Title:
Mercury feeding apparatus
United States Patent 2374304


Abstract:
My invention relates in general to the manufacture of electric discharge lamps or devices of the type comprising a sealed envelope containing a predetermined quantity of a vaporizable metal such as mercury. More particularly, my invention relates to method and apparatus for introducing a predetermined...



Inventors:
Owings, Charles E.
Application Number:
US51247143A
Publication Date:
04/24/1945
Filing Date:
12/01/1943
Assignee:
GEN ELECTRIC
Primary Class:
Other Classes:
141/9
International Classes:
H01J9/395
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Description:

My invention relates in general to the manufacture of electric discharge lamps or devices of the type comprising a sealed envelope containing a predetermined quantity of a vaporizable metal such as mercury. More particularly, my invention relates to method and apparatus for introducing a predetermined quantity of vaporizable metal into the envelope of such devices.

In the manufacture of electric discharge lamps of the well-known fluorescent type in general use at present, a quantity of mercury is introduced into the lamp envelope during the lamp exhausting operation. To insure a properly performing lamp, the quantity of mercury which actually passes into and remcins within the lamp envelope must be at or above a certain minimum amount.

In the usual type of exhausting and mercury filling machine employed in the manufacture of such fluorescent lamps, the electrodes of the lamp are heated following the mercury filling operation by an electrical current passing through the electrodes. The mercury is introduced into the envelope by means of an injecting device or dispenser which deposits a measured amount of mercury into a vertical conduit communicating with the interior of the envelope, the mercury dropping through the conduit into the envelope and lodging within the lower end of the latter where it is vaporized by reason of the heated condition of the envelope and electrode at the lower end of the lamp. If the mercury released by the dispenser into the conduit actually passes into the lamp envelope, an arc will eventually strike across the ends of each of the energized lamp electrodes due to the lower resistance of the mercury vapor arc path thereacross. Such a local arc discharge thus causes an end glow to develop within the lamp envelope. For various reasons, however, such as failure of the mercury dispenser to operate properly or lodging of the mercury elsewhere, a sufficient amount of the mercury released by the dispenser does not always pass into the lamp envelope with the result that it is frequently necessary for the operator to perform additional manually-controlled mercury injecting operations, as,by hand switches. The determination of whether or not additional mercury is to be introduced into a lamp by the operation of such manually-controlled injecting means therefore requires the constant observance by the operator of either the lamps being processed or of suitable indicator means.' One object of my invention is to provide a method and apparatus for automatically introducing into the envelope of an electric discharge device a predetermined minimum quantity of a vaporizable metal.

Another object of my invention is to provide a mercury vapor lamp exhaust apparatus having means for automatically effecting the introduction of additional amounts of mercury into the lamp envelope in the event a predetermined minimum amount of mercury is not initially introduced thereinto.

Still another object of my invention is to provide an indexing type lamp exhaust machine having, in combination, means for automatically feeding a predetermined quantity of mercury to the envelope of a lamp when positioned at one of the stations of said machine together with additional means for automatically effecting the introduction at a subsequent station of additional amounts of mercury into the lamp envelope in the event that a predetermineed minimum amount of mercury is not then present in the lamp.

A feature of the invention is the provision of means controlled by electrical conditions existing within the lamp envelope for effecting.the automatic introduction of the additional. mercury into the lamp envelope.

Further objects and advantages of my invention will appear from the following description of a species thereof and from the accompanying drawing in which: Fig. 1 is a diagrammatic representation of an exhaust machine head with associated control means comprising my invention for supplying additional mercury to a lamp in the head; and Fig. 2 is a fragmentary plan view of such exhaust machine with one of the heads thereof partly broken away to show the pinch clamp mechanism of said head.

Referring to the drawing, the apparatus comprising my invention is there shown as applied to a lamp exhaust machine of the type described and claimed in United States Patent No.

2,247,513-A. J. Marshaus, issued July 1, 1941, and comprising a carrier or turret 10 having a plurality of heads II which are mounted at regularly spaced intervals about the periphery of the turret and are advanced in turn through a similar number of stations by counterclockwise indexing movements of the turret. As shown in Fig. 1, each head II is provided with suitable holders 12 for carrying an electric discharge lamp 13 which may be of the well-known fluorescent type in general use at present and comprising a tubular glass envelope 14 having a pair of filamentary hot cathodes or electrodes 15, 15' sealed within the opposite ends thereof and a separate pair of lead-in wires 6I, 18 and 18', IS' connected, respectively, to each cathode and extending out through each end of the envelope.

