US3904916A

US3904916A - End cap structures for fluorescent lamps

Info

Publication number: US3904916A
Application number: US370377A
Authority: US
Inventors: Thomas J Emidy; Donald P Northrop; Luke Thorington; Andrew Henry Olsen
Original assignee: Duro Test Corp
Current assignee: Duro Test Corp
Priority date: 1971-03-15
Filing date: 1973-06-15
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09

Abstract

A fluorescent lamp having end caps with electrical contact members mounted directly thereon through which the lamp is to be connected to a fixture to supply current to the lamp, and in which the mounting leads for the cathode of each end cap are connected directly to these electrical contacts. The end caps are also formed to accept an end of the envelope of a fluorescent lamp for direct attachment thereto. In a further embodiment of the invention an end cap is provided having a tubulation which can be sealed by infra-red energy.

Description

United States Patent Emidy et a1. Sept. 9, 1975 END CAP STRUCTURES FOR 2,556,059 6/1951 Braunsdorfi' 313/318 FLUORESCENT LAWS 3,551,725 12/1970 Brundige 3,602,755 8/1971 Hoeh 313 109 Inventors: Thomas J. Emidy, Morris Plains; Donald P. Northrop, Glen Rock; Luke Thorington, Berkeley Heights; Andrew Henry Olsen, Jersey City, all of NJ.

Assignee: Duro-Test Corporation, North Bergen, NJ.

Filed: June 15, 1973 Appl. No.: 370,377

Related US. Application Data Division of Ser. No. 124,311, March 15, 1971, Pat. No. 3,749,167.

US. Cl 313/493; 313/220 Int. Cl. H01J 63/04 Field of Search 313/220, 109, 493; 316/19;

[56] References Cited UNITED STATES PATENTS 2,273,960 2/1942 Hopkin 313/109 FOREIGN PATENTS OR APPLICATIONS 1,129,865 10/1968 United Kingdom 313/220 Primary Examiner-R. V. Rolinec Assistant Examiner--Darwin R. Hostetter Attorney, Agent, or F [rm-Darby & Darby [5 7 ABSTRACT A fluorescent lamp having end caps with electrical contact members mounted directly thereon through which the lamp is to be connected to a fixture to supply current to the lamp, and in which the mounting leads for the cathode of each end cap are connected directly to these electrical contacts. The end caps are also formed to accept an end of the envelope of a fluorescent lamp for direct attachment thereto. in a further embodiment of the invention an end cap is provided having a tubulation which can be sealed by infra-red energy.

18 Claims, 7 Drawing Figures PATENTED 91975 $904,916

sum 2 0f 3 FIG. 6

PATENTEBSEP 9197s 3,904,916

sum 3 o 3 Q COAT AND LEHR BULBS r I SUPPLY SUPPLY END CAPS END CAPS END CAPS VACUUM EXHAUST 2 AND BAKE FLUSH AND 2|8 1/- FILL WITH INERT GAS BOTH 220 ELECTRODES TPsPER P ING PRESSURE 222 ADD MERCURY IR SEAL TUBULATIONS'TT/ 225 CONDUCT TO ATMOSPHERE END CAP STRUCTURES FOR FLUORESCENT LAMPS This application is a division of ourprior copending application, Ser. No. 124,31 1 filed Mar. 1 5, 1971.m1- tled Fluorescent Lamps and Method of Manufacturing Same, now US. Pat. No. 3.749,l67.

Conventional fluorescent lamps utilize a structure at each end thereof for holding the cathodeor electrode and for supplying currentto the lamp. In a conventional electrode structure, a glass stem is provided which has a flared lower end which isseale'd to the inner surface of the lamp envelope. In one type of lamp, the stem at one end of the envelope also includes an opening which communicates with the interior of the lamp envelope. The opening is the termination of an exhaust tube, or tubulation, which has a tip which extends outside the lamp envelope. In some lamps a stem with a tubulation is used at each end'of the envelope. v

In conventional lamps the stem also holds a pair of lead wires which are connected on the end of the'stei'n opposite from the flare to a pair of mounting members to which the cathode is electrically connected. These lead wires extend out of the flared end of the stem. A base is also provided having external contact, pins to which the lead wires are connected and which are used to connect and hold the lamp in a fixture.

