23 ~erve6 a6 a len6 number in the
manner depicted in PIG. 1.
~ A6 stated, headlight 10 further include6 a lighting cap~ule
;~ 27 ~hich 6erve6 a6 the invention'6 light source. A6 6hown in
~5 FIG. 1, cap6ule 27 i~ located within reflector 11 and include6
an nvelope portion 29 having therein a coiled filament 31.
Under6tandably, filament 31 provide6 the light 60u~ce for
headlight 10 upon electrical energization thereof. Capsule 27
is preferably a tung6ten halogen cap6ule wherein filament 31 i6
of tungsten material and the sealed envelope 29 include6 a
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D-84-1-159 -8- PATENT
halogen gas therein. The halogen cycle is known in the
lighting field and further explanation is thus not deemed
necessary. One example of a tungsten halogen lamp is
described in U.S. Patent 4,262,229. As further shown in FIG.
1, capsule 27 also includes a press sealed end portion 35
located adjacent the hollow envelope 29 and in which is
positioned a pair of lead-in conductors 37 which are
electrically coupled to filament 31. The preferred material
for capsule 27 is glass (e.g., quartz) while that for the
lead-in conductors is preferably nickel or molybdenum.
Conductors 37 are sealed within end 35 during formation
thereof and may include an interconnecting molybdenum foil 39
as part thereof. Use of such a foil in tungsten halogen
lamps as known. Understandably, each lead-in conductor
provides a path for electrical current when coupled to an
appropriate external connector or the like which forms part
of the motor vehicle's electrical system. Each of the
externally projecting ends of conductors 37 is rigid in
construction and is firmly positioned and passes through the
electrically insulative back wall 21 of reflector 11. This
securement may be accomplished by ultrasonic welding or,
alternatively, using a suitable adhesive. In either event,
this form of retention serves to positively orient capsule 27
in the position depicted without the need for additional
clamping member or the like about press sealed end 35.
In accordance with the teachings herein, capsule 27 is
positioned within reflector 11 such that envelope portion 29
is located within and substantially surrounded by the
parabolic, concave reflecting portion 13. In addition,
coiled filament 31 is substantially centered at the focal
point FP (FIG. 3) of the reflector. Further, in accordance
with the teachings of the
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D-84-1-159 -9- PATENT
in6tant invention, coiled filament 31 iB of sub~tantially
cylindrical configuration (FIG . 2 ) and po6se~ses a length to
diameter (width) ratio of le66 than 2 :1. The length dimen6ion
i6 repre6ented by the letter L in PIG. 2 while the diameter (or
wiath) aimen6ion is depicted by the letter H in FIG. 2.
Purther, the length L of the coil must be 6mall in
compari60n to the focal length PL of the nominally parabolic
re~lector. Thi~ reguirement is necessary to a6sure that the
bundle of rays reflected at each point on the reflective
~urface will have sufriciently 6mall aivergence 6uch that 6aid
rerlected light i6 efficiently utilized in the u6ual automotive
headlamp light di6tribution pattern; that i6, a di6tribution
with greater angular divergence horizontally than vertically.
Por the 6mall aperture, 6hort focal length reflector de6cribed
horein, the filament po66e66es a length that doe6 not exceed
approximately 30 percent of the reflector focal length.
Utilization of a filament 6tructure po66e66ing the above
dimen6ional requirement6 in combination with a parabolic
-; reflector having a relatively 6hort focal length (FL in PIG. 3)
ha~ re6ulted in a headlight po66e66ing enhanced forward liqht
output. Specifically, u~e of 6uch a reflector enable6 greater
flux collection efficiency for the light emitted from filament
31. In addition, utilization of a filament having the
de~cribod length to diameter ratio insures that elemental beam
6prea~ leaving sUCh a reflector is never much greater in ~he
vertical direction than in the horizontal direction. Exce66ive
vertical 6pread represents wasted light from 6uch a headlight
becau~e the reguired vertical 6preaa i6 6ignificantly le66 than
the corre6ponding horizontal reguirement. In other term6, the
forwar~ pro~ected light from each elemental beam contributes
greater to the de~irea forward, 6ub~tantially horizontal
patt~rn if it~ ~pread in both the vertical and horizontal
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D-84-1-159 -lo- PATENT
direction6 i8 sub6tantially the same. Excessive vertical
spread by ~uch a beam al60 increase~ the amount of glare from a
headlight.
~oiled filament 31, which may also be of coiled-coil
configuration (FIG. 5), is preferably located axially alonq the
reflector's optical axis OA-OA (FIG. 3). Alternatively,
filament 31 may lie orthogonal to the optical axis provided it
i~ of course centered at focal 2oint PP.
