US2802133A - Electron discharge device - Google Patents

Description

Al lg. 6, 1957 HAAS 4 2,802,133

7 ELECTRON DISCHARGE DEVICE I Filed March 28, 1952 2 Sheets-Sheet 1 INVENTOR PAUL HAAS ATTORNEY- Aug. 6, 1957 P. HAAS 2,802,133

ELECTRON DISCHARGE DEVICE Filed March 28, 1952 2 Sheets$heet 2 INVENTOR PAUL HAAS QMMW ATTORNEY ELECTRON DISCHARGE DEVICE Paul Haas, New Hyde Park, N. Y., assignor to Sylvania Electric Products Inc., a corporation of Massachusetts Application March 28, 1952, Serial No. 279,042

Claims. (Cl. 313-318) This invention relates to thermionic discharge devices and particularly to an improved structure for cathode ray tubes. More specifically, the invention pertains to new and novel supporting means for electrodes within an envelope with means for combining a tube base structure with the envelope of the tube. It should be apparent to those skilled in the art that the invention is capable of many applications other than those described in the specific embodiments described below.

Present day cathode ray tubes of which I am aware utilize in one form an evacuated envelope having an enlarged bulb portion with a cylindrical cooperating narrow neck extending therefrom. The neck contains a gun structure having a number of coaxially aligned electrodes supported by side rods disposed generally parallel to, and at a distance from the axis of the tube structure. Means are provided to support the electrodes between the side rods. Notwithstanding the fact that insulation is required between the electrodes, extremely close tolerances are maintained in the spacing of the electrodes, which requires a large number of side rods and supporting means. As a result, present day electron gun structures for cathode ray tubes have been very complex, requiring a large number of parts, numerous welded joints, and a complicated assembly procedure.

The electrode structure described above is usually supported within the envelope by direct extensions of the side rods or of the electrode leads embedded in a glass press or passing through a glass end closure sealed across the cylindrical end of the tube. It is customary to cover the end of the tube in which these leads are sealed with a cup-shaped insulating base having associated contact pins which extend away from the base parallel to the axis of the tube. Some tube structures rely on lead-in conductors which are sufficiently rigid to permit the direct attachment of a socket without the intervening medium of a tube base, but inadvertent bending of such conductors has been found to crank the glass and destroy the utility of the tubes.

As a result of the various mechanical limitations imposed upon cathode ray tubes by the connecting structures at the base of the tube, the necks of the tubes have been somewhat bulky. It has therefore been necessary to utilize large deflecting and focussing coils and rather large amounts of power in order to produce satisfactory deflection and focussing of the electron beam.

'The present invention has for an object the elimination of a separate insulating base for cathode ray tubes.

Another object is the provision of means for supporting the lead-in connectors of the tube by the wall of the cathode ray tube envelope.

Another object of the invention is to provide as part of the tube envelope an insulating electrode support structure having characteristics better adapted to machining and precise dimensional control than structures previously known.

A further object is to provide a vacuum tube having an integral basing structure which provides a solid atent foundation for supporting electrical structures within the tube.

Still another object is to increase the length of voltage breakdown paths between lead-in conductors passing through the tube walls.

A further object is the reduction of the number of parts and welds required in supporting structure for cathode ray tube electrodes.

Another object is the provision of vacuum tube base and lead-in structures which are readily adaptable to assembly by automatic machinery.

Still another object is the reduction in dimension of the cathode ray tube neck to permit gains in deflecting circuit efi'iciency.

Another object is the strengthening of electrode supporting means within the cathode ray tube to provide a greater resistance to shock.

The above objects and other objects which may become apparent in connection with the description which follows, are attained in accordance with an aspect of the present invention by providing as a portion of the vacuum tube envelope ceramic cylindrical wall elements having passages through which connectors are hermetically sealed and providing a supporting surface for a cooperating electrode supporting structure which is sealed to the glass envelope.

In the drawings:

Fig. 1 is a perspective View of a cathode ray tube embodying principles of the invention.

Fig. 2 is a partial View in cross section of the base and gun structure of the cathode ray tube of Fig. 1.

Figs. 3a, 3b and 3c are views in cross section of alternative embodiments of joint structure for use in the base illustrated in Fig. 2.

Fig. 4 is a plan view of the electrode support disc shown in Fig. 2.

Fig. 5 is a view in cross section of a modification of the gun structure and base shown in Fig. 2.

Fig. 6 is a view in cross section of a further modification of the gun and base structure shown in Fig. 2.

