US2284775A - Ultra violet light source - Google Patents

Description

June 2,1942 G. sPER-rl ULTRA VIOLET LIGHT SOURCE Filed Aug. 3, 1940 INVENTOK GEORGE SPE-Rn. @llaa v ATTORNEYS.

Patented June 2, 1942 ULTRA VIOLET LIGHT soUncE George Sperti, Covington, Ky., assigner to Science Laboratories, Inc., Norwood, Ohio, a corporation of Ohio Application August 3, 1940, Serial No. 350,425

9 Claims.

Figure 1 is a longitudinal sectional view of the' light source showing the assembly of parts exelusive of the base.

Fig. 2 is an end elevational view of one of the electrode structures.

Fig. 3 is a sectional view of the electrode structure taken along the lines 3 3 of Fig. 2.

Fig. 4 is av Wiring or .circuit diagram illustrative oi the operation of the light source.

The light sources to which my invention is particularly addressed are light sources combining an arc discharge in an ionizable atmosphere, preferably though not necessarily containing mercury, with means for giving radiation in the visible spectrum. Lamps of this type though they have utility for periodic therapy, activation or sterilization treatments are nevertheless of high value for use as or in connection with sources of visual light; and the envelope may be so chosen in connection with the intensity of the ultra violet radi-ation produced by the light sources as to eliminate not only the irritant effect of the shorter ultra violet Wave lengths but also any tendency to harm the unshielded eye. Consequently the light sourceslare of utility for continuous use in school rooms and the like and further as set forth in my copending application entitled Sources of visual and ultra. violet radiation, Serial No. 350,424, filed August 3, 1940, are useful for color work and the like. f

Referring to the drawing, I have indicated at I an envelopeperviousto ultra violet radiation but preferably having a filtering effect thereon. The envelope may be of quartz or any of the glasses pervious to ultra, violet light, such for example as Corex. `The envelope is provided with a press 2 through which pass and into which are fused the power leads I and 5. 'I'he press has a scalable tube 6* as a part of it, through which tube the atmosphere and degree of evacuation of the envelope are controlled in the manufacture of the light source.

- The power lead 5 within the envelope bears an electrode assembly indicated generally in Fig. 1 at E. An insulative tube 6 which may be of ordinary glass or of the same material as the envelope is fused to the press so as to be rigid therewith and carries internally the lead I. The tube 0 extends nearly to the opposite end of the envelope and at that end the lead 4 or a member fused to it bears the second electrode assembly E which is indirectly supported thereby. The filament F which will be described more in detail hereinafter passes between the electrode structures and is attached to the respective power leads. The lila-ment throughout its length at suitable intervals is supported by engagement means 9 having an attachment I0 to the tube 6. My light source may be made more resistant to shocks by supporting the outer end of tube B. I have shown this accomplished by a Wire member l, which may be bent in a serpentine fashion to give it greater resiliency, and the end of which may engage the envelope as at 8.

The atmosphere in the envelope will be of suitable composition and pressure to start an arc discharge and the envelope will also contain preferably a small quantity of mercury adapted to be vaporlzed during the operation of the light source. In order to make the device self starting I provide in connection with each electrode structure a means which, when heated bythe illament, is adapted to give off ions and to ionize the adjacent gas.

Moreover since I do not desire to have the arc continuously operative between portions of the filament I provide separate arc electrodes. These I conveniently make in the form of an open coil of conductive wire II as most clearly shown in Figs. 2 and 3. The coil has fused to it at one side a bar I2 to tie the convolutions together and to support the coil, and this bar in turn is fused to the power lead 5. It will be understood that the electrode structure at each end of the light source may be the same, and has been so shown. However, for sources designed to operate only on direct current, I may employ one electrode of the form shown and described herein, and a second electrode not requiring ionizing means. The said second electrode may thus be a suitably shaped piece of any refractory metal.

Within the hollow of the coil II I provide a longitudinallyperforated lnsulative block I3; and the lament F is threaded in and out of the perforations in the block so that the activation of the filament will heat the block. The block bears a cylindrical metallic sheath I4 4coated as at I5 with a refractory `oxide or other suitable substance adapted to give oi! electrons when heated. The assembly of the block, sheath, and coating lies inside the coil il and may be tacked to it by fusion to prevent displacement.

The filament F is a heavy lament, and as indicated, it connects the two power leads so as to close the circuit between them. The light source will have a suitable base (not shown) which is conveniently of the screw-base type but may also be of the bayonet type, if desired. It is in either event a two-contact base; and the lamp in its operation requires no external starting means but only an impedance for balancing the arc. The impedance may be a choke, a transformer, a resistance, or a light source capable of delivery light in the visual spectrum.

When power is applied to the device the iilament F, completing the circuit between the power leads is made to glow. 'I'he portions of the filament passing through the insulative blocks I3 heat these blocks and cause the emissive coating on their sheaths to ionize the adjacent atmosphere within the envelope. The open-work character of the electrode structures I i facilitates this ionization. When the ionization adjacent the electrode structures has progressed far enough, an arc begins to form between the electrode structures il and adjacent portions of the filament F, which, by reason of the resistance of the filament, are at potentials differing from the potentials of the electrode structures. The initial arc or arcs thus formed, however, rapidly travel along the iilament until they meet, and until the main arc discharge occurs directly between the electrode structures Il. The construction of my light source is such that as soon as the main arc is formed the filament no longer acts as an electrode and is therefore protected from the arc.

