CA1061193A - Cathode ray tube - Google Patents
Cathode ray tubeInfo
- Publication number
- CA1061193A CA1061193A CA233,171A CA233171A CA1061193A CA 1061193 A CA1061193 A CA 1061193A CA 233171 A CA233171 A CA 233171A CA 1061193 A CA1061193 A CA 1061193A
- Authority
- CA
- Canada
- Prior art keywords
- layer
- display screen
- place
- aluminium layer
- vapour
- 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
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
- H01J9/22—Applying luminescent coatings
- H01J9/227—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
- H01J9/22—Applying luminescent coatings
- H01J9/227—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines
- H01J9/2278—Application of light absorbing material, e.g. between the luminescent areas
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
- Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
Abstract
ABSTRACT:
A method of manufacturing a black aluminium layer on the reflecting aluminium layer which is usually present on the phosphor layer of the display screen of a cathode ray tube. The thickness of the black layer is controlled in that a temperature distribution as a function of the place is provided on the said display screen during the vapour-deposition of the layer in a gas atmosphere.
A method of manufacturing a black aluminium layer on the reflecting aluminium layer which is usually present on the phosphor layer of the display screen of a cathode ray tube. The thickness of the black layer is controlled in that a temperature distribution as a function of the place is provided on the said display screen during the vapour-deposition of the layer in a gas atmosphere.
Description
~L~6~ 3 The invention relates to a method of manufact-uring a cathode ray tube in which a phosphor-containing layer with on top of it a reflecting aluminium layer is provided on a wall portion of the envelope, across which two layers a black aluminium layer is provided by vapour-depositing a quantity of aluminium in a gas atmosphere~
which combination of layers form the display screen on the said wall portion.
The invention also relates to a cathode ray tube manufactured according to said method.
Such a method and cathode-ray tube are known from the United States Patent Specification 3,392,297.
It is known that in a so-called shadow mask tube appro-ximately 80% of the electrons on their way to the display screen are intercepted by an electrode which ensures the colour selection. Said electrode, termed colour selection electrode or shadow mask, which consists of a plate having a very large number of apertures and which is suspended at a short distance in front of the display screen is heated due to the fact that so many electrons impinge upon lt w;th a high energy ( ~ 25 keV). In order to dissipate said thermal energy by radiation as readily as possible, the said electrode is blackened. However, the said colour selection electrode also radiates in the direction of the display screen which for that purpose is also blackened ~ 2 -~6~g3 so as to prevent a reflection of thermal radiation. Said blackening of the display screen is carried out according to the said patent specification by vapour-depositing aluminium in a gas atmosphere (air) of approximately 10 3 Torr (= mm Hg~. However, it is a great drawback that ac~
cording to said known method a black aluminium layer on the reflecting aluminium is obtained which varies consider-ably in thickness as a function of the place on the said display screen. As a result of this, actually, a place-dependence occurs in the transmission of the electrons by the said black layer and the reflecting layer to the phosphor layer so that brightness differences occur in the displayed pictures on the display screen.
It is the object of the invention to control lS a layer thickness of the black alurninium so that a substan-tially uniform layer thickness is obtained throughout the surface of the display screen. If the layer thickness is controlled as a function of the place, a desired thickness variation may also be provided, for example, to compensate for local differences in the transmission of the colour selection electrode.
According to the invention, the method of manufacturing a cathode ray tube of the kind mentioned in the first paragraph is characterized in that the desired thickness variation of the black aluminium layer as a function of the place on the display screen is ob-tained by providing the said wall portion with a place-3L~3 6~L~L~3 dependent temperature distribution during the vapour-deposition of the said black aluminium layer on the reflecting aluminium layer.
The invention is based on the recognition obtained by experiments that it proves possible ~o pro-duce considerable variations in the thickness of said layer with temperature dif~erences of only a ~ew tens bf degrees on the sur~ace to be provided with a Yapour-deposited layer. By deliberately providing a place-depen-dent temperature distribution in the display screen, the vapour-deposition process can be influenced so that a layer is obtained which has substantially everywhere the same thickness or has another desired thickness variation in spite of the large differences in distance from the eua-poration place to the display screen.
The temperature distribution can be provided, for example, by means o~ one or more heating lamps in a given place and according to a given pattern on the side of the display screen where vapour-deposition does not take place. The temperature distribution can moreover be influenced by placing a filter with a place-dependent transmission for thermal radiation.
It is to be noted that it is described in "Zeitschrift fur die angewandte Physik", volume 22, No.
3, 1967, pp. 203-20~ that the direction and value of a particle current in a gas flow depends on the temperature gradient between the place where the material evaporates 10~ 3 and the place where it dPposits. However, reference is made only to comparatively large temperature differences between the evaporation source and the place where the material deposits, while the influence of small temperature differences on said surface is not described at all. Thë
effective use of such temperature differences for, for example, controlling the thickness of the vapour-deposited layer is certainly not considered.
The invention will be described in greater detail with reference to a drawing showing a cathode ray tube manufactured by means of a method according to the invention.
