US2151992A - Wall coating for braun tubes - Google Patents
Wall coating for braun tubes Download PDFInfo
- Publication number
- US2151992A US2151992A US73006A US7300636A US2151992A US 2151992 A US2151992 A US 2151992A US 73006 A US73006 A US 73006A US 7300636 A US7300636 A US 7300636A US 2151992 A US2151992 A US 2151992A
- Authority
- US
- United States
- Prior art keywords
- coating
- wall
- tubes
- wall coating
- layer
- 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
Images
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
- H01J29/86—Vessels; Containers; Vacuum locks
- H01J29/88—Vessels; Containers; Vacuum locks provided with coatings on the walls thereof; Selection of materials for the coatings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2229/00—Details of cathode ray tubes or electron beam tubes
- H01J2229/88—Coatings
- H01J2229/882—Coatings having particular electrical resistive or conductive properties
Definitions
- This invention refers to Braun tubes, and particularly to such tubes in which a conducting coating on the inner wall is desired.
- a conducting coating is customary in many 5 cases, particularly in the flasks of cathode ray and oscillographic tubes, and it is indispensable in high vacuum tubes.
- sufflciently adherent 35 after drying, sufflciently adherent, and dimcult to dissolve.
- binding agents as lacquers, glues, cement type binders, or ceramic fluxes, may be used. If the coating is to resist heat during the baking of the tube, a weak solution of water 40 glass, such as sodium or potassium silicate, is
- a high resistance layer mounted on the inner wall a potential equal to the drop of potential 5 in the vacuum space.
- Known methods, cathode sputtering for example cannot be used, as a rule, for producing such layers of high resistance. If, however, the conductivity of the layer is made lower by the use of a correct ratio of binding 10 agent and carbon, according to this invention, the production of such layers is very simple.
- the production of such a layer may be carried out as follows: The inner wall of the tube is first coated with either the good or poor conducting l5 layer. Then the coating is removed from those places which are to remain uncovered, by mechanical or chemical means. The removal may be accomplished by scraping, washing, or etching, for instance.
- a special heating process should be carried out in order to make the coating more durable, before placing the luminescent screen and the electrode arrangement in the tube, because the vaporizing will produce interfering condensations.
- Layers of sand or whiting may be made for keeping blank those parts of the glass wall which are to remain free of the black layer.
- the black layer may also be subdivided in any desired manner or it may be divided into several parts, having differing resistances, each overlapping or otherwise connected.
- the figure shows an example upon which the resistance coating has been applied as follows:
- the Braun tube envelope shown in the flgure is composed of the usual neck I, in which desired electrodes may be later sealed, widening flask 2, and luminescent screen 3. If, for example, there is a drop of potential of 3,000 volts along the wall between the screen 3 and the starting point of the widening flask, the' i'esistance should be arranged so as to be sma mpared to the internal resistance of the tube, and; accordingly, a magnitude of from one to five megohms will be chosen.
- connection of the resistance may be made by a bordering ring, suchv as a corbon-water glass ring of high conductivity connected to the layer of low conductivity.
- a bordering ring suchv as a corbon-water glass ring of high conductivity connected to the layer of low conductivity.
- One method is to imbed metal parts 0 in the glass wall, or to provide a small glass rod supporting a spiral-shape wire, not shown, and coating metal and glass with the conducting layer.
- This method may be used for any type of Braun or osciilographic tubes, such as those with a photoelectric electrode, and those used for recording or direct showing of television pictures.
- Such wall coatings of high resistance may be manufactured easily and furthermore, will have the advantage of great sturdiness.
- a tube of the cathode ray type comprising an evacuated envelope having a neck portion at one end arranged to receive an electron gun and having a fluorescent screen disposed at the opposite end thereoi, a thin light absorbing coating on said envelope intermediate said neck portion and said screen comprising a mixture including finely divided carbon and an adhesive hinder, the resistance of said mixture varying with the percentage of said adhesive binder, said coating having a predetermined percentage of said adhesive binder therein to determine its resistance, and means for establishing an electrical connection to said coating comprising a metallic element supported by said envelope and a coating of greater conductivity than said first-mentioned coating, in contact with said metallic element and said first-mentioned coating.
