US2391572A

US2391572A - Method for producing electronic devices

Info

Publication number: US2391572A
Application number: US519666A
Authority: US
Inventors: Herzog Carl
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-01-25
Filing date: 1944-01-25
Publication date: 1945-12-25
Anticipated expiration: 1962-12-25
Also published as: GB605329A

Description

Dec. 25, 194 5. c. HERZOG 2,391,572

METHOD FOR PRODUCING ELECTRONIC DEVICES Filed Jan. 25, 1944 5 Sheets-Sheet l (BWM p.

Dec. 25, 1945. c. HERZOG METHOD FOR PRODUCING ELECTRONIC DEVICES Filed Jan. 25 1944 5 Sheets-Sheet 3 Dec. 25, 1945. c. HERZOG METHOD FOR PRODUCING ELECTRONIC DEVICES Filed Jan. 25, 1944 5 Sheets-Sheet 4 Dec. 25, 1945. c. H ERZOG METHOD FOR PRODUCING ELECTRONIC DEVICES Filed. Jan. 25, 1944 5 Sheets-Sheet '5 cathodes sealed-in the same and Patented Dec. 25, 1945 METHOD ron PROD DEVI

UCING ELECTRONIC cns 081'] nemgneuevme, N. J. Application January 25, 1944, Serial No. 519,666

(Cl. 316-24) 1 I 11 Claims.

My invention relates to a method of and apparatus for producing electronic devices, such as gaseous discharge tubes including cold cathode fluorescent lamps, hotcathode fluorescent lamps and neon lamps, and radio tubes or the like, and

to such devices.

An important object of the invention is to provide a method whereby the cathodes may have parts thereof sealed-in the ends 01' the tube,"vvithout employing the usual glass caps having the which caps are fused to the ends of the tube.

A further object of the invention is to produce a method of the above mentioned character which will materially reduce the time heretofore required in producing electronic devices.

A further object of the invention is to provide a method of the above mentioned character, which .Will simplify and expedite the evacuation, sealing-in of the tube and seeming the cathodes in place.

A further object o! the invention is to provide a method of the above mentioned character, which will properly center thecathode with respect to the tube.

A further object of the invention is to provide a cathode unit which may be readily sealed-in the tube and have a part serving as a contact, thus eliminating the use of a separate contact cap.

A further object of the invention is to provide a method of the above mentioned character which combines the exhausting and sealing-in operations, in the continuous production of electronic devices.

A further object of the invention is to provide a cathode unit which will simplify the sealing-in of the tube and will dispense with the use of.

additional centering means for the cathode.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings, forming a part of this application, and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a central vertical section through v the tube of a cold cathode fluorescent lamp, parts broken away, and the cathodes arranged near the ends of the tube,

I Figure 2 is a similar view, showing the cathode introduced into one end of the tube, and the tube heated, prior .to sealing-in,

Figure .2 is a similar view, showing the sealing-in of one end of the tube,

Figure 3 is a central longitudinal section through one end of the tube, showing the cathode within the tube, the lead-in wire provided with a glass bead and the tube heated, for eflecting a modified method of sealing-in,

Figure 4 is a similar view, showing the tube and bead fused and formed to provide a closed end,

Figure 5 is a view similar to Figure 3, showing a further modified form of glass bead,

Figure 6 is a similar view, showing the tube and bead heated, formed, and fused together, for

sealing-in,

jaws closed,

Figure 7 is a central vertical section through the opposite end of the glass tube with respect to Figure 3, showing the cathode in place and the tube formed or necked, after the insertion of the cathode, but before evacuation of the tube,

Figure 8 is a'similar view, showing the tube and bead heated, fused and formed, for sealing-in,

Figure 9 is a central vertical section through the apparatus for evacuating the tube and sealing-in the opposite end of the tube, the forming Figure 9 is a similar view, with the forming jaws open, after the completion of the sealing-in operation, a

Fi e 10 is a horizontal section taken on line iii-40 of Figure 9', 1

Figure 11 is a perspective view of a cathode showing the centering device carried thereby,

Figure 12 is a front end elevation of the cathode and the centering device, v

Figure 13 is a central vertical longtitudinal section through the same,

Figure 14 is an exploded perspective view of the centering device,

Figure 15 is a central vertical longitudinal section through a cathode and a modified form of centering device,

Figure 16 is an end elevation of the same,

Figure 17 is a perspective ,view of the cathode and the centering device,

Figure 1815 a central vertical longitudinal section through a complete lamp made in accordance with the first method,

Figure 19 is a similar view of a modified compiete lamp, made in accordance with a modifled method using glass beads,

Figure 20 is a central longitudinal section {through one end or the tube, illustrating the step of sealing-in a modified form or cathode unit.

