FR2732181A1 - Radiation projector for quartz glass-halogen type lamp - Google Patents

Abstract

The projector (5) consists of one or more elongated radiation sources (6) esp. of quartz-glass halogen type backed by a reflecting surface (10) and radiating through a substantially plane or slightly convex transparent front face (2). The edge (4) of the front face are straight and the transparent material extends to them. The rearward support (9) for the reflecting surface is combined with the front face in one sealed unit and may be mfd. from the same material in one piece of tubular form.

Description

RADIATION PROJECTOR
AND RADIANT PANEL
The invention relates to a radiation projector and the panel made of the assembly of several projectors. The projector has as source of radiation in particular silica glass and halogen lamps, UV lamps, silica tubes at medium temperature, etc ...

 Radiation projectors are intended to distribute most of the radiation emitted by the source over a surface opposite the projector. They most often associate a reflector with the radiation source.

 The radiant panels group together several projectors, they are generally intended to irradiate large areas, often several square meters, in order to heat them, dry them, cause polymerization, etc.

 The function of radiant panels of the type of those of the invention is to obtain a uniform distribution of the energy emitted, in the range of wavelengths characteristic of the chosen source.

 The projectors of the invention are more particularly of the type using sources of elongated shape with electrical connection at both ends.

 Panels of the previous type have been described, for example, in French patent application FR 1 509 642. There are described therein described several silica glass tubes inside which an electrical resistance is the source of infrared radiation. Several rectilinear tubes are associated parallel to each other to form a radiant plate, this comprises two flat faces of silica glass connected by partitions perpendicular to the faces and made of the same material. The heating tubes are inserted between two parallel partitions. Such radiant plates made in one piece necessarily have limited dimensions and the technique for producing panels of the invention will make it possible to combine them.

 In another document, US Pat. No. 3,627,989, the assignee of which is the Applicant Company, a set of active radiant tubes (with inside heating resistors) is presented associated with passive tubes indirectly heated by the former in boxes. which include less than a dozen tubes. The goal is to widen the range of wavelengths emitted by the box, the active tubes which emit infrared of shorter wavelength heating the inactive tubes which - remaining at lower temperature emit a radiation of greater wave length.

 Boxes of the previous type provide radiation fairly uniformly distributed over the irradiated surface and which has a wide spectrum of wavelengths, but a major drawback of this type of box is the difficulty in cleaning the installation when it has been soiled by industrial use.

 Indeed, projectors and radiant panels are often used in polluting environments: paint booths, drying ovens for various solvents, laboratories in the food industry, etc. In these environments, radiant tubes or their transparent protective plate get dirty and their external surface becomes absorbent for the radiation emitted, which makes them less and less effective.

 The invention sets itself the task of providing radiation projectors which are easy to manufacture, whose focusing is simple to adjust or requires no adjustment and which are easy to maintain.

 It is also an object of the invention to provide radiant panels associating several projectors, which emit uniformly distributed energy and which are easy to maintain.

 The invention provides a radiation projector comprising at least one radiation source of elongated shape, in particular a lamp of the silica-halogen glass type, a reflective surface behind the radiation source and a front face transparent to radiation in which the front face is substantially planar or slightly convex with its rectilinear edges and in which the transparent material which constitutes this front face extends to the said rectilinear edges. Preferably, the front face and the support of the reflecting surface at the rear constitute a sealed assembly, in this case, advantageously, the front face and the support of the reflecting surface at the rear are made of the same material in one tubular shaped part.

 A simple way of carrying out the invention consists in that the front face, the support of the reflecting surface as well as the power supply supports constitute a sealed sealed assembly, with a bare filament situated inside, the filament constituting the radiation source.

 In a variant of the invention, the radiation source is a lamp made of halogen silica glass and the material of the tubular form, also made of silica glass. Preferably, the reflecting surface on the back is a layer of gold deposited on the transparent material.

 Thus the product of the invention is a radiation projector which is simple to produce with an easy or even superfluous adjustment of the focus and easy to maintain.

The invention also provides a method for manufacturing a radiation projector, it comprises the following steps
manufacture of a tubular element of transparent material, the section of which has substantially the shape of a half-oval,
* coating on the curved part of the tubular element, with a reflective layer,
cutting the tubular element into sections,
* installation at the ends of the sections of sockets which support and electrically supply the elongated radiation source, the order of the steps of the process being able to be modified.