The cathodes 15, 15' each have a resistance such that the potential drop thereacross exceeds the ionizing potential of mercury. The envelope 14 is completely sealed except for, the opening through an exhaust tube I1 extending from one end of the envelope. The lamp 13 is held by the holders 12 in a vertical position in the head II with the exhaust tube 17 uppermost and extending into a compression rubber chuck 18 mounted on the lower end of an exhaust head 19. The chuck 18 is provided with a compressible rubber ring 20 which is mounted within the chuck housing 21 and is compressed tightly around the exhaust tube 17 to thereby provide an airtight connection between the exhaust tube and the chuck housing 21. The rubber ring is compressed by rotation of a cap 22 threaded onto the chuck housing 21, the said cap pressing a metal guide washer 23 up against the underside of the rubber ring through ball bearings 24 interposed between the cap and washer.

The chuck housing 21 is provided with an exhaust passageway 25 in axial alignment with both the exhaust tube IT and a vertically extending passageway 26 in the exhaust head 19.

The said exhaust passageway 26 is formed, in part, by the opening through a rubber tube 27 disposed longitudinally within the exhaust head, and is connected to suitable exhausting means, such as a vacuum pump, through a connection pipe or conduit 28 and a rotary valve mechanism (not shown), as described in the previously mentioned Marshaus patent. In case there be no lamp in the head II, the operator can close or pinch off the passageway 26 in the exhaust head 19 by means of. a pinch clamp comprisink a pressure member 29 and an actuating cam or lever 30 for pressing the pressure member 29 against the rubber tube 27 to flatten the same and thus close or pinch off the passageway therethrough. The pressure member 29 and the cam lever 30 are pivotally mounted on the exhaust head 19 within a slot 3I therein. In the inoperative or open position of the pinch clamp wherein the rubber tube 27 is left open, the pinch clamp actuating lever or cam 31 occupies an "out" position (as shown in full lines in Fig. 2) wherein it is further removed from the center of rotation of the turret 10 than it is when in its closed or "in" position indicated in dotted lines in Fig. 2.

Each exhaust head 19 is provided at the top thereof with a separate mercury feeding or injector device 32 for discharging a measured amount of mercury into the vertical exhaust passageway 26 in the head 19, the mercury then passing down through the said passageway and through the exhaust tube I1 into the lamp envelope 14. The mercury feeding device 32 may be of any suitable form but preferably is of the electrically actuated type disclosed and claimed in copending U. S. patent application Serial No. 504,716, filed October 2, 1943, by E. B. Isaac et al., and comprises a hermetically sealed reservoir or container 11 which is filled with a quantity of mercury 34 or other vaporizable metal and is mounted on top the exhaust head 19 with a discharge passageway 35 at the bottom of the reservoir, in airtight communication with the exhaust passageway 26 in the exhaust head. A hollow slide or feed member 36, having a small pocket or recess 37 in its outer side for holding a predetermined amount of mercury, extends through and has a free but sufficiently close sliding fit in the restricted upper end portion 38 of the discharge passageway 35 to form an effective mercurytight seal therebetween. The said slide member 36 is vertically reciprocable in the reservoir 33 to first introduce the recessed portion 37 thereof into the mercury pool 34 so as to allow the recess 37 to fill with mercury and to then withdraw the recessed portion down through and beyond the lower end of the restricted portion 38 of the discharge passageway 35 to thereby allow the mercury trapped in the recess to drop out of said recess and into the exhaust passageway 26. The slide member 36 extends up through the reservoir 33 and is connected at its upper end to a soft iron or steel piston 39 which reciprocates within a bell housing 40 made of non-magnetic material and attached to the upper end of the reservoir in an airtight manner.

