CRT TUBE GTE SYLVANIA A67-260X UNILINE
CRT in-line electron gun assembly: GTE SYLVANIA UNILINE CRT SYSTEM
1. An improvement in a cathode ray tube three-beam in-line bi-potential electron gun assembly having a longitudinal axis therethrough and including electron generating means formed to separately emit each of the respective electron beams of substantially differing current levels, such beams being directed from a center and two side-related guns to selectively impinge a spatially related patterned electron responsive screen, each of said beams emanating from a gun structure formed of a plurality of related electrode members including a control electrode, an initial accelerator, a focusing electrode and a final accelerator positioned and supported by longitudinal insulative members in a sequential manner forward of a rear-oriented cathode member to effect the formation and control of each of said beams, said improvement comprising:
a unitized focusing electrode structure having a forward apertured portion in the form of a planar integrating member wherein three in-line oriented apertures are defined in a common plane spatially related to the apertures of said final accelerator, the forward aperture of the center gun being larger than those of the two side-related guns, said forward apertures being located in a substantially common plane, said focusing structure having a rear aperture arrangement whereat three spatially related apertures are arranged to accommodate each of said beams, the rear apertures of all of said guns being substantially equal in diameter, said rear apertures of said side-related guns being located in a substantially common plane while the aperture of said center gun is in a separate rearward oriented plane parallel thereto;
an arrangement of apertured initial accelerator members positioned in substantially equal spaced relationship with the respective rear apertured portions of said focusing electrode structure, the aperture portions of the side-related accelerators being in a substantially common plane while the center gun accelerator is in a separate rearward oriented plane parallel thereto; and
an arrangement of apertured control electrode members positioned in substantially equal spaced relationship with the respective initial accelerator members, the aperture portions of the side-related control electrodes being in a substantially common plane while the center gun control electrode is in a separate rearward oriented plane parallel thereto.
2. An improvement in a cathode ray tube three-beam in-line bi-potential electron gun assembly according to claim 1 wherein said forward apertured portion of the planar integrating member of said unitized focusing electrode structure has the respective apertures formed therein defined by peripherally in-turned projections whereupon three cylindrical members of said electrode structure are attached in a manner to extend rearward therefrom.
3. The improvement in a cathode ray tube three-beam in-line bi-potential electron gun assembly according to claim 1 wherein said side-related initial accelerator members are substantially planar and are oriented in a substantially planar structure having an annular opening therein to accommodate the placement thereinto of a substantially cup-shaped accelerator member for said center gun.
4. The improvement in a cathode ray tube three-beam in-line bi-potential electron gun assembly according to claim 1 wherein said control electrode members for the side-related electron guns are substantially planar being located in a common structure in a common plane, said control electrode structure having an annular opening therein to accommodate the spaced positioning therein of said center gun initial accelerator member.
5. The improvement in a cathode ray tube three-beam in-line bi-potential electron gun assembly according to claim 1 wherein said control electrodes and said initial accelerators of the respective guns are individual cup-shaped members, said control and accelerator members for the side-related guns being located in common respective planes, and wherein said control and accelerator members of said center gun are located in separate parallel planes to the rear of said similar members of said side-related gun structures.
This application contains matter disclosed but not claimed in two related United States patent applications filed concurrently herewith and assigned to the assignee of the present invention. These related applications are Ser. No. 699,440, and Ser. No. 699,441.
This invention relates to a plural beam cathode ray tube and more particularly to modifications of a multi-beam in-line electron gun structure employed in a color cathode ray tube.
Many of the cathode ray tubes presently utilized in color television display applications are of the type employing a patterned multi-phosphor cathodoluminescent screen interiorly disposed on the viewing panel of the tube envelope wherein an apertured or multi-opening mask is spatially positioned in relation thereto. A plurality of electron beams, emanating from an electron gun assembly positioned within the neck portion of the envelope are directed to converge at and traverse the apertured mask to impinge and luminescently excite the electron responsive phosphors comprising the patterned screen therebeyond. Focusing of the individual electron beams is conventionally achieved by means of discrete electron lensing, such as bipotential focus lensing; such being dependent on the ratio of the focus voltage to the respective accelerating electrode or anode voltage.
The aforementioned cathodoluminescent screen is of the type made up of repetitive patterns formed of individual dots or stripes of red, blue and green-emitting phosphor components. Since these phosphor materials exhibit differences in efficiency, they require excitation by electron beams of different current levels to produce substantially equal light output. Additional differences in excitation current arise because of the non-uniform response of the human eye to various colors. Thus, to produce white light, more beam current is required to excite the green-emitting phosphor than is necessary to excite the respective red and blue color-emitting components. Each of the beams emanates from a separate electron gun comprising the gun assembly. In a conventional assembly the several cooperating electrode components of each gun are substantially dimensionally similar to the respective components of the related guns in the assembly.
The differences of operating intensities of the several electron beam producing guns functioning simultaneous within the tube to provide a desired white, are conventionally expressed in terms of at least two gun current ratios; namely, red to green (R/G) and red to blue (R/B). For example, in a tube having the red, green, and blue electron guns operating simultaneously to provide a desired cathodoluminescent white, a red/green gun ratio of 1.5:1 indicates that an electron beam current of 50 percent greater intensity is required from the red gun than is needed from the green gun to provide the necessary individual brightness levels of the respective red and green-emitting phosphors. Correspondingly, in the same tube, a red/blue gun ratio of 1.6:1 denotes that the red gun must deliver 60 percent more beam current than the blue gun to satisfactorily complete the white field in the simultaneously excited screen. In accordance with the electron-optics properties of electron guns, the diameter of the electron beam becomes larger as the beam current is increased. Thus, the apparent sharpness of the imagery evidenced in the screen of a color cathode ray tube is resolved in accordance with the respective beam diameters impinging the associated phosphor components of the patterned screen. Accordingly, reduced brightness and diminished resolution of imagery is evidenced with beam landings of larger spot size.
It is an object of the invention to reduce and obviate the aforementioned disadvantages evidenced in the prior art. Another object of the invention is to effect structural changes within the electron gun assembly to provide improved resolution of color cathode ray tube imagery with an associated increase of brightness. A further object of the invention is to effect structural gun changes in the assembly to improve resolution of cathode ray tube imagery without requiring an increase in the neck diameter of the envelope.
These and other objects and advantages are achieved in one aspect of the invention wherein there is provided an improvement in the structure of the cathode ray tube plural beam in-line electron gun assembly wherein at least one gun structure of the assembly, having a beam current level differing from that of the other guns therein, is modified to effect a change in the length of the focusing lensing affecting the electron beam traversing therethrough. This structural modification is effected by changing the length of the focusing electrode member in conjunction with the change of diameter of the output portion of the focusing electrode along with a compatible diametrical change of the related acceleration electrode, to provide a modification of the final focusing lensing formed inter-spatially between the focusing and final acceleration electrode members. This modified final lensing provides focusing of the respective beam to a spot size at the screen which is of a dimension substantially equalling the spot sizes of the associated beams having differing beam currents and emanating from the related guns of the assembly. Thus, by these structural modifications there is provided a marked improvement in the total effective resolution and brightness of the display imagery evidenced in the screen of the tube.
FIG. 1 is an illustration of a color cathode ray tube partially sectioned to show the environment wherein the improvement of the invention is oriented;
FIG. 2 is a prior art elevational view of an in-line three-beam cathode ray tube electron gun assembly;
FIG. 3 is a prior art plan view of the gun assembly illustrated in FIG. 2, taken along the line 3--3 thereof, showing the equal diameters of the related gun structures;
FIG. 4 is a sectional view illustrating the improved gun structure of the invention;
FIG. 5 is a plan view of a portion of the improved gun assembly as portrayed in FIG. 4 taken along the line 5--5 thereof, wherein varied gun diameters are shown;
FIG. 6 is a sectional view of another embodiment of the invention; and
FIG. 7 is a plan view of the initial accelerator region of the gun structure shown in FIG. 6 taken along the line 7--7 therein.