Fig. 7 is a plan view of the electrode support disc of Fig. 6.

Fig. 8 is a View in cross section of a modification of the base and gun structure of Fig. 6.

In Fig. 1 of the drawings, the cathode ray tube includes conical section 1, cylindrical glass neck portion 2 which may be integral with or sealed at one end to cone section 1, and glass face plate 3 on or near the inner side of which is placed a fluorescent screen plate. Attached to the other end of neck 2 is a base structure comprising a number of elements hermetically sealed together. Gun support disc 6 is sealed between neck 2 and ceramic ring 18. Second ceramic ring 20 having external contact strips 26 secured thereto, is sealed between ceramic rings 18 and 30. Metal closure 32 seals off the base end of the tube.

In Fig. 2, detail is shown of the base structure of Fig. 1. Gun support disc 6, which is illustrated in detail in Fig. 4, is hermetically sealed on its face 4 to neck 2 of the cathode ray tube. Ceramic cylinder 18 is sealed to lower face 16 of disc 6, and surrounded loosely by flange 14. To this, in turn is sealed slotted cylindrical ring 29 to form hermetically sealed joint 22. Formed contact strips 26 are Wound around the wall of ring 20 in radial slots 21 located at suitable circumferential intervals. Strips 26 are sealed in slots 21 to hermetically close the latter. As an aid in understanding the structure, a contact strip, such as has been inserted elsewhere in the ring, is omitted from its slots 21 at the center of the ring in this drawing. It will be understood that such is not the practice in a completed, vacuum-tight structure, rather that every aperture must be closed in order to preserve an air tight structure. Contact strips 26 are provided at the exterior of ring with raised portions 28 designed to make contact with external socket means. Ceramic ring .30 having a structure similar to ring 18 is in turn sealed to ring 20, while closure member "32,prdv1ded with flange 34, is sealed to the remaining .face 31 of ring30. j t

Figs. 3a, 3b, and 3c illustrate various types of oints which may be used between rings '18, 20, and; For example, ring structures 18a and 20a arelap fitted, ring structures 18b and 20b have a tongue and groove type structure, whereas ring structures 18c and 20c have a simple sloping overlap. Joints between all members maybe formedby applying glass irit in a volatile suspension to the joints. After the suspension medium has evaporated the ,frit is fused to solder the parts together. Other known sealing techniques may be used, as will be explained below.

Returning to Figures 2 and 4, the gun structure is mounted as follows:

Cylindrical electrode 35, having stepped cylindrical section 38 at its base, and having integral flange 36, is inserted in cut-out hole 10 in support disc 6. Holes 8 are provided at suitable intervals in disc 6 about hole 10 and provide passage for air molecules during evacuation of the tube. Electrode cylinder is secured to disc 6 by lugs 12 which are struck out of base 6 and bent over flange 36. Supported in stepped portion 38 of cathode cylinder 35 is cathode insulating disc 44 having a central aperture for receiving cathode cylinder 46 and also hav ing small breather holes 48. Lugs 39 formed out of flange 36 of cylindrical electrode 35 hold cathode insulator disc 44 firmly in place. Cathode cylinder 46 is retained in the central aperture of disc 44 between circumferential portion 50 and crimped end flange 52. Cathode coating 49 is provided on end closure 47 of cathode cylinder 46. Heater 51 is conventionally located inside cathode cylinder 46. Cup shaped grid disc 40 having centrally located electron aperture 42 is welded in place across electrode 35 and is placed a suitable distance away from cathode coating 49.

Vacuum seal 4 between envelope 2 and grid disc 6 may be a glass-to-metal seal, made in a manner well known to those skilled in the art. Seals 16, 19, 29, and 31 may glass frit technique, it has been found preferable to seal disc 6, ring 18, 20, 30, and connecting strips 26 together in one operation, thereby forming an assembly which is convenient for adaptation to automatic operation. This is done by assembling the parts together with an interposed layer of frit or other bonding agent and raising the temperature of the assembly in an oven or other heating device until the bonding agent flows smoothly and forms a joint of the quality desired. It is then practical to assemble the electrodes of the gun in place and electrically connect them to lead-in strips 26, by the use of connectors already well known in the art. An internal connectionto cylindrical electrode 35 need not be made, for external contact may be made through flange .14 on support disc 6 which is in intimate mechanical relation with cylindrical electrode 35. The resulting assembly may then be sealed to the neck of the glass envelope 2 in a conventional way, such as by means of an induction heating arrangement'or a flame.

