Note: Descriptions are shown in the official language in which they were submitted.
CA 02638627 2008-08-12
, ~.
Radiating element for light panels and light panel
manufactured using said radiating element
The invention relates to a radiating element for light
panels, which radiating element is in tessera or tile
form, with one of its faces forming the light
radiation-emitting surface, which light radiation is
emitted with an approximately even and constant
distribution over said emitting surface, whereas said
radiating element comprises a light source for sideward
light generation, relative' to the direction
perpendicular or approximately perpendicular to the
emitting surface, and with a 360 angular range about
said source and the central axis perpendicular to the
emitting surface as well as with a predetermined
opening angle for emission of a peak radiation
intensity, particularly a so-called radial emission
generated, for example, by a so-called radial. LED,
which light source is held within the tessera or tile
in a median position relative to the light radiation
emission surface and in an intermediate position
relative to the tessera or tile element and which
tessera or tile element has means for
reflection/scattering the radial light radiation in a
direction incident upon the emission surface. Fig. 1.
Light-emitting elements adapted to emit light
radiation from a surface and with a substantially
constant intensity distribution over said surface are
used as light sources in the manufacture of light
panels. The latter generally consist of a thin box-like
member, with one or two-translucent interiorly backlit
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surfaces. These translucent surfaces have transparent
films or paper sheets laid thereon, with a picture or
message to be publicly displayed. These light panels
are widely used in the fields of advertising, interior
and exterior lighting, road and highway signs and in
other fields.
Various light-emitting elements for light panels
are known in the art:
Light panels with fluorescent or neon tubes in
which the tubes are placed behind the panel emitting-
surface and illuminate the front of the panel emitting-
surface.
Light panels with a plate-like scattering element
in which the light radiation sources illuminate the
scattering element from one or more delimiting sides of
the scattering element and scattering occurs in the
direction of the front surface of said scattering
element, which becomes the light radiation-emitting
surface. Here, the light sources may be fluorescent
tubes, incandescent lamps and LEDs.
Light panels with front LEDs,. in which LEDs emit
light radiation from an emitting head directed towards
the user, i.e. perpendicular or approximately
perpendicular to the emitting surface. In this case,
the LEDs are oriented to the front and lie on the
bottom of the panel, each forming a unit point of
minimum size, i.e. some sort of pixel, of a luminous
picture composed of a number of said LEDs.
All the above systems can provide light panels,
but all the above systems suffer from drawbacks
deriving from their complex construction, inadequately
homogeneous light intensity along the emitting surface,
short life and difficult manufacture using industrial
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i
processes.
The radiating light-emitting element described
initially, i.e. as defined by the preamble of claim 1,
also suffers from considerable drawbacks, mainly in
that it is always comparatively expensive, has a
complex construction and does not optimize scattering
of the light intensity radiated towards the emitting
surface.
Therefore, the invention is based on the problem
of providing a light-emitting radiating element for
light panels, that has a simple and inexpensive
construction and a smaller weight, requires less
maintenance and whose maintenance is simpler and less
time-consuming, while at least preserving, and possibly
improving performance in terms of light emitted from
the emitting surface.
The invention fulfills the above purpose by
providing a radiating element for light panels as
described hereinbefore, and wherein the
reflection/scattering means form the tessera or tile
element and are formed of a half-shell shaped plate
with a polygonal plan shape and with a concave
reflection/scattering side facing towards the emitting
surface and a convex side opposite said emitting
surface, the central area of the shell having an
opening for receiving the light source which has the
radiating head within the depression of the concave
side and at a focal point of said concave surface, so
that the light radiation emitted from the emitting head
of the light source in the sideward, i.e. radial
direction, relative to the central axis of symmetry of
the reflection/scattering means, is reflected/scattered
in a predetermined percentage in a direction incident
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upon an emitting surface oriented along a plane
transverse, preferably perpendicular to the central
axis of symmetry of the reflection/scattering means.
The convex surface may be of reflective, mirror-
like type or of scattering, i.e. white type.
The half shell element that forms the tile or
tessera may have ,any plan shape, e.g. a square or
triangular shape or other regular or irregular
polygonal shapes.
Advantageously, the front concave surface facing
towards the emitting side of the half-shell plate
and/or the rear convex surface have a paraboloidal
curvature.
The plate or sheet that forms the
reflection/scattering means due to its concave shape,
is advantageously, but without limitation, made of a
plastic material, preferably a heat deformable plastic
material.
The plate of which the reflection/scattering means
are made may be relatively thin, with typical
thicknesses for vacuum and hot forming (i.e.
thermoforming) processes. These processes are known and
widely used, for example in the fabrication of food-
grade plastic containers or shaped, expanded fruit
trays.
