US3518477A - Compact cold cathode indicator tube - Google Patents

Description

Jame 3Q, 1970 R. B. FEHNEL COMPACT COLD CATHODE INDICATOR TUBE Filed Sept. 8, 1967FIG 2 FIG! INVENTOR. RICHARD B. FEHNEL United States Patent O 3,518,477 COMPACT COLD CATHODE INDICATOR TUBE Richard B. Fehnel, Basking Ridge, N.J., assignor to Burroughs Corporation, Detroit, Mich., a corporation of Michigan Filed Sept. 8, 1967, Ser. No. 666,439 Int. Cl. H01 7/42 US. Cl. 313-1095 3 Claims ABSTRACT OF THE DISCLOSURE The disclosure is of an indicator tube including large, rugged, insulating plates spaced apart and securing the tube cathodes between them. The cathodes are held in place by mounting tabs which engage the large-area disks.

A generally cylindrical anode structure is secured in place between the large-area top and bottom plates, and all parts interlock to form a strong, rigid assembly.

BACKGROUND OF THE INVENTION 3,518,477. Patented June 30, 1970 20. The top and bottom plates 40 and 50 have offset central regions 60 and 70, respectively, offset from the main plane of each plate, which extend from front to rear along a diameter perpendicular to the tube axis. Offset region 60 appears as an elevation when viewed from the bottom surface of plate 40, and offset region 70 appears as an elevation when viewed from the top surface of plate 50.

The top and bottom plates are used to support a group of cathode electrodes 72 in the regions 60 and 70, and the facing elevations or offset regions serve to set the cathodes oif from the rest of the plates. The viewability of the cathodes is thus optimized.

The cathodes 72 in tube 10 have a main body portion in the form of a numeral (or any other character) and two mounting tabs which extend from opposite upper and lower portions of the cathodes. One suitable form of herein has certain structural features which provide added advantages for mass production manufacture.

SUMMARY OF THE INVENTION DESCRIPTION OF THE DRAWINGS In the drawing; FIG. 1 is a perspective view of an indicator tube embodying the invention; A

FIG. 2 is a front elevational view of the invention; FIG. 3 is a front elevational view of a modification of the invention; and

FIG. 4 is a plan view of a modification of a portion of the invention.

DESCRIPTION OF THE PREFERRED MEMBODIMBNTS i r V A tube 10 embodying the invention includes a gas-filled glass envelope 16 which has a stem 20 anda viewing window 30. For purposes of illustration, a' side-view tube is shown'in which the viewing window comprises the side wallof .the envelope. The tube 10. includes. relatively strong and rugged top and bottom insulating plates 40' and 50, respectively, of glass or ceramic, preferably a high temperature ceramic. The diameter of plates 40 and 50 is about equal to the diameter of the electrode assembly cathode tab includes a generally trapezoidal (as shown) or rectangular portion 75 and a short-straight portion 77. It is noted that only one complete cathode is shown to simplify the' drawing.

The plates 40 and 50 are provided with apertures 80 which are spaced along the offset regions 60 and 70 and through which the cathode mounting tabs are adapted to extend. The apertures or holes 80 pentrate all the way through ower plate 60, but they need not penetrate all the way through top plate 40. As shown, the apertures 80 are arranged in two rows and are staggered to permit closer spacing of the individual cathodes. The plates 40 and 50' are also provided with transverse slots 84 and 86, respectively, extending across the offset regions 60 and 70. Slots 84 extend upwardly from the lower surface 44 of the top plate in the offset region 60, and slots 86 extend downwardly from the top surface 52 of the bottom plate in the offset region 70. These transverse slots are of a convenient depth and are adapted to receive the relatively large cathode tab portions 75, with the straight tab portions 77 extending into the apertures 80. The tab portions '75 are held in place in the slots 84 and 86, and this prevents the cathodes from twisting. The cathodes are thus held securely in place.

In a modification of the invention shown in FIG. 3, a mass of a suitable cement 108 may be deposited in the depressions 60 and 70 to embed the tab portions 77 and thus hold the cathodes in place. If such a cement is used to secure the cathodes in place, then the transverse slots 84 and 86 and enlarged cathode tab portions 75 are not in tube 10 and about equal to the diameter of envelope 16. In the past, side-view tubes of-this general type have employed very thin mica plates at thetop and bottom of the electrode assembly to assist in holding the assembly together. Such plates might be a fraction of a millimeter in thickness and served minimally in lending rigidity to a tube structure. According to the invention, in a tube having an electrode assembly about one inch in height, plates 40 and 50 might have a thickness of A3 inch or more. Plate 40 has top and bottom surfaces 42 and 44, respectively, and plate 50 has top and bottom surfaces 52 and 54, respectively, and the bottom plate is seated on stem required. Plate 50 without slots 84 is shown in FIG. 4. The cathode tabs in this case would consist entirely of elongated portions 77 whichwould extend directl from thecharacter portion of the cathode.

In either case, the lower cathode tab portions 77 are welded'to tube pins which extend through the depending portion 131 of stem 20 of the envelope. The region of connection between the tabs 77 and pins 130 are positionedin the depression formed by offset region 70 between plate 50 and stem 20.

