US 2135714 A
Description (OCR text may contain errors)
Nov. 8, 1938. G. E. INMAN 2,135,714
`ELECTRIC LAMP Filed Aug. 10, 1934 3 Sheets-Sheet l Inventor: George Elnm r1, y @lis-'At torney.
GA E. INMAN 2,135,714
Nov. 8, 1938.
ELECTRIC LAMP Filed Aug. 10, 1934 5 Sheets-Sheet 2 Inventor: George Inman H i) by Hwttohey.
G. E. :NMAN 2,135,714
ELECTRIC LAMP Filed Aug. 1o, 1%1 5 sheetssheet 5 FTQ. H.
Inventor: George E. Inman,
Patented Nov.. 8, 1938 ELECTRIC LAMP George E. Inman,
New York East Cleveland, Ohio, assigner to General Electric Company,
a corporation of Application August 1c, 1934, serian N. 739,271'
15 claims. (ci. 17o- 1) This invention relates to electric lamps and the like, and especially to glow discharge vapor lamps such as the so-called low pressure positive column type or the cathodic glow type, giving diffuse rather than sharply localized or intense concentrated luminosity. The invention is concerned with lamps that contain a vaporizable vworking substance,e. g., sodium and some other metals-and operate with very small vapor prassures of such substance. In such lamps, the absolute vapor pressure of the working substance is usually about 1 or 2 microns for sodium. Vapor pressures of low order are characteristic of the typical diffuse glow discharge, that generally appear toflll the whole lamp bulb. Very usually, such lamps contain a small amount of easily ionized gas, like neon, argon, etc., whose (partial) pressure in the lamp is around 1 or 2 to 7mm., to assist in starting the sodium or other vapor discharge. lThis is the more desirable in lamps using a difiicultly vaporizable working substance like sodiumas contrasted with one that is more easily vaporized like mercury. Commercial sodium vapor lamps aim at operating temperatures around 250v C. for maximum efficiency; while the actual temperatures of their envelope or bulb walls range from about 220 C.
vis made to remedy this by v heated by its glow discharge;
or less to about 275 C. or more. The boiling point of sodiumbeing about 877 C., the sodium vapor in the commercial lamp bulb is continually condensing on itsinner surface and vaporizing again, with a tendency to accumulate and remain in any region or area that is relatively cool, because of the l,slower vaporization from the cooler region. This means thatvthe sodium vapor pressure in the envelope will tend to fall below that corresponding to the general lamp temperature, and to approach that correspondingto the lowest temperature: i. e., thatthe lamp will virtually lack sodium, and its light outputY and cihciency'suier correspondingly. Or if the attempt forcing the lamp to operate at a higher current density in the glow discharge, and thus heat up its coolest region(s) to 250 C. or thereabout, then the general lamp temperature will be forced still higher, and the eiciency will also suier.
' Practically, it is very dimcult to designa commercial lamp of the glow discharge type containso as to be evenly and the variation in wall temperature is apt to be even less favoring diiculty vaporizing metal 4able than the above-suggested range of I220" C. to
275 C. in the sodium vapor lamp.
While an adequate though small vapor pressure of sodium or the like is essential to the operation of a glow discharge vapor lamp, and while the most favorable sodium pressure for efliciency is that corresponding to a (uniform) temperature of about 250 C., the current density in the glow 6 discharge is also very important to the ecency,
and in a contrary sense: i. re.,'the lower the current density, the greater the luminous efliciency of the glow discharge. However, glow discharge currents that would be highly favorable from this 10 point of view are insufiicient to heat the lamp to the temperature that is most favorable as regards vapor pressure of a working substance such as sodium. This is so even when the sodium vapor lamp is operated in a double-walled vacuum jack. 15 et in order to conserve heat, as is customary.
Other limitations and drawbacks of such vapor lamps have lain in the necessity of a ballast re sistance in series with the lamp, to control and limit rise of current through the lamp as it heats up; and of either providing compensating resistances, reactors, or transformers to allow such lamps to operate in parallel on ordinary (alternating current) lighting circuits of `1l0- 120 volts-or else operating a. lurality of the lamps in series.