In accordance with conventional manufacturing processes for prior art lamps with stems, one or both of which has a tubulation, the lamp is normally exhausted of air through one of the tubulation members at an end of the envelope, even though the lamp may have two such tubulation members. The lamp is also filled with mercury and the necessary fill gas through one of the tubulations and one or both tuhulations, depending upon the lamp structure, is then sealed or tipped off. A base is then sealed to each end of the lamp.

The present invention is directed to novel types of fluorescent lamps and processes for making the same. In accordance with the invention, several processes are disclosed for the manufacture of fluorescent lamps in which the lamp envelope is exhausted, then flushed and filled with gas through both ends of the lamp envelope simultaneously. This results in afaster and more cleaner exhaust and filling operation since any impurities in the envelope do not travel the complete length of the envelope. In addition, the lamps utilize novel end cap structures which. in a preferred embodiment of the invention, are formed to have the contact pins and lead wires for the cathode directly thereon. These end cap structures also are constructed so as to accept an end of the envelope of the fluorescent lamp so that it can be held to the end cap. The preferred embodiment of process of manufacturing lamps using these end caps is such that the cathodes can be activated external to the envelope during processing, thereby avoiding contamination of the lamp. In addition, an end cap is disclosed having a tubulation with the tubulation being formed of an infra-red energy absorbing glass so that the tubulation can be sealed by radiant heating. I

It is therefore an object of the present invention to provide novel fluorescent lamps and methods of making the same. i

Another object is to provide methods'for manufacturing fluorescent lamps in which the lamp envelope during processing is filled and exhausted simultaneously through both ends of the envelope.

, An additional object is to provide a novel process for manufacturing lamps in which the cathodes are activated external to the envelope to avoid contaminating the envelope.

Another object is to provide end caps for fluorescent lamps in which the electrical contacts for the lamp and the cathode mounting leads are mounted directly to the end cap.

A further object is to provide fluorescent lamps the ends of whose envelopes are directly attachable and scalable to end caps which have electrical contact members and cathode mounting leads fastened directly thereto.

A further object is to provide an end cap for fluorescent lamps in which the tubulation member is formed of an infra-red absorbing material.

Yet another object is to provide an end cap for fluorescent lamps having contact members and cathode mounting leads connected directly, in which a tubulation member is also formed directly in the end cap.

Other objects and advantages of the present invention will become more apparent upon reference to the following specification and annexed drawings, in which:

FIG. 1 is a flow diagram of a preferred embodiment of one process for making a lamp in accordance with the subject invention;

FIG. 2 is a side elevational view, partially in crosssection, ofa lamp manufactured in accordance with the process of FIG. 1, using a preferred form of end cap;

FIGS. 3 and 3A are a side elevational view and top view respectively taken partially in cross-section showing another embodiment of end cap for use with lamps manufactured in accordance with the process of FIG.

FIG. 4 is a side elevational view of a lamp using an end cap which is manufactured in accordance with the process of FIG. 5;

FIG. 5 is a flow diagram of another process for making fluorescent lamps in accordance with the subject invention; and

FIG. 6 is a side elevational view of another form of end cap for use with the process of FIG. 5.

FIG. 1 is a flow diagram of a preferred embodiment of the process for the manufacture of fluorescent lamps. FIG. 2 shows a portion of one form of lamp manufactured according to the process of FIG. I having a novel end cap with cathode structure. The end cap' structure is described before describing the process of FIG. 1.

The end cap of FIG. 2, includes a circular base 30, of glass or other suitable material which is formed with a pair of

upstanding bosses

32 and 34 on the inner surface thereof. Electrically conductive cathode mounting leads 36 and 38 are respectively located in the

bosses

32 and 34. Each mounting lead has a slit 36' and 38' in the top end thereof. The ends of filament 40 are located in the

slits

36 and 38 which are then crimped to make the electrical contact.

The lower ends of the

leads

36 and 38 are of somewhat larger diameter and are located in holes or circular grooves 45 in the bottom of the base to serve as the contact pins. Thus, a simple construction is provided where the cathode leads and contact pins are formed as one-piece units. In assembling the cathode leads and the contact pins to the end cap, it is only necessary to push the cathode mounting ends first through the holes in the

bosses

32 and 34. When they are in position with the shoulders of the enlarged diameter portions against the top wall of the circular grooves 45, the

members

36 and 38 are then sealed to the base by a suitable sealant, for example, glass frit.

