US3543072A

US3543072A - Color cathode ray tube with metallic contactor ribbon bonded on inside wall of tube between the high voltage terminal and the shadow mask frame

Info

Publication number: US3543072A
Application number: US816537A
Authority: US
Inventors: William H Mcneill
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1969-04-16
Filing date: 1969-04-16
Publication date: 1970-11-24
Anticipated expiration: 1987-11-24

Description

Nov. 24, 1970 Filed April 16, 1969 W. H. M NEILL COLOR CATHODE RAY TUBE WITH METALLIC CONTACTOR BONDED ON INSIDE WALL' OF TUBE BETWEEN THE HIGH Ill VOLTAGE TERMINAL AND THE SHADOW MASK RIBBON ATTORNEY Nov. 24, 1970 w. H. M NEILL 3,543,072

COLOR CATHODE RAY TUBE WITH METALLIC CONTACTOR RIBBON BONDED ON INSIDE WALL OF TUBE BETWEEN THE H IGH VOLTAGE TERMT AL AND THE SHADOW MASK FRAME Filed April 16, 1969 2 Sheets-Sheet 2 I 54 k 1 \\\l 7 32 zs KdPZZ INVENTOR. WILLIAM H. Me NEILL United States Patent US. Cl. 313-85 4 Claims ABSTRACT OF THE DISCLOSURE In glass color cathode ray tubes a means for applying the high voltage to the shadow mask frame which comprises welding or otherwise fixing one end of an electrically conductive metallic ribbon directly to the second anode button and forming the other end as a spring to contact the shadow mask frame. Intermediate the welded end and the spring formed end the ribbon is frit sealed to the interior surface of the tube wall. Alternatively, the other end of the ribbon may be formed as a broadened spring contacting portion and a conventional, although much stronger contact spring may be utilized therewith.

BACKGROUND OF THE INVENTION This invention relates to electrical contactors and more particularly to contactors for achieving an electrically conductive path from the second anode or high voltage lead of a glass cathode ray tube to the shadow mask frame thereof.

Current cathode ray tubes for the reproduction of color images comprise an all glass envelope formed from two major pieces; namely, a funnel-shaped body and a face panel.

The face panel is generally dish-shaped with an upstanding peripheral wall. The screen of the tube, which comprises a pattern of different colored light emitting phosphors, is disposed on the interior surface of the face panel. A shadow mask assembly, comprised of a relatively fragile foraminated structure attached at its peripheral edge to a relatively rigid frame, is supported Within the face panel by means of springs attached to the sides of the frame and studs attached to the inside surfaces of the panel walls.

After the screen is formed the face panel is sealed, as by a glass frit, to the wide end of the funnel-shaped body. The narrow end of the funnel is formed to provide a cylindrical neck which receives the one or more electron guns necessary to energize the phosphors to luminescence.

For the electrons emitted from the guns to achieve a sufiicient velocity to correctly excite the phosphors the final anode electrode of the guns has applied thereto a relatively high voltage in the neighborhood of 25 kv. For proper operation of the tube it is desirable that this voltage also be applied to the shadow mask, usually via the frame. To accomplish this, current tubes utilize an electrically conductive coating, usually Aquadag, on the interior surface of the funnel. One end of the coating extends into the neck of the tube and the other end to a position closely adjacent the panel seal area. Snubbers on the final anode of the gun or guns contact the coating in the neck and thus apply the voltage thereto.

While the various voltages necessarily fed to the other electrodes of the guns are carried via pins formed at the terminus of the neck, the high voltage is applied to the coating by means of an electrically conductive metallic button which is hermetically sealed in a wall of the funnel. A suitable source of high voltage is provided in the television receiver and is connected to the button by any suitable means.

3,543,072 Patented Nov. 24, 1970 A contact spring attached to the frame extends upwardly into the funnel and provides the electrical path to the coating. Numbers of contacts for achieving the abovedescribed path are known in the art. However, problems exist with all known forms. One of the major problem areas exists in relation to shock resistance; i.e., under mechanical shock and the subsequent vibrations therefrom being passed onto the contact spring, electrical contact is momentarily lost between the conductive coating and the frame, resulting in a temporary loss of picture. In an attempt to counteract this eifect the springs have been formed of a heavier material to exert greater force upon the conductive coating. This technique introduces other problems however, in that the heavier springs tend to chip olf the conductive coating. When the coating is chipped away enough contact may permanently be lost, resulting in an inoperative tube.

Plural identical contacts have also been used, spaced around the frame, but this approach has proven unacceptable since it increases the cost and does not solve the problem.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore, an object of this invention to obviate the disadvantages of the prior art.

It is another object of the invention to enhance the operation of color cathode ray tubes.

It is a further object of the invention to improve the high voltage to shadow mask frame electrical connections in color cathode ray tubes.

