US2121356A - Electron tube - Google Patents
Electron tube Download PDFInfo
- Publication number
- US2121356A US2121356A US7469A US746935A US2121356A US 2121356 A US2121356 A US 2121356A US 7469 A US7469 A US 7469A US 746935 A US746935 A US 746935A US 2121356 A US2121356 A US 2121356A
- Authority
- US
- United States
- Prior art keywords
- electron
- tube
- fluorescent
- layer
- cathode ray
- 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
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- 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
- the present invention relates to electron tubes and particularly those of the type known in the art as the cathode ray or Braun tube.
- This method involves the inconvenience that even small amounts of admixed metals are extremely detrimental to the fluorescent intensity, as well as to the duration of the after glow of the flu- 3 crescent substance.
- metals having a low density and electron emitting energy for instance,-
- barium, potassium, caesium, magnesium have been found to be suitable, whereby besides the low density and the simple manner of application to be described in the following, perhaps the condition plays an important part according to which due to the strong emission of secondary electrons and the space charges thereby produced in front of the screen, compensate the detrimental influence of static charges of the fluorescent screen which may eventually still exist.
- My invention will best be understood by reference to the single figure of the drawing, which shows one embodiment thereof.
- cathode ray tube having the conventional cathode ray developing means identified on the drawing as an electron gun.
- the further electrodes have been omitted from the tube.
- Such layer can be-prcdhced in such manner that the layer material is heated in vacuum in a lateral extension L of the cathode ray tube T whose axis A is directed towards the fluorescent screen as indicated by the single figure of the accompanying drawing.
- This figure of the drawing omits the electrode systems both with respect to accelerating and deflecting the electrons within the tube.
- the material within the lateral extension L is then evaporated upon the fluorescent screen S.
- thethin metal covering serves at the same time to also continuously maintain a sufllciently high 5 vacuum after sealing of the tube (getting effect).
- a cathode ray tube comprising an envelope, an electron source at one end thereof, a coating of material adapted to fluoresce under electron impact upon the opposite end thereof, and a layer of electron permeable photo-electric conducting material coating the surface of the fluorescent material adjacent the electron source, 5 said electron permeable photoelectric conducting material comprising an alkaline earth metal capable of secondary emission.
- the cathode ray tube claimed in claim 1 characterized in that the electron permeable conducting coating is formed of a material having low density and high electron emitting properties, said electron permeable conducting coating comprising an alkaline earth metal.
- a cathode ray tube comprising an evacuated envelope, an electron source at one end thereof, a coating of material adapted to fluoresce under electron impact upon the opposite end thereof, and a thin layer of an alkali earth metal coating the surface of the fluorescent material adiacent go the electron source, saidmetal having the property of acting as a getter material.
Description
M. KNOLL ELECTRONTUBE June 21, 1938.
INVENTOR MAX KNOLL M MM Filed Feb. 21, 1955 Y E N R O T T A Patented June 21, 1938 UNITED STATES PATENT OFFICE ELECTRON TUBE Germany Application February 21, 1935, Serial No. 7,469 In Germany February 2, 1934 3 Claims.
The present invention relates to electron tubes and particularly those of the type known in the art as the cathode ray or Braun tube.
In cathode ray tubes, and more particularly in 6 those which are brought to a high vacuum, it has been found that the electrical charges reaching the luminous screen through the electron current often cause distortions of the electrical field in the vicinity of the fluorescent screen and consew quently distortions in the trace of the ray to be recorded on the luminous screen, that is, the oscillogram, picture or the like is distorted.
It already has been proposed to cover the side of the fluorescent screen situated next to the glass 15 wall of the tube by means of a metallic, conducting and transparent layer. This method has the disadvantage that yet-an absorption of the light emanating from the fluorescent screen will be caused. Moreover the purpose is thereby only 20 partially accomplished since the carrying away of the charge is not fully obtained due to the intermedially disposed insulating fluorescent substance. It furthermore has been proposed to impart conductivity to the layer of the fluorescent as substance proper by admixing a metal powder.
This method involves the inconvenience that even small amounts of admixed metals are extremely detrimental to the fluorescent intensity, as well as to the duration of the after glow of the flu- 3 crescent substance.
proposed to cover the side of the fluorescent screen next to the cathode with a conducting layer. The charge of the electrons will then be 35 directly laterally deviated after impinging on the fluorescent screen. Obviously substances chosen for the purpose of providing such covering must have only small thickness, in order to prevent an appreciable absorption of the electrons in 40 the conducting layer. Since, however, for the carrying away of the extremely low ray currents (of the order of 10- A?) a very thin layer is sufilcient an appreciable absorption of the electrons does not occur when the thickness of the layer is 45 suitably dimensioned.
. For such layers, metals having a low density and electron emitting energy, for instance,-
barium, potassium, caesium, magnesium, have been found to be suitable, whereby besides the low density and the simple manner of application to be described in the following, perhaps the condition plays an important part according to which due to the strong emission of secondary electrons and the space charges thereby produced in front of the screen, compensate the detrimental influence of static charges of the fluorescent screen which may eventually still exist. My invention will best be understood by reference to the single figure of the drawing, which shows one embodiment thereof.
