US1917848A - Ultra-violet lamp - Google Patents

Description

ULTRA-UGLET LAMP Filed NOV. 25.5 i959 Patented July 11,1-"1933- UNITED STATES` PATENT OFFICE JOHN WESLEY MARDEN AND HARVEY CLAYTON RENTSCHLER, F EAST ORANGE, NEW

JERSEY, SSIGNORS TO WESTINGHOUSE LAMP COMPANY, A CORPORATION QF Pm- SYLVANIA ULTRA-VIOLET LAMP Application filed November 21, 1930. Serial No. @37,13%

This invention relates to a lamp for the production of ultra-violet radiation and more particularly to gaseous conduction lamps of the negative glow type having a spectrum relatively rich in ultra-violet radiation of a preferred wave length.

Heretofore in the art ultra-violent radlation has been recognized as being particularly beneficial in therapy and in thepromotion of certain bactericidal reactions. fieretoforel the greater number of available sources ot artificial ultra-violet radiation have been arc devices utilizing carbon, iron, mercury vapor, or tungsten arcs. Such devices whlle yielding ultra-violet radiation yield such radiation in relatively large quantities whlch are dicult to control and to apply and which moreover require expensive auxillary equipment to operate.

In copending application Serlal No. 437,- 659 filed March 21, 1930, by J. W. Marden et al., which application is assigned to the same assignee as the present application, there is disclosed a type of ultra-violet radiatl ing device which has been developed particularly for use in living rooms and other enclosed places where a mild source of ultraviolet radiation is desired. The J. .W. Marden of this copending application is the same J. W. Marden of the present application.

Brieiiy stated the ultra-violet radiating device of the above identified copending application comprises a negative glow dis charge device of the gaseous conduction type incorporating indirectly heated cathode assemblies and mercury vapor.

The ultra-violet lamp is arranged for use directly from a lighting circuit of 11G-220 volts by electrically connecting a plurality of such lamps in series with a suitable ballast resistance, preferably an incandescent lamp of suitable current carrying capacity, to cut down the line voltage to that which operates the glow discharge lamps.

The heater element of the cathode assemblies and the thermionically active indirectly heated sleeve members thereof are electrically connected in shunt relation so as to provide means to control the glow discharge of the device.

The combination of glow discharge device and incandescent filament lamp may be assembled in a unit and inserted in an ordinary lamp socket and allowed to burn for pro longed periods of time without the emission of deleterious amounts of ultra-violet radiation. Such a device, for example, set up 'in an ordinary living room may be operated with substantial safety and with substantial therapeutic benefit to those generally inhabiting the room.

' It has been found that certain bactericidal and other actions are materially sensitive to ultra-violet radiation of the shorter wave lengths and in particular to wave lengths approximating 2537 Angstroin. We have found that the ultra-violet lamp of the above identified copending application may be materially improved and made of great value in the application of the lamp for lspecial purposes, such as bactericidal actions, by increasing the relative proportion of ultraviolet radiation' of 2537 Angstrom emitted therefrom.

It is one of the objects of the present invention to so improve the glow discharge device of the above identified copenolng application.

It is another object of the present invention to provide an ultra-violet lamp of the negative glow discharge type having a spectrum relatively rich in ultra-violet radiation approximating 2537 Angstrom.

It is another object of this invention to provide means to limit vapor pressure of the mercury in a gaseous conduction lamp of the negative glow type..

It is another object of this invention to provide anultra-violet lamp giving a spectrum relatively rich in ultra-violet radiation of approximately '2537 Angstrom.

Another. object of this invention is to facilitate the` application of ultra-violet radiation in therapy.

A further object of our invention is to provide an ultraviolet lamp whose envelope has at least one portion thereof whose transmission factor to the ated' therein is relatively high.

Other objects and advantages will be apile ultraviolet light generparent as the invention is more fully disclosed.

Heretofore many attempts have been made to obtain ultra-violet radiation that is rich in the 2537 Angstrom line. In general it is found that radlation of this wave length is strongly absorbed by mercury vapor and while a more or less increase in the quantity of radiation of the 2537 wave length radiation has been obtained, the quantity of radiation of other wave lengths has been similarly increased in approximately the same order of magnitude.

In the device of the above identified copendin application the type of negative glow discharge obtained -therein is distinctive over prior art devices in that it is diffused or dispersed throughout the interior of the enclosing envelope rather than being localized at or around the electrode surfaces.

Heretofore arc discharge or gaseous conduction devices of the ultra-violet type have incorporated in addition to the mercury vapor a proportion of an inert or monatomic gas. rIhe higher gas pressure, even though the mercury vapor pressure within the device is maintained lovv7 as by water cooling, causes the discharge to concentrate or to localize upon the electrodes. The vapor pressure of the mercury in the region outside of the arc is still suiiicient to absorb the greater proportion of the 2537 Angstrom radiation in the discharge.

