US3825413A

US3825413A - Method of forming sheet glass color tube face panel with pleated skirt

Info

Publication number: US3825413A
Application number: US00226880A
Authority: US
Inventors: J Schwartz
Original assignee: Zenith Radio Corp
Current assignee: Zenith Electronics LLC
Priority date: 1973-02-16
Filing date: 1973-02-16
Publication date: 1974-07-23
Anticipated expiration: 1991-07-23

Abstract

A color television picture tube panel is fabricated of relatively thin sheet glass formed to define a substantially rectangular faceplate area surrounded by an upstanding flange having a fluted configuration over portions of its periphery. The end surface of the flange defines a seal edge for forming a glass-to-glass seal with a funnel having a seal edge of sufficient area to bridge the maximum peak to trough dimensions of the fluted portions. Methods of manufacturing such a panel are also described.

Description

United States Patent 1191 1111 3,825,413 Schwartz July 23, 1974 METHOD OF FORMING SHEET GLASS 2,699,014 1/1955 Steenis 65/107 x COLOR TUBE FACE PANEL WITH 3,381,347 5/1968 Reinwall, Jr. 65/61 X PLEATED SKIRT James W. Schwartz, Glenview, Ill.

Zenith Radio Corporation, Chicago, Ill.

Filed! Feb. 16, 1973 Appl. No.2 226,880

Inventor:

Assignee:

US. Cl 65/61, 65/58, 65/67, 65/107 -Int. Cl C03b 23/02 Field of Search 65/58, 61, 67, 105, 106, 65/107 References Cited UNITED STATES PATENTS 4/1903 Slevert 65/58 Primary Examiner-Arthur D. Kellogg Attorney, Agent, or Firm-Nicholas A. Camasto [5 7 ABSTRACT A color television picture tube panel is fabricated of relatively thin sheet glass formed to define a substantially rectangular faceplate area surrounded by an upstanding flange having a fluted configuration over portions of its periphery. The end surface of the flange defines a seal edge for forming a glass-to-glass seal with a funnel having a seal edge of sufficient area to bridge the maximum peak to trough dimensions of the fluted portions. Methods of manufacturing such a panel are also'described.

4 Claims, 3 Drawing Figures METHOD OF FORMING SHEET GLASS COLOR TUBE FACE PANEL WITH PLEATED SKIRT BACKGROUND OF THE INVENTION This invention relates in general to color television picture tubes and in particular to glass envelopes for color television picture tubes.

The necessity of forming a phosphor mosaic image screen on the inner surface of the picture tube faceplate, which is capable of producing light of three primary colors responsive to selective excitation, dictates utilization of picture tube envelopes which areseparable. The picture tubeenvelope consists of a panel or front section and a funnel or back section. The panel typically has an upstanding flange or skirt, which is useful for strengthening the panel, holding fluids used in screening and manufacturing, providing a seal edge, and for supporting a shadowing electrode in predetermined relationship to the image screen. In conventional tri-gun picture tubes available today, the shadow mask support consists of a plurality of inwardly directed studs embedded in the panel skirt. The shadowing electrode is removable from the mounting studs since, during normal screening operations, it must be inserted and removed a number of times. The need for a separable panel portion, the requirement of supporting a relatively heavy shadowing electrode and the necessity of withstanding high processing temperatures has resulted inthe panel being made .of exceptionally thick glass. As a result,'the glass envelope represents the major cost in manufacturing a color television picture tube. The heavy thick glass panel imposes other restrictions on manufacturing since the various heating cycles must be programmed (in both heating and cooling phases) to preclude excessive stress buildup. In practice, substantial time is required for the gradual heat up and cool down cycles. With a panel of thinner glass, the time required for heating cycles may be reducedand manufacturing economies effected.

SUMMARY OF THE INVENTION In accordance with the invention, the massiveness of the glass panel may be greatly reduced without degradation of its strengthcharacteristics. This is achieved by making the panel with an upstanding partially fluted flange surrounding the faceplate area. The fluted portions are readily formed in the upstanding flange or skirt in a simplified panel manufacturing technique and provide desirable strengthening of the panel member. The resultant panel, while being lighter, retains the requisite resistance to deformation during high processing temperatures encountered in color tube manufacturmg.

The seal edge or mating surface of the panel is formed by grinding or trimming, since it must be relatively flat for frit sealing with the funnel member. The seal edge, however, includes wavelike portions in the panel corners, which requires the seal edge of the funnel to be sufficiently large to bridge the maximum peak to trough dimensions of the flutes.

The fact that a panel configuration including fluted corners may be used in conjunction with an appropriate funnel allows the panel to be fabricated from sheet glass an economical technique not possible with conventionally shaped panels. Consequently, the fluted construction enables manufacturing economiesas well as structural economies. I Accordingly, a principal object of this invention is to provide a panel for a colorcathode ray requiring substantially less material than prior art panels.

A further'object of this invention is .to provide an economical panel for a color cathode raytubecharacterized by fluted portions in the panel skirt.

Another object of this invention is to provide a panel for a color cathode ray tube which is manufactured from sheet glass material formed with fluted strengthening portions in the skirt.