Figure 20 is a diagrammatic view further iilustrating the method or sealing-in the cathodes I shown in Figure 20,

Figure 21 is a central vertical longitudinal section through a complete lamp including the modified cathode units shown in Figure 20,

Fi ure 22 is a transverse section taken on line 2 222 of Figure 21, 4

Figure23 is a central vertical'longitudinal section through acomplete lamp embodying a further modified form of cathode units, and,

Figure 24 is a transverse section taken on line 24-24 of Figure 23.

In the. drawings, wherein for the purpose of illustration is shown a preferred embodiment of tube, constituting the envelope of the cold cathode fluorescent lamp. This tube may be of any suitable diameter and length. These tubes are frequently a half inch in diameter and eight feet my invention, the numeral 20 designates a glass 5 long, although the dimensions may be widely l0 varied. The inner surface of the glass tube 20 is covered or coated with fluorescent material or powder 2| in any well known or preferred manner. The ends of the inner face of the tube 20 are cleaned of the fluorescent coating. Providing clean or

uncoated end zones

22 and 23, extending inwardly to lines' 24. The tube with the

end zones

22 and 23 is about three inches longer than the glass tube which would be used in the ordinary method of producing a cold cathode fiuo- 20 rescent lamp, of a desired length. In the old method, previously formed glass caps or ends are fused to the ends of the tube, while in my present method these glass caps are eliminated,

and the ends'of the glass tube are heated and 25 are introduced into the ends of the tube 20.

Each electrode is secured to a single lead-in wire 25, which forms a conducting part for the electrode. i

As more clearly shown in Figures 11 to 14, in-

clusive, the electrode 25 is provided with an outwardly projecting bead or rib 21. A centering device is mounted upon the cathode 25 in advance of the rib 21. This centering device includes resilient mica strips 28, Each strip has a pair of transverse slots 29. These strips are arranged in a pair of opposed groups, Figure 14, so that the strips 28 of one group interfit and interlock with the strips 28 in the other group, the slots 29 of one strip receiving the material of the companion strip 28-01 the other group. as is obvious. These assembled mica strips produce an annular group which surrounds the cathode 25 in advance of the rib 21. The annular group includes a hub portion and radial portions extending beyond the hub portion. Tris annular centering device has a slightly larger diameter than the interior of the tube 20 so that it is placed under compression when introduced into the tube 20 and will center the electrode within the tube and retain the same centered.

In Fi ures 15 to 1'7, inclusive. I have shown a modified form of centering device. In this form of the invention, the electrode 25 has metal strips so welded to the same, having outwardly projecting free ends 3!. These free ends are inserted through slots 32, formed in mica strips 33, and the free ends 3| are then bent downwardly upon the mica strips. The mica strips are thereby attached to the cathode 25. The mica strips are oversized for the tube 20. Figure 16, and are therefore placed under tension or compression when the cathode 25 is inserted into the end of the tube 20. and serve to center the cathode with respect to the tube and retain the same so centered.

At the starting of the method, both ends of the tube 20 are open and the electrode 25, which may be equipped with the centering devices shown in Figures 11 to 13, inclusive, is introduced into the end or the tube 20 at the zone 22. The

annular group of mica strips 28 will now hold the cathode centered within the tube 20, while its lead-in wire 26 will project through and beyond the open end of the tube 20. At this time, the tube 20 may be horizontally arranged, and the lead-in wire 26 may be held in a metallic clamp 34 including a rigid jaw 35 and a meeting resilient jaw 36. This clamp is employed to hold the lead-in wire 26 in position,

While the electrode 25 is thus held in place within the tube 20, at the zone 22, flame or heat is applied to the-end of the tube at the zone 22 from burners 31, which serve to plasticize the glass, and the molten glass is acted upon by the

jaws

38 and 39, which form the same into a closed end 40. The lead-in wire 26 is embedded centrally within the end 40, and has a vacuum tight joint therewith, as shown. The zone 22 is left clean and uncoated with the fluorescent powder so that when it is heated and plasticized it ma be readily fused and formed into the end 42.