A~ stated, the reflector of the invention posses6es a
relatively short focal length. As further stated, this results
in a reflector possessing increasing optical efficiency. In
most prior rectangular shaped headlamps wherein the forward
opening is rectangular as is that of the instant invention,
such as illustrated in U.S. Patent 4,210,841, the parabolic
upper and lower reflecting surfaces are r0stricted by
substantially horizontal planes to thus deprive the reflector
of much of its parabolic reflecting regions. As a re~ult, flux
incident on the6e horizontal planes is lost from the principal
beam of the headlight. Utilization of a shorter focal length
and minimal horizontal surface~ reduces the 601id angle of flux
interception by these planar areas for a given forward open
area of rectangular configuration. As shown in FIG. 1,
reflector 11 utilizes minimal cut-off to the parabolic
; reflecting surfaces thereof while still maintaining the
aforementioned extremely small vertical height (about two
inches or less). In accordance with the teachings of the
instant invention, reflector 11 possessed a focal length within
the range of from about 0.2 inch to about 0.5 inch. Such a
length is clearly extremely small, particularly when
considering that reguired in the headlights utilized in the
systQms listed in the aforementioned TABLE. Typically, such
h~lights roguire a focal length in the range of from 1.0 to
1.5 inches.
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D-84-1-159 -11- PATENT
A6 ~tated, the overall vertical height (H in FIG. 1) for
headlight 10 is very 6mall. In accordance of the teachings
herein, the preferred vertical height H for headlight 10 i
within the range of from about only l.S to about 2.5 inches.
The corre~ponding width dimension (in a direction toward and
away from t~e viewer in FIG. 1) for the reflector'6 rectangular
opening i8 preferably within the range of from about only 2.0
to about 3.0 i~che6. Accordingly, headlight 10 possesses a
forward rectangular opening within the range of from only about
3.0 square inche6 to about 7.5 square inches. As a result, the
ratio Or such a rectangular open area to the relatively short
focal length of reflector 11 is within the range of from about
6:1 to about 37.5:1.
EXAMPLE
In one example of the invention, a headlight was
made wherein the plastic reflector po66es6ed a
rectangular opening having a height of about 2.0
inches and a correspondence width of 2.5 inches. The
corresponding focal length was only about 0.30 inch
and the filament's length to diameter ratio was an
ideal 1:1. The coil po6sessed an outer diameter of
about 0.065 inch. The capsule secured within the
reflector, having an axially aligned coiled-coil
tung~ten filament, was operational at a wattage of
only about 20 watts. The planar cover which provided
the closure for the reflector's rectangular openinq
was of glas6 material and included the aforedescribed
internal lensing elements.
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D-84-1-159 -l2- PAT~NT
A6 illu~trated by the above example, the lighting
cap6ule i8 operational at low wattage6. 8y low wattage i6
~eant a wattage within the range of from about ten to
about twenty-five watt~. In addition, headlight 10 i6
preferably utilized in combination with at lea6t three
additional 6imilar comeonent6 to form an overall array of
four 6uch component6. Two 6uch array6 are utilized per
vehicle, with each array being po6itioned on one 6ide
thereof. Even further, each of the6e headlight6 i6
preferably arranged in a horizontal, planar orientation
6uch a~ depicted in U.S. Patent 4,545,001. Thi6 i6 not
meant to limit the invention, however, in that the6e
array6 may be 6ucce66fully arranged in different
orientation6 to thu6 accommodate the vehicle'6 forward
6hape.
Cap~ule 27 i6 oriented within reflector ll 6uch that
the pre66 6ealed end 35 i6 located within (and 6urrounded
by) the extending neck portion 17. Thi6 arrangement
6erve6 to 6ub6tantially prevent light 6catter from
headlight 10 whicb in turn can contribute to the
aforementioned glare problem. The pre66 6ealed end 35 of
a cap6ule ~uch a6 depicted herein will adver6ely effect
the cap6ule'6 light output. Accordingly, po61tioning of
~- thi6 part of the cap6ule within a rece66ed area of the
reflector 6erve6 to prevent 6uch 6cattering, particularly
it the internal 6urfaces of the neck portion 17 do not
include a reflective coating thereon, It i6 6een in YIG.
3 that the de6cribed reflective coating lS does not extend
into thi6 rece66ed area of the reflector. The above
~- 30 positioning relation6hip thu6 6erve6 to further a66ure
` opti~u- light output for the in6tant invention.
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D-84-1-159 -13- PATENT
With particular attention to FIG. 4, there i8 provided
a chart which illustrates the relation~hip between
relative light output in compari60n to the ratio of
filament length to diameter for the low wattage coils.
Specifically, it i~ seen that a relatively high ratio of
about 4:1 provide~ about twenty percent le~ relative
ligbt in compari~on to an ideal ratio of l:l as taught
herein. This light output i8 measured within a field of
from 0 to a negative 4.25 with respect to horizontal.