 In a variant, two sources of radiation are associated in the extension of one another, the socket of one being associated with the socket of the other.

 The method of the invention is particularly economical because it is very simple to implement.

 The invention also proposes to use the radiation projector by associating it with other structures, in particular with identical projectors to constitute panels in which the substantially planar or slightly convex transparent front face of a projector forms with the face before the neighboring structure (s) a continuous surface without change in level. Preferably, the projectors comprise sockets which support and electrically supply the radiation sources and it is these which serve to mechanically assemble, at least partially, neighboring projectors to form the radiant panel.

 Advantageously, when two or more projectors are in the extension of one another, they have a front face in one piece.

 The panels of the invention are very easy to clean since their front face is continuous, has little or no relief. They are also easy to assemble thanks to the use of multiple-function sockets, electrical and mechanical.

 The drawings and the description which follow will make it possible to understand the invention and to appreciate its advantages.

FIG. 1 represents a panel of the invention seen from the front,
FIG. 2 is a section perpendicular to the axis of a radiation projector,
FIG. 3 the junction of two projectors,
Figures 4 and 5, two other examples of association of projectors
FIG. 6 shows a section through a socket supplying a source of radiation,
FIG. 7 represents two projectors constituting sealed assemblies with bare filament and,
FIG. 8, a section through one of the projectors of FIG. 7.

 Often, we need sources of radiation that can evenly irradiate a surface. This is most often the case for drying operations, for example in the paper industry. Depending on the case, depending on the energy to be supplied per unit area and per time unit, depending on the nature (spectral characteristics) of the material, various sources of infrared radiation are used for drying.

 For longer wavelengths, greater than 1.5 lim (medium infrared), quartz tubes are used with filaments in the open air inside.

These sources generally have their maximum energy at 2.7 lim. We have seen that document US 3 627 989, of which the Applicant is the holder, proposes a technique for extending the field to longer wavelengths through the use of passive radiators indirectly heated by the active tubes and therefore at temperatures lower. The invention relates inter alia to radiant panels using tubes whose emission occurs in the middle infrared.

 For shorter wavelengths with their spectral maximum around 1.2 i, m and, therefore with part of the energy in the visible range (8% below 0.7 hum), we use filament lamps and halogen atmosphere in a silica glass envelope. These lamps are very powerful and therefore allow very rapid heating and drying actions. The invention is applicable to sources which are halogen lamps of elongated shape, those which generally have an electrical connection at each end. However, it also applies to sealed lamps incorporating their reflectors and the source of which is the bare filament.

In addition to the previous infrared or visible sources of radiation,
The invention also applies to all sources of radiation of elongated shape such as, for example, tubes emitting ultraviolet. Sources
UV are used for multiple applications, in particular to produce chemical reactions such as for example polymerization. If it is desired to obtain rapid polymerization over a large area, for example of a film covering a fabric, a regular distribution of the radiation is important.

 The technique of the invention applies in all cases where, in addition to a uniform distribution of the radiation, it is desired to be able to easily clean the surface of the projector or radiant panel.

 In Figure 1 we see in 1 such a panel. Its front face is composed of flat or slightly curved plates 2 whose edges 3, 4 are contiguous. These plates 2 are the front faces of individual projectors 5 represented in FIG. 2 which each comprise at least one radiation source 6. In the figure a halogen-quartz tube is shown with the tube 7 made of silica glass and the filament 8. The main part of the projector 5 is constituted by the silica glass casing. This is tubular, it has, as we have seen, a front face 2, flat or slightly curved and a rear face 9 in the form of a gutter whose section is a half-oval and which is coated, generally externally d a layer 10 which reflects the radiation emitted by the source 6. In the example, it is a layer of gold which is a good reflector for the radiation of a halogen lamp. A variant of the invention provides that the reflector can be attached. It is then a sheet which surrounds the rear part of the projector 5. Either it is the sheet itself which is polished and which reflects the radiation, or else it is coated superficially with a reflective layer such as in gold .

The silica tubular casing is manufactured in very long lengths which are cut to the size of the projectors.