Concerning the light source, this advantageously
consists of a radial or edge-emitting LED with 3600
light pattern as described above in greater detail.
According to a further itnprovement, the concave
side of the half-shell reflection/scattering means is
closed by a transparent or translucent element with
coupling means for connecting the peripheral edge of
said closing element to the peripheral edge of the
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reflection/scattering means.
Preferably, the transparent closing element has
the same plan shape as the reflection/scattering means
and is at least approximately congruent with the plan
shape of these means.
These mutual _peripheral fastening means, with
either continuous or discontinuous extensions, may be
coupling means engaging with complementarily shaped end
portions of the peripheral edge of both the
reflection/scattering means and the closing element,
such as clips or the like that are designed to engage
with folded peripheral edges or peripheral edge
segments that form peripheral coupling grooves along
the peripheral edges of the reflection/scattering means
and the closing element and are open at respective
opposed sides.
Advantageously, the covering element or closing
element has a surface area with lower transmission
coefficient, i.e. lower transparence, in a central
portion coincident or coaxial with the light source
head, as compared with the remaining peripheral
portion, which surface area attenuates the intensity of
the light radiation emitted at the light source head,'
at least approximately to the same level as the
intensity of the light radiation emitted through the
surface area of the transparent closing element with
higher transmission coefficient, i.e. surrounding such
central portion. Thus, in addition to the advantage of
closing the light source compartment to the external
atmosphere and of providing a tessera or tile that is
externally closed and has a very low weight and very
low material, fabrication and assembly costs, the light
intensity is radiated through said closing surface with
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optimized homogeneity, whereby the emitted light
radiation is substantially constant throughout the
emitting surface, i.e. the surface of the closing
element.
According to an advantageous embodiment, this
central surface portion with the lower light
transmission coeff-icient is a, depressed central
portion, i.e. a central depression of the surface of
the closing element and the bottom of this depression
undergoes a treatment for reducing the transmission
coefficient.
The closing element is also advantageously formed
by vacuum and hot forming processes from a thin plate
of transparent plastic material, as mentioned
concerning the reflection/scattering means.
According to yet another characteristic, the light
source, i.e. the radial or edge-emitting LED is
directly mounted to the header of a printed circuit
board, typically made of glass epoxy, which header also
bears the tracks of the printed circuit board that
forms the power supply circuit for said source and
possibly some of the circuit components of a power
supply or power regulation circuit for said source, the
light source being provided on one side of said header
and said header being fixed or fixable to half-shell
reflection/scattering means whereas, in the mounted
condition, said header extends tangent to the convex
side of the reflection/scattering means in the area of
the central light source receptacle and said light
source projects cantilever-wise out of the concave side
of the reflection/scattering means in the focus of the
paraboloid.
According to yet another advantageous
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characteristic of the invention, the LED is attached to
a metal plate, preferably made of aluminum, allowing
heat dissipation and fixation of the light-emitting
radiating element to a load bearing structure, which
aluminum plate is placed tangent or parallel to a
position tangent to the convex side of the
reflection/scattering means in the area of the central
light source receptacle, and said light source projects
cantilever-wise out of the concave side of the
reflection/scattering means in the area of the focus of
the paraboloid, whereas said reflection/scattering
means are or can be attached to said metal plate.
Here, the header/s of the printed circuit board of
a power supply circuit or a power regulating circuit
for said light source are also mounted to said metal
plate, e.g. in a slightly offset position, in the area
peripherally surrounding the light source, and in which
the convex side of the reflection/scattering means are
spaced from the metal plate.
The metal plate is substantially coaxial or
concentric with the plan shape of the
reflection/scattering means and does not project out
of the peripheral sides of said means.
The size of the radiation element depends on the
type of light source, particularly LED, being used and
on the -light intensity to be obtained through the
emitting surface, with the side or diameter ranging
from 5 cm to 30 am.
In one alternative embodiment, the
reflection/scattering means are formed of a thin metal
sheet, such as aluminum sheet or the like, one of whose
sides, i.e. the one designed to form the concave side,
is treated to become reflective, coated with a layer of
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material providing a scattering effect, e.g. with white
paint, and which sheet is shaped by molding.
In accordance with an additional variant
construction of the invention, two or more radiating
elements as described above are integrated in one
element, the half-shell reflection/scattering means for
two or more light sources being formed from a single
sheet of material that is shaped to form two or more
half-shells in side-by-side relationship on one or more
sides.
Each of the reflection/scattering means integrated
in the multiple radiation element is formed according
to one or more of the features as described above with
reference to the single radiating element.
Here, a corresponding multiple closing element is
provided, composed of an array of si.de-by-side single
closing elements, each having a central portion with a
lower light transmission coefficient, coincident with
the light source of the corresponding
reflection/scattering means of the array of said means
in the multiple radiating element.
