Note: Descriptions are shown in the official language in which they were submitted.
CA 02383813 2002-03-O1
s ELECTROMAGNETIC IRRADIATING DEVICE
Technical field of the invention
1o
The invention concerns an electromagnetic irradiating device comprising
~ an electromagnetic radiation source comprising
~ a radiation emitter,
~ at least two lateral reflectors situated at a certain distance
1s from of the emitter on either side thereof, and comprising
each a reflecting front surface opposite the emitter, and a
rear surface, the emitter and the reflectors being laid out in
order to direct the radiation towards a exposed space having
a median part, both reflectors being isolated from one
2o another by a slot,
~ means for cooling the reflectors allowing a cooling fluid to flow from
one side of the rear surface of the reflectors on the one hand, and
through the slot on the side of the front surface of the reflectors on
the other hand,
2s ~ and a carrying structure fitted with a recess for the radiation source.
Devices with visible and/or ultraviolet and/or infrared radiations for
applications such as the drying of paints, varnishes, inks, the baking of
powders such as epoxy, Rilsan (registered trademark), etc., and such as the
3o sterilization of solid coat products, foodstuff fluids, syrup, water
etc.... and,
more especially for the polymerization of inks andlor varnishes, radicalar
and/or cationic and/or adhesive items and/or any other change in state
generated mainly by radiations, in the field of Graphic Designing and for
continuons treatment of coatings or leaf wise treatment of supports such as
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2
s payer, cardboard, cotton or other synthetic products, plastic, PVC, PVB or
metal bands made of aluminum or steel or other metals, or any other
products used in print, security payer, stationery, cardboard mill, plastics
technology, bags production, wrapping, textile, automotive industry, wood
manufacture, electronics, credit cards, CD, etc., are known
1o
Prior art
The documents US 5861633, JP 07256190, W098/01700 and W099136939
describe an electromagnetic radiation source comprising irradiating means
Is consisting of a radiation emitter and of two lateral reflectors situated at
a
certain distance from the emitter on either side thereof. Each reflector
comprises a reflecting front surface opposite the emitter and a rear surface.
The emitter and the reflectors are laid out in order to direct the radiation
towards an exposed space. Both reflectors are isolated from one another by a
2o slot and means for cooling the reflectors enable a cooling fluid to flow
from
one side of the rear surface of the reflectors on the one hand, and through
the
slot on the side of the front surface of the reflectors on the other hand. The
reflectors consist of concave metal sheets whereof a face is reflecting. They
form two portions of the saure ellipse, whereas the slot occupies the apex of
2s the ellipse. The emitting tube is situated parallel to the slot, and its
axis is
placed at the focus of the ellipse closest to the slot.
The thermal energy released by the radiation source simultaneously with the
photochemical energy tends to dry the product subject to the radiation. If one
3o considers the example of an application to the printing industry, the
source
may perfectly irradiate zones of the payer whereon the product to be
polymerized has not been printed, in which case the substrate (for example
payer) being tiare, the air and the heat are responsible for localized drop in
the humidity ratio, which will alter the structural behavior of the
substrates.
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s This stress limits in certain applications the power of the device.
Besides, the thermal stresses exerted on the device properly speaking are
enormous. The thermal deformations of the different elements, such the risk
of devitrifying the envelope of the emitter, must be taken into account during
1o the sizing stage. 1t is rather difficult to design a housing liable to
accommodate elements of the device in a confined space while enabling
satisfactory ventilation.
1s
Object of the invention
An object of the invention is to enable sufficient cooling of an irradiating
device
of the previous type, in a confined space in a housing. Another object is to
2o provide for ventilation and, if possible, sufficient cooling of the space
subject
to radiation without detriment to the photonic energy released. Another object
is for increasing the power of the radiation source, in a given volume,
without
exposing the radiation source itself and/or the item subject to the radiation
to
any excessive heating, by simple means.
