|Title of Invention
GLASS SUBSTRATE PROVIDED WITH RAISED GLASS ELEMENTS
|A glass substrate comprising raised glass elements (20) placed over part of its area, characterized in that the glass elements (20) are intrinsically incorporated into the substrate.
|GLASS SUBSTRATE PROVIDED WITH RAISED GLASS ELEMENTS
The invention relates to a glass substrate provided
with raised glass elements placed over part of its
Although not limited to such an application, the
invention will be more particularly described in the
case of glass substrates with reference to the
production of a flat emissive screen, and more
precisely a plasma screen. Other uses, such as for FED
screens or plane lamps, may also be envisioned. The
expression "plane lamp" should be understood as
encompassing lamps intended for the manufacture of
portable computers and lamps of larger dimensions for
architectural applications, such as for the production
of advertising panels or of partitions, for example in
offices, whatever the technology of these lamps.
A plasma screen is essentially composed of two plane
glass substrates. Deposited on at least one of the
substrates are one or more electrode arrays, a layer of
a dielectric material and layers consisting of
phosphors corresponding, for example, to the colors
green, red and blue. Before being joined together, the
glass substrates also receive barriers, the functions
of which are to form a multitude of cells, which
isolate the phosphors from one another, and to keep the
two glass substrates a certain distance apart.
The barriers, also called ribs, are produced
independently of the glass substrates and attached to
the substrate. The ribs are obtained by depositing a
glass frit joined to one of the substrates by a process
which has, however, slow steps, such as sandblasting
and screen printing, and complex and expensive steps
requiring, in particular, the recycling of the dust
generated during the sandblasting step, which is not
without creating a few pollution problems.
Moreover, it has been noticed that the phosphors suffer
functional degradation due to the deposition on the
ribs of impurities generated during the process for
obtaining the ribs.
Furthermore, to ensure proper operation as regards the
ignition voltages of the electrodes, it is necessary to
cover the electrodes with a dielectric, the deposition
of which constitutes an additional step, which goes
counter to the ever desired aim of improving the
The object of the invention is therefore to propose a
glass substrate provided with raised glass elements so
as especially to constitute ribs which do not have the
drawbacks of the prior art and allow cost savings to be
made in the manufacture of products using such a
According to the invention, the glass substrate
comprising raised glass elements over part of its area
is characterized in that said glass elements are
intrinsically incorporated into the substrate.
Preferably, the body of the substrate has two opposed
parallel faces, the elements being incorporated into at
least one of the two faces.
According to one feature, the glass elements lie along
at least one line approximately parallel to one side of
the substrate; they may form at least one continuous
wall or form isolated studs. Preferably, they form
uniformly spaced parallel lines with a pitch p which
may vary from 0.2 to 30 mm, going from near one edge of
the substrate as far as the opposite edge.
According to another feature of the invention, the
cross section of the elements may adopt various forms.
Thus, the cross section is, for example, of triangular
shape, the base of the triangle being incorporated into
the substrate. It may also have a concave curved
geometry at the body of the; substrate and a
substantially straight neck at the top. As a variant,
the cross section is in the form of an arch, so that
the volume constitutes a semicylinder.
According to other features, the height of these
elements may vary from 0.15 to 12 mm, the top of these
elements may form a flat whose width is less than
500 µm, whereas their base may have a width of 50 µm to
One way of using the structured substrate of the
invention is, in particular, as a plasma screen which
comprises said structured substrate constituting the
rear face of the screen, and a flat substrate
constituting the front face of the screen, the flat
substrate being provided on its internal face facing
the internal face of the structured substrate with a
first electrode array, the plasma screen being
characterized in that a second electrode array
approximately perpendicular to the first array is
placed on the internal face of the structured substrate
in the space lying between the raised elements, while a
dielectric covers said second electrode array and
phosphors are housed in said space above the
According to a plasma screen variant, the second
electrode array on the rear face approximately
perpendicular to the first array on the front face is
placed on the external face of the structured substrate
and opposite the space lying between the raised
elements, while phosphors occupy, surfacewise, the
space lying between the raised elements.
In this plasma screen variant, the rear face electrodes
are advantageously placed on the external face of the
substrate, that is to say outside the screen and not
inside the screen. There are many advantages to this:
- there is no longer a need for a dielectric for
this electrode array as the thickness of the
substrate provides the dielectric function;
- once the screen has been assembled, it is
always possible to carry out a repair on the
- one of the sources of internal contamination of
the screens, due to evaporation and incomplete
combustion of the organic compounds
constituting the binders for screen-printing
the electrodes, is eliminated as is also the
risk of contaminating the phosphors with the
electrode materials of Ag type.
