U.S. patent number 3,633,022 [Application Number 04/882,997] was granted by the patent office on 1972-01-04 for lamp.
Invention is credited to Knut Otto Sassmanshausen.
United States Patent |
3,633,022 |
Sassmanshausen |
January 4, 1972 |
LAMP
Abstract
A double-beam lamp, such as a taillight or warning light has a
collective lens bulb in the axis of a surrounding reflector in
whose focal space, the luminous wire of the lens bulb is located.
The collective lens projects a first beam, and the reflector, whose
shape deviates from a geometrical parabola, projects a second beam,
and while one of the beams is made narrow and conical, the other
beam is spread in horizontal direction by a cylindrical dispersing
lens over a wide angle for lateral visibility while remaining
narrow in the vertical direction to avoid loss of light.
Inventors: |
Sassmanshausen; Knut Otto
(Rothenbach, DT) |
Family
ID: |
25381780 |
Appl.
No.: |
04/882,997 |
Filed: |
December 8, 1969 |
Current U.S.
Class: |
362/327;
359/721 |
Current CPC
Class: |
F21S
41/168 (20180101); F21S 43/40 (20180101); F21V
5/08 (20130101); F21S 41/162 (20180101); F21S
41/166 (20180101) |
Current International
Class: |
F21V
5/00 (20060101); F21V 13/00 (20060101); F21V
13/04 (20060101); F21S 8/10 (20060101); F21V
5/08 (20060101); B60q 001/30 () |
Field of
Search: |
;240/8.3,41,41.3,41.35,46.45,106.1,7.1,41.65,10.69,151
;350/194 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
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108,616 |
|
Jan 1968 |
|
DK |
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455,934 |
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Jul 1968 |
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CH |
|
Primary Examiner: Capozi; Louis J.
Claims
1. Double-beam lamp, particularly for use as taillight or warning
light, comprising a collective lens, and a luminous body located in
the axis of said lens between the same and a focal point of the
same so that a first conical beam of light is projected by said
lens; a concave substantially paraboloid reflector surrounding said
lens and said luminous body and having an axis coinciding with said
axis, sections of said reflector deviating from a parabola having
an exactly geometrical shape so that said reflector has a focal
space extending along said optical axis a distance between 3
percent and 10 percent of the diameter of the open end of said
reflector; said luminous body being at least partly located in at
least a part of said focal space of said reflector so that a second
conical beam of light surrounding said first conical beam is
projected by said reflector toward said open end of said reflector;
and an optical dispersing system located at said open end for
dispersing at least one of said conical beams only in one direction
a wide angle so that an oblong area extending in said one direction
is illuminated by said dispersed beam, while a substantially
circular area at least partly coinciding with the central portion
of said oblong area is illuminated by the other beam.
2. Double-beam lamp as claimed in claim 1 wherein said optical
dispersing system includes a transparent cover plate for closing
said open end of said reflector and including a central portion
aligned with said collective lens and passed by said first beam,
and an annular portion passed by said second beam; and wherein one
of said portions is a
3. Double-beam lamp as claimed in claim 1 wherein said dispersing
system includes a substantially cylindrical dispersing lens which
is thinnest along a centerline transverse to said optical axis and
to said one direction, and uniformly increases in thickness in said
one direction
4. Double-beam lamp as claimed in claim 3 wherein said
substantially cylindrical dispersing lens is located in front of
only said collective lens aligned with the same so that said first
beam passes through said
5. Double-beam lamp as claimed in claim 3 wherein said
substantially cylindrical dispersing lens is located in front of
said open end of said reflector so that said second beam passes
through said dispersing lens and
6. Double-beam lamp as claimed in claim 1 wherein said dispersing
system
7. Double-beam lamp as claimed in claim 1 wherein said concave
reflector is composed of a plurality of annular paraboloid
reflecting zones having
8. Double-beam lamp as claimed in claim 7 wherein the transitions
between said reflecting zones and the paraboloid shape of the same
are selected so that said focal points form a focal line extending
along said optical
9. Double-beam lamp as claimed in claim 1 wherein said reflector is
composed of a plurality of annular planar reflecting surfaces
connected to each other so that said planar reflecting surfaces
together approximate a
10. Double-beam lamp as claimed in claim 9 wherein said planar
reflecting
11. Double-beam lamp as claimed in claim 1 wherein said first
conical beam has in a plane extending through the optical axis of
said collective lens and in the longitudinal direction of said
luminous body, which is disposed at right angles of said axis, an
aperture angle at least 1.3 times greater than the corresponding
