US2488132A

US2488132A - Deflection system for cathode-ray tubes

Info

Publication number: US2488132A
Application number: US706727A
Authority: US
Inventors: Leighton Herndon Wheeler
Original assignee: Allen B du Mont Laboratories Inc
Current assignee: Allen B du Mont Laboratories Inc
Priority date: 1946-10-30
Filing date: 1946-10-30
Publication date: 1949-11-15
Anticipated expiration: 1966-11-15

Description

Nov. 15, 1949 H. w. LEIGHTON DEFLECTION SYSTEM FOR CATHODE-RAY TUBES 3 Sheets-Sheet 1 Filed Oct. 30, 1946 JNvmwan Nov. 15, 1949 H. w. LEIGHTON 2,488,132

DEFLECTION SYSTEM FOR CATHODE-RAY TUBES Filed Oct. 30, 1946 3 Sheets-Sheet 3 |llll llllllll we? IZILJIIII all H r1 i M .15 M1 I lfivewrofi Patented Nov. 15, 1949 DEFLECTION SYSTEM FOR" CATHODE-RAY TUBES Herndon Wheeler Leighton, Hackensaok, N. J assignor to Allen B. du Mont Laboratories, Inc., Passaic, N. J., a corporation of Delaware Application October 30, 1946, Serial No. 706,727

6 Claims.

This invention relates to a cathode-ray tube and more particularly to the deflection system thereof.

In accordance with this invention provision is made for connecting coaxial cables to deflection plates of cathode ray tubes and these plates are so shielded that very high frequencies can be applied to them with .a minimum of interference from outside sources. Also, the inductance of the circuit is kept low and capacitances between electrodes of the tube are minimized.

In carrying out the invention, provision is made so that the outer conductors of coaxial cables. can be attached to threaded connectors that are made up of several pieces that pass through the wall of the neck of the tube. The length of the conductors inside oithe neck is very short due to the fact that the conductors enter the neck radially.

A shield is provided inside of the neck of the tube around the deflection plates to protect them.

from external interference and another shield is provided to separate the horizontal from the vertical deflection plates to prevent the two fields from interacting or influencing each other.

The invention maybe understood from the description in connection with the accompanying drawings, in which:

Fig. 1 is a longitudinal section through the neck of the tube partly broken away.

Fig. 2 is a perspective view of the rings that hold the deflection plates and their connectors in position.

Fig. 3 is a perspective view of one of the outer coaxial connector bushings.

Fig. 4 is a plan view of the deflection plate assembly and,

Fig. 5 is a side View of the deflection plate assembly partly along the section 5-5 of Fig. 4.

Fig. 6 is a plan view of a modified form of the deflection plate assembly shown as a section across the neck of the tube to show how the assembly is mounted.

Fig. 7 is a longitudinal section through the neck of the tube, as shown in Fig. 6, partly broken away.

In the drawings, reference character I indicates a portion of the neck of a cathode-ray tube through the walls of which four coaxial connectors extend. A portion 2 of each coaxial assembly is anchored in the neck I and makes contact with the outer coaxial connector bushing 3 that is held in place by the seals consisting of a corn plaster shaped piece of ceramic 4 and cement 5.

The bushing 3 which is externally threaded to receive the outer lead of the coaxial cable has .s

strucksout tabs 3a to form a tight fit in the tubular connector 2. This bushing is flanged at..3.' to hold its position againstthe neck of the tube I. Each one. of these bushings is inserted into a connector 2 and is cemented to the glass neck I by seals it and 5.

The inner end of portion 2 fits into a connecto cable. This slit portion is supported by the ring of insulating material 9 and is spot welded at II to the deflection plate-lead I2. which supports the deflection plate I3.

Metal rings I4 and I5 (Figs. 1 and 2) are pro vided with grooves I4 and I5 and are clamped together by bolts I6- and nuts lfi' to hold these rings on the connectors 6. These connectors B are cemented to the rings 14 and I5 as indicated Electrostatic shields I1 and I 8 that have flanges I? and I8 are bolted onto the deflectionplate assembly by nu.s IS on the bolts I6. A disc shaped shield I9 (Fig. 5) having a central hole- It for the electron beam is clamped between the discs I4 and I5.