I have found that these difficulties can be overcome, and a very high operating efficiency realized in a lamp of this general type, by supplying additional heat, as uniformly as possible or as nearly according to the deficiency inthe various parts of the lamp as possible, so as to maintain a proper uniform lamp temperature with a relatively low glow discharge current, or current density. Preferably, and ashereinafter described, 35 the lamp is heated externally. Suitable electrical heating means for this purpose may be operated independently, from a separate heating circuit, or may be adapted and used to ballast the lamp, or may be used to compensate for its low operating voltage. Useful light may be obtained from an incandescent b'ody aswell as heat; and the enhanced luminous eiciency of the glow discharge wills-largely, at least, make up for the relatively poor luminous eiileciency of such afilament.
I also aim to provide a simple, compact, convenient lamp unit.- needing no extrinsic acces-v series such as external ballast, compensating resistance,` reactor, ortransformer, and not even requiring the usual enclosing vacuum jacket; and to secure relativelyhigh over-all eilciency of the whole unit. In a lamp unit of this character, I arrange for externally heating the'glow discharge A lamp envelope or bulb walls as uniformly as possible all over, partly by arranging a plurality of ably arranged to throw their heat on the un-4 blankete'd or outward-facing walls of the closely grouped glow discharge lamp means. A particularly favorable combination is to alternate lamps or tubes and heating means in a more or less regular, symmetrical arrangement with respect to a common axis. I have here particularly illusandiilaments II, II arranged in alternation, at`
trated and described my invention as applied to one or more glow discharge lamps of cylindrical -.or tubular form enclosed with the external heating means in a cylindrical or tubular evacuated outer envelope; but while the cylindrical or tubular shape lends itself very advantageously to my purpose, it is not essential. and the invention in its broader aspects can -be adapted to other shapes of glow discharge lamp and outer envelope. i
I aim, furthermore, to provide light of improved quality by combining different light color tones (produced either in the. same glow' discharge lamp, or in separate glow discharge lamps) with two or more different ones of such working substances as sodium; potassium: or other alkali metal, mercury, cadmium, calcium. or magnesium,'etc.; also by combining the light of solid filaments or glow bodieswith glow discharge vapor lamp light. I Either or both of these measures may be employed in lighting units such as referred to in thepreceding paragraph. A
Various other features and advantages of the invention will appear from the following description of species thereof, and from the drawings.
In the drawings, Fig. l is a side view of one form of lamp unit embodying my invention; Fig. 2 is a view of the mount of the unit shown in Fig. l at right angles to Fig. 1, without the outer .enclosing envelope or the contact terminals of Fig. 1; Fig. 3 is a somewhat diagrammatic plan view of the mount; Fig. 4 is a view similar to Fig. 1 illustrating a lainp unit of somewhat different construction, with an electrode of one of its glow discharge lamps in axial vertical sec-- vention; Fig. 10 is a schematic wiring diagram.
of the embodiment of the invention illustrated in Figs. 1 to 3 and the embodiment of the invention illustrated in Figs. 4 to 6 and Fig. 11 is a' schematic wiring diagram ofthe embodiment of the'invention illustrated in Figs. 'I and 8 and the embodiment of the invention illustrated inFlg. 9.
4 The device shown in Figs. 1-3 comprises elongated, tubularv glow discharge vapor lamps I0, I
substantially uniform intervals, and in symmetry with respect .to a common axis or center. This gives a substantially uniform distribution of light and heat. As only two lamp tubes I0, I 0 and two filaments II, II are usedvin this particuiar' device, the arrangement is a quadrated gaps) and iilaments II, II extend in the same general direction, substantially or approximately paral1el.- Lamps I0 and filaments II are all enclosed in an evacuated and sealed (glass) envelope or bulb I2, of tubular form, which not only protects the filaments Afrom the atmospheric oxygen, but also minimizes radiation and loss of heat from the lamps, as well as from the iilaments. rlfhe laments II, II are preferably of tungsten,
vor other material having a positive temperatureresistance coeilicient.
