US2798180A - Cathode-ray tubes for use in television receivers - Google Patents

Cathode-ray tubes for use in television receivers Download PDF

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Publication number
US2798180A
US2798180A US465489A US46548954A US2798180A US 2798180 A US2798180 A US 2798180A US 465489 A US465489 A US 465489A US 46548954 A US46548954 A US 46548954A US 2798180 A US2798180 A US 2798180A
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United States
Prior art keywords
cathode
porous body
alloy
supply
container body
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Expired - Lifetime
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US465489A
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English (en)
Inventor
Winter Erno
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.)
Egyesuelt Izzolampa es Villamossagi Rt
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Egyesuelt Izzolampa es Villamossagi Rt
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/28—Dispenser-type cathodes, e.g. L-cathode
    • 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
    • H01J29/04—Cathodes

Definitions

  • This invention relates to cathode-ray tubes for use in television receivers. It is known that in tubes of this kind which are provided with a luminescent screen, negative ions are emitted together with electrons and said negative ions while bombarding energetically said screen cause the so-called ion-burn on the image screen of the tube. This ion burn forming a dark spot is generally worst in the centre of the screen.
  • a further object of this invention is a cathode-ray tube for television receivers with a new kind of cathode preventing substantially the emission of negative ions without providing any special and expensive devices.
  • a still further object of this invention is a cathode for cathode-ray tubes which are practically free from ion spots.
  • VV a so-called supply cathode comprising a container body, a sintered porous body forming a closing member ⁇ for said container body made of a refractory metal having a melting point higher than that of nickel, said container body and said porous body enclosing a supply chamber, the pores ofsaid porous body forming the only passages fromy within said chamber onto the outer surface of said porous' sintered0 body.
  • a substance adapted to work as an active material of said cathode,l said substance comprising preferably more than one earth alkaline compound other than a carbonate, azide, boride, nitrate and having,y at least in activated condition ⁇ y of the cathode, a barium oxide content, the
  • the activating substance of this cathode consists of a compound and/ or an alloy containing at least one alkaline or earth alkaline metal.
  • a cathode-ray tube comprises an electron gun containing a heated cathode, focusing means, deflecting means and a fluorescent screen, said cathode having a working surface and comprising a container body, a sintered porous body forming a closing member for said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from within said chamber onto the outer surface of said porous sintered body, a supply substance provided within said supply chamber and adapted to work as the active material for said cathode, said porous body being formed by a metallic material having a content of at least one of the platinum metals and adapted to form an alloy with at least a substantial portion of the metal yielded by said supply substance along their contacting surfaces, said supply substance containing at least one of the alkaline and alkaline earth metals in form of an alloy and adapted to yield, at least in the activated state of the cathode, such a metal in its metallic
  • thevelocity of vaporization of said alloy is determined by theratio of the active and the inactive components contained in said alloy.
  • Such a cathode according to the invention is particularly adapted for use in television receiver tubes, as the electron beam produced by the cathode is practically free from negative ions and causes no ion spot on the screen.
  • cathodes are especially suitable comprising a sintered porous body of tungsten and/or molybdenum and/or tantalum and/or niobium and/or hafnium or made of an alloy of' two or more of these metals and further containing tone or more metals of the platinum group and/or which are coated with at least one metal of the platinum group, whereby the activator is a barium alloy, e. g. an alloy :of barium and of one or more metals of the group III of the periodic system. Good results have been obtained with an activator consisting of.50% barium and 50% aluminum. The speed of vaporization may be determined by the percentage of the components, i. e.
  • the composition of the activator determines also the working temperature. According to our experiments suicient quantities of barium reached at a temperature under 1000 C. in the case of using a barium alloy containing 50% barium and 50% aluminum. Barium forms a temporary alloy with the metals of the platinum group upon the active surface of the porous body. Thereby the tension of the metallic barium is lowered and thus the life-time of the cathode lengthened. In other cases good results have been obtained with activators consisting of 20% barium and 80% aluminum.
  • Fig. 1 shows a cathode ray tube for use in television receivers in accordance with the invention
  • Fig. 2 shows a cathode constructed for the television tube according to Fig. 1 and attached to the inner mantle surface of a Wehneltcylinder.
  • Fig. 3 illustrates partly in section a perspective view of a porous body made in compliance with the present invention. It is to be pointed out thatfor sake of clarity-the gures are not drawn to scale neither as regards their whole nor the interrelation of the parts illustrated.
  • the invention is applicable to any type of television tubes, but for purpose of illustration a conventional television tube is shown in the drawing with an envelope 1 enclosing an electron gun structure in the neck portion 2 of the envelope with the usual electrodes and a fluorescent screen 3 in the bulbulare portion of the envelope.
  • the fluorescent layer consists e. g. of zinc sulphide.