 In Figure 1, the components of the panel are all juxtaposed projectors. The panels of the invention generally comprise projectors which adjoin other structural elements, frames, filling surfaces between projectors, etc., the characteristic of which is to have a front face in continuity with those of projectors or neighboring structures.

 FIG. 3 shows an example of an inclined cut to make the edge 3 of the front face 2 of two aligned projectors. To make the connections of the tubes 6, a socket 11 has been installed, straddling two tubes, which is a part with multiple functions.

 Such a socket 11 is shown in section in FIG. 6. This piece mechanically assembles the different elements, the front face 2 and the support 9 of the reflecting surface 10 if they do not form a whole in one piece.

This socket 11 also generally supports a rear protective casing 12, preferably made of metal. This generally comprises fixing lugs, not shown, to immobilize the projector and the entire panel.

 The use of a tubular casing and a socket which fixes the position of the different elements present ensures that the radiation projector will provide exactly the beam that is desired. In order to guarantee the quality of a reflected beam, two things must be mastered: the shape of the reflecting surface and the position of the radiation source. Today the techniques for manufacturing tubes, even in refractory materials such as silica, provide very precise shapes. It is thus possible to give the surface 10 (FIG. 2) the desired shape so that the radiations emitted by the filament 8 are reflected in the desired direction. Indeed, the precise position of the filament 8 relative to the reflector is guaranteed by the shape of the socket 11, a stable shape thanks to the choice of material, preferably ceramic.

 The socket 11 also ensures the electrical supply of the radiation source 6. We see in the figure a spring 13 connected to a terminal 14 which allows the connection of the electrical supply circuit. The socket shown in Figure 6 is located at the free end of a projector 5. When the socket is located between two elements 5 as in Figure 3 it is double. Most often, at the rear, the socket 11 ends by a part 1 5 in the form of a cylinder of revolution which simplifies the machining of quartz tubes since a simple circular drilling is sufficient. It is also provided when no problem of cooling the ends of the radiation sources arises (which is unfortunately not the case today with quartz-halogen tubes), that the same tubular element can be extend to two spotlights located end to end. The front face is then - unlike Figure 3 - continuous and the rear drilling allows the introduction of a double socket 11 which is rigidly fixed to the rear face of the tubular element for example by clipping and which thus gives the sources radiation 6 a precise position relative to the reflector 10.

 In FIGS. 4 and 5 are represented, seen from the front, other techniques for assembling projectors 5 to constitute elements of radiant panels 1. In the two cases, shown, the silica glass tubes do not have contiguous front faces. It is therefore possible here to fix the radiant panel 1 from the front face by means of the sockets 11 through which holes are drilled to introduce screws, pegs or rivets.

 With the configuration of Figure 4, it is also possible to cut the tubes 5 so that their front faces 2 meet and then cleaning the front face of the entire panel 1 is greatly facilitated. On the other hand in FIG. 4, it can be seen that the efficiency of the reflector system at the rear of the tube is less great.

 The system shown in FIG. 5 prevents the less illuminated central area, in the space corresponding to the junction of the ends of the modules, from being too wide.

 Figures 7 and 8 relate to a type of projector whose particularity is to have only one envelope inside which is the source of radiation, generally thermal. In the case of a filament heated by the Joule effect such as tungsten for example, the latter is bare, supported by the usual means not shown. The atmosphere of the whole is preferably based on halogen gas.

 The projector is made from a single sealed enclosure. The front face 31 is preferably inscribed in a rectangle, it is slightly curved, of cylindrical shape as can be seen in FIG. 8, it is advantageously made of transparent vitreous silica.

 The rear face 32 is also cylindrical, the cross section of the cylinder 33 preferably being parabolic.

 We see in Figure 7 that the front face 31 is longer than all the other parts of the projector. When the projectors are combined to form a radiant panel, the front faces of the projectors constitute a continuous surface.

 At the ends of the projector, there is seen at 34 a base which preferably constitutes both the sealing of the tube constituting the projector and the electrical outlet of the projector.

 This base ends with a metal ring 35 which not only has an electrical function but also that of holding and assembling the headlights by means of parts not shown which play the same role as the sockets 11 of FIGS. 3 to 6.

 In Figure 8, there are shown two light rays 36 which after being emitted by the filament 30 are reflected by the reflecting surface 37, preferably based on gold. This surface is shown on the internal side of the rear face 33. It is protected there, protected from scratches and any degradation. But it is obvious that the optical effect is little different if the reflective layer is on the external side of the rear face 33 of the projector. This configuration may be preferred, in particular for manufacturing reasons.