Finally, according to the latter screen variant, and in
particular when the raised elements have a flat at
their top, a third electrode array parallel to the
second array may be provided, placed on the external
face of the substrate and opposite the tops of the
raised elements, while phosphors occupy, surfacewise,
the space lying between the raised elements.
The structured substrate of the invention, in
particular in its use for a plasma screen, comprises a
multitude of walls, constituting the ribs, which are
mutually parallel and extend from one edge of the
substrate to the opposite edge, the two lateral walls
of the two respective edges of the substrate being of
larger width than the intermediate walls so as to
provide a bearing surface of sufficient contact in this
peripheral region for sealing the two substrates of the
The structured substrate of the invention may, of
course, be used in other embodiments, it being possible
for the raised elements to constitute simple spacers
between two walls, whether, for example, between two
faces of an FED screen for example, or between bottom
and cover of a plane lamp.
According to the invention, the process for
manufacturing the structured substrate is characterized
in that the substrate is obtained by extrusion, flat
glass being introduced under high pressure into a die
heated so that the glass reaches a temperature close to
the softening temperature.
Preferably, glass is extruded by means of a die in
order to form an intermediate substrate incorporating
raised elements, which substrate has a cross section
substantially identical in shape to that which it is
desired to obtain, to within a homothetic ratio, and
then the intermediate substrate is drawn in order to
constitute the final substrate of desired cross
More specifically, flat glass is introduced into the
die which is heated so that the glass reaches a
temperature close to the softening temperature, the
bottom of the die being machined so as to have the
cross section of the intermediate substrate to be
delivered by extrusion on leaving the die, and then the
intermediate substrate is drawn by drawing means with a
draw ratio (f) at the temperciture close to the
softening of the glass.
In a process variant, it is possible for the drawing to
take place in the die.
This extrusion-forming process allows very precise
dimensional control of a few thousandths of the objects
formed, which, combined with a homogeneous defect-free
glass composition, ensures precise control of the
electrical capacitance formed by the electrode and the
This results in greater uniformity, pixel to pixel, of
the voltages for igniting the ion discharge, since this
uniformity is in fact dependent on the exact height of
the rib, on the centering of the electrode with respect
to the phosphor and on the thickness of the dielectric.
Further features and advantages of the invention will
become apparent on reading the description which
follows, in conjunction with the appended drawings in
- figure 1 is a partial schematic sectional view
of a plasma screen of the prior art;
- figure 2 is a partial schematic sectional view
of a plasma screen according to the invention;
- figures 3 and 4 are alternative embodiments of
- figure 5 diagrammatically illustrates an
apparatus for implementing the process for
obtaining a structured substrate according to
- figure 6 is a sectional view from above of the
bottom of the die illustrated in the apparatus
of figure 5;
- figures 7a to 7d partially illustrate in cross
section several geometrical variants of the
raised elements incorporated into a substrate
of the invention;
- figure 8 is a partial schematic sectional view
of a plasma screen according to the invention
based on the geometry of the substrate
illustrated in figure 7b; and
- figure 9 is an additional geometrical variant
of the raised elements.
A known standard plasma screen as illustrated in
figure 1 is composed of a first glass substrate 10 and
a second substrate 11 which are parallel and placed
facing each other in order to constitute the rear face
and the front face of the screen, respectively. The
substrates are flat, that is to say they do not have
any particular element incorporated into their surface.
Placed on the respective internal faces 22, 23 of the
substrates 10, 11, which faces of the substrates face
each other, are layers constituting electrode arrays 12
and 13 respectively which are placed so as to be
mutually perpendicular, constituting what are called,
respectively, the rows and columns of the screen which
define the pixels.
The electrodes 12 on the rear face, for example made of
silver, are covered with a dielectric 14 based on low-
melting-point compounds, such as PbO, and the
electrodes 13a and 13b, for example a layer of ITO, are
covered with a dielectric 15, also based on PbO.
The electrodes 13a and 13b of the front face generally
form double electrode tracks, that is to say pairs of
two lines of electrodes spaced Apart by about 7 0 to
80 µm and connected together.
