US2819182A - Process of aluminizing cathode ray tube screen - Google Patents
Process of aluminizing cathode ray tube screen Download PDFInfo
- Publication number
- US2819182A US2819182A US449795A US44979554A US2819182A US 2819182 A US2819182 A US 2819182A US 449795 A US449795 A US 449795A US 44979554 A US44979554 A US 44979554A US 2819182 A US2819182 A US 2819182A
- Authority
- US
- United States
- Prior art keywords
- lacquer
- cathode ray
- aluminizing
- film
- ray tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims description 12
- 238000005269 aluminizing Methods 0.000 title claims description 10
- 230000008569 process Effects 0.000 title claims description 9
- 239000004922 lacquer Substances 0.000 claims description 52
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 15
- 239000011248 coating agent Substances 0.000 claims description 14
- 238000000576 coating method Methods 0.000 claims description 14
- 239000010409 thin film Substances 0.000 claims description 3
- 239000010408 film Substances 0.000 description 27
- 239000000975 dye Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 9
- 229910052782 aluminium Inorganic materials 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 9
- 229940072049 amyl acetate Drugs 0.000 description 4
- PGMYKACGEOXYJE-UHFFFAOYSA-N anhydrous amyl acetate Natural products CCCCCOC(C)=O PGMYKACGEOXYJE-UHFFFAOYSA-N 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- MNWFXJYAOYHMED-UHFFFAOYSA-M heptanoate Chemical compound CCCCCCC([O-])=O MNWFXJYAOYHMED-UHFFFAOYSA-M 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 2
- DMLAVOWQYNRWNQ-UHFFFAOYSA-N azobenzene Chemical compound C1=CC=CC=C1N=NC1=CC=CC=C1 DMLAVOWQYNRWNQ-UHFFFAOYSA-N 0.000 description 2
- 238000004040 coloring Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- 230000007480 spreading Effects 0.000 description 2
- 238000011179 visual inspection Methods 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 241001674048 Phthiraptera Species 0.000 description 1
- YSMRWXYRXBRSND-UHFFFAOYSA-N TOTP Chemical compound CC1=CC=CC=C1OP(=O)(OC=1C(=CC=CC=1)C)OC1=CC=CC=C1C YSMRWXYRXBRSND-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 230000019612 pigmentation Effects 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 239000001044 red dye Substances 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- -1 that is Substances 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
- H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
- H01J29/18—Luminescent screens
- H01J29/28—Luminescent screens with protective, conductive or reflective layers
Definitions
- This invention relates to the production of cathode ray tubes and, more specifically, to improved methods of fabrication of the picture reproducing screen employed in cathode ray tubes designed for television purposes.
- the art of laying down the aluminized mirror on the back of the phosphor screen is a highly complicated and relatively delicate one. Briefly, it involves laying a thin film of lacquer over the back of the phosphor screen coating in order to provide a smooth surface on which to form the mirror, laying the aluminum film on the lacquer, and then removing the lacquer by balcing so as to leave the aluminum supported directly by the phosphor. It is necessary to utilize the lacquer as an intermediate processing support in this. way so that the aluminum will not be laid directly over the irregular surface of the phosphor crystals, as this would prevent the achievement of the mirror effect desired.
- a further object of applieants invention is the smoothing out of production flow. This results from preventing processing at one time the large numbers of faultily lacquered bulbs which may occasionally occur, occupying the bulk of the production facilities.
- the layer of water is about two inches deep and the water itself thoroughly deionized.
- a small amount of amyl acetate Prior to dispensing the lacquer solution onto the surface of the water, a small amount of amyl acetate is dispensed into the bulb. Floating on top of the water, the amyl acetate performs three functions, namely, saturation of the bulb atmosphere to regulate the lacquer drying rate, lubrication of the water surface so as to facilitate spreading of the lacquer film as it is applied, and minimization of the tendency of the amyl acetate in the lacquer solution to dissociate itself from the lacquer solution and thereby disturb the proper lacquer solution proportions.
- the lacquer solution which is then deposited onto the surface of the water, may comprise a 7% (weight per volume) solution of nitrocellulose in amyl acetate, additional acetate being added to achieve the desired spreadability or spreading characteristic in the lacquer.
- the stretching characteristic of the lacquer is controlled by the addition of a plasticizer such as di-octal p'hthalate, tri-cresyl phosphate, or polyalkalene glycol.
- a plasticizer such as di-octal p'hthalate, tri-cresyl phosphate, or polyalkalene glycol.
- the lacquer solution is allowed to stand on the water surface for about eighteen minutes, it already having spread over the surface of the water, leaving a thin, even film.
- the lacquer assumes a plastic state and
- the cathode ray tube blank is tilted.
