US2806279A

US2806279A - Process for installing lead in a directviewing storage tube

Info

Publication number: US2806279A
Application number: US496683A
Authority: US
Inventors: Arnold M Anderson
Original assignee: Hughes Aircraft Co
Current assignee: Raytheon Co
Priority date: 1955-03-24
Filing date: 1955-03-24
Publication date: 1957-09-17
Anticipated expiration: 1974-09-17

Description

Sept. 17, 1957 A. M. ANDERSON ,8 ,2

PROCESS FOR INSTALLING LEAD IN A DIRECT-VIEWING STORAGE TUBE Filed March 24, 1955 Z ShQetS-Sheet 1 Aha 7 401 410 M 44 95/62,

A. M. ANDERSON Sept. 17, 1957 PROCESS FOR INSTALLING LEAD IN A DIRECT-V EWING STORAGE TUBE 2 Sheets-Sheet 2 Filed March 24, 1955 United States Patent PROCESS FOR INSTALLING LEAD IN A DIRECT- VIEWING STORAGE TUBE Application March 24, 1955, Serial No, 496,683

2 Claims. (Cl. 29-2513) This invention relates todirect-viewing storage tubes and more particularly to a process for installing the highvoltage lead to the viewing screen in this type of tube.

In a direct-viewing storage tube, as is generally known, an electric charge pattern is produced on a target element or storage grid assembly to control the flow of flood electrons to a viewing screen to produce a visual presentation of the charge pattern. It is desirable that the flood electrons penetrating through the target element or storage grid assembly be directed to the viewing screen in a collimated flow. The preferred manner of. accomplishing this in present-day direct-viewing storage tubes is to dispose the storage grid assembly immediately adjacent a viewing screen including a conductive coating and impress. a high voltage accelerating potential on this conductive coating. In order to achieve a satisfactory collimated flow and suitable brilliance, it is necessary that this accelerating potential be of the order of several thousand volts positive with respect to the levels of the potentials on the target element or storage grid assembly.

The maintaining of this high potential on the viewing screen has resulted in numerous difficulties. First, it is deemed highly undesirable to bring off a high voltage lead directly from the face of the tube as this made the tube very diflicult to mount flush with an instrument or other type panel. lead may be brought back along the inner surface of the tube envelope so that the high voltage terminal appears several inches behind the viewing face of the tube. In this event, however, the high voltage on the inner lead distorts the electric field between the storage grid assembly and viewing screen so that the flood electrons no longer flow directly to the viewing screen, thus distorting the visual presentation of the charge pattern. In addition, it is very difficult to prevent arcing between the inner lead and the storage grid assembly which are necessarily maintained at a potential difference of the order of several thousand volts. An alternate method is to employ a viewing screen that only uses the central portion of the face plate of the tube envelope. This structure, in addition to being inefficient with regard to space, affords no convenient structure to support the storage grid assembly and electron optical system for the flood electrons.

In accordance with the present invention, a process is provided for installing a viewing screen in a directviewing storage tube whereby the viewing screen extends over the entire face of the tube. In addition, the terminal for applying a high voltage to the viewing screen is disposed several inches back from the face of the tube which has no exposed connecting lead to the viewing screen inside or outside of the tube envelope to interfere with the mounting of the tube or cause arcing to the storage grid assembly.

A general object of this invention is to provide an improved method for installing a high voltage connection to the viewing screen of a direct-viewing storage tube.

In order to overcome this difficulty, the i 2,806,279 Patented Sept; 17, 1957 More specifically, objects of the invention are to increase the arc-over potential between the storage grid assembly and the high voltage lead to the viewing screen and more particularly to locate the terminal connecting the viewing screen several inches back from the face of the tube by a-process whereby the lead therebetween is imbedded in the glass constituting the envelope of the tube.

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in conjunction with the accompanying drawings in which an embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only, and are not intended as a definition of the limits of the invention.

Fig. 1 illustrates a completed viewing screen ina portion of a tube envelope with a lead thereto installed in accordance with the present invention;

Fig. 2 illustrates a cross sectional view of a completely installed lead to the viewing screen showing the relative position of a storage grid assembly; and

Figs. 3 to 8 illustrate steps in the process of making the device of Fig. 1.

Referring now to the drawings, Figs. 3 through 8 illustrate the step in the process of installing the high voltage lead to the viewing screen in a direct-viewing storage tube. More particularly, Fig. 3 shows the initial shape of a high voltage lead 10 which comprises a tail section 11 and a button end 12 having a diameter of the order of Va inch. Lead 1% may be fabricated from metals such as nickel-cobalt-iron alloys known commercially as Kovar or Therlo or other metals capable of being sealed to glass.

The first step in installing the lead 10 in the storage tube is illustrated in Figs. 4, 5, and 6. The purpose of this step is to bead certain portions of the lead 10 with glass to produce a beaded lead 13, as shown in perspective in Fig. 5 and in cross section in Fig. 6. The type of glass employed is preferably borosilicate glass such as, for example, glasses known commercially by Corning Code Numbers 7052, 7055, and 7040. This beading is accomplished by first taking a glasstube 14 having a length of the order of inch shorter than the tail section 11 of lead lil and a bore of sufiicient diameter to slide over the tail section 11. Glass tube 14 is then sealed to the tail section 11 and one side of the button end 12 is headed with the same type of glass. The unbeaded short portion of tail section 1 1 is then bentover on the beaded side of button'end 12, as shown in Figsl 5 and 6.

