US3473065A - Over-scanning shield provided in colored television tube between the mask support and the tube - Google Patents

Description

Oct. 14, 1969 w, scH ET AL.. 3,473,065

OVER-SCANNING- HIELD PROVIDED IN COLORED TELEVISION v TUBE BETWEEN THEMASK SUPPORT AND THE TUBE Filed Jan. 18, 1966 2 Sheets-Sheet 1 lflllllllllwlull Oct. 14, 1969 w w z ET AL 3,473,065 OVER-SCANNING SHIELD PROVIDED IN COLORED TELEVISION TUBE BETWEEN THE MASK SUPPORT AND TEE TUBE Filed Jan. 18, 1966 2 Sheets-Sheet 2 Jim-.5.

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United States Patent OVER-SCANNING SHIELD PROVIDED IN COLORED TELEVISION TUBE BETWEEN THE MASK SUPPORT AND THE TUBE James W. Schwartz, Western Springs, and Daniel J. McCarthy, Glen Ellyn, Ill., assignors to National Video Corporation, Chicago, [1]., a corporation of Illinois Filed Jan. 18, 1966, Ser. No. 521,370 Int. Cl. H013 29/46 U.S. Cl. 313-85 Claims ABSTRACT OF THE DISCLOSURE This invention involves a novel shield against overscanning in a color television tube wherein the shield is formed of a continuous conductive foil having a rolledover edge which is carried by and compressed between the mask support structure and the tube funnel.

This invention relates to color television picture tubes, and more specifically relates to a novel shield structure within the tube to eliminate the adverse effects of overscanning.

It is well known in the color television tube art that a shielding means should be disposed about the inner periphery of the tube adjacent the front plate of the tube to intercept primary and reflected electrons from the side walls of the tube funnel caused by over-scanning of the electron gun. Such electrons if not intercepted will result in spurious excitation of the phosphor coating of the tube face causing undesired white streaks to occur in the color picture.

Shields for this purpose of thin conductive metal have been secured to the interior of the tube and between the mask and funnel by welding. This welding, however, can result in sparks and the possible transfer of copper to the phosphor tube coat. The copper in the phosphor coat will then affect the color response of the coat.

The principle of the present invention is to provide a novel shield against over-scanning in a color television tube wherein the shield is formed of a continuous conductive foil having a rolled-over edge which is carried by and compressed between the mask support structure and tube funnel.

The shield of the present invention will be held securely in place without the necessity of welding and will, at the same time, be an effective barrier and prevent overscanning electrons from affecting the picture.

Accordingly, a primary object of this invention is to eliminate the need for welding of an over-scanning shield to the funnel of a color television tube.

Another object of this invention is to provide a novel continuous foil which has a rolled-over edge which is received solely by the mask support structure of a color television tube with the foil serving as an over-scanning prevention means.

Still another object is to provide a one-piece shield which is sufliciently flexible to fit tightly and securely between the mask frame and glass envelope irrespective of small dimensional changes in the frame and envelope.

These and other objects of this invention will become apparent from the following description when taken in connection with the drawing, in which:

FIGURE 1 is an exploded perspective view of a color television tube which incorporates the shield of the present invention.

FIGURE 2 is a side cross-sectional view showing the glass front plate of FIGURE 1.

FIGURE 3 is a front view of the mask assembly of FIGURE 1.

FIGURE 4 is a top view of FIGURE 3.

FIGURE 5 is a cross-sectional view of FIGURE 3 taken across the lines 5-5 in FIGURE 3.

FIGURE 6- is a front view of the foil shield of the present invention.

FIGURE 7 is a cross-sectional view of FIGURE 6 taken across the lines 7--7 in FIGURE 6, and illustrates the rolled edge of the foil.

FIGURE 8 is a cross-sectional view of the assembled tube incorporating the novel shield of the invention.

FIGURE 9 shows an enlarged cross-sectional view of the manner in which the shield is supported and connected to the funnel along with supplementary contact spring means.

Referring first to FIGURE 1, there is illustrated therein a typical color television tube which comprises a glass funnel 10 which may have an electrically conductive interior, and which receives internally thereof a mask support structure 11 which carries a mask 12 as an integral part thereof.

A shield 13 which is the subject of the present invention is then interposed between mask assembly 11 and the funnel 10, being compressed between the mask frame and the inner conductive surface of the funnel 10.