angle of aperture at right angles to the longitudinal direction of
said luminous body; wherein said collective lens and said luminous
body are combined in a bulb; and comprising a holder for said bulb
fixing the angular position of the axis of said bulb and of
said
12. A lamp as claimed in claim 11 in which the aperture angle of
the conical light beam to be produced by said collective lens of
the bulb in the plane extending through the optical axis and the
longitudinal direction of said luminous body, is 1.5 to 2.5 times
larger than the corresponding aperture angle at right angles to the
longitudinal direction
13. A lamp as claimed in claim 11, in which the luminous body of
the lens bulb has a ratio of length to external diameter of more
than 10:1, and its central portion deviates from the line
connecting the end portions of the section which glows in operation
by at most 22 percent of its length, its longitudinal direction
being arranged approximately at right angles to the
14. A lamp as claimed in claim 11 in which said luminous body is
arranged
15. A lamp as claimed in claim 14 wherein said luminous body has at
its central portion a smaller spacing from a plane extending
through the
16. A lamp as claimed in claim 11 in which said lens bulb is
provided with a prefocusing miniature base flange, and in which the
angular position of the axis of said bulb is fixed by a projection
of said holder engaging a
17. A lamp as claimed in claim 1 wherein said reflector has at
least one peripheral sealing surface, and comprising a closure cap
having a sealing surface in sealing contact with said peripheral
sealing surface of said
18. A double-beam lamp as claimed in claim 1 wherein said
dispersing system includes a substantially cylindrical dispersing
lens which is thinnest and plane parallel in a circular central
portion axially aligned with said collective lens and uniformly
increases in thickness in said one direction toward opposite sides
of said dispersing lens; wherein said collective lens projects said
first conical beam through said thin plane-parallel center portion;
and wherein said second conical beam passes through the outer
annular portion of said cylindrical dispersing lens and is
dispersed
19. A double-beam lamp as claimed in claim 1 wherein said
dispersing system includes a transparent plane-parallel plate
having a center portion which is a substantially cylindrical lens
aligned with said collective lens along said optical axis and
uniformly increasing in thickness in said one direction toward
opposite sides of said cylindrical lens; wherein said collective
lens projects said first beam through said cylindrical lens;
wherein said second conical beam passes through said plane-parallel
plate; and wherein said first beam is dispersed by said cylindrical
lens in said one direction.
Description
The invention concerns improvements in or relating to lamps with a
light source and two optical collective systems, one of which is a
concave reflector and the other a lens. It is particularly suitable
for use as a rear or safety lamp, taillight or warning light. Such
lamps are known and are advantageously used in torches and the like
devices. They have the advantage of delivering a relatively high
concentration of light with a limited supply of power.
In known lamps the requirement exists of projecting a maximum
amount of light onto a limited surface in order to illuminate this
surface well. There are, however, cases in which not the
illumination of a surface but the visibility of the light source is
important. This applies, for example, to bicycle rear lamps and to
so-called warning flash lamps which are usually fed from
batteries.
In many cases, particularly in rear and warning lamps, two light
reflecting zones are necessary:
First a principal light beam is required, which is intended to
cover an area of .+-.10.degree. on either side of the horizontal
and the vertical, in a direction opposite to the direction of
travel. This corresponds to a light beam cone with an aperture
angle of about 28.degree.. It serves in rear and safety lamps to
make the lamp visible to traffic coming from behind, in so far as
such traffic follows approximately the main direction of traffic.
This main beam has to meet the highest demands as regards its light
intensity in order to make such a lamp visible over as long
distances as possible.
On sharp curves or for traffic turning in from the side, this angle
is indeed sufficient vertically but it is not sufficient
horizontally. For this purpose a second light reflecting zone also
of about .+-.10.degree. is required on either side of the
horizontal plane through the reflector axis, but about
.+-.45.degree. on either side of the vertical plane through the
reflector axis opposed to the direction of travel. For a cone of
light with a uniform aperture angle as in the first case, this
would require an aperture angle of about 95.degree., whereupon all
the light above and below 10.degree. from the horizontal would be
lost to the second light beam since it would be directed either to
the road surface or, far above the following road users, into the
air. A differently arranged second light beam has thus to be
provided.
