A lamp having a treated lense for reducing peripheral glare thereby making the lamp useful as a driving light, fog light or spotlight. The treated lense is provided with opaque pigment around the periphery of the lense and the center portion thereof to form elliptical shaped aperture for more acutely defining the desired beam pattern.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to electric lamps and more particularly, but 
not by way of limitation, to a lamp having a treated lense to reduce 
peripheral glare primarily for use as automobile or vehicle driving lamps, 
spotlights or the like. 
2. History of the Prior Art 
There is a well developed history of utilization of lamps for spotlights or 
driving lamps where the lamp includes an internal parabolic reflecting 
surface for collecting the light emission from a bulb or resistive element 
located near the focus of the parabolic surface, collimating the light 
into a beam which is directed through the lense or suitable transparent 
media to illuminate a specific viewing area. 
Since the lense is usually refractive and the parabolic surface is often 
slightly open to provide a desired beam pattern, there exists peripheral 
illumination outside of the beam width in which the light is less intense 
and which is even desirable for many ordinary uses. 
However, when such lamps are used as driving lights for vehicles in fog, 
smoke or rainy conditions, reflection from the peripheral illumination is 
distractive and actually impairs visibility in the desired viewing area. 
A particularly successful attempt was made to overcome the above 
disadvantages by the patent to Hulbert, U.S. Pat. No. 3,754,135, issued 
Aug. 21, 1973, for "Light Treating Means." The Hulbert device teaches the 
treating of the light by coating specific areas of the lense with a blue 
translucent pigment whereby the teaching indicates that a "light mixing" 
takes place which serves to change the color spectrum and to reduce glare. 
While glare is in fact reduced by the Hulbert device, a great amount of 
peripheral illumination is still present which can and does present some 
problems when the lamp is used in conditions of fog, smog, rain or on wet 
surface. 
On the other hand, by utilizing the blue mixed light, there is an 
enhancement in color differentiation and object identification within the 
illuminated beam pattern of light. 
Another problem exists with the Hulbert device when used as a vehicle head 
lamp that is that the primary beam is surrounded by a reflected blue halo 
during use in highly reflective environments which can be distractive to 
approaching motorists as well as to the driver of the vehicle. Also, since 
the Hulbert lamp appears blue during daylight conditions as well as when 
used in a highly reflective environment, its use is prohibited under many 
state laws in which blue has been adopted for use by law enforcement 
vehicles only. 
SUMMARY OF THE INVENTION 
The present invention provides a lamp which has been particularly designed 
to produce a substantially white light which illuminates a defined area 
and wherein the peripheral illumination is virtually eliminated. 
The present invention utilizes a lamp whereby the lense element of that 
lamp is treated in order to more acutely define the beam pattern and 
thereby reduce glare. The outer peripheral lense element which is usually 
circular in shape (but need not be) is coated with an opaque pigment which 
may be black, leaving an elliptical shaped aperture with the major axis 
thereof being horizontally oriented. The center portion of the lense is 
then coated in a like manner to provide an elliptical shaped opaque center 
portion, again with its major axis being horizontal. This provides an 
elliptical shaped light aperture in which the lense is untreated. 
In order to coat the lense in a manner so that the coating is durable, the 
areas to be coated are first frosted by either etching or sandblasting. 
The pigment is then applied to the frosted area. The resulting lamp 
provides a more acutely defined beam pattern than that of the blue coated 
lamp or the untreated lamp even though there is a reduction in the ability 
to distinguish color of objects within the beam pattern. Since the beam 
pattern is more acutely defined, incident light is reduced and the edge 
glare is virtually eliminated. 
Testing has revealed that the center portion of the translucent blue coated 
bulb has incident light surrounding the main beam pattern, whereas, the 
black or opaque coated lamp has a very defined main beam pattern. 
In summary, the black or opaque coated lense will not produce the same 
effects as the blue such as color identification and objection definition 
but the beam pattern will eliminate the glare thereby making the present 
invention more desirable as a driving light in highly reflective 
conditions. 
