Document qwpLvEZLb2KnBm5QdEG019oG

United States Patent m Wardell, Jr. et al. [ii] 4,076,366 [45] Feb. 28, 1978 [54] HIGH VOLTAGE ELECTRON TUBE BASE WITH SEPARATE DIELECTRIC FILL-HOLE [75] Inventors: Myron Henry Wardell, Jr., Lititz; Bruce George Marks, Lancaster, both of Pa. [73] Assignee: RCA Corporation, New York, N.Y. [21] Appl. No.: 798,127 [22] Filed: May 18,1977 [51] Int.Cl.2..............................................H01R 13/46 [52] U.S. CL................................ 339/144 T; 313/318 [58] Field of Search.......... 339/143 R, 143 T, 144 R, 339/144 T, 145 T, 275 B; 313/318, 57,477, 482 [56] References Cited U.S. PATENT DOCUMENTS 3,278,886 4.040.707 4.040.708 10/1966 8/1977 8/1977 Blumemberg et al............. 339/145 T Pisano ................................. 339/143 T Neuber et al........................ 339/143 T Primary Examiner--Roy Lake Assistant Examiner--E. F. Desmond Attorney, Agent, or Firm--E. M. Whitacre; G. H. Bruestle [57] ABSTRACT The base comprises a tubular housing adapted to fit over the exhaust tubulation of an electron tube stem, and a wafer flange extending outwardly from the open end thereof. The flange is apertured to receive an array of conductors of the stem. A recess is provided in the wafer flange facing the stem and a passageway commu nicating therewith is provided through the base sepa rate from the housing cavity for the purpose of injecting a dielectric material into the recess around some of the stem conductors. The passageway may, e.g., be through the flange or in the housing wall. A shoulder is provided on the recessed face of the wafer flange to provide relief for random protuberances on the periphery of the stem to permit non-tilted mounting of the base on the stem. 9 Claims, 12 Drawing Figures U.S. Patent Feb. 28, 1978 Sheet 1 of 3 4,076,366 Fig. f. U.S. Patent Feb. 28, 1978 Sheet 2 of 3 4,076,366 Fig. 8. Fig.7. U.S. Patent Feb. 28, 1978 Sheet 3 of 3 4,076,366 Fig.lO. Fig. II. Fig. 12. 4,076,366 12 neck, it causes a drip or slight protuberance in the glass HIGH VOLTAGE ELECTRON TUBE BASE WITH to form at one point around the periphery of the stem. SEPARATE DIELECTRIC FILL-HOLE When prior art bases have been applied to stems having drips of this type, the base is caused to tilt relative to the This invention relates to electron tube bases and par 5 longitudinal axis of the tube. Such tilt, in addition to ticularly to those of the wafer type which include a being aesthetically undesirable, often creates problems body of dielectric material molded therein for the pur in inserting the base into its mating socket. Further pose of increasing the voltage breakdown between the more, the gap between the base and stem due to the lead-in conductors of the base. tilting frequency allows the dielectric material injected BACKGROUND OF THE INVENTION 10 into the base to flow therefrom leaving a deficiency of material to provide the desired dielectric body for high One type of electron gun recently proposed for color voltage breakdown insulation. picture tubes is described in U.S. Pat. No. 3,995,194, issued to Blacker et al. This gun includes an electrode to SUMMARY OF THE INVENTION which an operating voltage of approximately 12 kilo- 15 A wafer type electron tube base having an exhaust volts is applied. In the manufacture of tubes incorporat tubulation housing is provided with a dielectric receiv ing such guns, it is often desired to apply a "spot-knock ing recess in the wafer thereof. A passageway in the ing" voltage of approximately 30 kilovolts to this elec base communicating with the recess is provided as a trode in order to remove sharp points and particles fill-hole for the plastic dielectric material. The passage- therefrom which might otherwise later cause harmful 20 way is separate and apart from the cavity of the tubula arcing during tube operation. This spot-knocking volt tion housing cavity. age must be brought in through the base and stem of the tube, and severe voltage breakdown problems are en BRIEF DESCRIPTION OF THE DRAWINGS countered when conventional prior art bases are used. FIG. 1 is a side elevation view with parts broken U.S. Pat. No. 3,278,886 to Blumemberg et al discloses 25 away of the novel tube base disposed in mating relation a type of wafer base in which a housing is disposed over with a cathode ray tube, only the stem and adjacent the exhaust tubulation of an electron tube stem and the neck portion of which are shown. stem's lead-in are disposed through apertures in a wafer FIG. 2 is an enlarged bottom plane view of the tube flange extending from the housing. U.S. Pat. No. base of FIG. 1 taken along the line 2--2 thereof. 3,979,157 to Dimattio discloses a modification of this 30 FIG. 3 is an enlarged top plan view of the electron type of wafer base in which the lead-ins are disposed in tube base of FIG. 1 taken along the line 3--3 thereof. grooves in the housing wall of the base and lie against FIGS. 4, 5, 6 and 7 are sections taken through the the floor of the grooves. tube base of FIGS. 1,2 and 3 along the lines 4--4, 5--5, The Blumemberg et al base is especially designed for 6--6, and 7--7, respectively of FIG. 2. high voltage applications. To this end it incorporates a 35 FIGS. 8 and 9 are enlarged longitudinal section views tubular silo structure which surrounds one of the lead- of modifications of the base of FIGS. 1-7. ins to which high voltage is applied, and a recess in the FIGS. 10 and 11 are plan views similar to that of base into which a dielectric material is molded around FIG. 3 of modifications of the base of FIGS. 1-7. the lead-ins. Both of these features serve to increase FIG. 12 is a perspective view of another embodiment resistance against high voltage breakdown. 