The multiple closing element also can have one or
more of the features as described above with reference
to the closing element of the single radiating element..
Concerning the means for fixing the multiple
covering element to the corresponding array of
reflection/scattering means, the fixation means may be
substantially identical to those of the single
radiating element, and are located at least along the
coincident peripheral edges of the multiple closing
element and the array of reflection/scattering means.
According to yet another characteristic of the
invention, an array of single or multiple radiating
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elements is provided, in such combination as to cover
various shapes and sizes of the surfaces to be
illuminated and particularly an array of radiating
elements is provided that has one or more single
radiating elements, one or more double radiating
elements, one or more triple radiating elements, one or
more quadruple radiating elements, and one or more
sextuple radiating elements, or a combination of such
single or multiple radiating elements.
Here, the single radiating elements advantageously
have a square plan shape.
The multiple radiating element advantageously
improves the efficiency of the construction, to further
reduce costs, weight, as well as construction and
assembly complexity.
Particularly, according to a first characteristic,
the light sources may be mounted to a common metal
support sheet or the like, each being located
coincident with the receptacle of the corresponding
reflection/scattering means and printed board circuits
may be provided that are formed of an element shared by
two or more light sources.
The combination of single radiating elements into
multiple radiating elements provides various
advantages, namely:
-- easier and less costly assembly of the radiating
elements in the light panel;
- easier and less costly power supply to the light
sources. Particularly, a combination of six single
radiating elements having six 2 Watt LEDs allows the
sextuple radiating elements to be powered by a 24 Volt
direct current source and, by particular arrangements,
the other single or multiple elements can be also
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powered with a predetermined reference voltage.
- less costly assembly of the multiple radiating
elements and better storage conditions before assembly
into a light panel.
According to yet another characteristic of the
invention, the transparent covering element may have
stiffening ribs arranged in a predetermined pattern
over the surface of said covering element.
Also, according to a further characteristic, the
multiple covering element has a plurality of projecting
spacers for a transparent or translucent plate of a
light panel, which is illuminated by a multiple
radiating element of the above type.
The spacer elements are optional and their
provision depends on the width dimension of the plate,
which can be very large, and possibly cause buckling of
the plate under its own weight.
These projections may be other than the ribs or at
least partly formed of the above stiffening ribs.
The invention also relates to a light panel having
at least one bearing frame for supporting a plurality
of light emitting means mounted to the back of at least
one translucent or transparent plate, which bears or
supports graphical information formed by a combination
of transparent and/or translucent surfaces having
different colors and/or light transmission
coefficients, the light emitting means including,
according to the present invention, one or more single
or multiple radiating elements as described above.
The invention relates to further characteristics
which form the subject of the dependent claims.
The characteristics of the invention and the
advantages deriving therefrom will appear more clearly
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from the following description of a few non-limiting
embodiments which are illustrated in the accompanying
drawings, in which:
Fig. 1 is a cross sectional view of a first
embodiment of a single radiating element of the present
invention.
Fig. 2 is a cr.ass sectional view of a light panel
comprising a plurality of radiating elements of Figure
1.
Figure 3 shows a covering element for a multiple
radiating element.
Figs. 4A to 4D show different schematic
configurations of multiple radiating elements composed
of two, three, four and six single radiating elements
having a square plan shape respectively.
Fig. 5 is a top plan view of the array of sextuple
radiating element acting as light emitting means of a
large light panel.
Figures 6A and 6B show two multiple radiating
elements composed of four and eight single triangular
radiating elements respectively.
Figures 7 to 9 show a single radiating element
according to three different variant embodiments,
differentiated in that they have no annular leng
associated to the light source, or an annular lens with
a frustoconical section or an annular square lens with
a square section respectively.
Figures 10 to 12 and 13A to 13B are various views
i.e., respectively, a cross sectional view as taken
along line A of Figure 11, a top plan view and a
lateral long-side view and a perspective view in the
assembled and exploded conditions respectively, of a
multiple radiating element composed of six single
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radiating elements having a square plan shape arranged
on two side-by-side rows of three single radiating
elements each.
Figure 14 shows an enlarged, partially sectional
detail of the light source-associated portion of the
radiating element.
Figure 15 shows an alternative embodiment of a
multiple radiating element and/or a light panel having
light sources capable of side or radial light radiation
emission over a 360 range.
Fig. 16 is a plan view of an exemplary light panel
composed of elements having 6, 3, 2 and 1 base
radiating elements.
Referring to Figure 1, a single radiating element
1 for illuminating light panels is composed of half-
shell reflection/scattering means 2 having at least one
concave front surface 202. The half-shell may have any
shape whatever, such as a circular, square, triangular
shape or a polygonal shape with a greater number of
angles, the polygonal shapes being preferably, but
without limitation, regular and equilateral.
