US3890526A

US3890526A - Faceplate mounting structure for cathode ray tube color selection electrode

Info

Publication number: US3890526A
Application number: US428176A
Authority: US
Inventors: Kazimir Palac
Original assignee: Zenith Radio Corp
Current assignee: Zenith Electronics LLC
Priority date: 1973-12-26
Filing date: 1973-12-26
Publication date: 1975-06-17
Anticipated expiration: 1992-06-17
Also published as: GB1500897A; JPS5099072A; CA1022598A

Abstract

This disclosure depicts a color cathode ray tube including a color selection electrode and a suspension device for suspending the electrode adjacent the faceplate of the tube. The disclosure is particularly directed to a low-cost, compact stud comprising part of the suspension device. The novel stud is relatively flat with a cross-section of substanially greater width than thickness. The stud has a forward portion, at least a tip of which having provision for coupling the stud to the color selection electrode.

Description

United States Patent [1 1 Palac June 17, 1975 1 FACEPLATE MOUNTING STRUCTURE FOR CATHODE RAY TUBE COLOR SELECTION ELECTRODE [75] Inventor:

[73] Assignee: Zenith Radio Corporation, Chicago,

Ill.

[22] Filed: Dec. 26, 1973 [21] App]. No.: 428,176

Kazimir Palac, Carpentersville, Ill.

[52 u.s.c1 ..313/40s;313/404 51 Int. c1... HOlj 29/02; HOlj 29/08; 1101 31/20 581 Field ofSearch ..3l3/855, 92 B, 64,402,

[56] References Cited UNITED STATES PATENTS 11/1960 Fyler 313/92 B X 10/1961 Godfrey 313/92 B X 3,497,746 2/1970 Duistermaat et al. 313/85 S 3,700,949 10/1972 Watanabe et al 313/85 S 3,735,179 5/1973 Kaplan 313/92 B Primary Examiner-Robert Segal Attorney, Agent, or Firm-John H. Coult 5 7] ABSTRACT This disclosure depicts a color cathode ray tube including a color selection electrode and a suspension device for suspending the electrode adjacent the faceplate of the tube. The disclosure is particularly directed to a low-cost, compact stud comprising part of the suspension device. The novel stud is relatively flat with a cross-section of substanially greater width than thickness. The stud has a forward portion, at least a tip of which having provision for coupling the stud to the color selection electrode.

4 Claims, 12 Drawing Figures SHEET 4 3 i3 7 \7 4 0 3 6 00 II 000 0 00 0 0 00 oo o 000 o oo o 0 0000 2 oo 0 OO oo oo oo o 00 0000 o 0000 o 000 00 0 PATENTEUJuHWtsvs 3, 99 525 SHEET 3 rllllll/ QIA'IIIIA FACEPLATE MOUNTING STRUCTURE FOR CATHODE RAY TUBE COLOR SELECTION ELECTRODE CROSS REFERENCE TO RELATED APPLICATIONS This application is related to but in no way dependent upon copending applications Ser. No. 395,334, filed Sept. 7, 1973; Ser. No. 424,017, filed Dec. 12, 1973; and Ser. No. 285,985, filed Sept. 5, 1972, all assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates generally to color cathode ray tubes of the type having a color selection electrode, and more particularly to a suspension device for suspending a color selection electrode in a color tube. The invention is especially concerned with an improved stud comprising part of such an electrode suspension device.

It is well known and widely practiced to secure electrode-supporting studs on a color tube envelope by embedding the studs directly in the envelope while the envelope is in a plastic state. Conventional studs of the type adapted to be embedded by a hot sealing operation are manufactured by heading, deep drawing and- /or machining operations and thus are relatively expensive. Further, they occupy a relatively large area on the stud-receiving surface. The latter drawback is not significant in tubes of the type having a front panel with a flange which receives the studs. This invention, however, while having general applicability, is most advantageously applied to a novel color tube having a flangeless faceplate. In this novel color tube, the color selection electrode is preferably supported by studs secured directly to the inner surface of the faceplate on which is deposited the phosphor screen. Thus, since the studs and associated suspension structure occupy a part of the faceplate screen area, it is extremely important that the amount of area occupied be minimized. Conventional studs of the type adapted to be embedded would occupy an undesirably great amount of the faceplate inner surface area.

OBJECTS OF THE INVENTION It is a general object of this invention to provide an improved device for suspending a color selection electrode in a color cathode ray tube.