 In the case of halogen lamps which emit part of their energy in the visible range, it may be advantageous to reduce this emission. In this case, the front faces 2 and 31 of the modular elements 5 are covered, preferably internally, with a coating absorbing visible light, for example of dark red color. The same effect can be obtained by using a mass-colored material for the front face.

 The above description mainly focuses on near infrared radiation sources which are quartz tubes with halogen atmosphere. In this case, the material of the tube 5 and of the face 31 is essential, it must be transparent to the radiation emitted, for example it will be silica glass.

But it is obvious that with other sources of radiation, other materials such as ordinary glass or certain plastics (polycarbonate, polystyrene-shock) can also be used to carry out the invention.

 The projectors of the invention with their optical properties: precision of the reflecting surface and good focusing thanks to the precise position of the source, distant from the reflector, make it possible to distribute the radiation uniformly over a large area with a reduced number of projectors.

 If, for example with a panel like the one in Figure 1, moderately heat a surface opposite, there will be a choice between two solutions: or equip all the projectors of the panel with IR tubes of great length wave and medium energy, or equip one row of projectors on three, 21, 22, 23 with more powerful quartz-halogen tubes and leave the intermediate spaces 24, 25, 26, 27 without projector, with only one plate to ensure the continuity of the front face. The optical design of the cylindrical source-mirror-surface to be illuminated system being studied to ensure uniform heating.

 The design of the unit projectors with rectilinear edges on their front face which define a surface of which no material element of the projector overflows makes it possible to easily connect the front face of the projector to other flat or slightly curved surfaces such as those of a supporting structure. of the projector or like the surfaces of the front faces of the other projectors of a panel.

 This design makes it possible to provide for the space between two rectilinear edges to be filled with a tight seal, for example made of silicone sealant or the like. We then obtain a projector or a panel bringing together several projectors whose facade is perfectly waterproof and easy to clean.

Sealing is indeed ensured, not only between the front face and the reflector in the case where they are made in one piece, but also between the front face and the structure which adjoins it: other front face or support element of the projector.

Claims (11)

 1. Radiation projector comprising at least one elongated radiation source, in particular a lamp of the silica-halogen glass type, a reflecting surface at the rear of the radiation source and a front face transparent to radiation, characterized in that its front face is substantially flat or slightly convex, in that its edges are rectilinear and in that the transparent material which constitutes it extends up to said rectilinear edges.  2. Projector according to claim 1, characterized in that the front face and the support of the reflecting surface at the rear constitute a sealed assembly.  3. Projector according to claim 2, characterized in that the front face and the support of the reflecting surface are made of the same material in a single piece of tubular shape.  4. Projector according to claim 3, characterized in that the front face, the support of the reflecting surface as well as of the power supply supports constitute a sealed sealed assembly, in that a bare filament is located inside and in that it constitutes the source of radiation.  5. Projector according to claim 3, characterized in that the radiation source is a halogen silica glass lamp, and in that the material of the tubular form is also made of silica glass.  6. Projector according to claim 4 or claim 5, characterized in that the reflecting surface at the rear is a layer of gold deposited on the transparent material.  7. Method for producing radiation projectors according to one of claims 1 to 3, characterized in that it comprises the following steps  - manufacture of a tubular element of transparent material, the section of which has substantially the shape of a half-oval,  - coating on the curved part of the tubular element, with a reflective layer  - cutting of the tubular element into sections  - installation at the ends of the sections of sockets which support and electrically supply the elongated radiation source.  8. Method according to claim 7, characterized in that two radiation sources are associated in the extension of one another, the socket of one being associated with the socket of the other.  9. Use of the projector according to one of claims 1 to 6 in the production of a radiant panel in which the substantially planar or slightly convex transparent front face of a projector forms with the front face of the structure (s) next to a continuous surface without change in level.  10. Use according to claim 9, characterized in that the projectors comprise sockets which support and supply electrically the radiation sources and in that it is these which serve to mechanically assemble neighboring projectors to form the radiant panel.  11. Use according to claim 9, characterized in that two or more projectors in the extension of one another have a front face in one piece.