In the final assembly of the tube the deflection plate sub-assembly as shown in Figs. 4 and 5'may be attached to the electron gun structure, not

shown. The stem carrying the electron gun structure and the deflection plate assembly is then inserted in the neck of the tube and adjusted until the deflection plates are at the proper distance from the screen of the tube. The stem is then sealed in place. Each of the flanged portions 2 of the deflection plate assembly will then be in close proximity to the inside wall of the neck I of the tube. The glass of the neck I is then heated and pushed down around the flanged portions 2 so as to complete a vacuum tight seal at this point. Holes are then melted through the glass over these flanged portions 2 permitting the connectors 3 to be inserted so as to give good electrical contact between them, with the flange 3 resting on the seal between the neck and the curved portion of 2. The corn plaster shaped seals 4 are then put in place over flange 3' and affixed with cement 5 so as to hold flange 3' firmly in place with respect to the curved portion 2 to complete the operation.

Figs. 6 and '7 show a modification of the deflec- 3 tion plate assembly and the way it is mounted in the neck of the tube.

As shown in these figs. the part 20 corresponding to part 2 of the other figs. does not have the curved flange shown in Figs. 1, 4 and 5 at the point where it fits into the glass. It goes straight through and a threaded and flanged piece 2| fits over it and receives the outer coaxial connector on its threads.

In this modification, a conductor 22 connects the inner conductor of the coaxial line with the connector [0 attached to connector II that supports the deflection plate I 3. It is supported along the axis of the outer connector 20 by a bead 23 of glass which provides a vacuum tight seal.

The deflection plate lead assembly shown in Figs. 6 and 7 is held in position by threaded metal pieces 24 and 25 which fit each other and the sleeve 20 and are so arranged as to make good electrical contact between the parts 20 and 26.

The transverse shield 21 of the deflection plate I3 is constructed with a recess 28 to receive the deflection plate connectors.

In the final assembly according to Figs. 6 and 7 the deflection plate assembly without the bushing 2| is inserted into the tube neck. After locating the deflection plate assembly the tube neck is heated and sealed about the four connectors 20 to the tube body. The bushings 2| are then slipped over the protruding portions of the sleeves 20 and are sealed in place as before with the cornplaster shaped seals 4 and the cement 5.

What is claimed is:

1. In a cathode-ray tube having deflection plates, a metal shield for said plates, means to connect the inner conductor of a coaxial cable to each of said plates through said shield and means to attach the outer conductor of said cable to said shield.

2. The device of claim 1 in which the last mentioned means of attachment of the outer conductor of said cable to the shield comprises a tubular member with one end set in the shield and the other set in the glass neck of the tube and protruding from it with this protruding portion adapted to receive the outer conductor of the coaxial cable.

3. The device of claim I in which the last mentioned means of attachment of the outer conductor of said cable to the shield comprises a tubular 4 member with one end set in the shield and the other having a recurved flange and set in the glass neck of the tube and a bushing having its outer portion adapted to receive the outer conductor of a coaxial cable inserted into the flanged portion of the tubular member.

4. In a cathode-ray tube, a plurality of coaxial lines passing through the wall of the neck of said tube and each having its outer conductor hermetically sealed in said wall and a shield for deflection plates in said tube to which the outer conductor of each of said cables is attached.

5. In a cathode ray tube having two pairs of deflection plates, a cylindrically shaped metal shield for said plates, means to connect the inner conductor of a coaxial cable to each of said plates through said shield and means to attach the outer conductor of said cable to said shield, and comprising two pairs of semi-cylindrical metallic members attached to said shield and extending inwardly therefrom forming complementary shielding channels for conductors leading to said plates.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,753,317 Rothen Apr. 8, 1930 1,937,849 Slack Dec. 5, 1933 2,245,581 Ekstrand June 17, 1941 2,268,194 Glass Dec. 30, 1941 2,360,660 Eaton et al. Oct. 17, 1944 2,404,085 Okress et al July 16, 1946 FOREIGN PATENTS Number Country Date 479,961 Great Britain Feb. 15, 1938