US3069578A - Image orthicon target - Google Patents

Image orthicon target Download PDF

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Publication number
US3069578A
US3069578A US19034A US1903460A US3069578A US 3069578 A US3069578 A US 3069578A US 19034 A US19034 A US 19034A US 1903460 A US1903460 A US 1903460A US 3069578 A US3069578 A US 3069578A
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US
United States
Prior art keywords
glass
target
oxide
image
tube
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
US19034A
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English (en)
Inventor
George B Hares
John L Sheldon
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.)
Corning Glass Works
Original Assignee
Corning Glass Works
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 NL262582D priority Critical patent/NL262582A/xx
Application filed by Corning Glass Works filed Critical Corning Glass Works
Priority to US19034A priority patent/US3069578A/en
Priority to GB10722/61A priority patent/GB937425A/en
Priority to DEC23777A priority patent/DE1180775B/de
Priority to FR857306A priority patent/FR1285133A/fr
Application granted granted Critical
Publication of US3069578A publication Critical patent/US3069578A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01J29/02—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
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/39—Charge-storage screens
    • H01J29/41—Charge-storage screens using secondary emission, e.g. for supericonoscope
    • H01J29/413—Charge-storage screens using secondary emission, e.g. for supericonoscope for writing and reading of charge pattern on opposite sides of the target, e.g. for superorthicon
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions

