US2093166A - Electric discharge device - Google Patents

Electric discharge device Download PDF

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Publication number
US2093166A
US2093166A US33330A US3333035A US2093166A US 2093166 A US2093166 A US 2093166A US 33330 A US33330 A US 33330A US 3333035 A US3333035 A US 3333035A US 2093166 A US2093166 A US 2093166A
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US
United States
Prior art keywords
electrode
electron
tube
multiplier
multiplying
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
Application number
US33330A
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English (en)
Inventor
Leslie E Flory
George A Morton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to NL45478D priority Critical patent/NL45478C/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US33330A priority patent/US2093166A/en
Priority to DER96934D priority patent/DE763126C/de
Priority to GB20737/36A priority patent/GB478967A/en
Application granted granted Critical
Publication of US2093166A publication Critical patent/US2093166A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01J29/023—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof secondary-electron emitting electrode arrangements

Definitions

  • Our invention relates to electric discharge devices; more particularly to cathode ray tubes and methods for utilizing the same in television transmitters and the like.
  • a cathode ray tube of the general type to which our invention more especially relates comprises a target element, constituted by a plurality of minute photo-sensitive particles insulatingly supported upon a metallic back-plate, on which target element an optical image of a scene to be transmitted is projected.
  • the tube includes an electron source and means are provided whereby a beam of electrons from the source may be caused to scan the photosensitive particles whereby, when the device is in operation, the sequential neutralization of the electrical charges acquired by the particles produces a train of electrical impulses in an output circuit connected to the back-plate, which impulses correspond in amplitude to the light intensity of the elemental areas of the optical image.
  • an object of our invention to provide a combined cathode ray television transmitting tube and amplifier that shall be less noisy in operation than devices heretofore known.
  • Another object of our invention is to provide a combined television transmitting tube and amplifier that shall be more eflicient than devices heretofore known, especially with respect to the amplification of currents at the higher frequencies generated during the scanning of an optical image.
  • Another object of our invention is to provide a combined cathode ray television transmitting tube and amplifier, the output current from which shall be substantially devoid of spurious signals that have no relation to the scene being televised when the system is in operation.
  • a still further object of our invention is to provide a method for electronically amplifying a train of electrical currents corresponding to an optical image.
  • Fig. 1 is a view in perspective of a device constructed according to our invention, portions of the device being broken away to more clearly show the electrode structure,
  • Fig. 2 is a diagram exemplifying the connection of the various tube elements to potential sources during the operation of the device as a television transmitter, and
  • Fig. 3 is a view in perspective of several combined secondary emitters and electron-lens elements.
  • a cathode ray tube of the type to which our invention pertains is constituted by a bulbous evacuated container I having an elongated neck portion 3 wherein is mounted an electron source of the type commonly designated an "electron gun".
  • the electron gun comprises a thermionic cathode 2 (not shown in Fig. l but exemplified in Fig. 2) surrounded by a grid element I coaxial therewith and includes a cylindrical first anode coaxial.
  • the inner surface of the neck portion of the container, adjacent to the end of the first anode, is provided with a metallic coating H, to which is connected an exteriorly extending conductor 2i.
  • the coating has the double function of focusing the cathode ray to a fine spot upon the target and of accelerating photo and secondary electrons away from the photosensitive globules during the scanning operation.
  • the metallic coating may also extend over the whole inner surface of the bulb, with the exception of an area sufilciently large to permit focusing of an optical image on the target. The more extensive coating, if utilized, prevents the walls of the tube from acquiring charges and gives rise to optimum fieldconditions.
  • the ray deflecting coils usually four in number, one pair for hurlzontal and one pair for vertical deflection, are omitted.
  • an optical image of the scene is focused sharply upon the surface of the target carrying the photosensitive particles.
  • the light causes emission from the particles of photoelectrons which are accelerated toward the conductive coating within the neck portion of the tube.
  • each minute globule acquires a charge proportional to the light intensity of the elemental area of the optical image that is focused upon it.
  • the scanning operation as each globule is struck by the beam, its charge is neutralized and, at the same time, secondary electrons ,are emitted from the globule, their number varying in proportion to the neutralized charge.
  • one of the objects of our invention is to make use: of the secondary electrons rather than the changes in the electrical condition of the device occasioned by the successive neutralizing of the minute charges acquired'by the particles.