Accordingly it is an object of the invention to concentrate as
great a proportion as possible of the light emitted from the light
source, and to direct it into the two zones in which the light is
required for the above purpose. The invention provides new means of
achieving this purpose, with great optical efficiency and
economy.
According to the invention there is provided a lamp, suitable for
use as a rear or safety lamp comprising a light source and two
optical collective systems, one of which is a concave reflector and
the other is a lens, wherein the concave reflector is parabolic and
has axial sections deviating by so much from the ideal shape of a
parabola that it has a focal space instead of a focal point, the
extent of which in the reflector axis is at least 3 percent and
preferably 5 to 10 percent of the largest diameter of the reflector
aperture, a lens bulb being so mounted with its lens coaxial with
the concave reflector that at least a part of the luminous body of
the lens bulb fills at least a part of the focal space as a result
of which, in operation, a reflected conical light beam is formed
whereas the luminous body of the lens bulb is so disposed between
the lens and the inner focal point of the lens that a second
conical light beam will be formed, an optical system serving to
disperse light into two directions which extend oppositely in one
plane, being disposed in front of only a part of the two optical
collective systems, preferably of only one of the systems.
Theoretically parabolic reflectors have a focal point at which all
parallel light beams incident on this reflector are combined.
Practically, when using light which is incident strictly parallel
on an optical bench, instead of a focal point an approximately
spherical "focal space" will be present the maximum dimension of
which is for example, about 1 percent of the extent of the
reflector aperture. Within the scope of the present invention an
attempt is made to increase the extent of this focal space to more
than 3 percent, preferably to 5 to 10 percent of the maximum
dimension of the aperture of the concave mirror this extension of
the focal space need not necessarily be at right angles to the axis
but it can also extend in the axis so that the focal space becomes
linear.
The conical light beams spread out from the reflector and from the
lens, and outside the reflector both a conical principal light beam
with an aperture angle of about 28.degree., as well as a flat
secondary light beam widened to e.g., about 90.degree. are
obtained. The two light beams preferably have approximately the
same axis.
A slightly conically concentrated light beam emerging from the
whole system is produced by the lamp according to the invention,
which first beam is directed, for example, opposite to the
direction of travel so that any vehicles which approach at high
speed and can only turn aside with difficulty, are warned in good
time. Additionally, however, a second light beam zone is produced
on both sides for sharp turns or for traffic entering from the
side; this light beam zone has approximately the same extension in
the upward and downward directions as the first light beam, but
laterally it is widely spread so that the merging traffic or the
like, which can turn aside more readily than the traffic
approaching in the direction of travel, has the possibility of
avoiding the warning flash lamp, rear lamp or the like. Regulations
for a rear lamp require at present that this lamp has to illuminate
10.degree. in the upward and 10.degree. in the downward directions
in order to compensate for height differences in this way to a
sufficient extent. In contrast an angle of 45.degree. on either
side of the direction of travel has proved itself for the broad
beam emitter. The two light zones overlap. Since it is now always
intended to obtain a light zone of .+-.10.degree. for the conical
light beam within a lateral area of .+-.10.degree., an aperture
angle of about 28.degree. for the conical light beam results from
the diagonal of the square thus determined.
It would be easy to carry out the limitation of the broad light
beam in the upward and downward directions by masking; it is,
however, desirable that this light above and below the angle of
10.degree. should not be lost but that it be made likewise
available to the broad beam. The various features of the object of
the invention serve in particular for this purpose.
A converging light beam is produced by the lens in a simple manner
in that the filament is arranged between the lens and the focal
points of the lens. In a similar manner, a divergence of the light
beam emitted by the concave reflector is caused by a displacement
of the filament or of the whole lens bulb with respect to the
concave reflector, but this has the disadvantage that the intensity
of the light in the axis of the conical light beam is considerably
reduced. It is therefore more advantageous to provide the reflector
not with a defined "focal point" but with the above-described,
mathematically less definite "focal space," the extent of which in
the direction of the axis of the reflector is at least 3 percent,
preferably 5 to 10 percent of the largest diameter of the reflector
aperture. In front of these two optical collective systems which
produce slightly diverging cones of light, there is to be disposed
within the scope of the invention, an optical system which
disperses light in two opposite directions extending, however in
one plane, this system producing the broad beam. This dispersing
system acts only on a part of the two optical collective systems so
that a particularly bright principal beam is obtained; preferably
it acts only on one of the two systems so that the other system is
used exclusively for producing the brighter principal beam.