As shown in FIG. 2, the circumferential portion of the base is formed with

upstanding walls

54 and 55 defining a groove 56 therebetween. The outer wall 54 is of a greater height than the inner wall 55. Also, the outer wall 54 has a tapered inner edge 57 which is shaped to conform to a shouldered down curved portion 60 on the end of a bulb 62 of a fluorescent lamp. This shouldered down curved portion 60 terminates in an end 64 which rests on the bottom wall of the groove 56. The curved end 60 of the bulb fits in the groove 46, and the solder material is applied therearound to seal the bulb to the end cap by a conventional lamp sealing process.

Referring now to FIG. 1, the process for making the lamp of FIG. 2 is described. While the process can be carried out one lamp at a time, it is preferred that the process be sequential so that a plurality of bulbs for the lamps are sequentially fed into the input of the process and the completed lamps sequentially come out of the output end of the system. Also, the process is such that assembled end caps holding the cathodes are also supplied to the system at the same time. The equipment for performing the sequential process is not described in detail. However, in general, it includes a plurality of chambers having different pressures and/or gases through which the lamps are conveyed on a suitable conveyor system. The chambers are such that the various operations required can be carried out with the lamps in the chamber, i.e. gas flushing, attaching of end caps, etc. either manually or automatically. The necessary air locks, buffer chambers, etc., are present between the chambers. These are conventional.

As a first step 100 in the process of FIG. 1, the interiers of the bulbs are coated with the desired phosphor mix. Next, in step 102, the ends of the bulbs are cleaned off so that the end caps can be attached to the ends of the bulb and sealed thereto. This cleaning is accomplished in any one of a number of ways, for exam ple, by brushing the phosphor off the ends of the bulbs.

Steps

100 and 102 can be carried out for a number of bulbs either sequentially or in a batch operation. The bulbs with the clean ends are then processed sequentially into a baking oven 104 to bake out the phosphor binders.

In step I06, the bulbs are subjected to a reduced pressure environment, of less than atmospheric pressure. This is accomplished, for example, by a reduced pressure chamber with an air lock at the input end. Both ends of the bulb being processed are completely open and the reduced pressure is applied to both ends of the bulb simultaneously. This speeds up the process of exhausting as compared with a conventional process in which stems with tubulations with more restricted areas are used. Further, any impurities within the bulb are removed from both ends which results in a faster impurity removal and prevents any impurities from travelling the complete length of the bulb, as is done in lamps with one tubulation or two tubulations, where the stem or stems are attached prior to the exhaust step and exhausting is accomplished only through one end.

In step 108, the bulbs at reduced pressure from step 106 are flushed with an inert gas such as argon or combination of argon-neon or argon-nitrogen, initially at the same pressure as in step 106, which is less than at mospheric pressure. In step 108, the pressure of the flushing gas is further reduced until the normal operating pressure of the finished lamp, for example, 3mm, is reached. If desired, this can be carried out in a two step, two-chamber process, rather than in a single chamber in one step. The flushing gas is left in the envelope to provide the operating fill gas for the lamp. If desired, step 106 can be carried out with one inert gas and the fill gas introduced separately in step 108.

With the envelope at the normal operating pressure and with its fill gas, mercury is added to the lamp as shown in step 110. The mercury can be added in any of a number of ways. For example, a small ampule of mercury can be dosed directly into an open end of the lamp. As another alternative, a mercury giver" in the form of a mercury compound or amalgam can be introduced into the lamp after step 108. Such mercury givers then require that the envelope be heated to break down the compound or amalgam. As another alternative, the fill gas which is introduced into the lamp in step 108 can be laden with mercury. If the pressure is reduced down far enough, for example to about 6 microns, the mercury will vaporize to produce the required amount of free mercury. All of these various arrangements for introducing mercury into the lamp are incorporated in step 110.'

Considering now the manner in which the end caps for the lamp are processed, two simultaneous process chains running along the drawing horizontally, are shown. This indicates an end cap for each end of the lamp bulb. The feeding of the end caps is preferably also sequential, in step with the processing of the bulbs. The assembled end caps, for example of the type of FIG. 2, or preferably de-gassed in a separate operation prior to being placed into the lamp process stream. The de-gassed caps are first subjected to a reduced pressure environment in step 120 of less than normal atmospheric pressure. This can be accomplished in a chamber with an air lock input. The end caps are then flushed with an inert gas, such as nitrogen or argon, and the pressure is further reduced. This can be accomplished in another chamber.