2s
According to the invention, these objects are met thanks to an irradiating
device comprising:
- a cavity provided in said recess to carry the cooling fluid emerging on the
side of the exposed space through one or several discharge outlets
3o capable of directing the fluid towards the median part of the exposed
space,
- a fin shaped like a projecting rib extending on the side of the rear surface
of each reflector while forming simultaneously a cooling surface, and a
means for increasing the inertial moment of the profile of said reflector,
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s - and a hook-shaped rim at each end of said fin letting through means for
fixing reflectors to positioning flanges.
The median part of the exposed space is that which is subject to highest
temperatures. Thanks to the invention, it is swept by the cooling fluid
1o emerging simultaneously through the discharge outlets and through the slot,
which contributes to its cooling effect. The circulation of the cooling fluid
between the rear surface of the reflectors and the carrying structure enables
increased thermal exchange, and limits significantly the overheating of the
carrying structure.
1s
The cooling fluid may be the amblent air of the room or an inert gas, such as
nitrogen, for the products to be inertized. Alternately, it may also be air
with
high relative humidity ratio, promoting the temperature drop by making use of
the latent vaporization heat, or cold air whereof the temperature is lower
than
20 20°C or lower than 0°C, or even demineralized liquid water at
room
temperature.
Advantageously, the reflectors are fitted, on the side of their rear surface,
with
a great number of cooling ribs, so that the exchange surface formed by the
2s rear surface of the reflectors is significantly larger than the reflecting
surface
formed by the front surface of the reflectors. The recess comprises suitably
shaped walls, so that the cavity that they form with the rear surface of each
reflector is a winding cavity for increasing considerably the thermâl exchange
capacity. the reflector will be subject to a surface treatment by a nickel
deposit
3o multiplying approx. tenfold the thermal emissivity capacity on the back of
the
reflector with respect to tiare aluminum. The small ribs and the
complementary conformation of the carrying structure enable to increase the
exchange surfaces simultaneously on the side of the reflector and on the side
of the carrying structure, hence its higher cooling power.
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S
According to an embodiment, the thickness of the winding cavity is
substantially constant.
Advantageously, the carrying structure comprises a distributing conduit for
the
lo cooling fluid laid out parallel to the slot. The device comprises at least
one
channel linking each winding cavity to the conduit. The conduit is isolated
from
the cavity by an intermediate watt comprising one or several communication
orifice forming the fluid channel linking the winding cavity to the conduit.
The
cross-section of the discharge outlet(s) is substantially smaller than the
is cross-section of the communication orifice(s).
Advantageously, the intermediate watt comprises at least one orifice linking
the conduit to the slot. That orifice may besides be one of the previous
communication orifices.
According to an embodiment, the rear surface of the reflector comprises at
least one stop carrying on a complementary stop formed in the structure, the
resultant of the forces caused by the pressure exerted by the fluid on the
rear
surface of the refiector tending to increase the force exerted by the stop on
the
2s opposite stop. The device thus allows for good distribution of the
mechanical
and thermal stresses between the reflectors and the carrying structure.
Preferably, the device comprises the power-driven means normally externat to
the irradiating device, involving forced circulation of the fluid in the
conduit.
3o These power-driven means may be integrated to the carrying structure or
isolated from said structure by a supply conduit of the fluid.
Advantageously, the device comprises a nebulizer projecting into the fluid a
liquid as fin droplets. The nebulizer is preferably placed between the power-
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s driven means and the distributing conduit of the fluid. The nebulized liquid
is
sprayed, on the one hand in contact with the emitting tube when flowing round
it and towards the front surface, and on the other hand when going through
the cavity formed between the reflectors and the carrying structure, thus
absorbing considerable heat corresponding to its own latent vaporization
lo heat, and contributing to the cooling of the emitter and of the watts.
Advantageously, the vaporized liquid is demineralized water, which enables to
control the humidity ratio in the exposed space and to prevent the objects
subject to radiation from drying up or to accelerate the polymerization of
certain inks or varnishes.