For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following specification and appended claims in connection with the aforedescribed drawings.
With reference to the drawings, there is shown in FIG. 1 a partially sectioned multibeam color cathode ray tube 11 having an encompassing envelope comprised of an integration of a neck portion 13, a funnel portion 15 and a face or viewing panel portion 17. A patterned screen 19 including a repetitive plurality of color-emitting phosphor components is disposed on the interior surface of the viewing panel 17. A multi-opening mask member 21 is positioned within the viewing panel, by means not shown, in a manner whereof the multi-opening portion is spatially related to the patterned screen 19. Positionally encompassed within the neck portion 13 of the envelope is a multi-beam in-line electron gun structure 23, such as, for example an assembly structure of three bi-potential guns 26, 28 and 30, having a longitudinal axis 25 therethrough. The guns of this assembly form and direct three separate electron beams 27, 29, 31 to discretely impinge the patterned screen 19. It is within this electron gun assembly 23 that the improvement of the invention resides.
To fully understand the marked significance of the invention, attention is directed to FIGS. 2 and 3 wherein a prior art plural beam in-line gun structure 23' is shown. In a multi-beam structure of this type, each of the respective beams 27, 29 and 31 traverses a substantially longitudinal arrangement of several functionally related electrode members including, as for example, a control electrode 33, and an initial accelerator 35, a focusing electrode 37, and a final accelerator 39 all of which are positioned in a sequential manner forward of a rear-oriented cathode member 41. Terminally positioned on the forward portions of the final accelerators 39, 39' and 39" is a common apertured cup-like member 43 wherein shunts and/or enhancers may be located in accordance with the known state of the art. As shown, this arrangement constitutes a bi-potential electron gun assembly for effecting the formation and control of each of the respective electron beams 27, 29 and 31. These several electrode members comprising each of the individual guns within the assembly 23 are conventionally positioned and held in spaced relationship with respect to one another by a plurality of insulative support rods, which for purposes of clarity are not shown. It is clearly evident that the diameters " e", "f" and " g" of the final focusing and final acceleration electrode members 37 and 39 are substantially equal. Therefore, final focusing lensing, which is formed inter-spatially between the focusing and final acceleration electrodes, is substantially equal for each of the three guns. Since each of the guns forms and directs an individual electron beam in accordance with the respective beam current applied thereto, the focus spot size of beam impingement at the screen will vary in accordance with the beam current applied to the particular gun. Thus, as a result of differing beam currents and resultant differing spot sizes the resolution and brightness of the screen imagery is noticeably impaired.
The invention is an improvement relating to a modified plural beam in-line electron gun assembly as exemplarily illustrated in FIGS. 4 and 5. There is shown in this instance, a gun assembly construction 44 embodying a plurality of bi-potential structures wherein the center or green gun (G) evidences diameters "Gd" of the related final focusing and final acceleration electrodes 47 and 49 which are larger than the diameters "Bd" and "Rd" of the respective blue (B) and red (R) side-related guns. The resultant final focusing lensing (L 2 ) formed inter-spatially between the final focusing and final acceleration electrode members 47 and 49 of the center gun (G) is of an increased diameter and focal length. The lens so formed exhibits reduced spherical aberration and efficiently focuses the beam to a landing spot size at the screen which is desirably reduced in size to substantially equal the spot sizes effected by the respective lensings (L 2 ') and (L 2 ") of the related (B) and (R) side oriented guns. To achieve the increased object focal length for the larger diametered center gun lensing, a longer focusing electrode 47 is required.
Referring particularly to the center gun (G) as shown in FIG. 4, the electron beam 29' emanating from the emissive material 50 of the cathode 51, in passing through the initial focusing lens (L 1 ) inter-spatially located between the control and initial acceleration electrodes 45 and 46, is directionally influenced to a crossover image 55 effected slightly within the initial accelerating electrode 46. This image or beam size is directly related to the amount of beam current applied to the gun. It is this spot size that is magnified and ultimately imaged on the screen 19 by the final focusing lensing (L 2 ). In similar manner, each of the side-related guns (B) and (R) has a respective beam crossover or image point 55' and 55" at approximately similar locations within its respective initial acceleration electrode 46' and 46". These images are likewise magnified and focused through their respective final focusing lensings (L 2 ') and (L 2 ") to impinge upon the screen.
In accordance with the invention, the diametrical dimensionings of the final focusing lensings (L 2 ') (L 2 ) and (L 2 ") affecting the respective electron beams 27', 29' and 31' are determined by the available planar space in the gun assembly 44 and the differing beam currents supplied to the respective (B), (G) and (R) guns. While it is possible to design each gun to have a final focusing lens of a diameter in keeping with the particular beam current applied thereto, it is most expeditious, from a constructional consideration, to provide each of the side related guns with compromised lensing. For example, a tube having a gun structure, such as is shown in FIG. 4, may have a screen responsive to the following exemplary beam currents.
|(R) red gun = 181 ua or 23% of total current (G) green gun = 346 ua or 43% of total current (B) blue gun = 273 ua or 34% of total current 800 ua Total for 9300° K white|
Averaging the red (R) and blue (B) beam currents effects a compromise percentage in the order of 28.5%.
Referring to FIG. 5, the gun structure within the encompassing neck 13 of the envelope presents the usable planar dimension (D) wherein the three gun openings must be contained. These defined diametrical openings for the blue, green and red guns respectively are denoted as Bd, Gd, and Rd, and such are indicated as apertures in the planar integrating member 59 of the unitized focusing electrode structure 48. The respective apertures are individually defined by peripherally in-turned projections, such as 60, 61 and 62, whereupon the forward ends of the three cylindrical focusing electrode members 47', 47 and 47" are telescoped and attached in a manner to extend rearward therefrom. The dimensions (a) and (b) are structurally required separation distances between the three guns. Therefore, the usable planar structural dimension (D) of the integrating member, wherein the three guns are oriented, is denoted as: Bd+ Gd+ Rd+ a+ b= D
accordingly, the actual apertured dimensioned area per se, designated as (D') is: D- a- b= D'
thus, the apertured diameters of each of the (B) blue and (R) red guns, as based on beam current percentages, are in the order of:
28.5% of D' = Bd and Rd respectively.
Similarly, the aperture of the center or green gun is in the order of:
43.0% of D' = Gd.
As evidenced in FIG. 4, the focusing electrode structure 48 has a rear aperture arrangement whereat three spatially related apertures 63, 65 and 67 are arranged to accommodate each of the respective beams 27', 29' and 31'; these rear apertures of the respective guns being substantially equal in diameter. It is to be noted that the rear apertures 63 and 67 of the (B) and (R) side related guns are located in a substantially common plane while the aperture 65 of the (G) center gun is in a separate rearward oriented plane parallel thereto. The longer focusing electrode 47 for the (G) center gun is necessitated by the larger diameter thereof to achieve the required focal distance from the beam crossover point 55 to the center (c) of the final focusing lens (L 2 ). Such dimensioning is consummated by known principles of electron optics. Accordingly, the apertured initial accelerator members 46', 46 and 46" are positioned in substantially equal spaced relationship with the respective rear apertured portions 63, 65 and 67 of the focusing electrode structure 48. Thus, the aperture portions of the side related accelerators 46' and 46" are in a substantially common plane while the center gun accelerator 46 is in a separate rearward oriented plane parallel thereto. In keeping therewith, the apertured control electrode members 45', 45 and 45" are positioned in substantially equal spaced relationship with respective initial accelerator members 46', 46 and 46". Thus, the apertured portions of the side related control electrodes 45' and 45" are in a substantially common plane while the center gun electrode 45 is in a separate rearward oriented plane and parallel thereto. In this embodiment, the respective control and associated accelerator members are individual cup-shaped members, all of which are suitably supported by conventional longitudinal insulative support rods, not shown.