In the present instance, the device is shown equipped with a` unitary base and contact terminal structure I3 which in effect forms part of the outer envelope I2 itself, rather than with a separate base secured to an envelope complete in itself, apart from the basel This structuren comprises a cup-like body I 4 of glass with downward projecting hollow nipples I5, I5 to which are fused hollow metal terminal posts or thimblesleeves IG, I6 closed at their lower ends. Such a unitary contact terminal structure is commonly known in the artas a bi-post base. Metal current leads I1,4 I1, preferably of channel section, are attached to the hollow contact terminals I8, IB inside the latter, and extend up through the nipples I5, I5 into the cup-like body Il. 'I'here these leads I1, I1 are offset (by double bends) toward the center of.` the envelope I2, so as to extend 4inward close beside-one another substantially or approximately along the center or axis of the envelope and of the assemblage of lamps III, III and filaments II, II.v In other words, the lamps and filaments are arranged in a hollow coniiguration around the current leads I1, I1. The exhaust tip I 8' on the glass body I4 is also shown sealed oiI. t A
The lamps' III, I 0 are supported at their lower ends by or from the structure I8, and at their upper ends by or from the upper or inner ends of the leads'I1, I1. As here shown, each lamp II) comprises as its envelope a glass tube with annularly shouldered or ridged metal contact .discs I8, I8, fused to its ends. In the particular construction lhere illustrated, the lower ends of the lamps Ill, III rest against an insulating bar or block 20 that extends diametrallyacross the interior of the cup-like body Il, this block 20 being notched at 2|, 2| to receive the ridge of each lower disc. I8 and aiord a button" to engage inside this annular ridge. The upper end of each lamp II) vis held by a flexible wire spring nnger 22 that has one end fastened to the upper end of one of the leads I1, and has la circular loop 23 on its free end to engage around the annular ridge of the corresponding disc I8. Each spring finger 22 electrically connects its lead I1 to ,the upper contact I8 of its lamp I Il, and presses the ridge of the lower contact I8 against a sheet metal contact strip 2l that extends .into one of prises two separate wire sections which carryglass insulating beads 28, 21 and have their adjacent ends fused into a glass insulating and connecting bead 28. Lower and upper support arms 30, 3I are welded to the corresponding insulatively separatedupper and lower sections of the upright 25 and to the ends ofthe filament II, and serve as current connections for the filament Il. Intermediate support arms 32, 32 are fused into the glass beads 26, 21, 28 to serve as anchors. Each upright 25 is insulatively supported from the corresponding main current lead I1 by composite insulating arms 33, 33, whose wire sections are fused into glass insulating beads.
' To ballast the lamps I8, I8, each of them is connected in series with one of the filaments II, II. While the resultant lamp-and-filament sets may be cnnected'in parallel between the leads I1, I1, in the present instance I have shown them,
in series with one another between said leads, so that the device can be operated on standard lighting circuits of around 110 to 120 volts without being excessively large, or requiring excessively fine filaments II, II. For this purpose,
the upper sections of the uprights 25, 25 arev interconnected by a wire 35 extending across the upper end of the bulb I2, above or between the ngers 22, 22-indeed, this Wire 35 and the sections of the uprights 25, 25 which itconnects may consist of one single length of wire bent to an inverted U shape, as here shownand the lower ends of the lower sections of the uprights 25, 25 are connected by wires 36, 36 to the contact strips 24, 24. Thus the filaments II, II are connected in series between the lower ends of the lamps I8, I8, whose upper ends are connected to the leads I1, I1 as already described.
Recurring to Fig. 1, and referring to the internal features or mounts of the lamps I8, I8, it will be seen that each lamp`has in the opposite ends of its tubular envelope the electrodes 48, 48, preferably of indirectly heated type such as known in the art. These electrodes 48, 48 are supported by an upright 4I comprising a main wire section and lower and upper Wire L parts 42,43 attached to .said main section by insulating glass beads 44, 44 into which the parts are fused. From the main wire section project wire arms 45, 45 Welded thereto, parallel with the arms of the parts 42, 43 and spaced from them about the length of the electrodes 48, 48. One electrode 48-or, more properly speaking, itsvinternal heating resistance 46-is connected between the lower arms .42 and 45, and the other between the upper arms 43 and 45. An insulating refractory sleeve 41 (or a glass tube) surrounds the main section of upright 4I between the arms 45, 45. The lower arm 42 has welded thereto a wire support 48 that engages the' lower disc I8 and electrically connects the arm thereto, and the upper arm 43 has a flexible electrical connection 49 to the upper disc I8. Thus the internal heating resstances 46, 46 of the electrodes 48, 48 are electrically connected in series between the lower and upper discs I8, I8.
