US3179794A - Device for simultaneously producing luminous and sterilizing radiations - Google Patents

Description

Aprll 20, 1965 M. WALY 3,179,794

DEVICE FOR SIMULTANEOUSLY PRODUCING LUMINOUS AND STERILIZING RADIATIONS Filed July 20, 1962 INVENT OR MOUS TAPHA W4 L Y United States Patent DEVICE FOR SIMULTANEOUSLY PRODUCING LUMINOUS AND STERILIZING RADIATIONS Moustapha Waly, Geneva, Switzerland, assignor to Anicet Anstalt, Vaduz, Liechtenstein, a corporation of Liechtenstein Filed July 20, 1962, Ser. No. 211,249 1 Claim. (Cl. 24051.11)

This invention is concerned with simultaneously producing visible light and sterilizing radiation, and with a device constituting jointly a lighting lamp and a source of sterilizing radiations.

Sterilizing radiation devices are already known which act as germ-killing, bactericidal, microbicidal or like lamps. These lamps are based on the principle consisting in emitting a relatively large quantity of ultraviolet light. This emission is caused by an electrical discharge in a closed vessel consisting for example of a quartz tube in the presence of rarefied atmosphere consisting of mercury vapor with traces of rare gases; this discharge strikes an are between two electrodes which emits strong radiations in the ultraviolet range of the electromagnetic spectrum.

The predominant ultraviolet radiation emitted by such a low-pressure mercury vapor .arc corresponds to the spectrum line of 2537 A. wavelength and about 90% of the electrical energy absorbed by the discharge tube is converted into radiation of same wavelength. The monochromatic rays of this emission exert substantially a maximum destructive effect on bacteria, ferments and mold in the ultraviolet region as determined by Barnerd and Morgan, and also by Gates.

These germ-killing tubes having a bulb made of special glass, forgexample of quartz, are transparent to the aforesaid germ-killing radiation. However, they still allow therethrough certain radiations of a wavelength inferior to 2537 A. whose effect is to produce by photosynthesis a controlled quantity of ozone suitable for use for disinfection and deodorization purposes.

As a rule, these lamps are energized through an autotransformer equipped with a current limiter consisting for example of a reactance coil called ballast and which is necessary since the tubes have negative characteristics. The aforesaid autotransformer is connected to the normal ll0-volt or 220-volt mains. The lamps are generally mounted in electric brackets, wall-fittings or ceiling-fittings and installed in the rooms or spaces to be protected, disinfected or deodorized. They lend themselves to many applications, for example in rooms for preparing, conditioning and packing pharmaceutic products, in hospitals, in operating theatres, in refrigerated rooms for storing foodstuffs (notably fish and meat), in shops, in workshops and also in stables, cattle-sheds, incubators, etc. As the light produced by these lamps in the visible portion of the spectrum is very weak, it is generally necessary to associate conventional lighting lamps or bulbs thereto, such as ordinary incandescent bulbs or fluorescent tubes.

It is the object of this invention to avoid this drawback by combining in a single device the source of visible light and the source of sterilizing ultraviolet radiation, so that the device constituting the subject-matter of this in vention becomes accessible to the individual, thereby enabling anybody to use the germ-killing device practically anywhere. To this end, this invention is remarkable notably in that it consists in utilizing at least one portion of the aforesaid ultraviolet rays for exciting the photoluminescence of phosphor-forming fluorescent substances or the like, arranged in close vicinity of the aforesaid source of rays.

According to another feature of this invention, the aforesaid ultraviolet rays are produced by striking electric arcs in mercury vapor, as already known per se, the loss Patented Apr. 20, 1965- ICE of power being used on the one hand for limiting the strength of the electric current and on the other hand for producing by incandescence, by Joule eifect, a visible light which adds itself to the light produced by photoluminescence and compensates the color of the light produced by the arc.

This inventionis concerned with a device constituting both a lighting lamp and a source of sterilizing radiation for carrying out the method set forth hereinabove, of the type comprising a source aforesaid of ultraviolet rays, consisting of at least one low-pressure mercury-vapor arc tube, this device being remarkable notably in that it comprises a screen surface or the like, which may be opaque, having substantiallythe shape of a reflector with the concave or active face thereof coated with a layer of photoluminescent phosphor-producing substances of which the maximum excitation photosensitivity corresponds substantially to a 2537 A. wavelength, the aforesaid source of ultraviolet radiation being arranged in the vicinity of said photoluminescent surface.

According to another feature of this invention the aforesaid source of ultraviolet rays is fed through at least one static booster-transformer of a type already known per se, of which the current strength is limited by one or more dead resistances constituting preferably the heated filaments of incandescent lighting bulbs arranged for example symmetrically in relation to said source in the vicinity of said photoluminescent surface.

