US3456311A - Method and apparatus for adjusting interelectrode spacing in a cathode-ray tube - Google Patents

Method and apparatus for adjusting interelectrode spacing in a cathode-ray tube Download PDF

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Publication number
US3456311A
US3456311A US594241A US3456311DA US3456311A US 3456311 A US3456311 A US 3456311A US 594241 A US594241 A US 594241A US 3456311D A US3456311D A US 3456311DA US 3456311 A US3456311 A US 3456311A
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US
United States
Prior art keywords
cathode
layer
electrode
capacitance
thickness
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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
US594241A
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English (en)
Inventor
Gerardus Servaa Schrijnemakers
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US Philips Corp
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US Philips Corp
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Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
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Publication of US3456311A publication Critical patent/US3456311A/en
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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
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/04—Manufacture of electrodes or electrode systems of thermionic cathodes
    • 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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/485—Construction of the gun or of parts thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49099—Coating resistive material on a base

Definitions

  • the invention relates to a method and an arrangement for manufacturing an oxide-coated cathode for use in a cathode-ray tube in which the distance from the emissive surface to an adjacent electrode is adjusted to a desired low value by capacitance measurement.
  • the invention relates more particularly to a method and an arrangement in which an excessively thick oxide layer is reduced mechanically to the desired thickness.
  • the thickness of an emissive layer of a cathode can be reduced by mechanical operations such as pressing, scraping, planing, grinding or milling. Furthermore, the distance from the emissive layer of an oxide-coated cathode to an adjacent or control electrode can be adjusted by controlling the capacitance between the cathode and this adjacent electrode or an electrode disposed behind it, i.e., first anode. The mechanism for modifying the distance from the cathode surface to the adjacent electrode can be controlled by the capacitance between the cathode and an adjacent electrode. When this capacitance has reached a predetermined value, the arrangement is stopped.
  • this distance between cathode and control electrode depends upon the remaining tolerances of the mechanical dimensions of the system such as the diameter of the opening and the thickness of the material of the control electrode and the first anode and their relative distances.
  • the capacitance between the cathode and the first anode is also determined by the ratio between the thickness and the dielectric constant of the emissive layer. Since the dielectric constant of the layer depends upon the density of this layer and hence also upon the shrinkage occurring during drying of the layer after the application of the oxides from a suspension, this dielectric constant is not always the same. Consequently, the thickness of the carbonate layer is not always constant and variations are obtained in the distance between the surface of the layer and the adjacent electrode, while the fluctuation of the cut-off voltage also increases.
  • the thickness of an originally excessively thick emissive layer is reduced in dependence upon the dielectric constant of the layer so that the quotient of layer thickness and dielectric constant ultimately exhibits a predetermined value which avoids the aforesaid disadvantages.
  • a dense layer having a high dielectric constant must have a proportionally greater thickness.
  • the surface of the emissive layer must always lie at the same distance from the adjacent electrode after the capacitatlve adjustment of the cathode with respect to the subsequent electrodes of an electron gun, since in the case of a layer of greater density, the preadjusted capacitative value is already reached when the cathode support still is at a greater distance from the adjacent electrode. Consequently, when the layer of greater density has a greater thickness, its surface lies at the same distance from this electrode as the surface of a layer of smaller density and hence, of smaller thickness despite the greater distance between the support and the adjacent electrode.
  • the cathode support is located closer to the adjacent electrode when the predetermined capacitance value is reached.
  • the thickness of the originally excessively thick layer may be reduced by pressing; in this case, however, the density of the carbonate layer does not increase uniformly but the upper layer is compressed to a greater extent than the parts of the layer lying closer to the cathode support.