The dispersing system is preferably associated with the
conventional cover plate of the concave reflector and
advantageously forms a part thereof. Since such cover plates are
generally pressed from a plastics material or from glass and in
many cases have a special shape no special difficulties arise in
making this cover plate of such a shape that it or a part thereof
serves as a dispersing system. The dispersing system is
conveniently a substantially cylindrical dispersing lens which is
thinnest in the center (i.e., in a straight line perpendicular to
the optical axis) and if desired, is plane-parallel and then
increases in thickness on both sides of the centerline uniformly,
preferably continuously.
The slight divergence which, according to the invention, should be
effected by the concave reflector, can be obtained in that, e.g., a
concave mirror which is parabolic in axial section, is resolved
into several annular zones, each of which has its own focal point.
A row of different focal points, i.e., a kind of a focal space is
thus formed. If the annular zones are chosen as small as possible
in their dimension extending parallel to the optical axis of the
reflector, and smooth mergings between them are provided, as is
quite possible in pressed plastics mirrors lined with metal, a
"focal line" approximately coinciding with the optical axis is
obtained, which is particularly advantageous for the present
purpose because this line produces in the principal light beam
(aperture angle about 28.degree.) an extremely uniform distribution
of light. Another possibility consists in that an imaginary
paraboloid of revolution is associated with tangential mirror
surfaces, preferably planes of an e.g., hexagonal shape. The small
surfaces can contact the imaginary paraboloid of revolution at
their centers. The size (in mm..sup.2) of the so arranged
tangential surfaces should advantageously be determined by the
equation F = nQ/cp in order to obtain a sufficient focal space for
the given aperture angle of the light beam: the distance n between
the tangential point situated on the paraboloid of revolution and
the focal point of the paraboloid measured in mm. is multiplied by
the desired aperture angle Q in degrees; divided by cp, where c is
a nondimensional constant and the value p is the angle in degrees,
at which the luminous body appears in its maximum dimension as seen
from the apex of the paraboloid c can readily be determined by
trial and error for any type of construction. In both methods
described in detail, at least a part of the luminous body must be
arranged in the focal space. Any desired aperture angle for the
light beam emitted by the reflector can thus be obtained while
omitting the decrease of light intensity towards the axis, which is
known in paraboloid mirrors with a defocused source of light.
The second optical collective system is the lens of the lens
bulb.
A dispersing system acting only in the horizontal direction is
disposed in front of only one part of the two light beams, as a
result of which the flat conical light beam is formed, whereas the
other as the principal light remains preserved, wholly or
substantially unchanged.
Since as a rule it is possible to collect with the reflector a
larger spatial angular zone of the light emitted by the luminous
body than with the lens, the light emitted by the reflector will in
many cases be used as the principal light beam and will not be
dispersed in the horizontal direction. The light conveyed through
the collective lens will be dispersed in this case. However, also
the reverse way can be chosen if, e.g., a particularly large amount
of light is required laterally.
If only one of the two light beams is used for dispersing light in
the horizontal direction to an aperture angle of preferably at
least 90.degree., an aperture angle of 20.degree., after passing
through the collective system, would theoretically be sufficient
for this light beam. With a dispersion in only the horizontal
direction this results, however, in the intensity of light
decreasing very considerably towards the upper and lower edges of
the required horizontal angle, i.e., in the range of .+-.
10.degree.. This can be avoided very easily if one considers that
the amount of light which with a uniform distribution of light
passes through a cone with an aperture angle of, e.g., about
20.degree., is much greater in a range of, e.g.,
0.degree.-1.degree. on either side of the centerline than in a
range of 9.degree.-10.degree. on either side of the central line
(assuming an approximately circular cross section of the original
light beam). In order to keep these differences of the intensity of
light as small as possible within the cone of light drawn apart to,
e.g., 90.degree. within the intended horizontal angle of originally
+10.degree., the original angle of aperture of the cone of light,
prior to dispersion, will be made greater than 20.degree.,
advantageously about 30.degree..