40 of the novel tube base. In mounting a base of the Blumemberg et al type to an electron tube stem, it has been the practice heretofore to simply insert a quantity of plastic dielectric material into DESCRIPTION OF PREFERRED EMBODIMENTS the recess of the base and then apply the base to the Referring to FIGS. 1-7, a glass neck portion 10 of a stem. Since the dielectric material is applied to the base 45 color picture tube is closed at one end with a glass stem while it is out of contact with the stem, the result is a 12 which includes an array of stiff conductors 14. The messy process. Alternatively, the plastic dielectric ma conductors 14 are sealed through the stem 12 and ex terial may be injected through the exhaust tubulation tend therefrom in a circular array parallel to each other. housing. When the latter is done, sufficient material The stem 12 also includes a closed off exhaust tubula must be injected to completely fill the housing in order 50 tion 16 disposed centrally within the circular array of that some of the dielectric material is forced into the conductors or leads 14. A base member 18 is attached to recess in the bottom of the base. The difficulty with this the end of the stem 12. procedure is that exhaust tubulations are not of uniform The base member 18 of the wafer type and comprises volume from tube to tube, and hence the amount of a cylindrical housing 20 having an opening 21 at one dielectric material which must be injected varies from 55 end and a wafer flange 22 which extends radially out tube to tube. This prevents the injection of a specific wardly therefrom. The cylindrical housing 20 is hollow amount of material and thus complicates the injection and fits loosely over the exhaust tubulation 16. The process. outer cylindrical surface of the housing 20 is provided Prior art bases such as the Blumemberg et al base with a series of longitudinal grooves 24 which extend experience another problem when they are used with 60 from the wafer flange 22 to the opposite distal end of neck-stem structures as conventionally fabricated in the the housing 20. The wafer flange 22 is provided with a color picture tube industry. In fabricating the neck-stem circular array of apertures 25 therethrough. The circu structure of a picture tube envelope, the neck is heated lar array of conductors 14 are disposed through the to soften the glass and fuse it to the stem. The heating is array of apertures 25 and lie one in each of the grooves continued until a short length of neck section extending 65 24. beyond the stem is completely severed from the remain The base 18 is also provided with a tubular chamber der of the neck and drops free therefrom. When this or silo 26 (FIGS. 2 and 6) disposed coextensively along short piece of neck section separates from the rest of the side the housing 20. The silo 26 is closed at one end by 4,076,366 34 the wafer flange 22 and is open at the opposite end. The the first section 32a where high voltage breakdown silo 26 receives therein one of the leads 14 which is insulation is more important. intended to have a high spot-knocking voltage applied In the embodiment of the base of FIGS. 1-7, the thereto. The silo 26 serves to provide a greatly in fill-hole 36 is shown in its simpliest form as a straight creased discharge path from the high voltage lead con 5 cylindrical bore. However, other forms of the fill-hole, tained therein to any one of the adjacent leads. wherein the passageway thereby provided may be bent, Also provided to increase voltage breakdown be may be provided as alternatives. For example, in FIG. 8 tween the leads is a radially extending fin 28 disposed a base 118 is provided with a fill-hole 136 which in between two adjacent leads 14. The fin 28, while not as cludes a first portion 142 communicating with a recess effective as the silo 26 is preventing high voltage break 10 132 in the wafer flange portion 122 of the base 118, and down, is nevertheless adequate for the lesser voltages to a second portion 144 which is offset toward the central be applied to the leads 14 on the opposite sides thereof. axis of the base 118 and is somewhat enlarged relative to The stem-contacting face 30 of the wafer flange 22 is the first portion 142. The offset is preferred so that provided with a recess 32. The depth of the recess 32 is when a dielectric injection nozzel is pressed against the not critical. It need be only deep enough to allow a thin 15 opening in the fill-hole 136, the force applied to the base layer of dielectric material molded therein to form a 118 will be more nearly axial and thus less likely to continuous body that will contact selected ones of the cause tilting of the base on the stem 12. The enlarge leads 14 at their interface with the glass body of the ment of the second portion 144 allows easier injection of stem 12. Typically, a depth of about 2.5 mm has been the dielectric material into the fill-hole 136. found to be satisfactory. The recess 32 has a lateral 20 In FIG. 9, another embodiment of fill-hole is shown. dimension sufficient to completely encompass the high A base 218 includes a fill-hole 236 comprising a first voltage lead 14 in the silo 26 and the adjacent lead 14 portion 242 communicating with a recess 232 in the disposed between the silo 26 and the fin 28. The recess wafer flange portion 222 of the base 218, and a second 32 is generally defined by a arcuate boundary which portion 244 offset therefrom and disposed nearly coaxi passes through the centers of the rest of the leads 14. 