The concave side 202 of the half-shell is
rotationally symmetrical with respect to the central
axis perpendicular to the plan shape of the half-shell
and curvature front side 202 of the half-shell is of
paraboloidal shape, which is rotationally symmetrical
with respect to the same central perpendicular axis of
rotational symmetry of the plan shape of the half-
shell.
The front side has such a curvature has to form a
reflection/scattering surface to reflect/scatter the
light radiation coming in a direction radial to the
central axis of symmetry of the half-shell and hence of
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the concave front side 202, so that the light rays
having said radial direction and an inclination within
a predetermined opening angle about the radial axis
associated with said central axis of symmetry - which
might be defined as an opening in the azimuth direction
- are reflected/scattered in a direction incident upon
a plane oriented tkansverse, preferably perpendicular
to the axis of symmetry of the half-shell and the front
side 202 thereof.
The half-shell has a central receptacle 102 at its
central portion, arhich is coaxial with the central axis
of symmetry of the concave side 202, for receiving the
socket 205 of a light source 5, whose light radiation
emitting head 105 projects into the space defined by
the concave front side 202. The light source 5 is an
edge-emitting source operating over a 360 range, i.e.
a light source that emits light radiation with an
intensity distribution in which intensity is higher or
concentrated in a direction radial to a central axis
oriented in a desired light radiation emitting
direction, with a predetermined opening in the plane
containing said axis and with an angular extension
corresponding to a round angle, i.e. 360 . In the
present Figure 1, light radiation is emitted at the
head 105, said light radiation distribution being
coaxial with the central axis of symmetry of the
reflection/scattering means and particularly of the
concave surface 202.
According to a particular construction
characteristic of the embodiment as shown in Figure 1,
the reflection/scattering means are formed of a thin
sheet that is shaped to have a concave shape on the
front face 202 and a corresponding convex shape on the
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opposite face. The face, i.e. the concave front side
202, undergoes such a treatment as to reach a desired
reflection/scattering coefficient, which can occur in
various manners, e.g. through the application of a
reflective white paint and/or buffing or other means.
Advantageously, the plate that forms the
reflection/scattering means 2 is made of thermoformable
plastic material and preferably has such a thickness
as to allow shaping by a simple vacuum and hot forming
process, also known as thermoforming. Such forming
process is known to be used, for example, with food-
grade packaging containers or the else, expanded fruit
trays or the like.
Otherwise, the plate that forms the
]5 reflection/scattering means 2 is made of metal, such as
aluminum. In this case, thickness is selected in view
of allowing the plate to be shaped by molding, and
ensuring that the half-shell has some structural
stability.
Composite material plates can be obviously used,
such as multilayer plates having such composition as to
afford structural stability, formability and low weight
and cost.
The reflection/scattering means 2 provided by the
concavo/convex half-shell have the concave side closed
by a covering element 4 of transparent material which
forms the light radiation emitting surface, the light
radiation emitted by the source 5 radial to the central
axis of symmetry being deflected by the concave surface
202 in a direction incident upon said covering element.
The covering element 4 is made of transparent and/or
translucent material and particularly of transparent or
translucent plastic material. As mentioned above with
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reference to the reflection/scattering means 2, the
covering element is formed of a thin thermoformable
plate.
The covering element 4 can be fixed to the half-
shell acting as reflection/scattering means to form a
box-like radiating element containing the emission head
of the light source 5 in a predetermined position
relative to the concave surface 202 of the half-shell.
Particularly, said covering element has a plan shape
substantially identical to the plan shape of the half-
shell acting as reflection/scattering means and is at
least approximately congruent therewith. The closing or
covering element 4 and the half-shell that acts as
reflection/scattering means 2 are mutually fixed along
the peripheral edges of said two parts that have
matching peripheral mutual fixation flanges 502.
Such fixation can occur either continuously or
discontinuously all along the flanges, by
chemical/physical bonding, such as welding, gluing or
the like or using detachable fastening means, such as
interloc)cing means, or mutual clamping means, such as
screws and bolts or possibly by clipping.
In the latter exemplary embodiment as shown in
Figure 1, the peripheral flanges 502 of the half-shell
acting as reflection/scattering means 2 and the
covering element are formed with a peripheral channel-
or groove-like section and are open on opposite sides,
thereby forming two opposite coupling grooves for C-
shaped clips 3. These clips may be discontinuous
elements arranged along the peripheral extension of the
two parts to be fixed or a C-shaped continuous band may
be provided.
In both variants, the clips may be either
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elastically deformed for snap engagement with the
flanges 502 or the clips may be inelastical.ly deformed
and then applied by shaping them around the flanges 502
to clamp them together.