Is
The electromagnetic radiation source forms a stand-atone monobloc
assembly mounted to slip and resting on two orthogonal axes in the aeraulic
carrying structure by means of spans sliding over the rests, and of rails
sliding on bosses.
Brief description of the drawings
Other advantages and characteristics of the invention will appear clearly from
the following description of various embodiments of the invention, given for
2s non limiting exemplification purposes and represented on the appended
drawings whereon
~ Figure 1 represents a transversal cross-section of a device according' to
the invention ;
~ Figure 2 represents an exploded and detailed perspective of the device of
Figure 1;
~ Figure 3 represents a side view of the device of Figure 1 ;
~ Figure 4 represents a cross-section of the portion of the device
represented on Figure 2 ;
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7
s ~ Figure 5 represents a detail of an embodiment variation of the invention.
Description of preferred embodiments
With reference to Figures 1 to 4, an irradiating device 10 comprises a
carrying
lo structure 12 formed by an A-shaped profile of aluminum or of steel
protected
by an insulating coating, and an intermediate watt 14 delineating a rear
volume forming a longitudinal conduit 16 of rectangular section and a front
volume forming a recess 18 shaped approximately as a reverted U, open on
one of its sides. One of the ends of the conduit 16 is fitted with an aeraulic
ls mouth 20 for supplying the cooling fluid.
The aluminum profile has been subject to a hard anodic oxidization treatment
of approx. 50 p, whereas the surface protection coat thus formed enables to
sustain on the one hand all the mechanical shocks, and conferring on the
20 other hand to the part high electric resistance to leakage currents in the
surrounding of the machine whereon the irradiating device is mounted, s to
the possible short-circuit currents inside this very irradiating device. The
ground convection of the irradiating device is isolated from the ground
convection of the machine.
2s
The intermediate watt 14 comprises the orifices 22 of variable sections laid
out staggered on either side of a median plane 24 of the carrying structure,
whereas these orifices 22 providing as many openings between the conduit
16 and the front recess 18 of the structure 12. The intermediate watt 14 is
3o fitted with two rests 26 placed on either side of the median plane 24 and
protruding towards the inside of the front volume 18.
Both lateral watts delineating the front volume 18 of the structure comprise
on
their externat surface each a longitudinal groove 28 of circular section,
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ô
s corresponding to a boss 30 formed inside the front volume 18.
The front volume 18 of the structure 12 is occupied by of the irradiating
means
comprising an emitter 32 situated in the median plane of the structure, and
two lateral reflectors 34 situated on either side of the emitter 32 and at a
1o certain distance thereof, symmetrically with respect to the median plane.
The emitter 32 is a lamp filled with Xenon or Krypton or Neon or any other gas
having comparable properties, composed of a cylindrical tube 36 made of
transparent quartz, inside which is laid out a plasmatic cylinder emitting in
the
is ultraviolet andlor in the visible and/or in the infrared range.
The interest of such an emitter lies in its pulse generation. The variation of
the
electric supply parameters of the generator enables to mix simultaneously
and in required proportions, wavelengths UV with those of the infrared IR, and
2o that at each flash on the saure irradiated surface. With the succession of
the
flashes, it is also possible to provide a first flash UV, followed by a second
flash IR, or vice versa, or still, a first flash UV combined with in a smaller
proportion with a certain quantity IR, followed by another flash IR combined
with in a smaller proportion a certain quantity UV on the saure irradiated
2s surface. Each of the axial ends of the tube is fitted with a ceramic
connection
piece 38 fitted with an externat electric connector 40 linked to an electrode
42
inserted in the tube.
The emitter 32 may also advantageously consist of a lamp filled with Mercury
30 or metal iodide derivatives thereof.