  • an electron multiplier of the type that we may use is constituted by an N shape evacuated container 23 in one end of which is mounted a cylindrical accelerating electrode 25 and in the other end of which is mounted an output electrode 21.
  • the end of the cylinder toward the cathode ray tube may be covered by a metallic screen 26 which somewhat improves the operation of the device.
  • An electrode 29 capable of secondary emission is mounted within the N- shape container at the junction between the first leg thereof and the connecting portion between it and the second leg and a similar electrode 3
  • Each secondary electron emissive electrode hereinafter referred to as a multiplying electrode, may be so disposed that the axes of the leg and connecting portion adjacent thereto make substantially equal angles therewith.
  • an electron lens is disposed between the said electrode and the first multiplying electrode 29.
  • This lens is constituted by an electrostatic field which is set up between the end of the accelerating electrode cylinder and a metallic coating 33 upon the inner wall of the first leg of the container to which an appropriate positive potential may be applied as will hereinafter be explained more in detail.
  • a second electron lens constituted by a plurality of spaced apart conductive wall coatings 31 and 39, between the first multiplying electrode and the second multiplying electrode. To these coatings the proper positive potentials may also be applied, as will later be shown.
  • the screen 35 is not an absolute essential of our improved device. If it is omitted, the first element 31 of the electron lens adjacent to the first multiplying electrode, it maintained at a sufficiently high positive potential with respect to the electrode 29, will serve to remove the secondary electrons therefrom and to direct them toward the next multiplying electrode.
  • the second leg of the container may be replaced by a second connecting tube provided with an additional accelerating screen, analogous to the screen element 35, as well as suitable electron-lens-forming elements, and the secondary electrons from the second emitter 3
  • a second connecting tube provided with an additional accelerating screen, analogous to the screen element 35, as well as suitable electron-lens-forming elements, and the secondary electrons from the second emitter 3
  • the accelerating cylinder 25 is made of nickel, which material may also be utilized for the accelerating screen electrode 35.
  • are of pure silver, substantially one inch in diameter and tenthousandths of an inch thick. To enhance secondary emission, the active surface of each multiplying electrode may be oxidized and caesiated, as explained in the Morton application.
  • the output electrode 21 may be made of tantalum or an analogous metal, three-quarters of an inch in diameter and five-thousandths of an inch thick.
  • the glass envelope was first fabricated in the form shown, the ends of the legs and the junctions between the legs being left open in order to permit the sealing therein of the respective electrode-supporting presses.
  • the positions of the metallic coatings on the glass were marked off and, on the inside of the blank, was deposited a commercially available platinizing solution following the marks previously made.
  • the whole blank was then heated to approximately 400 centigrade in order to reduce this platinizing solution to metallic platinum.
  • the electrodes, previously described, were mounted on the wires of the glass presses which were then sealed in place.
  • the tube was sealed to a high vacuum system by means of a tubulation (not shown), through which the tube could be evacuated.
  • a caesium compound such as caesium chromate
  • a reducing agent such as aluminum powder or silicon powder
  • the tube was then baked at 450 centigrade, being evacuated at the same time. The bake continued for approximately thirty minutes after the oven reached the final temperature. After the baking, the tube was cooled and a small amount of pure oxygen was introduced into it at a pressure of approximately 1 mm. of mercury. The cathode and multiplying electrodes were next oxidized by passing an electrical discharge from these elements to some other element in the tube until the electrode surfaces acquired a bluish-green tinge. The oxygen was then pumped out and the pellets of caesium compound and reducer were heated sufiiciently to start the reaction which yields metallic caesium. The metallic caesium was driven, by means of heating the appendage, into the main body of the tube. The tube was once more baked at 200 centigrade for approximately ten minutes andallowed to cool. The caesium appendage was then sealed off the tube and the tube sealed off the vacuum system. 4
  • the multiplier is sealed to the cathode ray tube before the first mentioned evacuation step is initiated. Also, the subsequent steps of oxidizing and caesiating the electrodes of the multiplier and the surface of the target of the cathode ray tube are taken simultaneously.
  • the caesium would be deposited upon the lens-elements and the electrodes other than those which are intended for primary or secondary emission. Such is undoubtedly the case, but, by reason of the greater affinity of caesium for an oxide, particularly silver oxide, when the tube was heated in the final heating, most of the caesium was driven off of the other elements and was taken up by the oxidized silver electrodes.
  • the caesium forms a chemical compound with the silver oxide which is reasonably stable, although the actualchemical reaction that takes place is not definitely and accurately known to us.
  • Such potentials may be supplied from any well regulated D. C. potential source, as exemplified in the drawings by a potential divider ll-Ma to the negative end of which the grid or control element 5 of the cathode ray tube is connected and to the positive end of which the output electrode 21 of the multiplier is connected over a circuit including an impedance device 43 connected between the grid 45 and cathode 41 of an output amplifier tube 49. From an inspection of Fig. 2, I