In the process of the present invention, an enlarged portion 15 of the envelope of a direct-viewing storage tube, shown partially in Fig. 1, is made by assembling a cylindrical portion 16 and a face plate 18, as shown in Figs. 7 and 8. The neck portion of the envelope is not shown. In order to prepare the cylindrical portion 16 for the beaded lead 13, a small notch 20 is made on the extremity of cylindrical portion to be sealed to face plate 18 at the point where it is desired to install the high voltage lead to the viewing screen. The edge of portion 16 may be notched, for example, by the use of a torch 21. The beaded lead 13 is then disposed lengthwise along the portion 16 with the bent portion of tail section 11 in the notch 29 and the glass heated with the torch 21 until the glass constituting the portion 16 is integrally combined with the glass on the beaded lead 13, as shown in Fig. 7.

The next step in the process is to place the face plate in position over the end of cylindrical portion 16, as indicated in Fig. 8, and seal it thereto by means of a plurality of burners 22. During this process the bent portion of the 2,soe,279

tail section 11 of lead is pressed into the inner surface of the faceplate18 while'the glassis in a softened condition so that the exposed portion of the tail section 11 is flush with the inner surface of plate 18. Across sectional drawing showing the face plate 18 sealed in position isfshownin Fig. 2. Referring to this figure, a transparent-conductive coating 24 is then disposed over the entire inner surface of the face plate 18. .In order to'insure electrical contact between the tail section 11 and the transparent conductive coating 24, a silver ring 26 is painted about the inner periphery of the envelope portion 15 on the inner surface of the face plate 18 on the top of the conductive coating 24 and extending over the exposed-portion of tail section 11. A'fluorescent screen 28 is then settled over the entire inner surface of face plate 18 in the usual manner. Alternatively, the silver ring 26 maybe-painted directly on the inner surface ofthe face plate 18in the same location'as before. The fluorescent screen 28 is then disposed only over the portion of the inner'surface of face plate 18 within the ring 26. A thin metallic coating is then evaporated over the entire area of'the inner surface of face plate '18 whereby the metallic coating is maintained in electrical contact with the lead 10 by means of the silver ring 26.

Referring to Fig. 2, there is also shown the position of a storage grid assembly 30 relative to that of the viewing screen. A direct-viewing storage tube incorporating a storage grid assembly of this type is disclosed in a copending application for patent Serial No. 414,992, entitled, ImprovedDirect-Viewing Storage Tube filed on March 9, 1954, by H. M. Smith, S. Hansen, S. T. Smith, and N. I. -Koda. As is apparent from the drawing, there is necessarily a very close spacingbetween the grid assembly 30 and the viewing screen which makes it diflicult to maintain a potential difierence of the order of 10,000 volts therebetween without arcing. Other terminals 32, as shown particularly in Fig. l, are inserted through the wall of'cylindrical portion 16 of the envelope to provide a means for impressing potentials on the elements of storage grid assembly 30. An electron optical system comprising conductive coating 34 may be disposed directly on the inner surface of the enlarged portion 15 immediately adjacent the terminals 32 and the button end 12 of lead 10.

What is claimed is:

1. The process of installing a high voltage lead including a button end and a tail section to the viewing screen in a direct-viewing storage tube including a glass cylindrical section and a circular glass disc having a diameter substantially equal to the outside diameter of said cylindrical sectionv and equal to the desired diameter of the viewing screen of said direct-viewing storage tube, said process comprisingthe steps of beading with glass one side of the button end and the tail section of the voltage lead except for an exposed tip, bending the exposed tip of said tail section towards said one side of the button end of said voltage-lead, notching the edge-of one extremity of said glass cylindrical section at a point where it is desired to install said lead, disposing said beaded lead lengthwise along the outer surface of said cylindrical section with the exposed tip of said tail section protruding inwardly through said notch, sealing the beading on said lead to the glass constituting said cylindrical section, sealing said circular glass disc to said one extremity of said cylindrical section whereby the exposed tip of said lead is flush with the inner surface of said glass disc, disposing a transparent conductive coating over the inner surface of said circular glass disc, painting a stripe of conductive material about the periphery of said disc over the exposed tip of said lead and said conductive coating, thereby to electrically connect said transparent conductive coating to said high voltage lead, and disposing a fluorescent screen on top of said transparent conductive coating to provide a viewing screen.

2. The process of installing a high voltage lead including a button end and a tail section to the viewing screen in a direct-viewing storage tube including a glass cylindrical section anda circular glass disc having a diameter substantially equal to the outside diameter of said cylindrical section and equal to the desired diameter of the viewing screen of said direct-viewing storage tube, said process comprising the steps of beading with glass one side of the button end and the tail section of the voltage lead except for an exposed tip, bending the exposed tip of said tail section 90 towards said one side of the button end of said voltage lead, notching the edge of one extremity of said glass cylindrical section at a point where it is desired to install said lead, disposing said beaded lead lengthwise along the outer surface of said cylindrical section with the exposed tip of said tail section protruding inwardly through said notch, sealing the beading ontsaid lead to the glass CQnStituting said cylindrical section, sealing said circular glass disc to said one extremity of said cylindrical section whereby the exposed tip of said lead is flush with the inner surface of said glass disc, painting a stripe'of conductive material about the periphery and on the inner surface of said glass disc over the exposed, tip of said lead, disposing a fluorescent screen over the area of the inner surface of said glass disc enclosed by said stripe of conductive material, and disposing a thin, metallic layer over the entire inner surface of said glass disc whereby said stripe of conductive material electrically connects said metallic layer to said high voltage lead.

References Cited in the file of this patent UNITED STATES PATENTS