US3432803A

US3432803A - High voltage connection for cathode ray tube

Info

Publication number: US3432803A
Application number: US705665A
Authority: US
Inventors: Nathan C Nice
Original assignee: Philco Ford Corp
Current assignee: Space Systems Loral LLC
Priority date: 1968-02-15
Filing date: 1968-02-15
Publication date: 1969-03-11
Anticipated expiration: 1986-03-11

Description

March 11, 1969 N. c. NICE 3,432,803

HIGH VOLTAGE CONNECTION FOR CATHODE RAY TUBE Filed Feb. 15, 1968 INVENTOR.

United States Patent 7 Claims ABSTRACT OF THE DISCLOSURE High voltage lead-in connection for television picture tubes of the kind comprising a separately formed face plate frit-sealed to a bulb portion. The lead-in comprises a metallic supply conductor extending from the outside of the tube through the frit and having a portion bearing resiliently against conductively coated areas of the interior of the tube.

Background of the invention It has been known in the prior art to provide cathode ray tubes with high voltage lead-in connectors which are inserted through and sealed in the wall of the tube bulb or envelope after the envelope has been fabricated. Constructions of this kind involve considerable cost and introduce various complexities, including the need to relieve stresses set up in the wall of the envelope as a result of the insertion procedure.

Recently it has become desirable to fabricate certain types of tubes, for example, low cost black and white tubes, and color tubes which include a shadow mask, by providing a substantially flat face plate formed separately from the tube bulb portion, and then frit-sealing planar A surface portions of the plate directly to the free edges of the flared portion of the bulb.

Summary of the invention My invention involves recognition of the fact that tubes fabricated in this way readily may be provided with an exceedingly inexpensive high voltage connection, and it is the primary object of the invention to provide such a connection in tubes of this type. In addition, the apparatus provides a very simple way of connecting the tube screen to the anode. For these purposes I provide a metallic lead-in connector which is disposed in and sealed within the frit, or other sealing material, during assembly of the tube face plate with the bulb. End portions of the lead-in connector, preferably both free ends thereof, comprise wound spring-like sections one of which bears resiliently against conductive coatings overlying the interior surfaces of face plate and bulb, and the other of which is disposed outside the tube and is available for connection to a high voltage source.

The invention is also featured by the ease with which the outer coil may be connected with such source, and for this purpose it is contemplated that the conductor leading from the source terminate in a substantially flat piece of metal forceably held between adjacent turns of a spring coil forming the external end of the lead-in connector.

Brief description of the drawing FIGURE 1 is a perspective illustration, partially in section, of a cathode ray tube embodying my invention;

FIGURE 2 is a sectional view of a corner portion of the tube illustrated in FIGURE 1; and

FIGURE 3 is a perspective illustration of a coil-spring lead-in connector usable in the practice of the invention.

Description of the preferred embodiment With particular reference to FIGURE 1, the invention is shown as embodied in a cathode ray tube comprising a bulb funnel portion 10 having a separately formed face plate 11 sealed to the free peripheral edge 12 of the tube bulb portion. The tube includes gun structure 13 and an external conductive coating 14. The usual phosphor screen 15 is shown as applied to the rear surface of the face plate 11 and is provided with a conductive layer 16, preferably consisting of vapor deposited aluminum. In actual practice, the layer 16 is very much thinner than appears in the drawing. However the nature and function of the gun structure, and the various coatings, are well known in the art and require no detailed description herein.

In accordance with known practice, the interior of the bulb is provided with a coating of graphite, shown at 17, which, when the tube is in use, is maintained at the anode voltage. This graphite coating extends to the forward edge of the tube at least in the vicinity of one corner portion shown to advantage in FIGURE 2. In the manufacture of such a tube, the face plate and bulb are fabricated separately, and the face plate is then sealed to the free edge 12 of the flared portion of the bulb. For this purpose it is preferred to employ the usual frit, which is clearly shown at 18 in FIGURES 1 and 2. F01- lowing oven baking the layer of frit serves as the structural connection and seal between face plate 11 and bulb portion 10.