' Other objects and advantages of this invention will become apparent upon reading the following description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a glass envelope including a par- 0 tially cutaway panel section constructed in accordance FIG. 3 represents a partial enlarged view of the nel of FIG. 1 taken along the lines 3-3.

DESCRIPTION or THE PREFERRED EMBODIMENTS fun- ' 12 although such portions need not be restricted to the Spaced behind panel 10 is a funnel portion 16, in-

cludinga large bell-shaped portion 17 and a cylindrical neck portion 18 terminating in a slightly flared portion 19. During a stage of manufacture, an electron gun .assembly will be inserted into neck 18 and sealed therein. In the process, flange 19 will be cut off. Funnel 17 also includes a seal edge 20'for mating engagement with correspondingseal edge 13 of .panel 10. Seal edge 20 is flared in the corners as shown at 21 to accommodate the fluted portions of panel 10. Except that funnel 16 includes flared portions in the corners along the seal edge and that panel 10 is made of thinner glass and has fluted strengthening portions, the tube envelope is similar to those presently in use.

FIG. 2 shows a fluted portion of panel 10 in detail. The seal edge in the fluted portions generally define a sinewave having maximum amplitude at the diagonals of the panel and diminishing with increasing distance away from the diagonals. It is, of course, obvious thatthe glass frit used irn the glass-to-glass sealing step of the final tube manufacture be capable of maintaining the requisite vacuum in the picture tube. Consequently, an enlarged sealing area is provided on the funnel seal edge to embrace the maximum peak to trough dimension of the fluted edge. The critical dimension is that 3 practical size is one that extends over the fullran'ge of excursion of the flutes.

FIG. 3 is anenlarged view of the seal edge of the funnel in one comer with a dashed line representation of fluted portion 12 of the panel superimposed to pictorially show the above relationship of parts. The funnel to panel sealing operation may be readily performed by laying a bead of frit material on the panel seal edge following the fluted configuration. Alternatively, the frit seal may be made by laying a wide bead of frit along the funnel seal edge, the frit'dimension being large enough to surround the fluted glass portion of the panel.

A color tube panel in accordance with the invention lends itself to different techniques of manufacture also. Practically; a sheet of glassmaterial of required thickness may be sagged over a form which defines the interior surface of the desired picture tube panel. As the glass sagsover the rectangular form, fluted portions or folds will develop in the corners. After the requisite degree of cooling, the seal edge is formed, preferably by cutting off unwanted material with a high pressure flame-(The seal edge may also be formed by a grinding operation.) Mounting studs 15 may be inserted either as shown in FIG. 2, by locally softening the glass in the upstanding flange and pushing the studs into position, or by the well-known technique of frittingl It should be understood that the orientation and position of the mounting studs are determined by too] mechanisms (not shown) which are independent of minor irregularities in the upstanding flange.

The panel may also be readily vacuum formed or pressed into the appropriate configuration while in the moldable state. The end result of each of these techniques is an economically manufactured panel of requisite strength but much lighter construction.

The provision of the fluted portions at the comers of the panel is essential to attain sufficient strength, especially to prevent warping of the glass during tube manufacture. In particular, after the mosaic phosphor screen has been deposited using a suitable apertured electrode for photoexposure any distortion of the panel will upset the critical relationship between the aperture mask and the phosphor screen.

For sealing purposes, however, it may be desirable to somewhat compress the fluted portions while still in the moldable state to reduce the maximum peak to trough What has been described is a novel construction for a color television picture tube envelope. It is recognized that numerous modifications and changes in the invention may be made without departing from the invention as set out in the claims.

I claim: I 1'. The method of manufacturing a color television picture tube panel having a seal edge adapted to mate with the seal edge of a picture tube funnel, said method comprising the steps of:

heating a substantially flat piece of glass to its softening temperature; shaping said glass to have an upstanding flange having fluted portions at the corners surrounding a substantially rectangular faceplate area, the maximum peak-to-trough excursions of the flutes con-' stituting said fluted portions being dimensioned to lie within the embrace of the seal edge of the funnel; and

machining said panel to produce a substantially planar seal edge on said upstanding flange.

2. The method of manufacturing a color televison picture tubepanel as set forth in claim 1 further comprising the steps of:

providing a form having a configuration corresponding to that desired for said faceplate area; and sagging the glass over said form to produce said upstanding flange with fluted comers.

3. The method of manufacturing a color television picture tube panel as set forth in claim 1 wherein said upstanding flange is formed by a vacuum forming process.

4. The method of manufacturing a color television picture tube panel as set forth in claim 1 wherein said upstanding flange is formed by pressing said glass into the desired shape.

Claims

1. The method of manufacturing a color television picture tube panel having a seal edge adapted to mate with the seal edge of a picture tube funnel, said method comprising the steps of: heating a substantially flat piece of glass to its softening temperature; shaping said glass to have an upstanding flange having fluted portions at the corners surrounding a substantially rectangular faceplate area, the maximum peak-to-trough excursions of the flutes constituting said fluted portions being dimensioned to lie within the embrace of the seal edge of the funnel; and machining said panel to produce a substantially planar seal edge on said upstanding flange.

2. The method of manufacturing a color televison picture tube panel as set forth in claim 1 further comprising the steps of: providing a form having a configuration corresponding to that desired for said faceplate area; and sagging the glass over said form to produce said upstanding flange with fluted corners.