  • the electron gun contains a heated cathode or source of free electrons 4.
  • the electrons leaving the electron gun pass through the hole of the electrode 5 which by being placed at higher or lower negative potentials can control the number of electrons passing.
  • the electrons are accelerated by a positive potential 'on the focusing anode 6.
  • This diaphragm serves to stop all electrons except those making a small angle with the axis of the beam.
  • the beam of electrons thus formed is further accelerated by the potential on the accelerating anode 7 with a hole 8 in its centre and is focused on the screen 3 at the end of the tube by the electron lens set up between the rst and second anodes 6 and 7.
  • the number of electrons, and therefore the brightness of the spot may be controlled by the potential on electrode 5; the focus or sharpness of the spot may be controlled by proper shaping of the electron lens by adjustment of the anode potentials.
  • Two pairs of deflection plates 9 and 10 are provided along the path of the electrons as usual on both sides of a diaphragm 11 provided with a slot 12.
  • the cathode 4 of the tube is shown with more details in Fig. 2 which isV a perspective view and partly an axial section.
  • the cathode comprises a container body 16 made of molybdenum, nickel, tungsten or the like and a sintered porous body 17 hereinafter described in closer details, for serving as a closing means of the container b'ody 16 and forming with the latter a supply chamber 18.
  • a supply substance 19 selected so as to work as the active ma terial of the cathode and the composition of which will hereinafter be more particularly described. With the represented embodiment the supply substance 19 lls up the chamber 18 completely.
  • the container body 16 lits into a cylindrically shapedfvessel 20 made likewisely of molybdenum, nickel, tungsten or the like, leaving a disk like interstice or heating chamber 21 between the bottom of the container body 16 and a disklike insert 22 made of a ceramic material and snugly 4 fitted in the bottom part of the vessel 20.
  • the mutual position of the container body 16, the closing part 17 and the supply substance 19 is determined by a shoulder ⁇ 23 and by a rim 24 of the container body 16, respectively.
  • the mutual position of the container body 16 and the vessel 18 is likewisely secured by a shoulder 25 and a rim 26, respectively, of the vessel 20.
  • the mutual position of the said elements might as well be secured by any suitable means, e. g. by welding.
  • a heating means 27 for the cathode the supply leads of which are designated by reference numerals 28 and 29, respectively, and led through suitably formed registering guiding passages of the ceramic disk 22 and the bottom part of the vessel 20.
  • the heating means 27 is formed as a flat spiral, the turns of which lie in a plane parallel to the bottom surface of the container body 16.
  • the ceramic disk 22 might be substituted by a disk :of another suitable heat insulating material or dispensed with altogether.
  • the cathode as a whole is secured by annular fastening means 30 and 31, respectively, made of nickel, molybdenum or the like, to a disk 32 made of ceramic material, which, in turn, is secured by means of ring-shaped fastening means 33 and 34, respectively, made likewisely of nickel, molybdenum or the like, to the inner mantle surface of a Wehnelt-cylinder 35 well known in the art.
  • the Wehnelt-cylinder 35 is composed of two symmetrical parts each of which is provided with brackets 36 and 37, respectively, forming together with their counterparts 36 and 37 loops 38 and 39 which are slidably arranged on rods 40 and 41 of ceramic material as is known in the art.
  • the supply substance 19 contains according to this invention at least one of the alkaline metals and/or the alkaline earth metals in the form of an alloy the components being selected so as to yield, at least in the activated condition of the cathode, such a metal in its metallic state as has been set forth in the preamble of this specification.
  • the closing member 17 formed by a sintered porous body As to the closing member 17 formed by a sintered porous body, a portion thereof is illustrated on a larger scale in Fig. 3. As the result of the sintering process the grains of the material'forming the closing member 17 adhere to one another so as to confine the pores 42 therebetween which obviously form the only passages from within the supply chamber 18 onto the outer surface of the closing member 17.
  • the porous body is formed at least partly by a metallic material having a content of at least one of the platinum metals.
  • the alkaline metal or the alkaline earth metal yielded in its metallic state by the supply substance 19 through the passages 42 in the porous body forming the closing member forms an alloy with the platinum metals of the closing member along their contacting surfaces thereby continuously rendering active the working surface 43 of the cathode.
  • the porous body canwithin the scope of the invention-'contain various compositions.
  • the barium may be wholly or partly substituted by or mixed with any other alkaline metal or earth alkaline metal.
  • Especially good results have been obtained by an alloy containing about 40% barium, about 10% calcium and about 50% aluminum.
  • aluminum may be mixed with or substituted by another suitable metal.
  • Such metals are those of the group III of the Periodic System, for instance rare earth metals as scandium or yttrium,
  • alloys especially adapted for the porous body according to the invention are:
  • the cathode according to the invention has further advantages, especially the long lifetime of the tube, as a result of the new cathode being a so-called supply cathode.