Still concerning the closing or covering element
4, this element has a central portion, i.e. a portion
coincident and/or possibly coaxial, with the emitting
head 105 of the light source 5, which portion 402 is
formed with a lower light radiation transmission
coefficient as compared with the rest of the covering
element 4. This arrangement has the purpose of
attenuating a light radiation intensity peak towards
the central axis of symmetry and generates
nonhomogeneous distribution of the light intensity
radiated from the surface of the covering or closing
element 4.
According to this embodiment, this portion treated
for radiation intensity attenuation is a central
depression 302 concentric and possibly coaxial with the
head 105 of the light source 5, whose bottom 402 and/or
possibly the lateral parts of which depression 302 are
treated as described above.
The light source 5 is supported by a base plate.
Such plate may be the header of the printed circui=t
board that forms the power supply circuit and/or the
power regulation circuit or at least part of said power
supply and/or power regulation circuits of the light
source 5, wherefore such header also bears, in this
case, at least some of the circuit components. The
header may be further supported by a base plate that
also acts as a heat sink.
The plate may also be a cooling plate, such as a
plate made of metal, aluminum or any other material
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with a high heat transmission coefficient, which plate
has the function of dissipating the heat generated by
the light source and which plate may in turn have,
alongside the light source 5, one or more printed
circuit board headers for the power supply and/or power
regulation devices or for part of said devices or
circuits.
Figure 1 shows the above solution, the source 5
and the header 7 of the power supply or power
regulation circuit or part of said circuits being
supported by a heat dissipation plate 6.
The heat dissipation plate 6 and/or the header
also support the reflection/scattering means 2 and the
covering element 4 that are or can be fixed, preferably
in a detachable manner, to the source 5 and/or the
header 7 and/or the heat dissipation plate 6.
Depending on the construction variant selected
from the two above options, the header 7 and/or the
heat dissipation plate 6 also act as a socket for
connection of the single radiating element 1 to a
bearing structure of a device in which such radiating
element 1 is used or located, like the light panel of
Figure 2 as described in greater detail below.
Referring to Figures 7 to 9, a variant embodiment
is shown in which the reflection/scattering means 2 are
not formed as a half-shell with a relatively thin wall
and hence with a concavo-convex shape, but as a plate
having one concave depression on one side, acting as a
reflection/scattering surface 202.
The figures also show, on the right side, the
intensity distribution pattern of the radiation emitted
by the light source in various conditions and variants,
as described in greater detail below.
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In Figure 7, the light source has no concentration
lens and the opening angle of radiation in the radial
direction causes part of the radiation to fall out of
the concave, paraboidal reflection/scattering surface
202 and be lost and excluded from the overall radiation
intensity emitted through the emitting surface, i.e.
the covering element or the element or surface to be
backlit, designated by numeral 9 in Figures 7 to 9.
In Figure 8, the light source is provided in
combination with an annular lens 10 having a right
trapezoidal cross section, and a frustoconical cross
section along the external long diameter. The light
source head 105 is held within the central hole of the
annular lens 10. This arrangement reduces the opening
angle of radiation in the radial direction, thereby
focusing a higher light intensity on the
reflection/scattering surface 202.
The same effect is obtained using an annular lens
of rectangular or square cross section, as shown in
Figure 9 and designated by numeral 11. As can be seen
from the values on the axes, the solution of Figure 9
with the lens of square or rectangular cross section is
an intermediate solution allowing recovery of a small
part of the radiation emitted by the light source in
the upper margin area of the opening cone, whereas the
solution of Figgure 8 with the frustoconical lens 10
allows recovery of a considerable amount of radiation,
by deflecting it onto the concave surface 202, and
focuses the radially emitted radiation into an opening
cone of smaller angular width, i.e. a smaller opening
angle.
It can be noted, with reference to Figure 13A,
that the annular lenses 10, irrespective of their
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shape, are separate parts designed to be coaxially
fixed to the light source 5, i.s. to the part of the
latter from which the light radiation is emitted, which
is designated by numeral 105 in Figure 14.
Particularly, these parts are detachably fixed, such as
by interlocking arrangements or other known detachable
mechanical fixatioxi, and the annular lens 10 is
especially fixed against the reflective surface 202 all
around the through hole for the radiating head 105 of
the light source 5.
According to another characteristic, the side of
the annular lens 10 that is designed to contact, be
fixed or at least face towards the area of the
reflective surface all around the through hole for the
light source 5 may be treated to become reflective.
Particularly, such side of the annular lens 10 i-s
covered with a white adhesive film and/or subjected to
pad printing or coated with a layer of white paint.
Obviously, said surface of the annular lens 10 may
undergo any alternative treatment for providing said
white surface on the side facing towards the inside of
the lens.