It is a more particular object of this invention to provide an improved electrode suspension device which includes a low-cost, compact stud adapted to be embedded in the color tube envelope.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood, however, by reference to the following description taken in conjunction with the accompanying drawings, and in which:

FIG. 1 is a fragmentary perspective view of a corner of a color cathode ray tube, showing a color selection electrode for the tube and a suspension device for suspending the electrode adjacent a faceplate of the tube;

FIG. 2 is an exploded view of the electrode suspension device illustrated in FIG. 1;

FIG. 3 is an enlarged, sectioned elevational view of the electrode suspension device shown in FIGS. 1 and FIG. 4 is a perspective view of a color cathode ray tube faceplate, showing four novel studs comprising part of the electrode suspension device shown in FIGS. l-3;

FIG. 5 is an enlarged view showing one of the electrode-supporting studs embedded in a cathode ray tube faceplate;

FIG. 6 is a sectional view taken along lines 6-6 in FIG. 5;

FIG. 7 is a perspective view, somewhat schematic and partially exploded, of a fixture for embedding the studs shown in FIGS. 1-5 in a cathode ray tube faceplate;

FIG. 8 is an enlarged fragmentary view of a studholding chuck comprising part of the FIG. 7 fixture;

FIG. 9 is a sectional view taken along lines 99 in FIG. 8;

FIG. 10 isa sectional view taken along lines 10--l0 in FIG. 8;

FIG. 11 is a'view of a color tube faceplate showing studs according to this invention embedded therein, the studs having a different configuration and being positioned in a different geometry than as shown in FIG. 4; and

FIG. 12 is an enlarged fragmentary view showing one of the studs illustrated in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention is directed to providing an improved device for suspending a generally rectangular color selection electrode on the envelope of a rectangular-type color cathode ray tube. The suspension device of this invention may be used to suspend a color selection electrode in color cathode ray tubes in general which are of the type requiring such an electrode, however it is especially useful for suspending upon the envelope of a color tube a novel, lightweight, flexible shadow mask as described and claimed in the referent copending applications Ser. Nos. 285,985 and 395,334. The suspension devices are spaced around the electrode to define a suspension system; in a preferred embodiment, the system includes four suspension devices, one at each comer of the electrode. The lightweight, flexible mask alluded to above is adapted to be supported at its corners so as to permit it to conform to the contour of a cathode ray tube faceplate adjacent which it is mounted and to have an exact and precise spacing from the faceplate (commonly known as the Q spacing). This mask is described and claimed, per se, in the above-noted copending applications Ser. No. 285,985 and 395,334.

FIGS. 1-3 illustrate a portion of a color cathode ray tube 8 incorporating a system of suspension devices according to this invention, one of which is shown at 10, for suspending a color selection electrode, illustrated as taking the form of a shadow mask 11. The tube 8 is depicted as having an envelope with a novel construction comprising a funnel 12 sealed to a generally rectangular, flangeless faceplate 14.

The mask 11 is illustrated as being of a low-cost, lightweight, frameless, flexible character, being preferably formed integrally from a single sheet of electrically conductive material such as steel, all as described in detail and claimed in the referent copending application Ser. No. 395,344. The mask 11 is illustrated as having a curved central portion 18 which has formed therein a pattern of electron-transmissive apertures 20. The mask 11 includes a stiffening channel 22 surrounding and joined with the central portion 18.

The mask 11 has a skirt 24 of generally constant depth surrounding and joined with the channel 22. The skirt 24 includes a forwardly directed, outwardly flared body portion terminating in a leading edge portion 28. As described in detail in the referent copending application, the configuration of the strengthening channel 22 and of the skirt 24 is such as to enhance the stiffness of the mask and to shield, to the maximum degree possible, the phosphor screen on the inner surface of the faceplate 14 from stray or overscanned electrons emanating from electron guns (not shown) in the neck of the tube 8.

This invention is concerned with the provision of a compact, low-cost suspension device for cornersuspending a color selection electrode, such as a shadow mask 11, adjacent the faceplate portion of a cathode ray tube. The devices represent an improvement on devices described and claimed in the referent copending application Ser. No. 424,017. The mask suspension devices 10 according to this invention each comprise a stud 34 of novel construction, discussed in detail hereinafter, which is embedded (by an operation to be described) at a precise location in the tube envelope.

Each suspension device 10 includes electrodemounted means for retentively engaging the stud 34. In the illustrated preferred embodiment, the electrodemounted means is shown as comprising a rigid bracket 40 externally surrounding and embracing a corner of the mask 11. The bracket 40 is secured at opposite ends 42, 44 to adjoining sides of the mask 11. The electrode-mounted means further includes coupling means supported by the bracket 40 which comprises a discrete spring 45 and a lug 46 (to be described) for engaging a lug-receiving opening 47 in the stud 34.