The electrodes 12 of the rear face of the screen are
also covered with a layer 16 of a phosphor. Each
phosphor, of red, green or blue color, is separated by
glass-based elements 20 of the "rib" type which extend
in the form of continuous walls over almost the entire
length of the substrate 10 along a multitude of lines
parallel to the longitudinal edges of the substrate and
are positioned uniformly with a pitch p of 0.3 mm for
example, which depends on the size of the screen and on
its resolution. The sides of the ribs are also
partially covered with phosphors, that is to say down
to the level of the thickness of the electrodes.
The volume 17 created between the two substrates 10 and
11 and in the channels 21 bounded by the ribs 20 is
filled with a gas, for example a mixture of neon and
xenon. During operation of the screen, the gas mixture
is excited by applying suitable voltages to the
electrodes 12, 13a and 13b, thereby generating Xe+ and
Ne+ ions emitting UV photons. The UV photons then
excite the phosphors, which convert the excitation
energy into red, green or blue visible light.
Three plasma screen variants using the structured
substrate of the invention are illustrated in figures 2
to 4 respectively; the elements common to the prior art
are identified by the same reference numbers.
Figure 2 reproduces the same arrangement of the
electrodes as that, in figure 1 on the front and rear
faces of the screen, the phosphors being isolated by
the ribs which, not being attached as in the prior art,
form an integral part of the substrate 11. The ribs lie
along several uniformly spaced parallel lines of pitch
p. The electrodes 12 of the rear face of the screen are
placed in the channels 21 boundesd by the ribs 20, a
dielectric layer 14 covering them and on the top of
these layers are the phosphors 16.
The variant in figure 3 benefits from the novel
configuration of the structured substrate of the
invention, providing a different arrangement of the
rear electrodes 12. These electrodes are placed so as
to face the channels 21 bounded by the ribs 20, and on
the outside of the glass substrate 10 on the external
face 24. No dielectric layer of the layer 14 type of
the prior art for these electrodes is then necessary as
the glass thickness of the substrate 10 very
advantageously fulfills the role of dielectric.
Although in the variants in figures 2 and 3 the glass
elements are incorporated on only one 22 of the faces
of the substrate, in another embodiment of the
substrate, in particular for a plasma screen, it may be
advantageous to form elements 20 on the two opposed
faces 22, 24 of the substrate, as illustrated in
The raised features 20 on the face 24 are at least
opposite the sides of the walls on the face 22 so that
grooves 25 are created on the opposite side from the
cups of the face 22 so as to house the electrodes 12,
made of Ag paste, on the rear face. This configuration
advantageously provides an impression which can
directly receive conductive paste deposited by a
squeegee, thereby making savings on the supply of
screen-printing screens and on the material of the
The process for obtaining a substrate according to the
invention, which intrinsically incorporates the rib-
type glass elements 20 will now be described. The
process for manufacturing a plasma screen will be
explained later so as to demonstrate the possibilities
of its implementation, which is provided by a substrate
structured in this way.
The process for obtaining the substrate according to
one embodiment is explained with regard to the
apparatus 30 diagrammatically illustrated in figure 5,
which is a sectional view in a plane perpendicular to
the plane of the glass ribbon. The apparatus 30
comprises a furnace 31, a piston 32 for driving the
glass, a die 33 capable of extruding an intermediate
glass ribbon 41, a thermal regulation system 34, which
gives the intermediate ribbon the temperature suitable
for drawing it, a system 35 for drawing the ribbon, in
order to deliver a final ribbon to the desired
dimensions, and cooling means (not visible in the
A flat glass strip 40, such as bubble-free float glass
containing no solid defects, is introduced under
pressure by means of the piston 32 into the furnace 31
and the die 33. The thickness of the glass may vary
from 5 to 20 mm depending on the availability of the
base material used and on the final application of the
structured substrate. The die is heated so that the
temperature of the glass can reach the softening
temperature. The bottom 36 of the die is made of
graphite for reasons of resistance to abrasion by the
The die bottom 36, illustrated in figure 6, is provided
with a cut 36a, the pattern of which is similar to the
cross section of the final substrate to be obtained, to
within a homothetic ratio. Advantageously, it can be
demounted from the body of the die so as to be able to
change it easily in order to adapt the type of pattern
to the desired profile of the substrate.
Several variants of patterns obtained for the glass
elements 20 are proposed in figures 7a to 7d as
Figure 7a illustrates one form of prismatic ribs having
a triangular cross section, the base of the triangle
being incorporated into the substrate. The vertex of
the triangle is preferably truncated in order to avoid
the spike effect during operation of the electrodes.