In the device of the above identified copending application the glow discharge being general throughout the enclosing envelope generates the 2537 Angstrom radiation in all parts of the device. This radiation is in part absorbed by the mercury vapor present in the device. We have found, however, that this absorption may be reduced in large measure by limiting the vapor pressure of the mercury to within certain limits (specifically between .001 to .08 m. m. of mercury) and that the ultra-violet radiation thus obtained is relatively rich proportionally in radiation of approximately 2537 An strom.

his increase in the 2537 Angstrom radiation is not of the same order of magnitude as the increase in other wave length radiation as is obtained byV prior art methods, but is of greater intensity than are the lines of the other wave length radiation and may be as much as ten times asA strong as the other wave lengths of ultra-violet radiation. This makes the lamp of particular value as a source of short wave length radiation for special therapeutic purposes.

Before further disclosing the nature and scope of the present invention reference should be made to the accompanying drawing wherein Fig. 1 illustrates in side elevational view partly lin section one type of ultra-violet radiating gaseous conduction Pdevice constructed in accordance with the present invention; and l Fig. 2 illustrates in side elevational view partly in section a smaller type of such de-` v1ce.

Referring to Fig. 1 the gaseous conduction device `of the present invention comprises an enclosin envelo e 1 having a reentrant stem 2 o the tip ess type through which extend leading in support wires Bland 4 from which are supported indirectly heated cathodes 5 and 6, the heater elements 7 and 8 (not shown) of which are electrically connected in series across the leading-in support wires 3 and 4 by means of conductor 9.

Cathodes 5 and 6 are electrically connected to leading in wires 3 and 4 by means of conductors 1() and 11 respectively. A small amount of mercury 12 is enclosed within the envelope 1. rIhe device is hi hly evacuated 1n any suitable manner throng tubulature 13 of the stem 2.

'zlhe enclosing envelope 1 is preferably comprised of material previous to ultra-violet radiation, such as Corex glass, quartz and the like. Cathodes 5 and 6 may comprise what is known in the art as oxide coated cathodes of the indirectly heated type and may be briefly -described as being comprised of a cylindrical sleeve member indicated by numerals 5 and 6 exteriorly surfaced with thermionically active alkaline earth metal compounds 14 and interiorly disposed refractory metal heater elements 7 and 8, preferably of the coil type as illustrated, and also preferably comprised of tungsten.

The sleeve member is provided with end plugs 15 comprised of refractory insulating material, such as alumina, for the purpose of assisting in centrally positioning the heater element and to facilitate the heating up of the sleeve member of the cathode by retaining the heat energy of the heater ele- Gments within the sleeve member.

The heater elements 7 and 8 of the cathodes are electrically connected in series and in shunt relation to the cathode sleeve members 5 and 6 so that when a glow discharge passes between said sleeve members the electric current conducted thereacross is by-passed from the current flowing in said heater elements.

The device illustrated in Fig. 2 is substantially identical in constructional details as the device illustrated in Fig. 1 but of smaller size and the enclosing envelope 1 may be comprisedof material either pervious or impervious to ultra-violet radiations but having a portion 16 thereof relatively more pervious to ultra-violet radiation than the remainder of the envelope. Portion 16 may comprise, for example, a bulbous thin glass Window, such as has heretofore been disclosed in U. S. Patent No. 1,735,302, issued November 11, 1929, to C. M. Slack, which Ipatent is as# signed to the same assignee as the'presentinvention. As illustrated, the window is of substantially the -same composition and)4 is homogeneously' united with vthe Imajor portionof the envelope. f1 d In accordance-with the present invention the mercury vvapor pressure of the glow dis'- charge device illustrated in Figsrl and 2 the constructional features of which have en disclosed and claimed in copending application Serial No.- 437,659 above identified,- is limited to a range of from .001 to L08 m. m. of mercury. 1^ I- ,if

In order to obtain this 4wel preferably design the device so that :the heat radiating capacity ofthe device is sufficient to main'- tain the intern-altemperatures thereof between 20 C. andv 75 C.- At vapor pressures of'mercury above approximately .O8 1n. m. of mercury the 2537- Angstrom line of ultra-violet radiation is'matrially absorbed.

In F ig. 1 the device illustrated is of relatively large heat generating capacity, the cathodes being designed to give relatively large amounts" of ultra-vio et' radiation. Accordingly the mercury 12 is collectedin a protuberance 17 having a more or less restricted opening` 18 Within theenvelope l so that there is a limited exposure oit the mercury 12 to the lheat energy liberated With inthe envelope 1 during operation of the device. As the vapor pressure' of mercury may rise to .08 n1. m. before substantial absorption of the 2537 Angstrom radiation is materially obtained, it is to be appreciated that such a mechanical means, as is herein illustrated for restricting the vaporization of the mercury Within the container or of facilitating the radiation of the heat energy of the device so that the internal temperature of the device may be maintained within the desired temperature range, will sulce `for the purposes of the present invention.

