Electric lamp and discharge devices – With optical device or special ray transmissive envelope
Reexamination Certificate
2000-06-21
2003-06-24
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
With optical device or special ray transmissive envelope
C313S113000, C313S493000, C313S634000, C250S50400H, C362S268000
Reexamination Certificate
active
06583535
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a tube emitting electromagnetic radiation, made of a transparent non-fluorescent material, in particular a glass-based or quartz-based material, and having a straight structure drilled from end to end by a bore elongate around an axis so as to confine a housing designed to contain a radiation-emitting filament or plasma bundle.
It also relates to a device and a method implementing such a tube.
The invention finds a particularly important, although non-exclusive, application in the field of photochemical treatment of materials by ultraviolet radiation with emitting tubes containing an ionized gas, the pressure of which gas depends on the concentration of plasma inside the tube, used for example in the sterilization field, the paper industry, textiles, the wood and plastic materials industry, the food industry, the automobile industry and the printing field, in particular for polymerization of inks or varnishes on films, for example formed by supports in the form of reels of paper or cardboard, or supports made of metallic material such as aluminium or copper foil or steel strip, or supports made from synthetic material such as plastic products, PVC, polyethylene or other, or supports made of natural, recomposed or synthetic wood, or even electronic circuitry or any other support.
Another application is in the infrared field.
The invention is not limited to the types of products to be treated. It can for example be used for drying of products in plate form, for drying of certain varnishes and adhesives, for drying of wire-based products extending elongate around an axis, or for sterilization of liquid products in the form of a sheet or of a column around an axis.
STATE OF THE PRIOR ART
Glass tubes emitting ultraviolet or infrared rays comprising a cylindrical bore are already known. These tubes in general associated to concave reflectors of parabolic or elliptic cross sections present drawbacks. They present large dimensions, are cumbersome and are not of optimum efficiency.
Most devices of the prior art in fact essentially describe separate emitters/reflectors implementing a distribution of the radiation emitted by a bundle or a filament according to two embodiments, i.e. primary rays which are emitted from the source in a divergent flux, and secondary rays which, being emitted from the source, are reflected on a surface presenting a cross section in the form of a mathematical curve to reach the irradiated plane in a convergent or parallel flux.
In all cases, and by structural defect of the system, the primary rays therefore do not have the same optimized trajectory, and consequently the same efficiency, as the secondary rays.
The document U.S. Pat. No. 3,885,181 describes a high-pressure sodium lighting lamp designed to emit rays in the visible field. It comprises a tubular discharge enclosure, made of an alumina-charged polycrystalline material. It has a non-circular cross section for an asymmetric polar distribution of the light emitted by the lamp. The emitting source is diffused from a luminous surface, and its plasma section is imposed by the internal geometry of the enclosure. The radiating source is not pin-point and the lamp is not equipped with a reflector or a monoblock emitter/reflector. Such a lamp is used for public lighting or for traffic signals.
The document U.S. Pat. No. 2,254,962 relates to an optic device composed of a cylindrical lens having a central refraction surface and a reflector with additional elliptic reflection and refraction surfaces of the same virtual focal spot. The light source is distinct and is housed in a semi-open notch, being dissociated from the reflector, which cannot restitute the whole of the radiation. The walls of the notch are arranged in such a way as to obtain divergent fluxes in the lens when passing the dioptric planes formed by the edges forming the confines of the notch. Such a device does not constitute a longitudinal monoblock emitter/reflector able to recover the whole of the emitted radiation over 360°.
OBJECT OF THE INVENTION
The object of the present invention is to provide a radiation-emitting tube, a device and a method implementing such a tube, meeting the requirements of practice better than those known in the prior art.
A first object of the invention is to achieve a compact tube which is not cumbersome, able to render the primary and secondary rays homogeneous, complementary, and directed in the same direction towards the irradiated product, in order to optimize the usable photochemical, photothermal and/or photoluminous radiating energy.
A second object of the invention consists in recovering the whole of the spatial radiation emitted by an electromagnetic emitting tube to increase the focusing and the energy efficiency.
The invention stems from the idea of giving the bore an appreciably square or rectangular cross section, at least two opposite sides of which are of a cross section in the form of a convex curve, so as to obtain parallel fluxes when passing the dioptric planes formed by said sides.
What must be understood here by convex is an internal convex curve whose peak is directed towards the axis of the bore.
What must be understood here by appreciably square or rectangular is a four-sided figure inscribed in a square or a rectangle, said sides being in an arc of a circle with large radii of curvature, i.e. for example R>10 mm.
To do this the centre of the plasma bundle, or the irradiating filament, is arranged to be at the centre of the geometric optics of said dioptric surfaces.
Thus the convex dioptric surfaces of the bore modify the divergent radiating flux from the geometric centre of the convex curves to form a flux which is parallel or appreciably parallel, in the transparent solid medium, then parallel or even convergent towards the plane to be irradiated, in combination with the dioptric output surface of the tube and/or a reflecting surface of the emitted rays situated on the side walls, on each side, for example symmetrically with respect to the axial plane of the bore.
The tube according to the invention is characterized in that the bore is of appreciably square or rectangular shaped cross section at least two opposite sides of which are in the shape of convex curves, said sides forming dioptric surfaces arranged to modify the direction of the rays emitted from the filament or from the axis of the emitting bundle to make them parallel or appreciably parallel in the transparent solid medium of the glass.
By obtaining parallel rays in the transparent medium, subsequent treatment of the rays is rendered considerably easier. Proliferation of the rays is also reduced achieving in particular an excellent power density in the case of focusing, and enabling limiting of the divergent rays to be achieved in the case of parallel flux irradiation.
In an advantageous case, the sides of the bore are respectively symmetrical with respect to the planes of symmetry of the square or of the rectangle, the direction of the rays being appreciably parallel to that of a plane of symmetry of the square or of the rectangle of the bore.
In the embodiments more particularly described, the present invention implements a straight emitting tube whose geometric centre of emission is merged with and identical to the focal spot of a corresponding reflector, which is also straight and of at least partially flat or appreciably flat cross section to treat flat surfaces, or of at least partially inverted parabolic cross section to focus the radiation, the generating line at the peak of the curve of the reflector being parallel to the axis which is merged with and identical to the focal line, and the end edges of the straight or inverted parabolic portions being situated below the axis of the bore, on the other side of the latter with respect to said generating line at the peak.
By inverted parabola we mean the reflection curve which transforms the parallel flux into a convergent flux focused on a line.
More precisely the ultraviolet, and/or visible, and/or infrared
Day Michael H.
Hodges Matt
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