  • the cathode of the transmitting tube is variably connected to the potential source at a point more positive than the connection to the source of the grid or control element.
  • Such variable connection is for the purpose of properly adjusting the static bias on the transmitting tube to the best operating point.
  • the various elements of the combined system may be connected, respectively, to points upon the potential source successively more positive than the connection thereto of the grid or control element inthe cathode ray tube.
  • the first electron lens element 33 and the first multiplying electrode 29 may be connected together, that the second lens element 31 and the screen 35 may receive the same potential and that the second multiplying electrode 3
  • and 39 mentioned, shown in Fig. 2 as being directly connected together outside of the device may be physically continuous within the container. Such modification is exemplified by Fig. 3.
  • each particle When an optical image is focused upon the layer of particles l3 in the transmitting tube each particle, according to our present understanding, emits photo-electrons which are drawn over toward the screen 26, thus causing the said particles to acquire charges, respectively, that are proportional to the light intensity of the elemental areas of the optical image.
  • the charges are sequentially released, as heretofore mentioned, and at the same time secondary electrons are emitted in an amount varying in proportion to the neutralized charges.
  • the secondary electrons are drawn over into the electron multiplier by reason of the fact that the accelerating cylinder and the screen 26 are maintained at a potential which is high relative to the potential of the focusing elements [9. Once within the accelerating cylinder the electrons are subjected to the potential of the first multiplying electrode and are accelerated toward it.
  • the cylinder and focusing element 33 together constitute an electron. lens which focuses and directs electrons toward the first multiplying electrode 29.
  • the secondary electrons emitted from the electrode 29 are given an initial acceleration toward the second multiplying electrode by means of the screen 35.
  • the electrons emitted by the first multiplying electrode are directed and focused upon the second multiplying electrode by means of an electron lens constituted by the coatings 31 andv 39.
  • the secondary electrons Upon reaching the second multiplying electrode 50 3
  • thermore it is entirely feasible to connect a plurality of separate multipliers to the transmitting tube at different points and to combine the output currents therefrom in parallel in a. single output resistor.
  • the output currents therefrom may be so mixed as to give complete control of picture shading and background.
  • An electric discharge device constituted by a container in which are disposed a mosaic of light sensitive elements and an electron gun, in combination with an electron multiplier, the vacuous space of the said container and multiplier being continuous.
  • the electron multiplier comprises a plurality of electrodes capable of secondary emission and means constituting an electron-lens for focusing secondary-electrons from one electrode to another.
  • the electron multiplier comprises a plurality of electrodes capable of secondary emission and means constituting an electron-lens intermediate two adjacent electrodes for focusing secondary electrons from one electrode to another, at least 1 one of said electrodes being electrically connected to an element of said lens.
  • the electron multiplier is constituted by an evacuated container in which are disposed a plurality of electrodes capable of secondary emission as well as means for focusing upon one of said electrodes electrons emitted from another of said electrodes, and wherein at least one of the electrodes and a portion of the focusing means adjacent thereto are constituted by intersecting substantially cylindrical elements.
  • An evacuated container in which are disposed a target, constituted by a plurality of photosensitive particles insulatingly supported upon a common element, and a gun for sequentially bombarding the particles with electrons to cause them to emit secondary electrons, in combination with an electron multiplier into which said secondary electrons may be drawn to therein cause the emission of still further secondary electrons, whereby the secondary emission currents from the target may be amplified.
  • the electron multiplier is of the electrostatic type and is constituted by an evacuated appendage in which is disposed an electrode capable of secondary emission and an output electrode, the vacuous space in the container and the appendage being continuous and the secondary emissive electrode being accessible to secondary electrons originating in the container.
  • a combined secondary electron emissive electrode and electron focusing electrode constituted by a plurality of intersecting substantially cylindrical elements the inner surface of at least one of said elements being treated to enhance secondary emission.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Electron Tubes For Measurement (AREA)
US33330A 1935-07-26 1935-07-26 Electric discharge device Expired - Lifetime US2093166A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL45478D NL45478C (enrdf_load_stackoverflow) 1935-07-26
US33330A US2093166A (en) 1935-07-26 1935-07-26 Electric discharge device
DER96934D DE763126C (de) 1935-07-26 1936-07-26 Speichernder Bildfaenger mit einseitiger Mosaikelektrode
GB20737/36A GB478967A (en) 1935-07-26 1936-07-27 Improvements in or relating to electric discharge devices