Other tests have indicated that by similarly coating the clear lense, one 
with a blue translucent coating and the second with opaque coating, the 
blue unit has approximately 28% less maximum output than the clear lense 
while reducing peripheral or stray light by an amount of some 50%. The 
opaque light compared with the blue light displayed 90% of the intensity 
of the blue light but only 30% of the stray light. Hence one might deduct 
that the peripheral light or stray light from the opaque treated lense 
would amount to 15% of that present in a clear or untreated bulb while 
still maintaining approximately 65% of the intensity output in the desired 
viewing area. 
Hence, it was determined that the lamp with the opaque treated lense as 
taught by the present invention was significantly superior over either the 
clear lense or the blue coated lense when used as a vehicle auxiliary 
driving lamp.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings in detail reference character 10 generally 
indicates a lamp which may or may not be of a sealed beam type having a 
lamp body 12, the inside surface 14 thereof being reflective and in the 
shape of the parabaloid. The lamp 10 also comprises a light emitter which 
is normally of a resistive element type indicated by reference character 
16 and is normally located near the focus of the parabolic surface 14. The 
light emitter is provided with a filament shield 15. The parabolic surface 
14, upon receipt of the light from the light emitter 16, reflects that 
light or collimates the light into a beam which is then transmitted 
through a lense or transparent media generally indicated by reference 
character 18 being disposed to cover both the reflecting surface 14 and 
the light emitter 16. 
Although the lense need not be constructed of glass material, glass 
material is a common media for the lense and is indicated by reference 
character 20. The front surface of the lense 20 is then treated in the 
following manner: 
First, the specific areas of the lense to be coated are frosted by either 
an etching process or by sandblasting, the first such frosted area being 
represented by reference character 22 and covering the outer peripheral 
area of the lense leaving an enlarged elliptical shaped aperture 20 
therein. A second center portion of the lense 26 is frosted in a like 
manner and in the shape of an ellipse which is concentric within the 
elliptical aperture resulting from the frosted area 22. 
After the areas 22 and 26 have been frosted, there remains an elliptical 
shaped untreated area 28 which will be referred to as an elliptical shaped 
aperture. After the areas 22 and 26 have been frosted they are coated with 
an opaque pigment which may be black, but not limited to black and is 
indicated by reference character 30. 
Referring now to FIGS. 3, 4 and 5, FIG. 3 represents a beam pattern of an 
Optronics 7706 bulb having an untreated or clear lense. It is noted at the 
outset that the subject 7706 lamp has provided in the lense, an array of 
facets or flutes for refracting portions of the beam to make the lamp 
suitable as a driving lamp. For instance as shown in FIG. 3, the left 
portion of the pattern is somewhat chopped to control the amount of 
peripheral light to the left and is particularly designed for use as a 
vehicle driving lamp in areas where vehicles are driven in the right hand 
lanes of traffic. This chopping prevents excessive beam pattern into 
opposing lanes of traffice. Further, by way of definition, each of the 
patterns displayed in FIGS. 3, 4 and 5 are conducted with an Optronics 
7706 lamp treated in the methods that have been heretofore described. The 
contours depicted in the beam patterns are in foot-candles and represent 
light intensity over the various contours. 
It can be seen that the primary beam pattern consisting of 10,000 
foot-candles or greater for the clear bulb as shown in FIG. 3 extends some 
31/2.degree. to the left, 51/2.degree. to the right, 21/2.degree. upward 
and just over 3.degree. downward. It can also be seen that peripheral 
light represented by the 500 foot-candle contour extends some 10.degree. 
to the left 4.degree. upward, is off the chart in a downward direction and 
again off the chart in a right-hand direction. This peripheral light 
represents the peripheral illumination giving rise to edge glare when used 
in a reflective environment such as fog, smoke, rain, snow and the like. 