- the heretofore floating lacquer film attaches itself to the phosphor screen, starting at one edge of the face of the tube and continuing gradually across the phosphor screen as the water level recedes. During this process, the film in its plastic state is stretched and achieves the smooth surface desired for the aluminizing process.
- the lacquer once the aluminization step has been accomplished, is no longer retained in the bulb, it being baked out by placing the tube in an oven for a suitable period of time.
- the presence ,tile so that it may of lacquer, such as that above described, in a-finished cathode ray tube would be extremely undesirable as gas would be evolved from it and the achievement of the desired degree of vacuum rendered almost impossible.
- the finished film Upon completion of manufacture of the lacquer film, it is desirable, as was indicated above, to inspect, the finished film so as to prevent losing valuable processing time in aluminizing faulty films and so producing faulty mirror structures.
- a dye or pigmentation to the lacquer solution prior to dispensing the lacquer onto the glass bulb, defects in the finished lacquer film may be made readily recognizable.
- the dye used may be any color, although some colors may be more visible than others; and is preferably volabe baked out along with the lacquer during the bakeout operation subsequent to aluminization.
- a red dye of the azobenzene type such as tetrazobenzene-B (beta) -naphthl has been found satisfactory in concentrations of about 0.05% to 0.15%. Concentrations less than 0.05% give too pale a coloration to the lacquer to be of muchvalue, while concentrations of greater than 0.15% willlikely result in an unduly gassy tube. Other lacquer soluble dyes may, of course, be used, within the scope of the invention. With the dye presently employed, it has been found that no traces of the dye remain behind after the bakeout to color the screen undesirably.
- the effect of the added dye material is to render a coloration to the lacquer film which is sutficient to make the film visible and yet which, upon baking out of the film, will not leave behind any trace of undesirable coloring which would adversely affect the color of the cathode ray tube screen.
- the presence of the coloring not only makes the lacquer film visible, but also tends to improve even further the visiblity of flaws such as strings, tears, swirls, or other film defects where the nature of the defect is such as to produce thickening or doubling over of the lacquer film. This, of course, results in a deepening of color of the lacquer at the point of the imperfection, thus rendering it readily visible.
- the method of aluminizing the phosphor screen of a cathode ray tube which includes the steps of applying a volatile lacquer film containing a volatile azobenzene type dye to the screen, aluminizing the surface of said lacquer, and then removing the lacquer and the dye by baking.
- the method of aluminizing the phosphor screen of a cathode ray tube which includes the steps of applying a volatile lacquer film containing tetrazobenzene-B (Beta) -naphthol in concentrations of approximately 0.05 to 0.15% to the screen, applying an aluminum coating to said film, and then substantially removing the lacquer film and dye by baking.
- a volatile lacquer film containing tetrazobenzene-B (Beta) -naphthol in concentrations of approximately 0.05 to 0.15%
Landscapes
- Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
Description
nited States i PROCESS OF ALUMTNIZING CATHODE RAY TUBE SCREEN No Drawing. Application August 13, 1954 Serial No. 449,795
3 Claims. (Cl. .117-.-.33.. 5)
This invention relates to the production of cathode ray tubes and, more specifically, to improved methods of fabrication of the picture reproducing screen employed in cathode ray tubes designed for television purposes.
A recent development in the television picture tube industry has been the use of an aluminized coating applied to the side of the phosphor picture screen normally away from the viewer, in order to produce a mirror reflecting finish for reflecting light, which would otherwise be lost in the tube itself, out toward the viewer. It has been found that such tubes have an improved brightness over tubes which do not employ the reflecting coating and so have enhanced picture contrast with resulting overall improvement in theflpicture presented to the viewer.
The art of laying down the aluminized mirror on the back of the phosphor screen is a highly complicated and relatively delicate one. Briefly, it involves laying a thin film of lacquer over the back of the phosphor screen coating in order to provide a smooth surface on which to form the mirror, laying the aluminum film on the lacquer, and then removing the lacquer by balcing so as to leave the aluminum supported directly by the phosphor. It is necessary to utilize the lacquer as an intermediate processing support in this. way so that the aluminum will not be laid directly over the irregular surface of the phosphor crystals, as this would prevent the achievement of the mirror effect desired.