In some instances, where the tube 20 is of larger diameter, I have found it advantageous to apply a glass bead 4| to the lead-in wire 26, Figure 3. This glass bead may be formed from a section of a glass tube and applied to the lead-in wire 26 and may be fused thereto, to provide a vacuum-tight joint. When heat is applied to the end of the tube 20, adjacent to the glass bead All, the tube and head are plasticized, and the tube and bead are fused together and may be formed, in the manner illustrated in Figure 4, whereby a closed end 42 is produced. It is obvious that a vacuum-tight joint is effected between the closed end of the tube and the lead-in wire 26. I

In Figure 5, I have shown a glass bead 43 of a difierent construction, the same having a greater diameter. The tube 20 is heated at 44 and the head 23 is heated sufilciently so that its outer portion is plasticized and will fuse with the tube, when the plasticized tube is formed by the

jaws

88 and 39, Figure 6, forming a closed end. In this form of the invention, the bead is previously fused to the lead-in wire 26 to form a vacuumtight joint.

After the end of the tube 20 adjacent to the zone 22, has been sealed in and closed, as explained, the tube is vertically arranged 'with its i5, which is vertically arranged and has a main cylindrical chamber 46, leading into an upper reduced cylindrical chambe 41, in spaced concentric relation thereto. There is a water Jacket 418 which surrounds the chamber 41, having an inlet 49 and an outlet 50. The head has a mercury supply port 5i leading into the chamber 41. The upper end of th port 41 leads into a cylindrical chambe 52, which leadsto a hopper 53. A rotary valve 54 is mounted within the chamber 52, and has recesses 55 for conveying a measured amount of mercury from the hopper 53 into the port 5|. The head also has a port 56, which leads into a T-coupling or two-way valve 51, having a branch 58 which leads to a source of vacuum, and a branch 59 which leads to a source of inert gas. 50 designates a pivoted valve element to-altemately connect branch 58 with port 56 and then break this connection and connect branch 59 with port '56.

The chamber 46 receives an annular packing member 5|, which may be formed of rubber or the like and is adapted to be compressed by a tion of the tube, in whole Care should be taken that the blades sever the lead-in wires.

wire 26 without a glass bead thereon, in accordance with the method indicated in Figures 1 and shank 68 having a shoulder 69. The shank is inserted through an electrical insulating sleeve 16, held within an opening II in the head. The shank is held in place by a nut 12, having screwthreaded engagement therewith. The nut is insulated from the head 45, at 13, and the shoulder 68 so insulated at 14.

. 4 is employed, at one end of the tube 26,'it would- The companion electrode 25 is vertically airanged and has its lead-in wire 26 held between the

laws

66 and 61, and depends below the head 45. The tube 28 is vertically arranged, with its open end uppermost, as stated, and the open end of the tube is now inserted into the chamber 46 and into the annular sealing element 6|. Prior to this insertion, th cathode 25 passes into the open end of the tube 20, adjacent to the zone 23, and is retained in spaced concentric relation to the tube by the centralizing device, as shown in Figures 11 to 13, inclusive. The nut-cap 63 is now screwed up to place the element 6| under compression to form a vacuum-tight joint with the tube 20. The open end of the tube is now in free communication with the chamber 41.

The valve element 60 which was previously in the neutral position, Figure 9, is now turned to place the port 56 in communication with the port 58, whereby the interior of the tube is placed in communication with the source of vacuum and the tube suitably evacuated. During the evacuating oi the tube 20, the electrodes are connected with the opposite poles of the source of current, through the terminals 80 and 8!. This is done to heat the electrodes and drive oil undesirable gases and impurities. After the proper vacuum is attained, the valve element is turned to connect covering port 58, to

supply a very small amount of inert gas, such as argon 0r neon, intothe tube 28. The amount .of inert gas thus supplied is small and does not perceptibly change the degree of vacuum in the tube 28. The valve element 60 is now moved to the neutral position to cover port 56, Figure 9. After this, the valve 54 is moved to supply the measured amount of mercury to the tube 20, which drops to the bottom of the tube. This measured amount of mercury is ordinarily a ball of about or slightly less than one thirty-second of an inch in diameter.

After this operation, heat is applied from the burners 15 to the tube 20 at about the point 16, to plasticize the tube.

formed by the jaws 11, into the closed end 18,

p with the lead-in wire 26 embedded thereinfto form a vacuum-tight Joint. After this operation, the end 18 may be severed from the upper porciprocatory blades end should remain attached to the tube, it may be readily broken therefrom when the parts cool. 18 do not During the formation of the closed end 18; the vacuum in the tube aids the jaws 11 in forming the end 18. After the closed end 18 has been formed, the jaws 11 and blades 19 are moved to the outer position, whereby the end 18 is released and the lead-in wire 26 is freed from the clamp 65, by drawing the same downwardly from the clamp.