The cathodes of the end caps are then activated in step 124 by the application of a suitable electric current through the cathodes at a point external, or remote, from the lamp envelope. This boils off the impurities from the cathode. The impurities from the cathodes cannot in any way cantaminate the lamp at any subsequent stage of process since they are removed before the caps are applied to the envelope. This, of

course, is a decided advantage. During and after activation the cathodes are also preferably flushed with an inert gas, at a further reduced pressure from that of

steps

120 and 122.

After activation and flushing of the impurities, the end caps are subjected in step 126 to an atmosphere of the same inert gas used as the lamp fill gas. The pressure of the inert gas is further adjusted in step 128 to approximate that of the fill gas operating pressure, which is the same pressure as in step 108. Step 128 for the end caps serves as a buffer between the end cap processing and the bulb processing.

The end caps are assembled to the lamp bulbs in step 112. As indicated previously, the bulbs coming out of step 108 already are at the proper operating pressure, have the desired fill gas and have already been dosed with mercury. Similarly, the end caps from step 128 have been degassed activated, flushed, and are in an environment at the same pressure of the same fill gas as in the bulbs.

In step 112, an end cap is attached to each end of the lamp bulb, and fastened to it by a suitable sealing technique, such as described previously with respect to FIG. 2 and as is described subsequently with respect to FIG. 3. Since the contact pins are already attached to the end caps, a lamp which exits from step 112 is a complete fluorescent lamp, and the electrode structure has already been activated in step 124.

To complete the processing, the pressure of the chamber environment is increased in step 114 closer to atmospheric pressure, to act as a buffer to the air. The lamps are then subjected to an air pressure environment which is somewhat below that of atmospheric pressure in step 116, and finally to air at atmospheric pressure in step 118. In this step, they can be processed in the normal manner for shipping.

FIGS. 3 and 3A show another embodiment of end cap and lamp according to the present invention. The end cap uses a circular glass button of a glass compatible for sealing with that of a fluorescent lamp tube 12. The latter can be, for example, of lime glass. Thus, the button 10 also can be of lime glass or other material which is compatible for sealing to the fluorescent tube. Button 10 has an outer diameter which is greater than the outer diameter of the lamp bulb 12.

The glass button 10, which is to be sealed to each end of the tube 12, has an annular groove 14 which is tapered from the top down, as shown. The taper is such that the width of the bottom wall 15 of the annular groove is approximately equal to the thickness of the envelope 12 to which the electrode structure is to be attached. The wider portion at the top of the groove 14 is for the purpose of permitting an amount of a glass solder material, such as glass frit, to be placed therein to seal the end of the bulb 12 to the end cap.

A pair of cathode mounting members or leads, 18 and 19, of electrically conductive material, are held in circular depressions 20 formed in the top surface of the button by a suitable material such as solder glass frit 21. The leads can be of any conventional material. It has been found that an alloy such as Sylvania No.4, manufactured and sold by the Sylvania Electronics Division of General Electric and Telephone, operates satisfactorily. The cathode leads 18 and 19 terminate in respective electrically

conductive contact members

22 and 24 which can be of a solid rather than a hollow construc tion as is used with conventional bases which have metallic solder-type contacts. The portion between the leads l8 and 19 and the respective contacts is of slightly greater diameter than that of the

leads

18 and 19, to give the leads added strength. As should be apparent, the lead-contact pin structure can be made of a one piece solid construction.

To assemble the cathode-contact pin structure to the glass button 10, the ends of the

leads

18 and 19 are inserted through holes 25 in the button. The cathode mounting leads l8 and 19 are then sealed into the depressions 20 with the sealing material 21. This holds the entire structure to the cap. After this is done, a filament 26 is then mounted across the ends of the cathode mounting leads l8 and 1% in a conventional manner. The end cap is now ready for sealing to the end of a bulb 12 to form the complete lamp.

Lamps constructed in accordance with the process of FIG. 1, and having the end caps shown in FIGS. 2 and 3, have several advantages. First of all, since there are no stems used with flared ends for the end caps, the are stream has a longer arc length when the lamp is operated. In general, if the length of the arc stream in a conventional manufactured tube is 44 inches, about I /2 inches would be added in the lamps of the present invention, thereby giving an arc stream of approximately 45 /2 inches. By doing this, the lamp output in a conventional lamp can be increased by approximately lumens in a conventional 4-foot T 12 fluorescent lamp. The end losses of light are also considerably reduced since there is no light trapping behind a flare of a stem portion. Also, if desired, the inner surface of the end cap can be made light-reflective to further increase the light output.