During the course of its movement around the machine the lamp 13 is exhausted while it moves through an oven, after which it is indexed to a, main mercury feeding station A (Fig. 2) where the mercury feeding device 32 is operated to feed a measured quantity of mercury into the lamp envelope 14 while.the latter is in a more or less evacuated condition and is connected to the exhausting means through pipe 28. The operation of the mercury feeding device 32 is effected by the energization of a coil 41 (Fig. 2) which is lowered over the bell housing 40 of the device at the said station A and is energized one or more 85 times, depending upon the amount of mercury . to be introduced into the lamp. The magnetic field produced by the energized coil 41 attracts and raises the piston 39 in the bell housing so as to move the slide member 36 upwardly from O4 its normal lowered position and introduce the pocket 13 thereof into the pool of mercury 34 In the reservoir 33. After a brief interval of time sufficient to allow the pocket 37 to fill with mercury from the pool 34, the coil 41 is de-energized to allow the slide member 36 to fall freely of its own weight and carry the mercury in the pocket 37 down through and beyond the restricted portion 38 of the discharge passageway 35 where it drops out of said pocket into the passageway 26 and thence down through the said passageway and exhaust tube 17 into the lamp envelope.

The required amount of mercury for each lamp Sis made up by one or more actuations of the slide member 36.

During the interval when the lamp 13 is positioned at the mercury feeding station A, the cathodes 15. 15' thereof, which are coated with electron emissive material such as alkaline earth carbonates, are continuously heated, to activate the same by breaking the carbonates down to oxides, by the passage of an electrical current therethrough from separate cathode heating circuits 42, 42'. The current is supplied to each of Sthe cathodes 15, I5' by means of a pair of curved plate-shaped track contacts 43, 43 and 43', 43' against which the lamp lead-in wires 16, IS' wipe during the index of the lamp to station A and while it is positioned at said station. The track contacts 43 or 43' for each cathode are connected through separate ballasts 44, 44' respectively, in the form of incandescent lamps, to a suitable source of current supply. When the current flows through the cathodes IS, IS', the ballast lamps 44, 44' burn with relatively low brightness.

Upon entering the lamp envelope 14, the mercury fed to the lamp at station A by the feeding device 82 drops through the said envelope and lodges at the bottom thereof where it is then vaporized by the heat from the lowermost cathode 5I and from the glass envelope itself, the lower end of the envelope then being at a temperature ranging from approximately 200* to 250° C. Due to the relatively slow rate of evacuation of the. envelope, a mercury vapor atmosphere is then created therein. As a result, a mercury vapor arc discharge will shortly strike first across the ends of the lowermost cathode 15 and then across the uppermost cathode 15' due to the lower resistance of the mercury vapor arc path across each cathode as compared to the resistance of the cathode itself. The resulting drop in resistance in the cathode heating circuits 42, 42' which thus occurs when the local arc discharge strikes across the individual cathodes 15. 15' then causes the current flowing in the said circuits to increase and the incandescent ballast lamps 44, 44' to burn with appreciably greater brightness than theretofore.

Inasmuch as the current intensity of the local arc discharge, and thus the current flow through and therefore the brightness of the ballast lamp 44 or 44', increase as the mercury vapor pressure within the envelope increases, the relative brightness of the ballast lamp 44 or 44' at any given instant is therefore a direct indication of the mercury vapor pressure existing at that particular instant within the envelope and therefore an indication that mercury is present in the envelope in an amount at least equal to the amount required to establish such a pressure.

Thus, when the ballast lamp 44 or 44' attains at least a predetermined level of brightness, such condition then denotes the presence of at least a predetermined amount of mercury within the lamp envelope.

To insure the production of properly performing lamps, it is necessary that mercury be present in the lamp envelope 14 in an amount at least equal to a predetermined minimum amount.

The mercury feeding device 32 is therefore arranged to feed to the envelope at station A a quantity of mercury equal to. but preferably somewhat in excess of, the said predetermined minimum amount. If all or a sufficient quantity of the mercury thus released by the feeding device 32 at station A actually enters the lamp envelope so that the said envelope then contains such predetermined minimum amount of mercury, then the mercury vapor created in the lamp envelope by the vaporization of the mercury therein will shortly attain a predetermined minimum pressure value sufficient to support a local arc discharge of predetermined minimum intensity across each of the cathodes 15, 15'. For various reasons, however, such as the failure of the mercury feeding device 32 to operate properly or lodging of the mercury elsewhere, the amount of mercury which actually enters the lamp at station A is sometimes less than the said predetermined minimum amount. The failure of the local arc discharge either to form at the cathodes !5, 15' or to reach a predetermined minimum intensity is therefore an indication that there is either no mercury at all, or less than the required minimum amount of mercury, in the lamp envelope 14.