These objects are accomplished in one aspect of the invention by the provision, in a color cathode ray tube of means for providing a direct electrical path from the high voltage lead to the frame. The means comprises a metallic, electrical conductive ribbon aflixed at one end to the high voltage lead and at its other end being formed to provide an electrical path to the frame.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a color cathode ray tube illustrating an embodiment of the invention;

FIG. 2 is a sectional view illustrating an alternate embodiment of the invention; and

FIG. 3 is a view of the embodiment of FIG. 2 taken along the line 33 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention,

together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above-described drawings. Referring now to the invention with greater particularity, there is shown in FIG. 1 a diagrammatic sectional view of a type of cathode ray tube 10 utilized for the reproduction of polychrome images, as in color television receivers. The tube 10 has an eletrically insulating funnel-shaped body 12, as of glass, with a dish-shaped face panel 14 also of glass sealing the wide end thereof and a cylindrical neck 16 sealing the narrow end. A glass frit is generally utilized to form the panel to body seal designated in the drawings as 17.

A cathodoluminescent screen 18 is formed on the interior surface of face panel 14 and comprises a patterned array of different colored light emitting phosphors. An electron source 20, which may comprise one or more electron guns, is positioned in the neck 16.

To aid in color selection there is provided adjacent the screen a shadow mask assembly 22 which comprises a foraminated portion 24 supported at its peripheral edge 26 by a relatively rigid frame 28. The assembly 22 is sup ported within the face panel 14 by means of cooperation between a plurality of springs 30 (only one of which is shown) mounted on a wall of the frame 28 and a like number of studs 32 mounted on a well 34 of the face panel 14.

During operation of the tube various potentials are applied to electrodes of the guns by means of lead pins which extend through the terminus of the neck 16 and which are appropriately connected to the electrodes. This is conventional in the art and the lead pins are not illustrated in the drawings.

The electrical connection to the final anodes of the guns is achieved through a wall of body 12 by means of an electrically conductive, metallic button 36, which is hermetically sealed in the wall, and an electrically conductive coating 38 which is applied to the interior surface of the body and extends into the neck area and to a point closely adjacent the panel seal 17. Metallic snubbers 40 electrically connected to the final anodes 41 also contact the coating 38 to complete the electrical path thereto.

To achieve the electrical connection to the shadow mask frame there is provided means 42 in the form of an electrically conductive metallic ribbon 44 afiixed at one end 46 to the button 36, as by welding, and which has its other end 48 formed to provide an electrical path to the frame. At least portions of ribbon 44 are frit sealed to the inner wall surface of body 12 and to insure continuity of the coating 38 this should be done prior to the application of the coating 38.

The end 48 of ribbon 44 may be formed as a contact spring 50 as shown in Fig. 1 or it may be formed as a broadened area 52 as is shown in FIGS. 2 and'3. When the latter embodiment is utilized one or more conventionally shaped springs 54 attached to the frame contact the broadened area 52; these springs however, may be considerably more powerful than those used heretofore since there is no danger of contact loss because of erosion or chipping away of the coating 38.

Thus it will be seen that there is herein provided new and novel means of providing a direct electrical path for the high voltage to the shadow mask frame of a color cathode ray tube. The various embodiments are extremely rugged and obviate the diadvantages inherent in the prior art structures.

While there have been shown and described what are at present considered the preferred embodiments of the 4 invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention.

I claim:

1. In a color cathode ray tube having a body formed from an electrically insulating material, a cathodoluminescent screen and a shadow mask assembly comprising a foraminated portion and a rigid frame supported adjacent said screen, an electrically conductive coating on the interior of said envelope and an electrically conductive button hermetically sealed in said insulating body, the improvement comprising: means for providing a direct electrical path from said conductive button to said frame, said means comprising a metallic, electrically conductive ribbon beneath said conductive coating and affixed at one end to said button and at its other end having an electrical path to said path.

2. The invention of claim 1 wherein at least the intermediate portion of said ribbon is bonded to the interior surface of said body.

3. The invention of claim 2 wherein said other end of said ribbon is a frame contacting spring.

4. The invention of claim 2 wherein said other end of said ribbon is a broadened area bonded to said interior surface of said body and said electrical path is a contact spring attached at one of its ends to said frame and at the other of its ends to said broadened area.

References Cited UNITED STATES PATENTS 2,820,166 1/1958 Pinotti 31364 2,863,084 12/1958 Arnott et al. 313-64 X 2,950,408 8/1960 Ketchpel 31364 X 2,951,179 8/1960 Evans 31392 3,102,212 8/1963 Schlesinger 313- X 3,404,303 10/1968 Levin 31385 ROY LAKE, Primary Examiner V. LAFRANCHI, Assistant Examiner US. Cl. X.R.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,543,072 Dated November 24, 1970 Inventor) William H. McNeill It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

column 3, line 3 of the specification "well" should read--wa1l-.

Column 4, line 17 of Claim 1 "path" should read--frame yl uu Gomlaaioner 0 Patents