Definitions

  • a glass tube or envelope generally designated has a plain front end or face plate 11 having on its inner surface a photocathode 12 (shown in exaggerated thickness) consisting of a thin, continuous, semitranspa-rent layer usually comprising cesium, silver oxide and silver. Spaced from the photo-cathode is a glass target 13 (shown in exaggerated thickness), an improved composition for which forms the subject of this invention.
  • the target 13 is a circular membrane of glass, which may be about 40 mm. in diameter and 35 microns thick, sealed to a support ing ring 14 of metal having a thermal expansion co efficient compatible with that of the glass.
  • Such glass heretofore used for the target, was normally composed of a soda-lime-s-ilicate glass of the type used in making incandescent lamp bulbs, such as is described in Patent No. 1,369,988 and particularly in Example 4 of that patent.
  • a potassia-titania-silicate glass as described in Patent No. 2,879,420 was thought to be necessary.
  • a very fine met-a1 gauze 15 shown in exaggerated thickness
  • an electron gun 16 is provided with a grid 17 surrrounding the aperture of the gun and a multi-stage electron multiplier 18.
  • an optical image formed by a lens system (not shown) arranged in front of the face plate 11 is projected on the front surface of the photo-cathode 12.
  • Photo-electrons thereby emitted from the rear surface of the photo-cathode strike the front face of the target 13 and cause the emission therefrom of secondary electrons in larger numbers than the photo-electrons.
  • the emitted secondary electrons which are carried off by the metal gauze 15 leave electron deficiencies or positive charges on the front face of the target. Since the photo-electrons were compelled to pass through the metal gauge 15 on their way to the target 13, a pattern of individual positive charges thus remain on the front face of the target and delineate the image thereon.
  • Such charges are conducted perpendicularly but not laterally through the target glass to its rear face where they are neutralized by a scanning beam of low-velocity 3,069,578 Patented Dec. 18, 1962 of R.C.A. Review, volume 10 (June 1949), in an article entitled Development and Performance of Television Camera Tubes, by James, Johnson, and Moore.
  • the proper functioning of the glass target depends upon the rapid transfer of the positive charges of the image perpendicularly through the thin glass membrane without substantial equalization or loss by lateral conductance, as such later-a1 conductance causes poor resolution of the transmitted image.
  • the glass should have a high volume resistivity. Too high a resistivity, however, can cause the incomplete discharge of the image by the scanning beam, a phenomenon known as sticking, resulting in a transmitted signal which produces an after image on a television screen.
  • the glass target is made as thin as possible and with as low a resistivity as is consistent with the prevention of lateral conductance. Suitable targets have a volume resistivity of about 11.4- 13.0 for log R at room temperature and a thickness of about 3-5 microns.
  • raster burn Another problem associated with the target in such image orthicon tubm is known as raster burn.
  • the area of the target which is scanned by the low-velocity electron beam provided by the electron gun is enlarged by a lengthening of the horizontal and vertical tranverse of such beam, through inadvertence or design, with the attendant result that the transmitted picture appears on a television screen with a brighter area surrounding the central portion of the picture. This phenomenon is known as raster burn.
  • tubes heretofore produced has quite generally been determined by the target.
  • tubes which are entirely satisfactory when first utilized may rapidly deteriorate causing them to be unusable after as little as only a few hours, because of the appearance of one or more of the above listed defects, such as sticking or raster burn.
  • tubes which have been commercially acceptable have generally been found to have useful lives of only about 300 to 500 operating hours, at which point the amount of sticking encountered precludes their further use.
  • the principal object of the present invention is to provide a glass composition suitable for a target in an image orthicon tube which is more resistant to common defects, such as sticking and raster burn, to provide an increase in the useful life of the tube.
  • Another object is to provide a target which can be utilized in an image orthicon tube regardless of the type of photo-cathode utilized in combination therewith.
  • such object is achieved by utilizing a target consisting of a glass having a volume resistivity of between about 6.3 l0 and 1000 l0 ohms-cmfsaid glass containing a total of at least 2% by weight of at least one readily reducible metal oxide selected from the group consisting of lead oxide, zinc oxide, bismuth oxide, iron oxide, cadmium oxide, and copper oxide.
  • readily reducible metal oxides means oxides of metals having oxidation potentials, referred to the hydrogen-hydrogen ion couple as zero, when measured at C. of less than +0.8 volt for the reaction M M -l-ne. While many elements satisfy this basic requirement, many, such as the halogens and mercury, cannot readily be incorporated in sufiicient quantity in the glass as they are volatile at ordinary glass-melting temperatures. Others, such as the noble metals and tin, are not satisfactory because neither the metals nor their oxides are appreciably soluble in glasses. Still others are impractical because of their cost and their tendency to precipitate from the glass during the reworking necessary to produce the thin-walled membranes and to seal them to metal rings.
  • glass compositions which can be used for targets to obtain the advantages of this invention can be prepared by melting the batches set forth in parts by weight in Table I.
  • Table I 92% Lead Silicate- 4
  • the Sb O and AS203 function as fining agents and have no substantial effect on-the fundamental properties of the glass.
  • the fining agents are quite volatile at the temperatures utilized for melting such batches and are present in the batches in relatively small amounts, they have not been included in Table II. Additionally, minor amounfi of a decolorizer, such as Mn0 may also be added to the glasses.
  • the batches melt readily either in a closed pot or in a tank, and are melted under oxidizing conditions at a temperature of about 1300- 0 C.
  • the glass should be stirred during melting and fining in order to minimize cords.
  • glasses containing about 12% to about 20% by weight of Na O are particularly suitable examples of glasses having the desired resistivity because of the ease of melting and working such glasses.
  • other glass modifying ingredients such as aluminum oxide and boric oxide, and other divalent metal oxides (e.g. MgO, CaO, SiO, and E210) may be included therein to modify the glass working proper-ties or characteristics of the resultant materials such as thermal expansion coefficient and durability.
  • glasses containing lead oxide are especially suitable because of the large amount of lead oxide which can be included in a glass without adversely affecting durability, stability against devitrification and the like.
  • Particularly suitable are lead oxide glasses comprising by weight 50-75% SiO 12 20% Na O, 1035% PbO, 05% K 0, the total R 0 (Na O-l-K o) not exceeding 20% said oxides comprising at least 85% of the glass composition.
  • an image orthicon tube comprising a glass envelope containing in longitudinal arrangement a photo cathode, a grid of fine metal gauze, a thin glass target and an electron gun, the improvement which comprises a target of a glass having a resistivity of between 6.3 x and 1000 10 ohm-cm. at 25 C. and containing a total of at least 2% of at least one readily reducible metal oxide selected from the group consisting of lead oxide, bismuth oxide, zinc oxide, copper oxide, cadmium oxide and iron oxide.
  • an image orthicon tube comprising 'a glass envelope containing in longitudinal arrangement a photocathode, a grid of fine metal gauze, a thin glass target and an electron gun, the improvement which comprises a target of a glass having a resistivity of between 6.3)(10 and 1000x10 ohm-cm. at 25 C. and comprising by weight of 50-75% SiO about 12-20% Na O, at least a total of 2% of at least one readily reducible metal oxide selected from the group consisting of lead oxide, bismuth oxide, zinc oxide, copper oxide, cadmium oxide and iron oxide, said essential constituents comprising at least 80% by weight of the glass.
  • an image orthicon tube comprising a glass envelope containing in longitudinal arrangement a photo" cathode, a grid of fine metal gauze, a thin glass target and an electron gun, the improvement which comprises a target of a glass comprising by weight -75% SiO 12- 20% Na O, 10-35% PbO, 0-5% K 0, the total R 0 not exceeding 20%, said oxides comprising at least 85% of the glass composition.
  • an image orthicon tube comprising a glass envelope containing in longitudinal arrangement a photocathode, a grid of fine metal gauze, a thin glass target and an electron gun, the improvement which comprises utilizing a target of the glass consisting essentially by weight of about SiO about 13% Na O, about 24% lead oxide, and about 3% of aluminum oxide.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Glass Compositions (AREA)
  • Surface Treatment Of Glass (AREA)
  • Conductive Materials (AREA)
US19034A 1960-03-31 1960-03-31 Image orthicon target Expired - Lifetime US3069578A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL262582D NL262582A (en, 2012) 1960-03-31
US19034A US3069578A (en) 1960-03-31 1960-03-31 Image orthicon target
GB10722/61A GB937425A (en) 1960-03-31 1961-03-23 Image orthicon target
DEC23777A DE1180775B (de) 1960-03-31 1961-03-29 Speicherplatte fuer Superorthikon-Bildroehren
FR857306A FR1285133A (fr) 1960-03-31 1961-03-30 Cible pour tube image-orthicon