In accordance with the invention, auxiliary mercury feeding means are provided for automatically feeding additional amounts of mercury into the lamp envelope in the event such a mer6 cury deficiency condition exists therein as indicated either by the total absence of a local arc discharge or by the absence of a discharge of predetermined minimum intensity, at one or both .cathodes IB, 16', the operation of such auxiliary mercury feeding means being governed by suitable control means the operation of which is controlled, in turn, by the presence or absence of a local arc discharge of such predetermined minimum intensity at one or both lamp cathodes. The introduction of the additional amounts of mercury into the lamp envelope 14 may take place at any time after the lapse of a definite period of time during which a local arc discharge of such predetermined minimum intensity would be So. normally expected to occur at one or both cathodes 15, 15'. Preferably, however, the additional mercury is introduced while the lamp is positioned at the next succeeding station B (Fig. 2) since by that time a local arc discharge of the g2 said predetermined minimum intensity normally should be present at least at the lowermost cathode 15 if the required minimum amount of mercury is present in the lamp envelope.

The auxiliary mercury feeding arrangement according to the invention comprises, in general, means for automatically operating the mercury feeding or injector device 32 on the exhaust head 19 one or more additional times when no local arc discharge, or a discharge of less than the re5 quired minimum intensity, is present at one or both lamp cathodes. In the particular form of the invention illustrated, the auxiliary mercury feeding arrangement comprises a solenoid coil 45, similar to the coil 41 at station A, which is lowered over the bell housing 40 of the mercury injector 32 as soon as the latter is positioned at station B. The lowering and raising of the coil 45 is effected by. the change in shape of a cam 46 mounted on the main drive shaft 47 of the machine and engaging one end of a follower lever or rocker arm'48 the other end of which is connected to a vertical rod 49 to which the coil 45 is fastened by an arm 50 of insulating material. The coil 45 is connected by leads 51, 52 and 53 to a suitable source of electrical current to Sthereby form an energizing circuit 54 for the said coll. The said solenoid circuit 54 is normally maintained in an open-circuit condition by an interrupting switch 55. A cam 56, mounted on the main drive shaft 47 and having one or more lifts or steps 57 (preferably three, as shown), intermittently closes the said switch 55 for brief intervals, while the coil 45 is in its lowered position around the bell housing 40, to thereby intermittently operate the mercury injector 32 so as to feed additional amounts of mercury to the lamp envelope 14.

Connected in the solenoid circuit 54 is a suitable relay device 58 for opening the said circuit when a mercury vapor arc discharge of the aforesa:d predetermined minimum intensity exists in the lamp 13 across one of the lamp cathodes 15, 15', preferably the lowermost cathode 15.

The said relay 58 may be of any suitable type which is responsive to conditions attending the existence, of such a predetermined intensity arc discharge in the lamp to thereby interrupt the solenoid circuit 54. Thus, the relay 58 may be of the current-sensitive type which is actuated by a predetermined minimum current flowing therethrough, the relay being set, for the purposes of the invention, to operate only when the current flow in the cathode heating circuit 42 or 42' and through the relay equals or exceeds a predetermined value as determined by the existence of a local arc discharge of the aforesaid predetermined minimum intensity at the cathode 15 or 15'. Preferably, however, the relay 58 is of the photoelectric type which is actuated by an increase in the intensity of the light striking the photoelectric cell or tube of the relay. Such a photoelectric relay may be of the well-known commercial types in use at present and it is preferably actuated by the increased light from one or the other of the ballast lamps 44, 44' in the cathode heating circuits 42, 42', the relay being set to operate only when the light from the ballast lamp 44 or 44' equals or exceeds a predetermined brightness as determined by the existence of a local arc discharge of the' aforesaid predetermined minimum intensity at the cathode 15 or 15'. For adjusting the intensity of the light that operates the photoelectric relay, suitable means are provided such as electrical variables (for instance a resistance) connected in the circuit of the relay itself, or an adjustable or iris diaphragm 59 interposed between the exciting ballast lamp 44 or 44' and the photoelectric element of the relay 58. If desired, the separate indicator or ballast lamp or lamps may be omitted, and the uhotoelectric relay operated directly by the brilliance of the end glow in the lamp. In that event, a bright glow of predetermined minimum intensity, due to an arc discharge of the required minimum intensity, indicates ample mercury, and 3~ less brilliance due merely to incandescence of the cathode, indicates a deficiency of mercury.