Referring to the drawing, there is shown a cathode ray tube having the conventional cathode ray developing means identified on the drawing as an electron gun. For purposes of simplicity, 10 the further electrodes have been omitted from the tube.
Such layer can be-prcdhced in such manner that the layer material is heated in vacuum in a lateral extension L of the cathode ray tube T whose axis A is directed towards the fluorescent screen as indicated by the single figure of the accompanying drawing. This figure of the drawing omits the electrode systems both with respect to accelerating and deflecting the electrons within the tube. The material within the lateral extension L is then evaporated upon the fluorescent screen S. In accordance with the invention thethin metal covering serves at the same time to also continuously maintain a sufllciently high 5 vacuum after sealing of the tube (getting effect).
Having thus described the invention, what is claimed is:
1. A cathode ray tube comprising an envelope, an electron source at one end thereof, a coating of material adapted to fluoresce under electron impact upon the opposite end thereof, and a layer of electron permeable photo-electric conducting material coating the surface of the fluorescent material adjacent the electron source, 5 said electron permeable photoelectric conducting material comprising an alkaline earth metal capable of secondary emission.
2. The cathode ray tube claimed in claim 1 characterized in that the electron permeable conducting coating is formed of a material having low density and high electron emitting properties, said electron permeable conducting coating comprising an alkaline earth metal.
3. A cathode ray tube comprising an evacuated envelope, an electron source at one end thereof, a coating of material adapted to fluoresce under electron impact upon the opposite end thereof, and a thin layer of an alkali earth metal coating the surface of the fluorescent material adiacent go the electron source, saidmetal having the property of acting as a getter material.
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Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2121356X | 1934-02-02 |
Publications (1)
Publication Number | Publication Date |
---|---|
US2121356A true US2121356A (en) | 1938-06-21 |
Family
ID=7985926
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US7469A Expired - Lifetime US2121356A (en) | 1934-02-02 | 1935-02-21 | Electron tube |
Country Status (1)
Country | Link |
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US (1) | US2121356A (en) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2438668A (en) * | 1944-04-28 | 1948-03-30 | Du Mont Allen B Lab Inc | Cathode-ray tube screen and process |
US2467734A (en) * | 1945-04-12 | 1949-04-19 | Farnsworth Res Corp | Shading compensating mosaic screen electrode |
US2472988A (en) * | 1944-10-28 | 1949-06-14 | Scophony Corp Of America | Apparatus for reproducing electric signals, particularly television reproducers |
US2544690A (en) * | 1946-12-26 | 1951-03-13 | Du Mont Allen B Lab Inc | Color television |
US2553182A (en) * | 1946-11-01 | 1951-05-15 | Cage Projects Inc | Color television |
US2605434A (en) * | 1949-12-08 | 1952-07-29 | John H Homrighous | Single beam three color cathoderay tube |
US2622220A (en) * | 1949-03-22 | 1952-12-16 | Technicolor Motion Picture | Television color screen |
US2667600A (en) * | 1950-10-02 | 1954-01-26 | Cathodeon Ltd | Television pickup tube |
US2758942A (en) * | 1952-04-04 | 1956-08-14 | Hartford Nat Bank & Trust Co | Cathode-ray tube of the kind comprising a luminescent screen |
US3401293A (en) * | 1966-11-28 | 1968-09-10 | Tektronix Inc | Mesa type combined direct viewing storage target and fluorescent screen for cathode ray tube |
-
1935
- 1935-02-21 US US7469A patent/US2121356A/en not_active Expired - Lifetime
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2438668A (en) * | 1944-04-28 | 1948-03-30 | Du Mont Allen B Lab Inc | Cathode-ray tube screen and process |
US2472988A (en) * | 1944-10-28 | 1949-06-14 | Scophony Corp Of America | Apparatus for reproducing electric signals, particularly television reproducers |
US2467734A (en) * | 1945-04-12 | 1949-04-19 | Farnsworth Res Corp | Shading compensating mosaic screen electrode |
US2553182A (en) * | 1946-11-01 | 1951-05-15 | Cage Projects Inc | Color television |
US2544690A (en) * | 1946-12-26 | 1951-03-13 | Du Mont Allen B Lab Inc | Color television |
US2622220A (en) * | 1949-03-22 | 1952-12-16 | Technicolor Motion Picture | Television color screen |
US2605434A (en) * | 1949-12-08 | 1952-07-29 | John H Homrighous | Single beam three color cathoderay tube |
US2667600A (en) * | 1950-10-02 | 1954-01-26 | Cathodeon Ltd | Television pickup tube |
US2758942A (en) * | 1952-04-04 | 1956-08-14 | Hartford Nat Bank & Trust Co | Cathode-ray tube of the kind comprising a luminescent screen |
US3401293A (en) * | 1966-11-28 | 1968-09-10 | Tektronix Inc | Mesa type combined direct viewing storage target and fluorescent screen for cathode ray tube |
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