Description
March 28, 1939. E. SCHWARTZ WALL COATING FOR BRAUN TUBES Filed April 6, 1936 w V. y W a w LW YW MG ET L M0 C E L N W WD M 0 Am TN 0 L A0 E LC R E H PW m w H INVENTOR. ut/ 5 M15 BY 4% 'M" X? W ATTORNEYS Patented Mar. 28, 1939 COATING FOR BRAUN TUBES I Erich Schwartz, Berlin-Zehlendorf, Germany, assignor to the firm of Fernseh Aktiengesellschaft, Zehlendori' near Berlin, Germany Application April 6, 1936, Serial No. 73,006 In Germany November 30, 1934 1 Claim.
This invention refers to Braun tubes, and particularly to such tubes in which a conducting coating on the inner wall is desired. The use of a conducting coating is customary in many 5 cases, particularly in the flasks of cathode ray and oscillographic tubes, and it is indispensable in high vacuum tubes.
The easiest method of obtaining a mirror-like coating in the flask is to deposit it electrochemically. The main drawback of this method is that the coated flask will then have a high optical reflective power. Fluorescent light, emitted in the backward direction, will be reflected from the coated wall and will produce a general difl5 fused illumination on the fluorescent screen. This results in a decrease of contrast in the tele vision or oscillographic picture. The dark portions of the image particularly, cannot be reproduced according to their true brightness. It is 20 therefore desirable to have a black conducting coating on the inner wall of the flask.
It has been previously proposed to coat the wall of the flask with finely divided (colloidal) carbon in an aqueous solution, such layers being used 25 in the technique of manufacturing vacuum tubes. In the industrial and practical application of this prior method, however, a difliculty is encountered; the coating will be destroyed if deposition of moisture on the inner wall results from a so later glass blowing process or from some other action.
This invention provides a means and method for avoiding this trouble by adding an agent to the carbon solution, which makes the coating,
35 after drying, sufflciently adherent, and dimcult to dissolve. Such binding agents as lacquers, glues, cement type binders, or ceramic fluxes, may be used. If the coating is to resist heat during the baking of the tube, a weak solution of water 40 glass, such as sodium or potassium silicate, is
recommended. Carbon mixed into such a solution will be deposited on the wall, but with an intermediate layer of very thin silicate. However, by a correct application of this method, the
45 over all conductivity of the deposit will still be suiiiciently high, if, for instance, an addition of binder is made, which will also stick sufflciently.
However, in special cases, it may be desirable 50 to produce a wall coating of high resistance, as for instance, in conjunction with a subsequent electron acceleration or for use with acceleration electrical lenses of low refractive power which have a high drop of potential. It is desirable in a both cases to adjust the distribution of the potential along the envelope wall according to the distribution of potential, present or desired, in. the vacuum space. This is done by inducing. in
a high resistance layer mounted on the inner wall, a potential equal to the drop of potential 5 in the vacuum space. Known methods, cathode sputtering for example, cannot be used, as a rule, for producing such layers of high resistance. If, however, the conductivity of the layer is made lower by the use of a correct ratio of binding 10 agent and carbon, according to this invention, the production of such layers is very simple.
The production of such a layer may be carried out as follows: The inner wall of the tube is first coated with either the good or poor conducting l5 layer. Then the coating is removed from those places which are to remain uncovered, by mechanical or chemical means. The removal may be accomplished by scraping, washing, or etching, for instance.
A special heating process should be carried out in order to make the coating more durable, before placing the luminescent screen and the electrode arrangement in the tube, because the vaporizing will produce interfering condensations. Layers of sand or whiting may be made for keeping blank those parts of the glass wall which are to remain free of the black layer.