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US19034A US3069578A (en) 1960-03-31 1960-03-31 Image orthicon target

Publications (1)

Publication Number Publication Date
US3069578A true US3069578A (en) 1962-12-18

Family

ID=21791081

Family Applications (1)

Application Number Title Priority Date Filing Date
US19034A Expired - Lifetime US3069578A (en) 1960-03-31 1960-03-31 Image orthicon target

Country Status (4)

Country Link
US (1) US3069578A (en, 2012)
DE (1) DE1180775B (en, 2012)
GB (1) GB937425A (en, 2012)
NL (1) NL262582A (en, 2012)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3202854A (en) * 1961-02-21 1965-08-24 Rca Corp Pickup tube target having an additive therein for reduced resistivity
US3236686A (en) * 1962-01-02 1966-02-22 Gen Electric Storage electrode
US3350591A (en) * 1961-02-21 1967-10-31 Rca Corp Indium doped pickup tube target
US3534209A (en) * 1964-01-02 1970-10-13 Gen Electric Image orthicon target assembly and sealing glass composition therefor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1168415A (en) * 1968-07-31 1969-10-22 Mullard Ltd Improvements in or relating to Image Intensifiers
EP0560555B1 (en) * 1992-03-11 1997-02-05 The British Glass Manufacturers Confederation Glass compositions

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2587830A (en) * 1949-06-29 1952-03-04 Cinema Television Ltd Image-converting device
US2879420A (en) * 1957-08-28 1959-03-24 Corning Glass Works Image orthicon target
US2964414A (en) * 1958-04-23 1960-12-13 Corning Glass Works Glass composition and method of making it

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2473220A (en) * 1941-08-16 1949-06-14 Rca Corp Method of manufacturing target electrodes
NL92219C (en, 2012) * 1953-08-04
US3061752A (en) * 1958-07-28 1962-10-30 English Electric Valve Co Ltd Television camera tubes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2587830A (en) * 1949-06-29 1952-03-04 Cinema Television Ltd Image-converting device
US2879420A (en) * 1957-08-28 1959-03-24 Corning Glass Works Image orthicon target
US2964414A (en) * 1958-04-23 1960-12-13 Corning Glass Works Glass composition and method of making it

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3202854A (en) * 1961-02-21 1965-08-24 Rca Corp Pickup tube target having an additive therein for reduced resistivity
US3350591A (en) * 1961-02-21 1967-10-31 Rca Corp Indium doped pickup tube target
US3236686A (en) * 1962-01-02 1966-02-22 Gen Electric Storage electrode
US3534209A (en) * 1964-01-02 1970-10-13 Gen Electric Image orthicon target assembly and sealing glass composition therefor

Also Published As

Publication number Publication date
GB937425A (en) 1963-09-18
DE1180775B (de) 1964-11-05
NL262582A (en, 2012)

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