At each longitudinal end of the front volume 18 of the carrying structure 12
is
laid out a positioning flange 44, visible on Figures 2 and 4, and comprising
lateral rails 46 which, in order to assume their positions, slide on both
lateral
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s bosses 30. Each flange exhibits a U-shaped scalloping 48 whereof the
opening is turned towards the intermediate watt, and an internat reflecting
surface 48a of the flange 44 bringing the radiation of the source 36 towards
the irradiated plane in order to eliminate the rim effects. That scalloping
comprises a shoulder 47 visible on Figure 4, and a wider portion for
lo positioning a punched retaining piece 49. This retaining piece 49 may also
be
advantageously replaced with a part made of Teflon or similar material
whereof the thickness and the diameter are sufficient for the recess of the
'O'
ring of the ceramic connection piece 38 having as externat geometrical
contour the saure design as the part 44 thus providing the symmetry with
Is respect to the axis 54.
As a variation, the retaining piece 44 may bee advantageously replaced in the
externat plug 72 by a blind hole positioned in the axis of symmetry of the
lamp.
The externat 72 and internat 74 plugs form the saure part molded of insulating
2o material. The ceramic connection piece of the lamp may then be maintained
in the blind hole of the plug 74, either by an 'O' ring, or by an elastomer
binder
insensitive to the UV and temperature resistant.
The intermediate watt 14 comprises, at the saure height as the convection
2s between the tait of the electrode and the ceramic convection piece, a large
opening 50. The flange is itself punched by the openings 41.
Each of the reflectors 34 consists of a metal profile, notably of aluminurn or
steel, comprising a reflecting concave front surface 52. Seen as cross-
3o sections in a plane perpendicular to the axis 54 of the cylindrical tube
36, the
reflecting surfaces 52 of the two reflectors 34 match the envelope of the
saure
ellipse whereof the focus would be situated on the axis 54 of the cylindrical
tube. Each of the reflectors 34 is fitted, on the side of its rear surface 56,
with a
large main fin 58 and with cooling ribs 60 forming smaller roughnesses. A
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s span 62 contributes to the positioning of the reflector in the carrying
structure
12 and stop against the corresponding rest 26 of the intermediate wall 14.
Two adjacent edges 64 of both reflectors 34 delineate a longitudinal slot 66
parallel to the axis 54 of the tube 36. a space is formed between the slot 66
1o and the intermediate wall 14, emerging laterally on the orifices 22. In the
vicinity of the aeraulic mouth 20, the speed of air in the conduit 16 is
higher
than at the other opposite end at the electric convection tapping 78, where
speed tends to be equal to zero. Thus, to obtain uniform air distribution
along
the aeraulic mouth 20, the air pressure increasing as the speed decreases,
Is the through section of the orifices 22 is larger where the pressure is
reduced.
The through section of these orifices 22 reduces gradually up to the other
opposite end 78 where the pressure is higher, in order to make the
transversal air flow homogeneous after the intermediate wall 14.
2o Both flanges 44 receive the ends of the fateral reflectors 34 in order to
position
said reflectors longitudinally in the front recess 18.
The cooling air is carried at the back of the reflectors 34 with a pressure
greater than the foad loss caused by the circulation of air through the air
path
2s 17. The presence of the rib 58 and of the hook-shaped end rim 59 increases
the inertial moment of the reflector 34 with respect to the thrust axis of the
air
pressure at the back of the reflector, in order to eliminate any deformation
of
the reflector 34 made of extruded profile. Moreover, the reflector 34 for long
radiation devices (up to 4 meters), significantly in the industries producing
3o cardboard or textile machine widths, is maintained rigorously rectilinear
by the
rib 58, whereas the reflector rests 34 on the stop 26 of the intermediate wall
14. Both reflectors 34 remain perfectly symmetric and immobile with respect
to the axis 24, as the opposite thrusts negate each other.
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s The rear of each reflector 34 is shaped according to a very efficient heat
exchanger. To do so, the reflector assembly 34 is covered with a coat of
nickel
enabling to multiply by 10 the calorific emissivity coefficient with respect
to a
tiare aluminum surface. Moreover, wherever the cooling air sweeps over the
back of the reflector 34, the irradiating surface has been increased by the
small ribs 60 staggered at three points: the top of the reflector, on the rib
58
and on the slope at 15° in the median and low part of the reflector 34.