To the insulating sleeve or tube 41 of each glow discharge lamp I8 is attached a hermetic capsule 58 containing a charge of sodium or other such vaporizable Working substance for the lamp. This capsule 58 may be of glass hermetically sealed, and may be encased in a piece of thinwalled nickel tubing 5I crimped in at the ends to retain the capsule. The capsule 58 is thus installed on the mount of the lamp lo before, the vmount is sealed into its tubular envelope. After the vlamp-I8 has been exhausted-and preferably quency coil is powerful enough, the metal casing 5I may be dispensed with;-although it is useful to retain the pieces of the ruptured capsule. If preferred, the rupturing of the capsule 58 may be done after the lamps I8, I8 have been installed in the outer envelope I2, and the latter exhausted and sealed off.
Besides the charge of sodium or the like, each lamp I8 preferably contains a tenuous atmosphere of neon, argon, or other suitable gas that is readily ionized. This is introduced after the lamp I8 is exhausted,'but before it is sealed oi.
In the operation of the device, starting cold, the currentiiows at rst through the electrodeheating resistances 46, 46 and the main section of the upright 4I of each lamp I8, in series; but as the electrodes 48, 48 heat up, more and more current is carried by ions of the neon or other gas in the gap between them. As the whole lamp `I8 heats up and vaporizes some sodium or other metal, the metal ions participate in the luminous discharge, in shunt with the resistances46, 46 and upright 4I. Besides being internally heated by its electrode-heaters 46, 46, and, its glow discharge, each lamp I8 is externally heated by the adjacent lamp and by the laments II, I I, whose 4arrangement with reference to the lamps I8, I8 and the envelope I2 assures a very uniform distribution of this external heatto the lamp'tube walls; since the heat of the filaments striking the walls of the outer envelope I2 obliquely is reflected and reradiated back on `those portions of the lamp tube walls that receive theA least -heat directly. Thus the distribution of heat throughout the evacuated outer envelope I2 is very uniform.
. The vacuum in the envelope I2 minimizes loss of heat by conduction or convection. The efhcient external heating of the lamps I8, I8 by the filaments I I, II helps to .vaporize the sodium or other glow discharge eiciency than if the lamp itself had to be forced in order to vaporize more sodium by the heat of the glow`discharge;and thus the filaments II, II, though themselves generallynferior in luminous emciency to the lamps I8, I8, nevertheless very greatly increase the overall efclency of the whole device. Such a lamp may be operated at aboutu250 C. with a lglow discharge energy consumption as low as about 0.1 watt per square centimeter of envelope surface. The filaments II, II ballast the lamp I 8., I8 very satisfactorily, as already explained.
'I'he combination of'the light II of tungsten with the lyellow light from sodium pf filaments A'I I, v65
vapor gives a combined light o f improved quality. By using one lamp I8 with sodium and anafter it has been sealed off-the metal-cased cap- \'\yellow sodium and the blue-green mercury lighttones with the (yellowish) white of tungsten.
suie 58 is brought into the fleldof a high frequency coil externally surrounding the lamp I8.
Alsotwo or more working substances may be two lamps I and more than two tungsten or other filaments II can be used in an arrangement similar to that of Figs. 1 3; with different substances in the respective lamps, such as sodium, mercury, and cadmium.y More vcomplete mixture of the diierent kinds or color-tones of light can be obtained by enclosing the device in a light-diffusing globe, or by frosting the envelope I2, or by a combination of such measures.