The process of making lamps in accordance with the invention is simplified from conventional processes since three major areas of the latter are eliminated. These are: the conventional sealing of the stem to the lamp; exhausting of the tube through the tubulation of the stern; and basing of the contact members to the stems after the interior of the lamp has been processed. This speeds up the processing. Further, since the tubes are flushed and filled with gas through two full open ends, there is less tendency to blow phosphor off the tube wall as happens when gas is introduced and exhausted through a small tubulation. The free flow of gas through the two open ends of the bulb also speed up the processing.

As an another advantage. since the electrodes are pre-treated prior to fastening them into the envelope, there is less chance for sputtering of electrode material into the tube. in addition, the electrode structures are considerably simpler; that is. they are tiplcss, flareless and stemless, meaning that they are less subject to breaking.

The end caps of FIGS. 2 and 3 of the present invention have, in themselves, several advantages. As indicated before, the contact pins of the end caps are slotted and then they can be stamped or pressed together with the cathode leads as a one-piece unit, rather than providing lead wires through a flared stem and using a conventional base which is later connected to the leads which come out of the standard stem. As should be apparent, this is considerably different from and more economical than prior art electrode end cap structures. If desired, the inner surface of the end caps of FIGS. 2 and 3 also can be coated with a heat (infra-red) reflect ing material. This will keep the ends of the lamp cooler.

While a glassto-glass seal has been shown for the end cap to the bulb in the form of glass frit, other seal material can be used. For example, suitable plastics such as polyamide resins, indium-tin solders, etc., can be used.

The end caps can also be made of materials other than glass; for example, suitable plastic or ceramic materials. Suitable plastic materials which can be used are teflon and viton. End caps of these materials can be snapped over or screwed onto the ends of the envelope and coated with a suitable sealant. The plastic or other I material used for the end caps must be resistant to the metals used in the operating lamp, and also must be able to resist ion bombardment. Metal end caps are not as advantageous as caps made of an insulating material, since. if metal is used, some other insulating material has to be used to insulate the contact pins from the remainder of the metal end cap.

FIG. 4 shows a flow diagram for a process for manufacture of fluorescent lamps in accordance with another embodiment of the invention in which different types of end caps and electrode structures are used. Here again the process is a sequential one in which the bulbs and the end caps or electrode structures are fed sequentially to an assembly point where they are assembled at a predetermined time in the processing cycle to form the completed fluorescent lamps.

Before describing the process of FIG. 4, reference is made to FIG. 5 which shows one form of end cap structure which can be used with this process. The end cap of FIG. 5 is similar in some respects to that shown in FIG. 3. Therefore, the same parts are given the same reference numerals and are not further described. Here, in FIG. 5, a hold 70 is formed in the glass button and a tube of infra-red sealing material 74 is fastened within the hole to seal it by any suitable material, such as a glass solder material 76, on the inner surface of the end cap. The tube 74 is made of an infra-red type glass, which absorbs infra-red energy and melts in response to receiving a sufficient quantity of infra-red energy. It need extend only a very short distance into the envelope. The electrical contact pin and cathode structure is the same as for the end cap of FIG. 3.

Referring again to FIG. 4, the first step in the manufacture of the lamps is shown by block 210 which is the coating of the bulbs with any desired phosphor mix in a conventional manner and the cleaning of the bulb ends takes place. The coated bulbs are then lehred, by running them through any of the necessary ovens so that the phosphor will completely adhere to the inner surface of the bulbs.

Two blocks 214 are shown, one on each side of the vertical flow path in FIG. 4 to illustrate that one end cap is supplied for assembly to each end of a bulb in step 212. In step 212, the end caps of the type shown in FIG. 5, or of some other suitable type, are sealed into the ends of the bulb at atmospheric pressure. This is accomplished, for example, by using glass frit to solder an end cap to each end of a bulb.

The bulbs with the end caps sealed in are next conducted to a vacuum environment, such as a chamber with a suitable air lock input. In this step 216, they are exhausted through the tubulations 74 at both ends of the lamp simultaneously. The pressure used during the exhaust step is approximately in the order of one micron and the temperature is at about 40()500C. The bulb is baked in this step at this temperature for an amount of time sufficient to bake out all impurities. It should be understood that since both ends of the bulb are open through the tubulations 74 at the time the vacuum is being applied, the exhaust of all the impurities within the bulb occurs through both ends of the bulb rather than through one end as in a conventional exhaust process. Thus, there is no problem of entrapping impurities within the bulb or causing the impurities to travel the complete length of the bulb.

