U.S. patent number 3,764,800 [Application Number 05/298,199] was granted by the patent office on 1973-10-09 for cover plate for a lamp.
This patent grant is currently assigned to Trilux-Lenze KG. Invention is credited to Friedrich Clostermann.
United States Patent |
3,764,800 |
Clostermann |
October 9, 1973 |
COVER PLATE FOR A LAMP
Abstract
A cover plate for a lamp, formed on its surface with centrically
symmetrical light-refractory configurations. The entire surface of
the plate is traversed in at least three different angular
directions by straight, parallel ribs of simple or modified
V-section, of which the vertex lines defining the crests of the
ribs divide the plate, when viewed in plan, into principal
divisions in the form of hexagon, octagon or decagon depressions
with intervening secondary divisions in the form of smaller
triangular depressions and possibly polygon depressions, and the
cross-sectional shape of the ribs gives rise to the formation of
prismatic depressions in the form of inverted principal and
secondary pyramids in the principal and secondary divisions which
form their bases.
Inventors: |
Clostermann; Friedrich (Hagen,
DT) |
Assignee: |
Trilux-Lenze KG (Neheim-Husten,
DT)
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Family
ID: |
23149468 |
Appl.
No.: |
05/298,199 |
Filed: |
October 17, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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38702 |
May 19, 1970 |
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Current U.S.
Class: |
362/330; 362/333;
362/339 |
Current CPC
Class: |
F21V
5/04 (20130101) |
Current International
Class: |
F21V
5/04 (20060101); F21V 5/00 (20060101); F21v
005/04 () |
Field of
Search: |
;240/16R,106.1,78R,78LD |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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851,867 |
|
Oct 1960 |
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GB |
|
851,217 |
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Oct 1960 |
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GB |
|
Primary Examiner: Peters, Jr.; Joseph F.
Parent Case Text
This is a continuation-in-part of my copending application Ser. No.
38,702 filed May 19, 1970, now abandoned.
Claims
I claim:
1. A cover plate for a lamp having centrically symmetrical light
refractory configurations on one surface thereof wherein said one
surface of the plate is traversed by parallel ribs of V-section, a
first set of a plurality of said ribs running in each of a
longitudinal direction and a direction transverse thereto, and a
second set of said ribs running in two diagonal directions
transverse with respect to each other, said diagonal ribs being
equally spaced whereby the vertex lines defined by the crests of
said second set of ribs divide the plate, when viewed in plan, into
principal and secondary square divisions in a checkerboard pattern,
said first set of ribs being formed in pairs of parallel ridges
having overlapping cross-sections, the cross-sectional shape of the
ribs being extended forming prismatic depressions in the form of
inverted pyramidal depressions between the ribs in both the
principal and secondary square divisions, the inverted pyramidal
depressions in each principal square division comprising a
centrally located octagon with four triangles contiguous to four
sides of the octagon forming a complete principal square, and the
inverted pyramidal depressions in each secondary square comprising
a centrally located square with four pentagons and four triangles
alternately positioned contiguous to the perimeter of the square
forming a complete secondary square; and the opposite surface of
said plate has a boss-like elevation opposite each of said inverted
pyramidal depressions whereby an improved light-scattering effect
is obtained and a lamp located adjacent said opposite surface of
said plate is not visible from the one surface thereof.
2. A cover plate for a lamp according to claim 1 wherein the
distance between the crests of each pair of parallel ridges is
about 0.4142 times the length of a side of a principal square.
3. A cover plate for a lamp according to claim 1 wherein the side
faces of the depressed pyramids are repeatedly broken by pitch
discontinuity lines parallel to the plane of the plate to form
salient and/or reentrant angles.
4. A cover plate for a lamp according to claim 3 wherein the
cross-section of the ribs contains a discontinuity forming a
salient angle, the angle at which the vertex defining the crest of
the ribs being between 80.degree. and 100.degree. and the lower
parts of the sides of the ribs meet at an angle between 110.degree.
and 130.degree..
5. A cover plate for a lamp according to claim 1 wherein the
centrally located octagon and square inverted pyramids are
truncated.
