GB2059146A - Electric discharge lamp - Google Patents

Abstract

The present invention provides an electric discharge lamp for irradiation purposes, comprising a discharge vessel which is permeable to ultra-violet radiation, electrodes arranged therein, a noble gas filling and a buffer gas or buffer vapour, wherein the discharge vessel contains a medium absorbing outside of the range of from 320 to 350 nm, as well as one or more elements or compounds thereof which emit an intensive radiation in the range of from 320 to 350 nm. As is particularly described, the absorbing medium comprises vaporised thallium iodide and the emitters of radiation in the 320-350 nm range are one or more of indium, gallium, or the halides thereof, or iron, nickel or manganese or compounds thereof. A number of specific examples are given.

Description

SPECIFICATION Electric discharge lamp The present invention is concerned with an electric discharge lamp which can be used not only for general irradiation purposes, for example for healthpromoting and cosmetic irradiations, but also for the therapy of skin diseases, for example psoriasis or acne.

It is known to use ultra-violet irradiation to achieve health-promoting and cosmetic effects, as well as healing effects in cases of skin diseases by phototherapeutic and photochemotherapeutic methods.

Especially in the case of the treatment of the various forms of psoriasis, considerable improvements can be achieved by phototherapy and photochemotherapy.

Photochemotherapy is a combination therapy which is based upon the use of a medicament as a photosensitiser, followed by irradiation, mainly in the long-wave ultra-violet range (Wolff etal., Dtsch.

Med. Wschr., 124,247111975).

In the case of phototherapy, which is generally known as selective phototherapy, the therapeutic effect is initiated, without medicinal sensitisation, by the direct attack of energy-rich ultra-violet irradiation (UV-D/C) on the genetic material (Tronnier etal., Akt.

Derm., 349/1977; Schropl, Dt. Dermatologie,25, 499/1977).

However, success is also to have been achieved by irradiation with long-wave ultra-violet irradiation (Tronnier, Akt. Dermatol., 4, 213/1978).

Various irradiation devices are known for these types of therapy, for example those disclosed in Federal Republic of Germany Patent Specifications Nos. 2,707,920; 2,707,908; 2,609,273 and 2,616,892.

The emitters used today are not only special low pressure fluorescent lamps but also especially xenon high pressure lamps and/or mercury vapour high pressure discharges, as well as discharges in halogen-metal vapours, for example iron-gallium iodide or gallium-indium-samarium-lead iodide, as described in Federal Republic of Germany Patent Specification No. 2,531,876, and iron-manganese iodide as described in Federal Republic of Germany Patent Specification No. 1,801,834.

An analysis of the results with regard to the optimum spectral range for most purposes of irradiation showed that this extends from 320 to 350 nm, the range from 320 to 330 nm having the greatest importance. If this favourable spectral range is filtered out by appropriate filters, then, however, with the previously known sources of light and radiation, only low irradiation strengths are obtained so that, in practice, the use of conventional lamps does not give much promise of success.

Therefore, for the utilisation of the abovementioned spectral range, the elements copper and silver are also employed, the resonance lines of which at 324.8 or 328.1 nm, respectively, make possible a very effective production of irradiation.

However, a disadvantage of such lamps is that it is difficult to control the two elements copper and silver in a high temperature discharge since they have a tendency to diffuse out of the discharge column and to deposit in elementary form on the vessel wall.

It is also known to use the element lutetium for the production of irradiation in the desired wavelength range. However, because of the multi-line structure, the spectra produced therewith not only display a high proportion of energy at 320 to 350 nm but also below and above this range which, for special purposes, make it necessary to suppress broad spectral ranges by filtering.

It is an object of the present invention to provide a source of irradiation with a superior emission in the therapeutically and cosmetically favourable spectral range above 320 nm.

A further object of the present invention is to provide an electric discharge lamp of high capacity concentration which, in the wavelength range above 320 nm and especially of 320 to 330 nm, emits especially large amounts of energy.

These objects are achieved when the discharge vessel contains a medium which absorbs the radiation outside of the range of 320 - 350 nm.

Thus, according to the present invention, there is provided an electric discharge lamp for irradiation purposes, comprising a discharge vessel which is permeable to ultra-violet radiation, electrodes arranged therein, a noble gas filling and a buffer gas or buffer vapour, wherein the discharge vessel contains a medium absorbing outside of the range of from 320 to 350 nm, as well as one or more elements or compounds thereof which emit an intensive radiation in the range of from 320 to 350 nm.

