US2398111A - Discharge device - Google Patents

Description

April 1945- E. B. NOE-EL 2,398,111

DISCHARGE DEVICE Filed Feb. 19, 1945 lnven'kor:

Edward B. Noel, y

His A't'torney.

Patented Apr. 9, 1946 DISCHARGE DEVICE Edward 1:. Noel, Cleveland Heights, om, aslignor to General Electric Company, a corporation of New York Application February 19, 1943, Serial No. 478,377

6 Claims.

This invention relates to discharge devices and associated heaters and ballasts, and is especially adaptable and advantageous for erythemal ultraviolet metal-vapor lamps such as so-called sun lamps. For this purpose, the invention allows of doing away with costly accessories, such as ballasting transformers, and replacing them with inexpensive simple ballasts, even of pure resistance type; it allows of dispensing with the usual outer bulb or envelope used to filter the radiation from the discharge and to protect the discharge device proper from drafts or oxidizing influences; it allows of substituting cheaper glass (such as commonly used in the outer envelopes of "S4" sunlamps tor example) for the relatively expensive fused quartz or quartz glass" heretofore generally used for the discharge-envelopes or erythemal lamps; and it permits making the envelopes with an ordinary stem type of end construction, instead of with the usual quartz seals, and on ordinary automatic lamp machines rather than by hand. Other features and advantages of the invention will become apparent from the description of a species or form of embodiment, and from the drawings.

The drawing shows a cross-section through an erythexnai discharge lamp unit conveniently embodying the invention, part of the lamp base appearing in side elevation, and also shows suitable circuit connections for the unit. The discharge lamp L is here shown as of positive column type, with a short tubular envelope it that may contain metal such as mercury, for example, as the principal working substance, and usually also starting see such as argon, or other inert or rare gasies). The amount oi mercury (indicated by a glohule ii) is preferably so small that it is all, vaporized during the operation of the lamp L, thus limiting the operating pressure to a desired value, such as one to two atmospheres absolute pressure, for instance.

At one end, the lamp envelope it has a conventional reentrant stem-and-fiare construction i 2 with an inlead seal press it, and an exhaust tube it opening through the press and itself sealed off at it. Accordingly, there is an annular do space around the stem l2 inside the reduced neclr end it of the envelope it, as well as some dead space inside the tube is, which is not adequately heated by the discharge. nor by radiation, convection, or conduction from the electrode means at this end of the envelope. Current leads ll, it extend in through the seal it and carry the main coacting discharge electrodes 2t, 2!, which are here shown as located in opposite ends or therenvelope Ill, and of ell-heating type. They may consist of tungsten activated with alkaline earth oxide, such as a mixture including bariiun and strontium oxides, for instance. The lead I1 is shown as extending through the discharge space to the electrode 20 remote from the stem 12, and as having an insulatlve sheathing 22 from the stem I2 along past th discharge gap between the electrodes 20. 2|, this sheath being made, if desired. of heat-resistant glass like Pyre x," for example. To facilitate starting the discharge, a specially heated tungsten electrode coil 23 (which may be activated with oxide(s) such as used for the electrodes 2!], 2 I, though this is not necessary) is shown adjacent the electrode 2| at the stem end of the envelope It, being connected between the corresponding inlead l8 and an additional lead 24 extending out through the seal Ill. Outside the envelope It, the leads ll, I8, 25 may be connected to suitable contacts on a lamp base B, here shown as substantially coaxial with th lamp L, and as of screw type somewhat like that in Patent No. 2,160,431 to Buser, with contacts in the form 01 a screw shell 25, a center or end contact 26, and an intermediate annular contact 27 alsoexposed and engaging endwise.

Certain obviou peculiarities as regards the attachment of the base B to the lamp L will be explained hereinafter.

In accordance with the invention, an electric heater H which is also available as resistance for bailasting the lamp discharge is mounted around the'envelope Ill to heat the dead space surrounding the stem i2, being here shown as a resistance coil (of Nichrome wire, for example) wound in a helical groove of a refractory heat-difiusing hollow support ti. This support 3i may take the form of a flanged sleeve of heat-resistant electrical ihsulative material like lava or porcelain, and is shown as mounted adjacent the wall of a hollowed or concave reflector 32 associated with the lamp L and heater H, in alignment with a rear opening 33 in this reflector. Thus thepart of the lamp envelope it around the discharge gap between the electrodes 26, 2! is left freely exposed and unheated externally. The heat of the heater H not only heats up the dead space around the stem l2 and in the exhaust tube It sufficiently to prevent condensation of mercury in these spaces, which are not heated adequately from the discharge in the lamp L, but may also supplement the heat fromthe lamp in warming the person or the body area exposed to the erythemal ultraviolet radiation from the lamp, affording a beneficial infrared treatmentas well as a comfortable sense of warmth. Of these effects, the heating up oi the dead space in the envelope It to obviate or revaporize mercury condensation is generally the more important, since it assures the intended pressure oi mercury vapor in the envelope on which depends an adequate output oi ultraviolet radiation oi the desired wavelength.