When the device of FIGURE 1 is assembled, it will be seen that the frame assembly 11 and shield 13 are contained between the interior of the funnel 10 and the glass face plate 14. The narrow end of the funnel will contain suitable electron gun means and focusing means in the usual manner.

The funnel 10 is shown in FIGURES 8 and 9, and is of the standard glass construction with the extending funnel walls with a carbon-containing or other suitable conductive coating shown as coating 10a in FIGURE 9. Face plate 14 is also suitably prepared with the usual coating on the interior thereof, and is provided with a plurality of support buttons 20, 21 and 22 which carry the mask support structure 11, as shown in FIGURE 2.

The mask support structure 11 is best shown in FIG- URES 3, 4 and 5 and is comprised of a generally L- shaped cross-section annular metal member 30 which defines a rectangular opening 31 in the rear thereof. A suitable mask 12 is then directly secured over the outer periphery of the support member 30 as shown. The support member 30 is then provided with a plurality of spring members shown as elements 35, 36 and 37 on the sides thereof which have outwardly extending end portions and which are each suitably connected to the support 30 as by riveting or welding. Springs 35, 36 and 37 of FIG- URES l, 3 and 4 connect to support buttons 20, 21 and 22 of FIGURE 2 in a snap-in type arrangement to secure the mask 12 and mask support frame 11. in position with respect to face plate 14 in the usual manner.

The novel shield of the present invention is best shown in FIGURES 6 and 7 and is shown in position with respect to the assembled components in FIGURES 8 and 9.

Thus, in FIGURES 6 and 7, the shield 13 is constructed of a generally annular metallic foil which may be of aluminum having a thickness which may be of the order of 5 mils.

The shield 13 has a re-entrantly bent outer periphery 40 which extends from a central web 41. A rectangularshaped opening 42 then defines the end of web 41. The web 41 serves as the shielding portion of the shield structure and extends around the outer periphery of the mask 12, in order to effect the desired shielding action. It will be noted that since the web 41 is of a thin foil it can be compressed into shape during the assembly of the tube and maintains itself in a secure position during heating and compression operations of the assembly step.

As further shown in FIGURE 9, the mask frame 11 may also have secured to it a spring 26 which passes through an opening in the foil shield and makes further contact with the conductive interior surface of the funnel.

Although this invention has been described with respect to its preferred embodiment, it should be understood that many variations and modifications thereof will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure hereof, but only by the appended claims.

The embodiments of the invention in which an exclu- ;sive privilege or property is claimed are defined as follows:

1. A shield for shielding against over-scanning in a color television tube; said color television tube comprising a glass funnel, a glass face plate having a generally dished shape connected to said funnel about the largest outer periphery of said funnel, and a mask and frame assembly supported within said dished shape glass face plate; said shield comprising a continuous deformable thin conductive foil having an enlarged opening therethrough to permit passage of an electron beam through the major area of said mask; said shield having a web portion extending from said opening to the outer periphery thereof; said outer periphery of said shield being interposed between adjacent annular surface portions of the mask support frame and the interior of said funnel and being secured therebetween by pressure contact with said adjacent annular surface portions.

2. The device as set forth in claim 1 wherein said outer periphery of said shield comprises a re-entrantly folded section extending substantially at right angles to said web portion.

3. The device of claim 1 wherein said shield outer periphery comprises a rim portion bent substantially perpendicular to said web portion; said web portion having a substantially constant radial length of approximately 1 inch.

4. The device of claim 1 wherein said shield is constructed of metallic foil having a thickness of approximately 5 mils.

5. The device of claim 4 wherein said rim portion comprises a double thickness section of said foil defined by a re-entrant bend of said foil at the outer periphery thereof.

References Cited UNITED STATES PATENTS 2,806,162 9/1957 McQuillen et al 313-85 X 2,806,165 9/1957 Law 313-92 X 2,890,377 6/1959 Fyler 313-92 X 2,897,392 7/1959 Fiore 313-92 2,906,904 9/1959 Woughter et al. 313-85 3,313,975 4/1967 Oess 313-68 X 3,346,753 10/1967 Haas 313-85 X JAMES W. LAWRENCE, Primary Examiner V. LAFRANCHI, Assistant Examiner US. Cl. X.R. 313-313

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