Referring to Figure 2, the single radiating
element 1 may be used for manufacturing light panels,
i.e. panels in which a message, an image or else are
emphasized by backlighting. Here, the panel may have
various constructions and the light-emitting radiating
element 1 may be used in combination with various
construction features.
A very simple light panel embodiment is shown in
Figure 1. In this case, the panel frame has a box shape
and is composed of a rear container or tray 12 having a
bottom wall 112 and side walls 212. A plurality of
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radiating elements 1 of the present invention are
accommodated in this container or tray in side-by-side
relationship, in both height and width directions of
the tray, and are fixed in position using detachable
fastener elements 13, such as screws, bolts, or other
means, such as interlocking of their plates 6 or 7 to
the bottom side 112 of said container or tray 12 and
with the concave side 202 of the refleation/scattering
means 2 and the covering element 4 facing towards the
open side of said container or tray 12. (FIG. 1 and
FIG. 2) .
The plan size of the tray or container 12, i.e.
the plan size of the surface to be illuminated and the
plan shape are exact multiples of the size of the
radiating element 1. The front side of the light panel
is equipped with a plate of transparent or translucent
material 14, in direct contact with the front side,
i.e. the covering elements of the array of radiating
elements 1, or somewhat spaced therefrom by means of
spacer elements. The plate 14 bears a communication
message drawn directly thereon or on a support separate
from the plate 14. A cover 15 with a window 115 closes
the front of the light panel to overlie a peripheral
strip of the plate 14 in a frame-like fashion, and
possibly has side walls 215 overlying the side walls
212 of the tray or container part 12.
The tray or container part 12 has elements 16 at
its back for fixation to a support, such as a wall, a
post or other means. Furthermore, the container or tray
12 has a tight opening for receiving power leads 17.
These leads may be connected to any power source, power
being transformed by a power supply unit 18. The
latter may be located wholly or partly outside or
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inside the panel.
Figures 3 to 14 show an improved construction,
providing integration of two or more single radiating
elements, i.e. radiating elements having each at least
one light source, in a multiple radiating element, i.e.
a double, triple, quadruple or sextuple element. An
array of such multiple radiating elements may be also
provided, to cover various areas of light panels,
possibly having different plan shapes.
Figures 4A to 4D show multiple panels composed of
two, three, four, five and six single radiating
elements having a square plan shape.
Figure 5 shows a plan shape of an exemplary light
panel in which the translucent plate 14 is illuminated
by a plurality of multiple radiating elements, each
composed of six single radiating elements 1. The figure
shows the tray or container 12 in which six multiple
radiating elements are accommodated.
Figures 6A and 6B show multiple radiating elements
composed of a plurality of single triangular radiating
elements, which are combined together to form larger
triangular emitting surfaces. The figures are intended
to be schematic do not provide construction details.
Arrays may be further provided with single and
multiple radiating elements having different plan
shapes. For instance, such arrays of single and
multiple radiating elements may include single
radiating elements of isosceles triangular and square
plan shapes, each triangular radiating element being
identical to the diagonal half of the square element,
whereas the multiple radiating elements are composed of
one or more single square radiating elements and one or
more single triangular radiating elements or
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combinations of one or more of said square and
triangular radiating elements.
Figures 3 and 10 to 14 show in greater detail a
construction embodiment of the reflection/scattering
means for a multiple radiating element integrating six
single radiating elements.
The reflectiori/seattering means designated by
numeral 20 are formed of a half-shell which is shaped
to include six depressions in side-by-side relationship
in one or both directions of extension of such half-
shell, each of which forms the convex side 202 of one
reflection/scattering means 2 for a single radiating
element. Advantageously, the reflection/scattering
means 20 of the multiple radiating element are also
formed. as a relatively thin plate made of plastic or
another material as described above concerning the
single radiating elements of Figure 1. The convex
surface 202 also has all the characteristics indicated
therefor in the description of the single radiating
element and, since the latter is a square radiating
element, its concave paraboidal surface is formed of
four wedges joined together along the diagonals of the
square plan shape.
Therefore, the plate has a single-piece
construction, whereas the central portion, coaxial with
the central axis of the plan shape (still as described
above for the single radiating element), includes the
receptacle of the light source 5 which is also of the
radial or edge-emitting type, relative to the central
axis of symmetry. In the variant of Figures 10 to 14,
an annular lens of frustoconi.cal section 11 as
described with reference to Figure 8 is provided around
the emitting head 105 of each of the light sources.
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Nonetheless, such lens can be also omitted, as
mentioned above concerning the single radiating
element.
Still with reference to Figures 10 to 14, as
particularly shown from Figure 13B, the construction of
the multiple radiating element 20, which integrates in
this case six single radiating elements, but may be
provided in other patterns with more or less than six
elements, also allows one-piece construction of the
metal heat dissipation plate designated by numeral 6
and provides improved efficiency, with one header 7
having the power supply circuits or parts thereof for
two or more LEDs or all the LEDs of the multiple
radiating element.