  • a cathode-ray tube for use in television receivers, having an electron gun, accelerating electrodes, deecting means and a fluorescent screen, the cathode of the electron gun being a supply cathode having a working surface and comprising a container body, a sintered porous body for serving as ⁇ a closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from within said chamber onto the outer surface of said porous body, a supply substance provided within said supply chamber and adapted to work as the active material for said cathodes, said porous body being formed by a metallic material having a content of at least one of the platinum metals and adapted to form an alloy with at least a substantial portion of the metal yielded by said supply substance along their contacting surfaces, said supply substance containing at least one of the alkaline metals and alkaline earth metals in form of an alloy and adapted to yield, at least in the activated condition of the
  • a cathode-ray tube for use in television receivers, having an electron gun, accelerating electrons, detlecting means, and a uorescent screen, the cathode of the electron gun being a supply cathode having a working surface and comprising a container body, a sintered porous body for serving as ⁇ a closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from within said supply chamber onto the outer surface of said porous body, a supply substance provided Within said supply chamber ⁇ and adapted to Work as the active material for said cathode, said porous body being formed by a metallic material having a content of at least one of the groups of the platinum metals and adapted to form an alloy with at least the substantial portion of the metal yielded by said supply substance along their contacting surfaces, said supply substance containing at least one of the alkaline metals and alkaline earth metals in form of an alloy and adapted to yield, at least
  • a cathode-ray tube for use in television receivers, said cathode comprising a container body, a sintered porous body for serving as a closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from within said chamber onto the outer surface of said porous body, a supply substance provided within said supply chamber and adapted to work as the active material for said cathode, said supply substance consisting of an alloy made, on the one hand, of at least one of the metals barium, strontium, calcium and, on the other hand, of at least one metal of the group III of the Periodic System, the velocity of vaporization of said alloy being determined by the ratio of the active and inactive components of said alloy.
  • a cathode for cathode-ray tubes for use in television receivers, said cathode comprising a container body, a sintered porous body for serving as ya closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from within said chamber onto the outer surface of said porous body, a supply substance provided Within said supply chamber and adapted to work as the active material for said cathode, said supply substance consisting of an alloy made, on the one hand, of barium and strontium and, on the other hand, of at least one material of the group III of the Periodic System, the velocity of vaporization of said alloy being determined by the ratio of the active and inactive components of said alloy.
  • a cathode for cathode-ray tubes for use in television receivers, said cathode comprising a container body, a sintered porous body for serving as a closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from Within said chamber onto the outer surface of said porous body, a supply substance provided within said supply chamber and adapted to work as the active material for said cathode, said supply substance consisting of an alloy made, on the one hand, of barium and calcium and, on the other hand, of at least one metal of the group III of the Periodic System, the velocity of vaporization being determined by the ratio of the active and inactive components of said alloy.
  • a cathode for ⁇ cathode-ray tubes for use in television receivers, said cathode comprising a container body, a sintered porous body for serving as a closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from Within said chamber onto the outer surface of said porous body, a supply substance provided within said supply chamber and adapted to Work as the active material for said cathode, said supply substance consisting of a barium-aluminum alloy, the velocity of vaporization being determined by the ratio of the active and inactive components of said alloy.
  • a cathode according to claim 6, comprising a supply substance as activator containing at least 20% barium, the velocity of vaporization being determined by the ratio of the active and inactive components of said alloy.
  • a cathode for cathode-ray tubes for use in television receivers, said cathode comprising a container body, a sintered porous body for serving as a closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from within said chamber onto the outer surface of said porous body, a supply substance provided Within said supply chamber and adapted to Work as the active material for said cathode, said supply substance consisting of an alloy containing about 50% barium and about 50% aluminum, the velocity of vaporization being determined by the ratio of the active and inactive components of said alloy.
  • a cathode for cathode-ray tubes for use in television receivers, said cathode comprising a container body, a sintered porous body for serving as a closing member of lsaid container body, said container body and said porous body enclosing a supply chamber,
  • a supply substance provided within ⁇ said :supply chamber and adapted to work as the active material for said cathode, said supply substance consisting o-f an alloy containing about 40% barium, about 10% calcium and about 50% aluminum, the velocity of vaporization being determined by the ratio of the active and inactive components of said alloy.
  • a cathode for cathode-ray tubes for use in television receivers, said cathode comprising a container body, a sintered porous body for serving as a closing member of said container body, said container body and said porous body enclosing a supply chamber, the pores of said porous body forming the only passages from within said chamber onto the outer surface of said porous body, a supply substance provided within said supply chamber and adapted to Work as the active material for said cathode, said supply substance consisting of an alloy containing about 40% barium, 20% aluminum and 40% nickel, the velocity of vaporization being determined by the ratio of the active and inactive components of said alloy.