In Figs. 4-6, the arrangement of the tubular lamps Illa, Illa and laments I I, I I is similar to that shown in Figs. 1-3, but the mounting is different, as well asl the construction of the lamps. In this instance, lamps Illa, Illa and laments I I, II are all supported entirely from the main terminal post leads I1, I 1. 'I'he iilaments II, I I are not coextensive with thelamps I0a, Illa throughout their full lengths, as in Figs. l and 2, but only with the'gaps between their electrodes 40a, 40a, or nearly so. Each lamp Illa has an all-glass 'envelope with current leads 53, 53 centrally sealed through its opposite ends andconnected to the axially arranged glow-discharge electrodes 40a,
40a, which-or their internal heating resistances 46a, 46a-are interconnected' by an axially ex-` tending (molybdenum) lead 4Ia, the upright 25 and associated parts of Figs. 1-3 being dispensed with. These electrodes 40a, 46a, are of internally emissive hollow type: i. e., each of them has -its electron-emissive material (such Kas barium oxide) on the inner surface of a (nickel) metal tube that is open toward the other electrode.
The lamps Illa, Illa are supported at their upper ends by or from the inner ends of the leads I1, I1, which extend side by side very much as in Figs. 1-3, but in the plane of the terminal posts I6, I6 instead of in a plane at right angles thereto. The leads I1, I1 are insulatively interconnected and spaced apartby braces 54, 54 welded tothe leads near `their lower and upper ends, each brace comprising wire-sections fused v into an insulative (glass) piece. Each lamp has its upper lead 53 attached and electrically connected to the horizontal arm of an (inverted) L-bent wirev lead support 55 whose upright member is fastened to the end of its (channel) lead I1. An insulative (L-bent) brace 56 comprising wire sections fused into a (glass) insulating piece has one end welded to the outer end of a lead 53 and its other end fastened to the en'd of a (channel) lead` I1. At the lower ends of the lamps I0a, IIIa, there are two U or J-bent lead wires 51, 51, whose short limbs are welded -to the lower lamp leads 53, 53, and whose long limbs extend upward in the plane of the laments I I, II, at right angles to that of the-lamp tube axes, and mid? way between them. For the short limb of each J 51, there are insulative braces 58, 58 (similar to the braces 54 and 56 in construction), extending from a common point on the J-limb to the two nleads I1, I1. The lower end of each filament II is (electrically) connected to the upstanding long limb of a J 51, and its upper end is connected to the depending limb of an (inverted) U-bent lead wire 35 that extends horizontally across between the upper ends of the lamps I0a, I0a. The horizontal' member 'of the U-bent lead wire 35 is shown in Fig. 5 as oiset to one side of the plane of the filaments Il, II, to keep it clear of the leads I1, I1. The upstandinglong limb of each lament II may have an insulative anchor support'GI, (similar to the braces 54, 56, 58, 60 in construction) welded to the adjacent lead I1 and embracing the filament about at mid-length.
Thus, it will be seen, the iilaments II, II are connected in series with one another by the wire 35, and the serially connected pair of them is connected in series between the lamps I Ila, IUa by the wires 51, 51. And the serial chain of lamp I0a,laments II, II, and lamp I 0a is connected in series. between the terminal leads l1, I1 by the lamp leads 53, 53.
In the device shown in Figs. 'l and 8, the two lamp tubes Ib, Illb corresponding to the separate lamps I II, Ill of Figs. 1-3 and 4-6 are limbs of a single (inverted) U-tube lamp, but are still arranged symmetrically and in alternation with the iilaments II, II, as in Figs. 1-6. The U-Iamp limbs I0b, IIlb are supported entirely from the base and terminal structure I 3, by means of separate saddle devices 20a, 20a, each consisting of a. glass flare fused to the upper end of a metal to lie against the inner wall of the U-bend of the lamp I 0b. The (g1ass).ends of the lamp IIIb may be fused to the (glass) flares of the saddle devices 20a, 2Ilaj The ilaments I I, II are only coextensive with the U-bent electrode gap, or approximately so. They are supported and Iinterconnected at their upper ends by a (nickel) lead wire 25h coiled around the bend of the U-lamp IUb about 11/2 turns, with its end portions at opposite sides of the exhaust tip 14 on of the saddle sleeves 10, 10, and extend upward beside one another neari-the axis of the envelope, etc'., like the leads 24, 24 in Figs. 1-3 and 4 6. 