The intermediate watt 14 retains in its median part by the recess 15 an
aluminum reflecting longitudinal blade 68, maintained by two rests 15' and
Is facing the tube 36 through the slot 66.
Each end of the carrying structure 12 is equipped moreover with an externat
plug 72 and an internat plug 74, visible on Figures 2 and 4. The externat plug
72 closes the conduit 16. 1t is fitted with four studs 76 inserted in circular
2o grooves of the carrying structure. The internat plug 74 is round and
therefore
changes the direction of flow of the cooling fluid by 90° and, by its
construction, guarantees sufficient electric insulation to seal the electric
connection point of the lamp with its supply Gable. The plugs 72, 74 are made
of plastic material, in order to match the shapes of the profile by engaging
into
2s said profile, while reinforcing electric insulation.
The end of the structure opposite the aeraulic mouth is fitted with a multipin
electric tapping 78, represented on Figure 5, for lame supply voltages smâller
than or of the order of 3,000 Volts. Beyond these values, i.e. up to 10,000
Volts
30 or above, the electric conductors go through the ventilation sheath which
ensures additional insulation as regards human safety.
The aeraulic mouth 20 is connected by a piping 99 downstream of a fan 96,
represented schematically on Figure 3. Optionally, the device is fitted
besides
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12
s with a spray 98 situated at the discharge of the fan, which enables
discharging towards the aeraulic mouth 20 and the air conduit 16 containing a
mist of thin water droplets in suspension. According to a variation, the spray
98 may be laid out directly in the vicinity of the aeraulic mouth 20.
lo The device is assembled as follows:
The longitudinal ends of the reflectors 34 are integral with the flanges 44 by
means of eight pins 53 housed in the holes 55 arranged in the end returns
59, and going through the holes 45 of the two flanges 44. The electric
ls connection of the emitter 32 at one of the ends of the irradiating device,
the
electric supply wire of the other side of the larnp is brought back to the
side of
the elèctric connection through the hole 57 of the reflector 34. The hole 57
of
the other reflector 34 is used to accommodate a bare ground conducting wire.
2o Thus, both end flanges 44, both reflectors 34 and the emitter 32 form a
stand-
alone sub-assembly, mechanically and electrically integral, which may be
inserted by sliding along the bosses 30 in the front volume 18 of the
structure
12, whereas the spans 62 slide on the rests 26. This sub-assembly i s
therefore vastly dissociated, from a mechanical, electrical, thermal and
2s aeraulic viewpoint, of the carrying structure 12. A continuous space is
formed
between each lateral reflector 34 and the lateral watt opposite the carrying
structure 12, this space emerging on the front side by a slot 80 situated
between the front edge of each reflector and the corresponding edge of the
watt of the carrying structure 12, et, on the rear side, through the orifices
22
3o drilled in the lateral watt. Once this sub-assembly has been inserted and
positioned in the carrying structure 12, the pins 53 which maintain the
reflectors 34 integral with the flange 44 emerge on the rear surface thereof
over such a length that they stop against the internat surface 73 of the
internat
plug 74 whereof the plastic material is sufficiently elastic to absorb the
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s dilatation of the reflectors 34.
The externat grooves 28 of the carrying structure enable to insert the device
10
as a drawer in an element of machinery fitted with complementary parallel
rails. The compactness, the handiness and the unity of the assembly enable
to contemplate as parts exchange the complete replacement of the device
during maintenance operations or calls, rather than a repair or partial
replacement of one of the components of the device.