Another structural embodiment 71 of the improved electron gun of the invention is shown in FIGS. 6 and 7 wherein the rear plural apertured portion 73 of the unitized focusing electrode 75 evidences a single protruding cup-like portion 77 wherein the aperture 79 for the center gun (G) is defined in a plane rearward and parallel to the plane wherein the apertures 79' and 79" of the side related guns (B) and (R) are oriented. In this embodiment, the unitized side related initial accelerator members 81' and 81" are substantially of planar construction being oriented in a substantially planar structure 82 having circular strengthening ribs 83 encompassing each aperture 85' and 85" thereof. This planar structure has an annular opening 87 therein to accommodate the spatial placement thereinto of a substantially cup-shaped accelerator member 89 for the center gun (G). It has been found most expeditious to separately support the center gun cup-shaped accelerator member 89, as spacing difficulties were encountered when the cup-shaped accelerator was structurally incorporated into the aforementioned planar accelerator construction. Electrical connection is made between the cup-shaped member 89 and the planar accelerator member 82 by at least one strap-like means 91. The side related control electrode member 93' and 93" are unitized in substantially the planar construction 95, such being similar to the construction of the initial accelerator members and oriented in an inverted manner spatially related thereto. Thus, the annular openings 87 and 87' in both the planar accelerator 82 and control electrode 95 unitized structures expeditiously accommodates the spaced positioning therein of the center gun initial accelerator member 89.
Thus, the improvement of the invention provides enhanced resolution of color cathode ray tube imagery with an associated increase in brightness. This improvement is achieved without increasing the neck diameter of the envelope. In keeping with the invention, one or more of the electron guns in a plural beam in-line electron gun assembly has modifications of the respective acceleration and focusing electrode members of the individual guns. Such structural modifications pertain primarily to the diameters of the respective output portions of the focusing electrode members and respective lengths thereof. The aperture diameters of the final acceleration electrodes are modified to be in keeping with the respective dimensionings of the associated focusing electrodes. The structurally affected dimensionings are directly relatable to the different levels of beam current assigned to the respective guns. Thus, final focusing lenses of substantially unequal diameters may be provided for the respective beams to effect beam landings of substantially balanced spot sizes at the screen.
While there has been shown and described what are at present considered the preferred embodiments of the 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 as defined by the appended claims.
Magnet retaining means for a CRT beam adjustment device: NECK PURITY MEGNETS description theory.
Improved means are provided for retaining magnets in an electron beam adjustment device formed for external positioning on the neck of a cathode ray tube. The device is comprised of at least one rotatable body member having a plurality of open-top pockets formed therein to accommodate compatibly shaped magnets. The body material adjacent to the pockets has at least one cavity formed therein adjacent to a pocket. Both the cavity and the associated pocket have a common discrete portion of sidewall wherefrom a substantially resilient protuberance is formed to extend into the pocket to provide compressive snap-in means for securely retaining a magnet therein.
1. In an electron beam adjustment device having a plurality of separate magnets retentively inserted therein and formed for positioning on the neck portion of a cathode ray tube having an axis therethrough, magnet retaining means comprising:
2. Magnet retaining means according to claim 1 wherein said cavity is a substantially cylindrical formation having an axis parallel to said aperture axis in said body member.
3. Magnet retaining means according to claim 1 wherein each of said protuberances is a portion of a substantially resilient section of the wall defining the cavity formed in said intervening body material adjacent to said pocket, and wherein said wall section is of a thickness to impart a degree of retentive flexure to the protuberence portion of said pocket sidewall when said magnet member is inserted into said pocket.
4. Magnet retaining means according to claim 1 wherein the respective sidewall defining each of said cavities has at least one gap formed therein in a manner to open through the sidewall of said adjacent pocket, and wherein said cavity is of a size of accommodate a flexure member formed to seat in said cavity, said flexure member having a peripheral portion formed to extend through said sidewall gap into said pocket to provide said resilient protuberance.
5. Magnet retaining means according to claim 1 wherein said cavity extends completely through said body member.
6. Magnet retaining means according to claim 1 wherein said protuberance is a substantially triangular-related arrow head formation vertically oriented relative to said pocket sidewall with the thin apex thereof located proximal to the bottom surface of said pocket.
7. Magnet retaining means according to claim 1 wherein said protuberance is a substantially blister-shaped elongation formed relative to said pocket sidewall with a sloped edge thereof proximal to the bottom surface of said pocket.
8. Magnet retaining means according to claim 1 wherein said body member is formed of a plastic material having a degree of ductility to facilitate the desired flexure of said protuberance.
9. Magnet retaining means according to claim 1 wherein the aperture in said planar body member is substantially coaxial with the axis of said tube.
10. Magnet retaining means according to claim 1 wherein the top surface of said intervening material immediately peripheral to said cavity is provided with a counterbore, and whereof said protuberance has a projecting lip extending into the region of said counterbore.
This invention relates to an external device for controlling electron beams within a cathode ray tube and more particularly to means for retaining magnets in an externally positioned cathode ray tube beam adjustment device.
In a plural beam color cathode ray tube of the type conventionally employed in color television applications, the several electron beams, emitted from electron gun means oriented in the neck portion of the tube, are directed to a patterned cathodoluminescent screen to effect a predetermined display of imagery thereon. For the beams to converge and impinge discrete areas of the screen pattern in the desired manner, it is imperative that the beams be accurately controlled in their travel to the screen. External control of the respective electron beams is augmented by a beam adjustment device formed for positioning on the exterior surface of the neck portion of the tube in the region of the electron gun. For example, one such control means, commonly referenced as a static convergence device, is conventionally comprised of at least one set of insulative ring-like members contiguously related in a manner to be adjustably rotatable on the neck portion of the tube. Each of these members has a plurality of pockets formed therein to accommodate compatibly shaped magnet members which are securely affixed in the respective pockets by a suitable cement-type bonding material that is prone to become a somewhat messy aggravation. This type of bonding fixation, which requires a set-time for adherence, several minutes for instance, has also been found to result in several additional disadvantages. For example in those instances, when due to human error, one or more of the magnets are incorrectly positioned with reference to proper polar orientation, or inserted into the wrong pockets, removal of the magnet to correct the error, either ruins the magnet or the holding member or both. Such mutulation of the holding member also results in the loss of any magnets which have been priorly positioned and affixed therein.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the invention to reduce the aforementioned disadvantages by providing an improved magnet retaining means integrally associated with the body member of the beam adjustment device. Another object is to provide an electron beam adjustment device employing magnet retaining means that enable the individual magnets to be inserted and removed without harm to either the magnet or the device. A further object is to provide an electron beam adjustment device having magnet retaining means therein that provide facile insertion and removal of the magnets as may be desired.
These and other objects and advantages are achieved in one aspect of the invention wherein an electron beam adjustment device, shaped for exterior positioning on the neck portion of a cathode ray tube, is formed of a substantially planar body member having an aperture therein to facilitate slidable encompassment on the neck portion of the tube. A plurality of individual open-top magnet accommodating pockets, each separated from one another by intervening body material, are formed inward as individual recesses from one surface of the body member in substantially radial relationship with the aperture in that member. Each of the pockets has a bottom and a defining sidewall with an opening therein facing into the aperture. At least one cavity is formed in the intervening body material that separates two sequential pockets, in a manner whereof each of the related pockets has a cavity formed adjacent thereto. Each of these cavities has at least one sidewall portion common to a sidewall portion of a related pocket wherefrom a substantially resilient protuberance is formed in a manner to extend from the sidewall of the pocket into the pocket to provide a compressive snap-in means for retaining a compatibly shaped magnet member in the pocket.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exterior view of a color cathode ray tube illustrating the orientation of the electron beam adjustment device on the exterior of the neck portion thereof;
FIG. 2 taken along the line 2--2 of FIG. 1 is a plan view of a planar body member of the beam adjustment device illustrating a plurality of magnet accommodating pockets and retention means for holding the magnets therein;
FIG. 3 is an enlarged partial sectional taken along the line 3--3 of FIG. 2 illustrating details of a pocket and an associated cavity;
FIG. 4 is a partial sectional taken along the line 4--4 of FIG. 2 illustrating a substantially resilient protuberance projecting into the pocket;
FIG. 5 illustrates another embodiment of the pocket related protuberance;
FIG. 6 is a partial plan view showing two magent accommodating pockets and an associated cavity embodiment formed to contain a resilient insert member; and
FIG. 7 is a partial sectional view taken along the line 7--7 of FIG. 6 detailing the cavity with the insert therein.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following specification and appended claims in connection with the aforedescribed drawings.