The cross section of the ribs in figure 7b has, on the
one hand, a concave curved geometry at the body of the
substrate, such that it is composed of two curves of
the exponential type which are symmetrical with respect
to an axis perpendicular to the plane of the substrate
and, on the other hand, a substantially straight neck
at the top. The radius of curvature of the concave part
may vary from 5 to 100 µm.
The ribs in figure 7c have a cross section in the form
of an arch, such that the volume of the ribs
constitutes a semicylinder.
It may be envisioned to combine ribs 20 of different
cross sections on the same substrate.
In the variant in figure 7d, there are raised elements
on both faces of the substrate, these being symmetrical
with respect to the plane of the body of said
substrate. Such a configuration allows symmetrical
cooling during the process of forming said substrate
and will increase the ability of the screen to
dissipate heat during operation, thanks to the effect
of fins provided by the raised elements.
On leaving the die, the extruded intermediate substrate
ribbon 41 has the cross section of the final substrate
ribbon 42 to within a homothetic ratio. It is then
drawn by the drawing means 3 5 by passing, immediately
downstream of the die, through the thermal regulation
system 34 which has the purpose of controlling and
adapting the temperature over the entire width of the
ribbon, which has, because of its dissymmetrical
profile, points of variable temperature. The
temperature of the ribbon, which has to be the
softening temperature, must be perfectly homogeneous
over the entire width of said ribbon in order to
guarantee a constant draw ratio f over the entire width
of the strip.
The draw ratio f may vary from 1 to 20 depending on the
Finally, the cooling system through which the final
substrate strip 42 passes allows the definitive shape
of the substrate to be set.
Conventional flat-glass cutting means (not
illustrated), or any other suitable means such as a
laser, are provided for cutting the strip 42 along its
width so as to supply structured substrates 10 to the
The substrates thus delivered will constitute the rear
faces of plasma screens, the body of the substrate
having, for example, a thickness of 1 mm and the glass
elements being 150 µm in height.
The plasma screen of the invention as illustrated in
figure 3 is manufactured in the following manner.
The structured substrate 10 is held by suction, using
suitable means, in a horizontal position, its external
face 24 devoid of ribs being turned uppermost. A
uniform silver layer in the form of a paste is
deposited by screen printing on this external face.
The silver paste is advantageously photosensitive so as
to fix it by exposing the substrate to a UV beam.
Consequently, when the layer has undergone the drying
step, the substrate is turned upside down, with the
internal face 22 provided with ribs turned uppermost,
in order to receive the UV beam intended to sensitize
the UV activators of the photosensitive silver paste.
The raised geometry of the substrate, defined
homogeneously by the ribs 2 0 which form in succession
the walls for isolating the colors and the channels 21
forming flat-bottomed cups intended to receive the
phosphors, makes it possible to focus the UV rays all
the better onto the bottom of the cup, so that the Ag
electrodes 12 are, after development, positioned
precisely along lines opposite the; cups. No photomask
is then needed as in the prior art, which represents an
additional pecuniary saving in the manufacturing
process. Furthermore, the wall/cup structure
incorporated into the substrate and the method of
depositing the paste ensure that, whatever the
linearity of the ribs, the Ag electrodes are self-
aligning, this being an essential characteristic for
guaranteeing a high level of uniformity of the ignition
voltages during operation of the screen.
The development of the electrodes 12 is carried out in
a known manner by a wet route and is followed by a
baking operation at high temperature of the order of
The substrate with symmetrical raised features, as
illustrated in figure 7d, makes it possible very
advantageously to produce silver electrodes self-
aligned with the ribs inside the screen, using a
photosensitive silver paste, without the need for a
photomask. To do this, all that is required is to
deposit the photosensitive silver layer on the inside
of the screen and to expose it to the ultraviolet rays
via the opposed structured face, on the outside.
To obtain a region for sealing the two glass
substrates, as will be explained below, the ribs of the
lateral ends of the substrate are not used for
depositing the electrodes and phosphors; their cross
section may moreover be different from that of the
Immediately alongside these lateral end ribs may be
reserved ribs for housing elements involved in the
operation of the product, such as getters well known to
those skilled in the art, these elements placed around
the periphery of the image not having to be in contact
with the phosphors, the plasma or the sealing frits.
