US2725483A - Inspection of electron phosphor screens - Google Patents

Inspection of electron phosphor screens Download PDF

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Publication number
US2725483A
US2725483A US163246A US16324650A US2725483A US 2725483 A US2725483 A US 2725483A US 163246 A US163246 A US 163246A US 16324650 A US16324650 A US 16324650A US 2725483 A US2725483 A US 2725483A
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United States
Prior art keywords
rays
screen
phosphor
electron
layer
Prior art date
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Expired - Lifetime
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US163246A
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English (en)
Inventor
Fitz-Hugh B Marshall
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CBS Corp
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Westinghouse Electric Corp
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Filing date
Publication date
Priority to BE503192D priority Critical patent/BE503192A/xx
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US163246A priority patent/US2725483A/en
Priority to DEW8019A priority patent/DE918828C/de
Application granted granted Critical
Publication of US2725483A publication Critical patent/US2725483A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
    • G01N23/223—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/043—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using fluoroscopic examination, with visual observation or video transmission of fluoroscopic images
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2223/00—Investigating materials by wave or particle radiation
    • G01N2223/07—Investigating materials by wave or particle radiation secondary emission
    • G01N2223/076—X-ray fluorescence

Definitions

  • My invention relates to inspection apparatus, and in particular relates to arrangements for determining the uniformity in texture, resolving power, and homogeneity of the electron phosphor layers of fluorescent screens used for reproducing, in cathode ray tubes, television receiving tubes, and various image intensifying tubes, an intensified picture image. It produces outstanding results in the inspection of relatively thin phosphor layers.
  • a fluorescent screen comprising a layer of some electron phosphor, such as zinc sulphide, on which electrons corresponding in space distribution to the optical image being intensified are incident.
  • the layer of phosphor be as uniform and perfect in resolution as possible.
  • My present invention relates to an arrangement for inspecting such screens during the course of manufacturing to reassure the required uniformity. It is particularly adapted to use in quantity production of such screens.
  • One object of my invention accordingly, is to provide a method of determining the uniformity and homogeneity of thin fluorescent screens.
  • Another object of'my invention is to provide an arrangement for inspecting any electron phosphor screen, especially when backed by a reflective coating, for imperfections, variations of thickness or sensitivity, and the like.
  • the fluorescent screen comprises an annular member 1 having a periphery suiting it to be sealedglass or otherwise attached to form a wall portion of an electrical discharge device.
  • ascreen 2 comprising a thin glass plate 3 coated on its interior surface with a substantially uniform layer 4 of a. fluorescent material such as zinc sulphide.
  • the glass plate may be sealed at its outer edge to the annular memher 1.
  • the face of the fluorescent layer may be coated with a thin layer of aluminum or nickel, thin enough to be penetrated by electrons passing through an electron lens which is positioned inside the electrical dis charge tube.
  • the annular member 1 may be affixed to any suitable support member (not shown) in the path of X-rays emanating from an X-ray tube 6 of any suitable type.
  • the tube 6 preferably has a line focal spot 7 which is arranged in a manner well known in the art, so that the X-rays to be used are emitted at a glancing angle from the target and tend to form the sharpest detail shadowgraphsf practical for a given distance of the source from the target.
  • Tubes known in the art as X-ray diffraction sources of X-rays are of this type and I have found them satisfactory.
  • the focal-spot-to-screen distance can be small so as to permit high intensity at the screen, which effect is further aided by the line focus principle.
  • the rays from line focus 7 pass through a window 8 which is preferably of beryllium.
  • window 8 which is preferably of beryllium.
  • X-rays i. e., from 1 to 5 Angstroms
  • straight wires or rods are used to cast shadows on the screen during testing, the line focus is positioned parallel to the wire.
  • the focal spot and window arrangements in the X-ray tube 6 shall produce an extremely high intensity, broad and uniform beam of X-rays.
  • the emphasis is on high intensity and sharpness of shadow detail.
  • An optical magnifying lens 13 may be usefully employed to scan the area of the screen 2 to aid in'de'termining its texture and resolving power.
  • the lead glass for operator protection may be quickly removed when the X-rays are off, for changing screens in assembly line production testing.
  • the ability of the screen 2 to properly resolve fine detail images projected upon it may be determined by positioning a fine wire grid 14 close to the inner surface of the screen 2.
  • the line focal spot is preferably' used, and the fine wires of this grid are made parallel to the line focal spot 7.
  • a permanent record of the inspection may be made by photographing the screen.