With reference to the drawings, there is illustrated in FIG. 1, a cathode ray tube 11 of a type commonly employed in color television applications which is shown to have a longitudinal axis 13 therethrough. Such tubes conventionally utilize a plurality of electron beams emanating from electron generating means in either delta or in-line orientation. The paths of the respective beams, which are directed to converge in the region of the screen, are partially controlled by several devices oriented on the exterior of the tube. The image display raster, which is visible in the cathodoluminescent screen disposed on the viewing portion of the face panel 15, is formed by electron beams controlled by magnetic fields effected by the coils of the yoke member 17; such member being positioned upon the tube envelope at substantially the transitional region between the funnel 19 and the neck 21 portions thereof. Positioned rearward thereof on the neck portion of the tube is an exemplary convergence or beam adjustment device 23 containing a plurality of magnetic means arranged to impart a controlling field which is essential to effect the desired shifting of the beams. This beam convergence device 23, which for example is of the type employed to produce static convergence of a substantially in-line arrangement of beams, is comprised of a plurality of substantially planar body members 25, 27, 29, 31, each of which has a similar aperture 33 formed therein of a size to facilitate slidable encompassment of the neck portion 21. The respective body members may be formed of an insulative substance having a degree of ductility such as a thermoplastic material capable of withstanding the regional environmental temperature encountered during tube operation. In operation, each of the members is rotatably adjusted to effect the proper magnetic fields.
In greater detail, each of the body members has a plurality of individual open-top magnet-accommodating pockets formed therein. For clarification, one body member 27 is illustrated in FIGS. 2, 3, and 4 wherein several pockets 35, 36, 37, and 38 are shown, the disposition of which is not intended to be definitive of a particular magnetic arrangement. The exemplary pockets are separated from one another by substantial segments of intervening body material such as denoted by 39, 41, 43, and 45. Each individual pocket is formed inward as a recess from one surface of the body member in substantially radial relationship to the aperture 33, as delineated by r originating from the axis 34 of the aperture. In the structure of the device as shown, the axis of the aperture 34 is substantially coaxial with the axis 15 of the tube 11. The formation of each pocket, for example 37, comprises a bottom 47 and a defining sidewall 49 with an extensive opening 51 therein facing into the related aperture 33. There are cavities such as 53 to 57 formed in the associated substantial segments of intervening body material separating the sequentially related pockets in a manner that each of the related pockets has a cavity formed adjacent thereto. Each cavity is substantially axially parallel with the axis of the aperture in the body member. It is to be noted that the exemplary cavity 57 has a discrete sidewall portion 59 that is common to a sidewall portion 61 of the related pocket 37 wherefrom a protuberance 63 is formed to extend from the sidewall of the pocket into the pocket. The thickness of the this discrete region is such that the interaction of the common wall portions 59-61 imparts a degree of resilience to the protuberance 63 thereby providing a compressive snap-in means for retaining a compatibly shaped magnet member when such is inserted into the pocket. Attention is directed to pocket 36, in FIG. 2, which has a compatibly shaped magnet member 65 compressively retained therein; the related pressure between the magnet and the proturberance effecting a temporary resilient deformation of the common sidewall portion 69. In referring to pocket 38, two adjacent cavities 53 and 54 are related thereto in a manner to provide two opposed protuberances 71 and 72 thereby effecting retentive means for two edges of the magnet member 73. While the cavities are shown to have bottoms, they can be extended as substantially cylindrical openings through the body member, and the term "cavity" is intended to connote a meaning of comparative breadth.
In FIGS. 3 and 4 it is shown that the protuberance 63 does not extend to the bottom of the pocket 47. Rather, the respective protuberance 63 is shaped as a substantially triangular-related arrowhead-formation vertically oriented relative to the pocket sidewall, with the thin apex 75 of the formation being located proximal to the bottom surface 47 of the pocket 37. A protuberance formation of this detailed shaping permits the discrete wall section to impart a gradient of retentive flexure to the protuberance portion 63 of the pocket sidewall when the magnet member is inserted into the pocket.
Another embodiment of the protuberance structure is shown in FIG. 5. In this particular formation, the protuberance 77 is a substantially vertically oriented blister-shaped elongation formed relative to the pocket sidewall 49' with a sloped edge 79 proximal to the bottom surface 47' of the pocket 37' but removed therefrom. A protuberance of this shaping also beneficially utilizes a gradient of retentive resilience provided by the commonly related portion of the sidewall.
As further delineated in FIG. 2, one cavity such as 54 can provide retentive means for two adjacent pockets, i.e., 35 and 38. In this instance, each of the pockets utilizes different or substantially opposed discrete portions 81 and 83 of the cavity sidewall to impart resilience to its respective protuberance.
In referring to FIGS. 6 and 7, another embodiment of the invention is illustrated wherein the cavity 85 is of a size to accommodate a flexure member 87 that is formed to seat in the cavity, the flexure member having a peripheral portion formed to extend or protrude through a sidewall gap 89 into the pocket 91 to provide a resilient protuberance 93. In this embodiment, the body member can be made of a substantially rigid substance, such as glass, ceramic, or hard plastic material; the associated flexure member 87 being formed of rubber or resilient plastic material. The protuberance region of the flexure member forms the discrete wall portion common to both the cavity 85 and the pocket 91.
The static convergence adjustment device 23 is usually comprised of two or more body members 25, 27, 29 and 31 oriented to be rotatably slidable upon one another to provide proper adjustment of the magnetic fields emanating from the magnets therein, whereupon the inter-related adjustment is "locked" by means not shown. Since smooth slidability between contiguous members is essential to achieve fine adjustments, it has been found beneficial to provide a counterbore, collectively referenced as 95, in the top surface of the intervening body material immediately peripheral to the cavities. This counterbore or countersunk region provides a recess into which the lip or tongue 97 of the protuberance can extend without projecting above the plane 99 of the surface of the body member. Thus, there are no projections extending beyond the surface of the body member to hinder slidable rotatable adjustment relative to a contiguous member.
This invention provides improved magnet retaining means that are integrally associated with the respective body members of the beam adjustment device. The improved means for securely retaining the individual magnets facilitates rapid and facile insertion and removal of the magnets without harm to either the magnets or the body member of the device. While the improved magnet retention means has been described in conjunction with a color CRT beam adjustment device, it is not limited thereto as the compressive snap-in means is equally applicable to other types of cathode ray tubes whereof external magnets may be utilized for beam adjustment.
While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.
CRT TUBE GTE SYLVANIA A67-260X Resistive electrical conductive coating for use in a cathode ray tube:
A high resistive electrical conductive coating of discrete composition is provided for band-like deposition in a defined area of the interior surface of substantially the funnel member of a cathode ray tube envelope between the region of the high potential transversal therethrough and the electron generating means oriented in the contiguous neck portion. The coating is an amorphous deposition of a homogeneous mixture of a vitreous substantially insulative frit material admixed with at least one particulate material selected from the group consisting essentially of cadmium oxide, indium oxide and copper oxide wherein the individual particles of the respective oxide ingredients are uniformly dispersed and encapsulated to provide a discretely defined resistive structural means for effecting arc suppression in the region of the electron generating assembly.