In the geometrical variant of the ribs with reference
to figure 7b, the flatness of the tops of the ribs
results in the formation, on the external face 24 of
the substrate and opposite said tops, of a second
electrode array 12a parallel to the electrode array 12
placed opposite the cups (figure 8) . The external face
24 is in this case plane, but it could just as well be
structured as in figure 4; grooves would then be placed
not only opposite the cups but also opposite the tops.
This second electrode array allows, via a connection to
the electrodes 12, rapid repair of the latter if they
possibly become damaged.
The step following the deposition of the electrodes on
the rear face of the screen consists in depositing the
phosphors by electrophoresis, by biasing the
electrodes. This technique is well known in the
manufacture of television sets, the phosphors being
deposited on the front face of the cathode-ray tubes.
By biasing the electrodes on the face 24 of the
substrate, the phosphors may thus be deposited on the
bottom of the cups of the channels 21.
The voltage values applied to the electrodes are
adjusted according to the partictilar geometry of the
The geometry of the ribs in figure 7b, which makes it
possible to obtain two arrays of mutually adjacent
electrodes, facilitates the deposition of the phosphors
not only in the bottom of the cups but also on the
sides of the walls.
After the phosphors have been dried, a sealing frit is
put into place for the purpose of fastening together
the two glass substrates of the screen. The structured
substrate 10 is laid on a metal support fitted with
suction and uniform-heating means. A sealing frit is
applied around the periphery of the structured
substrate 10, that is to say in the cups of the two
lateral end ribs and along the two adjacent sides in
the ends of the cups of the intermediate ribs.
Finally, the front face substrate 11, which has the
electrodes 13 screen printed beforehand, is positioned
over the structured substrate 10 resting on the top of
the ribs, the electrodes 13 of the substrate 11 lying
perpendicular to the electrodes 12 of the substrate 10.
The entire screen is housed in a closed chamber in
which a vacuum is created in order to evacuate between
the substrates. Gas is then introduced into the screen
via the gap lying between the two non-compressed
substrates. The two substrates are then fastened
together via the sealing frit by compressing and
heating the assembly in the chamber, operating under a
controlled atmosphere in order to guarantee a high
level of temperature uniformity.
In order to benefit from the structure of the substrate
with incorporated ribs, a variant in the substrate-
fastening and gas-filling steps may be envisioned.
Thus, with regard to the sealing frit, this may be
placed only on the two sides of the structured
substrate 10 which will be placed vertically in the
mounted position of the screen, that is to say along
the sides parallel to the ribs, thereby allowing the'
channels 21 formed by the ribs to project freely. After
placing the front face substrate 11 on the structured
rear face substrate 10, the channels 21 of the ribs are
connected by means of a sucker system to a vacuum,
purging and filling device. The device carries out, in
succession, the steps consisting in creating a vacuum
in the channels, purging with an inert gas, such as
argon and filling with the discharge gas. The free
circulation of the fluids from one channel to another
and the means of direct connection with said device
shortens the time for carrying out these steps.
The resulting effectiveness is not insignificant since
the operation goes from 24 hours in the case of the
conventional gas introduction solution to a few hours
in the case of this method of implementation, providing
a substantial saving on the cost of assembling the
Once filling with gas has been completed, the channels
are closed by local heating and mechanical stamping of
the edges of the two substrates that do not have a
sealing frit. The other edges, associated with the
sealing frit, are fastened together by compressing and
heating said edges.
Similar operating steps with regard to the use of the
structured substrate of the invention may be applied to
other operations, such as the manufacture of plane
In a known manner, a plane lamp comprises two facing
substrates which are held apart by means of spacers in
order to form a space containing a discharge gas.
For a plane lamp according to the invention, one of the
two substrates is flat while the; other is structured,
the raised glass elements 20 constituting the spacers.
In a variant of the spacers, the glass elements are in
the form of isolated studs obtained by sawing and
grinding the continuous extruded ribs.
Of course, the structured substrate of the invention
can be used in any application which either requires a
space to be maintained between two glass walls, the
glass elements 20 acting as spacers, or which gives the
substrate a novel technical property.
For example, intended for the spacer function are FED
screens and applications in the building industry where
it is necessary to maintain a constant distance between
two substrates. Mention may be made, for example, of
vacuum double glazing or of double glazing in which it
is desired to make a functional liquid circulate.