'Ihe support 24a forms a current lead connecting -its filament- IIl directly to the left-hand saddle sleeve 10 and terminal I6. The other support 24h, attached to the right-hand saddle sleeve 1P, comprises two sections mechanically connected but insulated from one another by a (glass) insulating piece 15, thus insulating the main section of this support from said sleeve 10. 'Ihe left-hand electrode lead 13 extends down through the corresponding sleeve 10, out through a hble in the sleeve wall in which itis insulatively sealed at 1 1, and then to the main section of the lead 24h, to which it is welded at 18. The righthand electrode-lead 13 extends down in the corresponding sleeve 10 and is welded thereto at 15. Thus the filaments lI I, I I are connected in series with one another and with the electrode gap 4I), 40 of the U-.lamp. e
In manufacture. `the U-lamp Illb with its internal parts is completed and exhausted, charged with neon or other gas and sodium or other working substance, and sealed oif at 15. Thenthe saddle devices 20a, 20a., are attached and the lead coil 25h put in place. 'I'he filaments II, III are installed and the. electrode leads 13, 13 are arranged as described above and connected, one to the support 24h and the other to the right hand saddle sleeve 10.- 'I'he supports 24a, 24h may be welded to the sleeves 10, 10 either before or after attaching the .saddles 28a, 20a to the lamp. The lamp and filament assembly is now mounted on the base I3 by inserting and securing the saddle sleeves 10, 10 in the base terminals I6, I8. The mount thus completed, it is inserted in the outer bulb I2 and sealed in, and the outer bulb is exhausted and sealed oi at I8'. Holes 80, 80 in the sleeves 10, 10 allow their interiors to be exhausted.
Fig. 9 shows a U-lamp Ib like that of Figs. '7 and 8, supported entirely from' the base I8 by a unitary saddle structure 25e, consisting of an (inverted) glass body resembling the body Ill of the base I3, but without the attached terminals I8, I8. The ends of the U-lamp limbs i012, Ib are fused to the upper ends of the nipples I5, I5; but the exhaust tip I8 is left open toA allow of exhausting the outer bulb I2 through the base tip I 8 as usual. The lower filament lead supports 24e, 24e are fused through the bottom of the saddle body 25e, Within or below the saddle 25e, one support 24o is electrically connected to an offset terminal lead I 1c (resembling one of the leads I1 in Figs. 1-3) by a springy helically wound lead wire 82, while the other support 24e has the (left-hand) electrode lead 13 weldedto it.`
II, II are all installed on the saddle 25e, andA their connections completed as far as possible.v
This lamp and filament assembly is then placed over the base I3 and the leads 82 and 13 are ut to length and temporarily pinched to the leads I1c, I1c. Then saddle 25e is separated from base I3 slightly-helical lead portions 82 and 83 stretching to permit this-and the lead 82 is welded to its terminal lead I1c, and the (right- 4 hand) lamp electrode lead '13 is Welded to the otherlead I1c. Then theV saddle 25e is brought down against the base body IQ-the helical lead portions 82 and 83 contracting to obviate any slack-and fused thereto around its periphery.
Themount, thus completed, is inserted in the outer bulb I2 and sealed in, and the latter is then exhausted at I8 and sealed off.
What I claim as new 'and desire to secure by Letters Patent of the United States is:
1. A lamp unit comprising a pluralityof glow discharge vapor lamp tube means close alongy elements coacting with the heat of the lamp tube means and with said outer envelope to heat the lamp tube means substantially uniformly to a temperature sufficient to maintain therein an adequate atmosphere of vaporous working substance with a low glow discharge current density..
2. A lamp unit comprising a plurality of glow discharge vapor lamp tubes close `alongside one another, thus blanketing one anothers heat;-
incandescent filament lengths extending alongside the adjacent unblanketed sides of said lamp tubes, said lamps and said filaments being mounted about and at equal distances from a common centerand in evenly spaced alternate positions about said center; and an evacuated envelope containing said lamp tubes and filament lengths and reflecting and reradiating the filament heat back on the outward-facing tube walls, so as to coact with the heat of the lamp tubes inv heating the tube walls vsubstantially uniformly to a temperature sufficient to maintain therein an adequate atmosphere of vaporous working substance with a -low glow discharge current density.