In operation, the thermal and aeraulic behavior of the device is as follows:
Is
A cooling fluid is injected in the conduit through the mouth 20. The cross-
section of the orifices 22 differs from the end comprising the mouth 20
towards the opposite end, in order to compensate for the pressure variation
along the conduit 16 and to cause the fluid to flow at substantially constant
2o rate through the orifices 22. A portion of the fluid flows through the slot
66
towards the space exposed to the radiation, where it partakes of a thermal
exchange with the reflecting surfaces 52 of the reflectors and with the tube
36.
Another portion of the flow follows the winding path formed between the
fateral
watts of the structure 12 and the rear surfaces 56 of the reflectors 34 and
2s emerging through the slots 80, which direct the outgoing flow approximately
towards the median plane 24 of the irradiated space. This portion of the fluid
performs a thermal exchange with the rear surface 56 of the reflectors, which
is important because of the lerigth of the distance 17 covered which
contributes simultaneously to increase the exchange surface and to slow the
3o fluid down. The small ribs 60 and the nickel coating also contribute to
increase this thermal exchange.
A the ends of the emitter 32, the openings 50 and 41 enable the fluid to flow
and hence the cooling to take place.
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14
s
The reflecting blade 68 enables reflection of the radiation from the slot 66.
1t
also insulates the intermediate wall 14 from any contact with the infrared
radiations which might cause localized overheating of the profile making up
the carrying structure 12 and generate heterogeneous deformations of the
1o elements.
The different thermal dilatations of the reflectors 34 and of the structure 12
cause the flanges 44 to slide with respect to the bosses 30, as well as the
spans 62 with respect to the rests 26, whereas the displacement of the ends
1s of the irradiating assembly is absorbed by the elasticity of the internat
plugs.
The rests 26 oppose the mechanical thrust generated by the pressurized fluid
along the rear surfaces of the reflectors 34, and thus guarantee the existence
of a slot 66 of constant width and homogeneous between the adjacent edges
20 64 of both reflectors 34, regardless of the aeraulic thrust.
The word 'cooling' used so far is purposely general. Indeed, if the radiation
emitter comprises plasmas sensitive to thermal shocks, such as for example
when lighting a lamp, or high temperature gradient of the quartz envelope,
2s which affects essentially plasmas formed by Mercury, Gallium andlor Lead,
Iron and/or Cobalt and/or other metal iodides of similar nature, then the
cooling of the emitter will be restrained to the usage of amblent air in the
room
or of neutral gases, such as nitrogen, for products to be inertized.
3o Conversely, if the radiation emitter comprises plasmas quasi insensitive to
thermal shocks, such as those formed by Xenon, Krypton or by other
associated ionizing gases of the saure nature, whereas, on top of the amblent
air, one may use as a replacement either a neutral gas, inherently anti-
oxidizing inasmuch as the emitter is with cold plasma, or inasmuch as the hot
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ls
s plasma emitter is fitted with a jacket of demineralized cooling water as it
has
been described previously, i.e. air at relative humidity ratio thanks to the
water
spray, preferably demineralized water, promoting the temperature drop by
using the latent vaporization heat, or air at a temperature lower than
20°C or
lower than 0°C, even demineralized water at room temperature, wherein
the i s
io immersed the irradiating element. Demineralized water offers electric
resistivity enabling the conducting ends of the lamp to corne in contact with
the cooling water without any risks of electric faults.
ts Spraying water through the slot 66 provides high temperature gradient
between the internat watt of the quartz tube 36 which is in contact with the
plasma at approx. 5,000°K to 7,000°K, and the externat watt
which may be in
direct contact with water at 20°C without modifying the plasma nor its
spectrum, nor the quantity of energy released in the wavelengths considered.
2o One shall therefore use the latent heat of the water in suspension in the
cooling air at pre-set temperature, significantly amblent, in contact with the
quartz tube of the emitter.
Besides, it should be noted that the thermal energy released simultaneously
2s to the photochemical energy tends to dry up the product subject to
radiation. If
one takes the example of an application to the printing industry, the
irradiating
device 10 may quite well irradiate the zones of the paper whereon the product
to be polymerized has not been printed, in which case the substrate (for
example paper) being bave, the air and the heat cause localized drop of the
3o humidity ratio, which will affect the structural behavior of the substrate.