The above described process of film application and mirror production, when properly carried out, results in black and white or color pictue tubes whose superiority to unaluminized tubes is well recognized. Naturally, the added steps necessary to produce the aluminized coating on the tube result in higher manufacturing costs and higher customer expense. This increase in cost is even further aggravated by various imperfections which occur during the processing. Among the imperfections which may occur is the porduction of faulty lacquer films, that is, lacquer films which contain holes, strings, tears, swirls or other defects. Imperfections such as these may, after aluminization, occasion rejection rates of as high as 25% of tubes in process. Some saving in cost could be made if inspection of the lacquer film for these imperfections could be accomplished prior to aluminization. However, because of the transparent nature of the lacquer and the finely divided texture of the phosphor screen lying below the lacquer, it is extremely difficult and sometimes impossible, even with the best lighting available, to determine by visual inspection whether or not the required satisfactory lacquer film has been produced. In fact, with some tubes it has been impossible to tell by eye whether or not a lacquer film has been applied. As a result, heretofore, the most reliable test of lacquer film perfection has been inspection of the finished aluminum coating.
It is an object of this invention to facilitate the visual inspection of such lacquered screens, thereby preventing wasted production effort on further processing of atent 2,819,182 Patented 7, 1958 lice tubes to which a faulty lacquer coatinghas been applied. It is a further object of'the invent-ion to provide a Way of readily identifying tubes which have-received -a lacquer coating, in order to simplify the --'identification of cathode ray tube blanks at various stages in the processing. Considerable savings in time,- labor -and expense may be made by using only properly lacquered tubes for aluminization, rather than aluminizi-ng them all as was done heretofore. Further, the added steps of marking or otherwise identifying tubes which have been lacquered are eliminated from the manufacturing process.
A further object of applieants invention is the smoothing out of production flow. This results from preventing processing at one time the large numbers of faultily lacquered bulbs which may occasionally occur, occupying the bulk of the production facilities.
As was indicated previously, in orderto form a'sm'ooth mirror surface of aluminum in the cathode ray tube, it, is necessary to deposit a smooth surface behind the phosphor screen on which the aluminum coating -is to be deposited, for if the aluminum were to be deposited directly on the screen, the coating would follow the microscopically rough contour of the phosphor screen and therefore would be of poor reflective quality. "The necessary smooth surface to which the aluminum refiective coating is applied, is, therefore, ordinarily obtained by the application of a lacquer film or coating. Such a coating is ordinarily applied by dispensing a small amount of lacquer solution onto "the surface of a layer of water poured onto the phosphor screen while-the bulb in process is mounted screen downward. The layer of water is about two inches deep and the water itself thoroughly deionized. Prior to dispensing the lacquer solution onto the surface of the water, a small amount of amyl acetate is dispensed into the bulb. Floating on top of the water, the amyl acetate performs three functions, namely, saturation of the bulb atmosphere to regulate the lacquer drying rate, lubrication of the water surface so as to facilitate spreading of the lacquer film as it is applied, and minimization of the tendency of the amyl acetate in the lacquer solution to dissociate itself from the lacquer solution and thereby disturb the proper lacquer solution proportions.
The lacquer solution, which is then deposited onto the surface of the water, may comprise a 7% (weight per volume) solution of nitrocellulose in amyl acetate, additional acetate being added to achieve the desired spreadability or spreading characteristic in the lacquer. The stretching characteristic of the lacquer is controlled by the addition of a plasticizer such as di-octal p'hthalate, tri-cresyl phosphate, or polyalkalene glycol. The various amounts of diiferent ingredients called for are known in the art and need not be expanded upon here as they are not particularly relevant to this invention.
The lacquer solution is allowed to stand on the water surface for about eighteen minutes, it already having spread over the surface of the water, leaving a thin, even film. As the lacquer stands, it assumes a plastic state and When the proper degree of plasticity is achieved, the cathode ray tube blank is tilted. As the tilted bulb is gradually inverted, the heretofore floating lacquer film attaches itself to the phosphor screen, starting at one edge of the face of the tube and continuing gradually across the phosphor screen as the water level recedes. During this process, the film in its plastic state is stretched and achieves the smooth surface desired for the aluminizing process.
It will be understood that the lacquer, once the aluminization step has been accomplished, is no longer retained in the bulb, it being baked out by placing the tube in an oven for a suitable period of time. The presence ,tile so that it may of lacquer, such as that above described, in a-finished cathode ray tube would be extremely undesirable as gas would be evolved from it and the achievement of the desired degree of vacuum rendered almost impossible.
Upon completion of manufacture of the lacquer film, it is desirable, as was indicated above, to inspect, the finished film so as to prevent losing valuable processing time in aluminizing faulty films and so producing faulty mirror structures. I have found that, by the addition of a dye or pigmentation to the lacquer solution prior to dispensing the lacquer onto the glass bulb, defects in the finished lacquer film may be made readily recognizable. The dye used may be any color, although some colors may be more visible than others; and is preferably volabe baked out along with the lacquer during the bakeout operation subsequent to aluminization. A red dye of the azobenzene type such as tetrazobenzene-B (beta) -naphthl has been found satisfactory in concentrations of about 0.05% to 0.15%. Concentrations less than 0.05% give too pale a coloration to the lacquer to be of muchvalue, while concentrations of greater than 0.15% willlikely result in an unduly gassy tube. Other lacquer soluble dyes may, of course, be used, within the scope of the invention. With the dye presently employed, it has been found that no traces of the dye remain behind after the bakeout to color the screen undesirably.