Another feature which is often even more advantageous in respect of
the optical system consists in that the light beam collected by the
lens emerges therefrom with a greater aperture angle in the
horizontal direction than in the vertical direction. A ratio of the
aperture angles of the light beam in the vertical and horizontal
directions of 1:l.4, at least 1:3 already offers great optical
technical advantages. The best ratio is between 1:1.5 and 1:2.5. In
order to obtain this, a ratio of luminous body length to luminous
body diameter of more than 10:1 can be chosen. The thus-dimensioned
luminous body is then fitted between the focal point of the lens
and the lens at right angles to the axis of the lens, i.e., if
possible so that its central portion deviates from the connecting
line between its initial portion and its end portion by at most 22
percent of the length of the luminous body. Beyond this it can be
of great advantage not to shape the curvature of the luminous body
as has hitherto been usual, i.e., the central portion of the
luminous body closer to the lens than the end portions (luminous
body curved towards the lens) but to shape it exactly in the
opposite manner (luminous body is curved away from the lens). In
this manner differences of the aperture angles of the light beam
projected by the lens of 1:2 or even more can be achieved with the
direction of measurement on the light beam being rotated through
90.degree..
The orientation of the longitudinal direction of the luminous body
to the lamp should be determined precisely in that, e.g., both on
the base of the bulb, as well as on the holder (socket or the like)
of the lamp suitable means are provided. Particularly suitable for
this purpose is, e.g., the standard prefocusing flange base P 13.5
s (miniature flange base) since its flange is not completely
circular but has an opening into which a part of this holder of the
lamp case engages so as to determine the angular position to the
axis of the lens or of the hollow mirror.
In many cases it has become usual to shorten concave mirror
reflectors on two opposite sides by means of surfaces parallel to
the axis. If the luminous body is now placed in the axis of the
system at right angles to these surfaces, a considerably larger
amount of light is obtained from the reflector than in any other
angular position of the axis of the body luminous body even in the
absence of a collective lens and/or a dispersing system; and it is
possible to use the auxiliary means of the preceding paragraph for
the adjustment of the angular position of the axis of the luminous
body.
In the accompanying drawings a diagrammatic illustration of the
intended distribution of light is shown in FIG. 1. Various
advantageous embodiments of the invention are shown by way of
example diagrammatically in the other Figures in which:
FIG. 2 shows an axial section, in which the reflector produces the
principal light beam.
FIG. 3 shows the cover plate of FIG. 2 in plan view.
FIGS. 4, 5, 6, 7, 8, 9, show alternative sections through the cover
plate of FIG. 3.
FIG. 10 shows in axial section a lamp, in which the lens of the
lens bulb supplies the principal light beam.
FIG. 11 shows the cover plate of the lamp according to FIG. 10.
FIGS. 12, 13, 14, 15, 16 show alternative sections through the
cover plate of FIG. 11. FIG. 17 shows the plan view of the flange
of a prefocus stop base P 13.5 s.
Further, in FIG. 18 the upper portion of a lens bulb is constructed
especially for producing an asymmetric beam is shown in an axial
section.
FIG. 19 shows a closure cap for the reflector according to FIG.
10.
The portion 321 bounded by the line 331 is produced by the conical,
axially symmetrical principal light beam, whereas the portion 311
bounded by the line 301 is produced by the broad light beam of the
symmetrical dispersing lens. Measured in the vertical direction,
both portions are about 30.degree.. In the horizontal direction,
the portion 321 has the same angle, whereas the portion 311 extends
about 90.degree. in the horizontal direction and is thus produced
by a flat, broad beam. (The distortion of the circle 331 which
results, e.g., from the length of the light body is not taken into
consideration in the drawing).
According to FIG. 2 a lens bulb 1 is provided, which is provided
with the standard prefocusing flange base or stop base 2 which is
on the market under the name of P 13.5 s. The plate-shaped base
flange 3 of this base after being inserted through the cylindrical
recess 4 of the reflector projection 5, engages the stop surface 6
of the reflector and thus ensures a precisely predeterminable
position of the incandescent coil or luminous body 7 of the bulb 1
relative to the reflector 10. This body 7 has a ratio of diameter
to length of the incandescent portion which glows in operation of
about 1:20. It is only very slightly curved, i.e., its central
portion deviates from the connecting line of its two end portions
by only about 5 percent of the whole length of the body. It is thus
achieved that the collective lens 8 of the lens bulb 1 produces an
asymmetrical light beam which in the direction of the longitudinal
extension of the luminous body has an aperture angle of about
50.degree. and at right angles thereto an aperture angle of about
30.degree.. In order correctly to secure the angular position of
the wider aperture angle of 50.degree. with respect to the optical
axis, means are provided which are more fully explained later in
connection with FIG. 17.