Referring now to FIG. 4, which is representative of a translucent blue 
coated bulb, it can be seen that the primary beam pattern represented by 
10,000 foot-candles or greater extends almost 3.degree. to the left, 
41/2.degree. to the right, 21/2.degree. upward and approximately 
21/2.degree. downward. Peripheral light of 400 foot-candles or greater is 
shown as extending some 11.degree. to the left, 41/2.degree. upward, off 
the chart in a downward direction and also off the chart in the right-hand 
direction. 
Referring now to the beam pattern of FIG. 5, which represents the pattern 
provided by a bulb having been treated in accordance with the teachings of 
the present invention, the primary beam pattern represented by 10,000 
foot-candles or greater extends some 21/2.degree. to the left, 
31/2.degree. to the right, 2.degree. upward and 2.degree. downward. This 
represents a more defined primary beam pattern than either the blue coated 
bulb or the untreated bulb. A contour of 400 foot-candles or less has been 
plotted on the beam pattern of FIG. 5 showing that contour to extend some 
91/2.degree. to the left, 131/2.degree. to the right, 21/2.degree. upward, 
and 5.degree. downward. 
It can also be seen that the 400 foot-candle contour for the beam pattern 
depicted in FIG. 5 more tightly conforms to the directional axis on the 
upper side of the pattern. Stated another way, from approximately 
3.degree. to 91/2.degree. to the left of center, the 400 foot-candle 
contour extends less than 1.degree. in an upward condition as is the case 
from between 5.degree. to 13.degree. to the right of center. It is also 
noted that this area is the area most likely to provide poor visibility 
when used in highly reflective conditions. 
It can be seen by comparing the three beam patterns provided, that the 
coatings applied in the teachings of the present invention provides a more 
acute and distinct beam pattern which greatly eliminates edge glare which 
is produced by peripheral light surrounding the main beam pattern. 
Referring now to the curve of FIG. 6, the abscissa depicts the visible 
color spectrum beginning with the ultra violet or blue at approximately 
410 nanometers wave length extending to the opposite end of the visible 
color spectrum in which the beginning of infrared starts at about 660 
nanometers and wave length. Tests have been made to determine perceptible 
color differences to the human eye for each of these wave lengths wherein 
the noticeable difference distinguishable by the human eye is plotted on 
the ordinant of the graph. Hence the ordinant represents the noticeable 
color difference compared to the various color wave lengths. 
It has further been determined that objects illuminated by light having a 
tinge of yellow represented by approximately 540 nanometers is less 
distinguishable than light which has a tinge of yellow and is then mixed 
with blue. The central beam pattern produced by the opaque coated bulb as 
shown in FIG. 5 provides substantially white light in the center portion 
thereof where the outer edges thereof will be tinged yellow. 
On the blue coated bulb as shown in FIG. 4, blue light is mixed with this 
yellow tinge which produces a slightly blue green color which yields 
better color differentiation. Tests have indicated that color 
identification using the blue coated bulb is better by approximately 30 to 
35% over the black coated bulb. However, as stated above, the primary 
purpose of the opaque coating as taught in the present invention is to 
reduce glare and provide a more acutely defined beam pattern which can be 
played on the roadway immediately ahead of the vehicle. 
Referring now to FIG. 7, a second embodiment of the bulb is identified by 
reference character 32 in which the outer peripheral opaque coating 34 and 
the central opaque coating 36 is circular in shape thereby providing an 
annular clear aperture 38. Naturally the circular pattern may be 
considered as a special case of ellipse in which the eccentricity is zero. 
It should be noted that other lenses than those described herein may 
require the peripheral and central coating to take on shapes different 
from the elliptical and circular shapes described and can best be 
determined by optical testing. 
From the foregoing, it is apparent that the present invention provides a 
lamp which is particularly designed to produce an acute beam pattern and 
wherein the peripheral illumination or incident light has been greatly 
curtailed which results in reduced glare in adverse visibility conditions. 
Whereas, the present invention has been described in particular relation to 
the drawings attached hereto, other and further modifications apart from 
those shown or suggested herein may be made within the spirit and scope of 
the invention.