The effect of the added dye material is to render a coloration to the lacquer film which is sutficient to make the film visible and yet which, upon baking out of the film, will not leave behind any trace of undesirable coloring which would adversely affect the color of the cathode ray tube screen. The presence of the coloring not only makes the lacquer film visible, but also tends to improve even further the visiblity of flaws such as strings, tears, swirls, or other film defects where the nature of the defect is such as to produce thickening or doubling over of the lacquer film. This, of course, results in a deepening of color of the lacquer at the point of the imperfection, thus rendering it readily visible.
I claim:
1. The process of aluminizing a cathode ray tube screen which includes the steps of coating the previously applied phosphor screen with a thin film of lacquer hearing a volatile dye, aluminizing the surface of the lacquer and the dye, and removing the lacquer by baking.
2. The method of aluminizing the phosphor screen of a cathode ray tube which includes the steps of applying a volatile lacquer film containing a volatile azobenzene type dye to the screen, aluminizing the surface of said lacquer, and then removing the lacquer and the dye by baking.
3. The method of aluminizing the phosphor screen of a cathode ray tube which includes the steps of applying a volatile lacquer film containing tetrazobenzene-B (Beta) -naphthol in concentrations of approximately 0.05 to 0.15% to the screen, applying an aluminum coating to said film, and then substantially removing the lacquer film and dye by baking.
References Cited in the file of this patent UNITED STATES PATENTS 1,892,871 Crowell Jan. 3, 1933 2,320,842 Arnold et al June 1, 1943 2,597,617 Campbell May 20, 1952 2,616,816 De Gier et a1. Nov. 4, 1952 2,625,493 Sadowsky Ian. 13, 1953
Claims (1)
1. THE PROCESS OF ALUMINIZING A CATHODE RAY TUBE SCREEN WHICH INCLUDES THE STEPS OF COATING THE PREVIOUSLY APPLIED PHOSPHOR SCREEN WITH A THIN FILM OF LACQUER BEARING A VOLATILE DYE, ALUMINIZING THE SURFACE OF THE LACQUER AND THE DYE, AND REMOVING THE LACQUER BY BAKING.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US449795A US2819182A (en) | 1954-08-13 | 1954-08-13 | Process of aluminizing cathode ray tube screen |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US449795A US2819182A (en) | 1954-08-13 | 1954-08-13 | Process of aluminizing cathode ray tube screen |
Publications (1)
Publication Number | Publication Date |
---|---|
US2819182A true US2819182A (en) | 1958-01-07 |
Family
ID=23785515
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US449795A Expired - Lifetime US2819182A (en) | 1954-08-13 | 1954-08-13 | Process of aluminizing cathode ray tube screen |
Country Status (1)
Country | Link |
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US (1) | US2819182A (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1892871A (en) * | 1928-06-21 | 1933-01-03 | Nat Aniline & Chem Co Inc | Color base and composition containing the same |
US2320842A (en) * | 1942-06-29 | 1943-06-01 | Gen Motors Corp | Paint inspection |
US2597617A (en) * | 1946-11-09 | 1952-05-20 | Gen Electric | Method of depositing and impervious metal film on a granular surface |
US2616816A (en) * | 1947-06-27 | 1952-11-04 | Hartford Nat Bank & Trust Co | Process of providing a thin coherent layer to a rough surface in a vessel |
US2625493A (en) * | 1947-04-17 | 1953-01-13 | Rca Corp | Method of manufacturing a reflective fluorescent screen |
-
1954
- 1954-08-13 US US449795A patent/US2819182A/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1892871A (en) * | 1928-06-21 | 1933-01-03 | Nat Aniline & Chem Co Inc | Color base and composition containing the same |
US2320842A (en) * | 1942-06-29 | 1943-06-01 | Gen Motors Corp | Paint inspection |
US2597617A (en) * | 1946-11-09 | 1952-05-20 | Gen Electric | Method of depositing and impervious metal film on a granular surface |
US2625493A (en) * | 1947-04-17 | 1953-01-13 | Rca Corp | Method of manufacturing a reflective fluorescent screen |
US2616816A (en) * | 1947-06-27 | 1952-11-04 | Hartford Nat Bank & Trust Co | Process of providing a thin coherent layer to a rough surface in a vessel |
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