While it is desired to maintain the stem end oi the lamp envelope ID at a sumcient temperature (approximating that oi the rest of the envelope) by means-of the heater K. it may be objectionable to subject the lamp base B and the coacting socket structure 8 to such high temperatures; and to avoid this, provision is made to separate the base 13 proper irom the stem end or neck It oi the envelope III. For this purpose, the base 13 is provided with an extension oi its shell in the form of a long skirt 3! rather larger than the shell 25. This skirt I5 may consist of a cylindrical glass sleeve having one end reduced at ll to a neck that enters the base shell 2! and is secured therein by means of basing cement (not shown), and having its other end open to receive the usual reduced neck end It of the lamp envelope or bulb Ill. The bulb neck I! may be secured in the skirt by fusion to the latter as indicated at 31, or with suitable heat-resistant and heat-transmitting cement 38 (such as a high-temperature basing cement) iilling the space between the neck It and the skirt, or both. Even disregarding the location of the heater H directly around the envelope neck It, the skirt 3! is in heating relation to the envelope portion I8 and the heater H to the skirt 3!. As shown, the base skirt It is so long as to extend out through the reflector opening 33, so that the base B proper and the socket B are altogether outside the zone of concentrated heat inside the reflector 32. In the present instance, the heater H is secured to the reflector 32 by screw bolts 39 taking through the flange oi the heater support II and through the marginal flange of the reflector 32 around its opening 33. The socket S is shown connected to the heater support 3i (as well as to the reflector 32) by supporting means in the skeleton form of Z-bar clips 40 whose upper, forward end-feet take the bolts 88, and whose lower, rear end-feet take screws 4i which take through a metal base 42 associated with a porcelain shell 43 of the socket 8, thus securing said base 42 andshell 43 together. In practice, oi course, the socket S and associated parts at the rear of the reflector 32 may be enclosed in a suitable hollow sheet metal or other canopy, indicated at 44.

As diagrammatically indicated in the drawin one end oi the heater coil is connected directly to one side oi the main power supply circuit P, which may be either A. C. or D. C., whfle the other end oi this coil 30 is connected by a circuit lead 45 to the socket contact 48 that coacts with the lamp base center contact 26 for the main lamp electrode ii. The socket contacts 41, 48 that coact with the base contacts 25 and 11 for the main and auxiliary electrodes Ii. 28 are connected by circuit leads 60, I to a three-way switch as by means oi which either lead 5|, 5| may be electrically connected to the other side of the main power supply circuit P. Initially. in starting the lamp, the electrode 28 may be connected in circuit with the electrode II until it heats sufllciently to aflord an ample supply oi electrons for the discharge, and then the discharge may be thrown over to the electrode ll by disconnecting the lead 5| irom the circuit P at the switch x and connecting the lead II to said circuit P. In practice, oi course, the switch 2: may be an automatic thermal switch oi any suitable iour-terminal type that will aiiord proper heating time ior the electrode 2| before acting as described Besides the advantage of heating the stem end oi the lamp envelope l0 adequately and thus allowing the envelope to be made oi simple, inexpensive design and construction, and on ordinary automatic stem making and sealing-in machinery, my invention afl'ords the advantage that the heater resistance as can readily be made oi ample size to ballast the discharge properly and furnish all necessar heat without having to operate at a temperature which might abridge its length of service, and that the heater H is not structurally part of the lamp L, and hence does not become a loss when the lamp iails prematurely or otherwise, but may outlast a number oi lamps. Furthermore, the stem end oi the lamp envelope In is effectively heated without materially heating the base B, as would tend to be the-case if the heater H were included in the lamp structure, whether within the stem i2, or in the base shell 25, or in a skirt extension of this shell corresponding to that at 35: on the contrary, the base B and the socket 8 may readily be located out of the zone of heat due to the lamp L and the heater H, as iar and as effectively as desired. Equally, the main portion of the lamp envelope III around the discharge gap is left unobscured, unobstructed, and externally unheated, so that there i no danger oi overheating and rupturing it locally anywhere, and no loss of the radiation from the discharge.

What I claim as new and desire to secure by Letters Patent of the United States is:

i. The combination with a high pressure discharge lamp having a reentrant stem and inlead seal at one end of its discharge envelope, of an electric heater surrounding the dead space of the lamp envelope around said stem for externally heating this dead space, though leaving xposed and externally unheated the envelope portion around the discharge gap of the lamp, and connected in series with the lamp for ballasting the lamp discharge.

2. The combination with a high pressure discharge lamp having a reentrant stem and inlead seal at one end oi its discharge envelope, and also provided with a base for this end of said envelope, of an electric heater surrounding the dead space oi the lamp envelope around said stem, to the exclusion both of said base and of the envelope portion around the discharge gap of the lamp.

3. The combination with a high pressure discharge lamp having a reentrant stem and inlead seal at one end of its discharge envelope, and also provided with a base having an extended skirt attached to this end of said envelope and in heating relation thereto, oi an electric heater surrounding the base skirt, to the exclusion both of the base proper and of the envelope portion around the discharge gap of the lamp, for externally heating said skirt and the dead space of the lamp envelope around said stem.

4. The combination with an apertured hollow reflector and an associated lamp socket mounted externally of said reflector at its opening, oi a high pressure discharge lamp in said reflector having a base in said socket and also having a reentrant stem and inlead seal at the based end of its envelope, inside the reflector, and an electric heater in said reflector surrounding the dead space of the lamp envelope around said stem for externally heating this dead space, through leaving exposed and externall unheated the envelope portion around the discharge gap of the lamp.

5. The combination with an apertured reflector and an associated lamp socket mounted externally of said reflector at its opening, of a high pressure discharge lamp having a long-skirted base in said socket, and having a reentrant stem and inlead seal at its based end, inside the reflector, and an electric heater mounted in said reflector around said base skirt for externally heating said skirt and the dead space of the lamp envelope around its said stem, though leaving exposed and externall unheated the envelope portion around the discharge gap of the lamp,

and connected through one of the lamp socket contacts in series with the lamp for ballasting the lamp discharge.

6. The combination with a rear-apertured hollow reflector and an associated lamp socket to v leaving exposed and externally unheated the em velope portion around the discharge gap of the lamp.

EDWARD B. NOEL.

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