In forming the end 18, I may use the lead-in port 56 with port 59, while and this tube is then or in part, by the 're-. 19. If asmall portion of the 2. Where the glass bead shown in Figures 3 and also be employed at the other end of the tube. When this is done, after the cathode is inserted into the tube, Figure 7, the tube may be heated and necked inwardly at 82, and again allowed to set or harden, after which thetubeis evacuated and subsequently filled with the inert gas, by insertion into the head 45, as explained. The

mercury is also introduced in the tube, as stated. After this operation, the necked portion 80 would be heated and plasticized and subjected to the action of the jaws '19, to form the closed end-18', having the lead-in wire 26 embedded therein, Figure 8. The glass bead 4| aids in forming the ends 78', where the tubeis of larger diameter.

. When the bead 4| is small, Figure 8, the sealing-in --beyond the tube 20.

may be aided by thejaws 71, but when a large bead'43 is used, Figure 6, the vacuum within the tube may be suilicient to effect the sealing-in operation and fuse the bead 43 to the tube, although this operation may be aided by the

jaws

38 and 39, Figure 6.

In Figure 18, I have shown a complete lamp made in accordance with the first method, Figures 2, 2 and 9. The closed ends 46 and 18 have metallic contact caps 82 mounted thereon, and secured thereto by cement 83. These metallic contact caps have openings for the passage of the lead-in wires 26,'which are electrically connected withthe caps by solder 84. The lead-in wires are ordinarily cut ofi upon the outer sides of the contact caps. I

These contact caps are also applied to the closed ends of the tubes 20 embodying the beads 4|, Figure 3, in the same manner as shown and described in connection with Figure 18.

In Figure 19, I have shown a completed lamp including ends embodying the large 'beads 43,

Figure 6. These beads form with the tube 20 closed ends and the metallic contact. caps- 82 are applied to these closed ends and secured thereto by the cement 83'. The lead-in wires 26 pass through the openingsin the contact caps and are secured thereto by the solder 84.

In Figure 21, I have shown a completed lamp embodying a further modification of the invention. In this form of the inventiomthe electrodes 25" are provided at their outer ends with enlarged radially portions retainers 85, carrying contact extensions 86, which project outwardly The radially enlarged portion 85 constitutes a conducting part for the tubular electrode 25. The tube 20 has its ends heatedgand plasticized, so that the enlarged portions 85 are sealed into the tube 20, forming a vacuum-tight joint. As shown in Figure 20, one cathode 25 is held by a socket 81, and inserted into the end of. the tube 20 at the zone 22. The

' tube 20 is then heated adjacent to the Z0ne 22,

to plasticize the same, and the plasticized end is formed by the

jaws

38 and 39, Figure 2, so that the tube 28 is fused to the enlarged portion 85 to form a vacuum-tightjoint. To close the opposite end of the tube 20 and fuse the other electrode 25' to the tube, a socket 81 is secured to the shank", Figures 9 and 20, in place of the clamp 65. The contact extension 86 is now inserted in this vertically'arranged socket '81, so that the electrode 25 is supported vertically and will be passed into the o posite end of the tube 20 when such end of the tube is'inserted into the sealing element 6|. The samesteps are practiced to provide a vacuum-tight joint.

evacuate the tube, feed in the inert gas and the mercury, after which the tube is heated at the zone 23, plasticized, and formed by the jaws 11, if necessary, so that the tube is fused to the enlarged portion 85 to form a vacuum-tight joint.

In Figure 23, I haveshown a completed lamp wherein-electrodes are press-fitted into contact extensions 88 of retainers 89. These retainers have a larger diameter than the electrodes 25 and have the tube 20 fused to the same, to If desired, the electrodes 25 may be welded to the contact extensions 88, at the point 98. The electrode unit 25, Figure 21, and the retainer 88 are made of a special commercial chrome-iron alloy which has the same expansion coeflicient as glass. The enlarged portion 85 of the tubular electrode 25 forms a ring or band extending radially beyond the tubular electrode, and this ring or band is concentric with the tubular electrode. The outer end of the tubular electrode is imperforate and the contact extension 86 projects axially beyond the tubular electrode in an outward direction. The retainer 89 also provides a ring or band which is concentric with the tubular electrode 25 and extends radially beyond same, and a contact extension 88 extends axially beyond the retainer in an outward direction. The tube 20 is severed adjacent to the outer ends of the enlarged portions I 8 or retainers 89, so that the

contact extensions

86 and 88 project outwardly beyond the ends of the glass tube.