The difference in color of the end glow may also be utilized; a blue glow indicating the presence of sufficient mercury, whereas a deficiency of mercury is indicated by the ordinary yellowish-red incandescent glow.

In the particular, preferred embodiment illustrated, the relay 58 is of the photoelectric type and is actuated by the ballast lamp 44 in the heating circuit 42 for the lowermost cathode IS.

The relay 58 comprises a photoelectric tube 60, a relay coil 61, and an armature 62 forming a switch connected in the solenoid circuit 54 and actuated by the relay coil. The relay armature or switch 62 is normally maintained in a closedaircuit position as shown. and is opened only when the photoelectric tube 60 is excited by the ballast lamp 44 to thereby energize the relay coil 61 and so pull the armature 62 away from the relay switch contact 63.

During substantially the entire index movement of the lamp 13 from station A to the auxiliary mercury feeding station B, and also while it is positioned at the said station B, the lamp lead-in wires 16, 16' ride along and encage the track contacts 43, 43' to thereby maintain the cathode heating circu'ts 42, 42' closed and therefore the cathodes IS, 15' heated. If at least the required minimum amount of mercury has actually entered the lamp envelope 14 at the main mercury filling station A, then the substantially continuous heating of the cathodes 15. I5' between stations A and B serves to maintain the mercury in the lamp in a continuously vaporized state to thereby support a mercury vapor arc discharge of the aforesa'd predetermined -minimum intensity across the lowermost cathode 15 during the index of the lamp to station B and while it is positioned thereat.

If upon reaching the auxiliary mercury feeding station B a local arc discharge of the said predetermined minimum intensity persists across the lowermost lamp cathode 15, the ballast lamp 44, because of its greatly increased brightness, will excite the photoelectric tube 60 of the relay 58 thus causing the relay switch 62 to open and thus break the solenoid circuit 54 so as to prevent operation of the mercury injector 32 at station B. However, if there be no local arc discharge across the lowermost cathode 15 when the lamp reaches station B, or if a discharge of less than the aforesaid predetermined intensity is present, then the ballast lamp 44, because of its relatively low or insufficient brightness, fails to excite the, photoelectric tube 60 sufficiently to cause the relay switch 62 to open. As a result, the said switch 62 remains in its normal closed-circuit position so that when the operating switch 55 in the solenoid circuit 54 is subsequently closed by the first step 57 on the cam 56, the solenoid circuit is completed and the mercury injector 32 operated once to feed a definite amount of mercury into the lamp envelope. If, after the introduction of such additional mercury into the lamp envelope, a mercury vapor discharge of the required minimum intensity should develop across the lowermost cathode I5, then the ballast lamp 44 will emit sufficient light to actuate the relay 58 and open the solenoid circuit 54 so as to prevent further operation of the mercury injector 32. However, if a mercury vapor arc discharge of the required minimum intensity still fails to occur across the lowermost cathode 15, then the photoelectric relay 58 remains unactuated and the relay switch 62 remains closed. As a result, the injector 32 is operated a second time, upon closure of the switch 55 by the second step 57 on cam 56, to thereby supply a second shot of mercury to the lamp 13.

If, after this second shot of mercury, a mercury vapor arc discharge of the required minimum intensity still fails to develop across the lowermost cathode 15 so that the relay 58 still remains unactuated, then the injector is operated a third time, by the closure of switch 55 by the third step on cam 56, to thereby supply a third shot of mercury to the lamp.

The three additional shots of mercury automatically supplied by the injector 32 at the auxiliary mercury feeding station B should result in the introduction of sufficient mercury into the lamp envelope 14 to cause the formation of a mercury vapor arc discharge of the required predetermined minimum intensity across the lowermost lamp cathode 15 in practically all cases.

If such an arc discharge fails to occur after the three additional actuations of the mercury injector device 32 at station B, then such failure is an indication either that the lamp itself is defective or that the mercury injector device 32 is not operating properly.