3. A lamp unit comprising a group of substantially parallel glow discharge vapor lamp tubes; a plurality of incandescent filament lengths connected in series with said lamp tubes as ballast and arranged in` alternation with said lamp tubes at equal distances therefrom and from a common center and substantially parallel with 4. A lamp unit comprising a pair of glow dis-` charge vapor lamp tubes close alongside one an.-
other, thus blanketing one anothers heat; a pair of incandescent lament lengths extending alongsidev said pair of lamp tubes at opposite sides thereof, outside the space between them and at equal distances from a common center; and an evacuated envelope containing saidv lamp tubes and filament lengths in its vacuum space.
5. A lamp unit comprising a plurality of glow discharge vapor lamps containing different working substances which are vaporous in the operation of the lamps and give luminous glow-discharges of different color tones; a plurality of incandescent filament lengths connected in series with said lampsV to ballast them and arranged in o alternation'with the lamps and substantially parallel in direction with their discharge gaps; and
an evacuated envelope enclosing said lamps and filament lengths in its vacuum space, said lamps and said filaments being at equal distances from a common center. 6. A lamp unit comprising a plurality of glow discharge vapor lamps and a plurality of incandescent filaments all connected in series with one another so that the filaments-ballast the lamps and-so that the combination can operate on ordinary standard lighting voltages; the filaments being arranged in alternation with the lamps about and at equal distances from a common, center and being substantially parallel in direction with their discharge gaps, and an evacuated envelope enclosing said filaments and lamps in its vacuum space.
7. A lamp unit comprising an outer evacuated envelope provided with contact terminals at` one end; current leads connected to said ter-` minals and extending inward ,close beside one another, substantially along the `center of the envelope; a 'plurality of tubular glow discharge vapor` lamp tubes in said envelope arranged around said current leads, substantially parallel with them, and supported from them and electrically connectedto" them at their own inner ends; and a plurality of incandescent lament lengths extending parallel with said lamps in f base and terminal structure; current leads attached to the terminals of said structure and extending therefrom side by side; a plurality of glow discharge vapor tubes extending substantially parallel and supported from the inner ends of said current leads and `electrically connected thereto at their own inner ends, and sup` ported at their other ends from said unitary structure; and a plurality of incandescent Illa--` ment lengths having positive temperature resistance coeilicients extending parallel withv said lamps and electrically connected in series with the lamps to' ballast them, said lamps and said laments being in evenly spaced alternate positions about a common center.
9. A lamp unit mount' comprising a unitary base and terminal structure, saddle means mounted thereon, glow discharge vapor lamp means mounted on said saddle means, illament supports and current leads also mounted on said saddle means, and incandescent filament lengths attached and electrically connected to said ilia-` ment supports and current leads, said vapor lamp means and said 'illament lengths being mounted in alternate positions about a common center. y
l0. A lamp and lament assembly comprising a glass saddle structure presenting seats ffor glow discharge vapor lamp tube ends, a glow' discharge vapor lamp tube with its ends mounted on said seats, illament supports and current incandescent ilament lengths attached and electrically connected to said illament supports and current leads, said lamp tube and said nlament lengths being mounted in` alternater positions about a common center.
11, 'I'he combination witha unitary base and terminal structure having a hollowr projecting terminal post, of a glow dischargeavapor lamp,
and a saddle attached to the end of said lamp and comprising a metal support member engaged in said. hollow terminalpost of said base and terminal structure, and electricallyconnected 'to an electrode of said glow discharge vapor lamp.
l2. The combination with a unitary base and terminal structure having a hollow projecting terminal post, oi a saddle comprising a hollow metal support memberA engaged inv said hollow terminal post, and a glow discharge vapor lampl attached.- to said saddle having a current lead extending through said hollow metal member and electrically connected .thereto substantially at its end in said terminal post.
13. A lamp unit comprising an evacuated bulb|` mounted `in said bulb with its leg ends attached to the based end thereof; a current lead attached lamp having its ends attached to said saddle`- 40 means, filament supports and current leads mounted on said saddle means and on the U- tube bend, and incandescent laments attached 'and electrically connected to said filament supports and current leads, the legs or said lamp and saidillaments being at equal distances from a common center.
GEORGE E. INMAN.