Description
BACKGROUND OF THE INVENTION
This invention relates to a cover plate for a lamp formed on its
surface with centrically symmetrical, light-refractory
configurations.
In illumination technology lamps containing light sources of any
kind are frequently covered with transparent plates provided on
their surfaces with depressions in the form of lenticular, conical
or pyramidal configurations. These configurations are on circular,
square or hexagonal bases. Each of these centrically symmetrical
configurations is intended radially to distribute light uniformly
at theoretically calculable transmission angles.
A tool for the production of such a cover plate must contain an
elevated configuration corresponding with each such depression. The
production of these elevated configurations in the tool involves a
considerable amount of working time.
One problem that arises in the provision of transparent flat covers
or trough-shaped shades for lamps containing fluorescent light
sources is how to obscure a clear view of the light source through
the shade, more particularly how to prevent the elements including
lamps, lamp sockets, and trigger units from being seen. This is not
satisfactorily achieved by using conventional cover plates
containing cone-shaped or lenticular configurations.
The problems contemplated in the present invention arise from this
state of the art.
The tools for the production of the cover plate should be capable
of being mechanically economically produced in such a way that the
elevated configurations corresponding to the required depressions
are all simultaneously formed on the operative side of the tool by
grinding, milling or planing.
SUMMARY OF THE INVENTION
It is, therefore the object of the invention to combine the
centrically symmetrical configurations with other depressions such
that the lamp interior cannot be seen. Generally speaking, it is
intended that it should be possible to direct and distribute the
light flux in vertical planes.
To attain this object the present invention provides a cover plate
for a lamp, formed on its surface with centrically symmetrical
light-refractory configurations, wherein the entire surface of the
plate is traversed in at least three different angular directions
by straight, parallel ribs of simple or modified V-section, of
which the vertex lines defining the crests of the ribs divide the
plate, when viewed in plan, into principal divisions in the form of
hexagon, octagon or decagon depressions with intervening secondary
divisions in the form of smaller triangular depressions and
possibly polygon depressions, and the cross-sectional shape of the
ribs gives rise to the formation of prismatic depressions in the
form of inverted principal and secondary pyramids in the principal
and secondary divisions which form their bases.
The invention also relates to all the features that are herein
claimed, illustrated and described.
When the invention is applied the centrically symmetrical
configuration appears in the form of generally regular
polygon-based inverted pyramids having an even number of corners
with bases in the form of hexagons, octagons, decagons or polygons
having even more corners. The greater the number of corners, the
more will the base in character approach a circle and the more will
the inverted pyramids in the principal divisions assume the optical
properties of inverted cones (conical pyramids).
Nevertheless, it is not necessary to work an elevation separately
for each light refracting configuration into the tools for the
production of the proposed cover plates. The desired configurations
result from the directions and cross-sectional shapes of the ribs
which traverse the entire plate surface, and which can therefore be
produced by grinding, milling or planing. The tools can thus be
economically produced by mechanical means.
The interior of the lamp cannot be seen through the multiplicity of
faceted surfaces (cut-diamond effect). On the one hand the several
inverted pyramidal faces are relatively inclined. In addition, each
side of each inverted pyramid may be broken by one or more
discontinuity lines where the pitch of the side changes. More
particularly the smaller inverted pyramids in the secondary
divisions contribute towards the production of the cut-diamond
effect.
The possibilities of controlled refraction of the light are
inherent in the variability of the parameters of the hexagon,
octagon or decagon based inverted pyramids, i.e. of the refracting
configurations in the principal divisions, such as the size, pitch
and subdivision by discontinuities in pitch of the inverted pyramid
faces.
BRIEF DESCRIPTION OF THE DRAWINGS
Several embodiments of the invention will now be described by way
of example and with reference to the accompanying drawings, in
which:
FIG. 1 is a plan view of a proposed cover plate comprising inverted
octagon in the principal divisions;
FIG. 1A is a cross-sectional view taken along the lines 1A--1A of
FIG. 1;
FIG. 1B is a cross-sectional view taken along the lines 1B--1B of
FIG. 1;
FIG. 2 is a plan view, on a larger scale, of a principal and a
secondary square of FIG. 1;
FIG. 3 is a cross-section of a plate according to FIG. 1; and
FIGS. 4 - 6 are further embodiments of inverted pyramids.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a cover plate for a lamp according to the invention,
the entire surface of which is traversed by ribs in four
directions, namely, longitudinally, transversely perpendicular to
the longitudinal ribs, and diagonally at a 45.degree. angle to both
the longitudinal and transverse ribs.