  • the X-ray diffraction type of source has the valuable property of producing a line focus which is a fine, narrow line capable of projecting a high intensity beam which is highly collimated in its transverse dimension, and can be brought much closer to the wires of the testing-grid and the phosphor screen than ordinary X-ray sources. It further produces readily a soft X-ray beam, and I take fullest advantage of the intensity of the soft X-rays by employing a beryllium or other similar window to sulfuse the phosphor with rays of a wavelength which it can effectively absorb even though it is relatively thin.
  • the line focus of the diffraction tube enormously in.- creases the intensity of the light from the phosphor rela-v tive to that obtainable with circular focal spots of equal focusing power; the correspondence between the direction of the line focus and absorbing wires parallel to it accounts for the possibility of thus increasing the radia tion intensity without losing focusing effect.
  • my X-ray device is particularly effective for phosphor screens having a metal or other opaque backing
  • the device has advantages over ultraviolet and/or electron radiation of phosphor layers devoid of such backing; for example, a. more uniform irradiation throughout the thickness of the phosphor layer.
  • a fluorescent: screen having a layer of Zinc sulphide approximately .001 centimeter thick and coated with a layer of Al metal about 0.00002 centimeter thick was positioned about ten centimeters away from the focal spot of a line-focus beryllium-window X-ray difiraction tube of the above-described type operated at 45 kilovolts and milliamperes input.
  • a 30 line per millimeter grid of tungsten wire was placed 40 mils from the electron phosphor layer. Under such conditions the light given off by the electron phos-v phor was found sufiicient to overcome the normal illumination present in a laboratory and to permit easily detailed inspection of the tungsten grid pattern in a slightly darkened room.
  • the above-mentioned screen had a diameter of one inch. Though the target-toascreen dis! tance was centimeters, measurements showed that a distance of as little as 3 centimeters (with tenfold brightness increase) would have still permitted the desired reso! lution.
  • An apparatus for inspecting a screen of electron phosphor about 0.001 centimeter thick having an opaque backing which comprises an X-ray tube having a beryllium window, means for supporting said screen in the path of X-rays projected through said window and means having a high absorbing power for X-rays positioned in the path of a portion only of the X-rays passing from said window to said screen.
  • Means for inspecting a zinc sulphide type electron phosphor screen about 0.001 centimeters thick which comprises an X-ray tube having a line focal spot and a beryllium window, means forsupporting said screen in the path of X-rays passing through said window from said fo al spo and a m r al. h i g a inear.- dg Parallel to the line of said focal spot having a high absorbing power for X-rays in the path of said X-rays which have passed from said focal spot through said window.
  • An apparatus for inspecting a thin electron phosphor screen having an opaque backing comprising an X-ray dififraction source of X-rays producing a line focus, means for supporting said screen in the path of said X-rays, and a filament of material which is a poor transmitter of X-rays positioned parallel to said focus line in said path ahead of said screen.
  • Apparatus for inspecting a layer of zinc sulphide about 0.001 centimeter thick having an opaque backing which comprises means for supporting said layer, means for producing a beam of soft X-rays and projecting said beam through said layer.
  • Apparatus for inspecting a layer of zinc sulphide about 0.001 centimeter thick and covered with a layer of metal which comprises means for supporting said layer, a line focus X-ray tube having a beryllium window positioned to project said X-rays through said layer, and wires of material opaque to said projected X-rays positioned parallel to said line focus in the path of said projected X-rays.
  • Apparatus for inspecting a layer of zinc sulphide electron phosphor about 0.001 centimeter thick which comprises means for supporting said layer, means for producing a beam of X-rays of 1 to 5 Angstroms wavelength, and projecting said beam onto said phosphor.
  • Apparatus for inspecting a layer of electron phosphor which comprises means for supporting said layer, a linear type source of X-rays, means for projecting said X-rays onto said phosphor, and means relatively opaque to X-rays and having a linear edge substantially parallel to said source in the path of said X-rays ahead of said phosphor.
  • Apparatus for inspecting a layer of electron phosphor about 0.001 centimeters thick which comprises means for supporting said layer, an X-ray tube having a beryllium window, means for projecting said X-rays through said window onto said phosphor, and means relatively opaque to X-rays in the path of said X-rays ahead of said phosphor.
  • Apparatus for inspecting a thin layer of zinc sulphide type phosphor which comprises means for supporting said layer, a linear source of X-rays, means for projecting said X-rays onto said phosphor, and means having a rectilinear edge whichis relatively opaque to X-rays and is substantially parallel to said source in the path of said X-rays ahead of said phosphor.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
US163246A 1950-05-20 1950-05-20 Inspection of electron phosphor screens Expired - Lifetime US2725483A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE503192D BE503192A (ro) 1950-05-20
US163246A US2725483A (en) 1950-05-20 1950-05-20 Inspection of electron phosphor screens
DEW8019A DE918828C (de) 1950-05-20 1952-03-02 Verfahren und Vorrichtung zur Untersuchung von Elektronenleuchtschirmen