In this example, the header 7 is formed as an
elongate element having such an extension as to overlie
three receptacles 102 of the three light sources 5 of
three adjacent single radiating elements aligned along
a longitudinal direction of the multiple radiating
element. Particularly, as shown in Figure 14, each LED
adheres to the heat dissipation plate 6 by its base
205, whereas the header 7 has a through hole coincident
with the emitting head 105 of the LED and with the
receptacle 102 in the corresponding
reflection/scattering means through which hole the
emitting. head 105 projects from the side of the header
7 opposite the one facing towards the heat dissipating
plate 6. Thus, the base 205 of the LED 5 is interposed
between the header 7 and the plate 6.
During assembly, the LEDs are mounted to the
header 7 by connecting the LED contacts to the
corresponding tracks and, in the position as shown in
Figure 14, in which the socket 205 adheres to the rear
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side of the header (considering the direction of
illumination of the radiating element) and the emitting
head 105 projects out of the front side of the header
7. The assembly of the header 7 and the three LEDs 5 is
formed separately as a construction unit to be later
mounted to the heat dissipation plate 6 with the
multiple reflection/scattering means 20 being
associated therewith by fitting the heads of the LEDs 5
in the apertures 102 of the concave portions 202.
According to yet another characteristic, the
header may be selected to obtain 2 and 1 LED elements.
The frustoconical annular lenses, with the head
105 of the light source 5 held therein, are associated
with the receptacles 102.
The embodiment of Figures 11 to 14 is a
construction variant of the embodiment of the previous
figures and of the single radiating element, because it
does not have a covering or closing element like the
closing or covering element 4 of the single radiating
element.
In this case, the radiation emitted by the LED in
the direction of the central axis of symmetry is
attenuated by an attenuation element with a
predetermined transmission coefficient which is
integrated, or is or can be fixed, possibly in a
detachable manner, to the annular lens 11.
Particularly, in the embodiment of Figures 11 to 14,
this attenuating element 21 is a disk of transparent or
translucent material engaging in the central hole of
the annular lens 11. The disk lies over the emitting
head on the front side of the radiating element.
Otherwise, the disk may have a larger diameter and
overlie the front end side of the lens 11 and have a
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thicker portion in the central portion which is adapted
for interlocking engagement in the central hole of the
annular lens 11.
Nevertheless, the multiple radiating element may
be similar to the single radiating element of Figure 1,
in that it also has a covering or closing element 40,
which covering or -closing element 40 is a multiple
element integrating two or more single closing or
covering elements in one part.
The multiple closing or covering element
preferably has a plan shape corresponding to the plan
shape of the multiple reflection/scattering means 20
and is formed of single covering or closing elements
whose shape and size correspond to those of the single
reflection/scattering means 2 integrated in the
multiple reflection/scattering means and are located in
a position coincident, centered and coaxial therewith.
The multiple covering or closing element 40 has a
portion 420 coincident with each of the light sources,
with a predetermined transmission coefficient for
attenuating the emission of said sources in the
direction of the central axis of symmetry of each
concave ref].ection/scattering surface of the single
reflection/scattering means that form the multiple
radiating element.
This portion 420 may also consist of a depression
320 as described in the single radiating element
embodiment.
Concerning the closing and covering element 40 of
the multiple radiating element, means may be provided
for fixation thereof to the multiple
reflection/scattering means that are formed in the same
manner as those of the single radiating element,
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CA 02638627 2008-08-12
reference being made here to the description thereof.
Also, the multiple covering element 40 may be also
constructed like the covering element 4 for a single
radiating el.ement, i.e. a thin plate or sheet of
transparent or translucent plastic material, which is
shaped by molding. Once again, the sheet or plate have
such thicknesses and materials as to preferably allow
vacuum and hot forming.
In Figure 3, the covering element integrates four
single covering elements, whereas the multiple covering
element extended -to six single covering elements is
indicated by dashed lines.
Still in Figure 3, the multiple covering element
may have stiffening ribs, designated by numeral 41,
coincident with the peripheral areas of the concave
surfaces 202 of the multiple reflection/scattering
means 20.
In addition to or instead of such stiffening ribs,
the multiple covering element 40 may have projecting
spacers 42 for spacing a translucent or transparent
plate of a light panel like the one designated by
numeral 14 in Figure 2.
In the example of Figure 3, the multiple covering
element 40 is formed with a eoncavo/convex shape, i.e'.
as a substantially non-planar half-shell like in the
example of Figure 1. This variant is applicable to the
single covering element 4 of Figure 1 and vice versa.