The reflector 10 consists for example of plastic material and is
axially symmetrical. The aperture of the reflector 10 is masked by
a cover plate 9 which in its part disposed in front of the
collective lens 8 of the lens bulb 1 has a dispersing lens 11, the
shape of which will be explained more fully with reference to the
following Figures. Since this lens is intended to disperse to the
right and left and not axially symmetrically (but laterally
symmetrically), it is a double concave cylindrical lens having an
approximately double-grooved shape. Theoretically this "dispersing
lens" could extend from one reflector edge to the other and thus
also disperse a part of the light beam produced by the reflector
10. It has, however, proved to be advantageous to limit the
dispersion to one of the two light beams, here the light beam of
the collective lens 8 because the optical results can thus be
predetermined more exactly. The light rays collected by the
collective lens 8 of the lens bulb in a slightly divergent light
beam, are spread apart here by the dispersing lens 11 in the
horizontal direction to slightly over 90.degree., as a result of
which a flat, conical light beam is formed. The directions of some
rays of this light beam are represented by the arrows
12,13,14,15,16.
Turning now from FIG. 2 to FIG. 1, the boundary designated by 301
of the luminous surface 311 is obtained.
The reflector 10 of FIG. 2 has on its inner side a reflecting
coating 17. It consists advantageously of various annular zones
with different focal points succeeding one another for example, in
the axial direction. The transitions between the individual zones
are advantageously smooth so that a focal line extending in the
axial direction is formed. The focal point of the annular reflector
zone (in the lower part of the drawing) nearest (axially near) to
the bulb 1 is relatively far removed from the luminous body 7. The
succeeding zones have foci which progressively approach the
position of the luminous body 7. In the vicinity of the cover plate
9, an annular reflector zone is provided, through the focal point
of which the luminous body 7 of the lens bulb 1 passes. The effect
of this arrangement is apparent from the light rays
18,19,20,21,22,23. Those rays (18,19) which originate from zones,
the focal points of which are farthest removed from the luminous
body, enclose an aperture angle of about 30.degree.. This aperture
angle decreases through about 15.degree. to approximately zero. In
addition to the smooth transitions between the individual annular
reflector zones with different focal points, also the finite
dimension of the luminous body 7 (in contrast to a point luminous
body) ensures that the thus produced light beam will be
homogeneous. As can be seen in FIG. 2, the edge portion of the
cover plate 9, through which the reflected light rays pass, is
plane-parallel and thus does not influence their direction. The
above-mentioned rays 18 to 23 produce in FIG. 1 the light spot 321
with the boundary 331 which spot 321 advantageously projects
upwardly and downwardly slightly beyond the flat beam 301,311.
Since the lamps according to the invention are frequently exposed
to bad weather, it is advantageous to seal them in a weather
resisting manner. For this purpose the reflector boss 5 has an
outer thread 24, onto which an advantageously totally closed cap
(see FIG. 19) with an internal thread is screwed. An annular
sealing member, e.g., of rubber, can then be placed in front of an
annular stop member 25. Moreover the cover plate 9 is tightly
cemented on or welded on. Upon screwing the cap onto the reflector
10, this reflector together with its lens bulb 1 will then be
sealed in a completely watertight manner.
Instead of the above-mentioned reflecting annular zones, also a
plurality of tangentially arranged surfaces or planes can be
used.
FIG. 3 shows the plan view of the cover plate 9 of FIG. 2. Its
outer annular portion is plane-parallel and its central portion is
formed by the dispersing biconcave lens 11 with a circular boundary
line. For better understanding of this cover plate 9, various
sectional views have been taken through it along section lines
designated by the letters A-B, C-D, E-F, G-H, I-K, L-M, N-O, P-R,
U-V and S-T.
FIGS. 4 to 9 show these sections.
FIG. 4 shows the radial section through the cover plate 9 on the
line A-B. The plane-parallel edge and the double concave dispersing
portion can be seen.
FIG. 5 shows the radial section L-M which is at right angles to
that of FIG. 4. It can be seen that also here the dispersing lens
or groove is plane-parallel in section. If one follows the section
line L-M in FIG. 3 it will be noted that in the central portion the
dispersing lens is approximately plane-parallel and becomes thicker
from there towards either side, in the present case towards the
right as well as to the left, and on either face, i.e., becomes
double concave.