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  • Solid Thermionic Cathode (AREA)
  • Powder Metallurgy (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US465489A 1953-11-05 1954-10-29 Cathode-ray tubes for use in television receivers Expired - Lifetime US2798180A (en)

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HU792046X 1953-11-05

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US (1) US2798180A (ko)
DE (1) DE1094375B (ko)
FR (1) FR1112744A (ko)
GB (1) GB792046A (ko)
HU (1) HU143979A (ko)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2902620A (en) * 1953-03-04 1959-09-01 Egyesuelt Izzolampa Supply cathode
US4547694A (en) * 1981-12-31 1985-10-15 U.S. Philips Corporation Low-loss cathode for a television camera tube

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2188771B (en) * 1986-04-01 1990-12-19 Ceradyne Inc Dispenser cathode and method of manufacture therefor
KR920001335B1 (ko) * 1989-11-10 1992-02-10 삼성전관 주식회사 디스펜서 음극

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2031721A (en) * 1930-07-17 1936-02-25 Loewe Siegmund Method of manufacturing highly emissive cathodes
US2131204A (en) * 1936-01-15 1938-09-27 Siemens Ag Indirectly heated thermionic cathode
US2201167A (en) * 1937-03-09 1940-05-21 Germeshausen Kenneth Joseph Gaseous-discharge device
US2647216A (en) * 1950-04-01 1953-07-28 Rca Corp Dispenser cathode

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2031721A (en) * 1930-07-17 1936-02-25 Loewe Siegmund Method of manufacturing highly emissive cathodes
US2131204A (en) * 1936-01-15 1938-09-27 Siemens Ag Indirectly heated thermionic cathode
US2201167A (en) * 1937-03-09 1940-05-21 Germeshausen Kenneth Joseph Gaseous-discharge device
US2647216A (en) * 1950-04-01 1953-07-28 Rca Corp Dispenser cathode

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2902620A (en) * 1953-03-04 1959-09-01 Egyesuelt Izzolampa Supply cathode
US4547694A (en) * 1981-12-31 1985-10-15 U.S. Philips Corporation Low-loss cathode for a television camera tube

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DE1094375B (de) 1960-12-08
FR1112744A (fr) 1956-03-19
HU143979A (ko)
GB792046A (en) 1958-03-19

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