The tube 10 also includes a generally cylindrical anode comprising a solid rear plate 136 and afront screen 138, both of which include overlapping side panels. These side panels, and particularly the solid side panels 139 extending from the rear plate 136, insure strength and rigidity. The cylindrical anode is positioned between the top and bottom plates, and is secured thereto by means of suitable tabs 140 bent over to engage the plates. A sufiicient number of tabs 140 is provided to insure a strong and rugged coupling of the plates 40 and 50 and the anode. Tabs (not shown) might also be provided to engage holes 141 in top and bottom plates 40 and 50. If desired, the plates 40 and 50 might also be provided with slots represented by numeral 143 to receive the upper and lower ends of the anode screen and plate. This adds to the rigidity of the assembly. The upper and lower ends of the anode screen and plate follow the contour of the surfaces 44- and 52, respectively, of the plates 40 and 50 which they contact.

It is generally customary to include a small quantity of mercury in the usual tube atmosphere of neon, argon. or the like to minim ze cathode sputtering. This mercury may be added with the tube gas, or it may be released from a suitable capsule 1 45 mounted at the rear of the solid anode plate or above top plate 40 or in any other suitable location. The capsule may be of.a type which is fractured to release the mercury, or it can be of the type which is heated to release the mercury. Heating may be by direct current flow or by high frequency induction.

The principles of the invention are set forth clearly above, and those skilled in the art will appreciate that modifications may be made within the scope of the invention. It will also be clear that the tube construction, including the rugged top and bottom plates, the cylindrical anode screen between these plates, and the cathode arrangement, provides a tube assembly which is strong and rugged but is also relatively simple to build and assemble.

What is claimed is:

1. A side view cathode glow indicator tube including an envelope filled with an ionizable gas capable of sustaining cathode glow,

said envelope including a viewing window portion along one side and a stem at one end through which tube leads extend for connection to electrodes inside the envelope, said envelope being normally oriented vertically and said stem being normally oriented horizontally,

a self-contained electrode assembly including cathode and anode electrodes and top and bottom insulating plates between which and to which said anode and cathodes are rigidly secured,

said anode electrode comprising a generally hollow tubular structure and including a solid rear plate portion remote from said viewing window and extending a distance around the sides of said electrode assembly and a mesh portion positioned adjacent to said viewing window and extending around the sides of said electrode assembly where it overlaps said solid plate portion and is secured thereto to form a generally rigid tubular structure, said solid portion of said anode having a plurality of tabs at its upper and lower ends which engage said top and bottom plates and secure said plates and said anode together in a rigid unitary assembly, said tubular anode structure thus serving also to space said top and bottom plates apart a predetermined distance,

said cathode electrodes being oriented vertically in parallel planes facing said viewing window with each cathode electrode including a main body portion in the shape of a character and an upper mounting tab and a lower mounting tab,

said top and bottom plates having a smaller lateral dimension than said stern,

said bottom plate being seated on said stem whereby said self-contained electrode assembly is supported on said stem,

said bottom plate including lateral coplanar portions each having a top surface and a bottom surface which rests on the top surface of said stern, said bottom plate also including a first central elevated portion which is generally in the shape of an inverted U which is oriented along a diameter of said bottom plate generally perpendicular to the planes defined by said cathode electrodes,

said elevated portion having a top surface which is spaced from the top surfaces of said lateral coplanar portions thereof and a bottom surface which is spaced above the top surface of said stem on which said first plate is seated,

said first elevated portion including a plurality of first apertures which extend through said plate,

each said lower cathode tab being positioned in and substantially completely concealed in one of said first apertures with the adjacent main body portion of the cathode positioned closely adjacent to the top surface of said first elevated portion,

each said lower cathode tab being secured to a tube lead beneath the top surface of said first elevated portion, said top plate including lateral coplanar portions each having a top surface and a bottom surface and a second generally U-shaped central elevated portion which is oriented along a diameter of said top plate generally perpendicular to the planes defined by said cathode electrodes and generally parallel to said first central elevated portion of said bottom plate,

said second elevated portion of said top plate including a plurality of second apertures, each of which receives one of said upper cathode tabs, each said upper cathode ta'b being substantially completely concealed in one of said second apertures, with the adjacent main body portion of each cathode being positioned closely adjacent to the bottom surface of said second elevated portion of said top plate,

whereby substantially only said main body portion of each cathode electrode is exposed to view between said first and second elevated portions of said top and bottom plates.

2. The tube defined in claim 1 wherein said bottom plate includes transverse slots, in said first elevated portion, which intersect said first apertures, and each lower cathode tab comprises a relatively large, flat disk which is positioned in one of said transverse slots and prevents rotation of its cathode out of its predetermined plane of orientation facing said viewing window.

3. The tube defined in claim 1 wherein a space is provided along said first elevated portion between its lower surface and the top surface of said stern, and a cement is provided in said space wherein said lower cathode tabs and their tube leads are rigidly secured.

References Cited UNITED STATES PATENTS 2,991,388 7/1961 Wightman 313-1095- 3,005,92Z 10/1961 Hart 313-1095 3,242,370 3/1966 Milliken 313-1095 3,250,938 5/1966 Frouws et al. 313-1095 3,302,052 l/ 1967 Schwab 313-1095 3,358,176 12/1967 Rosenberg et al. 313-1095 2,618,697 11/ 1952 Metcalf 313-1095 3,437,861 4/1969 Koshizuka et al. 313-31-8 X FOREIGN PATENTS 1,127 466 4/1962 Germany.

ROBERT SEGAL, Primary Examiner

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