In FIG. 6 laterally offset sections C-D and F-E are shown, which
extend parallel to A-B. The section through the lens portion has
become shorter.
FIG. 7 shows sections N-O and R-P parallel to L-M, and also here
the plane-parallel appearance of the sectional plane can be
recognized; at these places, however, the lens is already much
thicker than in FIG. 5.
FIG. 8 shows sections G-H and K-I which extend parallel to A-B but
are even further out from the center so that the section through
the lens portion has become even shorter.
Finally in FIG. 9 shows the sectional plane which is formed by
sections on lines U-V and I-S. The sectional plane of the lens or
groove bounded by parallel lines, has here already attained almost
its final thickness.
FIG. 10 shows another embodiment according to the invention A lens
bulb 30 is supported by a prefocusing flange base or stop base P
13.5 s. The flange 32 of the base 31 engages the stop face 33 of
the reflector 35. The luminous body 34 is thus brought into a
precise position inside the reflector. In this case the luminous
body of the lens bulb 30 is strongly curved in order to be able to
produce a uniformly round light beam through the double convex
collective lens 36 of the bulb. The angular position of the axis of
the lens bulb 30 need not be determined specifically in this case
since the collective lens 36 supplied a uniformly round, conical
light beam which will no longer be dispersed. The cover plate 45
has a central portion 37 which is made plane-parallel, and through
which the light rays 38, 39, 40, 41, 42, 43, 44, concentrated by
the collective lens 36, and forming the main beam pass undisturbed.
Only in the edge regions through which the light rays collected by
the reflector 35 pass, is there a double-concave, gutter-shaped
dispersing lens 45, the boundaries of which in the region of the
intersected central portion 37 are indicated by broken lines. The
concave mirror reflector 35 having the shape of a paraboloid of
revolution is in this case resolved into a plurality of small
surfaces. At the point at which such a surface tangentially follows
the ideal shape of a paraboloid of revolution, the light rays are
directed parallel. This can be seen in rays 46 and 47 which extend
parallel before they research the double-concave dispersing lens 45
and are reflected in two opposite directions by this lens. In
contrast the light rays which fall on such a reflector surface
outside the tangential point, do not extend parallel but have
different angles of divergence of up to about 30.degree. in front
of the dispersing lens. They are then additionally refracted
further in two opposite directions by the dispersing lens 45. This
can be seen from rays 48, 49, 50, 51. The lamp shown in FIG. 10 can
also be provided with a reflector of the type shown in FIG. 2, and
conversely. Also in the lamp shown in FIG. 10, it is advantageous
to seal all the connecting points in a watertight manner. For this
reason the reflector projection has likewise a stop shoulder 52
surrounding it, in front of which a sealing ring can be placed. The
lamp can then be sealed watertight with a cap (cf. FIG. 19) which
can have a bayonet joint in the form of two projecting pins. These
pins are inserted into the guide grooves 53 and then secured by
rotation in the guide groove 54 which extends a short distance
around the axis. It is particularly advantageous to provide this
cap with the current supply terminals for the bulb, as shown by way
of example in FIG. 19.
FIG. 11 shows a plan view of the cover plate 45 of the lamp
according to FIG. 10. In the following FIGS. 12, 13, 14, 15, 16 the
sectional planes are shown, which are formed by sections on lines
C-D, E-F, G-H, I-K, L-M, N-O, P-R, U-V, S-T in FIG. 11. The section
A-B corresponds to the section according to FIG. 10. The section
L-M extending at right angles thereto is shown in FIG. 12. It can
be seen that the cover plate 45 has in the center the same
thickness as at 37 in FIG. 10; however, the cover plate is much
thinner at the edge since the lowermost line of the gutter-shaped
"dispersing means" extends herethrough. Starting from this
lowermost line the wall thicknesses increase on either side, as can
be seen from the section C-D/F-E (and FIG. 10). Only a central,
short, plane-parallel portion is still present there, and the
remainder is formed by the "dispersing gutter-shaped lens, the
"gutter direction" of which is to be imagined in this case at right
angles to the plane of the drawing of FIG. 13 (and FIG. 10). The
section G-H/K-I of FIG. 15 is even further out and no longer shows
a plane-parallel portion in the center.