The 0 coor~inate of the field is tha~ horizontal line
which intersect6 the optical axis of the headlight when
the headlight i~ faced in that direction. Accordingly,
the negative 4.25 coordinate i6 that horizontal line at
approximately 4.25 below the horizontal 0 line. This
field understandably is located at a distance forward of
the headlight.
In PIG. 5, there is 6hown a filament structure 31~ in
accor~ance with a preferred embodiment of the invention.
Filament 31' i6 of coiled-coil con6truction and produced
; 20 from tungsten wire. Por~ation is achieved by winding thi6
- wire about a suitable mandrel (e.g., molybdenum rod) to
form a single coiled member. This structure i8 then
formed (coiled) to provide the shape depicted in FIG. 5.
A suitable high temperature wax is then applied to the end
segments ot the structure and the ~tructure is then acid
etched to remove the mandrel, excluding of course the
- protected ena segments. Accordingly, the mandrel rod
sections 41 remain in place and are surrounded by the
respective internal ends of lead-in conductors 37'. The
resulting coiled-coil filamentary material is axially
orientoa along the optical axis OA-OA as shown, as well as
boing ~ontorod at focal point PP. Uniguely, the
m4n~rol-~ont4i~ing on~s are not activated (do not glow)
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D-Bq-1-159 -14- PATENT
upon filament energization due to the thermal ~quenching~
by tbe ~andrel material. Only the non-protected poction~
(defined cubctantially by tbe L and W dimen6ional arrows)
will glow auring energization. This unique arrangement
enable~ formation of a filament structure of coiled-coil
configuration wherein the ideal 1:1 ratio of length to
diameter i~ po~6ible, thu6 as6uring a 6ub~tantial point
source of light for reflector 11.
Utilization of a plurality (e.g., four) of headlight6
of the type defined herein within each of two 6paced
array6 for a motor vehicle provide6 ~everal advantages
over many known prior art 6y6tems. Fir6t, the u~e of
multiple 60urce6 Or the number mentioned provides desired
re~undancy in that more than one 6ection of the overall
sy6tem provide6 illumination to the 6ame region of space
(forward pattern). Thu6, should one headliqht fail (e.g.,
burn out), a ma30r portion of t~e forward light pattern
will not be totally 106t a6 i6 the 6ituation with many
exi~ting headliqht sy6tems (typically including a total of
only two or four headlights). In the instant invention,
about ~eventy-five percent of the total coverage for any
given forward component remain6 upon the failure of a
singlo headlight in the system. Second, it is
acknowledged that only certain parts of the headlight
rerl~ctor provide beam element6 suitable for developing
the ~igh inteQ6ity gradients required for the 6harp
cut-off of the low beam pattern near the horizontal plane
through the vehicle'~ light 60urce. A greater percentage
of the net reflector area for developing high inten6ities
near the horizontal with minimal glare in the upper left
quadrant ttoward oncoming driver6) is possible utilizing a
hoadlight a~ defined herein in view of the utilization of
~e~ral in~ ual reflector olement6. Thirdly, an
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D-84-1-159 -15- PATENT
increase in the number of individual headlight unit~ in
turn increases the 1eYibility of optimizing both high and
low beam~. This is possible by switching (activating)
selected headlight unit~ for either high or low beam or
leaving other unit6 energized for both patterns. Pre~ent
headlight 6y~tem6 in which two filament6 are activated in
a 6ingle len6-reflector headlight unit do not typically
pos~e~ ~uch flexibility. With the~e exi6ting ~y~tem6,
the len6 element6 can be optimized for only one pattern
and switching to a 6econd filament produce6 at best a
compromised light distribution.
Pourthly, the small vertical aimension ana the freedom
to configure variou6 arrangements of a plurality of small
headlamp6 a6 taught herein enhance6 the ability to form
- 15 aerodynamic front end6 for vehicle6 utilizing the
~ invention.
There ha6 thu6 been 6hown and de6cribed a motor
vehicle headlight wherein the reflector po6~e~se6 a
~ relatively 6hort focal length and the coiled filament
utilized in the headlight's lighting source (cap6ule)
po6~e66es alreaay a preaetermined length to diameter ratio
le~6 tban about 2:1) 80 a6 to provide optimum light
output for the headlight ~uch that a fini6hed product
having a ~mall vertical height (e.g., about two inches)
can be produced. The above optimum light output is
po~ible through the teaching6 herein wherein the
hoadlight'6 reflector po66es6es a relatively small forward
openinq in combination with the defined short focal length.
While there have been shown ana de6cribed what are at
present con6iaered the preferred embodiment6 of the
invention. it will be obviou6 to tho6e s~illed in the art
that variou~ change6 ana modification~ may be made therein
w~thout departing ~rom the 6cope of the invention as
defined by the appended claim~.
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