The bulbs pass out of the vacuum in step 216 and are next flushed in step 218 with an inert gas. The pressure of the inert gas in step 218 is substantially atmospheric pressure. The gas used in step 218 is to eventually be the fill gas. If desired, a buffer step of inert gas, such as argon, at a suitable pressure, such as for example somewhere between atmospheric pressure and lamp operating pressure, can be used between

steps

216 and 218.

In step 220 the electrodes are electrically activated to give off any decomposition products, which are impurities, that may be present. At the same time the activation is taking place, the lamp is also subjected to a pumping down operation in an argon, or other gas fill mixture, environment where the gas is pumped down to the desired fill pressure, for example, about 3 millimeters. This pumping down is effected through the two tubes 74. While the cathode activation and pumping are shown as two separate steps, it should be understood that they can be carried out at the same time the lamp is being exhausted simultaneously with the activation.

The decomposition products produced by the cathode activation are exhausted through the tubulations of the end caps of the lamp. As indicated before, these decomposition products also simultaneously pass out through both ends of the lamp due to the respective tubulations rather than passing out through only one end of the lamp where they might have a better opportunity to contaminate other portions of the lamp.

The pumped down lamps, which have approximately the fill gas pressure needed for operation and with the activated electrodes, are then dosed in step 224 of the process with the correct amount of mercury. The mercury can be added through the tubulation 74 of either end cap of the lamp.

After the mercury has been added, in step 226 infrared energy is focused upon the tips of the tubulations 74 of both end caps. Since the tubulations 74 are made of infra-red energy responsive glass, the infra-red energy melts the glass and seals the tubulations. At this time, the internal processing of the lamp is completed.

The lamp is then conducted to the atmospheric pressure in step 228. Since the end caps have the contact pins attached directly to them, there is no need to apply bases to the lamp.

Lamps processed in the manner of FIG. 4 with the end caps of FIG. 5, have many of the advantages of the lamps made with the end caps of FIGS. 2 and 3 according to the process of FIG. 1. For example, the end caps are attached directly to the lamp tube and no bases or stems are needed. However, the cathodes are activated while sealed into the lamp envelope instead of being activated external to the tube.

The process of FIG. 4 also can be used with an electrode structure of the more conventional type including a stern and base. An electrode structure of this type is shown in FIG. 6 which is conventional except that the tubulation is made of infra-red energy responsive glass such as is used for the tubulation 74 of the end cap of FIG. 5.

The electrode structure 80 of FIG. 6 includes the usual stem 81 with a flared lower end 82 which is to be sealed to the inner surface of an end of the lamp bulb. A tubulation 84 is located within the stem. The tubulation has a hole 86 at the upper end of the stem 81 and a tip end 88. A cathode shown in the form of a coiled filament-cathode 90 is mounted to the stern by

leads

91 and 92. The leads 91 and 92 are sealed in the stern and extend through the bottom end of the stem for connection to the contact members of a base which is to be mounted to the end of the tube.

The electrode structure 80 of FIG. 6 is used in the process of FIG. 4 in the same manner as the end cap of FIG. 5. The lamp is processed as previously described with the exception of step 212 where the stems are sealed into each end of the tube instead of sealing the end caps to the tube. Here, infra-red energy is focussed in step 226 to seal the tips 88 of the two tubulations on the lamp. in addition, a step 230 is added to the process where conventional bases are supplied in step 232, one to each end of the lamp. A base is fastened to each end of the tube over the tip end 88 of each tubulation. The leads 91 and 92 are electrically connected to the contact pins on the base, the contact pins being used to connect the lamp to a fixture. As should be apparent, in this process also the lamp tube is exhausted through both ends simultaneously to reduce the contaminants in the lamp.

What is claimed is:

l. A fluorescent lamp comprising a tube open at each end thereof and having a phosphor on the inner wall thereof, an end cap sealed to each end of the tube, each end cap formed with a pair of walls defining a groove into which an end of the tube fits to seal said tube to the end cap, each said end cap being of insulating material, electrical terminal means for connection of the lamp to a fixture attached directly to a respective end cap, a cathode carried by each said end cap within said tube, and means for electrically connecting a respective cathode to said terminal means of each said end cap.