1. An improved high resistive electrical conductive composition formulated for application to a defined area of the interior surface of a cathode ray tube envelope during tube fabrication to provide an amorphous deposition thereon, said resistive composition comprising a homogeneous mixture of:
substantially 35 to 65 weight percent of a particulate amorphous type vitreous substantially insulative frit material compatible with said tube environment and having a softening point in the temperature range of substantially 350° C. to 450° C., said frit material being comprised principally of substantially 70 to 85 weight percent of PbO, 5 to 15 weight percent of B2 O3, 2 to 10 weight percent of Al2 O3, and 3 to 5 weight percent of SiO2, said frit material having a particle size averaging within the range of substantially 1.0 to 35.0 microns;
substantially 65 to 35 weight percent of at least one particulate material selected from the group consisting essentially of cadmium oxide, indium oxide and copper oxide homogeneously admixed with said frit, said metal oxide ingredients having a distribution of particles averaging within the range of substantially 1.0 to 10.0 microns in size;
binder solids within the range of substantially 0.1 to 0.5 weight percent; and
solvent means for binder solids, said solvent means being compatible with said tube environment and of a quantity to provide a dispersing medium for said mixture and to impart a viscosity thereto of a value within the range of substantially 150 to 1000 centipoise.2. The improved resistive composition according to claim 1 wherein said amorphous type vitreous frit material exhibits a softening temperature in the order of substantially 370° C. and comprises substantially 35 to 45 weight percent of said composition and wherein said oxide material is present in substantially 65 to 55 weight percent. 3. The improved resistive composition according to claim 1 wherein said amorphous type vitreous frit material exhibits a softening temperature in the order of substantially 440° C. and comprises substantially 50 to 65 weight percent of said composition, and wherein said oxide material is present in substantially 50 to 35 weight percent. 4. The improved resistive composition according to claim 1 wherein said binder solids are in the form of 1% nitrocellulose dissolved in an ester.
A co-pending application Ser. No. 683,647, filed May 6, 1976, now abandoned and assigned to the assignee of the present invention is a division of Ser. No. 600,784 containing matter disclosed but not claimed therein.
BACKGROUND OF THE INVENTION
This invention relates to cathode ray tube construction and more particularly to a high resistive electrical conductive coating employed for suppressing deleterious arcing therein.
The advancement of cathode ray tube technology has resulted in marked improvements in both tube construction and the operational considerations relating thereto, including a trend toward the utilization of higher screen potentials along with the miniaturization and compaction of associated electron gun structures encompassed within the envelope neck portions of smaller diameters. Consequently, spacings between related electrode components in the electron gun structure of the tube have been reduced in keeping with advanced design parameters. The minuteness of these interelectrode spacings, in conjunction with the high voltage differential existant within the tube, and the presence of possible contaminants, increases the probability of dielectric breakdown within the tube structure.
It has been conventional practice in cathode ray tube construction to apply an electrical conductive coating on the interior surface of the funnel member of the tube envelope in a manner to extend from substantially the vicinity of the cathodoluminescent screen into the forward region of the adjoining neck member. This coating, which usually has a high positive electrical potential applied thereto, via connective means traversing the wall of the funnel member, serves as a connective medium conveying a high electrical potential of substantially a common value to both the screen and the terminal electrode of the electron gun assembly oriented within the neck member of the tube envelope. Thus, the condition is present for the possible generation of a spark discharge between the terminal electrode and the adjacent lower voltage electrode in the gun assembly, especially in the presence of aggravating elements such as sublimation deposits, foreign particles, and minute projections extending into the inter-electrode spacings. While considerable effort is expended during tube manufacturing to minimize the factors contributing to dielectric breakdown, the utilization of anode potentials in the order of 30 KV and higher makes the possible presence of contributable arcing conditions factors of extreme importance. Arcing or dielectric breakdown within the cathode ray tube has always been an undesired probability, the magnitude of which has been found to sometimes exhibit destructive intensities of 100 amperes or more. With the increased employment of solid state components in television and allied display devices, arcing within the cathode ray tube can produce catastrophic effects on the vulnerable components in the externally associated operating circuitry. Additionally, an arc discharge initiated within the tube may seriously damage the internal structure thereof and resultantly promote leakage through the sublimation of deleterious metallic deposits on related surfaces in the region of the gun structure.
Cleanliness, precision, vigilance and care in the tube manufacturing process are ever continuing procedures employed to combat the materializing of conditions conductive for arcing. Nevertheless, human factors, processing sublimates, manufacturing tolerances and procedural variations may combine to produce an undesirable and aggravative situation. The discrete use of high resistance coatings on defined interior areas of the funnel member of the envelope has been tried. For example, one such technique is that disclosed by A. V. de Vere Krause in U.S. Pat. No. 2,829,292, wherein a band of resistive coating is internally applied to substantially the juncture region of the funnel and neck members of the tube envelope whereat the snubbers on the terminal electrode of the electron generating assembly make plural-point contact with the high resistance arcing to limit the spark discharge current in the region of the electron gun. However, it has been found in high anode potential tubes that the assembly snubbers tend to effect high resistance point contact with the resistive coating, a condition which is prone to produce intense heat during tube processing when a high voltage conditioning potential of 40 KV or more may be applied to the anode. Such localized heating may cause a buildup of deleterious field emission, ionization and ultimate rupture or checking of the glass wall of the neck member. Additionally, difficulties have been encountered in achieving high resistive electrical conductive coatings that evince uniformity, consistently exhibit the desired electrical characteristics and manifest the necessary tenacious bonding to the surface of the envelope. Since the minimization and eliminating of arcing in present-day color cathode ray tubes is assuming ever increasing importance, it is a prime concern in tube manufacturing to achieve an expedient and consistent coating means for adequately controlling the probable arcing environment within the cathode ray tube per se.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of this invention to reduce and obviate the aforementioned disadvantages that are evidenced in the prior art. Another object of the invention is to provide improved resistive coating means for consistently effecting improved internal arc suppression within a cathode ray tube. It is a further object of the invention to provide improved arc suppression within a cathode ray tube by utilizing an improved and discretely constituted high resistive electrical conductive coating that is capable of being disposed on the wall of the envelope in an expedient and economical manner during tube manufacturing.
These and other objects and advantages are achieved in one aspect of the invention wherein improved arc suppression within a cathode ray tube is achieved by disposing a high resistive electrical conductive coating on a portion of the interior surface of the envelope intermediate a forwardly-oriented first low resistive coating and a rearwardly-oriented second low resistive coating disposed in the neck region forward of the electron generating assembly. The high resistive coating of the invention is comprised of an amorphous deposition of a homogeneous mixture of a vitreous frit material admixed with at least one particulate material selected from the group consisting essentially of cadmium oxide, indium oxide and copper oxide. The frit component of the mixture has a softening point in the range of substantially 350°-450° C. and a coefficient of expansion compatible with the glass composition of the envelope portion upon which the mixture is adhered. The amount of frit material in the deposition is within the range of substantially 35 to 65 percent by weight of the mixture depending upon the frit material utilized wherein the individual particles of the respective oxide or oxides are uniformly dispersed and substantially encapsulated.
BRIEF DESCRIPTION OF THE DRAWINGS
The single FIGURE is a cross-sectional elevation of a cathode ray tube wherein an exemplary embodiment of the improved and discretely constituted high resistive coating of the invention is disposed.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following specification and appended claims in connection with the aforedescribed drawing.
While the invention is applicable for utilization in conventional cathode ray tubes employed in both monochrome and color television application and allied image reproducing systems, for purposes of illustration, a color cathode ray tube utilizing a multi-apertured shadow mask and a plural beam electron generating assembly will be described in this specification.