In particular accordance with this invention, the anode voltage lead-in connector comprises a spring wire member 19 having a short straight portion 20, and at least one wound spring-like coil section 21 which bears resiliently, and in good conductive relation, against both the aluminum coating 16 and the graphite coating 17, as clearly appears at 22 and 23, respectively, in FIGURE 2. Preferably the straight portion of the spring terminates in a second wound spring section 24 which is adapted for connection to a high voltage source, not shown.

In fabricating the tube, the double wound coil spring 19 is snapped over a corner portion of the free edge of the tube bulb, its resilience tending to hold it in position throughout subsequent assembly and baking operations. Spring Wire of suitable conductivity and having a diameter of .020 inch has been found satisfactory for the lead-in connector. After the spring has been positioned as described above, and the coil section 21 is in position to bear resiliently against the aluminum and the graphite coatings, it is preferable to butter frit around the spring to insure a good seal. As will be understood frit is also applied to the entire forward edge 12 of the tube bulb and, if desired, to confronting surfaces of the rear side of the face plate. With the spring in the position described above, the face plate is positioned with respect to the tube bulb or funnel and the assembly is oven baked to complete the fritting cycle. After the baking operation the portion 20 of connector 19 becomes sealed Within the frit as shown in FIGURE 2 with the coil section 21 hearing resiliently against coatings 16 and 17.

The invention is featured not only by the extremely simple and inexpensive high voltage connection which it provides, but also by the ease with which the outer portion of the lead-in element may be connected with the high voltage source. For this purpose it is contemplated that the conductor leading from said source, a portion of which appears at 25, terminate in a substantially fiat piece of metal preferably having a lanced or roughened surface, as shown at 26, and being of a thickness such that it can be inserted between adjacent turns of the exterior coil 24, as shown in FIGURE 2, and forceably held in that position.

I claim:

1. In a cathode ray tube of the type having a separately formed face plate sealed to a tube bulb or funnel and conductive material extending across interior surfaces of said face plate and bulb into close adjacency with the region of the seal therebetween, a lead-in device comprising a metallic supply conductor extending from outside said cathode ray tube through the seal and having a portion disposed within the tube and bearing resiliently against said surfaces.

2. A cathode ray tube in accordance with claim 1 and further characterized in that said last mentioned portion comprises a spring-like coil member.

- 3. A cathode ray tube in accordance with claim 2 and further including a second spring-like coil member formed as an extension of said supply conductor and disposed outside said tube.

4. In combination with a cathode ray tube of the type having a separately formed face plate frit-sealed to a tube bulb portion and conductive coatings extending across both said face plate and said bulb portion and into close adjacency with the region of the seal therebetween, a lead-in device including a metallic supply conductor extending from the outside of said cathode ray tube through the seal and into the space within the tube, the inner end of said supply conductor comprising a wire spring, portions of which are disposed to bear resiliently against both the mentioned conductive coatings.

5. As a lead-in connector for cathode ray tubes, an electrically conductive member having a substantially straight wire-like portion adapted to extend through the area of seal between separately fabricated tube face 4 place and funnel parts, each end of said wire-like portion being provided with a wound spring coil'section, spaced from one another for resilient engagement with interior and exterior surfaces of such a tube.

6. A glass article comprising separately formed funnel and plate parts, joined with the free edge of the funnel part sealed against one face of the plate part, said article including: an electrically conductive metallic spring-like member including a wire-like section retained in and extending through the seal between said funnel and plate parts; and a spring section comprising an extension of said wire-like section and disposed within the tube with portions bearing resiliently against both said funnel and face plate parts.

7. A glass article in accordance with claim 6, and further characterized-in that a layer of frit comprises the seal between said funnel and plate parts, said wire-like section extends through and is sealed within the frit, and said spring section is of coil form.

References Cited UNITED STATES PATENTS 2,203,048 6/ 1940 Farnsworth et al 313-68 2,269,156 1/1942 Kling 17450.52 2,270,337 1/ 1942 Pensak 339144 FOREIGN PATENTS 931,148 8/1955 Germany.

RICHARD E. MOORE, Primary Examiner.

US. Cl. X.R. 339256