My light scurce is fully self starting and self re-starting. It can be made in convenient sizes and with normal screw bases. Where desired, the balancing impedance may be enclosed within the base so that no external impedance is required.

Modiileations may be made in my invention wtihout departing from the spirit of it.

Having described an exemplary embodiment of my invention I have in the appended claims `set forth the invention which I believe is inherent in my disclosure.

I claim:

1. In a light source, an envelope, a press at one part of said envelope, a pair of leads passing through said press, one of said leads terminating adjacent said press within said envelope, a nonconductive tubular support sealed to said press, the other of said power leads passing. both through said press and through said tubular support to a point remote from said press, each of said power leads bearing electrode structures, resilient means on said power lead at the free end of said tubular support, said resilient means engaging said envelope, and a filament connected between said power leads.

2. In a light source, an envelope, a press at one part of said envelope, a pair oi' leads passing through said press. one of said leads terminating adjacent said press within said envelope, a nonconductive tubular support rigidly fastened to said press, the other of said power leads passing both through said press and through said tubular support to a point remote from said press, each of said power leads bearing electrode structures, resilient means on said power lead at the free end of said tubular support, said resilient means engaging said envelope, said resilient means comprising a metal member reversely bent to provide increased resilience, and having a free end engaging said envelope, and a filament connected between said power leads.

3. In a light source, an envelope, a press at one part of said envelope, a pair of leads passing through said press, one of said leads terminating adjacent said press within said envelope, a nonconductive tubular support fastened to said press the other of said power leads passing both through said press and through said tubular support to a point remote from said press, each of said power leads bearing electrode structures, and a lament within said envelope external to said support, attached to said power leads and substantially paralleling said tubular support.

4. In a light source, an envelope, a press at one part of said envelope, a pair of leads passing through said press, one of said leads terminating adjacent said press within said envelope, a nonconductive tubular support fastened to said press, the other of said power leads passing both through said press and through said tubular support to a point remote from said press each bf said power leads bearing electrode structures, a filament within said envelope attached to said power leads and substantially paralleling said tubular support, and supporting means for said lament comprising means engaging said filament and attached to said tubular support.

5. In a light source, an envelope, a press at one part of said envelope, a pair of leads passing through said press, one of said leads ter- `minating adjacent said press within said envelope, a non-conductive tubular support fastened to said press, the other of said power leads passing both through said press and through said tubular support to a point remote from said press, each of said power leads bearing electrode structures, and a filament within said envelope attached to said power leads and substantially paralleling said tubular support, at least one of said electrodes comprising a hollow gridlike member, a sheath within said member and bearing an electron emissive coating, said iilament passing within and being supported within said sheath so as to heat said sheath.

6. In a light source, an elongated envelope, a press adjacent one end of said envelope, a pair of leads passing through said press, one of said leads terminating adjacent said press within said envelope, a non-conductive tubular support fastened to said press, the other of said power leads passing both through said press and through said tubular support to a point adjacent the other end of said envelope, each of said power leads bearing electrode structures, and a filament within said envelope attached to said power leads and substantially paralleling said tubular support, each of said electrodes comprising a hollow grid-like member, a sheath within said member and bearing an electron emissive coating, said lament passing within and being supported within said sheath so as to heat said sheath, said sheath containing a perforated insulative block, said filament passing through the perforations in said block.

'1. In a light source, an elongated envelope, a press adjacent one end of said envelope, a pair of leads passing through said press, one of said leads terminating adjacent said press within said envelope, a non-conductive tubular support fastened to said press, the other of said power leads passing both through said press and through said tubular support to a point adjacent the other end of said, envelope, each of said Apower leads bearing electrode structures, anda sheath, and supporting means for said lamentl comprising means engaging said lament and attached to said supporting tube.

8. In a light source, an envelope, a press at one part of said envelope, a pair of leads passing through said press, one of said leads terminating adjacent said press within said envelope, a non-conductive tubular support fastened to said press, the other of said power leads passing both through said press and through said tubular support to a point remote from said press, each of said power leads bearing electrode structures, and a filament within said envelope attached to'said power leads and substantially paralleling said tubular support, at least one of said electrodes comprising a hollow grid-like member, a sheath within said member and bearing an electron emissive coating, said iilament passing within and being supported within said sheath so as to heat said sheath, said sheath vcontaining a perforated insulative block, said lament passing through the perforations in said block, and supporting means for said iliament comprising means engaging said filament and attached to said supporting tube.

9. In a light source of the character described, an envelope, a press at one part of said envelope, a tubular vitreous support fused to said press, a pair of power leads passing through said press, one of said leads terminating adjacent said press and near one end of said envelope, the other of said leads passing through said press and said tubular support and terminating at a point remote from said press, means for supporting the free end of said tubular support with reference to said envelope, electrode structures at the ends of each lead, at least one of said electrode structures comprising a grid, means inside said grid coated with anelectron emissive substance, and a filament substantially paralleling said tubular support and having its ends respectively attached to said leads, said lament intermediate its length passing into said means coated with an electron emissive substance so as to heat said means.

GEORGE SPERTI.

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