Concerning the example of Figure 15, in a basic
embodiment of the present invention a single or
multiple radiating element is provided which has one
radial or edge-wise light emitting source as defined in
the present invention. Obviously, in this case, in
order to ensure uniform intensity of the light emitted
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CA 02638627 2008-08-12
through the emitting surface 9 or the surface of a
plate like the one designated by numeral 14 in Figure
2, a predetermined position has to be set between the
distance of the emitting head 105 from the emitting
surface 9 and the lateral distance of the individual
heads 105 of two or more LEDs or light sources from
each other.
Here, an optimized, though non optimal solution
was found to be provided by a relative arrangement of
the LEDs or light sources 5, particularly the heads
thereof, considered as point light sources, and a
distance of these heads from the emitting surface, that
fulfill the following condition:
Angles A < arctg (2x/D)
Where :
D is the distance between the points that define
the position of the emitting heads 105 of two adjacent
light sources;
x is the distance of the plane containing said
points that define the position of the emitting heads
of the light sources from the emitting surface and
particularly from the facing side of a plate that acts
as an emitting surface.
Therefore, in accordance with the above, 'a
construction may be provided for single or multiple
radiating elements, with a light source supporting
plate, which plate has a radial or edge-wise light
emitting source at its center (as defined herein), the
plate having such a size that the radi.us of said plate
or of a circle inscribed in the plan shape of said
plate or inscribing the plan shape of said plate is
equal to D/2, whereas a covering surface is associated
with the plate at such a distance therefrom as to
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CA 02638627 2008-08-12
fulfill the above condition.
In one embodiment, the LED supporting plate may be
the heat dissipating plate 6 and/or the header 7
according to one or more of the variants proposed for
one or more of the above embodiments, whereas the
emitting surface may be formed as a concavo-convex
dome, in which the concave side.faces towards the
supporting plate 6 thereby forming a closed
compartment. This arrangement also provides a box-lilce
radiating element. Once again, means may be provided
for detachable or permanent fixation of the dome-shaped
element to the supporting plate, which may be as
described above for one or more of the previous
embodiments.
It will be appreciated that multiple radiant
elements may be also provided that integrate two or
more single radiating elements having construction
characteristics of one or more of the previous
embodiments of multiple radiating elements.
Particularly, a multiple radiating element may
include at least two light sources mounted to a
supporting plate in a central position relative to two
adjacent areas of said plate, each of which areas has
such a size that the radius of said area, i.e. of 'a
circle inscribed in the plan shape of said area or
inscribing the plan shape of said area is equal to D/2.
Concerning the emitting surface, this can be
associated to the plate or the plate may be equipped
with spacer elements for spacing an emitting surface,
or be provided in combination with a structure having
such spacer elements, the distance of the emitting
surface being equal to a distance x that fulfills the
above condition.
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Finally, the embodiment of Figure 15 allows a very
simple construction of the light panels with a
minimized number of parts. Particularly, in a panel as
shown in Figures 2 and/or 5, the heat dissipation plate
may be omitted and the LEDs 5 may be mounted to headers
7 similar to those of the example of Figure 13B, which
headers 7 are directly fixed to the bottom of the tray
12, whereas the tray is equipped with spacer elements
on which the transparent or translucent plate 14 is
designed to rest, which are in such position as to
provide a distance x from the plane containing the
points that define the light radiation source positions
of the light sources.
A number of variant embodiments may be obviously
provided, concerning the construction of the headers
and/or the LED supporting plate.
Therefore, a panel as disclosed above has a
support element for one or more plates, each carrying
one or more LEDs in mutually offset positions, and with
the emitting heads contained in a common plane and a
transparent or translucent plate, which is provided at
a predetermined distance from said emitting head
containing plane, the distance D between the emitting
heads and the distance x of the emitting heads from the
transparent or translucent plate being determined by
the following condition:
Angles A < arctg (2x/D).
Finally, concerning the radiating element of
Figure 15, lenses like those of Figures 9 or 10 and/or
attenuation elements like those 21 of Figs. 11 and 14
and/or like those designated by numerals 402, 302 in
Figure 1 may be also associated with the head of the
light sources 5.
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~= . .
Figure 16 shows an exemplary light panel in which
the radiating element is composed of a plurality of
elements, each having a different number of square base
radiating elements. Figure 16 shows one of the many
possible examples and is only intended for illustration
purposes. This example provides a combination of
radiating elements integrating six,.three, two and one
base radiating elements respectively. The separation
of the various multiple radiating elements is
graphically indicated by a spacing, whereas each
multiple radiating element is shown as comprising the
corresponding amount of base radiating elements in
direct contact with each other. The figure also shows
the peripheral edge of the base casing which is part of
the panel frame and receives these radiating elements.
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