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US163246A US2725483A (en) 1950-05-20 1950-05-20 Inspection of electron phosphor screens

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US2725483A true US2725483A (en) 1955-11-29

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Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US587883A (en) * 1897-08-10 Device for examining jewels by roentgen rays
US1370640A (en) * 1919-07-17 1921-03-08 Granger Amedee Foreign-body localizer
US1590971A (en) * 1918-02-01 1926-06-29 Goetze Otto Method of and apparatus for producing sharp rontgen imagen
US1942007A (en) * 1930-01-09 1934-01-02 Westinghouse Lamp Co Soft x-ray tube
US2055188A (en) * 1934-04-09 1936-09-22 American Cystoscope Makers Inc Fluoroscope
US2057325A (en) * 1931-02-06 1936-10-13 Philips Nv Method and device for measuring thicknesses with penetrating rays
US2120916A (en) * 1934-09-22 1938-06-14 Ralph E Bitner Light frequency converter
US2140269A (en) * 1934-12-25 1938-12-13 Leo C Pelkus Dental fluoroscopic instrument
US2189623A (en) * 1938-06-28 1940-02-06 Westinghouse Electric & Mfg Co Integrating x-ray dosage meters
US2297478A (en) * 1939-09-29 1942-09-29 Kallmann Hartmut Israel Device for the production of visible or photographic images with the aid of a beam of neutrons as depicting radiation
US2310567A (en) * 1941-01-08 1943-02-09 Gen Electric X Ray Corp X-ray apparatus and method of construction
US2430969A (en) * 1943-03-18 1947-11-18 Albert Ramsay Process and apparatus for orienting crystals
US2433129A (en) * 1943-12-30 1947-12-23 Westinghouse Electric Corp Photofluorographic camera and control
US2475596A (en) * 1945-08-13 1949-07-12 Raytheon Mfg Co Method of examining welded surfaces
US2549987A (en) * 1948-03-27 1951-04-24 Philips Lab Inc X-ray diffraction method
US2557662A (en) * 1948-11-29 1951-06-19 Research Corp Short-wave electromagnetic radiation catoptrics

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US587883A (en) * 1897-08-10 Device for examining jewels by roentgen rays
US1590971A (en) * 1918-02-01 1926-06-29 Goetze Otto Method of and apparatus for producing sharp rontgen imagen
US1370640A (en) * 1919-07-17 1921-03-08 Granger Amedee Foreign-body localizer
US1942007A (en) * 1930-01-09 1934-01-02 Westinghouse Lamp Co Soft x-ray tube
US2057325A (en) * 1931-02-06 1936-10-13 Philips Nv Method and device for measuring thicknesses with penetrating rays
US2055188A (en) * 1934-04-09 1936-09-22 American Cystoscope Makers Inc Fluoroscope
US2120916A (en) * 1934-09-22 1938-06-14 Ralph E Bitner Light frequency converter
US2140269A (en) * 1934-12-25 1938-12-13 Leo C Pelkus Dental fluoroscopic instrument
US2189623A (en) * 1938-06-28 1940-02-06 Westinghouse Electric & Mfg Co Integrating x-ray dosage meters
US2297478A (en) * 1939-09-29 1942-09-29 Kallmann Hartmut Israel Device for the production of visible or photographic images with the aid of a beam of neutrons as depicting radiation
US2310567A (en) * 1941-01-08 1943-02-09 Gen Electric X Ray Corp X-ray apparatus and method of construction
US2430969A (en) * 1943-03-18 1947-11-18 Albert Ramsay Process and apparatus for orienting crystals
US2433129A (en) * 1943-12-30 1947-12-23 Westinghouse Electric Corp Photofluorographic camera and control
US2475596A (en) * 1945-08-13 1949-07-12 Raytheon Mfg Co Method of examining welded surfaces
US2549987A (en) * 1948-03-27 1951-04-24 Philips Lab Inc X-ray diffraction method
US2557662A (en) * 1948-11-29 1951-06-19 Research Corp Short-wave electromagnetic radiation catoptrics

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