To prevent the operation of the auxiliary mercury injection arrangement at station B in the event there be no lamp present in the head I, the solenoid circuit 54 is preferably provided with a suitable cutout switch 64 for interrupting the said circuit when such condition exists. The said switch 64 is preferably actuated by the pinch clamp lever 30, the switch normally being in an open-circuit position and being engaged by the pinch clamp operating lever 30 when the latter is in its "out" position (indicating the presence of a lamp in the head) to thereby close the switch during the interval when the head I is positioned at station B. The switch 64 may be mounted on an arm 65 extending from the stationary standard 66 through which the solenoid coil support rod 49 extends, the switch being located in a position in the path of the rotary travel of the pinch clamp lever 30, when the latter is in its "out" position as shown in Fig. 2, so as to be engaged and actuated thereby when in such position. If desired, a suitable indicator lamp 61 may be connected in the solenoid circuit 54 in parallel with the solenoid coil 45 for the purpose of indicating whether or not the auxiliary mercury feeding arrangement is operating to supply additional mercury to the lamp at station B.

What I claim as new and desire to secure by Letters Patent of the United States is: 1. In combination, means for feeding a quantity of vaporizable metal into an envelope, means for vaporizing the vaporizable metal introduced into the envelope, means including an electrical circuit for establishing an arc discharge through the metal vapor, means controlled by said electrical circuit for detecting the existence of a discharge of predetermined minimum intensity, and means controlled by the detecting means for operating the said feed means to feed an additional amount of the vaporizable metal into the envelope upon nonexistence of such a minimum intensity discharge.

2. In combination, means for feeding a quantity of vaporizable metal into an envelope, means for vaporizing the vaporizable metal introduced into the envelope, means including an electrical circuit for establishing an arc discharge through the metal vapor, said electrical circuit including an electric lamp connected therein to provide an indication of the existence of an arc discharge of predetermined minimum intensity, and means controlled by the light output of said lamp for operating the said feed means to feed an additional amount of the vaporizable metal into the envelope upon non-existence of such a minimum intensity discharge.

3. In combination, means for feeding a quantity of vaporizable metal into an envelope, actuating means for the feed means, means for vaporizing the vaporizable metal introduced into the envelope, means including an electrical circuit for establishing an arc discharge through the metal vapor, said electrical circuit including an electric lamp connected therein to provide an indication of the existence of an arc discharge of predetermined minimum intensity, and photoelectric relay means responsive to the light output of said lamp for controlling the operation of said actuating means to cause the feeding of an additional amount of the vaporizable metal into the envelope by the said feed means upon nonexistence of such a minimum intensity discharge.

4. In combination, electrically actuated means for feeding a quantity of vaporizable metal into an envelope, means including an electrical actuating circuit for operating the feed means, means for vaporizing the vaporizable metal introduced into the envelope, means including an electrical circuit for establishing an arc discharge through the metal vapor, and means controlled by the said last-named arc establishing circuit for controlling the operation of said actuating circuit to cause the feeding of an additional amount of the vaporizable metal into the envelope by the said feed means upon nonexistence of a discharge of predetermined minimum intensity.

5. In combination, means for feeding a quantity of vaporizable metal into an envelope, means for vaporizing the vaporizable metal introduced into the envelope and for establishing an arc discharge through the metal vapor, said last-named means comprising an electrical heating element in the envelope and an electrical circuit for said heating element, and means controlled by the nonexistence of a discharge of predetermined minimum intensity for operating the said feed means to feed an additional amount of the vaporizable metal into the envelope.

6. In combination, means for feeding a quantity of vaporizable metal into an envelope, means for vaporizing the vaporizable metal introduced into the envelope and for establishing an arc discharge through the metal vapor, said last-named means comprising an electrical heating element in the envelope and an electrical circuit for said heating element, and means controlled by said electrical circuit for operating the said feed means to feed an additional amount of the vaporizable metal into the envelope upon nonexistence of a discharge of predetermined minimum intensity.

7. In combination, means for feeding a quantity of vaporizable metal into an envelope, means for vaporizing the vaporizable metal introduced into the envelope and for establishing an arc discharge through the metal vapor, said last-named means comprising an electrical heating element in the envelope and an electrical circuit for said element including an electric lamp connected to provide an indication of the presence of a discharge of predetermined minimum intensity, and -means controlled by the light output of said lamp for operating the said feed means to feed an additional amount of the vaporizable metal into the envelope upon nonexistence of such a minimum intensity discharge.