By a previous coating of certain areas, the black layer may also be subdivided in any desired manner or it may be divided into several parts, having differing resistances, each overlapping or otherwise connected.
The figure shows an example upon which the resistance coating has been applied as follows:
The Braun tube envelope shown in the flgure is composed of the usual neck I, in which desired electrodes may be later sealed, widening flask 2, and luminescent screen 3. If, for example, there is a drop of potential of 3,000 volts along the wall between the screen 3 and the starting point of the widening flask, the' i'esistance should be arranged so as to be sma mpared to the internal resistance of the tube, and; accordingly, a magnitude of from one to five megohms will be chosen.
The connection of the resistance may be made by a bordering ring, suchv as a corbon-water glass ring of high conductivity connected to the layer of low conductivity. These areas, close to the screen 3, shown at 4, and in the neck of the envelope, at 5, are designated in the drawing by appropriate labels.
It is advisable to deposit part of the conductive layer on a rather large metallic surface, in
order to connect it to a metallic lead. One method, for instance, is to imbed metal parts 0 in the glass wall, or to provide a small glass rod supporting a spiral-shape wire, not shown, and coating metal and glass with the conducting layer. This method may be used for any type of Braun or osciilographic tubes, such as those with a photoelectric electrode, and those used for recording or direct showing of television pictures.
Such wall coatings of high resistance may be manufactured easily and furthermore, will have the advantage of great sturdiness.
I claim:
In a tube of the cathode ray type comprising an evacuated envelope having a neck portion at one end arranged to receive an electron gun and having a fluorescent screen disposed at the opposite end thereoi, a thin light absorbing coating on said envelope intermediate said neck portion and said screen comprising a mixture including finely divided carbon and an adhesive hinder, the resistance of said mixture varying with the percentage of said adhesive binder, said coating having a predetermined percentage of said adhesive binder therein to determine its resistance, and means for establishing an electrical connection to said coating comprising a metallic element supported by said envelope and a coating of greater conductivity than said first-mentioned coating, in contact with said metallic element and said first-mentioned coating.
ERICH SCHWARTZ.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2151992X | 1934-11-30 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2151992A true US2151992A (en) | 1939-03-28 |
Family
ID=7987486
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US73006A Expired - Lifetime US2151992A (en) | 1934-11-30 | 1936-04-06 | Wall coating for braun tubes |
Country Status (1)
Country | Link |
---|---|
US (1) | US2151992A (en) |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2545120A (en) * | 1948-02-27 | 1951-03-13 | Rca Corp | Cathode-ray tube arc-over preventive |
US2575383A (en) * | 1946-10-22 | 1951-11-20 | Bell Telephone Labor Inc | High-frequency amplifying device |
US2629838A (en) * | 1949-08-04 | 1953-02-24 | Technicolor Motion Picture | Color television screen with correction for overplay |
US2666864A (en) * | 1950-01-20 | 1954-01-19 | Westinghouse Electric Corp | Image intensifier tube |
US2699510A (en) * | 1951-02-24 | 1955-01-11 | Hartford Nat Bank & Trust Co | Cathode-ray tube |
US2740062A (en) * | 1952-05-27 | 1956-03-27 | Rca Corp | Cathode ray picture tube |
US2820166A (en) * | 1955-05-18 | 1958-01-14 | Owens Illinois Glass Co | Conductive medium for anode button in a cathode ray tube |