2. A fluorescent lamp as in claim 1 wherein a said end cap has a top and a bottom wall, a said electrical terminal being mounted directly on said bottom wall and a said cathode means located above said top wall.

3. A fluorescent lamp as in claim 1 wherein at least one said end cap has a tubulation attached thereto, said tubulation formed of a radiant energy sensitive material which melts upon application of a sufficient quantity of said energy.

4. A fluorescent lamp comprising a tube without stems having a phosphor on the inner wall thereof, a separate end cap of insulating material and without a stem sealed to each end of the tube to seal said tube, at least one of said end caps including a tubulation through which said tube can be exhausted, said tubulation being of a material which is sensitive to energy of a predetermined wavelength to melt and seal the tubulation upon application of a sufficient quantity of said energy, cathode means mounted on each said end cap, and means for electrically connecting each said cathode means to a source of current.

5. A fluorescent lamp as in claim 4 wherein said tubulation of energy sensitive material is sensitive to infrared energy.

6. A fluorescent lamp as in claim 4 wherein a said end cap includes a base and said means for electrically connecting said cathode means to a source of current comprises a pair of contact pins mounted to one side of said base and cathode mounting means extending from the side thereof opposite said contact pins, said contact pins being electrically connected to said cathode mounting members.

7. A fluorescent lamp as in claim 4 further comprising means on each end cap for accepting an end of the fluorescent lamp tube comprising means forming a groove in said end cap into which said tube end fits.

8. A fluorescent lamp as in claim 7 wherein said groove forming means includes a pair of side walls on said end cap which taper down to provide a wider opening at the top thereof to accept the end of the tube and a quantity of a sealant to hold the envelopeend to the base.

9. An end cap for a stemless fluorescent lamp comprising a base of insulating material, means forming a groove on said base into which an open end of a fluorescent lamp envelope is to fit and be sealed, and a pair of cathode mounting members fastened directly to said base and extending from one side thereof, and cathode means electrically connected between said cathode mounting members.

10. An end cap as in claim 9 further comprising a pair of contact pins mounted to said base and extending from the side thereof opposite said cathode mounting members, said contact pins being electrically connected to said cathode mounting members.

11. An end cap as in claim 10 wherein said contact pins are of solid material.

12. An end cap as in claim 10 wherein each said cathode mounting member and a said contact pin is formed as a one-piece unit.

13. An end cap as in claim 12 wherein the cathode mounting end of each contact pin is provided with an opening into which an end of the cathode means fits, the said end of each said pin being crimped to provide the electrical contact between the mounting member and the cathode means.

14. An end cap as in claim 9 wherein said groove forming means includes a pair of spaced upstanding walls, the inner surface of said outer wall having an inwardly curved inner surface to accept a correspondingly curved end of a lamp envelope.

15. An end cap as in claim 9 further comprising a tubulation attached to said base and sealed thereto to provide communication from one side of the base to the other.

16. An end cap as in claim 15 wherein said tubulation is formed of an infra-red energy sensitive material so as to melt in response to receiving a sufficient quantity of said energy.

17. An end cap as in claim 9 in which said cathode mounting members are attached directly on said base.

18. An end cap as in claim 9 wherein said groove forming means includes a pair of side walls in said base which taper down to provide a wider opening at the top thereof to accept the end of the envelope and a quantity of a sealant to hold the envelope end to the base.

Claims

1. A fluorescent lamp comprising a tube open at each end thereof and having a phosphor on the inner wall thereof, an end cap sealed to each end of the tube, each end cap formed with a pair of walls defining a groove into which an end of the tube fits to seal said tube to the end cap, each said end cap being of insulating material, electrical terminal means for connection of the lamp to a fixture attached directly to a respective end cap, a cathode carried by each said end cap within said tube, and means for electrically connecting a respective cathode to said terminal means of each said end cap.

5. A fluorescent lamp as in claim 4 wherein said tubulation of energy sensitive material is sensitive to infra-red energy.

8. A fluorescent lamp as in claim 7 wherein said groove forming means includes a pair of side walls on said end cap which taper down to provide a wider opening at the top thereof to accept the end of the tube and a quantity of a sealant to hold the envelope end to the base.

11. An end cap as in claim 10 wherein said contact pins are of solid material.