In the illustrated preferred embodiment, the bracket 40 comprises two edge-bonded strips of metal which have different coefficients of thermal expansion. The bracket 40 deflects, upon heating of the mask 11, to cause the mask 11 to move nearer to the faceplate 14 so as to provide Q-compensation. By selecting strip materials to have a predetermined difference in coefficient of thermal expansion, and by selecting an appropriate length for the

bracket arms

48, 50, a predetermined temperature increase in the electrode will produce an appropriate translation of the mask 11 to effect Q-compensation. That is to say, the mask 11 will be translated nearer to the faceplate 14 a distance effective to maintain registration between the electron beam landings and the phosphor elements constituting the phosphor screen.

In accordance with one aspect of this invention, the spring 45 preferably has a reverse bend defining a first leg 58 which is secured to the bracket 40 and an opposed second leg 60 which carries the lug 46. The leg 58 is bifurcated into two

parts

62, 64 which straddle a lug-passing opening 66 in thebracket 40. As shown with particular clarity in FIGS. 2 and 3, the lug 46 is secured to leg 60 and extends from the out-facing side thereof through the lug-passing opening 66 in the bracket 40 for retentive engagement with the lugreceiving opening 47 in the stud 34 when the mask 11 is operatively mounted in the tube 8.

The suspension device 10, by the novel construction above-described, has the following desirable proper ties. First, the suspension device is extremely compact, owing in large part to the use of the reverse-bent spring 45 which arches inwardly from the bracket 40 and which deflects in the unused space above the flared skirt 24 on the mask 11. Second, the spring 45 is protected against possible damage during handling of the mask. Third, by the disclosed arrangement wherein only the spring-biased lug 46 extends beyond the bracket, the suspension device is highly suited to an automated or semi-automated mask mounting operation. Fourth, by the use of a rigid bracket 40 to which is secured spring 45, economies in the fabrication of the suspension device are achieved, since the bracket 40 can be welded to the mask 11 in a low tolerance attachment operation and the spring 45 subsequently attached precisely to the bracket by a higher tolerance attachment operation. The latter attachment operation (welding for example) is much easier to hold tolerances on than the operation in which the bracket 40 is secured to the mask 11.

To enhance the engagement/disengagement characteristics of the lug 46 and the stud 34, the lug-receiving opening 47 maybe circular, as shown, or may be generally triangular in shape with rounded corners such that the lug 46 makes a three-point engagement with the opening 47. Further to this end, the lug 46 preferably has at least two sections of different taper, the taper increasing toward the distal end of the lug 46. In the illustrated preferred embodiment, two

sections

68, 70 of increasing taper are shown.

As discussed above, due to the need for an extremely compact suspension device when corner mounting is employed, it is desirable that the spring 45, which functions in part to permit disengagement of the lug 46 from the stud 34, require a minimum travel in order to effect the said disengagement. Further, it is necessary in order to preclude excessive vibration of the mask 11 during operation of the tube, and in order to resist excessive mechanical shocks during handling of the tube (which may reach 40 Gs or more), that the suspension devices 10 each exert a predetermined firm loading force on the mask, e.g., in the order of 2.0 pounds. It is desirable, however, that any loading spring employed not be so stiff as to overload the mask when the tube is baked during assembly or when the tube is operating at maximum operating temperatures. It is also desirable that any such loading spring apply a predetermined load to the mask which is relatively constant within a relatively broad tolerance range.

With these objectives and difficulties considered, the spring 45 has the afore-described reverse bent, inwardly arched construction and is preferably prestressed such that the leg 60 exerts a predetermined load on the bracket 40 when the device is not suspending the mask; this load is substantially equal to the desired load imposed on the mask by the spring 45 when the mask is mounted in the tube. Second, prestressing of the spring 45 permits the use of a relatively low rate I spring. The use of a low rate spring which is prestressed has the result that the load which is applied to the mask when mounted in a tube, can be, predetermined with lower required tolerances since the associated force-versus-displacement characteristic thereof is re]- atively shallow. The lower tolerances associated with the relatively low rate spring also imply that the loading of the mask 11 is more constant over a wider range of spring deflections than would be the case if a relatively stiff spring were employed. The lower tolerances permitted by the use of a relatively low rate spring also result in economies in manufacture of the device 32.