1t is then possible to avoid any drying effect by increasing the humidity
ratio of
the cooling air that is propelled onto the irradiated surface of the product.
One
should then direct the discharged air towards the median part of the zone
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16
s subject to radiation. The air going through the slot 66 heads naturally in
that
region. The discharge slots 80 formed between the lateral reflectors and the
rims of the lateral walls of the carrying structure 12 are shaped in order to
direct towards the median plane 24 of the carrying structure 12 the discharged
air of the winding path formed between the lateral walls of the structure 12
1o and the rear surface 56 of the reflectors.
Naturally diverse variations are possible without departing from the framework
of the invention.
1s An embodiment variation is presented on Figure 5. When the structure
exceeds a certain length (for example 1 meter), the thrust exerted by the air
coming out of the slot 66 and arriving at the cylindrical tube 36 may cause
deformation of the tube 36. To avoid untimely displacement of the emission
focus, one may arrange at regular intervals a maintenance loop 90 with one or
2o several spires. This loop goes round the tube 36 and through the rounded
edge 64 of the reflectors 34 and through the thickness thereof where it is
maintained a (high temperature type, ceramic type) glue plug 92.
The wire 94 of the loop 90 is of very small diameter to provide the necessary
2s flexibility (1110th mm up to approx. 10 pm). 1t is capable of resisting
temperatures greater than 900° C. The wire may be of chrome /
molybdenum,
or better of quartz fibers which are of the saure nature as the tube of the
lamp,
transparent and with a small dilatation ratio.
3o The conduit 16 forming the rear volume of the carrying structure may be of
rectangular section, as specified in the embodiment, but also of any
geometrical shape, for example circular, ovoid or square.
The carrying structure 12 may be formed of any metal or compound material
CA 02383813 2002-03-O1
17
s exhibiting the requested mechanical, electric and thermal behavior
characteristics.
The conduit 16 may be isolated from the carrying structure 12 and added
thereon, which enables to form the conduit 16 of a material different from
that
1o of the structure 12. The carrying structure may thus have for example an H-
shaped section, with a recess for the irradiating means, and a recess for an
added-on tubular conduit of duroplastic material. In such a configuration, it
is
useful to provide maintenance flanges of the conduit which do not form too big
thermal bridges between the structure and the conduit.
1s
The form of the concave reflection surface formed by both reflectors 34 may
be, seen in a plane perpendicular to the axis of the tube, a parabola whereof
the focus would be the axis of the cylindrical tube. The tube 36 may be
slightly
offset with respect to the focus of the concave surface. The reflectors 34 may
2o also take a shape close to that of an ellipse or a parabola, for example a
broken shape formed by of the arcs of circles andlor the line segments.
Besides, for manufacturing purposes (surface treatments), the length of the
reflectors 34 may not exceed a certain size. To obtain a structure 12 of large
2s dimension (for example several meters), it is possible to lay out abutting
sections of reflectors thereby providing a homogeneous longitudinal reflection
surface.
The emission method of the radiation is not so restrictive. For example, the
30 lamp of the emitter may be either filled with a low pressure gas such as
Neon,
or fitted with an axial filament aligned on the focal line and emitting in the
infrared and/or the visible range, thereby replacing the plasmatic cylinder.
The
quartz tube may be replaced with a glass tube. The tube may not be rigorously
cylindrical.
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18
The mouth 20 for supplying the conduit with fluid may be placed in one of the
externat plugs, in the longitudinal axis of the carrying structure. 1t may
also be
laid out on a lateral surface. 1t may also be positioned halfway between the
longitudinal ends of the conduit, which involves naturally in this case a
lo distribution that is difFerent from the orifices.
According to another variation, the emitter 32 may be water-cooled and the
cooling fluid through the slot 66 is an anti-oxidizing inert gas,
significantly
nitrogen.