With particular reference to the drawing, a plural beam color cathode ray tube 11 is illustrated as having an envelope 13 comprised of an integration of neck 15, funnel 17, and viewing panel 19 members; whereof the panel member and the integrated funnel-neck section are hermetically joined by frit sealing during tube fabrication along a congruent sealing region 21 therebetween. A patterned cathodoluminescent screen 23, of diverse color-emitting phosphor areas, is formed on the interior surface of the viewing panel as an array of definitive stripes or dots, in keeping with the known state of the art. A multi-apertured structure 25, in this instance a shadow mask, having openings discretely shaped in keeping with the pattern of the screen, is oriented within the viewing panel by a plurality of locator means 27, in spatial relationship to the patterned screen therein.
An exemplary and partially detailed plural beam electron generating assembly 29 is positioned within the neck member of the envelope and oriented to project a plurality of electron beams in a manner to effect convergence at the apertured mask 25 and thence impinge the patterned screen 23 therebeyond.
It has been conventional practice to dispose electrical conductive coatings on both the interior and exterior surfaces of the funnel member of the tube. These coatings in conjunction with the intervening glass wall of the funnel form a capacitive filtering effect which is utilized in the operational circuitry of the associated television or image display device. The exterior coating 31 on the funnel member is an electrical conductive material, such as Aquadag, and is disposed on a portion of the external surface thereof extending from substantially the region adjacent the panel-funnel seal 21 to approximately the mid-region of the funnel 17.
In the example shown, the interior surface of the funnel member has a tripartite electrical connective-resistive system discretely disposed thereon whereof a first low resistive electrical conductive coating 33, such as an Aquadag composition, is applied in a substantially perimetrical manner on the forward areal portion thereof proximal to the sealing region 21. An electrical potential, for both the screen 23 and the terminal electrode member 35 of the electron generating assembly 29, is applied to this carbonaceous coating composition via a funnel-disposed electrical transversal or connective button 37. Circumferentially contiguous with the rear boundary of the first low resistive coating 33, is a high resistive electrical conductive coating composition 39 of substantially a glass and metal oxide mixture which is uniformly disposed and tenaciously bonded in a substantially perimetrical manner to the interior surface of substantially the rearward portion of the funnel. This high resistive coating is disposed as a skirt-like formation which extends to substantially the neck member 15 whereat it makes contact with a narrow defined band of a second low resistance coating 14 that exhibits scratch resistant characteristics and tight adherence to the glass. This second coating serves as a buss-bar connector providing an area of contact for the multiple contacting elements or snubbers 43 associated with the terminal electrode of the electron generating assembly 29 oriented within the neck member of the envelope.
In a typical electron generating assembly the operational high positive voltage of the anode or terminal electrode 35 may be of a potential in the order of 30 KV or more, applied through the funnel-wall transversal button 37, while the voltage on the adjacent focusing electrode 45 in the assembly 29 is within the range of about 17 to 20 percent of the anode voltage. Thus, it is highly desirable to employ current-limiting and arc-inhibiting coating means within the cathode ray tube envelope.
The tripartite connective-resistive system, provided by the respective electrically related coatings 33, 39 and 41, disposed on the interior surface of the envelope provides an electrical conductive path incorporating a low voltage DC resistance of a value preferably in the multi-megohm range. It has been found that resistance values of this size markedly limit the current and inhibit the initiation of possible deleterious arcing in vulnerable regions. In tubes employing the tripartite combination of coatings as described and shown, the peak arcing currents are significantly reduced to non-destructive magnitude.
In greater detail, the first low resistive conductive coating 33 of the tripartite electrical conductive system is forwardly oriented on the funnel member 17, and may be a conventional carbonaceous coating composition such as Aquadag in conjunction with a water base potassium or sodium silicate binder. This coating is representative of the type commonly disposed on the interior of the funnel and may be applied in a perimetrical manner during funnel preparation by spraying or brushing techniques practiced in the art. While this particular coating may manifest limited scratch resistance, in this instance it is restricted to a region of the funnel whereat there is a minimum risk of accidental abrasion.
The improved high resistive coating 39 of the invention is applied to a discrete area of the funnel as a perimetrical deposition contiguous to and rearward to the first low resistive coating 33, extending therefrom to the neck member 15. This high resistive coating 39 is an amorphous deposition of a homogeneous mixture of a vitreous frit material admixed with at least one particulate material selected from the group consisting essentially of cadmium oxide, indium oxide and copper oxide. Broadly, the frit component exhibits insulative characteristics, a softening point in the range of substantially 350° to 450° C. and a coefficient of expansion compatible with that of the glass composition of the envelope portion to which the deposition is applied. An amorphous vitreous glass is one that retains its glassy structure and does not exhibit devitrification or crystallization during heat transformation. Such glasses applicable to this invention are those, for example, comprised principally of substantially 70 to 85 weight percent PbO, 5 to 15 weight percent B 2 O 3 , 2 to 10 weight percent Al 2 O 3 , and 3 to 5 weight percent SiO 2 . Appropriate examples of suitable frit materials of this type are glass solder frits designated as No. 8463 and No. 7570 respectively, such being commercially available from the Corning Glass Works, Corning, N.Y. These solder glass materials are low melting temperature amorphous vitreous compositions that are completely compatible with the glass of the funnel member. The No. 8463 material is representative of a low melting frit composition having a softening temperature in the order of 370° C.; while the No. 7570 frit is one exhibiting a softening temperature in the order of 440° C. Another exemplary material intermediate to the aforementioned, is one such as frit No. 7555 which has a softening point of substantially 410° C.
An example of the improved current limiting high resistive composition of the invention is achieved by homogeneously admixing one or more of the previously defined particulate oxides, which are inherently electrically conductive, with one of the aforementioned powdered vitreous insulative frit materials. It has been found that the particle sizes of the constituent materials are important in achieving a mixture wherein the particles of, for instance, cadmium oxide are subsequently homogeneously embedded in and substantially encapsulated with glass to provide a resultant tightly-adherent coating exhibiting consistent resistive-conductive characteristics throughout the bulk of the deposition. The particle size distribution of the respective powdered vitreous frit material is within the range of substantially 1.0 to 35.0 microns in size, while the particulate cadmium oxide is of a size distribution within the range of substantially 1.0 to 10.0 microns in size.
An exemplary homogeneous mixture of the particulate components is constituted whereof the No. 7570 vitreous frit material is preferably within the range of substantially 50 to 65 weight percent and the admixed cadmium oxide preferably within the range of substantially 35 to 50 weight percent. The resistive value of the composition can be modified by adjusting the proportions of the frit material and the oxide within the ranges indicated. To effect desired adherence, the amount of the No. 7570 frit material should be at least 50 weight percent of the deposition. For example, a mixture of substantially 60 to 65 weight percent of frit material and substantially 35 to 40 weight percent of cadmium oxide disposed as a 3 to 5 mils finished thickness will provide excellent adherence and an adequate resistance of approximately 2 megohms.
In utilizing the No. 8463 vitreous frit material in the homogeneous mixture, the frit component is preferably within the range of substantially 35 to 45 weight percent and the exemplary cadmium oxide preferably within the range of substantially 55 to 65 weight percent. Modification of the resistive value of the mixture can be achieved by adjusting the proportions of the oxide and frit material within the ranges indicated.
The desired proportions of the respective frit and oxide powdered materials are admixed with a liquid vehicle, compatible with the internal cathode ray tube environment, such as an organic binder which may be a frit lacquer, having exemplary 0.1 to 0.5 weight percent of solids therein, as for example, a solution of 1 percent nitrocellulose dissolved in an ester, such as amyl acetate. This frit-metal-oxide-vehicle combination, being of substantially viscous consistency, is then subjected to a rolling mixing procedure to achieve a homogeneous suspension of the solids therein; whereupon a quantity of diluent preferably having a boiling point higher than that of the lacquer solvent, such as diethyl oxalate, which is compatible with the ester of the organic binder, is admixed to provide the proper viscosity for application and afford adequate drying control. For example, for brush application a viscosity in the order of substantially 300 to 1000 centipoise is appropriate while for spray deposition a viscosity of substantially 150 centipoise is suitable.