It may be desirable, in order to avoid oxidizing the electrodes while they are in place, to divide the operation,

Alternatively,

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first sealing a short glass section of neck glass to the gun support disc, then inserting the electrodes, and finally performing a second seal to joint the short section to the neck of the tube. In the last operation, closure member 32 is sealed to the open end of the assembly using a carefully applied local heat. It should be noted that for this assembly sequence the bonding agent used at 16, 20, and 30, and around contact strips 26 should have a rather high melting point, higher in fact, than the melting point of the glass of the envelope. Conversely, the bonding agent used to form joint 31 between ring 30 and closure member 32 should have a sufliciently low melting point so that joints in other portions of the assembly will not be disturbed by the application of heat in final sealing operations.

The insulating assembly thus produced has resulted in the elimination of an external base arrangement for the vacuum tube and of fragile lead-in conductors sealed directly through the glass envelope. The assembly is readily adaptable to automatic assembly operations and techniques.

Figures 5 illustrates an alternative embodiment of the triode gun and supporting structure shown in Fig. 2. Cathode ray tube neck 2 is sealed to rim 66 of electrode structure 62 at joint 60. One piece ceramic cylinder 64 having circumferentially located radial apertures 67 is sealed at 68 to the opposite face of flange 66 of formed electrode 62. Sealed in slots 67 are contact members 70 having turned over ends 72 which serve as contacts for an external socket or connecting means. Dished end closure 74 is sealed at flange 76 to ring 64 and has exhaust tubulation 7 8 at its center.

Electrode structure 62 is formed as a unitary stamping from a piece of metal and provides flanged portion 66 to fit with ceramic ring 63, raised cylindrical portion 80, closed electrode disc portion 32 having electron aperture 84 and knocked out supporting lugs 86 for retaining cathode insulating disc 88. Centrally located in cathode disc 88 is cathode sleeve 9% locked in place by raised circumferential portion 92 and crimped portion 94. Cathode cylinder is closed by flanged disc 96 hearing an electron emissive coating 98 centrally located beneath electron aperture 84 in grid disc 82. Electrode extension cylinder 100 is suitably fastened at its base 102 to the periphery of raised portion 30 of electrode 66. Knocked-in lugs 104 serve to locate extension 100 in place. If desired, the outer end 106 of cylinder 100 may be formed as shown at an angle (rather than perpendicular to the axis of the electron gun assembly) in order to provide electrostatic field needed to cooperate with an external magnet system for ion trapping.

Assembly of the base illustrated in Fig. 5 may be accomplished by juxtapositioning neck 2, cylinder structure 66, and ceramic cylinder 64, in a suitable jig and simultaneously forming the glass-to-metal seal and the metal-to ceramic seal. The metal-ceramic seal may be performed in a manner previously described. The ceramic ring should have contact members 70 preassembled in position, using a higher melting point bonding agent between contact members 70 and slots 67 than is used at joints 60 and 68. The cathode and its supporting disc are then inserted into the tube as a unit, locked in place by lugs 86, and electrical connections made to contact members 70. Finally, by using local heat, seal 76 between ceramic cylinder 64 and end closure 74 is made.

In Fig. 6, another embodiment of invention is illustrated. However, only significant changes in detail will be described below. Where applicable, similar reference members denote similar parts.

In lieu of metallic electrode support disc 6 of Fig. 2, the ceramic support disc 108 illustrated in the plan view of Fig. 7 is sealed between neck 2 of the cathode ray tube and one face of ceramic cylinder 110, the joint being give accurate centering of disc 107 in cylinder 110. The

lower face of cylinder '1-10 is sealed to cylinder 114 thereby sealing in the slot mounted U formed connector strips 113. End closure 116 having lip 118 is sealed to the remaining face of cylinder '1 14 to enclose the base structure.

In Fig. 7, the plan view of ceramic disc 112 shows slots 1'20 and 122 located on concentric circles around hole 124. Slots 120 are adapted to receive extensions 126 of cylindrical electrode 128. As may be seen in Fig. 6, the ends 130 of strips 126 are then twisted to lock cylindrical electrode 128 firmly in place. Welded across cylinder 128 is cup shaped disc 131 having electron aperture 132. In a similar manner, cup shaped electrode 134 provided with strip extensions 136 is locked in place in holes 122 by twist tabs 138. Cathode sleeve 144} may be locked in hole 124 in the manner used in structures of Figs. 2 and 5.