8. In combination, electromagnetically actuated feed means for feeding a quantity of vaporizable metal into an envelope, an electrical actuating circuit including a solenoid for operating said feed means, means for vaporizing the vaporizable metal introduced into the envelope, means including an electrical circuit for establishing an arc discharge through the metal vapor, and means controlled by the said last-named arc-establishing circuit for controlling the operation of the solenoid actuating circuit to cause the feeding of an additional amount of the vaporizable metal into the envelope by the said feed means upon nonexistence of a discharge of predetermined minimum intensity.

9. In combination, electromagnetically actuated feed means for feeding a quantity of vaporizable metal into an envelope, an electrical actuating circuit including a solenoid for operating said feed means, means for vaporizing the vaporizable metal introduced into the envelope and for establishing an arc discharge through the metal vapor, said last-named means comprising an electrical heating element in the envelope and an electrical heating circuit for said element, and means controlled by said heating circuit for controlling the operation of the solenoid circuit to 85 cause the feeding of an additional amount of the vaporizable metal into the envelope by the said feed means upon nonexistence of a discharge predetermined minimum intensity.

10. In combination, electrically actuated apparatus for automatically feeding mercury into the envelope of an electrical device containing a resistance heating element, means for effecting a repeat operation of the feeding apparatus w.Xen its initial operation fails to introduce sufficient mercury into the enevelope comprising an electrical circuit including an electric lamp connected in series with said heating element to a current source so that said heating element is heated to establish thereacross an arc discharge through the mercury vapor whereby said lamp is lighted to a lower lever of brilliance when current is passing through the heating element and to a higher predetermined level when an arc is established, and light-sensitive relay means responsive to the light emitted by said lamp and connected to effect a repeat operation of the feeding apparatus only upon failure of the lamp to be lighted to the higher predetermined level of brilliance.

11. An indexing type lamp exhaust apparatus comprising, in combination, a carrier member having a lamp-supporting head mounted thereon and indexed thereby to a plurality of work stations, mercury feed means on said head for feeding mercury into a lamp mounted in the head, actuating means at one of said stations for operating said feed means to thereby feed a quantity of mercury to the lamp, means at a subsequent station for determining the presence or absence of a predetermined minimum amount of mercury in the lamp, and means controlled by said last-named means for operating the said feed means at said subsequent station to feed an additional amount of mercury to the lamp when less than the said minimum amount of mercury is present therein.

12. An indexing type lamp exhaust apparatus comprising, in combination, a carrier member having a lamp-supporting head mounted thereon and indexed thereby to a plurality of work stations, electrically actuated mercury feed means on said head for feeding mercury into a lamp mounted in the head, electrical actuating means for operating said feed means at one of said stations to thereby feed a quantity of mercury to the lamp, means for vaporizing the vaporizable metal introduced into the envelope, means including an electrical circuit for establishing an arc discharge through the mercury vapor in the lamp at a subsequent station, auxa iliary actuating means for operating said feed means at the said subsequent station, and means controlled by the arc-establishing circuit for controlling the operation of said auxiliary actuating means to cause the feeding of an additional amount of mercury to the lamp by the said feed means upon nonexistence of an arc discharge of predetermined minimum intensity in the lamp at the said subsequent station.

13. An indexing type lamp exhaust apparatus comprising, in combination, a carrier member having a lamp-supporting head mounted thereon and indexed thereby to a plurality of work stations, an electromagnetically actuated mercury feeding device on said head for feeding mercury into a lamp mounted in the head, electromagnetic actuating means for operating said feeding device at one of said stations to thereby feed a quantity of mercury to the lamp, means for vaporizing the vaporizable metal introduced into the envelope, means including a cathode in the lamp and an electrical heating circuit for said cathode for establishing an are discharge through the mercury vapor in the lamp at a subsequent station, auxiliary electromagnetic actuating means including an electrical actuating circuit for operating said feed means at the said subsequent station, and a relay connected in said actuating circuit and controlled by the said heating circuit for controlling the operation of said auxiliary actuating means to cause the feeding of an additional amount of mercury to the lamp by the said feed means upon nonexistence of an arc discharge of predetermined minimum intensity in the lamp at the said subsequent station.

CHARLES E. OWINGS.