With greater heat energy inputthe construction 18 may be made relatively small. With lesser heat energy input the mercury may be left fully exposed to the heat radiation as is illustrated in Fig. 2.

There are many ways of accomplishing or of obtaining this minimum or preferred vapor pressure of mercury or of controlling the internal temperature of the device, but the method herein disclosed appears to be most expedient.

Having broadly and specically outlined the nature and scope of the present invention and given a Lspecilic embodiment thereof it is apparent that there may be many modifications and departures made of the present invention without substantially departing from the nature and scope thereof and such departures and modifications are anticipated as may fall Within the scope of the accompanying claims.

least in part to ultra-violet radiation, spaced f thermionically active electrodes of the indirectly heated type, the heater elements thereof being electricall connected in series, and

in electrical paral el relation to the ther'- mionically active elements of said cathodes, and substantially only mercury vapor at pressures ranging from .001 to .08 millimeters tof mercury.

2. An ultraviolet lamp of the gaseous-conduction negative-glow type com rising an enclosing envelope, a plurality ofp electrodes and a gaseous iilling, the major portion ot said envelope being substantially impervious to ultraviolet radiations and a restricted portion of said envelope being permeable to ultraviolet radiations the restricted portion of said envelope being small as compared to the area of said major portion, the composition of said restricted ortion of the said envelope being substantially the same as that of the major portion of the envelope, said restricted portion being homogeneously united to said major portion of the envelope.

3. An ultraviolet lamp of the gaseous-conduction negative-glow type com rising an enclosing envelope, a plurality o electrodes and a gaseous filling, a portion of said envelope being of greater thickness than another portion thereof and substantially impervious to ultraviolet radiations, said other portion thereof being suciently thin to be permeable to ultraviolet radiations the composition of said first mentioned portion being substantially the same as that of said other portion, said other portion being homogeneously united with said first mentioned portion. v d. An ultraviolet lamp of the gaseous-conduction negative-glow type com rising an enclosing envelope, a plurality oP electrodes and a gaseous fllling, said envelope being substantially homogeneous, a portion of said envelope being of a thickness sufiicient to prevent ultraviolet radiation from passing therethrough, and a bulbous portion homogeneousl united with said other portion, said bul ous portion having at least a portion thereof o suicient thinness to allow the passage of ultraviolet radiations therethrough, the composition of said first mentioned portion of said envelope and said bulbous portion being substantially the same.

'5. An ultraviolet lamp of the gaseous-conduction negative-glow type com rising an' enclosing envelope, a plurality o electrodes and a gaseous filling consisting substantially completely of a metal of relatively high y vapor ressure, said envelope having a portion t ereof substantially impervlous to ultraviolet radiations and another rtion thereof permeable to ultraviolet radiations, the area of said second mentioned portion being relatively small as compared to the area of said first mentioned portion, the composition of the second mentioned portion eing substantially the same as that of said rst mentioned portion, said second mentioned portion being h'omogeneously united with said rst mentioned portion.

6. An ultraviolet lamp of the gaseous conduction negative glow type comprising an enclosing envelope, a plurality of electrodes and a gaseous filling therein, said envelope comprising a major portion and a restriction portion, the area of said major portion being large as compared to the area of said restricted portion, said restricted portion bein in the form of a bulbous thin window W ose composition is substantially the same as that of said major portion, said restricted portion being homogenously united with said major portlon.

7. An ultraviolet lamp of the gaseous conduction type comprising an enclosing envelope, a plurality of spaced thermionically active cathodes of the indirectly heated type and a gaseous filling therein, the heater elements thereof being electrically connected in series and in electrical parallel relation to the thermionically active elements of said cathodes and substantially only mercury vanomus y' z.

por at s Ypressure ranging from 0.01 to 0.8 millimeters of mercury, said envelope having a major portion and a restricted portion, the area of said'major portion being large as compared to the area of said restricted portlon, the composition of said major portion being substantially the same as the compositori of said restricted portion, said restricted portion bein in the form of a bulbous window whose t ickness is relatively small as compared to the thickness of the major portion.

8. An ultraviolet lamp of the gaseous conduction negative glow type comprisingan enclosing envelope,a plurality of electrodes and a gaseous filling therein, said envelope comprlsing a major portion and a restricted portion, the area of said major portion being large as compaed to the area of said restricted portion, said restricted portion being in the form of a bulbous thin window Whose vcomposition is the same as that of said ma-

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