Assembly of this structure is accomplished by sealing together short neck piece 2, ceramic disc 112, and cylinder 110 in a single operation using high melting point glass and bonding mediums. Cylinder 114, in which connecting strips 113 have been scaled, is then sealed to cylinder 110 with a lower melting point bonding agent. Finally, after making electrical connections between the electrodes and connecting strips 112, end closure 116 is sealed on, using still lower point bonding agent.

Figure 8 illustrates another embodiment of the invention in which cup shaped insulating structure 142 supplants disc 108 and cylinder 11%) of Fig. 6. In order to provide a structure on which a glass seal can be made with the gun electrodes in place, tapered face 134 is employed at the junction of neck 2 and cup 142. An inner circumferential boss 146 is provided to deflect heating flames away from outer electrode 148, thereby preventing oxidation. U shaped connecting strips 150 in suitable radial slots in the outer face of ceramic cup 142 serve as conductors between the outside of the tube and the internal electrodes. Flat ceramic end closure disc 150 then seals 01f the assembly. The various electrodes used in this modification are similar in mounting detail to those used in Figure 6, and accordingly are not described. The twist tab 154 has been made longer so that it may be directly joined to the inner ends of connecting strips 150 to provide necessary electrical connection.

When the structure of Fig. 8 is employed, the electrodes are assembled on the face of cup 142 prior to performing the glass seal '144, since boss 146 will protect the electrodes from the flame and undesired oxidation. Consequently, assembly may be accomplished in the following manner. Connecting strips 150 are first clamped in place on cylinder 142. The electrode elements are then inserted, and electrical connections between tabs 154 and strips 150 are made by soldering or some other suitable method. The resulting assembly is inserted into the neck 20 of the cathode ray tube and heat applied to produce seal 144. Finally, using a lower melting point bonding agent, seal v156 is made between cup 142 and end closure 152. In some operations it may be desirable to combine both sealing operations, thereby requiring only one type bonding agent.

While a tetrode gun structure is illustrated in Figs. 6 and 8, it is apparent that a triode structure could equally well be employed. It should also be noted that breather holes through the ceramic supporting disc and similar to those provided in the previous embodiments may be used to facilitate evacuation of air during processing of the tube.

While the invention described herein is shown as embodied in a cathode ray tube, the utility of this device in other portions of the electrical art as applied to vacuum tubes or to other devices will be readily apparent to those 6 skilled in the art. It is not desired that the below appended claims should be restricted to the particular embodiment described, but rather that they should be interpreted in their broadest aspects consistent with the oppositely located on either face, said sections being provided with at least one common hollow channel extending in the same general direction as said axis and communicating with said slots; and a plurality of electrical conductors, each conductor extending through a pair of oppositely located slots into said common channel.

2. In an electron discharge device, first and second cylindrically shaped electrical insulator members joined to each other in a manner in which both members have a common vertical axis, said members being provided with at least one common hollow channel extending in the same direction as said axis, said second member having first and second vertically separated sets of radially disposed apertures communicating with said channel, the apertures in said first set being opposite the apertures in said second set; and a plurality of electrical conductors, each conductor being sealed in a different pair of apertures, each pair being formed from one aperture in the first set and a corresponding aperture in the second set, and extending onto the outer surface of said second member, said conductors also extending through said common channel.

3. A device as set forth in claim 2 wherein said conductors are provided with first conductive sections lying against the inner surface of the second member and second conductor sections lying against the outer surface of the second member.

4. A device as set forth in claim 3 wherein each of said sections have a strap-like shape.

5. An electron discharge device having a plurality of electrodes, an hermetically sealed envelope for said electrodes having a first substantially cylindrical section joined to a second substantially cylindrical section in such manner that both sections have a common axis, said second section being formed of a number of insulating rings having cylindrical outer surfaces, cylindrical inner surfaces, and plane faces, two of said plane faces having radially located conductor receiving apertures, the apertures in one of said two faces being aligned with the apertures in the other of said two faces, both said sections having at least one hollow common channel extending in the same direction as said axis and communicating with said apertures; and a plurality of electrical conductors, each conductor extending through a different pair of apertures into said common channel, one aperture in each pair being in said one face, the other aperture in said each pair being in said other face.

References Cited in the file of this patent UNITED STATES PATENTS 2,173,906 Katsch Sept. 26, 1939 2,486,065 Saucet Oct. 25, 1949 2,553,425 Schmidt May 15, 1951 FOREIGN PATENTS 946,837 France Dec. 27, 1948

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