25 ally of the base 218. The second portion 244 is ex However, fillet-like cavities 34 provided at each of the tremely enlarged relative to the first portion 242, similar other leads 14 allow dielectric material injected into the to that provided in the fill-hole 136 shown in FIG. 8. recess 32 to also surround those leads as well where Also shown in FIG. 9 is a piston 250 preferably hav they enter the stem 12. ing a rubber O-ring 252 at one end thereof. The piston In actual practice not all leads will have high voltages 30 250 is adapted to be received snuggly within the second applied to them and hence need not be surrounded by portion 244 of the fill-hole 236. Thus, a charge of dielec the dielectric material. To this end, in a preferred prac tric material can be disposed in the second portion 244 tice with the base 18, the dielectric material is forced and then the piston 250 advanced thereinto to force into the recess 32 until it encompasses the high voltage dielectric material into the first portion 242 and into the lead 14 in the silo 26 and the lead 14 between the silo 26 35 recess 232 of the base 218. and the fin 28, and spreads further across the recess 32 Referring again to FIG. 1, the stem 12 includes a glass until about half of the lateral dimension of the recess is drip 37 at the periphery of the stem 12 which extends a filled. short distance beyond the otherwise even periphery of In order to access the recess 32 for the purpose of the stem. The drip results from the conventional proce injecting plastic dielectric material thereinto, a passage 40 dure employed in fabricating neck-stem structures as way or fill-hole 36 (FIGS. 2, 3, and 6) is provided in the described hereinabove. The novel base 18 is provided base 18, preferably in a wall of the housing 20, and with drip relief means which allows the base to be extends from the distal end thereof to the opposite end seated axially aligned with its tube. This means is pro of the base 18 where it communicates with the recess 32. vided in the form of an annular shoulder 38. The shoul Dielectric material can be dispensed through the fill- 45 der 38 allows the drip 37 to be received radially out hole 36 simply by positioning a dispenser nozzle at the wardly from the shoulder into a recessed portion of the distal end thereof. Since the fill-hole 36 has a uniform wafer flange 22. volume from base to base, a specific metered amount of The drip relief means may be thought of simply as the dielectric material can be dispensed thereinto such that removal of an annular peripheral portion of the wafer it will fill the fill-hole 36 and enter the recess 32 with a 50 flange 22 to produce the shoulder 38, or as an annular slight overflow into the housing 20 around the exhaust ridge disposed on the end surface of the wafer flange 22 tubulation 16. Thus, regardless of the volume of the having the shoulder 38 as one side surface thereof. Ex exhaust tubulation 16, the recess 32 can be filled without perience has shown that in conventional procedures fear of overflow out of the base 18 thereby causing used to seal a stem 12 to the neck section of a picture messy spillage. 55 tube, the largest drips 37 which are normally produced In order to insure a complete filling of that portion of can be relieved by a shoulder 38 which is approximately the recess 32 in the region of the silo lead 14, the recess 0.75 mm high. is divided into two sections. A first section 32c is arcu To better insure that the dielectric material thor ate in shape and encompasses the fill-hole 36, the silo oughly surrounds the silo lead 14, a portion of the drip lead 14, and the adjacent lead 14 between the silo 26 and 60 relief ridge 38 can be either cut away adjacent to the silo fin 28. A second section 326 is constituted by the re lead 14, or it can be displaced away from the lead. mainder of the recess 32. The first section 32a is par FIG. 10 illustrates a base 318 which differs from the tially separated from the second section 326 by a lip 35 base 18 in that it has a discontinuous drip relief ridge 338 (FIGS. 3, 4, 6 and 7). Thus, when dielectric material is with a portion thereof cut away adjacent to the silo lead injected into the recess 32 from the fill-hole 36, it enters 65 314. This produces a gap 339 which allows the dielec the first section 32a and substantially fills it before it tric material to better flow around the silo lead 314. spills over the lip 35 into the second section 326. This Alternatively, the ridge may be made discontinuous insures a thorough encompassing of the two leads 14 in in a number of places so that it contacts the stem 12 with 4,076,366 a plurality of short sections, which function