The next component of the tripartite system, the second low resistive electrical conductive coating 41 is disposed as a narrow circumferential band in the forward region of the neck member 15 making contact with the rear boundary of the high resistive coating 39. This band is of a width much less than that of the high resistive deposition and provides a buss-bar conductive medium for effecting advantageous connection with the contacting elements 43 terminally oriented on the electron generating assembly 29 whereby undesired high resistance points of contact therebetween are avoided, thusly eliminating harmful localized points of abnormal heating during subsequent high voltage tube processing and conditioning. The band, being less than substantially 1 inch in width, is located in the neck region, whereat it affords contact and spatial association with substantially only the contact elements of the electron generating assembly. The composition of the conductive band is such as to effect a resistance in the order of substantially 500 to 2000 ohms per inch, and for example, may be comprised of a modified conductive carbonaceous material, such as graphite or Aquadag, admixed with a compatible substantially inert fine particulate material, such as ferric oxide, chromic oxide and aluminum oxide, and a suitable aqueous base silicate binder. An exemplary composition suitable for forming a conductive band exhibiting tight adherence a hard scratch-resistant and particle-free surface and the desired conductive properties is one substantially comprised of:
50 weight percent of at least one of the above-mentioned oxide ingredients
30 weight percent of water base Aquadag (30 percent solids)
20 weight percent of water base potassium silicate (35 percent solids)
Such is applied, such as by brushing, to the discrete areal region of the neck as described and shown.
The tripartite connective-resistive system is disposed by a method wherein the first and second low resistive electrical conductive coatings 33 and 41 are suitably applied by conventional means to the respective separated envelope areas as previously described and shown, whereupon they are subjected to drying. The high resistive electrical conductive coating 39 is then applied to the intervening area between the respective first 33 and second 41 coatings in a manner to make contiguous perimetric contact with both coatings, such as an edge-overlap on each. As aforementioned, the first 33 and second 41 conductive coatings utilize aqueous base vehicles, whereas the intermediately disposed high resistive coating 39 employs a chemically diverse but compatible base vehicle to prevent a deleterious edge intermixing of coatings during application.
After drying of the three coatings, a continuous bead of sealing frit 21 is applied to the panel-seal edge of the funnel, whereupon a screen-containing viewing panel is positioned. The panel-funnel assembly is then heated in a conventional manner to approximately 450° C. for a suitable period of time, such as substantially 1 hour, to vitrify the sealing frit and effect jointure between the panel and funnel members. The controlled heat of this sealing procedure additionally produces an amorphous transformation of the homogeneous mixture constituting the high resistive coating 39 and effects degasification of the related first 33 and second 41 conductive coatings comprising the tripartite system. At this stage, an electron generating assembly is inserted into the open neck member and hermetically sealed thereto, whereupon the tube structure is subsequently further processed in the conventional manner.
Thus, there is provided a resistive coating means that effects improved internal arc suppression within a cathode ray tube. The coating means is capable of being discretely disposed on the wall of the envelope in an expedient and economical manner during tube manufacturing.
While there has been shown and described what are at present considered the preferred embodiments of the 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 as defined by the appended claims.
GTE Corporation (formerly General Telephone & Electronics Corporation) was the largest of the "independent" US telephone companies during the days of the Bell System. It acquired the third largest independent, Continental Telephone (ConTel) in 1991. They also owned Automatic Electric, a telephone equipment supplier similar in many ways to Western Electric, and Sylvania Lighting, the only non-communications-oriented company under GTE ownership. GTE provided local telephone service to a large number of areas of the U.S. through operating companies, much like how American Telephone & Telegraph provided local telephone service through its 22 Bell Operating Companies.
The company also acquired BBN Planet, one of the earliest Internet service providers, in 1997. That division became known as GTE Internetworking, and was later spun off into the independent company Genuity (a name recycled from another Internet company GTE acquired in 1997) as part of the GTE-Bell Atlantic merger that created Verizon.
GTE operated in Canada via large interests in subsidiary companies such as BC TEL and Quebec-Téléphone. When foreign ownership restrictions on telecommunications companies were introduced, GTE's ownership was grandfathered. When BC Tel merged with Telus (the name given the privatized Alberta Government Telephones (AGT)) to create BCT.Telus, GTE's Canadian subsidiaries were merged into the new parent, making it the second-largest telecommunications carrier in Canada. As such, GTE's successor, Verizon Communications, was the only foreign telecommunications company with a greater than 20% interest in a Canadian carrier, until Verizon completely divested itself of its shares in 2004.
In the Caribbean, CONTEL purchased several major stakes in the newly independent countries of the British West Indies (Namely in Barbados, Jamaica, and Trinidad and Tobago).
Prior to GTE's merger with Bell Atlantic, GTE also maintained an interactive television service joint-venture called GTE mainStreet (sometimes also called mainStreet USA) as well as an interactive entertainment and video game publishing operation, GTE Interactive Media.
GTE's heritage can be traced to 1918, when three Wisconsin public utility accountants (John F. O'Connell, Sigurd L. Odegard, and John A. Pratt) pooled $33,500 to purchase the Richland Center Telephone Company, serving 1,466 telephones in the dairy belt of southern Wisconsin. In 1920 the three accountants formed a corporation, Commonwealth Telephone Company, with Odegard as president, Pratt as vice-president, and O'Connell as secretary. Richland Center Telephone became part of Commonwealth Telephone, which quickly purchased telephone companies in three nearby communities. In 1922 Pratt resigned as vice-president and was replaced by Clarence R. Brown, a former Bell System employee.
By the mid-1920s Commonwealth had extended beyond Wisconsin borders and purchased the Belvidere Telephone Company in Illinois. It also diversified into other utilities by acquiring two small Wisconsin electrical companies. Expansion was stepped up in 1926, when Odegard secured an option to purchase Associated Telephone Company of Long Beach, California and proceeded to devise a plan for a holding company, to be named Associated Telephone Utilities Company. An aggressive acquisition program was quickly launched in eastern, midwestern, and western states, with the company using its own common stock to complete transactions.
During its first six years, Associated Telephone Utilities acquired 340 telephone companies, which were consolidated into 45 companies operating more than 437,000 telephones in 25 states. By the time the stock market bottomed out in October 1929, Associated Telephone Utilities was operating about 500,000 telephones with revenues approaching $17 million.
In January 1930 a new subsidiary, Associated Telephone Investment Company, was established. Designed to support its parent's acquisition program, the new company's primary business was buying company stock in order to bolster its market value. Within two years the investment company had incurred major losses, and a $1 million loan had to be negotiated. Associated Telephone Investment was dissolved but not before its parent's financial plight had become irreversible, and in 1933 Associated Telephone Utilities went into receivership.
The company was reorganized that same year and resurfaced in 1935 as General Telephone Corporation, operating 12 newly consolidated companies. John Winn, a 26-year veteran of the Bell System, was named president. In 1936 General Telephone created a new subsidiary, General Telephone Directory Company, to publish directories for the parent's entire service area.
Like other businesses, the telephone industry was under government restrictions during World War II, and General Telephone was called upon to increase services at military bases and war-production factories. Following the war, General Telephone reactivated an acquisitions program that had been dormant for more than a decade and purchased 118,000 telephone lines between 1946 and 1950. In 1950 General Telephone purchased its first telephone-equipment manufacturing subsidiary, Leich Electric Company, along with the related Leich Sales Corporation.