The cathode ray tube shown in the drawing con-sists of an envelope 1 having in/neck 2 means for gene-rating two or more electron beams. Furthermore prese~t in the envelope 1 is a colour selection electrode 3 at a short distance in front of a wall portion of the envelope which forms the display screen 4. The display screen 4 has a phosphor layer 5 across which a reflecting aluminium layer 6 is vapour-deposited in known manner. According to the invention a black aluminium layer 7 is vapour-deposited across said reflect;ng aluminium layer 6. In order to obtain a temperature distribution in the display screen 4, so as to influence and control the thickness of the layer 7 in the already mentioned manner, one or more heat sources, for example infrared lamps, are arranged in front of said display screen in a suitable manner during the vapour-deposition of the black aluminium layer 7.
A temperature distribution in the display screen 4 may also be obta;ned by a local heating or cool-ing with a gas or flow of liquid or another suitable heat-ing or cooling element.
The Table below gives a few results for illus-tration. The distance from the centre to the edge of the display screen is approximately 30 cm. A temperature dis-tribution is provided between the centre and the edge of the display screen as is shown in the first two columns of the Table below. The third column of the Table indi-cates the ratio between the layer thickness of the black aluminium in the centre of the display screen and at the edge.
Temperature Layer thickness ratio centre edge centre/edge 50C 3C 0.66 The Table clearly shows that it is possible with small temperature differences on the display screen to influence the layer thickness considerably. In practice it therefore proves possible to achieve any desired layer thickness distribution.
The vapour-deposition is carried out in a ~ ~63L~ ~3 gas atmosphere in which air of 2 x 10 3 ~ 10 1 Torr can most simply be chosen by causing the pressure, after vapour-depositing the layer 6, to increase to the said value.
~ 7 -
which combination of layers form the display screen on the said wall portion.
The invention also relates to a cathode ray tube manufactured according to said method.
Such a method and cathode-ray tube are known from the United States Patent Specification 3,392,297.
It is known that in a so-called shadow mask tube appro-ximately 80% of the electrons on their way to the display screen are intercepted by an electrode which ensures the colour selection. Said electrode, termed colour selection electrode or shadow mask, which consists of a plate having a very large number of apertures and which is suspended at a short distance in front of the display screen is heated due to the fact that so many electrons impinge upon lt w;th a high energy ( ~ 25 keV). In order to dissipate said thermal energy by radiation as readily as possible, the said electrode is blackened. However, the said colour selection electrode also radiates in the direction of the display screen which for that purpose is also blackened ~ 2 -~6~g3 so as to prevent a reflection of thermal radiation. Said blackening of the display screen is carried out according to the said patent specification by vapour-depositing aluminium in a gas atmosphere (air) of approximately 10 3 Torr (= mm Hg~. However, it is a great drawback that ac~
cording to said known method a black aluminium layer on the reflecting aluminium is obtained which varies consider-ably in thickness as a function of the place on the said display screen. As a result of this, actually, a place-dependence occurs in the transmission of the electrons by the said black layer and the reflecting layer to the phosphor layer so that brightness differences occur in the displayed pictures on the display screen.
It is the object of the invention to control lS a layer thickness of the black alurninium so that a substan-tially uniform layer thickness is obtained throughout the surface of the display screen. If the layer thickness is controlled as a function of the place, a desired thickness variation may also be provided, for example, to compensate for local differences in the transmission of the colour selection electrode.
According to the invention, the method of manufacturing a cathode ray tube of the kind mentioned in the first paragraph is characterized in that the desired thickness variation of the black aluminium layer as a function of the place on the display screen is ob-tained by providing the said wall portion with a place-3L~3 6~L~L~3 dependent temperature distribution during the vapour-deposition of the said black aluminium layer on the reflecting aluminium layer.
The invention is based on the recognition obtained by experiments that it proves possible ~o pro-duce considerable variations in the thickness of said layer with temperature dif~erences of only a ~ew tens bf degrees on the sur~ace to be provided with a Yapour-deposited layer. By deliberately providing a place-depen-dent temperature distribution in the display screen, the vapour-deposition process can be influenced so that a layer is obtained which has substantially everywhere the same thickness or has another desired thickness variation in spite of the large differences in distance from the eua-poration place to the display screen.
The temperature distribution can be provided, for example, by means o~ one or more heating lamps in a given place and according to a given pattern on the side of the display screen where vapour-deposition does not take place. The temperature distribution can moreover be influenced by placing a filter with a place-dependent transmission for thermal radiation.
It is to be noted that it is described in "Zeitschrift fur die angewandte Physik", volume 22, No.
3, 1967, pp. 203-20~ that the direction and value of a particle current in a gas flow depends on the temperature gradient between the place where the material evaporates 10~ 3 and the place where it dPposits. However, reference is made only to comparatively large temperature differences between the evaporation source and the place where the material deposits, while the influence of small temperature differences on said surface is not described at all. Thë
effective use of such temperature differences for, for example, controlling the thickness of the vapour-deposited layer is certainly not considered.
The invention will be described in greater detail with reference to a drawing showing a cathode ray tube manufactured by means of a method according to the invention.