. With this arrangement, the ballast-forming reactance coil, which is a rather heavy, cumbersome and costly component element, may be dispensed with and replaced by a transformer the current of which is limited by ohmic resistances constituting the incandescent filaments of conventional lighting bulbs. The lighting and sterilizing apparatus thus obtained is extremely compact, light in weight, simple to manufacture and of relatively low cost.

Other features and advantages of this invention will 7 appear as the following description proceeds with reference to the accompanying drawing, in which:

FIGURE 1 shows the basic principle and the wiring diagram of an apparatus constructed according to the teachings of this invention;

FIGURE 2 is a diagrammatic axial section showing a typical embodiment of the apparatus, and.

FIGURE 3 is a diagrammatic plan view from below of the device of FIGURE 2.

In the form of embodiment illustrated by way of example in the drawing, the device comprises at least one ultraviolet ray generating tube 1 in which an electric dis charge in the form of an arc takes place in a low-pressure mercury vapor atmosphere between two opposite electrodes 2, 3. To this end, the tube has its electrode connected to the secondary winding 4 of a static boostertransformer 5 having its primary winding 6 connected through a switch 7 to a source 8 of electric alternating current, consisting for example of the usual mains. Adjacent to the tube 1 is a preferably opaque screen or like member 9 having its inner face coated with a layer 10 of fluorescent substances or adequate phosphors adapted to transform the 2537 A. radiation of adequate wavelength into visible light.

The useful current strength in the tube is advantageously limited by one or more dead resistances such as 11, interposed in series in the electrical circuit. These dead resistances may advantageously consist of the filaments, for example of refractory metal such as tungsten, of incandescent lamps, for example in the form of glass bulbs either evacuated or filled with chemically inert gas like conventional lighting bulbs and containing a filament heated by Joule effect.

These incandescent bulbs 11 may be either interposed in the circuit of tube 1 in series with the secondary winding 4 of transformer 5, or preferably in the circuit of the primary winding e of transformer 5, as illustrated in FIG- URE 1, which is advantageous in that conventional lowvoltage lighting bulbs can be used.

FIGURES 2 and 3 illustrate a typical embodiment of the device wherein the screen 9 is preferably in the form of a reflector having a substantially symmetrical configuration, for example as a nearly prismaticsurface. The source of ultraviolet rays 1 is disposed in the centralregion of the reflector and in the vicinity of its reflecting surface, substantially in the plane of symmetry thereof, and the incandescent bulbs 11 of which for example two or an even number are provided, are disposed symmetrically on either side of this plane, also in the vicinity of the fluorescent surface. g

An elongated aperture or slot 12 is formed in the support 9 constituting a luminous lamp-shade or reflector, preferably opposite the source 1 of ultraviolet rays, the

.size of this aperture being at least equal to the size of said source. This aperture 12 acts as a ventilating shaft and is adapted to evacuate the heated air resulting-from the circulation of air about the tube 1. At the same time this aperture permits the circulation of disinfected air through the room or space in which the lighting apparatus is installed.

The operation of this device is both simple and efiicient. It produces on the one hand an invisible, germ-killing radiation generated by the discharge tube or tubes 1, and on the other hand a visible light produced by the phosphors excited to photoluminescence by the 2537 A. wavelength radiations emitted by the tube or tubes 1, and finally, a visible light emitted by the incandescent bulbs 11 so that their light is added to that produced by photoluminescence and compensates the color of the light produced by the electric arc in the tube or tubes 1.

Repeated tests proved that with the device of this invention a SO-Watt light source can easily be obtained which has at the same time a strong germicidal power, in the form of an apparatus lighter and more economical than any existing fluorescent lamp devices equipped with a heavy and cumbersome ballast.

Of course, the invention should not be construed as being limited to the forms of embodiment shown, de scribed or suggested herein, which are given by way of example only.

What I claim is:

A lighting and sterilizing fixture comprising opaque reflector means formed with an internal, generally concave surface of substantially elongated shape which is arranged about a plane of symmetry extended longitudinally of said reflector means, said concave surface being coated with a layer of phosphorforming photolumincscent materials having their maximum excitation photosensitivity corresponding substantially to the 2537 A. wavelength, at least one low-pressure mercury-vapor arc tube generating ultraviolet radiation, and being located in the vicinity of, parallel with and spaced from said concave surface, with its longitudinal center line situated substantially in said plane of symmetry, said reflector means being formed with an elongated slot with outwardly projecting parallel edge flanges, having its center line located substantially in said plane of symmetry and extending in substantially registering relation to said tube, the size of said slot being at least equal to that of said tube, an even number of electric incandescent lamps arranged in spaced relationship on either side of said plane of symmetry, adjacent to and spaced from said concave surface so as to be laterally offset with respect to said slot, and a step-up transformer having a primary winding connected to an AC. supply source by the intermediary of switch means and a single secondary winding, said tube being electrically connected across the terminals of said secondary winding, whereas said lamps are electrically connected in series with said primary winding.

References Qited by the Examiner UNITED STATES PATENTS NORTON ANSHER, Primary Examiner.

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