The lamp shown in Figure 23 is assembled in accordance with the method of producing the lamp shown in Figure- 21. The advantages of the lamps shown in Figures 21 and 23, are that they eliminate the use of the mica centering devices, and the use of the separate contact caps 82. The electrode units 25 Figure 21, are rigid, and the enlarged portions 85 retain them centered in the tube 20. The electrodes 25 are retained centered in the tube 20, Figure 23, by the rigid retainers 89. By eliminating the separate contact caps 82, no additional work is necessary after the lamp is sealed-in, Figures 21 and 23. The rigid cathode units, Figure 21, and retainers 89, Figure 23, simplify the sealing-in method, as compared with the use of the bead 43, Figure 6. This glass bead 43 may become soft or plastic during the sealing-in operation, and to prevent this, an accurate control of the applied heat is necessary, so that the sealed-in end will not collapse, due to the vacuum, within the tube. Further, a layer of glass may be bonded or fused to the periphery of the part 85 or the retainer 88, prior to the introduction of the electrode into the tube, whereby two glass surfaces may be fused together.

The lamps shown in Figures 21 and 23, have in common with the lamp shown in Figure 18, the tube 20 with the fluorescent coating 2|, and the cathodes in the ends of the tube. Each lamp is evacuated and contains a suitable amount of inert gas and a suitable amount of mercury. The method employed to seal-in the-ends oi the lamps shown in Figures 21 and 23, is substantially identical with the method used in producing the lamp of Figure 18.

It is to be understood that the forms of my invention herewith shown and described are to be taken as preferred embodiments of, samaand that various changes in the shape, size, and arrangement of parts, may be resorted to, without departing from the spirit of the invention, or

the scope of the su-bioined claims, and that changes may be made in the order of the steps of the method, without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. In a method of producing an electronic device, the steps of supporting a tube having its opposite first and second ends open, introducing into the first open end of the tube an electrode having a radially enlarged part, heating such first open end and fusing the same to the radially enlarged part, introducing into the second open end of the tube a companion electrode having a radially enlarged part, evacuating the tube through the second open end, and heating the second open end and fusing the same to the radially enlarged part of the companion cathode.

2. The method of producing a cold cathode fluorescent lamp, comprising supporting a glass tube having its inner surface coated with a fluorescent material and its ends open, arranging a tubular electrode within the glass tube near one end thereof, heating such end of the glass tube and forming the same into a closed end portion and embedding a part of the tubular electrode in such end portion, arranging a companion tubular electrode in the glass tube near its opposite end, arranging the glass tube substantially vertical with its opposite open end uppermost, applying a vacuum to the upper open end of the tube, subjecting the electrodes to the action of an electric current during the evacuation of the tube, introducing into the tube through itsupper open end an inert gas, introducing into the tube through its upper open end mercury, heating the glass tube between its upper open ends and the companion electrode and forming the same into a closed end portion and embedding a part of the tubular companion electrode in such end portion, and separating the last named end portion from the upper open end of the tube.

3. The method of producing a cold cathode fluorescent lamp, comprising coating the interior a of a glass tube having opposite first and second open end portions with a fluorescent material and providing uncoated first and second end zones, arranging a tubular electrode having a conducting part within the first end portion and arranging the conducting part within the first uncoated end zone, heating the first uncoated end zone and fusing the same to the conducting part for forming therewith a vacuum tight joint, arranging a second tubular electrode having a conducting part within the second end portion and arranging the second conducting part within the second uncoated end zone, forming a passage within the glass tube exteriorly of. the second tubular electrode, connecting the second end portion with a source of vacuum and thereby evacuating the glass.tube through the passage exteriorly of the second tubular electrode, and heating the second uncoated end zone and fusing the same to the second conducting part of the second vacuum to evacuate the tube by suction action 1 the tubular electrodes radially spaced from the tube.