The cathode ray tube shown in the drawing con-sists of an envelope 1 having in/neck 2 means for gene-rating two or more electron beams. Furthermore prese~t in the envelope 1 is a colour selection electrode 3 at a short distance in front of a wall portion of the envelope which forms the display screen 4. The display screen 4 has a phosphor layer 5 across which a reflecting aluminium layer 6 is vapour-deposited in known manner. According to the invention a black aluminium layer 7 is vapour-deposited across said reflect;ng aluminium layer 6. In order to obtain a temperature distribution in the display screen 4, so as to influence and control the thickness of the layer 7 in the already mentioned manner, one or more heat sources, for example infrared lamps, are arranged in front of said display screen in a suitable manner during the vapour-deposition of the black aluminium layer 7.
A temperature distribution in the display screen 4 may also be obta;ned by a local heating or cool-ing with a gas or flow of liquid or another suitable heat-ing or cooling element.
The Table below gives a few results for illus-tration. The distance from the centre to the edge of the display screen is approximately 30 cm. A temperature dis-tribution is provided between the centre and the edge of the display screen as is shown in the first two columns of the Table below. The third column of the Table indi-cates the ratio between the layer thickness of the black aluminium in the centre of the display screen and at the edge.
Temperature Layer thickness ratio centre edge centre/edge 50C 3C 0.66 The Table clearly shows that it is possible with small temperature differences on the display screen to influence the layer thickness considerably. In practice it therefore proves possible to achieve any desired layer thickness distribution.
The vapour-deposition is carried out in a ~ ~63L~ ~3 gas atmosphere in which air of 2 x 10 3 ~ 10 1 Torr can most simply be chosen by causing the pressure, after vapour-depositing the layer 6, to increase to the said value.
~ 7 -
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of manufacturing a cathode ray tube in which a phosphor-containing layer with on top of it a reflecting aluminium layer is provided on a wall portion of the envelope of the tube, across which two layers a black aluminium layer is provided by vapour-depositing a quantity of aluminium in a gas atmosphere, which combina-tion of layers form the display screen on the said wall portion, characterized in that the desired thickness variation of the black aluminium layer as a function of the place on the display screen is obtained by providing the said wall portion with a place-dependent temperature distribution during the vapour-deposition of the said black aluminium layer on the reflecting aluminium layer.
2. A method as claimed in Claim 1, characterized in that the temperature distribution as a function of the place is obtained by one or more heating lamps.
3. A method as claimed in Claim 2, characterized in that a filter having a place-dependent transmission for thermal radiation is arranged between the said heating lamps.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7410762A NL7410762A (en) | 1974-08-12 | 1974-08-12 | METHOD OF MANUFACTURING A CATHODE RAY TUBE AND CATHODE RAY TUBE MADE IN ACCORDANCE WITH THIS PROCESS. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061193A true CA1061193A (en) | 1979-08-28 |
Family
ID=19821894
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA233,171A Expired CA1061193A (en) | 1974-08-12 | 1975-08-07 | Cathode ray tube |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5138863A (en) |
| AT (1) | ATA622075A (en) |
| AU (1) | AU8382675A (en) |
| BE (1) | BE832326A (en) |
| CA (1) | CA1061193A (en) |
| ES (1) | ES440160A1 (en) |
| FR (1) | FR2282160A1 (en) |
| GB (1) | GB1509255A (en) |
| IT (1) | IT1041470B (en) |
| NL (1) | NL7410762A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6224540A (en) * | 1985-07-23 | 1987-02-02 | Mitsubishi Electric Corp | Color picture tube |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4852171A (en) * | 1971-10-29 | 1973-07-21 |
-
1974
- 1974-08-12 NL NL7410762A patent/NL7410762A/en unknown
-
1975
- 1975-08-07 CA CA233,171A patent/CA1061193A/en not_active Expired
- 1975-08-08 IT IT6905775A patent/IT1041470B/en active
- 1975-08-08 GB GB3317975A patent/GB1509255A/en not_active Expired
- 1975-08-09 ES ES440160A patent/ES440160A1/en not_active Expired
- 1975-08-11 AT AT622075A patent/ATA622075A/en not_active Application Discontinuation
- 1975-08-11 BE BE159111A patent/BE832326A/en unknown
- 1975-08-11 AU AU83826/75A patent/AU8382675A/en not_active Expired
- 1975-08-11 JP JP9674375A patent/JPS5138863A/en active Pending
- 1975-08-12 FR FR7525040A patent/FR2282160A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| DE2534133B2 (en) | 1977-03-17 |
| DE2534133A1 (en) | 1976-02-26 |
| AU8382675A (en) | 1977-02-17 |
| FR2282160B1 (en) | 1980-04-30 |
| ES440160A1 (en) | 1977-07-01 |
| IT1041470B (en) | 1980-01-10 |
| GB1509255A (en) | 1978-05-04 |
| NL7410762A (en) | 1976-02-16 |
| JPS5138863A (en) | 1976-03-31 |
| ATA622075A (en) | 1977-03-15 |
| FR2282160A1 (en) | 1976-03-12 |
| BE832326A (en) | 1976-02-11 |
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