The sections N-O and R-P (FIG. 14) which are parallel to L-M, are
still in the vicinity of the lowermost line of the "groove" so that
the central portion 37 appears somewhat thickened, but as compared
to FIG. 12 the thickness of the edge is already increased. In the
last two sections of FIG. 16 (U-V/T-S), the central portion is no
longer cut, and the parallel upper and lower boundary lines of the
dispersing lens are shown.
FIG. 17 shows a plan view of a commercial prefocusing stop base P
13.5 s. The peripheral base flange with its three points of support
61, 62, 63 can be seen. In addition the gap 64 of 90.degree. in
this base flange, provided for the present invention, particularly
for use according to FIG. 2, can be seen. The axial position of the
lens bulb can be fixed by means of this gap if a projecting portion
is provided on the associated stop face 6 of the reflector boss as
has already been described in the introduction.
FIG. 18 shows the upper part of a lens bulb. The largest diameter
of the collective lens 70 is indicated at A-B. The luminous body 71
is so mounted perpendicularly to the optical axis of the lens bulb
that its central portion is further from line A-B than its end
portions. Particularly large differences in the aperture angle of
the light beam projected by the collective lens 70 can thus be
obtained, dependent upon whether this aperture angle is measured in
the direction of the luminous body 71 or at right angles thereto.
Such a lamp is particularly suitable for a light according to FIG.
2.
FIG. 19 shows a closure cap 80 for, e.g., the reflector 35 in FIG.
10. The internal diameter of this closure cap 80 is, at 81, as
large as the outer diameter of the reflector boss of FIG. 10. The
bayonet pins 82 are introduced through the guide grooves 53 and
rotated into engagement in the peripheral groove 54. At the same
time a sealing ring is compressed between the edge 83 of the
closure cap 80 and the peripheral stop 52 of the reflector 35, in
order to make the unit watertight. At 84 the internal diameter of
the closure cap is reduced so that at 85 it has a value which
corresponds to the outer diameter of the compression spring 86 and
thus guides and aligns this spring in the axial direction. The end
87 of the compression spring 86 is intended to press the lens bulb
30 of FIG. 10 with its base flange 32 against the stop 33 of the
reflector 35 and thus ensure a secure seating of the lens bulb. If
the stop 33 of the reflector 35, as already proposed in the
introduction has a projection which engages in the gap 64 of the
base flange 60 in FIG. 17, the spring 86, due to its pressure on
the base flange, secures the lens bulb against being lifted off the
stop 33 and thus against rotation about the axis of the system. At
the same time the spring 86, the end of which facing the cap is
supported on the peripheral stop 88 of the closure cap 80, can also
serve as one of the electric current conductors. For this purpose a
current supply wire can be introduced through the hole 89 of the
closure cap 80 and be connected, e.g., soldered at 90 to the
compression spring 86. The hole 89 should preferably be slightly
narrower than the insulation of the current supply cable so that
the unit is sealed watertight. The same applies to the hole 91,
through which the second current supply wire is introduced, which
by means of the screw 92 is conductively connected with the small
contact plate 93 which is intended to press on the bottom contact
of the bulb 30 in FIG. 10. In the assembly, care should preferably
be taken that the holes 89 and 91, through which the current leads
enter, point downwardly so that moisture can run off downwardly.
For this purpose it is advantageous that the bayonet pins 82 and
consequently also the guide grooves 53 in FIG. 10 are offset with
respect to one another not by precisely 180.degree. but by a larger
or smaller angle so that the position of the closure cap 80 on the
base can safely be predetermined with respect to the direction of
the holes 89 and 91 since otherwise the closure cap can not be
placed onto the reflector. The example shown here is only one of
many possible examples; also, e.g., in front of the stop 33 in FIG.
10 a metal ring could be placed and the current supply wire thereto
could be introduced through a hole in the reflector boss. It is
also advantageous that the reflector should further have above the
sealing edge 52 a protective cover projecting above the sealing
position by means of which rain water is drained off above the
seal. It is, however, common to all examples that the reflector
itself is sealed watertight by means of the closure cap and an
additional e.g., casing can thus be omitted. This can be used
particularly well with plastics reflectors. This tight construction
can be used for all reflectors, thus, e.g., also for headlights
without a collective or dispersing lens.
All the lens bulbs shown here are provided with a frame support
because the precision of the lamp can be achieved most easily
therewith. In so far as the necessary precision in the position of
the filament can also be obtained by other means, also bulbs
without a support can, however, be used.
* * * * *