This invention is especially directed to the provision of a low-cost, compact stud, as shown at 34, which is adapted to be embedded in the tube envelope by a hot sealing operation. FIG. 4 shows four of the novel studs 34 embedded in the faceplate 14 on the diagonals of the faceplate and oriented perpendicular thereto. FIG. 5 is a close-up elevational view of one of the studs 34 showing in detail the structure of the preferred form of the stud 34. The stud 34, according to this invention, is relatively flat with a cross-section of substantially greater width w than thickness t. The stud 34 is preferably a stamping formed in a stamping operation from sheet metal stock such as 430 titanium stainless steel, or nickel-steel.

The stud 34 has a forward portion 72 at least a tip of which is adapted to be embedded in the faceplate 14, and a rearward portion 74 which contains the lugreceiving opening 47. The opening 47 receives the lug 46 mounted on the distal end of spring 45. In the illustrated embodiment, the forward portion 72 is wider than the rearward portion 74. The transition from the forward portion 72 to the rearward portion 74 comprises a pair of

abrupt shoulders

76, 78. The

shoulders

76, 78 facilitate the embedding of the studs in the faceplate 14, as will become evident hereinafter.

In order to strengthen the stud 34, if necessary, the stud cross-section may be caused to have a transverse curvature. In the illustrated embodiment, shown with particular clarity in FIGS. 5 and 6, the stud 34 includes a lengthwise corrugation 80 which is formed integrally therein during the stud stamping operation.

FIG. 7 schematically depicts a fixture 81 for embedding the studs 34 in the faceplate 14. The FIG. 7 apparatus is illustrated as including a base 82 from which projects three carbon-tipped

support rods

84, 86, 88 for supporting the faceplate 14. Three

alignment posts

90, 92, 94 serve to align the faceplate 14. A pair of clamping

assemblies

96, 98 include spring-biased, carbon-tipped

pistons

100, 102 which urge the faceplate against the alignment posts 9094. The fixture 81 is illustrated as including a platen 104 which supports four substantially identical chuck-

burner assemblies

106, 108, 110, 112. The platen 104 is raised and lowered by means of air cylinders, shown schematically at 114, 116, 118 and 120.

Each of the chuck-burner assemblies 106-l 12 is illustrated as comprising a slide bar 131 which is adjustable along the faceplate diagonal by means of a slot 122 in the platen 104 and a pair of threaded

bolts

124, 126. Each of the chuck-burner assemblies 106112 supports on the outermost end thereof a chuck 130, shown with particular clarity in FIGS. 810. The chuck 130 includes a cavity 132 having a configuration corresponding to that of the stud 34 to be chucked, and a gas manifold comprising a gas passageway 134 leading to an annular combustion chamber 136 surrounding the cavity 132. A gas hose 138 is coupled to the passageway 134 to conduct gas to the combustion chamber 136. The platen 104 is shown elevated above its normal base 82 and associated structures.

In operation, to embed four studs 34 in the faceplate 14, the studs are loaded into the chucks 130 and secured (by means not shown). The gas is ignited in the combustion chamber 136 and the studs are preheated. The platen 104 is then lowered by means of the air cylinders 114-120 into proximity with the faceplate 14 to cause the faceplate 14 to be heated locally until plastic in the regions where the studs 34 are to be embedded. As the platen is lowered, the platen 104 engages the alignment posts -94, thus assuring alignment thereof with respect to the faceplate 14.

When the faceplate 14 has been heated sufficiently, the platen 104 is lowered until the chucks engage the upper surface of the faceplate 14. The chucks 130 thus serve, not only to hold the studs 34 and to act as burners for heating the studs and the faceplate, but also act as depth gauges to precisely predetermine the degree of penetration of the studs 34 into the faceplate 14.

After the studs have been embedded, the burners are shut off and the seal is permitted to cool. When the seal has become sufficiently rigid to support the studs, the platen 104 is withdrawn.

FIGS. 1-10 describe a suspension system in which the studs 34 are located on the diagonals of the faceplate 14 and oriented perpendicular thereto. The novel stud structure of this invention may be employed in other suspension systems for example, suspension systems wherein the studs are located in the vicinity of the corners but oriented parallel to the sides of the faceplate 14', as shown in FIG. 11, with the longitudinal axis 142 of the studs aligned parallel to the axis of the tube. In such a system each stud 140 is embedded in the faceplate 14' at a predetermined angle 0 with respect to the stud-receiving surface of the faceplate, the angle 0 being measured in the plane of the stud (see FIG. 12).