Consequently, the dimensions of the bases, tops and
heights of the raised elements 20 and the pitch between
the elements, together with the thickness of the body
of the substrate, vary depending on the envisioned
application of the structured substrate. The table
below summarizes a few values for the applications,
namely plasma screen, plane lamp, FED screen and
With regard to the technical novelty that a substrate
of the invention may provide, it may be envisioned to
produce microlenticular panels which are attached to
flat display screens so as to obtain a three-
dimensional perception of the image. A microlenticular
panel thus consists of a substrate according to the
invention, which is flat on one of its faces intended
to be placed on the screen, and structured on its
opposite face with semicylindrical raised elements
forming the lenses, as illustrated in figure 9. The
thickness of the body of the substrate may be between 2
and 5 mm, the base of a raised element 20 or the pitch
of the lenses may vary from 0.15 to 2 mm, and the
radius of curvature of the semicylinders may be between
1 and 3 mm.
1. A glass substrate comprising raised glass elements (20)
placed over a part of its area, characterized in that the glass
elements (20) are intrinsically incorporated into the substrate.
2. The substrate as claimed in claim 1 wherein the body of
the substrate has two opposed parallel faces the elements (20)
being incorporated into at least one of the two faces.
3. The glass substrate as claimed in claim 1 or 2, wherein
the elements (20) lie along at least one line approximately
parallel to one side of the substrate.
4. The substrate as claimed in claim 3 wherein the elements
(20) form at least one continuous wall.
5. The substrate as claimed in claim 3 wherein the elements
(20) form isolated studs.
6. The substrate as claimed in amy one of the preceding
claims, wherein the elements (20) lie along several uniformly
spaced parallel lines going from near one edge of the substrate
as far as the opposite edge.
7. The substrate as claimed in claim 6 wherein the parallel
lines are spaced apart with a pitch (p) varying from 0.2 to 50
8. The substrate as claimed in any one of the preceding
claims wherein the elements (20) have a cross section of
triangular shape the base of the traingle being incorporated
into athe substrate.
9. The substrate as claimed in any one one of claims 1 to
7 wherein the elements (20) have a concave curved geometry at the
body of the substrate and a substantially straight neck at the
10. The substrate as claimed in any one of claims 1 to 7
wherein the elements (20) have a cross section in the form of an
11. The substrate as claimed in any one of the preceding
claims wherein the elements (20) have a height of between 0.15
and 12 mm.
12. The substrate as claimed in any one of the preceding
claims wherein the top of the elements (20) forms a flat whose
width is less than 500 µm.
13. The substrate as claimed in any of the preceding
claims wherein the elements (20) have a base with a
width varying from 50µm to 50 mm.
14. The substrate as claimed in claim 3 wherein it
includes a multitude of mutually parallel walls
extending from one edge of the substrate to the
opposite edge, the two lateral walls of the two
respective edges of the substrate being wider than
the intermediate walls.
15. The substrate as claimed in any one of the preceding
claims in the production of a display-type screen,
such as a plasma screen.
16. The substrate as claimed in any one of claims 1 to
14 for the production of a plane lamp.
17. A process for manufacturing a substrate as claimed in
any one of claims 1 to 14, wherein the substrate is
obtained by extrusion, flat glass being introduced
under high pressure into a die (33) heated so
that the glass reaches a temperature close to the
18. The process for manufacturing a substrate as
claimed in claim 17 wherein glass is extruded by
means of the die (33) in order to form an
intermediate substrate (41) incorporating raised
elements, which substrate has a cross section
substantially identical in shape to that which is
desired to obtain, to within a homothetic ratio,
and then the intermediate substrate is drawn in
order to constitute the final, substrate (42) of
desired cross section.
19. The process as claimed in claim 18 wherein flat
glass is introduced into the die (33) heated to
that the glass reaches a temperature close to the
softening temperature, the bottom of the die being
machined so as to have the cross section of the
intermediate substrate to be delivered by
extrusion on leaving the die, and then the
intermediate substrate is drawn by drawing means
(35) with a draw ratio (f) at the temperature
close to the softening of the glass.
20. The process as claimed in claim 18 wherein the
drawing takes place in the die.
A glass substrate comprising raised glass elements (20)
placed over part of its area, characterized in that the glass
elements (20) are intrinsically incorporated into the substrate.
|Indian Patent Application Number
|PG Journal Number
|Date of Filing
|Name of Patentee
|SAINT-GOBAIN GLASS FRANCE
|18, AVENUE D'ALSACE, F-92400 COURBEVOIE
|PCT International Classification Number
|C03B 23/037, 17/06
|PCT International Application Number
|PCT International Filing date