  • the layer is scraped or planed in known manner by means of a sharp knife.
  • the holder of the knife also includes an electrode whose capacitance with respect to the cathode support and the emissive layer is measured. After each scraping movement, the increase in capacitance is measured and the scraping movement may be repeated depending upon whether the measured capacitance still deviates from the adjusted measuring value. Moreover, in this method, the roughness of the emissive layer is completely eliminated.
  • FIG. 1 shows diagrammatically an arrangement for gradually planing an excessively thick emissive layer to the desired thickness
  • FIG. 2 shows diagrammatically a suitable bridge circuit for measuring the capacitance between the cathode and an adjacent electrode.
  • a metal support 1 carries an emissive layer 2 of a hood-shaped cathode for use in a cathode-ray tube.
  • Cathode support 1 is held, for example, by vacuum on a supporting member 3 which is centered in cathode tube 4 by means of a centering member 5.
  • Cathode tube 4 is welded to metal support 1.
  • Emissive layer 2 is applied so that it has an excessively great thickness.
  • a holder '6 provided with a knife 7 is arranged which may act as a plane. Furthermore, holder 6 is provided with a central electrode 8 which is secured in holder 6 by means of insulating material 9. The position of knife 7 with respect to electrode 8 and holder 6 is adjustable so that emissive layer 2 and electrode 8 may be separated by a layer of air. Holder 6 and supporting member 3 with cathode 1 can be relatively moved to and fro and can be caused to move more or less closely towards each other by a fine adjustment. An alternating voltage supplied by a bridge circuit is applied to electrode 8 and cathode 1 and the emissive layer is gradually planed until the capacitance between electrode 8 and cathode 1 reaches a pre-determined measured value. The movement of cathode 1 with respect to holder 6 can be stopped automatically or manually when the measured value is reached. In the case of automatic control, a servomechanism is connected between the bridge circuit and the driving means.
  • thelevel difference between the knife and -electrode--- 6 with electrode 8 must be varied in order to obtain the desired condition after a second planing movement.
  • the second planing operation can be carried out in a few steps if this should be required with a view to the structure of the carbonate layer.
  • Y Electrode 8 preferably has an operative diameter which corresponds with the opening in the first electrode of the electron gun into which the cathode must be incorporated and the position of the upper surface of the emissive layer .with respect to this electrode is adjusted. Consequently,
  • the thickness of the emissive layer is reduced in dependence upon the density of this layer and hence upon the dielectric constant thereof in a manner such that a layer of greater density obtains a greater thickness.
  • the capacitance caused by this layer increases more rapidly so that the pre-deterrnined capacitance value between the cathode and the electrode 8 is already reached when the support of the cathode 1 still lies at a greater distance from the electrode 8.
  • the position of the support varies in dependence upon the density of the emissive layer but when the pre-determined capacitance value is reached, the distance between the surface of this layer and the adjacent electrode will invariably be the same.
  • the material of the emissive layer 2 removed by scraping or planing is drawn away through a pipe 10.
  • the alternating current of the source of supply 10 is applied to the branch connected to ground and including the impedances 12 and 13 and to the branch including a capacitor 14 and the planing device. If the impedance between the points 1 and 8 exceeds by many times the impedance 12, the voltage between the holder 6 and the electrode 8 is so low that the system 1-6-8 may be considered as a capacitative screening ring, which, as stated above, is a condition.
  • the bridge is first adjusted by meansof a device 11 having a given measuring capacity and subsequently the capacitance between the electrode 8 and the cathode 1.
  • the difference voltage supplied by the bridge are visualized on a measuring instrument 17 by means of a transformer and a rectifier and amplifier 16, or are applied to a servoapparatus.
  • a method of manufacturing a cathode having an emissive coating of electron emittingoxides for use in a cathode-ray tube comprising the steps of mechanically reducing an excessively thick oxide layer, while comparing the quotient of layer thickness of dielectric constant with that of 'a layer of given thickness and dielectric constant to thereby control the thickness of the layer being reduced to a desired value.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
  • Electron Sources, Ion Sources (AREA)
US594241A 1965-12-07 1966-11-14 Method and apparatus for adjusting interelectrode spacing in a cathode-ray tube Expired - Lifetime US3456311A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6515843A NL6515843A (ko) 1965-12-07 1965-12-07