US2829292A (en) * | 1955-07-04 | 1958-04-01 | Cinema Television Ltd | Cathode-ray tubes |
US2937314A (en) * | 1959-12-28 | 1960-05-17 | Columbia Broadcasting Syst Inc | High resolution cathode ray tube apparatus |
US3108906A (en) * | 1958-05-24 | 1963-10-29 | Philips Corp | Electric discharge tube |
US3132282A (en) * | 1959-12-14 | 1964-05-05 | Bendix Corp | Two dimensional sweep circuit |
US4052641A (en) * | 1975-03-14 | 1977-10-04 | Corning Glass Works | Electrically conductive coating in cathode ray tube |
US4196227A (en) * | 1978-04-20 | 1980-04-01 | Wagner Electric Corporation | Method of forming carbon anodes in multidigit fluorescent display devices |
-
1936
- 1936-04-06 US US73006A patent/US2151992A/en not_active Expired - Lifetime
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2575383A (en) * | 1946-10-22 | 1951-11-20 | Bell Telephone Labor Inc | High-frequency amplifying device |
US2545120A (en) * | 1948-02-27 | 1951-03-13 | Rca Corp | Cathode-ray tube arc-over preventive |
US2629838A (en) * | 1949-08-04 | 1953-02-24 | Technicolor Motion Picture | Color television screen with correction for overplay |
US2666864A (en) * | 1950-01-20 | 1954-01-19 | Westinghouse Electric Corp | Image intensifier tube |
US2699510A (en) * | 1951-02-24 | 1955-01-11 | Hartford Nat Bank & Trust Co | Cathode-ray tube |
US2740062A (en) * | 1952-05-27 | 1956-03-27 | Rca Corp | Cathode ray picture tube |
US2820166A (en) * | 1955-05-18 | 1958-01-14 | Owens Illinois Glass Co | Conductive medium for anode button in a cathode ray tube |
US2829292A (en) * | 1955-07-04 | 1958-04-01 | Cinema Television Ltd | Cathode-ray tubes |
US3108906A (en) * | 1958-05-24 | 1963-10-29 | Philips Corp | Electric discharge tube |
US3132282A (en) * | 1959-12-14 | 1964-05-05 | Bendix Corp | Two dimensional sweep circuit |
US2937314A (en) * | 1959-12-28 | 1960-05-17 | Columbia Broadcasting Syst Inc | High resolution cathode ray tube apparatus |
US4052641A (en) * | 1975-03-14 | 1977-10-04 | Corning Glass Works | Electrically conductive coating in cathode ray tube |
US4196227A (en) * | 1978-04-20 | 1980-04-01 | Wagner Electric Corporation | Method of forming carbon anodes in multidigit fluorescent display devices |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2151992A (en) | Wall coating for braun tubes | |
US2233786A (en) | Fluorescent screen assembly and method of manufacture | |
US3005731A (en) | Method of applying an electroconductive film to a vitreous surface | |
US2197625A (en) | Cathode ray tube | |
US2029639A (en) | Braun tube | |
US2485561A (en) | Cathode-ray tube | |
US2251992A (en) | Picture transmitter tube | |
US3383244A (en) | Photo-sensitive devices employing photo-conductive coatings | |
US2214973A (en) | Cathode ray tube | |
US3023131A (en) | Method of forming a photo-emissive surface and coated article | |
US2162391A (en) | Electron tube with high ohmic wall coatings | |
US2596617A (en) | Increasing number of holes in apertured metal screens | |
US2833675A (en) | Method of imparting red response to a photoconductive target for a pickup tube | |
US2171970A (en) | Cathode ray tube | |
US2967962A (en) | Television and like camera tubes | |
US2438668A (en) | Cathode-ray tube screen and process | |
US2171213A (en) | Television transmitting tube and electrode structure | |
US2289921A (en) | Photosensitive electrode | |
US3240987A (en) | Metal and glass fiber structures and electrical devices using same | |
US2836751A (en) | Cathode ray tube manufacture | |
US3099763A (en) | Cathode ray tube with silica coated phosphor screen | |
US2175692A (en) | Television transmitting tube | |
US2380505A (en) | Method of manufacturing mosaic electrodes | |
US2879420A (en) | Image orthicon target | |
US3798477A (en) | Storage tube with target having conductive surface exposed through random cracks in dielectric coating |