somewhat acceptable dielectric properties is that sold by General in the nature of a plurality of feet on the base which abut Mills under the trade name Versalon 1138. the stem 12. The preferred embodiment of the ridge Materials suitable for the base itself are hard strong shoulder is that it be as fully continuous as possible and ones which have good dielectric properties and can be still allow adequate insulation around the high voltage 5 easily molded to the desired shape. Such materials in lead. When the ridge shoulder is completely continu clude glass filled plastic resins. A preferred material is ous, it serves the additional function of providing a dam one sold under the trade name of Celanex 3310 by Cel- or seal wall for the plastic dielectric material which is anese Plastics Company. injected into the recess. This allows the production of a What is claimed is: neater, cleaner product. 10 1. A base member adapted to be disposed over an FIG. II illustrates a base 418 which differs from the array of lead conductors and an exhaust tubulation ofan base 18 in that it has a drip relief ridge 438 which in electron tube, said base member comprising: cludes a sharp arcuate section 441 adjacent to the silo a. a tubular housing having an open end for receiving lead 414. The arcuate section 441 is displaced away said exhaust tubulation therein, from the silo lead 414 more than the drip relief ridge 38 IS b. a flange extending outwardly from said housing at of the base 18 so that the dielectric material can better said open end thereof, flow around the silo lead 414. c. an array of apertures through said flange for re FIG. 12 illustrates a base 518 useful in applications with less severe high voltage breakdown problems. The ceiving said array of conductors therethrough, d. a recess in said flange encompassing said open end base 518 is of the wafer type with a tubulation housing 520 and a wafer flange 522 at the open end of the hous ing. An array of leads 514 from a stem structure 512 are received through an array of apertures in the wafer flange 522, and are free standing. The flange 522 is provided with a recess 532 in the face thereof adapted to abut the stem 512. At least one of the leads 514 passes through the wafer flange 522 within the recess 532. A dielectric fill-hole 534 is provided through the wafer 20 2S and at least one of said apertures, and e. a passageway in said base member separate from the tubulation receiving cavity of said housing and opening into said recess. 2. The base member of claim 1 wherein said passage way is through said flange. 3. The base member of claim 1 wherein said passage way is in the wall of said tubular housing. flange 522 and opens into the recess 532 for injecting 4. The base member of claim 3 wherein said passage dielectric material into the recess around the leads 30 way extends longitudinally along said tubular housing therein. Optionally, one or more fins 528 may be pro wall from one end thereof to the other. vided along the housing 520 between adjacent leads 514 5. The base member of claim 4 wherein said passage to improve high voltage breakdown. way has a bend therein so that the opening of said pas As shown in FIGS. 2, 3 and 5, a blind bore 40 is sageway at the distal end of said tubular housing is provided in the housing 20 at one of the lead locations 35 offset toward the longitudinal axis of said tubular hous such that a lead 14 from the stem 12 can be received ing. therein. No external contact is accessible to this lead 4. The base member of claim 4 further comprising a from the base 18. The purpose of this structure is to piston within said passageway for forcing material permit use of a universal type stem 12 having a fixed through said passageway and into said recess. number of leads 14 even though some of them will not 40 7. The base member of claim 3 wherein said wall of actually be used to make contact with any electrodes said housing is longitudinally grooved with the grooves inside the picture tube itself. Whereas only one such being adapted to receive said conductors in the bottoms bore 40 is shown in the drawings, additional blind bores thereof. may be provided at other lead locations. 8. The base member of claim 3 further comprising a A lead 14 may also be disposed in the fill-hole 34. To 45 tubular silo disposed alongside said tubular housing wall this end, the fill-hole 34 is located at one of the regular and closed at one end by said flange and open at the lead locations in the circular arrays of leads 14. opposite end thereof for receiving one of said conduc Materials suitable for use as the dielectric are those tors therein. which can be injected in liquid form and then hardened 9. The base member of claim 1 wherein said recess to produce a good dielectric insulator body. The sili- 50 comprises two sections partially separated by a lip, cone rubbers are useful in this respect but suffer from whereby material injected from said passageway into the disadvantage of requiring a rather lengthy curing one of said sections will substantially fill that section time which causes a slow down on the production line. and then spill over said lip into the other of said sec Preferred materials are the hot melt polyamide resins tions. which are thermoplastic. One such resin found to have 55 60 65