The shape of the cross-section of the longitudinal and transverse
ribs can be seen in FIG. 1A. 114 is a discontinuity line parallel
to the general plane of the plate dividing the side of each rib
into a lower more steeply pitched part 112 and an upper less
steeply pitched part 113, 111 being the vertex lines defining the
crests of the ribs. This cross-section holds for the ribs extending
in both diagonal directions.
The cross-section shown in FIG. 1B is that of the diagonal ribs.
Pairs of ribs 120 and 120a are provided which partly overlap. 121
and 121a are vertical lines or ridges defining the crests 111 of
the ribs which are spaced a distance 125 apart. 112 and 113
indicate the bottom and upper parts of the sides of the ribs that
are separated by a discontinuity line 114 running parallel to the
plane of the plate.
The ribs are so drawn that in plan a checkboard configuration
comprising squares is formed, namely, principal squares marked 100
and secondary squares marked 200. The distance 125 between
neighboring vertex lines is equal to about (.sqroot. 2 - 1) or
0.4142 times the length of the side of a square.
FIG. 2 illustrates a principal square 100 and a secondary square
200 side by side.
The principal square 100 contains a regular octagon 101 which forms
the base of a regular inverted pyramid with its apex at 102. 103 is
a discontinuity line parallel to the plane of the plate dividing
each side of the inverted pyramid into an upper and a lower face of
different pitch. Four triangles on the octagonal circumference
complete the square. Corner inverted pyramids 104 are
depressed.
The secondary square 200 contains a central inverted pyramid 201 on
a square base. 202 is the apex of the inverted pyramid, 203 is a
discontinuity line corresponding to the discontinuity line 103 on
the octagonal inverted pyramid.
In the secondary square 200 the four sides of the central inverted
pyramid 201 are each adjoined by a pentagon 211 having an apex
marked 212 and a discontinuity line 213.
Four triangles 221 which also form the bases of inverted pyramids
complete the secondary square 200.
FIG. 3 is a cross-section of a plate according to FIG. 1. When such
a plate is produced by the blowing or vacuum process boss-shaped
elevations 310 appear on the back of the plate opposite the
depressions 101. In their totality these elevations by virtue of
their light-scattering effect contribute towards solving the
problem contemplated by the invention, to the extent this relates
to making the interior of the lamp invisible from the outside.
FIG. 4 is a cross-section of another embodiment. 401 are
depressions of pyramids on octagonal bases. 402 and 403 are
discontinuity lines, one forming a salient and the other a
reentrant angle.
In the embodiment according to FIG. 5 the pyramidal depressions 501
are truncated. The surface formed by the truncation is marked
502.
FIG. 6 is a cross-section of a plate according to still another
embodiment.
The embodiments according to the invention can be modified inter
alia as follows:
By the provision of additional discontinuity lines, forming salient
or reentrant angles in the rib cross-sections, the side faces of
the inverted pyramids can be arbitrarily increased in number and
the cut-diamond effect correspondingly enhanced. Instead of
providing flat pyramid faces these may also be slightly curved.
In the illustrated embodiments, the inverted hexagons and octagons
are all regular. However, as an alternative, polygons could be
divided out in which only opposite sides are equal.
The inverted pyramids are so contrived that the apices are located
in the centers of the hexagons or octagons; these may also be
decagons or duodecagons. By suitably varying the cross-sections of
the ribs, inverted pyramids that have eccentric apices can also be
cut out above these polygonal bases.
A cover plate as proposed by the invention may also form part of a
differently designed lamp shade, for instance a dish or
trough-shaped shade.
The invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. The
embodiments are therefore to be considered in all respects as
illustrative and not restrictive.
* * * * *