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US33330A US2093166A (en) 1935-07-26 1935-07-26 Electric discharge device

Publications (1)

Publication Number Publication Date
US2093166A true US2093166A (en) 1937-09-14

Family

ID=21869779

Family Applications (1)

Application Number Title Priority Date Filing Date
US33330A Expired - Lifetime US2093166A (en) 1935-07-26 1935-07-26 Electric discharge device

Country Status (4)

Country Link
US (1) US2093166A (enrdf_load_stackoverflow)
DE (1) DE763126C (enrdf_load_stackoverflow)
GB (1) GB478967A (enrdf_load_stackoverflow)
NL (1) NL45478C (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2478163A (en) * 1944-12-30 1949-08-02 Gen Aniline & Film Corp Logarithmic photometer

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1450265A (en) * 1919-04-18 1923-04-03 Westinghouse Electric & Mfg Co Hot-cathode tube
FR582428A (fr) * 1923-09-15 1924-12-18 Tube électronique à plaque multiple
DE503899C (de) * 1924-03-18 1932-03-31 Apollinar Zeitlin Elektrischer Fernseher
US1903569A (en) * 1926-09-15 1933-04-11 Kenneth W Jarvis Electron tube
US1970036A (en) * 1928-01-09 1934-08-14 Television Lab Inc Photoelectric apparatus
US1955899A (en) * 1930-09-25 1934-04-24 Rca Corp Method and system for communication by television
US1920863A (en) * 1932-10-07 1933-08-01 Jr Matthew S Hopkins Amplification of radiant energy
GB419452A (en) * 1933-05-05 1934-11-05 Emi Ltd Improvements in or relating to television
NL53689C (enrdf_load_stackoverflow) * 1933-10-07

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2478163A (en) * 1944-12-30 1949-08-02 Gen Aniline & Film Corp Logarithmic photometer

Also Published As

Publication number Publication date
GB478967A (en) 1938-01-27
DE763126C (de) 1952-05-23
NL45478C (enrdf_load_stackoverflow)

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