Publications (1)

Publication Number Publication Date
US3456311A true US3456311A (en) 1969-07-22

Family

ID=19794836

Family Applications (1)

Application Number Title Priority Date Filing Date
US594241A Expired - Lifetime US3456311A (en) 1965-12-07 1966-11-14 Method and apparatus for adjusting interelectrode spacing in a cathode-ray tube

Country Status (8)

Country Link
US (1) US3456311A (ko)
BE (1) BE690736A (ko)
CH (1) CH462961A (ko)
DE (1) DE1564473A1 (ko)
ES (2) ES334173A1 (ko)
FR (1) FR1504170A (ko)
GB (1) GB1151438A (ko)
NL (1) NL6515843A (ko)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3534455A (en) * 1968-05-03 1970-10-20 Us Army Method of making thermionic cathodes
EP2145772A2 (en) 2008-07-16 2010-01-20 FUJIFILM Corporation Method of manufacturing aluminum alloy plate for lithographic printing plate, aluminum alloy plate for lithographic printing plate, lithographic printing plate support and presensitized plate

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2321413A (en) * 1941-07-28 1943-06-08 Raymond C Palmer Planer and shaper attachment for lathes
US2700000A (en) * 1952-02-27 1955-01-18 Philips Corp Thermionic cathode and method of manufacturing same
US2986799A (en) * 1957-01-03 1961-06-06 Philips Corp Method of making cathodes
US3045320A (en) * 1959-03-12 1962-07-24 Raytheon Co Impregnated cathodes
US3150021A (en) * 1961-07-25 1964-09-22 Nippon Electric Co Method of manufacturing semiconductor devices
US3261082A (en) * 1962-03-27 1966-07-19 Ibm Method of tailoring thin film impedance devices
US3284878A (en) * 1963-12-09 1966-11-15 Corning Glass Works Method of forming thin film resistors
US3299332A (en) * 1961-07-10 1967-01-17 Murata Manufacturing Co Semiconductive capacitor and the method of manufacturing the same
US3330696A (en) * 1967-07-11 Method of fabricating thin film capacitors

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3330696A (en) * 1967-07-11 Method of fabricating thin film capacitors
US2321413A (en) * 1941-07-28 1943-06-08 Raymond C Palmer Planer and shaper attachment for lathes
US2700000A (en) * 1952-02-27 1955-01-18 Philips Corp Thermionic cathode and method of manufacturing same
US2986799A (en) * 1957-01-03 1961-06-06 Philips Corp Method of making cathodes
US3045320A (en) * 1959-03-12 1962-07-24 Raytheon Co Impregnated cathodes
US3299332A (en) * 1961-07-10 1967-01-17 Murata Manufacturing Co Semiconductive capacitor and the method of manufacturing the same
US3150021A (en) * 1961-07-25 1964-09-22 Nippon Electric Co Method of manufacturing semiconductor devices
US3261082A (en) * 1962-03-27 1966-07-19 Ibm Method of tailoring thin film impedance devices
US3284878A (en) * 1963-12-09 1966-11-15 Corning Glass Works Method of forming thin film resistors

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3534455A (en) * 1968-05-03 1970-10-20 Us Army Method of making thermionic cathodes
EP2145772A2 (en) 2008-07-16 2010-01-20 FUJIFILM Corporation Method of manufacturing aluminum alloy plate for lithographic printing plate, aluminum alloy plate for lithographic printing plate, lithographic printing plate support and presensitized plate

Also Published As

Publication number Publication date
DE1564473A1 (de) 1970-01-22
GB1151438A (en) 1969-05-07
ES344092A1 (es) 1968-09-16
NL6515843A (ko) 1967-06-08
ES334173A1 (es) 1968-01-16
BE690736A (ko) 1967-06-05
CH462961A (de) 1968-09-30
FR1504170A (fr) 1967-12-01

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