By 1951, General Telephone's assets included 15 telephone companies operating in 20 states. In 1955 Theodore Gary & Company, the second-largest independent telephone company, which had 600,000 telephone lines, was merged into General Telephone, which had grown into the largest independent outside the Bell System. The merger gave the company 2.5 million lines. Theodore Gary's assets included telephone operations in the Dominican Republic, British Columbia, and the Philippines, as well as Automatic Electric, the second-largest telephone equipment manufacturer in the U.S. It also had a subsidiary, named the General Telephone and Electric Corporation, formed in 1930 with the Transamerica Corporation and British investors to compete against ITT.
In 1959 General Telephone and Sylvania Electric Products merged, and the parent's name was changed to General Telephone & Electronics Corporation (GT&E). The merger gave Sylvania - a leader in such industries as lighting, television and radio, and chemistry and metallurgy - the needed capital to expand. For General Telephone, the merger meant the added benefit of Sylvania's extensive research and development capabilities in the field of electronics. Power also orchestrated other acquisitions in the late 1950s, including Peninsular Telephone Company in Florida, with 300,000 lines, and Lenkurt Electric Company, Inc., a leading producer of microwave and data transmissions system.
In 1960 the subsidiary GT&E International Incorporated was formed to consolidate manufacturing and marketing activities of Sylvania, Automatic Electric, and Lenkurt, outside the United States. During the early 1960s the scope of GT&E's research, development, and marketing activities was broadened. In 1963 Sylvania began full-scale production of color television picture tubes, and within two years it was supplying color tubes for 18 of the 23 domestic U.S. television manufacturers. About the same time, Automatic Electric began supplying electronic switching equipment for the U.S. defense department's global communications systems, and GT&E International began producing earth-based stations for both foreign and domestic markets. GT&E's telephone subsidiaries, meanwhile, began acquiring community-antenna television systems (CATV) franchises in their operating areas.
In 1964 GT&E president Leslie H. Warner orchestrated a deal that merged Western Utilities Corporation, the nation's second-largest independent telephone company, with 635,000 telephones, into GT&E. The following year Sylvania introduced the revolutionary four-sided flashcube, enhancing its position as the world's largest flashbulb producer. Acquisitions in telephone service continued under Warner during the mid-1960s. Purchases included Quebec Telephone in Canada, Hawaiian Telephone Company, and Northern Ohio Telephone Company and added a total of 622,000 telephone lines to GT&E operations. By 1969 GT&E was serving ten million telephones.
In March 1970 GT&E's New York City headquarters was bombed by a radical antiwar group in protest of the company's participation in defense work. In December of that year the GT&E board agreed to move the company's headquarters to Stamford, Connecticut.
After initially proposing to build separate satellite systems, GT&E and its telecommunications rival, American Telephone & Telegraph, announced in 1974 joint venture plans for the construction and operation of seven earth-based stations interconnected by two satellites. That same year Sylvania acquired name and distribution rights for Philco television and stereo products. GTE International expanded its activities during the same period, acquiring television manufacturers in Canada and Israel and a telephone manufacturer in Germany.
In 1976 newly elected chairman Theodore F. Brophy reorganized the company along five global product lines: communications, lighting, consumer electronics, precision materials, and electrical equipment. GTE International was phased out during the reorganization, and GTE Products Corporation was formed to encompass both domestic and foreign manufacturing and marketing operations. At the same time, GTE Communications Products was formed to oversee operations of Automatic Electric, Lenkurt, Sylvania, and GTE Information Systems. In 1979, another reorganization soon followed under new president Theodore F. Vanderslice. GTE Products Group was eliminated as an organizational unit and GTE Electrical Products, consisting of lighting, precision materials, and electrical equipment, was formed. Vanderslice also revitalized the GT&E Telephone Operating Group in order to develop competitive strategies for anticipated regulatory changes in the telecommunications industry.
In 1979, GTE purchased Telenet to establish a presence in the growing packet switching data communications business. GTE Telenet was later included in the US Telecom joint venture.
GT&E sold its consumer electronics businesses, including the accompanying brand names of Philco and Sylvania in 1980, after watching revenues from television and radio operations decrease precipitously with the success of foreign manufacturers. Following AT&T's 1982 announcement that it would divest 22 telephone operating companies, GT&E made a number of reorganization moves.
In 1982 the company adopted the name GTE Corporation and formed GTE Mobilnet Incorporated to handle the company's entrance into the new cellular telephone business. In 1983 GTE sold its electrical equipment, brokerage information services, and cable television equipment businesses. That same year, Automatic Electric and Lenkurt were combined as GTE Network Systems.
GTE became the third-largest long-distance telephone company in 1983 through the acquisition of Southern Pacific Communications Company. At the same time, Southern Pacific Satellite Company was acquired, and the two firms were renamed GTE Sprint Communications Corporation and GTE Spacenet Corporation, respectively. Through an agreement with the Department of Justice, GTE conceded to keep Sprint Communications separate from its other telephone companies and limit other GTE telephone subsidiaries in certain markets. In December 1983 Vanderslice resigned as president and chief operating officer.
In 1990 GTE reorganized its activities around three business groups: telecommunications products and services, telephone operations, and electrical products. That same year, GTE and Contel Corporation announced merger plans that would strengthen GTE's telecommunications and telephone sectors.
Following action or review by more than 20 governmental bodies, in March 1991 the merger of GTE and Contel was approved. Over half of Contel's $6.6 billion purchase price, $3.9 billion, was assumed debt. In April 1992, James L. "Rocky" Johnson retired after 43 years at GTE, remaining on the GTE board of directors as Chairman Emeritus. Charles "Chuck" Lee was named to succeed Mr. Johnson. Mr. Lee's first order of business was reduction of that obligation. He sold GTE's North American Lighting business to a Siemens affiliate for over $1 billion, shaved off local exchange properties in Idaho, Tennessee, Utah, and West Virginia to generate another $1 billion, divested its interest in Sprint in 1992, and sold its GTE Spacenet satellite operations to General Electric in 1994.
The Telecommunications Act of 1996, promised to encourage competition among local phone providers, long distance services, and cable television companies. Many leading telecoms prepared for the new competitive realities by aligning themselves with entertainment and information providers. GTE, on the other hand, continued to focus on its core operations, seeking to make them as efficient as possible.
Among other goals, GTE's plan sought to double revenues and slash costs by $1 billion per year by focusing on five key areas of operation: technological enhancement of wireline and wireless systems, expansion of data services, global expansion, and diversification into video services. GTE hoped to cross-sell its large base of wireline customers on wireless, data and video services, launching Tele-Go, a user-friendly service that combined cordless and cellular phone features. The company bought broadband spectrum cellular licenses in Atlanta, Seattle, Cincinnati and Denver, and formed a joint venture with SBC Communications to enhance its cellular capabilities in Texas. In 1995, the company undertook a 15-state test of video conferencing services, as well as a video dialtone (VDT) experiment that proposed to offer cable television programming to 900,000 homes by 1997. GTE also formed a video programming and interservices joint venture with Ameritech Corporation, BellSouth Corporation, SBC, and The Walt Disney Company in the fall of 1995.
Foreign efforts included affiliations with phone companies in Argentina, Mexico, Germany, Japan, Canada, the Dominican Republic, Venezuela and China. The early 1990s reorganization included a 37.5 percent workforce reduction, from 177,500 in 1991 to 111,000 by 1994. Lee's fivefold strategy had begun to bear fruit by the mid-1990s. While the communication conglomerate's sales remained rather flat, at about $19.8 billion, from 1992 through 1994, its net income increased by 43.7 percent, from $1.74 billion to a record $2.5 billion, during the same period.
Merger with Bell Atlantic
Bell Atlantic merged with GTE on June 30, 2000, and named the new entity Verizon Communications. The GTE operating companies retained by Verizon are now collectively known as Verizon West division of Verizon (including east coast service territories). The remaining smaller operating companies were sold off or transferred into the remaining ones. Additional properties were sold off within a few years after the merger. On July 1, 2010, Verzion sold many former GTE properties to Frontier Communications.