5. The method of producing a cold cathode fluorescent lamp, comprising coating the interior of a glass tube having opposite first and second open end portions with a fluorescent material and providing uncoated first and second end zones, arranging a tubular electrode having a conducting part within the first end portion and arranging the conducting part within the first uncoated end zone, heating the first uncoated end zone and fusing the same to the conducting part and forming therewith a vacuum tight joint, arranging a second tubular electrode having a conducting part within the second end portion and arranging the second conducting part within the second uncoated end zone and forming a passage within the tube exteriorly of the second tubular electrode and its conducting part, arranging the glass tube substantially vertically with its second end portion uppermost, connecting the upper second end portion with a source of vacuum to evacuate the glass tube through the passage exteriorly of the second tubular electrode,and conducting part, subjecting the electrodes to the action of an electric current during the evacuation of the tube to heat and purify the same, introducing an inert gas into the upper second end portion, introducing mercury into the upper second end portion, and heating the second end zone and fusing the same to the second conducting part for forming a vacuum tight connection.

6. The method of producing a cold cathode fluorescent lamp, comprising coating the interior of a glass tube having its opposite ends open with a fluorescent material and providing uncoated end zones, arranging the tube substantially vertically, arranging imperforate tubular electrodes having conducting parts within the opposite ends of the tube and arranging the conducting parts within th uncoated end zones, connecting one end of the-tube with a source of vacuum to evacuate the tube by suction action within the tube exteriorly of one tubular electrode, subjecting the electrodes to the action of an electric current during the evacuation of the tube for heating and purifying the electrodes, introducing an inert gas into the tube, introducing mercury into the upper portion of the tube, heating the uncoated end zones' and fusing the sameto the conducting parts and forming a vacuum tight connection therewith, and retaining the tubular electrodes radially spaced from the tube.

7. The method oi producing a cold cathode fluorescent lamp, co prising the steps of supporting a glass tube having one end open and an interior coating of fluorescent material, introducing into the open end of the glass tube a tubular electrode having its outer end impersupporting the tubular electrode within the glass tube for forming a passage within thetube exteriorly of the tubular electrode, connecting the open end of vthe glass tube with a source of vacuum to evacuatethe tube through the passage exteriorly of the tubular electrode, heating the all glass tube adjacent to the radially enlarged part and fusing the glass tube to such radially enlarged part for forming a closed end, the radially enlarged part retaining the tubular electrode 'spaced from the glass tube.

8. The method of producing a cold cathode fluorescent lamp, comprising the steps of supporting a glass tube having one end open and an interior coating of fluorescent material, introducing into the open end of the glass tube a tubular electrode having its outer end imperforate andprovided with a radially enlarged part and an axial contact element projecting outwardly, supporting the tubular electrode within the glass tube for forming a passage within the tube exteriorly of the tubular electrode and so arranging the tubular electrode that the open 32nd of the glass tube extends axially outwardly beyond the same, connecting the open end of the glass tube with a source of vacuum to evacuate the tube through the passage exteriorly of the tubular electrode, heating the glass tube adjacent to the radially enlarged part and fusing the glass tube to such radially enlarged part for forming a closed end, and severing the glass tube' adjacent to the radially enlarged part so that the contact element extends axially beyond the glass tube of the completed lamp, the radially enlarged part retaining the electrode spaced from the glass tube.

9. The method of producing a cold cathode fluorescent lamp, comprising supporting a glass tube having its opposite ends open and its inner surface coated with fluorescent material, introducing tubular electrodes having their outer ends imperforate and provided with radially enlarged parts into the opposite ends of the tube, connecting one end of the tube with a source of vacuum to evacuate the tube by suction action within the tube exteriorly of one tubular elec-- trode, heating the tube adjacent to the radially enlarged parts and fusing the same to such enlarged parts for forming closed ends, the tubular electrodes being retained radially spaced from the tube by the radially enlarged parts.

10. The method of making a cold cathode fluorescent lamp or the like, comprising the steps of supporting a glass tube having one and open and an interior coatingof fluorescent material, introducing into the open end of the glass tube a tubular electrode having a metal band extending radially beyond the tubular electrode and forming a passage between the metal band and.

the glass tube, connecting the open end of the glass tube with a source of vacuum, heating the glass tube adjacent to the metallic band and fusing the glass tube to such metallic band, the metallic band retaining the tubular electrode spaced from the glass tube.

11. The method of making a fluorescent lamp or the like, comprising the steps of supporting a glass tube having one end open and an interior coating of fluorescent material, introducing into forate and provided with a radially enlarged part. 1

the open end of the glass tube an electrode having a metal band connected therewith which extends radially beyond the electrode andforming a passage between the metal band and the glass tube, connecting the open end ofthe glass tube with a source of vacuum, and heating-the glass tube adjacent to the metal band and fusing the glass tube to such metal band, the metal band retaining the electrode spaced from the glass tube.

CARL HERZOG.