In accordance with an aspect of this invention, a tip edge 144 of the forward portion 146 of a stud 140 is angled with respect to the longitudinal axis 142 of the stud 140 such that when the stud is embedded, the tip edge 144 is substantially parallel to an adjacent portion of the stud-receiving surface 148 of the faceplate. By thus angling the tip edge 144, uniform penetration of the faceplate is achieved. The FIGS. 11-12 stud 140 is different from the FIGS. 1-10 stud in other respects also. The stud 140 is illustrated as having straight sides, rather than having shoulders as shown at 76, 78 on the stud 34. No corrugation or cross-sectional curvature is included, such being unnecessary if the sheet stock employed is sufficiently rigid. In a preferred embodiment successfully tested, the stud was preferably formed of 0.080 nickel-steel stock and was roughly 0.375 inch wide by 0.50 inch long. No corrugation or crosssectional curvature was needed or provided.

The invention is not limited to the particular details of construction of the embodiments depicted and other modifications and applications are contemplated. For example, whereas the suspension device illustrated has been shown as having a particular construction, the novel stud principles depicted can be employed in accordance with this invention to provide studs having other configurations and studs useful in other types of suspension devices. Whereas the FIG. 7 stud embedding apparatus is shown as employing burners for heating the studs, it is a well-known alternative to use RF heating coils to superheat the studs prior to embedment in a cathode ray tube envelope. The FIG. 7 fixture is intended to be schematic only; the particular apparatus and method employed for embedding the studs, per se, constitute no part of this invention. Rather than embedding the studs in a cooled panel by the use of an alignment fixture, as described, the studs may be embedded in the faceplate during the faceplate molding operation. Other changes may be made in the abovedescribed apparatus without departing from the true spirit and scope of the invention herein involved, and it is intended that the subject matter in the above depiction shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A component of a color cathode ray tube ofa type having a color selection electrode which carries electrode suspension elements at a plurality of points spaced around the periphery thereof, comprising:

a flangeless, three-dimensionally curved faceplate having a concave inner surface and a plurality of low-cost, lightweight metal studs embedded at spaced points around the periphery of said faceplate corresponding to the locations of the electrode suspension elements on the color selection electrode for supporting a color selection electrode in precise spaced relationship to said faceplate inner surface, each of said studs being relatively flat with a cross-section of substantially greater width than thickness and having a tip embedded in the envelope and means for making captive engagement with a suspension element on a color selection electrode.

.-2. The apparatus defined by claim 1 wherein said stud is a stamping formed from sheet metal stock.

3. For use in a rectangular-type color cathode ray tube, a system for suspending a generally rectangular color selection electrode on the envelope of the tube at a predetermined precise spacing from a faceplate portion of the envelope, including four electrode suspension devices spaced around the electrode, one at each corner thereof, each device comprising:

a low-cost, lightweight stud embedded in the tube envelope, said stud being relatively flat with a crosssection of substantially greater width than thickness, said stud having a forward portion, at least a tip of which is adapted to be embedded in the envelope, and a rearward portion including coupling "means for coupling the stud to a color selection electrode; and

electrode-mounted means mounted at a corner of the electrode, including spring means and means carried by said spring means for making captive engagement with said coupling means on said stud.

4. The apparatus defined by claim 3 wherein said stud is a stamping formed from sheet metal stock.

Claims

1. A component of a color cathode ray tube of a type having a color selection electrode which carries electrode suspension elements at a plurality of points spaced around the periphery thereof, comprising: a flangeless, three-dimensionally curved faceplate having a concave inner surface and a plurality of low-cost, lightweight metal studs embedded at spaced points around the periphery of said faceplate corresponding to the locations of the electrode suspension elements on the color selection electrode for supporting a color selection electrode in precise spaced relationship to said faceplate inner surface, each of said studs being relatively flat with a cross-section of substantially greater width than thickness and having a tip embedded in the envelope and means for making captive engagement with a suspension element on a color selection electrode.

2. The apparatus defined by claim 1 wherein said stud is a stamping formed from sheet metal stock.

3. For use in a rectangular-type color cathode ray tube, a system for suspending a generally rectangular color selection electrode on the envelope of the tube at a predetermined precise spacing from a faceplate portion of the envelope, including four electrode suspension devices spaced around the electrode, one at each corner thereof, each device comprising: a low-cost, lightweight stud embedded in the tube envelope, said stud being relatively flat with a cross-section of substantially greater width than thickness, said stud having a forward portion, at least a tip of which is adapted to be embedded in the envelope, and a rearward portion including coupling means for coupling the stud to a color selection electrode; and electrode-mounted means mounted at a corner of the electrode, including spring means and means carried by said spring means for making captive engagement with said coupling means on said stud.