The starting point of the present invention is vapourised thallium halides. Thus, we have found that the permeability of these vapours to ultra-violet radiation is highest in the wavelength range of 320 to 350 nm. In particular, radiation of lower wavelengths is considerably weakened when passed, for example through thallium iodide vapour.

Therefore, thallium halide vapours can be utilised, together with other elements or compounds and preferably halides which emit radiations in the spectral range of from 320 to 350 nm, for the production of narrow-band ultra-violet spectra.

This principle can be especially simply used in high pressure irradiators, for example with mercury as the buffer vapour, which have wall temperatures of about 1000or. and which contain considerable amounts of thallium halide in a vaporous state.

If the discharge vessel contains further additives which vaporise at such wall temperatures, such as indium or an indium halide and/or cadmium or a cadmium halide, which emit radiation in the interesting wavelength band of 320 to 350 nm, then, due to the filter action of the thallium halide vapours, an excellent emission can be achieved in this range and especially in the range of the highest permeability of 320 to 330 nm.

In addition to the above-mentioned elements indium and cadmium, use can also be made of elements which are known to be suitable for irradiations with therapeutic or cosmetic effects, such as iron, nickel and/or manganese and/or compounds thereof.

The following Examples are given for the purpose of illustrating the present invention: Example 1 A discharge vessel of silica glass or ultra-violetpermeable ceramic with an inner diameter of 12.5 mm. and an electrode distance of 25 mm. contains a filling of 4000 Pa argon, 27 mg. mercury, 0.5 mg.

thallium iodide and 0.5 mg. indium iodide.

After a warming-up time of 15 minutes on a 220 V mains supply with an appropriate connecting device, a power of 250 W was obtained at a voltage of 115 V on the radiator. The emitted radiation contains the energy of the lines of the mercury, thallium and indium but, because of the absorption in the thallium iodide vapour, displays a preferred emission at 323 nm due to the thallium, as well as at 325.6 and 325.9 nm due to the indium. Thallium lines also appear art 351.9 and 377.6 nm which, if necessary, can be narrow band filtered out or, however, can initiate favourable reactions as energy in the field of direct pigmentation.

Example 2 A discharge vessel as described in Example 1 contains a filling of 4000 Pa argon, 27 mg. mercury, 0.5 mg. thallium iodide and 1 mg. cadmium iodide.

On the same connecting device as mentioned in Example 1, in the case of a radiator voltage of 115 V, there is obtained a power of 250 W. The preferred emission lies at the wavelengths occupied by the thallium lines, as well as at 325.3 and 326.1 due to cadmium.

Example 3 A discharge vessel of silica glass or ultra-violetpermeable ceramic with an inner diameter of 22 mm.

and an electrode distance of 85 mm. contains a filling of 2500 Pa argon, 45 mg. mercury, 1.2 mg.

thallium iodide, 2 mg. indium iodide and 2 mg.

cadmium iodide.

After a warming up period of 15 minutes, on a 220 V mains supply with an appropriate connecting device, a power of 1 KW was obtained at a voltage of 115 V on the radiator. Due to the radiation of the thallium, indium and cadmium, with simultaneous weakening of the radiation of smaller and greater wavelengths by the thallium iodide vapour, good possibilities are provided for such radiators to be employed for the phototherapy of skin diseases.

Claims (7)

1. An electric discharge lamp for irradiation purposes, comprising a discharge vessel which is permeable to ultraviolet radiation, electrodes arranged therein, a noble gas filling and a buffer gas or buffer vapour, wherein the discharge vessel contains a medium absorbing outside of the range of from 320 to 350 nm, as well as one or more elements or compounds thereof which emit an intensive radiation in the range of from 320 to 350 nm.

2. An electric discharge lamp according to claim 1, wherein the medium absorbing outside of the range of from 320 to 350 nm is a thallium halide.

3. An electric discharge lamp according to claim 2, wherein the thallium halide is thallium iodide in a vaporised state.

4. An electric discharge lamp according to any of the preceding claims, wherein the compound in the discharge vessel emitting in the range of from 320 350 nm is a halide.

5. An electric discharge lamp according to any of the preceding claims, wherein the element emitting radiation in the range of from 320 to 350 nm is indium and/or cadmium.

6. An electric discharge lamp according to any of the preceding claims, wherein the discharge vessel also contains iron, nickel and/or manganese and/or compounds thereof.

7. An electric discharge lamp according to claim 1, substantially as hereinbefore described and exemplified.